// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * OMAP2 McSPI controller driver
 *
 * Copyright (C) 2005, 2006 Nokia Corporation
 * Author:      Samuel Ortiz <samuel.ortiz@nokia.com> and
 *              Juha Yrjola <juha.yrjola@nokia.com>
 */

#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/dma-mapping.h>
#include <linux/dmaengine.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/gcd.h>

#include <linux/spi/spi.h>

#include <linux/platform_data/spi-omap2-mcspi.h>

#define OMAP2_MCSPI_MAX_FREQ            48000000
#define OMAP2_MCSPI_MAX_DIVIDER         4096
#define OMAP2_MCSPI_MAX_FIFODEPTH       64
#define OMAP2_MCSPI_MAX_FIFOWCNT        0xFFFF
#define SPI_AUTOSUSPEND_TIMEOUT         2000

#define OMAP2_MCSPI_REVISION            0x00
#define OMAP2_MCSPI_SYSSTATUS           0x14
#define OMAP2_MCSPI_IRQSTATUS           0x18
#define OMAP2_MCSPI_IRQENABLE           0x1c
#define OMAP2_MCSPI_WAKEUPENABLE        0x20
#define OMAP2_MCSPI_SYST                0x24
#define OMAP2_MCSPI_MODULCTRL           0x28
#define OMAP2_MCSPI_XFERLEVEL           0x7c

/* per-channel banks, 0x14 bytes each, first is: */
#define OMAP2_MCSPI_CHCONF0             0x2c
#define OMAP2_MCSPI_CHSTAT0             0x30
#define OMAP2_MCSPI_CHCTRL0             0x34
#define OMAP2_MCSPI_TX0                 0x38
#define OMAP2_MCSPI_RX0                 0x3c

/* per-register bitmasks: */
#define OMAP2_MCSPI_IRQSTATUS_EOW       BIT(17)

#define OMAP2_MCSPI_MODULCTRL_SINGLE    BIT(0)
#define OMAP2_MCSPI_MODULCTRL_MS        BIT(2)
#define OMAP2_MCSPI_MODULCTRL_STEST     BIT(3)

#define OMAP2_MCSPI_CHCONF_PHA          BIT(0)
#define OMAP2_MCSPI_CHCONF_POL          BIT(1)
#define OMAP2_MCSPI_CHCONF_CLKD_MASK    (0x0f << 2)
#define OMAP2_MCSPI_CHCONF_EPOL         BIT(6)
#define OMAP2_MCSPI_CHCONF_WL_MASK      (0x1f << 7)
#define OMAP2_MCSPI_CHCONF_TRM_RX_ONLY  BIT(12)
#define OMAP2_MCSPI_CHCONF_TRM_TX_ONLY  BIT(13)
#define OMAP2_MCSPI_CHCONF_TRM_MASK     (0x03 << 12)
#define OMAP2_MCSPI_CHCONF_DMAW         BIT(14)
#define OMAP2_MCSPI_CHCONF_DMAR         BIT(15)
#define OMAP2_MCSPI_CHCONF_DPE0         BIT(16)
#define OMAP2_MCSPI_CHCONF_DPE1         BIT(17)
#define OMAP2_MCSPI_CHCONF_IS           BIT(18)
#define OMAP2_MCSPI_CHCONF_TURBO        BIT(19)
#define OMAP2_MCSPI_CHCONF_FORCE        BIT(20)
#define OMAP2_MCSPI_CHCONF_FFET         BIT(27)
#define OMAP2_MCSPI_CHCONF_FFER         BIT(28)
#define OMAP2_MCSPI_CHCONF_CLKG         BIT(29)

#define OMAP2_MCSPI_CHSTAT_RXS          BIT(0)
#define OMAP2_MCSPI_CHSTAT_TXS          BIT(1)
#define OMAP2_MCSPI_CHSTAT_EOT          BIT(2)
#define OMAP2_MCSPI_CHSTAT_TXFFE        BIT(3)

#define OMAP2_MCSPI_CHCTRL_EN           BIT(0)
#define OMAP2_MCSPI_CHCTRL_EXTCLK_MASK  (0xff << 8)

#define OMAP2_MCSPI_WAKEUPENABLE_WKEN   BIT(0)

/* We have 2 DMA channels per CS, one for RX and one for TX */
struct omap2_mcspi_dma {
        struct dma_chan *dma_tx;
        struct dma_chan *dma_rx;

        struct completion dma_tx_completion;
        struct completion dma_rx_completion;

        char dma_rx_ch_name[14];
        char dma_tx_ch_name[14];
};

/* use PIO for small transfers, avoiding DMA setup/teardown overhead and
 * cache operations; better heuristics consider wordsize and bitrate.
 */
#define DMA_MIN_BYTES                   160


/*
 * Used for context save and restore, structure members to be updated whenever
 * corresponding registers are modified.
 */
struct omap2_mcspi_regs {
        u32 modulctrl;
        u32 wakeupenable;
        struct list_head cs;
};

struct omap2_mcspi {
        struct completion       txdone;
        struct spi_master       *master;
        /* Virtual base address of the controller */
        void __iomem            *base;
        unsigned long           phys;
        /* SPI1 has 4 channels, while SPI2 has 2 */
        struct omap2_mcspi_dma  *dma_channels;
        struct device           *dev;
        struct omap2_mcspi_regs ctx;
        int                     fifo_depth;
        bool                    slave_aborted;
        unsigned int            pin_dir:1;
        size_t                  max_xfer_len;
};

struct omap2_mcspi_cs {
        void __iomem            *base;
        unsigned long           phys;
        int                     word_len;
        u16                     mode;
        struct list_head        node;
        /* Context save and restore shadow register */
        u32                     chconf0, chctrl0;
};

static inline void mcspi_write_reg(struct spi_master *master,
                int idx, u32 val)
{
        struct omap2_mcspi *mcspi = spi_master_get_devdata(master);

        writel_relaxed(val, mcspi->base + idx);
}

static inline u32 mcspi_read_reg(struct spi_master *master, int idx)
{
        struct omap2_mcspi *mcspi = spi_master_get_devdata(master);

        return readl_relaxed(mcspi->base + idx);
}

static inline void mcspi_write_cs_reg(const struct spi_device *spi,
                int idx, u32 val)
{
        struct omap2_mcspi_cs   *cs = spi->controller_state;

        writel_relaxed(val, cs->base +  idx);
}

static inline u32 mcspi_read_cs_reg(const struct spi_device *spi, int idx)
{
        struct omap2_mcspi_cs   *cs = spi->controller_state;

        return readl_relaxed(cs->base + idx);
}

static inline u32 mcspi_cached_chconf0(const struct spi_device *spi)
{
        struct omap2_mcspi_cs *cs = spi->controller_state;

        return cs->chconf0;
}

static inline void mcspi_write_chconf0(const struct spi_device *spi, u32 val)
{
        struct omap2_mcspi_cs *cs = spi->controller_state;

        cs->chconf0 = val;
        mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCONF0, val);
        mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCONF0);
}

static inline int mcspi_bytes_per_word(int word_len)
{
        if (word_len <= 8)
                return 1;
        else if (word_len <= 16)
                return 2;
        else /* word_len <= 32 */
                return 4;
}

static void omap2_mcspi_set_dma_req(const struct spi_device *spi,
                int is_read, int enable)
{
        u32 l, rw;

        l = mcspi_cached_chconf0(spi);

        if (is_read) /* 1 is read, 0 write */
                rw = OMAP2_MCSPI_CHCONF_DMAR;
        else
                rw = OMAP2_MCSPI_CHCONF_DMAW;

        if (enable)
                l |= rw;
        else
                l &= ~rw;

        mcspi_write_chconf0(spi, l);
}

static void omap2_mcspi_set_enable(const struct spi_device *spi, int enable)
{
        struct omap2_mcspi_cs *cs = spi->controller_state;
        u32 l;

        l = cs->chctrl0;
        if (enable)
                l |= OMAP2_MCSPI_CHCTRL_EN;
        else
                l &= ~OMAP2_MCSPI_CHCTRL_EN;
        cs->chctrl0 = l;
        mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCTRL0, cs->chctrl0);
        /* Flash post-writes */
        mcspi_read_cs_reg(spi, OMAP2_MCSPI_CHCTRL0);
}

static void omap2_mcspi_set_cs(struct spi_device *spi, bool enable)
{
        struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
        u32 l;

        /* The controller handles the inverted chip selects
         * using the OMAP2_MCSPI_CHCONF_EPOL bit so revert
         * the inversion from the core spi_set_cs function.
         */
        if (spi->mode & SPI_CS_HIGH)
                enable = !enable;

        if (spi->controller_state) {
                int err = pm_runtime_get_sync(mcspi->dev);
                if (err < 0) {
                        pm_runtime_put_noidle(mcspi->dev);
                        dev_err(mcspi->dev, "failed to get sync: %d\n", err);
                        return;
                }

                l = mcspi_cached_chconf0(spi);

                if (enable)
                        l &= ~OMAP2_MCSPI_CHCONF_FORCE;
                else
                        l |= OMAP2_MCSPI_CHCONF_FORCE;

                mcspi_write_chconf0(spi, l);

                pm_runtime_mark_last_busy(mcspi->dev);
                pm_runtime_put_autosuspend(mcspi->dev);
        }
}

static void omap2_mcspi_set_mode(struct spi_master *master)
{
        struct omap2_mcspi      *mcspi = spi_master_get_devdata(master);
        struct omap2_mcspi_regs *ctx = &mcspi->ctx;
        u32 l;

        /*
         * Choose master or slave mode
         */
        l = mcspi_read_reg(master, OMAP2_MCSPI_MODULCTRL);
        l &= ~(OMAP2_MCSPI_MODULCTRL_STEST);
        if (spi_controller_is_slave(master)) {
                l |= (OMAP2_MCSPI_MODULCTRL_MS);
        } else {
                l &= ~(OMAP2_MCSPI_MODULCTRL_MS);
                l |= OMAP2_MCSPI_MODULCTRL_SINGLE;
        }
        mcspi_write_reg(master, OMAP2_MCSPI_MODULCTRL, l);

        ctx->modulctrl = l;
}

static void omap2_mcspi_set_fifo(const struct spi_device *spi,
                                struct spi_transfer *t, int enable)
{
        struct spi_master *master = spi->master;
        struct omap2_mcspi_cs *cs = spi->controller_state;
        struct omap2_mcspi *mcspi;
        unsigned int wcnt;
        int max_fifo_depth, bytes_per_word;
        u32 chconf, xferlevel;

        mcspi = spi_master_get_devdata(master);

        chconf = mcspi_cached_chconf0(spi);
        if (enable) {
                bytes_per_word = mcspi_bytes_per_word(cs->word_len);
                if (t->len % bytes_per_word != 0)
                        goto disable_fifo;

                if (t->rx_buf != NULL && t->tx_buf != NULL)
                        max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH / 2;
                else
                        max_fifo_depth = OMAP2_MCSPI_MAX_FIFODEPTH;

                wcnt = t->len / bytes_per_word;
                if (wcnt > OMAP2_MCSPI_MAX_FIFOWCNT)
                        goto disable_fifo;

                xferlevel = wcnt << 16;
                if (t->rx_buf != NULL) {
                        chconf |= OMAP2_MCSPI_CHCONF_FFER;
                        xferlevel |= (bytes_per_word - 1) << 8;
                }

                if (t->tx_buf != NULL) {
                        chconf |= OMAP2_MCSPI_CHCONF_FFET;
                        xferlevel |= bytes_per_word - 1;
                }

                mcspi_write_reg(master, OMAP2_MCSPI_XFERLEVEL, xferlevel);
                mcspi_write_chconf0(spi, chconf);
                mcspi->fifo_depth = max_fifo_depth;

                return;
        }

disable_fifo:
        if (t->rx_buf != NULL)
                chconf &= ~OMAP2_MCSPI_CHCONF_FFER;

        if (t->tx_buf != NULL)
                chconf &= ~OMAP2_MCSPI_CHCONF_FFET;

        mcspi_write_chconf0(spi, chconf);
        mcspi->fifo_depth = 0;
}

static int mcspi_wait_for_reg_bit(void __iomem *reg, unsigned long bit)
{
        unsigned long timeout;

        timeout = jiffies + msecs_to_jiffies(1000);
        while (!(readl_relaxed(reg) & bit)) {
                if (time_after(jiffies, timeout)) {
                        if (!(readl_relaxed(reg) & bit))
                                return -ETIMEDOUT;
                        else
                                return 0;
                }
                cpu_relax();
        }
        return 0;
}

static int mcspi_wait_for_completion(struct  omap2_mcspi *mcspi,
                                     struct completion *x)
{
        if (spi_controller_is_slave(mcspi->master)) {
                if (wait_for_completion_interruptible(x) ||
                    mcspi->slave_aborted)
                        return -EINTR;
        } else {
                wait_for_completion(x);
        }

        return 0;
}

static void omap2_mcspi_rx_callback(void *data)
{
        struct spi_device *spi = data;
        struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
        struct omap2_mcspi_dma *mcspi_dma = &mcspi->dma_channels[spi->chip_select];

        /* We must disable the DMA RX request */
        omap2_mcspi_set_dma_req(spi, 1, 0);

        complete(&mcspi_dma->dma_rx_completion);
}

static void omap2_mcspi_tx_callback(void *data)
{
        struct spi_device *spi = data;
        struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
        struct omap2_mcspi_dma *mcspi_dma = &mcspi->dma_channels[spi->chip_select];

        /* We must disable the DMA TX request */
        omap2_mcspi_set_dma_req(spi, 0, 0);

        complete(&mcspi_dma->dma_tx_completion);
}

static void omap2_mcspi_tx_dma(struct spi_device *spi,
                                struct spi_transfer *xfer,
                                struct dma_slave_config cfg)
{
        struct omap2_mcspi      *mcspi;
        struct omap2_mcspi_dma  *mcspi_dma;
        struct dma_async_tx_descriptor *tx;

        mcspi = spi_master_get_devdata(spi->master);
        mcspi_dma = &mcspi->dma_channels[spi->chip_select];

        dmaengine_slave_config(mcspi_dma->dma_tx, &cfg);

        tx = dmaengine_prep_slave_sg(mcspi_dma->dma_tx, xfer->tx_sg.sgl,
                                     xfer->tx_sg.nents,
                                     DMA_MEM_TO_DEV,
                                     DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (tx) {
                tx->callback = omap2_mcspi_tx_callback;
                tx->callback_param = spi;
                dmaengine_submit(tx);
        } else {
                /* FIXME: fall back to PIO? */
        }
        dma_async_issue_pending(mcspi_dma->dma_tx);
        omap2_mcspi_set_dma_req(spi, 0, 1);
}

static unsigned
omap2_mcspi_rx_dma(struct spi_device *spi, struct spi_transfer *xfer,
                                struct dma_slave_config cfg,
                                unsigned es)
{
        struct omap2_mcspi      *mcspi;
        struct omap2_mcspi_dma  *mcspi_dma;
        unsigned int            count, transfer_reduction = 0;
        struct scatterlist      *sg_out[2];
        int                     nb_sizes = 0, out_mapped_nents[2], ret, x;
        size_t                  sizes[2];
        u32                     l;
        int                     elements = 0;
        int                     word_len, element_count;
        struct omap2_mcspi_cs   *cs = spi->controller_state;
        void __iomem            *chstat_reg = cs->base + OMAP2_MCSPI_CHSTAT0;
        struct dma_async_tx_descriptor *tx;

        mcspi = spi_master_get_devdata(spi->master);
        mcspi_dma = &mcspi->dma_channels[spi->chip_select];
        count = xfer->len;

        /*
         *  In the "End-of-Transfer Procedure" section for DMA RX in OMAP35x TRM
         *  it mentions reducing DMA transfer length by one element in master
         *  normal mode.
         */
        if (mcspi->fifo_depth == 0)
                transfer_reduction = es;

        word_len = cs->word_len;
        l = mcspi_cached_chconf0(spi);

        if (word_len <= 8)
                element_count = count;
        else if (word_len <= 16)
                element_count = count >> 1;
        else /* word_len <= 32 */
                element_count = count >> 2;


        dmaengine_slave_config(mcspi_dma->dma_rx, &cfg);

        /*
         *  Reduce DMA transfer length by one more if McSPI is
         *  configured in turbo mode.
         */
        if ((l & OMAP2_MCSPI_CHCONF_TURBO) && mcspi->fifo_depth == 0)
                transfer_reduction += es;

        if (transfer_reduction) {
                /* Split sgl into two. The second sgl won't be used. */
                sizes[0] = count - transfer_reduction;
                sizes[1] = transfer_reduction;
                nb_sizes = 2;
        } else {
                /*
                 * Don't bother splitting the sgl. This essentially
                 * clones the original sgl.
                 */
                sizes[0] = count;
                nb_sizes = 1;
        }

        ret = sg_split(xfer->rx_sg.sgl, xfer->rx_sg.nents, 0, nb_sizes,
                       sizes, sg_out, out_mapped_nents, GFP_KERNEL);

        if (ret < 0) {
                dev_err(&spi->dev, "sg_split failed\n");
                return 0;
        }

        tx = dmaengine_prep_slave_sg(mcspi_dma->dma_rx, sg_out[0],
                                     out_mapped_nents[0], DMA_DEV_TO_MEM,
                                     DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
        if (tx) {
                tx->callback = omap2_mcspi_rx_callback;
                tx->callback_param = spi;
                dmaengine_submit(tx);
        } else {
                /* FIXME: fall back to PIO? */
        }

        dma_async_issue_pending(mcspi_dma->dma_rx);
        omap2_mcspi_set_dma_req(spi, 1, 1);

        ret = mcspi_wait_for_completion(mcspi, &mcspi_dma->dma_rx_completion);
        if (ret || mcspi->slave_aborted) {
                dmaengine_terminate_sync(mcspi_dma->dma_rx);
                omap2_mcspi_set_dma_req(spi, 1, 0);
                return 0;
        }

        for (x = 0; x < nb_sizes; x++)
                kfree(sg_out[x]);

        if (mcspi->fifo_depth > 0)
                return count;

        /*
         *  Due to the DMA transfer length reduction the missing bytes must
         *  be read manually to receive all of the expected data.
         */
        omap2_mcspi_set_enable(spi, 0);

        elements = element_count - 1;

        if (l & OMAP2_MCSPI_CHCONF_TURBO) {
                elements--;

                if (!mcspi_wait_for_reg_bit(chstat_reg,
                                            OMAP2_MCSPI_CHSTAT_RXS)) {
                        u32 w;

                        w = mcspi_read_cs_reg(spi, OMAP2_MCSPI_RX0);
                        if (word_len <= 8)
                                ((u8 *)xfer->rx_buf)[elements++] = w;
                        else if (word_len <= 16)
                                ((u16 *)xfer->rx_buf)[elements++] = w;
                        else /* word_len <= 32 */
                                ((u32 *)xfer->rx_buf)[elements++] = w;
                } else {
                        int bytes_per_word = mcspi_bytes_per_word(word_len);
                        dev_err(&spi->dev, "DMA RX penultimate word empty\n");
                        count -= (bytes_per_word << 1);
                        omap2_mcspi_set_enable(spi, 1);
                        return count;
                }
        }
        if (!mcspi_wait_for_reg_bit(chstat_reg, OMAP2_MCSPI_CHSTAT_RXS)) {
                u32 w;

                w = mcspi_read_cs_reg(spi, OMAP2_MCSPI_RX0);
                if (word_len <= 8)
                        ((u8 *)xfer->rx_buf)[elements] = w;
                else if (word_len <= 16)
                        ((u16 *)xfer->rx_buf)[elements] = w;
                else /* word_len <= 32 */
                        ((u32 *)xfer->rx_buf)[elements] = w;
        } else {
                dev_err(&spi->dev, "DMA RX last word empty\n");
                count -= mcspi_bytes_per_word(word_len);
        }
        omap2_mcspi_set_enable(spi, 1);
        return count;
}

static unsigned
omap2_mcspi_txrx_dma(struct spi_device *spi, struct spi_transfer *xfer)
{
        struct omap2_mcspi      *mcspi;
        struct omap2_mcspi_cs   *cs = spi->controller_state;
        struct omap2_mcspi_dma  *mcspi_dma;
        unsigned int            count;
        u8                      *rx;
        const u8                *tx;
        struct dma_slave_config cfg;
        enum dma_slave_buswidth width;
        unsigned es;
        void __iomem            *chstat_reg;
        void __iomem            *irqstat_reg;
        int                     wait_res;

        mcspi = spi_master_get_devdata(spi->master);
        mcspi_dma = &mcspi->dma_channels[spi->chip_select];

        if (cs->word_len <= 8) {
                width = DMA_SLAVE_BUSWIDTH_1_BYTE;
                es = 1;
        } else if (cs->word_len <= 16) {
                width = DMA_SLAVE_BUSWIDTH_2_BYTES;
                es = 2;
        } else {
                width = DMA_SLAVE_BUSWIDTH_4_BYTES;
                es = 4;
        }

        count = xfer->len;

        memset(&cfg, 0, sizeof(cfg));
        cfg.src_addr = cs->phys + OMAP2_MCSPI_RX0;
        cfg.dst_addr = cs->phys + OMAP2_MCSPI_TX0;
        cfg.src_addr_width = width;
        cfg.dst_addr_width = width;
        cfg.src_maxburst = 1;
        cfg.dst_maxburst = 1;

        rx = xfer->rx_buf;
        tx = xfer->tx_buf;

        mcspi->slave_aborted = false;
        reinit_completion(&mcspi_dma->dma_tx_completion);
        reinit_completion(&mcspi_dma->dma_rx_completion);
        reinit_completion(&mcspi->txdone);
        if (tx) {
                /* Enable EOW IRQ to know end of tx in slave mode */
                if (spi_controller_is_slave(spi->master))
                        mcspi_write_reg(spi->master,
                                        OMAP2_MCSPI_IRQENABLE,
                                        OMAP2_MCSPI_IRQSTATUS_EOW);
                omap2_mcspi_tx_dma(spi, xfer, cfg);
        }

        if (rx != NULL)
                count = omap2_mcspi_rx_dma(spi, xfer, cfg, es);

        if (tx != NULL) {
                int ret;

                ret = mcspi_wait_for_completion(mcspi, &mcspi_dma->dma_tx_completion);
                if (ret || mcspi->slave_aborted) {
                        dmaengine_terminate_sync(mcspi_dma->dma_tx);
                        omap2_mcspi_set_dma_req(spi, 0, 0);
                        return 0;
                }

                if (spi_controller_is_slave(mcspi->master)) {
                        ret = mcspi_wait_for_completion(mcspi, &mcspi->txdone);
                        if (ret || mcspi->slave_aborted)
                                return 0;
                }

                if (mcspi->fifo_depth > 0) {
                        irqstat_reg = mcspi->base + OMAP2_MCSPI_IRQSTATUS;

                        if (mcspi_wait_for_reg_bit(irqstat_reg,
                                                OMAP2_MCSPI_IRQSTATUS_EOW) < 0)
                                dev_err(&spi->dev, "EOW timed out\n");

                        mcspi_write_reg(mcspi->master, OMAP2_MCSPI_IRQSTATUS,
                                        OMAP2_MCSPI_IRQSTATUS_EOW);
                }

                /* for TX_ONLY mode, be sure all words have shifted out */
                if (rx == NULL) {
                        chstat_reg = cs->base + OMAP2_MCSPI_CHSTAT0;
                        if (mcspi->fifo_depth > 0) {
                                wait_res = mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_TXFFE);
                                if (wait_res < 0)
                                        dev_err(&spi->dev, "TXFFE timed out\n");
                        } else {
                                wait_res = mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_TXS);
                                if (wait_res < 0)
                                        dev_err(&spi->dev, "TXS timed out\n");
                        }
                        if (wait_res >= 0 &&
                                (mcspi_wait_for_reg_bit(chstat_reg,
                                        OMAP2_MCSPI_CHSTAT_EOT) < 0))
                                dev_err(&spi->dev, "EOT timed out\n");
                }
        }
        return count;
}

static unsigned
omap2_mcspi_txrx_pio(struct spi_device *spi, struct spi_transfer *xfer)
{
        struct omap2_mcspi_cs   *cs = spi->controller_state;
        unsigned int            count, c;
        u32                     l;
        void __iomem            *base = cs->base;
        void __iomem            *tx_reg;
        void __iomem            *rx_reg;
        void __iomem            *chstat_reg;
        int                     word_len;

        count = xfer->len;
        c = count;
        word_len = cs->word_len;

        l = mcspi_cached_chconf0(spi);

        /* We store the pre-calculated register addresses on stack to speed
         * up the transfer loop. */
        tx_reg          = base + OMAP2_MCSPI_TX0;
        rx_reg          = base + OMAP2_MCSPI_RX0;
        chstat_reg      = base + OMAP2_MCSPI_CHSTAT0;

        if (c < (word_len>>3))
                return 0;

        if (word_len <= 8) {
                u8              *rx;
                const u8        *tx;

                rx = xfer->rx_buf;
                tx = xfer->tx_buf;

                do {
                        c -= 1;
                        if (tx != NULL) {
                                if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_TXS) < 0) {
                                        dev_err(&spi->dev, "TXS timed out\n");
                                        goto out;
                                }
                                dev_vdbg(&spi->dev, "write-%d %02x\n",
                                                word_len, *tx);
                                writel_relaxed(*tx++, tx_reg);
                        }
                        if (rx != NULL) {
                                if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_RXS) < 0) {
                                        dev_err(&spi->dev, "RXS timed out\n");
                                        goto out;
                                }

                                if (c == 1 && tx == NULL &&
                                    (l & OMAP2_MCSPI_CHCONF_TURBO)) {
                                        omap2_mcspi_set_enable(spi, 0);
                                        *rx++ = readl_relaxed(rx_reg);
                                        dev_vdbg(&spi->dev, "read-%d %02x\n",
                                                    word_len, *(rx - 1));
                                        if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_RXS) < 0) {
                                                dev_err(&spi->dev,
                                                        "RXS timed out\n");
                                                goto out;
                                        }
                                        c = 0;
                                } else if (c == 0 && tx == NULL) {
                                        omap2_mcspi_set_enable(spi, 0);
                                }

                                *rx++ = readl_relaxed(rx_reg);
                                dev_vdbg(&spi->dev, "read-%d %02x\n",
                                                word_len, *(rx - 1));
                        }
                } while (c);
        } else if (word_len <= 16) {
                u16             *rx;
                const u16       *tx;

                rx = xfer->rx_buf;
                tx = xfer->tx_buf;
                do {
                        c -= 2;
                        if (tx != NULL) {
                                if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_TXS) < 0) {
                                        dev_err(&spi->dev, "TXS timed out\n");
                                        goto out;
                                }
                                dev_vdbg(&spi->dev, "write-%d %04x\n",
                                                word_len, *tx);
                                writel_relaxed(*tx++, tx_reg);
                        }
                        if (rx != NULL) {
                                if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_RXS) < 0) {
                                        dev_err(&spi->dev, "RXS timed out\n");
                                        goto out;
                                }

                                if (c == 2 && tx == NULL &&
                                    (l & OMAP2_MCSPI_CHCONF_TURBO)) {
                                        omap2_mcspi_set_enable(spi, 0);
                                        *rx++ = readl_relaxed(rx_reg);
                                        dev_vdbg(&spi->dev, "read-%d %04x\n",
                                                    word_len, *(rx - 1));
                                        if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_RXS) < 0) {
                                                dev_err(&spi->dev,
                                                        "RXS timed out\n");
                                                goto out;
                                        }
                                        c = 0;
                                } else if (c == 0 && tx == NULL) {
                                        omap2_mcspi_set_enable(spi, 0);
                                }

                                *rx++ = readl_relaxed(rx_reg);
                                dev_vdbg(&spi->dev, "read-%d %04x\n",
                                                word_len, *(rx - 1));
                        }
                } while (c >= 2);
        } else if (word_len <= 32) {
                u32             *rx;
                const u32       *tx;

                rx = xfer->rx_buf;
                tx = xfer->tx_buf;
                do {
                        c -= 4;
                        if (tx != NULL) {
                                if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_TXS) < 0) {
                                        dev_err(&spi->dev, "TXS timed out\n");
                                        goto out;
                                }
                                dev_vdbg(&spi->dev, "write-%d %08x\n",
                                                word_len, *tx);
                                writel_relaxed(*tx++, tx_reg);
                        }
                        if (rx != NULL) {
                                if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_RXS) < 0) {
                                        dev_err(&spi->dev, "RXS timed out\n");
                                        goto out;
                                }

                                if (c == 4 && tx == NULL &&
                                    (l & OMAP2_MCSPI_CHCONF_TURBO)) {
                                        omap2_mcspi_set_enable(spi, 0);
                                        *rx++ = readl_relaxed(rx_reg);
                                        dev_vdbg(&spi->dev, "read-%d %08x\n",
                                                    word_len, *(rx - 1));
                                        if (mcspi_wait_for_reg_bit(chstat_reg,
                                                OMAP2_MCSPI_CHSTAT_RXS) < 0) {
                                                dev_err(&spi->dev,
                                                        "RXS timed out\n");
                                                goto out;
                                        }
                                        c = 0;
                                } else if (c == 0 && tx == NULL) {
                                        omap2_mcspi_set_enable(spi, 0);
                                }

                                *rx++ = readl_relaxed(rx_reg);
                                dev_vdbg(&spi->dev, "read-%d %08x\n",
                                                word_len, *(rx - 1));
                        }
                } while (c >= 4);
        }

        /* for TX_ONLY mode, be sure all words have shifted out */
        if (xfer->rx_buf == NULL) {
                if (mcspi_wait_for_reg_bit(chstat_reg,
                                OMAP2_MCSPI_CHSTAT_TXS) < 0) {
                        dev_err(&spi->dev, "TXS timed out\n");
                } else if (mcspi_wait_for_reg_bit(chstat_reg,
                                OMAP2_MCSPI_CHSTAT_EOT) < 0)
                        dev_err(&spi->dev, "EOT timed out\n");

                /* disable chan to purge rx datas received in TX_ONLY transfer,
                 * otherwise these rx datas will affect the direct following
                 * RX_ONLY transfer.
                 */
                omap2_mcspi_set_enable(spi, 0);
        }
out:
        omap2_mcspi_set_enable(spi, 1);
        return count - c;
}

static u32 omap2_mcspi_calc_divisor(u32 speed_hz)
{
        u32 div;

        for (div = 0; div < 15; div++)
                if (speed_hz >= (OMAP2_MCSPI_MAX_FREQ >> div))
                        return div;

        return 15;
}

/* called only when no transfer is active to this device */
static int omap2_mcspi_setup_transfer(struct spi_device *spi,
                struct spi_transfer *t)
{
        struct omap2_mcspi_cs *cs = spi->controller_state;
        struct omap2_mcspi *mcspi;
        u32 l = 0, clkd = 0, div, extclk = 0, clkg = 0;
        u8 word_len = spi->bits_per_word;
        u32 speed_hz = spi->max_speed_hz;

        mcspi = spi_master_get_devdata(spi->master);

        if (t != NULL && t->bits_per_word)
                word_len = t->bits_per_word;

        cs->word_len = word_len;

        if (t && t->speed_hz)
                speed_hz = t->speed_hz;

        speed_hz = min_t(u32, speed_hz, OMAP2_MCSPI_MAX_FREQ);
        if (speed_hz < (OMAP2_MCSPI_MAX_FREQ / OMAP2_MCSPI_MAX_DIVIDER)) {
                clkd = omap2_mcspi_calc_divisor(speed_hz);
                speed_hz = OMAP2_MCSPI_MAX_FREQ >> clkd;
                clkg = 0;
        } else {
                div = (OMAP2_MCSPI_MAX_FREQ + speed_hz - 1) / speed_hz;
                speed_hz = OMAP2_MCSPI_MAX_FREQ / div;
                clkd = (div - 1) & 0xf;
                extclk = (div - 1) >> 4;
                clkg = OMAP2_MCSPI_CHCONF_CLKG;
        }

        l = mcspi_cached_chconf0(spi);

        /* standard 4-wire master mode:  SCK, MOSI/out, MISO/in, nCS
         * REVISIT: this controller could support SPI_3WIRE mode.
         */
        if (mcspi->pin_dir == MCSPI_PINDIR_D0_IN_D1_OUT) {
                l &= ~OMAP2_MCSPI_CHCONF_IS;
                l &= ~OMAP2_MCSPI_CHCONF_DPE1;
                l |= OMAP2_MCSPI_CHCONF_DPE0;
        } else {
                l |= OMAP2_MCSPI_CHCONF_IS;
                l |= OMAP2_MCSPI_CHCONF_DPE1;
                l &= ~OMAP2_MCSPI_CHCONF_DPE0;
        }

        /* wordlength */
        l &= ~OMAP2_MCSPI_CHCONF_WL_MASK;
        l |= (word_len - 1) << 7;

        /* set chipselect polarity; manage with FORCE */
        if (!(spi->mode & SPI_CS_HIGH))
                l |= OMAP2_MCSPI_CHCONF_EPOL;   /* active-low; normal */
        else
                l &= ~OMAP2_MCSPI_CHCONF_EPOL;

        /* set clock divisor */
        l &= ~OMAP2_MCSPI_CHCONF_CLKD_MASK;
        l |= clkd << 2;

        /* set clock granularity */
        l &= ~OMAP2_MCSPI_CHCONF_CLKG;
        l |= clkg;
        if (clkg) {
                cs->chctrl0 &= ~OMAP2_MCSPI_CHCTRL_EXTCLK_MASK;
                cs->chctrl0 |= extclk << 8;
                mcspi_write_cs_reg(spi, OMAP2_MCSPI_CHCTRL0, cs->chctrl0);
        }

        /* set SPI mode 0..3 */
        if (spi->mode & SPI_CPOL)
                l |= OMAP2_MCSPI_CHCONF_POL;
        else
                l &= ~OMAP2_MCSPI_CHCONF_POL;
        if (spi->mode & SPI_CPHA)
                l |= OMAP2_MCSPI_CHCONF_PHA;
        else
                l &= ~OMAP2_MCSPI_CHCONF_PHA;

        mcspi_write_chconf0(spi, l);

        cs->mode = spi->mode;

        dev_dbg(&spi->dev, "setup: speed %d, sample %s edge, clk %s\n",
                        speed_hz,
                        (spi->mode & SPI_CPHA) ? "trailing" : "leading",
                        (spi->mode & SPI_CPOL) ? "inverted" : "normal");

        return 0;
}

/*
 * Note that we currently allow DMA only if we get a channel
 * for both rx and tx. Otherwise we'll do PIO for both rx and tx.
 */
static int omap2_mcspi_request_dma(struct omap2_mcspi *mcspi,
                                   struct omap2_mcspi_dma *mcspi_dma)
{
        int ret = 0;

        mcspi_dma->dma_rx = dma_request_chan(mcspi->dev,
                                             mcspi_dma->dma_rx_ch_name);
        if (IS_ERR(mcspi_dma->dma_rx)) {
                ret = PTR_ERR(mcspi_dma->dma_rx);
                mcspi_dma->dma_rx = NULL;
                goto no_dma;
        }

        mcspi_dma->dma_tx = dma_request_chan(mcspi->dev,
                                             mcspi_dma->dma_tx_ch_name);

        if (IS_ERR(mcspi_dma->dma_tx)) {
                ret = PTR_ERR(mcspi_dma->dma_tx);
                mcspi_dma->dma_tx = NULL;
                dma_release_channel(mcspi_dma->dma_rx);
                mcspi_dma->dma_rx = NULL;
        }

        init_completion(&mcspi_dma->dma_rx_completion);
        init_completion(&mcspi_dma->dma_tx_completion);

no_dma:
        return ret;
}

static void omap2_mcspi_release_dma(struct spi_master *master)
{
        struct omap2_mcspi *mcspi = spi_master_get_devdata(master);
        struct omap2_mcspi_dma  *mcspi_dma;
        int i;

        for (i = 0; i < master->num_chipselect; i++) {
                mcspi_dma = &mcspi->dma_channels[i];

                if (mcspi_dma->dma_rx) {
                        dma_release_channel(mcspi_dma->dma_rx);
                        mcspi_dma->dma_rx = NULL;
                }
                if (mcspi_dma->dma_tx) {
                        dma_release_channel(mcspi_dma->dma_tx);
                        mcspi_dma->dma_tx = NULL;
                }
        }
}

static void omap2_mcspi_cleanup(struct spi_device *spi)
{
        struct omap2_mcspi_cs   *cs;

        if (spi->controller_state) {
                /* Unlink controller state from context save list */
                cs = spi->controller_state;
                list_del(&cs->node);

                kfree(cs);
        }
}

static int omap2_mcspi_setup(struct spi_device *spi)
{
        bool                    initial_setup = false;
        int                     ret;
        struct omap2_mcspi      *mcspi = spi_master_get_devdata(spi->master);
        struct omap2_mcspi_regs *ctx = &mcspi->ctx;
        struct omap2_mcspi_cs   *cs = spi->controller_state;

        if (!cs) {
                cs = kzalloc(sizeof(*cs), GFP_KERNEL);
                if (!cs)
                        return -ENOMEM;
                cs->base = mcspi->base + spi->chip_select * 0x14;
                cs->phys = mcspi->phys + spi->chip_select * 0x14;
                cs->mode = 0;
                cs->chconf0 = 0;
                cs->chctrl0 = 0;
                spi->controller_state = cs;
                /* Link this to context save list */
                list_add_tail(&cs->node, &ctx->cs);
                initial_setup = true;
        }

        ret = pm_runtime_get_sync(mcspi->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(mcspi->dev);
                if (initial_setup)
                        omap2_mcspi_cleanup(spi);

                return ret;
        }

        ret = omap2_mcspi_setup_transfer(spi, NULL);
        if (ret && initial_setup)
                omap2_mcspi_cleanup(spi);

        pm_runtime_mark_last_busy(mcspi->dev);
        pm_runtime_put_autosuspend(mcspi->dev);

        return ret;
}

static irqreturn_t omap2_mcspi_irq_handler(int irq, void *data)
{
        struct omap2_mcspi *mcspi = data;
        u32 irqstat;

        irqstat = mcspi_read_reg(mcspi->master, OMAP2_MCSPI_IRQSTATUS);
        if (!irqstat)
                return IRQ_NONE;

        /* Disable IRQ and wakeup slave xfer task */
        mcspi_write_reg(mcspi->master, OMAP2_MCSPI_IRQENABLE, 0);
        if (irqstat & OMAP2_MCSPI_IRQSTATUS_EOW)
                complete(&mcspi->txdone);

        return IRQ_HANDLED;
}

static int omap2_mcspi_slave_abort(struct spi_master *master)
{
        struct omap2_mcspi *mcspi = spi_master_get_devdata(master);
        struct omap2_mcspi_dma *mcspi_dma = mcspi->dma_channels;

        mcspi->slave_aborted = true;
        complete(&mcspi_dma->dma_rx_completion);
        complete(&mcspi_dma->dma_tx_completion);
        complete(&mcspi->txdone);

        return 0;
}

static int omap2_mcspi_transfer_one(struct spi_master *master,
                                    struct spi_device *spi,
                                    struct spi_transfer *t)
{

        /* We only enable one channel at a time -- the one whose message is
         * -- although this controller would gladly
         * arbitrate among multiple channels.  This corresponds to "single
         * channel" master mode.  As a side effect, we need to manage the
         * chipselect with the FORCE bit ... CS != channel enable.
         */

        struct omap2_mcspi              *mcspi;
        struct omap2_mcspi_dma          *mcspi_dma;
        struct omap2_mcspi_cs           *cs;
        struct omap2_mcspi_device_config *cd;
        int                             par_override = 0;
        int                             status = 0;
        u32                             chconf;

        mcspi = spi_master_get_devdata(master);
        mcspi_dma = mcspi->dma_channels + spi->chip_select;
        cs = spi->controller_state;
        cd = spi->controller_data;

        /*
         * The slave driver could have changed spi->mode in which case
         * it will be different from cs->mode (the current hardware setup).
         * If so, set par_override (even though its not a parity issue) so
         * omap2_mcspi_setup_transfer will be called to configure the hardware
         * with the correct mode on the first iteration of the loop below.
         */
        if (spi->mode != cs->mode)
                par_override = 1;

        omap2_mcspi_set_enable(spi, 0);

        if (spi->cs_gpiod)
                omap2_mcspi_set_cs(spi, spi->mode & SPI_CS_HIGH);

        if (par_override ||
            (t->speed_hz != spi->max_speed_hz) ||
            (t->bits_per_word != spi->bits_per_word)) {
                par_override = 1;
                status = omap2_mcspi_setup_transfer(spi, t);
                if (status < 0)
                        goto out;
                if (t->speed_hz == spi->max_speed_hz &&
                    t->bits_per_word == spi->bits_per_word)
                        par_override = 0;
        }
        if (cd && cd->cs_per_word) {
                chconf = mcspi->ctx.modulctrl;
                chconf &= ~OMAP2_MCSPI_MODULCTRL_SINGLE;
                mcspi_write_reg(master, OMAP2_MCSPI_MODULCTRL, chconf);
                mcspi->ctx.modulctrl =
                        mcspi_read_cs_reg(spi, OMAP2_MCSPI_MODULCTRL);
        }

        chconf = mcspi_cached_chconf0(spi);
        chconf &= ~OMAP2_MCSPI_CHCONF_TRM_MASK;
        chconf &= ~OMAP2_MCSPI_CHCONF_TURBO;

        if (t->tx_buf == NULL)
                chconf |= OMAP2_MCSPI_CHCONF_TRM_RX_ONLY;
        else if (t->rx_buf == NULL)
                chconf |= OMAP2_MCSPI_CHCONF_TRM_TX_ONLY;

        if (cd && cd->turbo_mode && t->tx_buf == NULL) {
                /* Turbo mode is for more than one word */
                if (t->len > ((cs->word_len + 7) >> 3))
                        chconf |= OMAP2_MCSPI_CHCONF_TURBO;
        }

        mcspi_write_chconf0(spi, chconf);

        if (t->len) {
                unsigned        count;

                if ((mcspi_dma->dma_rx && mcspi_dma->dma_tx) &&
                    master->cur_msg_mapped &&
                    master->can_dma(master, spi, t))
                        omap2_mcspi_set_fifo(spi, t, 1);

                omap2_mcspi_set_enable(spi, 1);

                /* RX_ONLY mode needs dummy data in TX reg */
                if (t->tx_buf == NULL)
                        writel_relaxed(0, cs->base
                                        + OMAP2_MCSPI_TX0);

                if ((mcspi_dma->dma_rx && mcspi_dma->dma_tx) &&
                    master->cur_msg_mapped &&
                    master->can_dma(master, spi, t))
                        count = omap2_mcspi_txrx_dma(spi, t);
                else
                        count = omap2_mcspi_txrx_pio(spi, t);

                if (count != t->len) {
                        status = -EIO;
                        goto out;
                }
        }

        omap2_mcspi_set_enable(spi, 0);

        if (mcspi->fifo_depth > 0)
                omap2_mcspi_set_fifo(spi, t, 0);

out:
        /* Restore defaults if they were overriden */
        if (par_override) {
                par_override = 0;
                status = omap2_mcspi_setup_transfer(spi, NULL);
        }

        if (cd && cd->cs_per_word) {
                chconf = mcspi->ctx.modulctrl;
                chconf |= OMAP2_MCSPI_MODULCTRL_SINGLE;
                mcspi_write_reg(master, OMAP2_MCSPI_MODULCTRL, chconf);
                mcspi->ctx.modulctrl =
                        mcspi_read_cs_reg(spi, OMAP2_MCSPI_MODULCTRL);
        }

        omap2_mcspi_set_enable(spi, 0);

        if (spi->cs_gpiod)
                omap2_mcspi_set_cs(spi, !(spi->mode & SPI_CS_HIGH));

        if (mcspi->fifo_depth > 0 && t)
                omap2_mcspi_set_fifo(spi, t, 0);

        return status;
}

static int omap2_mcspi_prepare_message(struct spi_master *master,
                                       struct spi_message *msg)
{
        struct omap2_mcspi      *mcspi = spi_master_get_devdata(master);
        struct omap2_mcspi_regs *ctx = &mcspi->ctx;
        struct omap2_mcspi_cs   *cs;

        /* Only a single channel can have the FORCE bit enabled
         * in its chconf0 register.
         * Scan all channels and disable them except the current one.
         * A FORCE can remain from a last transfer having cs_change enabled
         */
        list_for_each_entry(cs, &ctx->cs, node) {
                if (msg->spi->controller_state == cs)
                        continue;

                if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE)) {
                        cs->chconf0 &= ~OMAP2_MCSPI_CHCONF_FORCE;
                        writel_relaxed(cs->chconf0,
                                        cs->base + OMAP2_MCSPI_CHCONF0);
                        readl_relaxed(cs->base + OMAP2_MCSPI_CHCONF0);
                }
        }

        return 0;
}

static bool omap2_mcspi_can_dma(struct spi_master *master,
                                struct spi_device *spi,
                                struct spi_transfer *xfer)
{
        struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
        struct omap2_mcspi_dma *mcspi_dma =
                &mcspi->dma_channels[spi->chip_select];

        if (!mcspi_dma->dma_rx || !mcspi_dma->dma_tx)
                return false;

        if (spi_controller_is_slave(master))
                return true;

        master->dma_rx = mcspi_dma->dma_rx;
        master->dma_tx = mcspi_dma->dma_tx;

        return (xfer->len >= DMA_MIN_BYTES);
}

static size_t omap2_mcspi_max_xfer_size(struct spi_device *spi)
{
        struct omap2_mcspi *mcspi = spi_master_get_devdata(spi->master);
        struct omap2_mcspi_dma *mcspi_dma =
                &mcspi->dma_channels[spi->chip_select];

        if (mcspi->max_xfer_len && mcspi_dma->dma_rx)
                return mcspi->max_xfer_len;

        return SIZE_MAX;
}

static int omap2_mcspi_controller_setup(struct omap2_mcspi *mcspi)
{
        struct spi_master       *master = mcspi->master;
        struct omap2_mcspi_regs *ctx = &mcspi->ctx;
        int                     ret = 0;

        ret = pm_runtime_get_sync(mcspi->dev);
        if (ret < 0) {
                pm_runtime_put_noidle(mcspi->dev);

                return ret;
        }

        mcspi_write_reg(master, OMAP2_MCSPI_WAKEUPENABLE,
                        OMAP2_MCSPI_WAKEUPENABLE_WKEN);
        ctx->wakeupenable = OMAP2_MCSPI_WAKEUPENABLE_WKEN;

        omap2_mcspi_set_mode(master);
        pm_runtime_mark_last_busy(mcspi->dev);
        pm_runtime_put_autosuspend(mcspi->dev);
        return 0;
}

static int omap_mcspi_runtime_suspend(struct device *dev)
{
        int error;

        error = pinctrl_pm_select_idle_state(dev);
        if (error)
                dev_warn(dev, "%s: failed to set pins: %i\n", __func__, error);

        return 0;
}

/*
 * When SPI wake up from off-mode, CS is in activate state. If it was in
 * inactive state when driver was suspend, then force it to inactive state at
 * wake up.
 */
static int omap_mcspi_runtime_resume(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct omap2_mcspi *mcspi = spi_master_get_devdata(master);
        struct omap2_mcspi_regs *ctx = &mcspi->ctx;
        struct omap2_mcspi_cs *cs;
        int error;

        error = pinctrl_pm_select_default_state(dev);
        if (error)
                dev_warn(dev, "%s: failed to set pins: %i\n", __func__, error);

        /* McSPI: context restore */
        mcspi_write_reg(master, OMAP2_MCSPI_MODULCTRL, ctx->modulctrl);
        mcspi_write_reg(master, OMAP2_MCSPI_WAKEUPENABLE, ctx->wakeupenable);

        list_for_each_entry(cs, &ctx->cs, node) {
                /*
                 * We need to toggle CS state for OMAP take this
                 * change in account.
                 */
                if ((cs->chconf0 & OMAP2_MCSPI_CHCONF_FORCE) == 0) {
                        cs->chconf0 |= OMAP2_MCSPI_CHCONF_FORCE;
                        writel_relaxed(cs->chconf0,
                                       cs->base + OMAP2_MCSPI_CHCONF0);
                        cs->chconf0 &= ~OMAP2_MCSPI_CHCONF_FORCE;
                        writel_relaxed(cs->chconf0,
                                       cs->base + OMAP2_MCSPI_CHCONF0);
                } else {
                        writel_relaxed(cs->chconf0,
                                       cs->base + OMAP2_MCSPI_CHCONF0);
                }
        }

        return 0;
}

static struct omap2_mcspi_platform_config omap2_pdata = {
        .regs_offset = 0,
};

static struct omap2_mcspi_platform_config omap4_pdata = {
        .regs_offset = OMAP4_MCSPI_REG_OFFSET,
};

static struct omap2_mcspi_platform_config am654_pdata = {
        .regs_offset = OMAP4_MCSPI_REG_OFFSET,
        .max_xfer_len = SZ_4K - 1,
};

static const struct of_device_id omap_mcspi_of_match[] = {
        {
                .compatible = "ti,omap2-mcspi",
                .data = &omap2_pdata,
        },
        {
                .compatible = "ti,omap4-mcspi",
                .data = &omap4_pdata,
        },
        {
                .compatible = "ti,am654-mcspi",
                .data = &am654_pdata,
        },
        { },
};
MODULE_DEVICE_TABLE(of, omap_mcspi_of_match);

static int omap2_mcspi_probe(struct platform_device *pdev)
{
        struct spi_master       *master;
        const struct omap2_mcspi_platform_config *pdata;
        struct omap2_mcspi      *mcspi;
        struct resource         *r;
        int                     status = 0, i;
        u32                     regs_offset = 0;
        struct device_node      *node = pdev->dev.of_node;
        const struct of_device_id *match;

        if (of_property_read_bool(node, "spi-slave"))
                master = spi_alloc_slave(&pdev->dev, sizeof(*mcspi));
        else
                master = spi_alloc_master(&pdev->dev, sizeof(*mcspi));
        if (!master)
                return -ENOMEM;

        /* the spi->mode bits understood by this driver: */
        master->mode_bits = SPI_CPOL | SPI_CPHA | SPI_CS_HIGH;
        master->bits_per_word_mask = SPI_BPW_RANGE_MASK(4, 32);
        master->setup = omap2_mcspi_setup;
        master->auto_runtime_pm = true;
        master->prepare_message = omap2_mcspi_prepare_message;
        master->can_dma = omap2_mcspi_can_dma;
        master->transfer_one = omap2_mcspi_transfer_one;
        master->set_cs = omap2_mcspi_set_cs;
        master->cleanup = omap2_mcspi_cleanup;
        master->slave_abort = omap2_mcspi_slave_abort;
        master->dev.of_node = node;
        master->max_speed_hz = OMAP2_MCSPI_MAX_FREQ;
        master->min_speed_hz = OMAP2_MCSPI_MAX_FREQ >> 15;
        master->use_gpio_descriptors = true;

        platform_set_drvdata(pdev, master);

        mcspi = spi_master_get_devdata(master);
        mcspi->master = master;

        match = of_match_device(omap_mcspi_of_match, &pdev->dev);
        if (match) {
                u32 num_cs = 1; /* default number of chipselect */
                pdata = match->data;

                of_property_read_u32(node, "ti,spi-num-cs", &num_cs);
                master->num_chipselect = num_cs;
                if (of_get_property(node, "ti,pindir-d0-out-d1-in", NULL))
                        mcspi->pin_dir = MCSPI_PINDIR_D0_OUT_D1_IN;
        } else {
                pdata = dev_get_platdata(&pdev->dev);
                master->num_chipselect = pdata->num_cs;
                mcspi->pin_dir = pdata->pin_dir;
        }
        regs_offset = pdata->regs_offset;
        if (pdata->max_xfer_len) {
                mcspi->max_xfer_len = pdata->max_xfer_len;
                master->max_transfer_size = omap2_mcspi_max_xfer_size;
        }

        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        mcspi->base = devm_ioremap_resource(&pdev->dev, r);
        if (IS_ERR(mcspi->base)) {
                status = PTR_ERR(mcspi->base);
                goto free_master;
        }
        mcspi->phys = r->start + regs_offset;
        mcspi->base += regs_offset;

        mcspi->dev = &pdev->dev;

        INIT_LIST_HEAD(&mcspi->ctx.cs);

        mcspi->dma_channels = devm_kcalloc(&pdev->dev, master->num_chipselect,
                                           sizeof(struct omap2_mcspi_dma),
                                           GFP_KERNEL);
        if (mcspi->dma_channels == NULL) {
                status = -ENOMEM;
                goto free_master;
        }

        for (i = 0; i < master->num_chipselect; i++) {
                sprintf(mcspi->dma_channels[i].dma_rx_ch_name, "rx%d", i);
                sprintf(mcspi->dma_channels[i].dma_tx_ch_name, "tx%d", i);

                status = omap2_mcspi_request_dma(mcspi,
                                                 &mcspi->dma_channels[i]);
                if (status == -EPROBE_DEFER)
                        goto free_master;
        }

        status = platform_get_irq(pdev, 0);
        if (status == -EPROBE_DEFER)
                goto free_master;
        if (status < 0) {
                dev_err(&pdev->dev, "no irq resource found\n");
                goto free_master;
        }
        init_completion(&mcspi->txdone);
        status = devm_request_irq(&pdev->dev, status,
                                  omap2_mcspi_irq_handler, 0, pdev->name,
                                  mcspi);
        if (status) {
                dev_err(&pdev->dev, "Cannot request IRQ");
                goto free_master;
        }

        pm_runtime_use_autosuspend(&pdev->dev);
        pm_runtime_set_autosuspend_delay(&pdev->dev, SPI_AUTOSUSPEND_TIMEOUT);
        pm_runtime_enable(&pdev->dev);

        status = omap2_mcspi_controller_setup(mcspi);
        if (status < 0)
                goto disable_pm;

        status = devm_spi_register_controller(&pdev->dev, master);
        if (status < 0)
                goto disable_pm;

        return status;

disable_pm:
        pm_runtime_dont_use_autosuspend(&pdev->dev);
        pm_runtime_put_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
free_master:
        omap2_mcspi_release_dma(master);
        spi_master_put(master);
        return status;
}

static int omap2_mcspi_remove(struct platform_device *pdev)
{
        struct spi_master *master = platform_get_drvdata(pdev);
        struct omap2_mcspi *mcspi = spi_master_get_devdata(master);

        omap2_mcspi_release_dma(master);

        pm_runtime_dont_use_autosuspend(mcspi->dev);
        pm_runtime_put_sync(mcspi->dev);
        pm_runtime_disable(&pdev->dev);

        return 0;
}

/* work with hotplug and coldplug */
MODULE_ALIAS("platform:omap2_mcspi");

static int __maybe_unused omap2_mcspi_suspend(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct omap2_mcspi *mcspi = spi_master_get_devdata(master);
        int error;

        error = pinctrl_pm_select_sleep_state(dev);
        if (error)
                dev_warn(mcspi->dev, "%s: failed to set pins: %i\n",
                         __func__, error);

        error = spi_master_suspend(master);
        if (error)
                dev_warn(mcspi->dev, "%s: master suspend failed: %i\n",
                         __func__, error);

        return pm_runtime_force_suspend(dev);
}

static int __maybe_unused omap2_mcspi_resume(struct device *dev)
{
        struct spi_master *master = dev_get_drvdata(dev);
        struct omap2_mcspi *mcspi = spi_master_get_devdata(master);
        int error;

        error = spi_master_resume(master);
        if (error)
                dev_warn(mcspi->dev, "%s: master resume failed: %i\n",
                         __func__, error);

        return pm_runtime_force_resume(dev);
}

static const struct dev_pm_ops omap2_mcspi_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(omap2_mcspi_suspend,
                                omap2_mcspi_resume)
        .runtime_suspend        = omap_mcspi_runtime_suspend,
        .runtime_resume         = omap_mcspi_runtime_resume,
};

static struct platform_driver omap2_mcspi_driver = {
        .driver = {
                .name =         "omap2_mcspi",
                .pm =           &omap2_mcspi_pm_ops,
                .of_match_table = omap_mcspi_of_match,
        },
        .probe =        omap2_mcspi_probe,
        .remove =       omap2_mcspi_remove,
};

module_platform_driver(omap2_mcspi_driver);
MODULE_LICENSE("GPL");