linux/drivers/spi/spi-altera.c
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   1/*
   2 * Altera SPI driver
   3 *
   4 * Copyright (C) 2008 Thomas Chou <thomas@wytron.com.tw>
   5 *
   6 * Based on spi_s3c24xx.c, which is:
   7 * Copyright (c) 2006 Ben Dooks
   8 * Copyright (c) 2006 Simtec Electronics
   9 *      Ben Dooks <ben@simtec.co.uk>
  10 *
  11 * This program is free software; you can redistribute it and/or modify
  12 * it under the terms of the GNU General Public License version 2 as
  13 * published by the Free Software Foundation.
  14 */
  15
  16#include <linux/init.h>
  17#include <linux/interrupt.h>
  18#include <linux/errno.h>
  19#include <linux/module.h>
  20#include <linux/platform_device.h>
  21#include <linux/spi/spi.h>
  22#include <linux/spi/spi_bitbang.h>
  23#include <linux/io.h>
  24#include <linux/of.h>
  25
  26#define DRV_NAME "spi_altera"
  27
  28#define ALTERA_SPI_RXDATA       0
  29#define ALTERA_SPI_TXDATA       4
  30#define ALTERA_SPI_STATUS       8
  31#define ALTERA_SPI_CONTROL      12
  32#define ALTERA_SPI_SLAVE_SEL    20
  33
  34#define ALTERA_SPI_STATUS_ROE_MSK       0x8
  35#define ALTERA_SPI_STATUS_TOE_MSK       0x10
  36#define ALTERA_SPI_STATUS_TMT_MSK       0x20
  37#define ALTERA_SPI_STATUS_TRDY_MSK      0x40
  38#define ALTERA_SPI_STATUS_RRDY_MSK      0x80
  39#define ALTERA_SPI_STATUS_E_MSK         0x100
  40
  41#define ALTERA_SPI_CONTROL_IROE_MSK     0x8
  42#define ALTERA_SPI_CONTROL_ITOE_MSK     0x10
  43#define ALTERA_SPI_CONTROL_ITRDY_MSK    0x40
  44#define ALTERA_SPI_CONTROL_IRRDY_MSK    0x80
  45#define ALTERA_SPI_CONTROL_IE_MSK       0x100
  46#define ALTERA_SPI_CONTROL_SSO_MSK      0x400
  47
  48struct altera_spi {
  49        /* bitbang has to be first */
  50        struct spi_bitbang bitbang;
  51        struct completion done;
  52
  53        void __iomem *base;
  54        int irq;
  55        int len;
  56        int count;
  57        int bytes_per_word;
  58        unsigned long imr;
  59
  60        /* data buffers */
  61        const unsigned char *tx;
  62        unsigned char *rx;
  63};
  64
  65static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
  66{
  67        return spi_master_get_devdata(sdev->master);
  68}
  69
  70static void altera_spi_chipsel(struct spi_device *spi, int value)
  71{
  72        struct altera_spi *hw = altera_spi_to_hw(spi);
  73
  74        if (spi->mode & SPI_CS_HIGH) {
  75                switch (value) {
  76                case BITBANG_CS_INACTIVE:
  77                        writel(1 << spi->chip_select,
  78                               hw->base + ALTERA_SPI_SLAVE_SEL);
  79                        hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
  80                        writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
  81                        break;
  82
  83                case BITBANG_CS_ACTIVE:
  84                        hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
  85                        writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
  86                        writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
  87                        break;
  88                }
  89        } else {
  90                switch (value) {
  91                case BITBANG_CS_INACTIVE:
  92                        hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
  93                        writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
  94                        break;
  95
  96                case BITBANG_CS_ACTIVE:
  97                        writel(1 << spi->chip_select,
  98                               hw->base + ALTERA_SPI_SLAVE_SEL);
  99                        hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
 100                        writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 101                        break;
 102                }
 103        }
 104}
 105
 106static int altera_spi_setupxfer(struct spi_device *spi, struct spi_transfer *t)
 107{
 108        return 0;
 109}
 110
 111static int altera_spi_setup(struct spi_device *spi)
 112{
 113        return 0;
 114}
 115
 116static inline unsigned int hw_txbyte(struct altera_spi *hw, int count)
 117{
 118        if (hw->tx) {
 119                switch (hw->bytes_per_word) {
 120                case 1:
 121                        return hw->tx[count];
 122                case 2:
 123                        return (hw->tx[count * 2]
 124                                | (hw->tx[count * 2 + 1] << 8));
 125                }
 126        }
 127        return 0;
 128}
 129
 130static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
 131{
 132        struct altera_spi *hw = altera_spi_to_hw(spi);
 133
 134        hw->tx = t->tx_buf;
 135        hw->rx = t->rx_buf;
 136        hw->count = 0;
 137        hw->bytes_per_word = (t->bits_per_word ? : spi->bits_per_word) / 8;
 138        hw->len = t->len / hw->bytes_per_word;
 139
 140        if (hw->irq >= 0) {
 141                /* enable receive interrupt */
 142                hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
 143                writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 144
 145                /* send the first byte */
 146                writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
 147
 148                wait_for_completion(&hw->done);
 149                /* disable receive interrupt */
 150                hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
 151                writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 152        } else {
 153                /* send the first byte */
 154                writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
 155
 156                while (1) {
 157                        unsigned int rxd;
 158
 159                        while (!(readl(hw->base + ALTERA_SPI_STATUS) &
 160                                 ALTERA_SPI_STATUS_RRDY_MSK))
 161                                cpu_relax();
 162
 163                        rxd = readl(hw->base + ALTERA_SPI_RXDATA);
 164                        if (hw->rx) {
 165                                switch (hw->bytes_per_word) {
 166                                case 1:
 167                                        hw->rx[hw->count] = rxd;
 168                                        break;
 169                                case 2:
 170                                        hw->rx[hw->count * 2] = rxd;
 171                                        hw->rx[hw->count * 2 + 1] = rxd >> 8;
 172                                        break;
 173                                }
 174                        }
 175
 176                        hw->count++;
 177
 178                        if (hw->count < hw->len)
 179                                writel(hw_txbyte(hw, hw->count),
 180                                       hw->base + ALTERA_SPI_TXDATA);
 181                        else
 182                                break;
 183                }
 184
 185        }
 186
 187        return hw->count * hw->bytes_per_word;
 188}
 189
 190static irqreturn_t altera_spi_irq(int irq, void *dev)
 191{
 192        struct altera_spi *hw = dev;
 193        unsigned int rxd;
 194
 195        rxd = readl(hw->base + ALTERA_SPI_RXDATA);
 196        if (hw->rx) {
 197                switch (hw->bytes_per_word) {
 198                case 1:
 199                        hw->rx[hw->count] = rxd;
 200                        break;
 201                case 2:
 202                        hw->rx[hw->count * 2] = rxd;
 203                        hw->rx[hw->count * 2 + 1] = rxd >> 8;
 204                        break;
 205                }
 206        }
 207
 208        hw->count++;
 209
 210        if (hw->count < hw->len)
 211                writel(hw_txbyte(hw, hw->count), hw->base + ALTERA_SPI_TXDATA);
 212        else
 213                complete(&hw->done);
 214
 215        return IRQ_HANDLED;
 216}
 217
 218static int altera_spi_probe(struct platform_device *pdev)
 219{
 220        struct altera_spi_platform_data *platp = pdev->dev.platform_data;
 221        struct altera_spi *hw;
 222        struct spi_master *master;
 223        struct resource *res;
 224        int err = -ENODEV;
 225
 226        master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
 227        if (!master)
 228                return err;
 229
 230        /* setup the master state. */
 231        master->bus_num = pdev->id;
 232        master->num_chipselect = 16;
 233        master->mode_bits = SPI_CS_HIGH;
 234        master->setup = altera_spi_setup;
 235
 236        hw = spi_master_get_devdata(master);
 237        platform_set_drvdata(pdev, hw);
 238
 239        /* setup the state for the bitbang driver */
 240        hw->bitbang.master = spi_master_get(master);
 241        if (!hw->bitbang.master)
 242                return err;
 243        hw->bitbang.setup_transfer = altera_spi_setupxfer;
 244        hw->bitbang.chipselect = altera_spi_chipsel;
 245        hw->bitbang.txrx_bufs = altera_spi_txrx;
 246
 247        /* find and map our resources */
 248        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 249        if (!res)
 250                goto exit_busy;
 251        if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
 252                                     pdev->name))
 253                goto exit_busy;
 254        hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
 255                                        resource_size(res));
 256        if (!hw->base)
 257                goto exit_busy;
 258        /* program defaults into the registers */
 259        hw->imr = 0;            /* disable spi interrupts */
 260        writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
 261        writel(0, hw->base + ALTERA_SPI_STATUS);        /* clear status reg */
 262        if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
 263                readl(hw->base + ALTERA_SPI_RXDATA);    /* flush rxdata */
 264        /* irq is optional */
 265        hw->irq = platform_get_irq(pdev, 0);
 266        if (hw->irq >= 0) {
 267                init_completion(&hw->done);
 268                err = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
 269                                       pdev->name, hw);
 270                if (err)
 271                        goto exit;
 272        }
 273        /* find platform data */
 274        if (!platp)
 275                hw->bitbang.master->dev.of_node = pdev->dev.of_node;
 276
 277        /* register our spi controller */
 278        err = spi_bitbang_start(&hw->bitbang);
 279        if (err)
 280                goto exit;
 281        dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
 282
 283        return 0;
 284
 285exit_busy:
 286        err = -EBUSY;
 287exit:
 288        platform_set_drvdata(pdev, NULL);
 289        spi_master_put(master);
 290        return err;
 291}
 292
 293static int altera_spi_remove(struct platform_device *dev)
 294{
 295        struct altera_spi *hw = platform_get_drvdata(dev);
 296        struct spi_master *master = hw->bitbang.master;
 297
 298        spi_bitbang_stop(&hw->bitbang);
 299        platform_set_drvdata(dev, NULL);
 300        spi_master_put(master);
 301        return 0;
 302}
 303
 304#ifdef CONFIG_OF
 305static const struct of_device_id altera_spi_match[] = {
 306        { .compatible = "ALTR,spi-1.0", },
 307        {},
 308};
 309MODULE_DEVICE_TABLE(of, altera_spi_match);
 310#endif /* CONFIG_OF */
 311
 312static struct platform_driver altera_spi_driver = {
 313        .probe = altera_spi_probe,
 314        .remove = altera_spi_remove,
 315        .driver = {
 316                .name = DRV_NAME,
 317                .owner = THIS_MODULE,
 318                .pm = NULL,
 319                .of_match_table = of_match_ptr(altera_spi_match),
 320        },
 321};
 322module_platform_driver(altera_spi_driver);
 323
 324MODULE_DESCRIPTION("Altera SPI driver");
 325MODULE_AUTHOR("Thomas Chou <thomas@wytron.com.tw>");
 326MODULE_LICENSE("GPL");
 327MODULE_ALIAS("platform:" DRV_NAME);
 328
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