linux/drivers/spi/spi-ath79.c
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   1/*
   2 * SPI controller driver for the Atheros AR71XX/AR724X/AR913X SoCs
   3 *
   4 * Copyright (C) 2009-2011 Gabor Juhos <juhosg@openwrt.org>
   5 *
   6 * This driver has been based on the spi-gpio.c:
   7 *      Copyright (C) 2006,2008 David Brownell
   8 *
   9 * This program is free software; you can redistribute it and/or modify
  10 * it under the terms of the GNU General Public License version 2 as
  11 * published by the Free Software Foundation.
  12 *
  13 */
  14
  15#include <linux/kernel.h>
  16#include <linux/module.h>
  17#include <linux/init.h>
  18#include <linux/delay.h>
  19#include <linux/spinlock.h>
  20#include <linux/workqueue.h>
  21#include <linux/platform_device.h>
  22#include <linux/io.h>
  23#include <linux/spi/spi.h>
  24#include <linux/spi/spi_bitbang.h>
  25#include <linux/bitops.h>
  26#include <linux/gpio.h>
  27#include <linux/clk.h>
  28#include <linux/err.h>
  29
  30#include <asm/mach-ath79/ar71xx_regs.h>
  31#include <asm/mach-ath79/ath79_spi_platform.h>
  32
  33#define DRV_NAME        "ath79-spi"
  34
  35#define ATH79_SPI_RRW_DELAY_FACTOR      12000
  36#define MHZ                             (1000 * 1000)
  37
  38struct ath79_spi {
  39        struct spi_bitbang      bitbang;
  40        u32                     ioc_base;
  41        u32                     reg_ctrl;
  42        void __iomem            *base;
  43        struct clk              *clk;
  44        unsigned                rrw_delay;
  45};
  46
  47static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg)
  48{
  49        return ioread32(sp->base + reg);
  50}
  51
  52static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned reg, u32 val)
  53{
  54        iowrite32(val, sp->base + reg);
  55}
  56
  57static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
  58{
  59        return spi_master_get_devdata(spi->master);
  60}
  61
  62static inline void ath79_spi_delay(struct ath79_spi *sp, unsigned nsecs)
  63{
  64        if (nsecs > sp->rrw_delay)
  65                ndelay(nsecs - sp->rrw_delay);
  66}
  67
  68static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
  69{
  70        struct ath79_spi *sp = ath79_spidev_to_sp(spi);
  71        int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;
  72
  73        if (is_active) {
  74                /* set initial clock polarity */
  75                if (spi->mode & SPI_CPOL)
  76                        sp->ioc_base |= AR71XX_SPI_IOC_CLK;
  77                else
  78                        sp->ioc_base &= ~AR71XX_SPI_IOC_CLK;
  79
  80                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
  81        }
  82
  83        if (spi->chip_select) {
  84                struct ath79_spi_controller_data *cdata = spi->controller_data;
  85
  86                /* SPI is normally active-low */
  87                gpio_set_value(cdata->gpio, cs_high);
  88        } else {
  89                if (cs_high)
  90                        sp->ioc_base |= AR71XX_SPI_IOC_CS0;
  91                else
  92                        sp->ioc_base &= ~AR71XX_SPI_IOC_CS0;
  93
  94                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
  95        }
  96
  97}
  98
  99static void ath79_spi_enable(struct ath79_spi *sp)
 100{
 101        /* enable GPIO mode */
 102        ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
 103
 104        /* save CTRL register */
 105        sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
 106        sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);
 107
 108        /* TODO: setup speed? */
 109        ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);
 110}
 111
 112static void ath79_spi_disable(struct ath79_spi *sp)
 113{
 114        /* restore CTRL register */
 115        ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
 116        /* disable GPIO mode */
 117        ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
 118}
 119
 120static int ath79_spi_setup_cs(struct spi_device *spi)
 121{
 122        struct ath79_spi_controller_data *cdata;
 123        int status;
 124
 125        cdata = spi->controller_data;
 126        if (spi->chip_select && !cdata)
 127                return -EINVAL;
 128
 129        status = 0;
 130        if (spi->chip_select) {
 131                unsigned long flags;
 132
 133                flags = GPIOF_DIR_OUT;
 134                if (spi->mode & SPI_CS_HIGH)
 135                        flags |= GPIOF_INIT_HIGH;
 136                else
 137                        flags |= GPIOF_INIT_LOW;
 138
 139                status = gpio_request_one(cdata->gpio, flags,
 140                                          dev_name(&spi->dev));
 141        }
 142
 143        return status;
 144}
 145
 146static void ath79_spi_cleanup_cs(struct spi_device *spi)
 147{
 148        if (spi->chip_select) {
 149                struct ath79_spi_controller_data *cdata = spi->controller_data;
 150                gpio_free(cdata->gpio);
 151        }
 152}
 153
 154static int ath79_spi_setup(struct spi_device *spi)
 155{
 156        int status = 0;
 157
 158        if (spi->bits_per_word > 32)
 159                return -EINVAL;
 160
 161        if (!spi->controller_state) {
 162                status = ath79_spi_setup_cs(spi);
 163                if (status)
 164                        return status;
 165        }
 166
 167        status = spi_bitbang_setup(spi);
 168        if (status && !spi->controller_state)
 169                ath79_spi_cleanup_cs(spi);
 170
 171        return status;
 172}
 173
 174static void ath79_spi_cleanup(struct spi_device *spi)
 175{
 176        ath79_spi_cleanup_cs(spi);
 177        spi_bitbang_cleanup(spi);
 178}
 179
 180static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
 181                               u32 word, u8 bits)
 182{
 183        struct ath79_spi *sp = ath79_spidev_to_sp(spi);
 184        u32 ioc = sp->ioc_base;
 185
 186        /* clock starts at inactive polarity */
 187        for (word <<= (32 - bits); likely(bits); bits--) {
 188                u32 out;
 189
 190                if (word & (1 << 31))
 191                        out = ioc | AR71XX_SPI_IOC_DO;
 192                else
 193                        out = ioc & ~AR71XX_SPI_IOC_DO;
 194
 195                /* setup MSB (to slave) on trailing edge */
 196                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
 197                ath79_spi_delay(sp, nsecs);
 198                ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
 199                ath79_spi_delay(sp, nsecs);
 200                if (bits == 1)
 201                        ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
 202
 203                word <<= 1;
 204        }
 205
 206        return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
 207}
 208
 209static int ath79_spi_probe(struct platform_device *pdev)
 210{
 211        struct spi_master *master;
 212        struct ath79_spi *sp;
 213        struct ath79_spi_platform_data *pdata;
 214        struct resource *r;
 215        unsigned long rate;
 216        int ret;
 217
 218        master = spi_alloc_master(&pdev->dev, sizeof(*sp));
 219        if (master == NULL) {
 220                dev_err(&pdev->dev, "failed to allocate spi master\n");
 221                return -ENOMEM;
 222        }
 223
 224        sp = spi_master_get_devdata(master);
 225        platform_set_drvdata(pdev, sp);
 226
 227        pdata = pdev->dev.platform_data;
 228
 229        master->setup = ath79_spi_setup;
 230        master->cleanup = ath79_spi_cleanup;
 231        if (pdata) {
 232                master->bus_num = pdata->bus_num;
 233                master->num_chipselect = pdata->num_chipselect;
 234        }
 235
 236        sp->bitbang.master = spi_master_get(master);
 237        sp->bitbang.chipselect = ath79_spi_chipselect;
 238        sp->bitbang.txrx_word[SPI_MODE_0] = ath79_spi_txrx_mode0;
 239        sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;
 240        sp->bitbang.flags = SPI_CS_HIGH;
 241
 242        r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 243        if (r == NULL) {
 244                ret = -ENOENT;
 245                goto err_put_master;
 246        }
 247
 248        sp->base = ioremap(r->start, resource_size(r));
 249        if (!sp->base) {
 250                ret = -ENXIO;
 251                goto err_put_master;
 252        }
 253
 254        sp->clk = clk_get(&pdev->dev, "ahb");
 255        if (IS_ERR(sp->clk)) {
 256                ret = PTR_ERR(sp->clk);
 257                goto err_unmap;
 258        }
 259
 260        ret = clk_enable(sp->clk);
 261        if (ret)
 262                goto err_clk_put;
 263
 264        rate = DIV_ROUND_UP(clk_get_rate(sp->clk), MHZ);
 265        if (!rate) {
 266                ret = -EINVAL;
 267                goto err_clk_disable;
 268        }
 269
 270        sp->rrw_delay = ATH79_SPI_RRW_DELAY_FACTOR / rate;
 271        dev_dbg(&pdev->dev, "register read/write delay is %u nsecs\n",
 272                sp->rrw_delay);
 273
 274        ath79_spi_enable(sp);
 275        ret = spi_bitbang_start(&sp->bitbang);
 276        if (ret)
 277                goto err_disable;
 278
 279        return 0;
 280
 281err_disable:
 282        ath79_spi_disable(sp);
 283err_clk_disable:
 284        clk_disable(sp->clk);
 285err_clk_put:
 286        clk_put(sp->clk);
 287err_unmap:
 288        iounmap(sp->base);
 289err_put_master:
 290        platform_set_drvdata(pdev, NULL);
 291        spi_master_put(sp->bitbang.master);
 292
 293        return ret;
 294}
 295
 296static int ath79_spi_remove(struct platform_device *pdev)
 297{
 298        struct ath79_spi *sp = platform_get_drvdata(pdev);
 299
 300        spi_bitbang_stop(&sp->bitbang);
 301        ath79_spi_disable(sp);
 302        clk_disable(sp->clk);
 303        clk_put(sp->clk);
 304        iounmap(sp->base);
 305        platform_set_drvdata(pdev, NULL);
 306        spi_master_put(sp->bitbang.master);
 307
 308        return 0;
 309}
 310
 311static void ath79_spi_shutdown(struct platform_device *pdev)
 312{
 313        ath79_spi_remove(pdev);
 314}
 315
 316static struct platform_driver ath79_spi_driver = {
 317        .probe          = ath79_spi_probe,
 318        .remove         = ath79_spi_remove,
 319        .shutdown       = ath79_spi_shutdown,
 320        .driver         = {
 321                .name   = DRV_NAME,
 322                .owner  = THIS_MODULE,
 323        },
 324};
 325module_platform_driver(ath79_spi_driver);
 326
 327MODULE_DESCRIPTION("SPI controller driver for Atheros AR71XX/AR724X/AR913X");
 328MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 329MODULE_LICENSE("GPL v2");
 330MODULE_ALIAS("platform:" DRV_NAME);
 331
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