drivers/spi/spi-ath79.c

   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/delay.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/io.h>
  21 #include <linux/spi/spi.h>
  22 #include <linux/spi/spi_bitbang.h>
  23 #include <linux/bitops.h>
  24 #include <linux/gpio.h>
  25 #include <linux/clk.h>
  26 #include <linux/err.h>
  27
  28 #include <asm/mach-ath79/ar71xx_regs.h>
  29 #include <asm/mach-ath79/ath79_spi_platform.h>
  30
  31 #define DRV_NAME        "ath79-spi"
  32
  33 #define ATH79_SPI_RRW_DELAY_FACTOR      12000
  34 #define MHZ                             (1000 * 1000)
  35
  36 struct ath79_spi {
  37         struct spi_bitbang      bitbang;
  38         u32                     ioc_base;
  39         u32                     reg_ctrl;
  40         void __iomem            *base;
  41         struct clk              *clk;
  42         unsigned                rrw_delay;
  43 };
  44
  45 static inline u32 ath79_spi_rr(struct ath79_spi *sp, unsigned reg)
  46 {
  47         return ioread32(sp->base + reg);
  48 }
  49
  50 static inline void ath79_spi_wr(struct ath79_spi *sp, unsigned reg, u32 val)
  51 {
  52         iowrite32(val, sp->base + reg);
  53 }
  54
  55 static inline struct ath79_spi *ath79_spidev_to_sp(struct spi_device *spi)
  56 {
  57         return spi_master_get_devdata(spi->master);
  58 }
  59
  60 static inline void ath79_spi_delay(struct ath79_spi *sp, unsigned nsecs)
  61 {
  62         if (nsecs > sp->rrw_delay)
  63                 ndelay(nsecs - sp->rrw_delay);
  64 }
  65
  66 static void ath79_spi_chipselect(struct spi_device *spi, int is_active)
  67 {
  68         struct ath79_spi *sp = ath79_spidev_to_sp(spi);
  69         int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;
  70
  71         if (is_active) {
  72                 /* set initial clock polarity */
  73                 if (spi->mode & SPI_CPOL)
  74                         sp->ioc_base |= AR71XX_SPI_IOC_CLK;
  75                 else
  76                         sp->ioc_base &= ~AR71XX_SPI_IOC_CLK;
  77
  78                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
  79         }
  80
  81         if (spi->chip_select) {
  82                 /* SPI is normally active-low */
  83                 gpio_set_value(spi->cs_gpio, cs_high);
  84         } else {
  85                 if (cs_high)
  86                         sp->ioc_base |= AR71XX_SPI_IOC_CS0;
  87                 else
  88                         sp->ioc_base &= ~AR71XX_SPI_IOC_CS0;
  89
  90                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
  91         }
  92
  93 }
  94
  95 static void ath79_spi_enable(struct ath79_spi *sp)
  96 {
  97         /* enable GPIO mode */
  98         ath79_spi_wr(sp, AR71XX_SPI_REG_FS, AR71XX_SPI_FS_GPIO);
  99
 100         /* save CTRL register */
 101         sp->reg_ctrl = ath79_spi_rr(sp, AR71XX_SPI_REG_CTRL);
 102         sp->ioc_base = ath79_spi_rr(sp, AR71XX_SPI_REG_IOC);
 103
 104         /* TODO: setup speed? */
 105         ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, 0x43);
 106 }
 107
 108 static void ath79_spi_disable(struct ath79_spi *sp)
 109 {
 110         /* restore CTRL register */
 111         ath79_spi_wr(sp, AR71XX_SPI_REG_CTRL, sp->reg_ctrl);
 112         /* disable GPIO mode */
 113         ath79_spi_wr(sp, AR71XX_SPI_REG_FS, 0);
 114 }
 115
 116 static int ath79_spi_setup_cs(struct spi_device *spi)
 117 {
 118         struct ath79_spi *sp = ath79_spidev_to_sp(spi);
 119         int status;
 120
 121         if (spi->chip_select && !gpio_is_valid(spi->cs_gpio))
 122                 return -EINVAL;
 123
 124         status = 0;
 125         if (spi->chip_select) {
 126                 unsigned long flags;
 127
 128                 flags = GPIOF_DIR_OUT;
 129                 if (spi->mode & SPI_CS_HIGH)
 130                         flags |= GPIOF_INIT_LOW;
 131                 else
 132                         flags |= GPIOF_INIT_HIGH;
 133
 134                 status = gpio_request_one(spi->cs_gpio, flags,
 135                                           dev_name(&spi->dev));
 136         } else {
 137                 if (spi->mode & SPI_CS_HIGH)
 138                         sp->ioc_base &= ~AR71XX_SPI_IOC_CS0;
 139                 else
 140                         sp->ioc_base |= AR71XX_SPI_IOC_CS0;
 141
 142                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, sp->ioc_base);
 143         }
 144
 145         return status;
 146 }
 147
 148 static void ath79_spi_cleanup_cs(struct spi_device *spi)
 149 {
 150         if (spi->chip_select) {
 151                 gpio_free(spi->cs_gpio);
 152         }
 153 }
 154
 155 static int ath79_spi_setup(struct spi_device *spi)
 156 {
 157         int status = 0;
 158
 159         if (!spi->controller_state) {
 160                 status = ath79_spi_setup_cs(spi);
 161                 if (status)
 162                         return status;
 163         }
 164
 165         status = spi_bitbang_setup(spi);
 166         if (status && !spi->controller_state)
 167                 ath79_spi_cleanup_cs(spi);
 168
 169         return status;
 170 }
 171
 172 static void ath79_spi_cleanup(struct spi_device *spi)
 173 {
 174         ath79_spi_cleanup_cs(spi);
 175         spi_bitbang_cleanup(spi);
 176 }
 177
 178 static u32 ath79_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
 179                                u32 word, u8 bits)
 180 {
 181         struct ath79_spi *sp = ath79_spidev_to_sp(spi);
 182         u32 ioc = sp->ioc_base;
 183
 184         /* clock starts at inactive polarity */
 185         for (word <<= (32 - bits); likely(bits); bits--) {
 186                 u32 out;
 187
 188                 if (word & (1 << 31))
 189                         out = ioc | AR71XX_SPI_IOC_DO;
 190                 else
 191                         out = ioc & ~AR71XX_SPI_IOC_DO;
 192
 193                 /* setup MSB (to slave) on trailing edge */
 194                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
 195                 ath79_spi_delay(sp, nsecs);
 196                 ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out | AR71XX_SPI_IOC_CLK);
 197                 ath79_spi_delay(sp, nsecs);
 198                 if (bits == 1)
 199                         ath79_spi_wr(sp, AR71XX_SPI_REG_IOC, out);
 200
 201                 word <<= 1;
 202         }
 203
 204         return ath79_spi_rr(sp, AR71XX_SPI_REG_RDS);
 205 }
 206
 207 static int ath79_spi_probe(struct platform_device *pdev)
 208 {
 209         struct spi_master *master;
 210         struct ath79_spi *sp;
 211         struct ath79_spi_platform_data *pdata;
 212         struct resource *r;
 213         unsigned long rate;
 214         int ret;
 215
 216         master = spi_alloc_master(&pdev->dev, sizeof(*sp));
 217         if (master == NULL) {
 218                 dev_err(&pdev->dev, "failed to allocate spi master\n");
 219                 return -ENOMEM;
 220         }
 221
 222         sp = spi_master_get_devdata(master);
 223         master->dev.of_node = pdev->dev.of_node;
 224         platform_set_drvdata(pdev, sp);
 225
 226         pdata = dev_get_platdata(&pdev->dev);
 227
 228         master->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32);
 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 = 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         sp->base = devm_ioremap_resource(&pdev->dev, r);
 244         if (IS_ERR(sp->base)) {
 245                 ret = PTR_ERR(sp->base);
 246                 goto err_put_master;
 247         }
 248
 249         sp->clk = devm_clk_get(&pdev->dev, "ahb");
 250         if (IS_ERR(sp->clk)) {
 251                 ret = PTR_ERR(sp->clk);
 252                 goto err_put_master;
 253         }
 254
 255         ret = clk_prepare_enable(sp->clk);
 256         if (ret)
 257                 goto err_put_master;
 258
 259         rate = DIV_ROUND_UP(clk_get_rate(sp->clk), MHZ);
 260         if (!rate) {
 261                 ret = -EINVAL;
 262                 goto err_clk_disable;
 263         }
 264
 265         sp->rrw_delay = ATH79_SPI_RRW_DELAY_FACTOR / rate;
 266         dev_dbg(&pdev->dev, "register read/write delay is %u nsecs\n",
 267                 sp->rrw_delay);
 268
 269         ath79_spi_enable(sp);
 270         ret = spi_bitbang_start(&sp->bitbang);
 271         if (ret)
 272                 goto err_disable;
 273
 274         return 0;
 275
 276 err_disable:
 277         ath79_spi_disable(sp);
 278 err_clk_disable:
 279         clk_disable_unprepare(sp->clk);
 280 err_put_master:
 281         spi_master_put(sp->bitbang.master);
 282
 283         return ret;
 284 }
 285
 286 static int ath79_spi_remove(struct platform_device *pdev)
 287 {
 288         struct ath79_spi *sp = platform_get_drvdata(pdev);
 289
 290         spi_bitbang_stop(&sp->bitbang);
 291         ath79_spi_disable(sp);
 292         clk_disable_unprepare(sp->clk);
 293         spi_master_put(sp->bitbang.master);
 294
 295         return 0;
 296 }
 297
 298 static void ath79_spi_shutdown(struct platform_device *pdev)
 299 {
 300         ath79_spi_remove(pdev);
 301 }
 302
 303 static const struct of_device_id ath79_spi_of_match[] = {
 304         { .compatible = "qca,ar7100-spi", },
 305         { },
 306 };
 307
 308 static struct platform_driver ath79_spi_driver = {
 309         .probe          = ath79_spi_probe,
 310         .remove         = ath79_spi_remove,
 311         .shutdown       = ath79_spi_shutdown,
 312         .driver         = {
 313                 .name   = DRV_NAME,
 314                 .of_match_table = ath79_spi_of_match,
 315         },
 316 };
 317 module_platform_driver(ath79_spi_driver);
 318
 319 MODULE_DESCRIPTION("SPI controller driver for Atheros AR71XX/AR724X/AR913X");
 320 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 321 MODULE_LICENSE("GPL v2");
 322 MODULE_ALIAS("platform:" DRV_NAME);