target/linux/ar71xx/files/drivers/spi/ar71xx_spi.c

   1 /*
   2  * Atheros AR71xx SPI Controller driver
   3  *
   4  * Copyright (C) 2008-2009 Gabor Juhos <juhosg@openwrt.org>
   5  * Copyright (C) 2008 Imre Kaloz <kaloz@openwrt.org>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License version 2 as
   9  * published by the Free Software Foundation.
  10  *
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/init.h>
  15 #include <linux/delay.h>
  16 #include <linux/spinlock.h>
  17 #include <linux/workqueue.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/io.h>
  20 #include <linux/spi/spi.h>
  21 #include <linux/spi/spi_bitbang.h>
  22 #include <linux/bitops.h>
  23
  24 #include <asm/mach-ar71xx/ar71xx.h>
  25 #include <asm/mach-ar71xx/platform.h>
  26
  27 #define DRV_DESC        "Atheros AR71xx SPI Controller driver"
  28 #define DRV_VERSION     "0.2.4"
  29 #define DRV_NAME        "ar71xx-spi"
  30
  31 #undef PER_BIT_READ
  32
  33 struct ar71xx_spi {
  34         struct  spi_bitbang     bitbang;
  35         u32                     ioc_base;
  36         u32                     reg_ctrl;
  37
  38         void __iomem            *base;
  39
  40         struct platform_device  *pdev;
  41         u32                     (*get_ioc_base)(u8 chip_select, int cs_high,
  42                                                 int is_on);
  43 };
  44
  45 static inline u32 ar71xx_spi_rr(struct ar71xx_spi *sp, unsigned reg)
  46 {
  47         return __raw_readl(sp->base + reg);
  48 }
  49
  50 static inline void ar71xx_spi_wr(struct ar71xx_spi *sp, unsigned reg, u32 val)
  51 {
  52         __raw_writel(val, sp->base + reg);
  53 }
  54
  55 static inline struct ar71xx_spi *spidev_to_sp(struct spi_device *spi)
  56 {
  57         return spi_master_get_devdata(spi->master);
  58 }
  59
  60 static u32 ar71xx_spi_get_ioc_base(u8 chip_select, int cs_high, int is_on)
  61 {
  62         u32 ret;
  63
  64         if (is_on == AR71XX_SPI_CS_INACTIVE)
  65                 ret = SPI_IOC_CS_ALL;
  66         else
  67                 ret = SPI_IOC_CS_ALL & ~SPI_IOC_CS(chip_select);
  68
  69         return ret;
  70 }
  71
  72 static void ar71xx_spi_chipselect(struct spi_device *spi, int value)
  73 {
  74         struct ar71xx_spi *sp = spidev_to_sp(spi);
  75         void __iomem *base = sp->base;
  76         u32 ioc_base;
  77
  78         switch (value) {
  79         case BITBANG_CS_INACTIVE:
  80                 ioc_base = sp->get_ioc_base(spi->chip_select,
  81                                         (spi->mode & SPI_CS_HIGH) != 0,
  82                                         AR71XX_SPI_CS_INACTIVE);
  83                 __raw_writel(ioc_base, base + SPI_REG_IOC);
  84                 break;
  85
  86         case BITBANG_CS_ACTIVE:
  87                 ioc_base = sp->get_ioc_base(spi->chip_select,
  88                                         (spi->mode & SPI_CS_HIGH) != 0,
  89                                         AR71XX_SPI_CS_ACTIVE);
  90
  91                 __raw_writel(ioc_base, base + SPI_REG_IOC);
  92                 sp->ioc_base = ioc_base;
  93                 break;
  94         }
  95 }
  96
  97 static void ar71xx_spi_setup_regs(struct ar71xx_spi *sp)
  98 {
  99         /* enable GPIO mode */
 100         ar71xx_spi_wr(sp, SPI_REG_FS, SPI_FS_GPIO);
 101
 102         /* save CTRL register */
 103         sp->reg_ctrl = ar71xx_spi_rr(sp, SPI_REG_CTRL);
 104
 105         /* TODO: setup speed? */
 106         ar71xx_spi_wr(sp, SPI_REG_CTRL, 0x43);
 107 }
 108
 109 static void ar71xx_spi_restore_regs(struct ar71xx_spi *sp)
 110 {
 111         /* restore CTRL register */
 112         ar71xx_spi_wr(sp, SPI_REG_CTRL, sp->reg_ctrl);
 113         /* disable GPIO mode */
 114         ar71xx_spi_wr(sp, SPI_REG_FS, 0);
 115 }
 116
 117 static int ar71xx_spi_setup(struct spi_device *spi)
 118 {
 119         if (spi->bits_per_word > 32)
 120                 return -EINVAL;
 121
 122         return spi_bitbang_setup(spi);
 123 }
 124
 125 static void ar71xx_spi_cleanup(struct spi_device *spi)
 126 {
 127         spi_bitbang_cleanup(spi);
 128 }
 129
 130 static u32 ar71xx_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
 131                                         u32 word, u8 bits)
 132 {
 133         struct ar71xx_spi *sp = spidev_to_sp(spi);
 134         void __iomem *base = sp->base;
 135         u32 ioc = sp->ioc_base;
 136         u32 ret;
 137
 138         /* clock starts at inactive polarity */
 139         for (word <<= (32 - bits); likely(bits); bits--) {
 140                 u32 out;
 141
 142                 if (word & (1 << 31))
 143                         out = ioc | SPI_IOC_DO;
 144                 else
 145                         out = ioc & ~SPI_IOC_DO;
 146
 147                 /* setup MSB (to slave) on trailing edge */
 148                 __raw_writel(out, base + SPI_REG_IOC);
 149
 150                 __raw_writel(out | SPI_IOC_CLK, base + SPI_REG_IOC);
 151
 152                 word <<= 1;
 153
 154 #ifdef PER_BIT_READ
 155                 /* sample MSB (from slave) on leading edge */
 156                 ret = __raw_readl(base + SPI_REG_RDS);
 157                 __raw_writel(out, base + SPI_REG_IOC);
 158 #endif
 159
 160         }
 161
 162 #ifndef PER_BIT_READ
 163         ret = __raw_readl(base + SPI_REG_RDS);
 164 #endif
 165         return ret;
 166 }
 167
 168 static int ar71xx_spi_probe(struct platform_device *pdev)
 169 {
 170         struct spi_master *master;
 171         struct ar71xx_spi *sp;
 172         struct ar71xx_spi_platform_data *pdata;
 173         struct resource *r;
 174         int ret;
 175
 176         master = spi_alloc_master(&pdev->dev, sizeof(*sp));
 177         if (master == NULL) {
 178                 dev_err(&pdev->dev, "failed to allocate spi master\n");
 179                 return -ENOMEM;
 180         }
 181
 182         sp = spi_master_get_devdata(master);
 183         platform_set_drvdata(pdev, sp);
 184
 185         pdata = pdev->dev.platform_data;
 186
 187         master->setup = ar71xx_spi_setup;
 188         master->cleanup = ar71xx_spi_cleanup;
 189
 190         sp->bitbang.master = spi_master_get(master);
 191         sp->bitbang.chipselect = ar71xx_spi_chipselect;
 192         sp->bitbang.txrx_word[SPI_MODE_0] = ar71xx_spi_txrx_mode0;
 193         sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;
 194
 195         sp->get_ioc_base = ar71xx_spi_get_ioc_base;
 196         if (pdata) {
 197                 sp->bitbang.master->bus_num = pdata->bus_num;
 198                 sp->bitbang.master->num_chipselect = pdata->num_chipselect;
 199                 if (pdata->get_ioc_base)
 200                         sp->get_ioc_base = pdata->get_ioc_base;
 201         } else {
 202                 sp->bitbang.master->bus_num = 0;
 203                 sp->bitbang.master->num_chipselect = 3;
 204         }
 205
 206         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 207         if (r == NULL) {
 208                 ret = -ENOENT;
 209                 goto err1;
 210         }
 211
 212         sp->base = ioremap_nocache(r->start, r->end - r->start + 1);
 213         if (!sp->base) {
 214                 ret = -ENXIO;
 215                 goto err1;
 216         }
 217
 218         ar71xx_spi_setup_regs(sp);
 219
 220         ret = spi_bitbang_start(&sp->bitbang);
 221         if (!ret)
 222                 return 0;
 223
 224         ar71xx_spi_restore_regs(sp);
 225         iounmap(sp->base);
 226 err1:
 227         platform_set_drvdata(pdev, NULL);
 228         spi_master_put(sp->bitbang.master);
 229
 230         return ret;
 231 }
 232
 233 static int ar71xx_spi_remove(struct platform_device *pdev)
 234 {
 235         struct ar71xx_spi *sp = platform_get_drvdata(pdev);
 236
 237         spi_bitbang_stop(&sp->bitbang);
 238         ar71xx_spi_restore_regs(sp);
 239         iounmap(sp->base);
 240         platform_set_drvdata(pdev, NULL);
 241         spi_master_put(sp->bitbang.master);
 242
 243         return 0;
 244 }
 245
 246 static void ar71xx_spi_shutdown(struct platform_device *pdev)
 247 {
 248         int ret;
 249
 250         ret = ar71xx_spi_remove(pdev);
 251         if (ret)
 252                 dev_err(&pdev->dev, "shutdown failed with %d\n", ret);
 253 }
 254
 255 static struct platform_driver ar71xx_spi_drv = {
 256         .probe          = ar71xx_spi_probe,
 257         .remove         = ar71xx_spi_remove,
 258         .shutdown       = ar71xx_spi_shutdown,
 259         .driver         = {
 260                 .name   = DRV_NAME,
 261                 .owner  = THIS_MODULE,
 262         },
 263 };
 264
 265 static int __init ar71xx_spi_init(void)
 266 {
 267         printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");
 268         return platform_driver_register(&ar71xx_spi_drv);
 269 }
 270 module_init(ar71xx_spi_init);
 271
 272 static void __exit ar71xx_spi_exit(void)
 273 {
 274         platform_driver_unregister(&ar71xx_spi_drv);
 275 }
 276 module_exit(ar71xx_spi_exit);
 277
 278 MODULE_ALIAS("platform:" DRV_NAME);
 279 MODULE_DESCRIPTION(DRV_DESC);
 280 MODULE_VERSION(DRV_VERSION);
 281 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 282 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org>");
 283 MODULE_LICENSE("GPL v2");