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

   1 /*
   2  * Atheros AR71xx SPI Controller driver
   3  *
   4  * Copyright (C) 2008 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     "0.2.2"
  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
  84                 __raw_writel(ioc_base, base + SPI_REG_IOC);
  85                 __raw_writel(sp->reg_ctrl, base + SPI_REG_CTRL);
  86                 __raw_writel(0, base + SPI_REG_FS);
  87                 break;
  88
  89         case BITBANG_CS_ACTIVE:
  90                 ioc_base = sp->get_ioc_base(spi->chip_select,
  91                                         (spi->mode & SPI_CS_HIGH) != 0,
  92                                         AR71XX_SPI_CS_ACTIVE);
  93
  94                 __raw_writel(SPI_FS_GPIO, base + SPI_REG_FS);
  95                 /* TODO: setup speed */
  96                 __raw_writel(0x43, base + SPI_REG_CTRL);
  97                 __raw_writel(ioc_base, base + SPI_REG_IOC);
  98                 sp->ioc_base = ioc_base;
  99                 break;
 100         }
 101 }
 102
 103 static u32 ar71xx_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
 104                                         u32 word, u8 bits)
 105 {
 106         struct ar71xx_spi *sp = spidev_to_sp(spi);
 107         void __iomem *base = sp->base;
 108         u32 ioc = sp->ioc_base;
 109         u32 ret;
 110
 111         /* clock starts at inactive polarity */
 112         for (word <<= (32 - bits); likely(bits); bits--) {
 113                 u32 out;
 114
 115                 if (word & (1 << 31))
 116                         out = ioc | SPI_IOC_DO;
 117                 else
 118                         out = ioc & ~SPI_IOC_DO;
 119
 120                 /* setup MSB (to slave) on trailing edge */
 121                 __raw_writel(out, base + SPI_REG_IOC);
 122
 123                 __raw_writel(out | SPI_IOC_CLK, base + SPI_REG_IOC);
 124
 125                 word <<= 1;
 126
 127 #ifdef PER_BIT_READ
 128                 /* sample MSB (from slave) on leading edge */
 129                 ret = __raw_readl(base + SPI_REG_RDS);
 130                 __raw_writel(out, base + SPI_REG_IOC);
 131 #endif
 132
 133         }
 134
 135 #ifndef PER_BIT_READ
 136         ret = __raw_readl(base + SPI_REG_RDS);
 137 #endif
 138         return ret;
 139 }
 140
 141 static int ar71xx_spi_probe(struct platform_device *pdev)
 142 {
 143         struct spi_master *master;
 144         struct ar71xx_spi *sp;
 145         struct ar71xx_spi_platform_data *pdata;
 146         struct resource *r;
 147         int ret;
 148
 149         master = spi_alloc_master(&pdev->dev, sizeof(*sp));
 150         if (master == NULL) {
 151                 dev_err(&pdev->dev, "failed to allocate spi master\n");
 152                 return -ENOMEM;
 153         }
 154
 155         sp = spi_master_get_devdata(master);
 156         platform_set_drvdata(pdev, sp);
 157
 158         pdata = pdev->dev.platform_data;
 159
 160         sp->bitbang.master = spi_master_get(master);
 161         sp->bitbang.chipselect = ar71xx_spi_chipselect;
 162         sp->bitbang.txrx_word[SPI_MODE_0] = ar71xx_spi_txrx_mode0;
 163
 164         sp->get_ioc_base = ar71xx_spi_get_ioc_base;
 165         if (pdata) {
 166                 sp->bitbang.master->bus_num = pdata->bus_num;
 167                 sp->bitbang.master->num_chipselect = pdata->num_chipselect;
 168                 if (pdata->get_ioc_base)
 169                         sp->get_ioc_base = pdata->get_ioc_base;
 170         } else {
 171                 sp->bitbang.master->bus_num = 0;
 172                 sp->bitbang.master->num_chipselect = 3;
 173         }
 174
 175         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 176         if (r == NULL) {
 177                 ret = -ENOENT;
 178                 goto err1;
 179         }
 180
 181         sp->base = ioremap_nocache(r->start, r->end - r->start + 1);
 182         if (!sp->base) {
 183                 ret = -ENXIO;
 184                 goto err1;
 185         }
 186
 187         sp->reg_ctrl = ar71xx_spi_rr(sp, SPI_REG_IOC);
 188
 189         ret = spi_bitbang_start(&sp->bitbang);
 190         if (!ret)
 191                 return 0;
 192
 193         iounmap(sp->base);
 194 err1:
 195         platform_set_drvdata(pdev, NULL);
 196         spi_master_put(sp->bitbang.master);
 197
 198         return ret;
 199 }
 200
 201 static int ar71xx_spi_remove(struct platform_device *pdev)
 202 {
 203         struct ar71xx_spi *sp = platform_get_drvdata(pdev);
 204
 205         spi_bitbang_stop(&sp->bitbang);
 206         iounmap(sp->base);
 207         platform_set_drvdata(pdev, NULL);
 208         spi_master_put(sp->bitbang.master);
 209
 210         return 0;
 211 }
 212
 213 static struct platform_driver ar71xx_spi_drv = {
 214         .probe          = ar71xx_spi_probe,
 215         .remove         = ar71xx_spi_remove,
 216         .driver         = {
 217                 .name   = DRV_NAME,
 218                 .owner  = THIS_MODULE,
 219         },
 220 };
 221
 222 static int __init ar71xx_spi_init(void)
 223 {
 224         printk(KERN_INFO DRV_DESC " version " DRV_VERSION "\n");
 225         return platform_driver_register(&ar71xx_spi_drv);
 226 }
 227 module_init(ar71xx_spi_init);
 228
 229 static void __exit ar71xx_spi_exit(void)
 230 {
 231         platform_driver_unregister(&ar71xx_spi_drv);
 232 }
 233 module_exit(ar71xx_spi_exit);
 234
 235 MODULE_ALIAS("platform:" DRV_NAME);
 236 MODULE_DESCRIPTION(DRV_DESC);
 237 MODULE_VERSION(DRV_VERSION);
 238 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 239 MODULE_AUTHOR("Imre Kaloz <kaloz@openwrt.org>");
 240 MODULE_LICENSE("GPL v2");