target/linux/ar71xx/files/drivers/spi/pb44_spi.c

   1 /*
   2  * Atheros PB44 board SPI controller driver
   3  *
   4  * Copyright (C) 2009 Gabor Juhos <juhosg@openwrt.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/init.h>
  14 #include <linux/delay.h>
  15 #include <linux/spinlock.h>
  16 #include <linux/workqueue.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/io.h>
  19 #include <linux/spi/spi.h>
  20 #include <linux/spi/spi_bitbang.h>
  21 #include <linux/bitops.h>
  22 #include <linux/gpio.h>
  23
  24 #include <asm/mach-ar71xx/ar71xx.h>
  25 #include <asm/mach-ar71xx/platform.h>
  26
  27 #define DRV_DESC        "Atheros PB44 SPI Controller driver"
  28 #define DRV_VERSION     "0.1.0"
  29 #define DRV_NAME        "pb44-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 };
  42
  43 static inline u32 pb44_spi_rr(struct ar71xx_spi *sp, unsigned reg)
  44 {
  45         return __raw_readl(sp->base + reg);
  46 }
  47
  48 static inline void pb44_spi_wr(struct ar71xx_spi *sp, unsigned reg, u32 val)
  49 {
  50         __raw_writel(val, sp->base + reg);
  51 }
  52
  53 static inline struct ar71xx_spi *spidev_to_sp(struct spi_device *spi)
  54 {
  55         return spi_master_get_devdata(spi->master);
  56 }
  57
  58 static void pb44_spi_chipselect(struct spi_device *spi, int is_active)
  59 {
  60         struct ar71xx_spi *sp = spidev_to_sp(spi);
  61         int cs_high = (spi->mode & SPI_CS_HIGH) ? is_active : !is_active;
  62
  63         if (is_active) {
  64                 /* set initial clock polarity */
  65                 if (spi->mode & SPI_CPOL)
  66                         sp->ioc_base |= SPI_IOC_CLK;
  67                 else
  68                         sp->ioc_base &= ~SPI_IOC_CLK;
  69
  70                 pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
  71         }
  72
  73         if (spi->chip_select) {
  74                 unsigned long gpio = (unsigned long) spi->controller_data;
  75
  76                 /* SPI is normally active-low */
  77                 gpio_set_value(gpio, cs_high);
  78         } else {
  79                 if (cs_high)
  80                         sp->ioc_base |= SPI_IOC_CS0;
  81                 else
  82                         sp->ioc_base &= ~SPI_IOC_CS0;
  83
  84                 pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
  85         }
  86
  87 }
  88
  89 static int pb44_spi_setup_cs(struct spi_device *spi)
  90 {
  91         struct ar71xx_spi *sp = spidev_to_sp(spi);
  92
  93         /* enable GPIO mode */
  94         pb44_spi_wr(sp, SPI_REG_FS, SPI_FS_GPIO);
  95
  96         /* save CTRL register */
  97         sp->reg_ctrl = pb44_spi_rr(sp, SPI_REG_CTRL);
  98         sp->ioc_base = pb44_spi_rr(sp, SPI_REG_IOC);
  99
 100         /* TODO: setup speed? */
 101         pb44_spi_wr(sp, SPI_REG_CTRL, 0x43);
 102
 103         if (spi->chip_select) {
 104                 unsigned long gpio = (unsigned long) spi->controller_data;
 105                 int status = 0;
 106
 107                 status = gpio_request(gpio, dev_name(&spi->dev));
 108                 if (status)
 109                         return status;
 110
 111                 status = gpio_direction_output(gpio, spi->mode & SPI_CS_HIGH);
 112                 if (status) {
 113                         gpio_free(gpio);
 114                         return status;
 115                 }
 116         } else {
 117                 if (spi->mode & SPI_CS_HIGH)
 118                         sp->ioc_base |= SPI_IOC_CS0;
 119                 else
 120                         sp->ioc_base &= ~SPI_IOC_CS0;
 121                 pb44_spi_wr(sp, SPI_REG_IOC, sp->ioc_base);
 122         }
 123
 124         return 0;
 125 }
 126
 127 static void pb44_spi_cleanup_cs(struct spi_device *spi)
 128 {
 129         struct ar71xx_spi *sp = spidev_to_sp(spi);
 130
 131         if (spi->chip_select) {
 132                 unsigned long gpio = (unsigned long) spi->controller_data;
 133                 gpio_free(gpio);
 134         }
 135
 136         /* restore CTRL register */
 137         pb44_spi_wr(sp, SPI_REG_CTRL, sp->reg_ctrl);
 138         /* disable GPIO mode */
 139         pb44_spi_wr(sp, SPI_REG_FS, 0);
 140 }
 141
 142 static int pb44_spi_setup(struct spi_device *spi)
 143 {
 144         int status = 0;
 145
 146         if (spi->bits_per_word > 32)
 147                 return -EINVAL;
 148
 149         if (!spi->controller_state) {
 150                 status = pb44_spi_setup_cs(spi);
 151                 if (status)
 152                         return status;
 153         }
 154
 155         status = spi_bitbang_setup(spi);
 156         if (status && !spi->controller_state)
 157                 pb44_spi_cleanup_cs(spi);
 158
 159         return status;
 160 }
 161
 162 static void pb44_spi_cleanup(struct spi_device *spi)
 163 {
 164         pb44_spi_cleanup_cs(spi);
 165         spi_bitbang_cleanup(spi);
 166 }
 167
 168 static u32 pb44_spi_txrx_mode0(struct spi_device *spi, unsigned nsecs,
 169                                u32 word, u8 bits)
 170 {
 171         struct ar71xx_spi *sp = spidev_to_sp(spi);
 172         u32 ioc = sp->ioc_base;
 173         u32 ret;
 174
 175         /* clock starts at inactive polarity */
 176         for (word <<= (32 - bits); likely(bits); bits--) {
 177                 u32 out;
 178
 179                 if (word & (1 << 31))
 180                         out = ioc | SPI_IOC_DO;
 181                 else
 182                         out = ioc & ~SPI_IOC_DO;
 183
 184                 /* setup MSB (to slave) on trailing edge */
 185                 pb44_spi_wr(sp, SPI_REG_IOC, out);
 186                 pb44_spi_wr(sp, SPI_REG_IOC, out | SPI_IOC_CLK);
 187
 188                 word <<= 1;
 189
 190 #ifdef PER_BIT_READ
 191                 /* sample MSB (from slave) on leading edge */
 192                 ret = pb44_spi_rr(sp, SPI_REG_RDS);
 193                 pb44_spi_wr(sp, SPI_REG_IOC, out);
 194 #endif
 195         }
 196
 197 #ifndef PER_BIT_READ
 198         ret = pb44_spi_rr(sp, SPI_REG_RDS);
 199 #endif
 200         return ret;
 201 }
 202
 203 static int pb44_spi_probe(struct platform_device *pdev)
 204 {
 205         struct spi_master *master;
 206         struct ar71xx_spi *sp;
 207         struct ar71xx_spi_platform_data *pdata;
 208         struct resource *r;
 209         int ret;
 210
 211         master = spi_alloc_master(&pdev->dev, sizeof(*sp));
 212         if (master == NULL) {
 213                 dev_err(&pdev->dev, "failed to allocate spi master\n");
 214                 return -ENOMEM;
 215         }
 216
 217         sp = spi_master_get_devdata(master);
 218         platform_set_drvdata(pdev, sp);
 219
 220         pdata = pdev->dev.platform_data;
 221
 222         master->setup = pb44_spi_setup;
 223         master->cleanup = pb44_spi_cleanup;
 224         if (pdata) {
 225                 master->bus_num = pdata->bus_num;
 226                 master->num_chipselect = pdata->num_chipselect;
 227         } else {
 228                 master->bus_num = 0;
 229                 master->num_chipselect = 1;
 230         }
 231
 232         sp->bitbang.master = spi_master_get(master);
 233         sp->bitbang.chipselect = pb44_spi_chipselect;
 234         sp->bitbang.txrx_word[SPI_MODE_0] = pb44_spi_txrx_mode0;
 235         sp->bitbang.setup_transfer = spi_bitbang_setup_transfer;
 236         sp->bitbang.flags = SPI_CS_HIGH;
 237
 238         r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 239         if (r == NULL) {
 240                 ret = -ENOENT;
 241                 goto err1;
 242         }
 243
 244         sp->base = ioremap_nocache(r->start, r->end - r->start + 1);
 245         if (!sp->base) {
 246                 ret = -ENXIO;
 247                 goto err1;
 248         }
 249
 250         ret = spi_bitbang_start(&sp->bitbang);
 251         if (!ret)
 252                 return 0;
 253
 254         iounmap(sp->base);
 255  err1:
 256         platform_set_drvdata(pdev, NULL);
 257         spi_master_put(sp->bitbang.master);
 258
 259         return ret;
 260 }
 261
 262 static int pb44_spi_remove(struct platform_device *pdev)
 263 {
 264         struct ar71xx_spi *sp = platform_get_drvdata(pdev);
 265
 266         spi_bitbang_stop(&sp->bitbang);
 267         iounmap(sp->base);
 268         platform_set_drvdata(pdev, NULL);
 269         spi_master_put(sp->bitbang.master);
 270
 271         return 0;
 272 }
 273
 274 static struct platform_driver pb44_spi_drv = {
 275         .probe          = pb44_spi_probe,
 276         .remove         = pb44_spi_remove,
 277         .driver         = {
 278                 .name   = DRV_NAME,
 279                 .owner  = THIS_MODULE,
 280         },
 281 };
 282
 283 static int __init pb44_spi_init(void)
 284 {
 285         return platform_driver_register(&pb44_spi_drv);
 286 }
 287 module_init(pb44_spi_init);
 288
 289 static void __exit pb44_spi_exit(void)
 290 {
 291         platform_driver_unregister(&pb44_spi_drv);
 292 }
 293 module_exit(pb44_spi_exit);
 294
 295 MODULE_ALIAS("platform:" DRV_NAME);
 296 MODULE_DESCRIPTION(DRV_DESC);
 297 MODULE_VERSION(DRV_VERSION);
 298 MODULE_AUTHOR("Gabor Juhos <juhosg@openwrt.org>");
 299 MODULE_LICENSE("GPL v2");