drivers/spi/spi-sc18is602.c

   1 /*
   2  * NXP SC18IS602/603 SPI driver
   3  *
   4  * Copyright (C) Guenter Roeck <linux@roeck-us.net>
   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 as published by
   8  * the Free Software Foundation; either version 2 of the License, or
   9  * (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/err.h>
  23 #include <linux/module.h>
  24 #include <linux/spi/spi.h>
  25 #include <linux/i2c.h>
  26 #include <linux/delay.h>
  27 #include <linux/pm_runtime.h>
  28 #include <linux/of.h>
  29 #include <linux/platform_data/sc18is602.h>
  30
  31 enum chips { sc18is602, sc18is602b, sc18is603 };
  32
  33 #define SC18IS602_BUFSIZ                200
  34 #define SC18IS602_CLOCK                 7372000
  35
  36 #define SC18IS602_MODE_CPHA             BIT(2)
  37 #define SC18IS602_MODE_CPOL             BIT(3)
  38 #define SC18IS602_MODE_LSB_FIRST        BIT(5)
  39 #define SC18IS602_MODE_CLOCK_DIV_4      0x0
  40 #define SC18IS602_MODE_CLOCK_DIV_16     0x1
  41 #define SC18IS602_MODE_CLOCK_DIV_64     0x2
  42 #define SC18IS602_MODE_CLOCK_DIV_128    0x3
  43
  44 struct sc18is602 {
  45         struct spi_master       *master;
  46         struct device           *dev;
  47         u8                      ctrl;
  48         u32                     freq;
  49         u32                     speed;
  50
  51         /* I2C data */
  52         struct i2c_client       *client;
  53         enum chips              id;
  54         u8                      buffer[SC18IS602_BUFSIZ + 1];
  55         int                     tlen;   /* Data queued for tx in buffer */
  56         int                     rindex; /* Receive data index in buffer */
  57 };
  58
  59 static int sc18is602_wait_ready(struct sc18is602 *hw, int len)
  60 {
  61         int i, err;
  62         int usecs = 1000000 * len / hw->speed + 1;
  63         u8 dummy[1];
  64
  65         for (i = 0; i < 10; i++) {
  66                 err = i2c_master_recv(hw->client, dummy, 1);
  67                 if (err >= 0)
  68                         return 0;
  69                 usleep_range(usecs, usecs * 2);
  70         }
  71         return -ETIMEDOUT;
  72 }
  73
  74 static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg,
  75                           struct spi_transfer *t, bool do_transfer)
  76 {
  77         unsigned int len = t->len;
  78         int ret;
  79
  80         if (hw->tlen == 0) {
  81                 /* First byte (I2C command) is chip select */
  82                 hw->buffer[0] = 1 << msg->spi->chip_select;
  83                 hw->tlen = 1;
  84                 hw->rindex = 0;
  85         }
  86         /*
  87          * We can not immediately send data to the chip, since each I2C message
  88          * resembles a full SPI message (from CS active to CS inactive).
  89          * Enqueue messages up to the first read or until do_transfer is true.
  90          */
  91         if (t->tx_buf) {
  92                 memcpy(&hw->buffer[hw->tlen], t->tx_buf, len);
  93                 hw->tlen += len;
  94                 if (t->rx_buf)
  95                         do_transfer = true;
  96                 else
  97                         hw->rindex = hw->tlen - 1;
  98         } else if (t->rx_buf) {
  99                 /*
 100                  * For receive-only transfers we still need to perform a dummy
 101                  * write to receive data from the SPI chip.
 102                  * Read data starts at the end of transmit data (minus 1 to
 103                  * account for CS).
 104                  */
 105                 hw->rindex = hw->tlen - 1;
 106                 memset(&hw->buffer[hw->tlen], 0, len);
 107                 hw->tlen += len;
 108                 do_transfer = true;
 109         }
 110
 111         if (do_transfer && hw->tlen > 1) {
 112                 ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ);
 113                 if (ret < 0)
 114                         return ret;
 115                 ret = i2c_master_send(hw->client, hw->buffer, hw->tlen);
 116                 if (ret < 0)
 117                         return ret;
 118                 if (ret != hw->tlen)
 119                         return -EIO;
 120
 121                 if (t->rx_buf) {
 122                         int rlen = hw->rindex + len;
 123
 124                         ret = sc18is602_wait_ready(hw, hw->tlen);
 125                         if (ret < 0)
 126                                 return ret;
 127                         ret = i2c_master_recv(hw->client, hw->buffer, rlen);
 128                         if (ret < 0)
 129                                 return ret;
 130                         if (ret != rlen)
 131                                 return -EIO;
 132                         memcpy(t->rx_buf, &hw->buffer[hw->rindex], len);
 133                 }
 134                 hw->tlen = 0;
 135         }
 136         return len;
 137 }
 138
 139 static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode)
 140 {
 141         u8 ctrl = 0;
 142         int ret;
 143
 144         if (mode & SPI_CPHA)
 145                 ctrl |= SC18IS602_MODE_CPHA;
 146         if (mode & SPI_CPOL)
 147                 ctrl |= SC18IS602_MODE_CPOL;
 148         if (mode & SPI_LSB_FIRST)
 149                 ctrl |= SC18IS602_MODE_LSB_FIRST;
 150
 151         /* Find the closest clock speed */
 152         if (hz >= hw->freq / 4) {
 153                 ctrl |= SC18IS602_MODE_CLOCK_DIV_4;
 154                 hw->speed = hw->freq / 4;
 155         } else if (hz >= hw->freq / 16) {
 156                 ctrl |= SC18IS602_MODE_CLOCK_DIV_16;
 157                 hw->speed = hw->freq / 16;
 158         } else if (hz >= hw->freq / 64) {
 159                 ctrl |= SC18IS602_MODE_CLOCK_DIV_64;
 160                 hw->speed = hw->freq / 64;
 161         } else {
 162                 ctrl |= SC18IS602_MODE_CLOCK_DIV_128;
 163                 hw->speed = hw->freq / 128;
 164         }
 165
 166         /*
 167          * Don't do anything if the control value did not change. The initial
 168          * value of 0xff for hw->ctrl ensures that the correct mode will be set
 169          * with the first call to this function.
 170          */
 171         if (ctrl == hw->ctrl)
 172                 return 0;
 173
 174         ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl);
 175         if (ret < 0)
 176                 return ret;
 177
 178         hw->ctrl = ctrl;
 179
 180         return 0;
 181 }
 182
 183 static int sc18is602_check_transfer(struct spi_device *spi,
 184                                     struct spi_transfer *t, int tlen)
 185 {
 186         int bpw;
 187         uint32_t hz;
 188
 189         if (t && t->len + tlen > SC18IS602_BUFSIZ)
 190                 return -EINVAL;
 191
 192         bpw = spi->bits_per_word;
 193         if (t && t->bits_per_word)
 194                 bpw = t->bits_per_word;
 195         if (bpw != 8)
 196                 return -EINVAL;
 197
 198         hz = spi->max_speed_hz;
 199         if (t && t->speed_hz)
 200                 hz = t->speed_hz;
 201         if (hz == 0)
 202                 return -EINVAL;
 203
 204         return 0;
 205 }
 206
 207 static int sc18is602_transfer_one(struct spi_master *master,
 208                                   struct spi_message *m)
 209 {
 210         struct sc18is602 *hw = spi_master_get_devdata(master);
 211         struct spi_device *spi = m->spi;
 212         struct spi_transfer *t;
 213         int status = 0;
 214
 215         /* SC18IS602 does not support CS2 */
 216         if (hw->id == sc18is602 && spi->chip_select == 2) {
 217                 status = -ENXIO;
 218                 goto error;
 219         }
 220
 221         hw->tlen = 0;
 222         list_for_each_entry(t, &m->transfers, transfer_list) {
 223                 u32 hz = t->speed_hz ? : spi->max_speed_hz;
 224                 bool do_transfer;
 225
 226                 status = sc18is602_check_transfer(spi, t, hw->tlen);
 227                 if (status < 0)
 228                         break;
 229
 230                 status = sc18is602_setup_transfer(hw, hz, spi->mode);
 231                 if (status < 0)
 232                         break;
 233
 234                 do_transfer = t->cs_change || list_is_last(&t->transfer_list,
 235                                                            &m->transfers);
 236
 237                 if (t->len) {
 238                         status = sc18is602_txrx(hw, m, t, do_transfer);
 239                         if (status < 0)
 240                                 break;
 241                         m->actual_length += status;
 242                 }
 243                 status = 0;
 244
 245                 if (t->delay_usecs)
 246                         udelay(t->delay_usecs);
 247         }
 248 error:
 249         m->status = status;
 250         spi_finalize_current_message(master);
 251
 252         return status;
 253 }
 254
 255 static int sc18is602_setup(struct spi_device *spi)
 256 {
 257         if (!spi->bits_per_word)
 258                 spi->bits_per_word = 8;
 259
 260         if (spi->mode & ~(SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST))
 261                 return -EINVAL;
 262
 263         return sc18is602_check_transfer(spi, NULL, 0);
 264 }
 265
 266 static int sc18is602_probe(struct i2c_client *client,
 267                            const struct i2c_device_id *id)
 268 {
 269         struct device *dev = &client->dev;
 270         struct device_node *np = dev->of_node;
 271         struct sc18is602_platform_data *pdata = dev_get_platdata(dev);
 272         struct sc18is602 *hw;
 273         struct spi_master *master;
 274         int error;
 275
 276         if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
 277                                      I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
 278                 return -EINVAL;
 279
 280         master = spi_alloc_master(dev, sizeof(struct sc18is602));
 281         if (!master)
 282                 return -ENOMEM;
 283
 284         hw = spi_master_get_devdata(master);
 285         i2c_set_clientdata(client, hw);
 286
 287         hw->master = master;
 288         hw->client = client;
 289         hw->dev = dev;
 290         hw->ctrl = 0xff;
 291
 292         hw->id = id->driver_data;
 293
 294         switch (hw->id) {
 295         case sc18is602:
 296         case sc18is602b:
 297                 master->num_chipselect = 4;
 298                 hw->freq = SC18IS602_CLOCK;
 299                 break;
 300         case sc18is603:
 301                 master->num_chipselect = 2;
 302                 if (pdata) {
 303                         hw->freq = pdata->clock_frequency;
 304                 } else {
 305                         const __be32 *val;
 306                         int len;
 307
 308                         val = of_get_property(np, "clock-frequency", &len);
 309                         if (val && len >= sizeof(__be32))
 310                                 hw->freq = be32_to_cpup(val);
 311                 }
 312                 if (!hw->freq)
 313                         hw->freq = SC18IS602_CLOCK;
 314                 break;
 315         }
 316         master->bus_num = client->adapter->nr;
 317         master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;
 318         master->setup = sc18is602_setup;
 319         master->transfer_one_message = sc18is602_transfer_one;
 320         master->dev.of_node = np;
 321
 322         error = spi_register_master(master);
 323         if (error)
 324                 goto error_reg;
 325
 326         return 0;
 327
 328 error_reg:
 329         spi_master_put(master);
 330         return error;
 331 }
 332
 333 static int sc18is602_remove(struct i2c_client *client)
 334 {
 335         struct sc18is602 *hw = i2c_get_clientdata(client);
 336         struct spi_master *master = hw->master;
 337
 338         spi_unregister_master(master);
 339
 340         return 0;
 341 }
 342
 343 static const struct i2c_device_id sc18is602_id[] = {
 344         { "sc18is602", sc18is602 },
 345         { "sc18is602b", sc18is602b },
 346         { "sc18is603", sc18is603 },
 347         { }
 348 };
 349 MODULE_DEVICE_TABLE(i2c, sc18is602_id);
 350
 351 static struct i2c_driver sc18is602_driver = {
 352         .driver = {
 353                 .name = "sc18is602",
 354         },
 355         .probe = sc18is602_probe,
 356         .remove = sc18is602_remove,
 357         .id_table = sc18is602_id,
 358 };
 359
 360 module_i2c_driver(sc18is602_driver);
 361
 362 MODULE_DESCRIPTION("SC18IC602/603 SPI Master Driver");
 363 MODULE_AUTHOR("Guenter Roeck");
 364 MODULE_LICENSE("GPL");