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