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