drivers/spi/spi-xcomm.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver
   4  *
   5  * Copyright 2012 Analog Devices Inc.
   6  * Author: Lars-Peter Clausen <lars@metafoo.de>
   7  */
   8
   9 #include <linux/kernel.h>
  10 #include <linux/module.h>
  11 #include <linux/delay.h>
  12 #include <linux/i2c.h>
  13 #include <linux/gpio/driver.h>
  14 #include <linux/spi/spi.h>
  15 #include <linux/unaligned.h>
  16
  17 #define SPI_XCOMM_SETTINGS_LEN_OFFSET           10
  18 #define SPI_XCOMM_SETTINGS_3WIRE                BIT(6)
  19 #define SPI_XCOMM_SETTINGS_CS_HIGH              BIT(5)
  20 #define SPI_XCOMM_SETTINGS_SAMPLE_END           BIT(4)
  21 #define SPI_XCOMM_SETTINGS_CPHA                 BIT(3)
  22 #define SPI_XCOMM_SETTINGS_CPOL                 BIT(2)
  23 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_MASK       0x3
  24 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_64         0x2
  25 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_16         0x1
  26 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_4          0x0
  27
  28 #define SPI_XCOMM_CMD_UPDATE_CONFIG     0x03
  29 #define SPI_XCOMM_CMD_WRITE             0x04
  30 #define SPI_XCOMM_CMD_GPIO_SET          0x05
  31
  32 #define SPI_XCOMM_CLOCK 48000000
  33
  34 struct spi_xcomm {
  35         struct i2c_client *i2c;
  36
  37         struct gpio_chip gc;
  38
  39         u16 settings;
  40         u16 chipselect;
  41
  42         unsigned int current_speed;
  43
  44         u8 buf[63];
  45 };
  46
  47 static void spi_xcomm_gpio_set_value(struct gpio_chip *chip,
  48                                      unsigned int offset, int val)
  49 {
  50         struct spi_xcomm *spi_xcomm = gpiochip_get_data(chip);
  51         unsigned char buf[2];
  52
  53         buf[0] = SPI_XCOMM_CMD_GPIO_SET;
  54         buf[1] = !!val;
  55
  56         i2c_master_send(spi_xcomm->i2c, buf, 2);
  57 }
  58
  59 static int spi_xcomm_gpio_get_direction(struct gpio_chip *chip,
  60                                         unsigned int offset)
  61 {
  62         return GPIO_LINE_DIRECTION_OUT;
  63 }
  64
  65 static int spi_xcomm_gpio_add(struct spi_xcomm *spi_xcomm)
  66 {
  67         struct device *dev = &spi_xcomm->i2c->dev;
  68
  69         if (!IS_ENABLED(CONFIG_GPIOLIB))
  70                 return 0;
  71
  72         spi_xcomm->gc.get_direction = spi_xcomm_gpio_get_direction;
  73         spi_xcomm->gc.set = spi_xcomm_gpio_set_value;
  74         spi_xcomm->gc.can_sleep = 1;
  75         spi_xcomm->gc.base = -1;
  76         spi_xcomm->gc.ngpio = 1;
  77         spi_xcomm->gc.label = spi_xcomm->i2c->name;
  78         spi_xcomm->gc.owner = THIS_MODULE;
  79
  80         return devm_gpiochip_add_data(dev, &spi_xcomm->gc, spi_xcomm);
  81 }
  82
  83 static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
  84 {
  85         u16 settings;
  86         u8 *buf = spi_xcomm->buf;
  87
  88         settings = spi_xcomm->settings;
  89         settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;
  90
  91         buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
  92         put_unaligned_be16(settings, &buf[1]);
  93         put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);
  94
  95         return i2c_master_send(spi_xcomm->i2c, buf, 5);
  96 }
  97
  98 static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
  99                                  struct spi_device *spi, int is_active)
 100 {
 101         unsigned long cs = spi_get_chipselect(spi, 0);
 102         u16 chipselect = spi_xcomm->chipselect;
 103
 104         if (is_active)
 105                 chipselect |= BIT(cs);
 106         else
 107                 chipselect &= ~BIT(cs);
 108
 109         spi_xcomm->chipselect = chipselect;
 110 }
 111
 112 static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
 113                                     struct spi_device *spi, struct spi_transfer *t,
 114                                     unsigned int *settings)
 115 {
 116         if (t->len > 62)
 117                 return -EINVAL;
 118
 119         if (t->speed_hz != spi_xcomm->current_speed) {
 120                 unsigned int divider;
 121
 122                 divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, t->speed_hz);
 123                 if (divider >= 64)
 124                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
 125                 else if (divider >= 16)
 126                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
 127                 else
 128                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
 129
 130                 spi_xcomm->current_speed = t->speed_hz;
 131         }
 132
 133         if (spi->mode & SPI_CPOL)
 134                 *settings |= SPI_XCOMM_SETTINGS_CPOL;
 135         else
 136                 *settings &= ~SPI_XCOMM_SETTINGS_CPOL;
 137
 138         if (spi->mode & SPI_CPHA)
 139                 *settings &= ~SPI_XCOMM_SETTINGS_CPHA;
 140         else
 141                 *settings |= SPI_XCOMM_SETTINGS_CPHA;
 142
 143         if (spi->mode & SPI_3WIRE)
 144                 *settings |= SPI_XCOMM_SETTINGS_3WIRE;
 145         else
 146                 *settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
 147
 148         return 0;
 149 }
 150
 151 static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
 152                                struct spi_device *spi, struct spi_transfer *t)
 153 {
 154         int ret;
 155
 156         if (t->tx_buf) {
 157                 spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
 158                 memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
 159
 160                 ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
 161                 if (ret < 0)
 162                         return ret;
 163                 if (ret != t->len + 1)
 164                         return -EIO;
 165         } else if (t->rx_buf) {
 166                 ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
 167                 if (ret < 0)
 168                         return ret;
 169                 if (ret != t->len)
 170                         return -EIO;
 171         }
 172
 173         return t->len;
 174 }
 175
 176 static int spi_xcomm_transfer_one(struct spi_controller *host,
 177                                   struct spi_message *msg)
 178 {
 179         struct spi_xcomm *spi_xcomm = spi_controller_get_devdata(host);
 180         unsigned int settings = spi_xcomm->settings;
 181         struct spi_device *spi = msg->spi;
 182         unsigned int cs_change = 0;
 183         struct spi_transfer *t;
 184         bool is_first = true;
 185         int status = 0;
 186         bool is_last;
 187
 188         spi_xcomm_chipselect(spi_xcomm, spi, true);
 189
 190         list_for_each_entry(t, &msg->transfers, transfer_list) {
 191                 if (!t->tx_buf && !t->rx_buf && t->len) {
 192                         status = -EINVAL;
 193                         break;
 194                 }
 195
 196                 status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
 197                 if (status < 0)
 198                         break;
 199
 200                 is_last = list_is_last(&t->transfer_list, &msg->transfers);
 201                 cs_change = t->cs_change;
 202
 203                 if (cs_change ^ is_last)
 204                         settings |= BIT(5);
 205                 else
 206                         settings &= ~BIT(5);
 207
 208                 if (t->rx_buf) {
 209                         spi_xcomm->settings = settings;
 210                         status = spi_xcomm_sync_config(spi_xcomm, t->len);
 211                         if (status < 0)
 212                                 break;
 213                 } else if (settings != spi_xcomm->settings || is_first) {
 214                         spi_xcomm->settings = settings;
 215                         status = spi_xcomm_sync_config(spi_xcomm, 0);
 216                         if (status < 0)
 217                                 break;
 218                 }
 219
 220                 if (t->len) {
 221                         status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
 222
 223                         if (status < 0)
 224                                 break;
 225
 226                         if (status > 0)
 227                                 msg->actual_length += status;
 228                 }
 229                 status = 0;
 230
 231                 spi_transfer_delay_exec(t);
 232
 233                 is_first = false;
 234         }
 235
 236         if (status != 0 || !cs_change)
 237                 spi_xcomm_chipselect(spi_xcomm, spi, false);
 238
 239         msg->status = status;
 240         spi_finalize_current_message(host);
 241
 242         return status;
 243 }
 244
 245 static int spi_xcomm_probe(struct i2c_client *i2c)
 246 {
 247         struct spi_xcomm *spi_xcomm;
 248         struct spi_controller *host;
 249         int ret;
 250
 251         host = devm_spi_alloc_host(&i2c->dev, sizeof(*spi_xcomm));
 252         if (!host)
 253                 return -ENOMEM;
 254
 255         spi_xcomm = spi_controller_get_devdata(host);
 256         spi_xcomm->i2c = i2c;
 257
 258         host->num_chipselect = 16;
 259         host->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
 260         host->bits_per_word_mask = SPI_BPW_MASK(8);
 261         host->flags = SPI_CONTROLLER_HALF_DUPLEX;
 262         host->transfer_one_message = spi_xcomm_transfer_one;
 263         host->dev.of_node = i2c->dev.of_node;
 264
 265         ret = devm_spi_register_controller(&i2c->dev, host);
 266         if (ret < 0)
 267                 return ret;
 268
 269         return spi_xcomm_gpio_add(spi_xcomm);
 270 }
 271
 272 static const struct i2c_device_id spi_xcomm_ids[] = {
 273         { "spi-xcomm" },
 274         { },
 275 };
 276 MODULE_DEVICE_TABLE(i2c, spi_xcomm_ids);
 277
 278 static struct i2c_driver spi_xcomm_driver = {
 279         .driver = {
 280                 .name   = "spi-xcomm",
 281         },
 282         .id_table       = spi_xcomm_ids,
 283         .probe          = spi_xcomm_probe,
 284 };
 285 module_i2c_driver(spi_xcomm_driver);
 286
 287 MODULE_LICENSE("GPL");
 288 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 289 MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");