drivers/spi/spi-xcomm.c

   1 /*
   2  * Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver
   3  *
   4  * Copyright 2012 Analog Devices Inc.
   5  * Author: Lars-Peter Clausen <lars@metafoo.de>
   6  *
   7  * Licensed under the GPL-2 or later.
   8  */
   9
  10 #include <linux/kernel.h>
  11 #include <linux/module.h>
  12 #include <linux/delay.h>
  13 #include <linux/i2c.h>
  14 #include <linux/spi/spi.h>
  15 #include <asm/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
  31 #define SPI_XCOMM_CLOCK 48000000
  32
  33 struct spi_xcomm {
  34         struct i2c_client *i2c;
  35
  36         uint16_t settings;
  37         uint16_t chipselect;
  38
  39         unsigned int current_speed;
  40
  41         uint8_t buf[63];
  42 };
  43
  44 static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
  45 {
  46         uint16_t settings;
  47         uint8_t *buf = spi_xcomm->buf;
  48
  49         settings = spi_xcomm->settings;
  50         settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;
  51
  52         buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
  53         put_unaligned_be16(settings, &buf[1]);
  54         put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);
  55
  56         return i2c_master_send(spi_xcomm->i2c, buf, 5);
  57 }
  58
  59 static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
  60         struct spi_device *spi, int is_active)
  61 {
  62         unsigned long cs = spi->chip_select;
  63         uint16_t chipselect = spi_xcomm->chipselect;
  64
  65         if (is_active)
  66                 chipselect |= BIT(cs);
  67         else
  68                 chipselect &= ~BIT(cs);
  69
  70         spi_xcomm->chipselect = chipselect;
  71 }
  72
  73 static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
  74         struct spi_device *spi, struct spi_transfer *t, unsigned int *settings)
  75 {
  76         if (t->len > 62)
  77                 return -EINVAL;
  78
  79         if (t->speed_hz != spi_xcomm->current_speed) {
  80                 unsigned int divider;
  81
  82                 divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, t->speed_hz);
  83                 if (divider >= 64)
  84                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
  85                 else if (divider >= 16)
  86                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
  87                 else
  88                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
  89
  90                 spi_xcomm->current_speed = t->speed_hz;
  91         }
  92
  93         if (spi->mode & SPI_CPOL)
  94                 *settings |= SPI_XCOMM_SETTINGS_CPOL;
  95         else
  96                 *settings &= ~SPI_XCOMM_SETTINGS_CPOL;
  97
  98         if (spi->mode & SPI_CPHA)
  99                 *settings &= ~SPI_XCOMM_SETTINGS_CPHA;
 100         else
 101                 *settings |= SPI_XCOMM_SETTINGS_CPHA;
 102
 103         if (spi->mode & SPI_3WIRE)
 104                 *settings |= SPI_XCOMM_SETTINGS_3WIRE;
 105         else
 106                 *settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
 107
 108         return 0;
 109 }
 110
 111 static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
 112         struct spi_device *spi, struct spi_transfer *t)
 113 {
 114         int ret;
 115
 116         if (t->tx_buf) {
 117                 spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
 118                 memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
 119
 120                 ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
 121                 if (ret < 0)
 122                         return ret;
 123                 else if (ret != t->len + 1)
 124                         return -EIO;
 125         } else if (t->rx_buf) {
 126                 ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
 127                 if (ret < 0)
 128                         return ret;
 129                 else if (ret != t->len)
 130                         return -EIO;
 131         }
 132
 133         return t->len;
 134 }
 135
 136 static int spi_xcomm_transfer_one(struct spi_master *master,
 137         struct spi_message *msg)
 138 {
 139         struct spi_xcomm *spi_xcomm = spi_master_get_devdata(master);
 140         unsigned int settings = spi_xcomm->settings;
 141         struct spi_device *spi = msg->spi;
 142         unsigned cs_change = 0;
 143         struct spi_transfer *t;
 144         bool is_first = true;
 145         int status = 0;
 146         bool is_last;
 147
 148         spi_xcomm_chipselect(spi_xcomm, spi, true);
 149
 150         list_for_each_entry(t, &msg->transfers, transfer_list) {
 151
 152                 if (!t->tx_buf && !t->rx_buf && t->len) {
 153                         status = -EINVAL;
 154                         break;
 155                 }
 156
 157                 status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
 158                 if (status < 0)
 159                         break;
 160
 161                 is_last = list_is_last(&t->transfer_list, &msg->transfers);
 162                 cs_change = t->cs_change;
 163
 164                 if (cs_change ^ is_last)
 165                         settings |= BIT(5);
 166                 else
 167                         settings &= ~BIT(5);
 168
 169                 if (t->rx_buf) {
 170                         spi_xcomm->settings = settings;
 171                         status = spi_xcomm_sync_config(spi_xcomm, t->len);
 172                         if (status < 0)
 173                                 break;
 174                 } else if (settings != spi_xcomm->settings || is_first) {
 175                         spi_xcomm->settings = settings;
 176                         status = spi_xcomm_sync_config(spi_xcomm, 0);
 177                         if (status < 0)
 178                                 break;
 179                 }
 180
 181                 if (t->len) {
 182                         status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
 183
 184                         if (status < 0)
 185                                 break;
 186
 187                         if (status > 0)
 188                                 msg->actual_length += status;
 189                 }
 190                 status = 0;
 191
 192                 if (t->delay_usecs)
 193                         udelay(t->delay_usecs);
 194
 195                 is_first = false;
 196         }
 197
 198         if (status != 0 || !cs_change)
 199                 spi_xcomm_chipselect(spi_xcomm, spi, false);
 200
 201         msg->status = status;
 202         spi_finalize_current_message(master);
 203
 204         return status;
 205 }
 206
 207 static int spi_xcomm_probe(struct i2c_client *i2c,
 208         const struct i2c_device_id *id)
 209 {
 210         struct spi_xcomm *spi_xcomm;
 211         struct spi_master *master;
 212         int ret;
 213
 214         master = spi_alloc_master(&i2c->dev, sizeof(*spi_xcomm));
 215         if (!master)
 216                 return -ENOMEM;
 217
 218         spi_xcomm = spi_master_get_devdata(master);
 219         spi_xcomm->i2c = i2c;
 220
 221         master->num_chipselect = 16;
 222         master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
 223         master->bits_per_word_mask = SPI_BPW_MASK(8);
 224         master->flags = SPI_MASTER_HALF_DUPLEX;
 225         master->transfer_one_message = spi_xcomm_transfer_one;
 226         master->dev.of_node = i2c->dev.of_node;
 227         i2c_set_clientdata(i2c, master);
 228
 229         ret = devm_spi_register_master(&i2c->dev, master);
 230         if (ret < 0)
 231                 spi_master_put(master);
 232
 233         return ret;
 234 }
 235
 236 static const struct i2c_device_id spi_xcomm_ids[] = {
 237         { "spi-xcomm" },
 238         { },
 239 };
 240 MODULE_DEVICE_TABLE(i2c, spi_xcomm_ids);
 241
 242 static struct i2c_driver spi_xcomm_driver = {
 243         .driver = {
 244                 .name   = "spi-xcomm",
 245         },
 246         .id_table       = spi_xcomm_ids,
 247         .probe          = spi_xcomm_probe,
 248 };
 249 module_i2c_driver(spi_xcomm_driver);
 250
 251 MODULE_LICENSE("GPL");
 252 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 253 MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");