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         unsigned int speed;
  77
  78         if (t->len > 62)
  79                 return -EINVAL;
  80
  81         speed = t->speed_hz ? t->speed_hz : spi->max_speed_hz;
  82
  83         if (speed != spi_xcomm->current_speed) {
  84                 unsigned int divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, speed);
  85                 if (divider >= 64)
  86                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
  87                 else if (divider >= 16)
  88                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
  89                 else
  90                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
  91
  92                 spi_xcomm->current_speed = speed;
  93         }
  94
  95         if (spi->mode & SPI_CPOL)
  96                 *settings |= SPI_XCOMM_SETTINGS_CPOL;
  97         else
  98                 *settings &= ~SPI_XCOMM_SETTINGS_CPOL;
  99
 100         if (spi->mode & SPI_CPHA)
 101                 *settings &= ~SPI_XCOMM_SETTINGS_CPHA;
 102         else
 103                 *settings |= SPI_XCOMM_SETTINGS_CPHA;
 104
 105         if (spi->mode & SPI_3WIRE)
 106                 *settings |= SPI_XCOMM_SETTINGS_3WIRE;
 107         else
 108                 *settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
 109
 110         return 0;
 111 }
 112
 113 static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
 114         struct spi_device *spi, struct spi_transfer *t)
 115 {
 116         int ret;
 117
 118         if (t->tx_buf) {
 119                 spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
 120                 memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
 121
 122                 ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
 123                 if (ret < 0)
 124                         return ret;
 125                 else if (ret != t->len + 1)
 126                         return -EIO;
 127         } else if (t->rx_buf) {
 128                 ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
 129                 if (ret < 0)
 130                         return ret;
 131                 else if (ret != t->len)
 132                         return -EIO;
 133         }
 134
 135         return t->len;
 136 }
 137
 138 static int spi_xcomm_transfer_one(struct spi_master *master,
 139         struct spi_message *msg)
 140 {
 141         struct spi_xcomm *spi_xcomm = spi_master_get_devdata(master);
 142         unsigned int settings = spi_xcomm->settings;
 143         struct spi_device *spi = msg->spi;
 144         unsigned cs_change = 0;
 145         struct spi_transfer *t;
 146         bool is_first = true;
 147         int status = 0;
 148         bool is_last;
 149
 150         is_first = true;
 151
 152         spi_xcomm_chipselect(spi_xcomm, spi, true);
 153
 154         list_for_each_entry(t, &msg->transfers, transfer_list) {
 155
 156                 if (!t->tx_buf && !t->rx_buf && t->len) {
 157                         status = -EINVAL;
 158                         break;
 159                 }
 160
 161                 status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
 162                 if (status < 0)
 163                         break;
 164
 165                 is_last = list_is_last(&t->transfer_list, &msg->transfers);
 166                 cs_change = t->cs_change;
 167
 168                 if (cs_change ^ is_last)
 169                         settings |= BIT(5);
 170                 else
 171                         settings &= ~BIT(5);
 172
 173                 if (t->rx_buf) {
 174                         spi_xcomm->settings = settings;
 175                         status = spi_xcomm_sync_config(spi_xcomm, t->len);
 176                         if (status < 0)
 177                                 break;
 178                 } else if (settings != spi_xcomm->settings || is_first) {
 179                         spi_xcomm->settings = settings;
 180                         status = spi_xcomm_sync_config(spi_xcomm, 0);
 181                         if (status < 0)
 182                                 break;
 183                 }
 184
 185                 if (t->len) {
 186                         status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
 187
 188                         if (status < 0)
 189                                 break;
 190
 191                         if (status > 0)
 192                                 msg->actual_length += status;
 193                 }
 194                 status = 0;
 195
 196                 if (t->delay_usecs)
 197                         udelay(t->delay_usecs);
 198
 199                 is_first = false;
 200         }
 201
 202         if (status != 0 || !cs_change)
 203                 spi_xcomm_chipselect(spi_xcomm, spi, false);
 204
 205         msg->status = status;
 206         spi_finalize_current_message(master);
 207
 208         return status;
 209 }
 210
 211 static int spi_xcomm_probe(struct i2c_client *i2c,
 212         const struct i2c_device_id *id)
 213 {
 214         struct spi_xcomm *spi_xcomm;
 215         struct spi_master *master;
 216         int ret;
 217
 218         master = spi_alloc_master(&i2c->dev, sizeof(*spi_xcomm));
 219         if (!master)
 220                 return -ENOMEM;
 221
 222         spi_xcomm = spi_master_get_devdata(master);
 223         spi_xcomm->i2c = i2c;
 224
 225         master->num_chipselect = 16;
 226         master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
 227         master->bits_per_word_mask = SPI_BPW_MASK(8);
 228         master->flags = SPI_MASTER_HALF_DUPLEX;
 229         master->transfer_one_message = spi_xcomm_transfer_one;
 230         master->dev.of_node = i2c->dev.of_node;
 231         i2c_set_clientdata(i2c, master);
 232
 233         ret = devm_spi_register_master(&i2c->dev, master);
 234         if (ret < 0)
 235                 spi_master_put(master);
 236
 237         return ret;
 238 }
 239
 240 static const struct i2c_device_id spi_xcomm_ids[] = {
 241         { "spi-xcomm" },
 242         { },
 243 };
 244
 245 static struct i2c_driver spi_xcomm_driver = {
 246         .driver = {
 247                 .name   = "spi-xcomm",
 248                 .owner  = THIS_MODULE,
 249         },
 250         .id_table       = spi_xcomm_ids,
 251         .probe          = spi_xcomm_probe,
 252 };
 253 module_i2c_driver(spi_xcomm_driver);
 254
 255 MODULE_LICENSE("GPL");
 256 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 257 MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");