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/init.h>
  12 #include <linux/module.h>
  13 #include <linux/delay.h>
  14 #include <linux/i2c.h>
  15 #include <linux/spi/spi.h>
  16 #include <asm/unaligned.h>
  17
  18 #define SPI_XCOMM_SETTINGS_LEN_OFFSET           10
  19 #define SPI_XCOMM_SETTINGS_3WIRE                BIT(6)
  20 #define SPI_XCOMM_SETTINGS_CS_HIGH              BIT(5)
  21 #define SPI_XCOMM_SETTINGS_SAMPLE_END           BIT(4)
  22 #define SPI_XCOMM_SETTINGS_CPHA                 BIT(3)
  23 #define SPI_XCOMM_SETTINGS_CPOL                 BIT(2)
  24 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_MASK       0x3
  25 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_64         0x2
  26 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_16         0x1
  27 #define SPI_XCOMM_SETTINGS_CLOCK_DIV_4          0x0
  28
  29 #define SPI_XCOMM_CMD_UPDATE_CONFIG     0x03
  30 #define SPI_XCOMM_CMD_WRITE             0x04
  31
  32 #define SPI_XCOMM_CLOCK 48000000
  33
  34 struct spi_xcomm {
  35         struct i2c_client *i2c;
  36
  37         uint16_t settings;
  38         uint16_t chipselect;
  39
  40         unsigned int current_speed;
  41
  42         uint8_t buf[63];
  43 };
  44
  45 static int spi_xcomm_sync_config(struct spi_xcomm *spi_xcomm, unsigned int len)
  46 {
  47         uint16_t settings;
  48         uint8_t *buf = spi_xcomm->buf;
  49
  50         settings = spi_xcomm->settings;
  51         settings |= len << SPI_XCOMM_SETTINGS_LEN_OFFSET;
  52
  53         buf[0] = SPI_XCOMM_CMD_UPDATE_CONFIG;
  54         put_unaligned_be16(settings, &buf[1]);
  55         put_unaligned_be16(spi_xcomm->chipselect, &buf[3]);
  56
  57         return i2c_master_send(spi_xcomm->i2c, buf, 5);
  58 }
  59
  60 static void spi_xcomm_chipselect(struct spi_xcomm *spi_xcomm,
  61         struct spi_device *spi, int is_active)
  62 {
  63         unsigned long cs = spi->chip_select;
  64         uint16_t chipselect = spi_xcomm->chipselect;
  65
  66         if (is_active)
  67                 chipselect |= BIT(cs);
  68         else
  69                 chipselect &= ~BIT(cs);
  70
  71         spi_xcomm->chipselect = chipselect;
  72 }
  73
  74 static int spi_xcomm_setup_transfer(struct spi_xcomm *spi_xcomm,
  75         struct spi_device *spi, struct spi_transfer *t, unsigned int *settings)
  76 {
  77         unsigned int speed;
  78
  79         if ((t->bits_per_word && t->bits_per_word != 8) || t->len > 62)
  80                 return -EINVAL;
  81
  82         speed = t->speed_hz ? t->speed_hz : spi->max_speed_hz;
  83
  84         if (speed != spi_xcomm->current_speed) {
  85                 unsigned int divider = DIV_ROUND_UP(SPI_XCOMM_CLOCK, speed);
  86                 if (divider >= 64)
  87                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_64;
  88                 else if (divider >= 16)
  89                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_16;
  90                 else
  91                         *settings |= SPI_XCOMM_SETTINGS_CLOCK_DIV_4;
  92
  93                 spi_xcomm->current_speed = speed;
  94         }
  95
  96         if (spi->mode & SPI_CPOL)
  97                 *settings |= SPI_XCOMM_SETTINGS_CPOL;
  98         else
  99                 *settings &= ~SPI_XCOMM_SETTINGS_CPOL;
 100
 101         if (spi->mode & SPI_CPHA)
 102                 *settings &= ~SPI_XCOMM_SETTINGS_CPHA;
 103         else
 104                 *settings |= SPI_XCOMM_SETTINGS_CPHA;
 105
 106         if (spi->mode & SPI_3WIRE)
 107                 *settings |= SPI_XCOMM_SETTINGS_3WIRE;
 108         else
 109                 *settings &= ~SPI_XCOMM_SETTINGS_3WIRE;
 110
 111         return 0;
 112 }
 113
 114 static int spi_xcomm_txrx_bufs(struct spi_xcomm *spi_xcomm,
 115         struct spi_device *spi, struct spi_transfer *t)
 116 {
 117         int ret;
 118
 119         if (t->tx_buf) {
 120                 spi_xcomm->buf[0] = SPI_XCOMM_CMD_WRITE;
 121                 memcpy(spi_xcomm->buf + 1, t->tx_buf, t->len);
 122
 123                 ret = i2c_master_send(spi_xcomm->i2c, spi_xcomm->buf, t->len + 1);
 124                 if (ret < 0)
 125                         return ret;
 126                 else if (ret != t->len + 1)
 127                         return -EIO;
 128         } else if (t->rx_buf) {
 129                 ret = i2c_master_recv(spi_xcomm->i2c, t->rx_buf, t->len);
 130                 if (ret < 0)
 131                         return ret;
 132                 else if (ret != t->len)
 133                         return -EIO;
 134         }
 135
 136         return t->len;
 137 }
 138
 139 static int spi_xcomm_transfer_one(struct spi_master *master,
 140         struct spi_message *msg)
 141 {
 142         struct spi_xcomm *spi_xcomm = spi_master_get_devdata(master);
 143         unsigned int settings = spi_xcomm->settings;
 144         struct spi_device *spi = msg->spi;
 145         unsigned cs_change = 0;
 146         struct spi_transfer *t;
 147         bool is_first = true;
 148         int status = 0;
 149         bool is_last;
 150
 151         is_first = true;
 152
 153         spi_xcomm_chipselect(spi_xcomm, spi, true);
 154
 155         list_for_each_entry(t, &msg->transfers, transfer_list) {
 156
 157                 if (!t->tx_buf && !t->rx_buf && t->len) {
 158                         status = -EINVAL;
 159                         break;
 160                 }
 161
 162                 status = spi_xcomm_setup_transfer(spi_xcomm, spi, t, &settings);
 163                 if (status < 0)
 164                         break;
 165
 166                 is_last = list_is_last(&t->transfer_list, &msg->transfers);
 167                 cs_change = t->cs_change;
 168
 169                 if (cs_change ^ is_last)
 170                         settings |= BIT(5);
 171                 else
 172                         settings &= ~BIT(5);
 173
 174                 if (t->rx_buf) {
 175                         spi_xcomm->settings = settings;
 176                         status = spi_xcomm_sync_config(spi_xcomm, t->len);
 177                         if (status < 0)
 178                                 break;
 179                 } else if (settings != spi_xcomm->settings || is_first) {
 180                         spi_xcomm->settings = settings;
 181                         status = spi_xcomm_sync_config(spi_xcomm, 0);
 182                         if (status < 0)
 183                                 break;
 184                 }
 185
 186                 if (t->len) {
 187                         status = spi_xcomm_txrx_bufs(spi_xcomm, spi, t);
 188
 189                         if (status < 0)
 190                                 break;
 191
 192                         if (status > 0)
 193                                 msg->actual_length += status;
 194                 }
 195                 status = 0;
 196
 197                 if (t->delay_usecs)
 198                         udelay(t->delay_usecs);
 199
 200                 is_first = false;
 201         }
 202
 203         if (status != 0 || !cs_change)
 204                 spi_xcomm_chipselect(spi_xcomm, spi, false);
 205
 206         msg->status = status;
 207         spi_finalize_current_message(master);
 208
 209         return status;
 210 }
 211
 212 static int spi_xcomm_setup(struct spi_device *spi)
 213 {
 214         if (spi->bits_per_word != 8)
 215                 return -EINVAL;
 216
 217         return 0;
 218 }
 219
 220 static int spi_xcomm_probe(struct i2c_client *i2c,
 221         const struct i2c_device_id *id)
 222 {
 223         struct spi_xcomm *spi_xcomm;
 224         struct spi_master *master;
 225         int ret;
 226
 227         master = spi_alloc_master(&i2c->dev, sizeof(*spi_xcomm));
 228         if (!master)
 229                 return -ENOMEM;
 230
 231         spi_xcomm = spi_master_get_devdata(master);
 232         spi_xcomm->i2c = i2c;
 233
 234         master->num_chipselect = 16;
 235         master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_3WIRE;
 236         master->flags = SPI_MASTER_HALF_DUPLEX;
 237         master->setup = spi_xcomm_setup;
 238         master->transfer_one_message = spi_xcomm_transfer_one;
 239         master->dev.of_node = i2c->dev.of_node;
 240         i2c_set_clientdata(i2c, master);
 241
 242         ret = spi_register_master(master);
 243         if (ret < 0)
 244                 spi_master_put(master);
 245
 246         return ret;
 247 }
 248
 249 static int spi_xcomm_remove(struct i2c_client *i2c)
 250 {
 251         struct spi_master *master = i2c_get_clientdata(i2c);
 252
 253         spi_unregister_master(master);
 254
 255         return 0;
 256 }
 257
 258 static const struct i2c_device_id spi_xcomm_ids[] = {
 259         { "spi-xcomm" },
 260         { },
 261 };
 262
 263 static struct i2c_driver spi_xcomm_driver = {
 264         .driver = {
 265                 .name   = "spi-xcomm",
 266                 .owner  = THIS_MODULE,
 267         },
 268         .id_table       = spi_xcomm_ids,
 269         .probe          = spi_xcomm_probe,
 270         .remove         = spi_xcomm_remove,
 271 };
 272 module_i2c_driver(spi_xcomm_driver);
 273
 274 MODULE_LICENSE("GPL");
 275 MODULE_AUTHOR("Lars-Peter Clausen <lars@metafoo.de>");
 276 MODULE_DESCRIPTION("Analog Devices AD-FMCOMMS1-EBZ board I2C-SPI bridge driver");