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