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