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"); 277