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