1 /* 2 * NXP SC18IS602/603 SPI driver 3 * 4 * Copyright (C) Guenter Roeck <linux@roeck-us.net> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation; either version 2 of the License, or 9 * (at your option) any later version. 10 * 11 * This program is distributed in the hope that it will be useful, 12 * but WITHOUT ANY WARRANTY; without even the implied warranty of 13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 14 * GNU General Public License for more details. 15 */ 16 17 #include <linux/kernel.h> 18 #include <linux/err.h> 19 #include <linux/module.h> 20 #include <linux/spi/spi.h> 21 #include <linux/i2c.h> 22 #include <linux/delay.h> 23 #include <linux/pm_runtime.h> 24 #include <linux/of.h> 25 #include <linux/platform_data/sc18is602.h> 26 27 enum chips { sc18is602, sc18is602b, sc18is603 }; 28 29 #define SC18IS602_BUFSIZ 200 30 #define SC18IS602_CLOCK 7372000 31 32 #define SC18IS602_MODE_CPHA BIT(2) 33 #define SC18IS602_MODE_CPOL BIT(3) 34 #define SC18IS602_MODE_LSB_FIRST BIT(5) 35 #define SC18IS602_MODE_CLOCK_DIV_4 0x0 36 #define SC18IS602_MODE_CLOCK_DIV_16 0x1 37 #define SC18IS602_MODE_CLOCK_DIV_64 0x2 38 #define SC18IS602_MODE_CLOCK_DIV_128 0x3 39 40 struct sc18is602 { 41 struct spi_master *master; 42 struct device *dev; 43 u8 ctrl; 44 u32 freq; 45 u32 speed; 46 47 /* I2C data */ 48 struct i2c_client *client; 49 enum chips id; 50 u8 buffer[SC18IS602_BUFSIZ + 1]; 51 int tlen; /* Data queued for tx in buffer */ 52 int rindex; /* Receive data index in buffer */ 53 }; 54 55 static int sc18is602_wait_ready(struct sc18is602 *hw, int len) 56 { 57 int i, err; 58 int usecs = 1000000 * len / hw->speed + 1; 59 u8 dummy[1]; 60 61 for (i = 0; i < 10; i++) { 62 err = i2c_master_recv(hw->client, dummy, 1); 63 if (err >= 0) 64 return 0; 65 usleep_range(usecs, usecs * 2); 66 } 67 return -ETIMEDOUT; 68 } 69 70 static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg, 71 struct spi_transfer *t, bool do_transfer) 72 { 73 unsigned int len = t->len; 74 int ret; 75 76 if (hw->tlen == 0) { 77 /* First byte (I2C command) is chip select */ 78 hw->buffer[0] = 1 << msg->spi->chip_select; 79 hw->tlen = 1; 80 hw->rindex = 0; 81 } 82 /* 83 * We can not immediately send data to the chip, since each I2C message 84 * resembles a full SPI message (from CS active to CS inactive). 85 * Enqueue messages up to the first read or until do_transfer is true. 86 */ 87 if (t->tx_buf) { 88 memcpy(&hw->buffer[hw->tlen], t->tx_buf, len); 89 hw->tlen += len; 90 if (t->rx_buf) 91 do_transfer = true; 92 else 93 hw->rindex = hw->tlen - 1; 94 } else if (t->rx_buf) { 95 /* 96 * For receive-only transfers we still need to perform a dummy 97 * write to receive data from the SPI chip. 98 * Read data starts at the end of transmit data (minus 1 to 99 * account for CS). 100 */ 101 hw->rindex = hw->tlen - 1; 102 memset(&hw->buffer[hw->tlen], 0, len); 103 hw->tlen += len; 104 do_transfer = true; 105 } 106 107 if (do_transfer && hw->tlen > 1) { 108 ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ); 109 if (ret < 0) 110 return ret; 111 ret = i2c_master_send(hw->client, hw->buffer, hw->tlen); 112 if (ret < 0) 113 return ret; 114 if (ret != hw->tlen) 115 return -EIO; 116 117 if (t->rx_buf) { 118 int rlen = hw->rindex + len; 119 120 ret = sc18is602_wait_ready(hw, hw->tlen); 121 if (ret < 0) 122 return ret; 123 ret = i2c_master_recv(hw->client, hw->buffer, rlen); 124 if (ret < 0) 125 return ret; 126 if (ret != rlen) 127 return -EIO; 128 memcpy(t->rx_buf, &hw->buffer[hw->rindex], len); 129 } 130 hw->tlen = 0; 131 } 132 return len; 133 } 134 135 static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode) 136 { 137 u8 ctrl = 0; 138 int ret; 139 140 if (mode & SPI_CPHA) 141 ctrl |= SC18IS602_MODE_CPHA; 142 if (mode & SPI_CPOL) 143 ctrl |= SC18IS602_MODE_CPOL; 144 if (mode & SPI_LSB_FIRST) 145 ctrl |= SC18IS602_MODE_LSB_FIRST; 146 147 /* Find the closest clock speed */ 148 if (hz >= hw->freq / 4) { 149 ctrl |= SC18IS602_MODE_CLOCK_DIV_4; 150 hw->speed = hw->freq / 4; 151 } else if (hz >= hw->freq / 16) { 152 ctrl |= SC18IS602_MODE_CLOCK_DIV_16; 153 hw->speed = hw->freq / 16; 154 } else if (hz >= hw->freq / 64) { 155 ctrl |= SC18IS602_MODE_CLOCK_DIV_64; 156 hw->speed = hw->freq / 64; 157 } else { 158 ctrl |= SC18IS602_MODE_CLOCK_DIV_128; 159 hw->speed = hw->freq / 128; 160 } 161 162 /* 163 * Don't do anything if the control value did not change. The initial 164 * value of 0xff for hw->ctrl ensures that the correct mode will be set 165 * with the first call to this function. 166 */ 167 if (ctrl == hw->ctrl) 168 return 0; 169 170 ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl); 171 if (ret < 0) 172 return ret; 173 174 hw->ctrl = ctrl; 175 176 return 0; 177 } 178 179 static int sc18is602_check_transfer(struct spi_device *spi, 180 struct spi_transfer *t, int tlen) 181 { 182 if (t && t->len + tlen > SC18IS602_BUFSIZ) 183 return -EINVAL; 184 185 return 0; 186 } 187 188 static int sc18is602_transfer_one(struct spi_master *master, 189 struct spi_message *m) 190 { 191 struct sc18is602 *hw = spi_master_get_devdata(master); 192 struct spi_device *spi = m->spi; 193 struct spi_transfer *t; 194 int status = 0; 195 196 hw->tlen = 0; 197 list_for_each_entry(t, &m->transfers, transfer_list) { 198 bool do_transfer; 199 200 status = sc18is602_check_transfer(spi, t, hw->tlen); 201 if (status < 0) 202 break; 203 204 status = sc18is602_setup_transfer(hw, t->speed_hz, spi->mode); 205 if (status < 0) 206 break; 207 208 do_transfer = t->cs_change || list_is_last(&t->transfer_list, 209 &m->transfers); 210 211 if (t->len) { 212 status = sc18is602_txrx(hw, m, t, do_transfer); 213 if (status < 0) 214 break; 215 m->actual_length += status; 216 } 217 status = 0; 218 219 if (t->delay_usecs) 220 udelay(t->delay_usecs); 221 } 222 m->status = status; 223 spi_finalize_current_message(master); 224 225 return status; 226 } 227 228 static int sc18is602_setup(struct spi_device *spi) 229 { 230 struct sc18is602 *hw = spi_master_get_devdata(spi->master); 231 232 /* SC18IS602 does not support CS2 */ 233 if (hw->id == sc18is602 && spi->chip_select == 2) 234 return -ENXIO; 235 236 return 0; 237 } 238 239 static int sc18is602_probe(struct i2c_client *client, 240 const struct i2c_device_id *id) 241 { 242 struct device *dev = &client->dev; 243 struct device_node *np = dev->of_node; 244 struct sc18is602_platform_data *pdata = dev_get_platdata(dev); 245 struct sc18is602 *hw; 246 struct spi_master *master; 247 int error; 248 249 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | 250 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) 251 return -EINVAL; 252 253 master = spi_alloc_master(dev, sizeof(struct sc18is602)); 254 if (!master) 255 return -ENOMEM; 256 257 hw = spi_master_get_devdata(master); 258 i2c_set_clientdata(client, hw); 259 260 hw->master = master; 261 hw->client = client; 262 hw->dev = dev; 263 hw->ctrl = 0xff; 264 265 hw->id = id->driver_data; 266 267 switch (hw->id) { 268 case sc18is602: 269 case sc18is602b: 270 master->num_chipselect = 4; 271 hw->freq = SC18IS602_CLOCK; 272 break; 273 case sc18is603: 274 master->num_chipselect = 2; 275 if (pdata) { 276 hw->freq = pdata->clock_frequency; 277 } else { 278 const __be32 *val; 279 int len; 280 281 val = of_get_property(np, "clock-frequency", &len); 282 if (val && len >= sizeof(__be32)) 283 hw->freq = be32_to_cpup(val); 284 } 285 if (!hw->freq) 286 hw->freq = SC18IS602_CLOCK; 287 break; 288 } 289 master->bus_num = np ? -1 : client->adapter->nr; 290 master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST; 291 master->bits_per_word_mask = SPI_BPW_MASK(8); 292 master->setup = sc18is602_setup; 293 master->transfer_one_message = sc18is602_transfer_one; 294 master->dev.of_node = np; 295 master->min_speed_hz = hw->freq / 128; 296 master->max_speed_hz = hw->freq / 4; 297 298 error = devm_spi_register_master(dev, master); 299 if (error) 300 goto error_reg; 301 302 return 0; 303 304 error_reg: 305 spi_master_put(master); 306 return error; 307 } 308 309 static const struct i2c_device_id sc18is602_id[] = { 310 { "sc18is602", sc18is602 }, 311 { "sc18is602b", sc18is602b }, 312 { "sc18is603", sc18is603 }, 313 { } 314 }; 315 MODULE_DEVICE_TABLE(i2c, sc18is602_id); 316 317 static struct i2c_driver sc18is602_driver = { 318 .driver = { 319 .name = "sc18is602", 320 }, 321 .probe = sc18is602_probe, 322 .id_table = sc18is602_id, 323 }; 324 325 module_i2c_driver(sc18is602_driver); 326 327 MODULE_DESCRIPTION("SC18IC602/603 SPI Master Driver"); 328 MODULE_AUTHOR("Guenter Roeck"); 329 MODULE_LICENSE("GPL"); 330