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 #include <linux/gpio/consumer.h> 27 28 enum chips { sc18is602, sc18is602b, sc18is603 }; 29 30 #define SC18IS602_BUFSIZ 200 31 #define SC18IS602_CLOCK 7372000 32 33 #define SC18IS602_MODE_CPHA BIT(2) 34 #define SC18IS602_MODE_CPOL BIT(3) 35 #define SC18IS602_MODE_LSB_FIRST BIT(5) 36 #define SC18IS602_MODE_CLOCK_DIV_4 0x0 37 #define SC18IS602_MODE_CLOCK_DIV_16 0x1 38 #define SC18IS602_MODE_CLOCK_DIV_64 0x2 39 #define SC18IS602_MODE_CLOCK_DIV_128 0x3 40 41 struct sc18is602 { 42 struct spi_master *master; 43 struct device *dev; 44 u8 ctrl; 45 u32 freq; 46 u32 speed; 47 48 /* I2C data */ 49 struct i2c_client *client; 50 enum chips id; 51 u8 buffer[SC18IS602_BUFSIZ + 1]; 52 int tlen; /* Data queued for tx in buffer */ 53 int rindex; /* Receive data index in buffer */ 54 55 struct gpio_desc *reset; 56 }; 57 58 static int sc18is602_wait_ready(struct sc18is602 *hw, int len) 59 { 60 int i, err; 61 int usecs = 1000000 * len / hw->speed + 1; 62 u8 dummy[1]; 63 64 for (i = 0; i < 10; i++) { 65 err = i2c_master_recv(hw->client, dummy, 1); 66 if (err >= 0) 67 return 0; 68 usleep_range(usecs, usecs * 2); 69 } 70 return -ETIMEDOUT; 71 } 72 73 static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg, 74 struct spi_transfer *t, bool do_transfer) 75 { 76 unsigned int len = t->len; 77 int ret; 78 79 if (hw->tlen == 0) { 80 /* First byte (I2C command) is chip select */ 81 hw->buffer[0] = 1 << msg->spi->chip_select; 82 hw->tlen = 1; 83 hw->rindex = 0; 84 } 85 /* 86 * We can not immediately send data to the chip, since each I2C message 87 * resembles a full SPI message (from CS active to CS inactive). 88 * Enqueue messages up to the first read or until do_transfer is true. 89 */ 90 if (t->tx_buf) { 91 memcpy(&hw->buffer[hw->tlen], t->tx_buf, len); 92 hw->tlen += len; 93 if (t->rx_buf) 94 do_transfer = true; 95 else 96 hw->rindex = hw->tlen - 1; 97 } else if (t->rx_buf) { 98 /* 99 * For receive-only transfers we still need to perform a dummy 100 * write to receive data from the SPI chip. 101 * Read data starts at the end of transmit data (minus 1 to 102 * account for CS). 103 */ 104 hw->rindex = hw->tlen - 1; 105 memset(&hw->buffer[hw->tlen], 0, len); 106 hw->tlen += len; 107 do_transfer = true; 108 } 109 110 if (do_transfer && hw->tlen > 1) { 111 ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ); 112 if (ret < 0) 113 return ret; 114 ret = i2c_master_send(hw->client, hw->buffer, hw->tlen); 115 if (ret < 0) 116 return ret; 117 if (ret != hw->tlen) 118 return -EIO; 119 120 if (t->rx_buf) { 121 int rlen = hw->rindex + len; 122 123 ret = sc18is602_wait_ready(hw, hw->tlen); 124 if (ret < 0) 125 return ret; 126 ret = i2c_master_recv(hw->client, hw->buffer, rlen); 127 if (ret < 0) 128 return ret; 129 if (ret != rlen) 130 return -EIO; 131 memcpy(t->rx_buf, &hw->buffer[hw->rindex], len); 132 } 133 hw->tlen = 0; 134 } 135 return len; 136 } 137 138 static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode) 139 { 140 u8 ctrl = 0; 141 int ret; 142 143 if (mode & SPI_CPHA) 144 ctrl |= SC18IS602_MODE_CPHA; 145 if (mode & SPI_CPOL) 146 ctrl |= SC18IS602_MODE_CPOL; 147 if (mode & SPI_LSB_FIRST) 148 ctrl |= SC18IS602_MODE_LSB_FIRST; 149 150 /* Find the closest clock speed */ 151 if (hz >= hw->freq / 4) { 152 ctrl |= SC18IS602_MODE_CLOCK_DIV_4; 153 hw->speed = hw->freq / 4; 154 } else if (hz >= hw->freq / 16) { 155 ctrl |= SC18IS602_MODE_CLOCK_DIV_16; 156 hw->speed = hw->freq / 16; 157 } else if (hz >= hw->freq / 64) { 158 ctrl |= SC18IS602_MODE_CLOCK_DIV_64; 159 hw->speed = hw->freq / 64; 160 } else { 161 ctrl |= SC18IS602_MODE_CLOCK_DIV_128; 162 hw->speed = hw->freq / 128; 163 } 164 165 /* 166 * Don't do anything if the control value did not change. The initial 167 * value of 0xff for hw->ctrl ensures that the correct mode will be set 168 * with the first call to this function. 169 */ 170 if (ctrl == hw->ctrl) 171 return 0; 172 173 ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl); 174 if (ret < 0) 175 return ret; 176 177 hw->ctrl = ctrl; 178 179 return 0; 180 } 181 182 static int sc18is602_check_transfer(struct spi_device *spi, 183 struct spi_transfer *t, int tlen) 184 { 185 if (t && t->len + tlen > SC18IS602_BUFSIZ) 186 return -EINVAL; 187 188 return 0; 189 } 190 191 static int sc18is602_transfer_one(struct spi_master *master, 192 struct spi_message *m) 193 { 194 struct sc18is602 *hw = spi_master_get_devdata(master); 195 struct spi_device *spi = m->spi; 196 struct spi_transfer *t; 197 int status = 0; 198 199 hw->tlen = 0; 200 list_for_each_entry(t, &m->transfers, transfer_list) { 201 bool do_transfer; 202 203 status = sc18is602_check_transfer(spi, t, hw->tlen); 204 if (status < 0) 205 break; 206 207 status = sc18is602_setup_transfer(hw, t->speed_hz, spi->mode); 208 if (status < 0) 209 break; 210 211 do_transfer = t->cs_change || list_is_last(&t->transfer_list, 212 &m->transfers); 213 214 if (t->len) { 215 status = sc18is602_txrx(hw, m, t, do_transfer); 216 if (status < 0) 217 break; 218 m->actual_length += status; 219 } 220 status = 0; 221 222 if (t->delay_usecs) 223 udelay(t->delay_usecs); 224 } 225 m->status = status; 226 spi_finalize_current_message(master); 227 228 return status; 229 } 230 231 static int sc18is602_setup(struct spi_device *spi) 232 { 233 struct sc18is602 *hw = spi_master_get_devdata(spi->master); 234 235 /* SC18IS602 does not support CS2 */ 236 if (hw->id == sc18is602 && spi->chip_select == 2) 237 return -ENXIO; 238 239 return 0; 240 } 241 242 static int sc18is602_probe(struct i2c_client *client, 243 const struct i2c_device_id *id) 244 { 245 struct device *dev = &client->dev; 246 struct device_node *np = dev->of_node; 247 struct sc18is602_platform_data *pdata = dev_get_platdata(dev); 248 struct sc18is602 *hw; 249 struct spi_master *master; 250 int error; 251 252 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | 253 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) 254 return -EINVAL; 255 256 master = spi_alloc_master(dev, sizeof(struct sc18is602)); 257 if (!master) 258 return -ENOMEM; 259 260 hw = spi_master_get_devdata(master); 261 i2c_set_clientdata(client, hw); 262 263 /* assert reset and then release */ 264 hw->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); 265 if (IS_ERR(hw->reset)) 266 return PTR_ERR(hw->reset); 267 gpiod_set_value_cansleep(hw->reset, 0); 268 269 hw->master = master; 270 hw->client = client; 271 hw->dev = dev; 272 hw->ctrl = 0xff; 273 274 hw->id = id->driver_data; 275 276 switch (hw->id) { 277 case sc18is602: 278 case sc18is602b: 279 master->num_chipselect = 4; 280 hw->freq = SC18IS602_CLOCK; 281 break; 282 case sc18is603: 283 master->num_chipselect = 2; 284 if (pdata) { 285 hw->freq = pdata->clock_frequency; 286 } else { 287 const __be32 *val; 288 int len; 289 290 val = of_get_property(np, "clock-frequency", &len); 291 if (val && len >= sizeof(__be32)) 292 hw->freq = be32_to_cpup(val); 293 } 294 if (!hw->freq) 295 hw->freq = SC18IS602_CLOCK; 296 break; 297 } 298 master->bus_num = np ? -1 : client->adapter->nr; 299 master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST; 300 master->bits_per_word_mask = SPI_BPW_MASK(8); 301 master->setup = sc18is602_setup; 302 master->transfer_one_message = sc18is602_transfer_one; 303 master->dev.of_node = np; 304 master->min_speed_hz = hw->freq / 128; 305 master->max_speed_hz = hw->freq / 4; 306 307 error = devm_spi_register_master(dev, master); 308 if (error) 309 goto error_reg; 310 311 return 0; 312 313 error_reg: 314 spi_master_put(master); 315 return error; 316 } 317 318 static const struct i2c_device_id sc18is602_id[] = { 319 { "sc18is602", sc18is602 }, 320 { "sc18is602b", sc18is602b }, 321 { "sc18is603", sc18is603 }, 322 { } 323 }; 324 MODULE_DEVICE_TABLE(i2c, sc18is602_id); 325 326 static struct i2c_driver sc18is602_driver = { 327 .driver = { 328 .name = "sc18is602", 329 }, 330 .probe = sc18is602_probe, 331 .id_table = sc18is602_id, 332 }; 333 334 module_i2c_driver(sc18is602_driver); 335 336 MODULE_DESCRIPTION("SC18IC602/603 SPI Master Driver"); 337 MODULE_AUTHOR("Guenter Roeck"); 338 MODULE_LICENSE("GPL"); 339