1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * NXP SC18IS602/603 SPI driver 4 * 5 * Copyright (C) Guenter Roeck <linux@roeck-us.net> 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/err.h> 10 #include <linux/module.h> 11 #include <linux/spi/spi.h> 12 #include <linux/i2c.h> 13 #include <linux/delay.h> 14 #include <linux/pm_runtime.h> 15 #include <linux/of_device.h> 16 #include <linux/of.h> 17 #include <linux/platform_data/sc18is602.h> 18 #include <linux/gpio/consumer.h> 19 20 enum chips { sc18is602, sc18is602b, sc18is603 }; 21 22 #define SC18IS602_BUFSIZ 200 23 #define SC18IS602_CLOCK 7372000 24 25 #define SC18IS602_MODE_CPHA BIT(2) 26 #define SC18IS602_MODE_CPOL BIT(3) 27 #define SC18IS602_MODE_LSB_FIRST BIT(5) 28 #define SC18IS602_MODE_CLOCK_DIV_4 0x0 29 #define SC18IS602_MODE_CLOCK_DIV_16 0x1 30 #define SC18IS602_MODE_CLOCK_DIV_64 0x2 31 #define SC18IS602_MODE_CLOCK_DIV_128 0x3 32 33 struct sc18is602 { 34 struct spi_master *master; 35 struct device *dev; 36 u8 ctrl; 37 u32 freq; 38 u32 speed; 39 40 /* I2C data */ 41 struct i2c_client *client; 42 enum chips id; 43 u8 buffer[SC18IS602_BUFSIZ + 1]; 44 int tlen; /* Data queued for tx in buffer */ 45 int rindex; /* Receive data index in buffer */ 46 47 struct gpio_desc *reset; 48 }; 49 50 static int sc18is602_wait_ready(struct sc18is602 *hw, int len) 51 { 52 int i, err; 53 int usecs = 1000000 * len / hw->speed + 1; 54 u8 dummy[1]; 55 56 for (i = 0; i < 10; i++) { 57 err = i2c_master_recv(hw->client, dummy, 1); 58 if (err >= 0) 59 return 0; 60 usleep_range(usecs, usecs * 2); 61 } 62 return -ETIMEDOUT; 63 } 64 65 static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg, 66 struct spi_transfer *t, bool do_transfer) 67 { 68 unsigned int len = t->len; 69 int ret; 70 71 if (hw->tlen == 0) { 72 /* First byte (I2C command) is chip select */ 73 hw->buffer[0] = 1 << msg->spi->chip_select; 74 hw->tlen = 1; 75 hw->rindex = 0; 76 } 77 /* 78 * We can not immediately send data to the chip, since each I2C message 79 * resembles a full SPI message (from CS active to CS inactive). 80 * Enqueue messages up to the first read or until do_transfer is true. 81 */ 82 if (t->tx_buf) { 83 memcpy(&hw->buffer[hw->tlen], t->tx_buf, len); 84 hw->tlen += len; 85 if (t->rx_buf) 86 do_transfer = true; 87 else 88 hw->rindex = hw->tlen - 1; 89 } else if (t->rx_buf) { 90 /* 91 * For receive-only transfers we still need to perform a dummy 92 * write to receive data from the SPI chip. 93 * Read data starts at the end of transmit data (minus 1 to 94 * account for CS). 95 */ 96 hw->rindex = hw->tlen - 1; 97 memset(&hw->buffer[hw->tlen], 0, len); 98 hw->tlen += len; 99 do_transfer = true; 100 } 101 102 if (do_transfer && hw->tlen > 1) { 103 ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ); 104 if (ret < 0) 105 return ret; 106 ret = i2c_master_send(hw->client, hw->buffer, hw->tlen); 107 if (ret < 0) 108 return ret; 109 if (ret != hw->tlen) 110 return -EIO; 111 112 if (t->rx_buf) { 113 int rlen = hw->rindex + len; 114 115 ret = sc18is602_wait_ready(hw, hw->tlen); 116 if (ret < 0) 117 return ret; 118 ret = i2c_master_recv(hw->client, hw->buffer, rlen); 119 if (ret < 0) 120 return ret; 121 if (ret != rlen) 122 return -EIO; 123 memcpy(t->rx_buf, &hw->buffer[hw->rindex], len); 124 } 125 hw->tlen = 0; 126 } 127 return len; 128 } 129 130 static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode) 131 { 132 u8 ctrl = 0; 133 int ret; 134 135 if (mode & SPI_CPHA) 136 ctrl |= SC18IS602_MODE_CPHA; 137 if (mode & SPI_CPOL) 138 ctrl |= SC18IS602_MODE_CPOL; 139 if (mode & SPI_LSB_FIRST) 140 ctrl |= SC18IS602_MODE_LSB_FIRST; 141 142 /* Find the closest clock speed */ 143 if (hz >= hw->freq / 4) { 144 ctrl |= SC18IS602_MODE_CLOCK_DIV_4; 145 hw->speed = hw->freq / 4; 146 } else if (hz >= hw->freq / 16) { 147 ctrl |= SC18IS602_MODE_CLOCK_DIV_16; 148 hw->speed = hw->freq / 16; 149 } else if (hz >= hw->freq / 64) { 150 ctrl |= SC18IS602_MODE_CLOCK_DIV_64; 151 hw->speed = hw->freq / 64; 152 } else { 153 ctrl |= SC18IS602_MODE_CLOCK_DIV_128; 154 hw->speed = hw->freq / 128; 155 } 156 157 /* 158 * Don't do anything if the control value did not change. The initial 159 * value of 0xff for hw->ctrl ensures that the correct mode will be set 160 * with the first call to this function. 161 */ 162 if (ctrl == hw->ctrl) 163 return 0; 164 165 ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl); 166 if (ret < 0) 167 return ret; 168 169 hw->ctrl = ctrl; 170 171 return 0; 172 } 173 174 static int sc18is602_check_transfer(struct spi_device *spi, 175 struct spi_transfer *t, int tlen) 176 { 177 if (t && t->len + tlen > SC18IS602_BUFSIZ) 178 return -EINVAL; 179 180 return 0; 181 } 182 183 static int sc18is602_transfer_one(struct spi_master *master, 184 struct spi_message *m) 185 { 186 struct sc18is602 *hw = spi_master_get_devdata(master); 187 struct spi_device *spi = m->spi; 188 struct spi_transfer *t; 189 int status = 0; 190 191 hw->tlen = 0; 192 list_for_each_entry(t, &m->transfers, transfer_list) { 193 bool do_transfer; 194 195 status = sc18is602_check_transfer(spi, t, hw->tlen); 196 if (status < 0) 197 break; 198 199 status = sc18is602_setup_transfer(hw, t->speed_hz, spi->mode); 200 if (status < 0) 201 break; 202 203 do_transfer = t->cs_change || list_is_last(&t->transfer_list, 204 &m->transfers); 205 206 if (t->len) { 207 status = sc18is602_txrx(hw, m, t, do_transfer); 208 if (status < 0) 209 break; 210 m->actual_length += status; 211 } 212 status = 0; 213 214 spi_transfer_delay_exec(t); 215 } 216 m->status = status; 217 spi_finalize_current_message(master); 218 219 return status; 220 } 221 222 static int sc18is602_setup(struct spi_device *spi) 223 { 224 struct sc18is602 *hw = spi_master_get_devdata(spi->master); 225 226 /* SC18IS602 does not support CS2 */ 227 if (hw->id == sc18is602 && spi->chip_select == 2) 228 return -ENXIO; 229 230 return 0; 231 } 232 233 static int sc18is602_probe(struct i2c_client *client, 234 const struct i2c_device_id *id) 235 { 236 struct device *dev = &client->dev; 237 struct device_node *np = dev->of_node; 238 struct sc18is602_platform_data *pdata = dev_get_platdata(dev); 239 struct sc18is602 *hw; 240 struct spi_master *master; 241 242 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | 243 I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) 244 return -EINVAL; 245 246 master = devm_spi_alloc_master(dev, sizeof(struct sc18is602)); 247 if (!master) 248 return -ENOMEM; 249 250 hw = spi_master_get_devdata(master); 251 i2c_set_clientdata(client, hw); 252 253 /* assert reset and then release */ 254 hw->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); 255 if (IS_ERR(hw->reset)) 256 return PTR_ERR(hw->reset); 257 gpiod_set_value_cansleep(hw->reset, 0); 258 259 hw->master = master; 260 hw->client = client; 261 hw->dev = dev; 262 hw->ctrl = 0xff; 263 264 if (client->dev.of_node) 265 hw->id = (enum chips)of_device_get_match_data(&client->dev); 266 else 267 hw->id = id->driver_data; 268 269 switch (hw->id) { 270 case sc18is602: 271 case sc18is602b: 272 master->num_chipselect = 4; 273 hw->freq = SC18IS602_CLOCK; 274 break; 275 case sc18is603: 276 master->num_chipselect = 2; 277 if (pdata) { 278 hw->freq = pdata->clock_frequency; 279 } else { 280 const __be32 *val; 281 int len; 282 283 val = of_get_property(np, "clock-frequency", &len); 284 if (val && len >= sizeof(__be32)) 285 hw->freq = be32_to_cpup(val); 286 } 287 if (!hw->freq) 288 hw->freq = SC18IS602_CLOCK; 289 break; 290 } 291 master->bus_num = np ? -1 : client->adapter->nr; 292 master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST; 293 master->bits_per_word_mask = SPI_BPW_MASK(8); 294 master->setup = sc18is602_setup; 295 master->transfer_one_message = sc18is602_transfer_one; 296 master->dev.of_node = np; 297 master->min_speed_hz = hw->freq / 128; 298 master->max_speed_hz = hw->freq / 4; 299 300 return devm_spi_register_master(dev, master); 301 } 302 303 static const struct i2c_device_id sc18is602_id[] = { 304 { "sc18is602", sc18is602 }, 305 { "sc18is602b", sc18is602b }, 306 { "sc18is603", sc18is603 }, 307 { } 308 }; 309 MODULE_DEVICE_TABLE(i2c, sc18is602_id); 310 311 static const struct of_device_id sc18is602_of_match[] = { 312 { 313 .compatible = "nxp,sc18is602", 314 .data = (void *)sc18is602 315 }, 316 { 317 .compatible = "nxp,sc18is602b", 318 .data = (void *)sc18is602b 319 }, 320 { 321 .compatible = "nxp,sc18is603", 322 .data = (void *)sc18is603 323 }, 324 { }, 325 }; 326 MODULE_DEVICE_TABLE(of, sc18is602_of_match); 327 328 static struct i2c_driver sc18is602_driver = { 329 .driver = { 330 .name = "sc18is602", 331 .of_match_table = of_match_ptr(sc18is602_of_match), 332 }, 333 .probe = sc18is602_probe, 334 .id_table = sc18is602_id, 335 }; 336 337 module_i2c_driver(sc18is602_driver); 338 339 MODULE_DESCRIPTION("SC18IS602/603 SPI Master Driver"); 340 MODULE_AUTHOR("Guenter Roeck"); 341 MODULE_LICENSE("GPL"); 342