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.h>
16 #include <linux/platform_data/sc18is602.h>
17 #include <linux/gpio/consumer.h>
18
19 enum chips { sc18is602, sc18is602b, sc18is603 };
20
21 #define SC18IS602_BUFSIZ 200
22 #define SC18IS602_CLOCK 7372000
23
24 #define SC18IS602_MODE_CPHA BIT(2)
25 #define SC18IS602_MODE_CPOL BIT(3)
26 #define SC18IS602_MODE_LSB_FIRST BIT(5)
27 #define SC18IS602_MODE_CLOCK_DIV_4 0x0
28 #define SC18IS602_MODE_CLOCK_DIV_16 0x1
29 #define SC18IS602_MODE_CLOCK_DIV_64 0x2
30 #define SC18IS602_MODE_CLOCK_DIV_128 0x3
31
32 struct sc18is602 {
33 struct spi_controller *host;
34 struct device *dev;
35 u8 ctrl;
36 u32 freq;
37 u32 speed;
38
39 /* I2C data */
40 struct i2c_client *client;
41 enum chips id;
42 u8 buffer[SC18IS602_BUFSIZ + 1];
43 int tlen; /* Data queued for tx in buffer */
44 int rindex; /* Receive data index in buffer */
45
46 struct gpio_desc *reset;
47 };
48
sc18is602_wait_ready(struct sc18is602 * hw,int len)49 static int sc18is602_wait_ready(struct sc18is602 *hw, int len)
50 {
51 int i, err;
52 int usecs = 1000000 * len / hw->speed + 1;
53 u8 dummy[1];
54
55 for (i = 0; i < 10; i++) {
56 err = i2c_master_recv(hw->client, dummy, 1);
57 if (err >= 0)
58 return 0;
59 usleep_range(usecs, usecs * 2);
60 }
61 return -ETIMEDOUT;
62 }
63
sc18is602_txrx(struct sc18is602 * hw,struct spi_message * msg,struct spi_transfer * t,bool do_transfer)64 static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg,
65 struct spi_transfer *t, bool do_transfer)
66 {
67 unsigned int len = t->len;
68 int ret;
69
70 if (hw->tlen == 0) {
71 /* First byte (I2C command) is chip select */
72 hw->buffer[0] = 1 << spi_get_chipselect(msg->spi, 0);
73 hw->tlen = 1;
74 hw->rindex = 0;
75 }
76 /*
77 * We can not immediately send data to the chip, since each I2C message
78 * resembles a full SPI message (from CS active to CS inactive).
79 * Enqueue messages up to the first read or until do_transfer is true.
80 */
81 if (t->tx_buf) {
82 memcpy(&hw->buffer[hw->tlen], t->tx_buf, len);
83 hw->tlen += len;
84 if (t->rx_buf)
85 do_transfer = true;
86 else
87 hw->rindex = hw->tlen - 1;
88 } else if (t->rx_buf) {
89 /*
90 * For receive-only transfers we still need to perform a dummy
91 * write to receive data from the SPI chip.
92 * Read data starts at the end of transmit data (minus 1 to
93 * account for CS).
94 */
95 hw->rindex = hw->tlen - 1;
96 memset(&hw->buffer[hw->tlen], 0, len);
97 hw->tlen += len;
98 do_transfer = true;
99 }
100
101 if (do_transfer && hw->tlen > 1) {
102 ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ);
103 if (ret < 0)
104 return ret;
105 ret = i2c_master_send(hw->client, hw->buffer, hw->tlen);
106 if (ret < 0)
107 return ret;
108 if (ret != hw->tlen)
109 return -EIO;
110
111 if (t->rx_buf) {
112 int rlen = hw->rindex + len;
113
114 ret = sc18is602_wait_ready(hw, hw->tlen);
115 if (ret < 0)
116 return ret;
117 ret = i2c_master_recv(hw->client, hw->buffer, rlen);
118 if (ret < 0)
119 return ret;
120 if (ret != rlen)
121 return -EIO;
122 memcpy(t->rx_buf, &hw->buffer[hw->rindex], len);
123 }
124 hw->tlen = 0;
125 }
126 return len;
127 }
128
sc18is602_setup_transfer(struct sc18is602 * hw,u32 hz,u8 mode)129 static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode)
130 {
131 u8 ctrl = 0;
132 int ret;
133
134 if (mode & SPI_CPHA)
135 ctrl |= SC18IS602_MODE_CPHA;
136 if (mode & SPI_CPOL)
137 ctrl |= SC18IS602_MODE_CPOL;
138 if (mode & SPI_LSB_FIRST)
139 ctrl |= SC18IS602_MODE_LSB_FIRST;
140
141 /* Find the closest clock speed */
142 if (hz >= hw->freq / 4) {
143 ctrl |= SC18IS602_MODE_CLOCK_DIV_4;
144 hw->speed = hw->freq / 4;
145 } else if (hz >= hw->freq / 16) {
146 ctrl |= SC18IS602_MODE_CLOCK_DIV_16;
147 hw->speed = hw->freq / 16;
148 } else if (hz >= hw->freq / 64) {
149 ctrl |= SC18IS602_MODE_CLOCK_DIV_64;
150 hw->speed = hw->freq / 64;
151 } else {
152 ctrl |= SC18IS602_MODE_CLOCK_DIV_128;
153 hw->speed = hw->freq / 128;
154 }
155
156 /*
157 * Don't do anything if the control value did not change. The initial
158 * value of 0xff for hw->ctrl ensures that the correct mode will be set
159 * with the first call to this function.
160 */
161 if (ctrl == hw->ctrl)
162 return 0;
163
164 ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl);
165 if (ret < 0)
166 return ret;
167
168 hw->ctrl = ctrl;
169
170 return 0;
171 }
172
sc18is602_check_transfer(struct spi_device * spi,struct spi_transfer * t,int tlen)173 static int sc18is602_check_transfer(struct spi_device *spi,
174 struct spi_transfer *t, int tlen)
175 {
176 if (t && t->len + tlen > SC18IS602_BUFSIZ + 1)
177 return -EINVAL;
178
179 return 0;
180 }
181
sc18is602_transfer_one(struct spi_controller * host,struct spi_message * m)182 static int sc18is602_transfer_one(struct spi_controller *host,
183 struct spi_message *m)
184 {
185 struct sc18is602 *hw = spi_controller_get_devdata(host);
186 struct spi_device *spi = m->spi;
187 struct spi_transfer *t;
188 int status = 0;
189
190 hw->tlen = 0;
191 list_for_each_entry(t, &m->transfers, transfer_list) {
192 bool do_transfer;
193
194 status = sc18is602_check_transfer(spi, t, hw->tlen);
195 if (status < 0)
196 break;
197
198 status = sc18is602_setup_transfer(hw, t->speed_hz, spi->mode);
199 if (status < 0)
200 break;
201
202 do_transfer = t->cs_change || list_is_last(&t->transfer_list,
203 &m->transfers);
204
205 if (t->len) {
206 status = sc18is602_txrx(hw, m, t, do_transfer);
207 if (status < 0)
208 break;
209 m->actual_length += status;
210 }
211 status = 0;
212
213 spi_transfer_delay_exec(t);
214 }
215 m->status = status;
216 spi_finalize_current_message(host);
217
218 return status;
219 }
220
sc18is602_max_transfer_size(struct spi_device * spi)221 static size_t sc18is602_max_transfer_size(struct spi_device *spi)
222 {
223 return SC18IS602_BUFSIZ;
224 }
225
sc18is602_setup(struct spi_device * spi)226 static int sc18is602_setup(struct spi_device *spi)
227 {
228 struct sc18is602 *hw = spi_controller_get_devdata(spi->controller);
229
230 /* SC18IS602 does not support CS2 */
231 if (hw->id == sc18is602 && (spi_get_chipselect(spi, 0) == 2))
232 return -ENXIO;
233
234 return 0;
235 }
236
sc18is602_probe(struct i2c_client * client)237 static int sc18is602_probe(struct i2c_client *client)
238 {
239 const struct i2c_device_id *id = i2c_client_get_device_id(client);
240 struct device *dev = &client->dev;
241 struct device_node *np = dev->of_node;
242 struct sc18is602_platform_data *pdata = dev_get_platdata(dev);
243 struct sc18is602 *hw;
244 struct spi_controller *host;
245
246 if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C |
247 I2C_FUNC_SMBUS_WRITE_BYTE_DATA))
248 return -EINVAL;
249
250 host = devm_spi_alloc_host(dev, sizeof(struct sc18is602));
251 if (!host)
252 return -ENOMEM;
253
254 hw = spi_controller_get_devdata(host);
255 i2c_set_clientdata(client, hw);
256
257 /* assert reset and then release */
258 hw->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
259 if (IS_ERR(hw->reset))
260 return PTR_ERR(hw->reset);
261 gpiod_set_value_cansleep(hw->reset, 0);
262
263 hw->host = host;
264 hw->client = client;
265 hw->dev = dev;
266 hw->ctrl = 0xff;
267
268 if (client->dev.of_node)
269 hw->id = (uintptr_t)of_device_get_match_data(&client->dev);
270 else
271 hw->id = id->driver_data;
272
273 switch (hw->id) {
274 case sc18is602:
275 case sc18is602b:
276 host->num_chipselect = 4;
277 hw->freq = SC18IS602_CLOCK;
278 break;
279 case sc18is603:
280 host->num_chipselect = 2;
281 if (pdata) {
282 hw->freq = pdata->clock_frequency;
283 } else {
284 const __be32 *val;
285 int len;
286
287 val = of_get_property(np, "clock-frequency", &len);
288 if (val && len >= sizeof(__be32))
289 hw->freq = be32_to_cpup(val);
290 }
291 if (!hw->freq)
292 hw->freq = SC18IS602_CLOCK;
293 break;
294 }
295 host->bus_num = np ? -1 : client->adapter->nr;
296 host->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;
297 host->bits_per_word_mask = SPI_BPW_MASK(8);
298 host->setup = sc18is602_setup;
299 host->transfer_one_message = sc18is602_transfer_one;
300 host->max_transfer_size = sc18is602_max_transfer_size;
301 host->max_message_size = sc18is602_max_transfer_size;
302 host->dev.of_node = np;
303 host->min_speed_hz = hw->freq / 128;
304 host->max_speed_hz = hw->freq / 4;
305
306 return devm_spi_register_controller(dev, host);
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 const struct of_device_id sc18is602_of_match[] __maybe_unused = {
318 {
319 .compatible = "nxp,sc18is602",
320 .data = (void *)sc18is602
321 },
322 {
323 .compatible = "nxp,sc18is602b",
324 .data = (void *)sc18is602b
325 },
326 {
327 .compatible = "nxp,sc18is603",
328 .data = (void *)sc18is603
329 },
330 { },
331 };
332 MODULE_DEVICE_TABLE(of, sc18is602_of_match);
333
334 static struct i2c_driver sc18is602_driver = {
335 .driver = {
336 .name = "sc18is602",
337 .of_match_table = of_match_ptr(sc18is602_of_match),
338 },
339 .probe = sc18is602_probe,
340 .id_table = sc18is602_id,
341 };
342
343 module_i2c_driver(sc18is602_driver);
344
345 MODULE_DESCRIPTION("SC18IS602/603 SPI Host Driver");
346 MODULE_AUTHOR("Guenter Roeck");
347 MODULE_LICENSE("GPL");
348