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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_device.h> | |
25 | #include <linux/of.h> | |
26 | #include <linux/platform_data/sc18is602.h> | |
27 | #include <linux/gpio/consumer.h> | |
28 | ||
29 | enum chips { sc18is602, sc18is602b, sc18is603 }; | |
30 | ||
31 | #define SC18IS602_BUFSIZ 200 | |
32 | #define SC18IS602_CLOCK 7372000 | |
33 | ||
34 | #define SC18IS602_MODE_CPHA BIT(2) | |
35 | #define SC18IS602_MODE_CPOL BIT(3) | |
36 | #define SC18IS602_MODE_LSB_FIRST BIT(5) | |
37 | #define SC18IS602_MODE_CLOCK_DIV_4 0x0 | |
38 | #define SC18IS602_MODE_CLOCK_DIV_16 0x1 | |
39 | #define SC18IS602_MODE_CLOCK_DIV_64 0x2 | |
40 | #define SC18IS602_MODE_CLOCK_DIV_128 0x3 | |
41 | ||
42 | struct sc18is602 { | |
43 | struct spi_master *master; | |
44 | struct device *dev; | |
45 | u8 ctrl; | |
46 | u32 freq; | |
47 | u32 speed; | |
48 | ||
49 | /* I2C data */ | |
50 | struct i2c_client *client; | |
51 | enum chips id; | |
52 | u8 buffer[SC18IS602_BUFSIZ + 1]; | |
53 | int tlen; /* Data queued for tx in buffer */ | |
54 | int rindex; /* Receive data index in buffer */ | |
55 | ||
56 | struct gpio_desc *reset; | |
57 | }; | |
58 | ||
59 | static int sc18is602_wait_ready(struct sc18is602 *hw, int len) | |
60 | { | |
61 | int i, err; | |
62 | int usecs = 1000000 * len / hw->speed + 1; | |
63 | u8 dummy[1]; | |
64 | ||
65 | for (i = 0; i < 10; i++) { | |
66 | err = i2c_master_recv(hw->client, dummy, 1); | |
67 | if (err >= 0) | |
68 | return 0; | |
69 | usleep_range(usecs, usecs * 2); | |
70 | } | |
71 | return -ETIMEDOUT; | |
72 | } | |
73 | ||
74 | static int sc18is602_txrx(struct sc18is602 *hw, struct spi_message *msg, | |
75 | struct spi_transfer *t, bool do_transfer) | |
76 | { | |
77 | unsigned int len = t->len; | |
78 | int ret; | |
79 | ||
80 | if (hw->tlen == 0) { | |
81 | /* First byte (I2C command) is chip select */ | |
82 | hw->buffer[0] = 1 << msg->spi->chip_select; | |
83 | hw->tlen = 1; | |
84 | hw->rindex = 0; | |
85 | } | |
86 | /* | |
87 | * We can not immediately send data to the chip, since each I2C message | |
88 | * resembles a full SPI message (from CS active to CS inactive). | |
89 | * Enqueue messages up to the first read or until do_transfer is true. | |
90 | */ | |
91 | if (t->tx_buf) { | |
92 | memcpy(&hw->buffer[hw->tlen], t->tx_buf, len); | |
93 | hw->tlen += len; | |
94 | if (t->rx_buf) | |
95 | do_transfer = true; | |
96 | else | |
97 | hw->rindex = hw->tlen - 1; | |
98 | } else if (t->rx_buf) { | |
99 | /* | |
100 | * For receive-only transfers we still need to perform a dummy | |
101 | * write to receive data from the SPI chip. | |
102 | * Read data starts at the end of transmit data (minus 1 to | |
103 | * account for CS). | |
104 | */ | |
105 | hw->rindex = hw->tlen - 1; | |
106 | memset(&hw->buffer[hw->tlen], 0, len); | |
107 | hw->tlen += len; | |
108 | do_transfer = true; | |
109 | } | |
110 | ||
111 | if (do_transfer && hw->tlen > 1) { | |
112 | ret = sc18is602_wait_ready(hw, SC18IS602_BUFSIZ); | |
113 | if (ret < 0) | |
114 | return ret; | |
115 | ret = i2c_master_send(hw->client, hw->buffer, hw->tlen); | |
116 | if (ret < 0) | |
117 | return ret; | |
118 | if (ret != hw->tlen) | |
119 | return -EIO; | |
120 | ||
121 | if (t->rx_buf) { | |
122 | int rlen = hw->rindex + len; | |
123 | ||
124 | ret = sc18is602_wait_ready(hw, hw->tlen); | |
125 | if (ret < 0) | |
126 | return ret; | |
127 | ret = i2c_master_recv(hw->client, hw->buffer, rlen); | |
128 | if (ret < 0) | |
129 | return ret; | |
130 | if (ret != rlen) | |
131 | return -EIO; | |
132 | memcpy(t->rx_buf, &hw->buffer[hw->rindex], len); | |
133 | } | |
134 | hw->tlen = 0; | |
135 | } | |
136 | return len; | |
137 | } | |
138 | ||
139 | static int sc18is602_setup_transfer(struct sc18is602 *hw, u32 hz, u8 mode) | |
140 | { | |
141 | u8 ctrl = 0; | |
142 | int ret; | |
143 | ||
144 | if (mode & SPI_CPHA) | |
145 | ctrl |= SC18IS602_MODE_CPHA; | |
146 | if (mode & SPI_CPOL) | |
147 | ctrl |= SC18IS602_MODE_CPOL; | |
148 | if (mode & SPI_LSB_FIRST) | |
149 | ctrl |= SC18IS602_MODE_LSB_FIRST; | |
150 | ||
151 | /* Find the closest clock speed */ | |
152 | if (hz >= hw->freq / 4) { | |
153 | ctrl |= SC18IS602_MODE_CLOCK_DIV_4; | |
154 | hw->speed = hw->freq / 4; | |
155 | } else if (hz >= hw->freq / 16) { | |
156 | ctrl |= SC18IS602_MODE_CLOCK_DIV_16; | |
157 | hw->speed = hw->freq / 16; | |
158 | } else if (hz >= hw->freq / 64) { | |
159 | ctrl |= SC18IS602_MODE_CLOCK_DIV_64; | |
160 | hw->speed = hw->freq / 64; | |
161 | } else { | |
162 | ctrl |= SC18IS602_MODE_CLOCK_DIV_128; | |
163 | hw->speed = hw->freq / 128; | |
164 | } | |
165 | ||
166 | /* | |
167 | * Don't do anything if the control value did not change. The initial | |
168 | * value of 0xff for hw->ctrl ensures that the correct mode will be set | |
169 | * with the first call to this function. | |
170 | */ | |
171 | if (ctrl == hw->ctrl) | |
172 | return 0; | |
173 | ||
174 | ret = i2c_smbus_write_byte_data(hw->client, 0xf0, ctrl); | |
175 | if (ret < 0) | |
176 | return ret; | |
177 | ||
178 | hw->ctrl = ctrl; | |
179 | ||
180 | return 0; | |
181 | } | |
182 | ||
183 | static int sc18is602_check_transfer(struct spi_device *spi, | |
184 | struct spi_transfer *t, int tlen) | |
185 | { | |
186 | if (t && t->len + tlen > SC18IS602_BUFSIZ) | |
187 | return -EINVAL; | |
188 | ||
189 | return 0; | |
190 | } | |
191 | ||
192 | static int sc18is602_transfer_one(struct spi_master *master, | |
193 | struct spi_message *m) | |
194 | { | |
195 | struct sc18is602 *hw = spi_master_get_devdata(master); | |
196 | struct spi_device *spi = m->spi; | |
197 | struct spi_transfer *t; | |
198 | int status = 0; | |
199 | ||
200 | hw->tlen = 0; | |
201 | list_for_each_entry(t, &m->transfers, transfer_list) { | |
202 | bool do_transfer; | |
203 | ||
204 | status = sc18is602_check_transfer(spi, t, hw->tlen); | |
205 | if (status < 0) | |
206 | break; | |
207 | ||
208 | status = sc18is602_setup_transfer(hw, t->speed_hz, spi->mode); | |
209 | if (status < 0) | |
210 | break; | |
211 | ||
212 | do_transfer = t->cs_change || list_is_last(&t->transfer_list, | |
213 | &m->transfers); | |
214 | ||
215 | if (t->len) { | |
216 | status = sc18is602_txrx(hw, m, t, do_transfer); | |
217 | if (status < 0) | |
218 | break; | |
219 | m->actual_length += status; | |
220 | } | |
221 | status = 0; | |
222 | ||
223 | if (t->delay_usecs) | |
224 | udelay(t->delay_usecs); | |
225 | } | |
226 | m->status = status; | |
227 | spi_finalize_current_message(master); | |
228 | ||
229 | return status; | |
230 | } | |
231 | ||
232 | static int sc18is602_setup(struct spi_device *spi) | |
233 | { | |
234 | struct sc18is602 *hw = spi_master_get_devdata(spi->master); | |
235 | ||
236 | /* SC18IS602 does not support CS2 */ | |
237 | if (hw->id == sc18is602 && spi->chip_select == 2) | |
238 | return -ENXIO; | |
239 | ||
240 | return 0; | |
241 | } | |
242 | ||
243 | static int sc18is602_probe(struct i2c_client *client, | |
244 | const struct i2c_device_id *id) | |
245 | { | |
246 | struct device *dev = &client->dev; | |
247 | struct device_node *np = dev->of_node; | |
248 | struct sc18is602_platform_data *pdata = dev_get_platdata(dev); | |
249 | struct sc18is602 *hw; | |
250 | struct spi_master *master; | |
251 | int error; | |
252 | ||
253 | if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C | | |
254 | I2C_FUNC_SMBUS_WRITE_BYTE_DATA)) | |
255 | return -EINVAL; | |
256 | ||
257 | master = spi_alloc_master(dev, sizeof(struct sc18is602)); | |
258 | if (!master) | |
259 | return -ENOMEM; | |
260 | ||
261 | hw = spi_master_get_devdata(master); | |
262 | i2c_set_clientdata(client, hw); | |
263 | ||
264 | /* assert reset and then release */ | |
265 | hw->reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH); | |
266 | if (IS_ERR(hw->reset)) | |
267 | return PTR_ERR(hw->reset); | |
268 | gpiod_set_value_cansleep(hw->reset, 0); | |
269 | ||
270 | hw->master = master; | |
271 | hw->client = client; | |
272 | hw->dev = dev; | |
273 | hw->ctrl = 0xff; | |
274 | ||
275 | if (client->dev.of_node) | |
276 | hw->id = (enum chips)of_device_get_match_data(&client->dev); | |
277 | else | |
278 | hw->id = id->driver_data; | |
279 | ||
280 | switch (hw->id) { | |
281 | case sc18is602: | |
282 | case sc18is602b: | |
283 | master->num_chipselect = 4; | |
284 | hw->freq = SC18IS602_CLOCK; | |
285 | break; | |
286 | case sc18is603: | |
287 | master->num_chipselect = 2; | |
288 | if (pdata) { | |
289 | hw->freq = pdata->clock_frequency; | |
290 | } else { | |
291 | const __be32 *val; | |
292 | int len; | |
293 | ||
294 | val = of_get_property(np, "clock-frequency", &len); | |
295 | if (val && len >= sizeof(__be32)) | |
296 | hw->freq = be32_to_cpup(val); | |
297 | } | |
298 | if (!hw->freq) | |
299 | hw->freq = SC18IS602_CLOCK; | |
300 | break; | |
301 | } | |
302 | master->bus_num = np ? -1 : client->adapter->nr; | |
303 | master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST; | |
304 | master->bits_per_word_mask = SPI_BPW_MASK(8); | |
305 | master->setup = sc18is602_setup; | |
306 | master->transfer_one_message = sc18is602_transfer_one; | |
307 | master->dev.of_node = np; | |
308 | master->min_speed_hz = hw->freq / 128; | |
309 | master->max_speed_hz = hw->freq / 4; | |
310 | ||
311 | error = devm_spi_register_master(dev, master); | |
312 | if (error) | |
313 | goto error_reg; | |
314 | ||
315 | return 0; | |
316 | ||
317 | error_reg: | |
318 | spi_master_put(master); | |
319 | return error; | |
320 | } | |
321 | ||
322 | static const struct i2c_device_id sc18is602_id[] = { | |
323 | { "sc18is602", sc18is602 }, | |
324 | { "sc18is602b", sc18is602b }, | |
325 | { "sc18is603", sc18is603 }, | |
326 | { } | |
327 | }; | |
328 | MODULE_DEVICE_TABLE(i2c, sc18is602_id); | |
329 | ||
330 | static const struct of_device_id sc18is602_of_match[] = { | |
331 | { | |
332 | .compatible = "nxp,sc18is602", | |
333 | .data = (void *)sc18is602 | |
334 | }, | |
335 | { | |
336 | .compatible = "nxp,sc18is602b", | |
337 | .data = (void *)sc18is602b | |
338 | }, | |
339 | { | |
340 | .compatible = "nxp,sc18is603", | |
341 | .data = (void *)sc18is603 | |
342 | }, | |
343 | { }, | |
344 | }; | |
345 | MODULE_DEVICE_TABLE(of, sc18is602_of_match); | |
346 | ||
347 | static struct i2c_driver sc18is602_driver = { | |
348 | .driver = { | |
349 | .name = "sc18is602", | |
350 | .of_match_table = of_match_ptr(sc18is602_of_match), | |
351 | }, | |
352 | .probe = sc18is602_probe, | |
353 | .id_table = sc18is602_id, | |
354 | }; | |
355 | ||
356 | module_i2c_driver(sc18is602_driver); | |
357 | ||
358 | MODULE_DESCRIPTION("SC18IC602/603 SPI Master Driver"); | |
359 | MODULE_AUTHOR("Guenter Roeck"); | |
360 | MODULE_LICENSE("GPL"); |