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Guenter Roeck3ce88592012-08-18 09:06:27 -07001/*
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.
Guenter Roeck3ce88592012-08-18 09:06:27 -070015 */
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
27enum 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
40struct 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
55static 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
70static 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
135static 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
179static int sc18is602_check_transfer(struct spi_device *spi,
180 struct spi_transfer *t, int tlen)
181{
Guenter Roeck3ce88592012-08-18 09:06:27 -0700182 if (t && t->len + tlen > SC18IS602_BUFSIZ)
183 return -EINVAL;
184
Guenter Roeck3ce88592012-08-18 09:06:27 -0700185 return 0;
186}
187
188static 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
Guenter Roeck3ce88592012-08-18 09:06:27 -0700196 hw->tlen = 0;
197 list_for_each_entry(t, &m->transfers, transfer_list) {
Guenter Roeck3ce88592012-08-18 09:06:27 -0700198 bool do_transfer;
199
200 status = sc18is602_check_transfer(spi, t, hw->tlen);
201 if (status < 0)
202 break;
203
Axel Lin09e99bc2014-02-28 18:39:33 +0800204 status = sc18is602_setup_transfer(hw, t->speed_hz, spi->mode);
Guenter Roeck3ce88592012-08-18 09:06:27 -0700205 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 }
Guenter Roeck3ce88592012-08-18 09:06:27 -0700222 m->status = status;
223 spi_finalize_current_message(master);
224
225 return status;
226}
227
Axel Linc5c67e32014-02-11 20:54:17 +0800228static 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
Guenter Roeck3ce88592012-08-18 09:06:27 -0700239static 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))
Guenter Roeck58ed90d2012-08-22 17:28:55 -0700251 return -EINVAL;
Guenter Roeck3ce88592012-08-18 09:06:27 -0700252
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 }
Guenter Roeckb4e27542015-02-06 12:27:54 -0800289 master->bus_num = np ? -1 : client->adapter->nr;
Guenter Roeck3ce88592012-08-18 09:06:27 -0700290 master->mode_bits = SPI_CPHA | SPI_CPOL | SPI_LSB_FIRST;
Axel Lin463654c2014-01-17 18:00:42 +0800291 master->bits_per_word_mask = SPI_BPW_MASK(8);
Axel Linc5c67e32014-02-11 20:54:17 +0800292 master->setup = sc18is602_setup;
Guenter Roeck3ce88592012-08-18 09:06:27 -0700293 master->transfer_one_message = sc18is602_transfer_one;
294 master->dev.of_node = np;
Axel Lin09e99bc2014-02-28 18:39:33 +0800295 master->min_speed_hz = hw->freq / 128;
296 master->max_speed_hz = hw->freq / 4;
Guenter Roeck3ce88592012-08-18 09:06:27 -0700297
Jingoo Han15e09642013-12-04 14:14:30 +0900298 error = devm_spi_register_master(dev, master);
Guenter Roeck3ce88592012-08-18 09:06:27 -0700299 if (error)
300 goto error_reg;
301
302 return 0;
303
304error_reg:
305 spi_master_put(master);
306 return error;
307}
308
Guenter Roeck3ce88592012-08-18 09:06:27 -0700309static const struct i2c_device_id sc18is602_id[] = {
310 { "sc18is602", sc18is602 },
311 { "sc18is602b", sc18is602b },
312 { "sc18is603", sc18is603 },
313 { }
314};
315MODULE_DEVICE_TABLE(i2c, sc18is602_id);
316
317static struct i2c_driver sc18is602_driver = {
318 .driver = {
319 .name = "sc18is602",
320 },
321 .probe = sc18is602_probe,
Guenter Roeck3ce88592012-08-18 09:06:27 -0700322 .id_table = sc18is602_id,
323};
324
325module_i2c_driver(sc18is602_driver);
326
327MODULE_DESCRIPTION("SC18IC602/603 SPI Master Driver");
328MODULE_AUTHOR("Guenter Roeck");
329MODULE_LICENSE("GPL");