xref: /openbmc/linux/drivers/spi/spi-sc18is602.c (revision 82a77923)
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