1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2017-2020 Jacopo Mondi
4  * Copyright (C) 2017-2020 Kieran Bingham
5  * Copyright (C) 2017-2020 Laurent Pinchart
6  * Copyright (C) 2017-2020 Niklas Söderlund
7  * Copyright (C) 2016 Renesas Electronics Corporation
8  * Copyright (C) 2015 Cogent Embedded, Inc.
9  *
10  * This file exports functions to control the Maxim MAX9271 GMSL serializer
11  * chip. This is not a self-contained driver, as MAX9271 is usually embedded in
12  * camera modules with at least one image sensor and optional additional
13  * components, such as uController units or ISPs/DSPs.
14  *
15  * Drivers for the camera modules (i.e. rdacm20/21) are expected to use
16  * functions exported from this library driver to maximize code re-use.
17  */
18 
19 #include <linux/delay.h>
20 #include <linux/i2c.h>
21 #include <linux/module.h>
22 
23 #include "max9271.h"
24 
max9271_read(struct max9271_device * dev,u8 reg)25 static int max9271_read(struct max9271_device *dev, u8 reg)
26 {
27 	int ret;
28 
29 	dev_dbg(&dev->client->dev, "%s(0x%02x)\n", __func__, reg);
30 
31 	ret = i2c_smbus_read_byte_data(dev->client, reg);
32 	if (ret < 0)
33 		dev_dbg(&dev->client->dev,
34 			"%s: register 0x%02x read failed (%d)\n",
35 			__func__, reg, ret);
36 
37 	return ret;
38 }
39 
max9271_write(struct max9271_device * dev,u8 reg,u8 val)40 static int max9271_write(struct max9271_device *dev, u8 reg, u8 val)
41 {
42 	int ret;
43 
44 	dev_dbg(&dev->client->dev, "%s(0x%02x, 0x%02x)\n", __func__, reg, val);
45 
46 	ret = i2c_smbus_write_byte_data(dev->client, reg, val);
47 	if (ret < 0)
48 		dev_err(&dev->client->dev,
49 			"%s: register 0x%02x write failed (%d)\n",
50 			__func__, reg, ret);
51 
52 	return ret;
53 }
54 
55 /*
56  * max9271_pclk_detect() - Detect valid pixel clock from image sensor
57  *
58  * Wait up to 10ms for a valid pixel clock.
59  *
60  * Returns 0 for success, < 0 for pixel clock not properly detected
61  */
max9271_pclk_detect(struct max9271_device * dev)62 static int max9271_pclk_detect(struct max9271_device *dev)
63 {
64 	unsigned int i;
65 	int ret;
66 
67 	for (i = 0; i < 100; i++) {
68 		ret = max9271_read(dev, 0x15);
69 		if (ret < 0)
70 			return ret;
71 
72 		if (ret & MAX9271_PCLKDET)
73 			return 0;
74 
75 		usleep_range(50, 100);
76 	}
77 
78 	dev_err(&dev->client->dev, "Unable to detect valid pixel clock\n");
79 
80 	return -EIO;
81 }
82 
max9271_wake_up(struct max9271_device * dev)83 void max9271_wake_up(struct max9271_device *dev)
84 {
85 	/*
86 	 * Use the chip default address as this function has to be called
87 	 * before any other one.
88 	 */
89 	dev->client->addr = MAX9271_DEFAULT_ADDR;
90 	i2c_smbus_read_byte(dev->client);
91 	usleep_range(5000, 8000);
92 }
93 EXPORT_SYMBOL_GPL(max9271_wake_up);
94 
max9271_set_serial_link(struct max9271_device * dev,bool enable)95 int max9271_set_serial_link(struct max9271_device *dev, bool enable)
96 {
97 	int ret;
98 	u8 val = MAX9271_REVCCEN | MAX9271_FWDCCEN;
99 
100 	if (enable) {
101 		ret = max9271_pclk_detect(dev);
102 		if (ret)
103 			return ret;
104 
105 		val |= MAX9271_SEREN;
106 	} else {
107 		val |= MAX9271_CLINKEN;
108 	}
109 
110 	/*
111 	 * The serializer temporarily disables the reverse control channel for
112 	 * 350µs after starting/stopping the forward serial link, but the
113 	 * deserializer synchronization time isn't clearly documented.
114 	 *
115 	 * According to the serializer datasheet we should wait 3ms, while
116 	 * according to the deserializer datasheet we should wait 5ms.
117 	 *
118 	 * Short delays here appear to show bit-errors in the writes following.
119 	 * Therefore a conservative delay seems best here.
120 	 */
121 	ret = max9271_write(dev, 0x04, val);
122 	if (ret < 0)
123 		return ret;
124 
125 	usleep_range(5000, 8000);
126 
127 	return 0;
128 }
129 EXPORT_SYMBOL_GPL(max9271_set_serial_link);
130 
max9271_configure_i2c(struct max9271_device * dev,u8 i2c_config)131 int max9271_configure_i2c(struct max9271_device *dev, u8 i2c_config)
132 {
133 	int ret;
134 
135 	ret = max9271_write(dev, 0x0d, i2c_config);
136 	if (ret < 0)
137 		return ret;
138 
139 	/* The delay required after an I2C bus configuration change is not
140 	 * characterized in the serializer manual. Sleep up to 5msec to
141 	 * stay safe.
142 	 */
143 	usleep_range(3500, 5000);
144 
145 	return 0;
146 }
147 EXPORT_SYMBOL_GPL(max9271_configure_i2c);
148 
max9271_set_high_threshold(struct max9271_device * dev,bool enable)149 int max9271_set_high_threshold(struct max9271_device *dev, bool enable)
150 {
151 	int ret;
152 
153 	ret = max9271_read(dev, 0x08);
154 	if (ret < 0)
155 		return ret;
156 
157 	/*
158 	 * Enable or disable reverse channel high threshold to increase
159 	 * immunity to power supply noise.
160 	 */
161 	ret = max9271_write(dev, 0x08, enable ? ret | BIT(0) : ret & ~BIT(0));
162 	if (ret < 0)
163 		return ret;
164 
165 	usleep_range(2000, 2500);
166 
167 	return 0;
168 }
169 EXPORT_SYMBOL_GPL(max9271_set_high_threshold);
170 
max9271_configure_gmsl_link(struct max9271_device * dev)171 int max9271_configure_gmsl_link(struct max9271_device *dev)
172 {
173 	int ret;
174 
175 	/*
176 	 * Configure the GMSL link:
177 	 *
178 	 * - Double input mode, high data rate, 24-bit mode
179 	 * - Latch input data on PCLKIN rising edge
180 	 * - Enable HS/VS encoding
181 	 * - 1-bit parity error detection
182 	 *
183 	 * TODO: Make the GMSL link configuration parametric.
184 	 */
185 	ret = max9271_write(dev, 0x07, MAX9271_DBL | MAX9271_HVEN |
186 			    MAX9271_EDC_1BIT_PARITY);
187 	if (ret < 0)
188 		return ret;
189 
190 	usleep_range(5000, 8000);
191 
192 	/*
193 	 * Adjust spread spectrum to +4% and auto-detect pixel clock
194 	 * and serial link rate.
195 	 */
196 	ret = max9271_write(dev, 0x02,
197 			    MAX9271_SPREAD_SPECT_4 | MAX9271_R02_RES |
198 			    MAX9271_PCLK_AUTODETECT |
199 			    MAX9271_SERIAL_AUTODETECT);
200 	if (ret < 0)
201 		return ret;
202 
203 	usleep_range(5000, 8000);
204 
205 	return 0;
206 }
207 EXPORT_SYMBOL_GPL(max9271_configure_gmsl_link);
208 
max9271_set_gpios(struct max9271_device * dev,u8 gpio_mask)209 int max9271_set_gpios(struct max9271_device *dev, u8 gpio_mask)
210 {
211 	int ret;
212 
213 	ret = max9271_read(dev, 0x0f);
214 	if (ret < 0)
215 		return 0;
216 
217 	ret |= gpio_mask;
218 	ret = max9271_write(dev, 0x0f, ret);
219 	if (ret < 0) {
220 		dev_err(&dev->client->dev, "Failed to set gpio (%d)\n", ret);
221 		return ret;
222 	}
223 
224 	usleep_range(3500, 5000);
225 
226 	return 0;
227 }
228 EXPORT_SYMBOL_GPL(max9271_set_gpios);
229 
max9271_clear_gpios(struct max9271_device * dev,u8 gpio_mask)230 int max9271_clear_gpios(struct max9271_device *dev, u8 gpio_mask)
231 {
232 	int ret;
233 
234 	ret = max9271_read(dev, 0x0f);
235 	if (ret < 0)
236 		return 0;
237 
238 	ret &= ~gpio_mask;
239 	ret = max9271_write(dev, 0x0f, ret);
240 	if (ret < 0) {
241 		dev_err(&dev->client->dev, "Failed to clear gpio (%d)\n", ret);
242 		return ret;
243 	}
244 
245 	usleep_range(3500, 5000);
246 
247 	return 0;
248 }
249 EXPORT_SYMBOL_GPL(max9271_clear_gpios);
250 
max9271_enable_gpios(struct max9271_device * dev,u8 gpio_mask)251 int max9271_enable_gpios(struct max9271_device *dev, u8 gpio_mask)
252 {
253 	int ret;
254 
255 	ret = max9271_read(dev, 0x0e);
256 	if (ret < 0)
257 		return 0;
258 
259 	/* BIT(0) reserved: GPO is always enabled. */
260 	ret |= (gpio_mask & ~BIT(0));
261 	ret = max9271_write(dev, 0x0e, ret);
262 	if (ret < 0) {
263 		dev_err(&dev->client->dev, "Failed to enable gpio (%d)\n", ret);
264 		return ret;
265 	}
266 
267 	usleep_range(3500, 5000);
268 
269 	return 0;
270 }
271 EXPORT_SYMBOL_GPL(max9271_enable_gpios);
272 
max9271_disable_gpios(struct max9271_device * dev,u8 gpio_mask)273 int max9271_disable_gpios(struct max9271_device *dev, u8 gpio_mask)
274 {
275 	int ret;
276 
277 	ret = max9271_read(dev, 0x0e);
278 	if (ret < 0)
279 		return 0;
280 
281 	/* BIT(0) reserved: GPO cannot be disabled */
282 	ret &= ~(gpio_mask | BIT(0));
283 	ret = max9271_write(dev, 0x0e, ret);
284 	if (ret < 0) {
285 		dev_err(&dev->client->dev, "Failed to disable gpio (%d)\n", ret);
286 		return ret;
287 	}
288 
289 	usleep_range(3500, 5000);
290 
291 	return 0;
292 }
293 EXPORT_SYMBOL_GPL(max9271_disable_gpios);
294 
max9271_verify_id(struct max9271_device * dev)295 int max9271_verify_id(struct max9271_device *dev)
296 {
297 	int ret;
298 
299 	ret = max9271_read(dev, 0x1e);
300 	if (ret < 0) {
301 		dev_err(&dev->client->dev, "MAX9271 ID read failed (%d)\n",
302 			ret);
303 		return ret;
304 	}
305 
306 	if (ret != MAX9271_ID) {
307 		dev_err(&dev->client->dev, "MAX9271 ID mismatch (0x%02x)\n",
308 			ret);
309 		return -ENXIO;
310 	}
311 
312 	return 0;
313 }
314 EXPORT_SYMBOL_GPL(max9271_verify_id);
315 
max9271_set_address(struct max9271_device * dev,u8 addr)316 int max9271_set_address(struct max9271_device *dev, u8 addr)
317 {
318 	int ret;
319 
320 	ret = max9271_write(dev, 0x00, addr << 1);
321 	if (ret < 0) {
322 		dev_err(&dev->client->dev,
323 			"MAX9271 I2C address change failed (%d)\n", ret);
324 		return ret;
325 	}
326 	usleep_range(3500, 5000);
327 
328 	return 0;
329 }
330 EXPORT_SYMBOL_GPL(max9271_set_address);
331 
max9271_set_deserializer_address(struct max9271_device * dev,u8 addr)332 int max9271_set_deserializer_address(struct max9271_device *dev, u8 addr)
333 {
334 	int ret;
335 
336 	ret = max9271_write(dev, 0x01, addr << 1);
337 	if (ret < 0) {
338 		dev_err(&dev->client->dev,
339 			"MAX9271 deserializer address set failed (%d)\n", ret);
340 		return ret;
341 	}
342 	usleep_range(3500, 5000);
343 
344 	return 0;
345 }
346 EXPORT_SYMBOL_GPL(max9271_set_deserializer_address);
347 
max9271_set_translation(struct max9271_device * dev,u8 source,u8 dest)348 int max9271_set_translation(struct max9271_device *dev, u8 source, u8 dest)
349 {
350 	int ret;
351 
352 	ret = max9271_write(dev, 0x09, source << 1);
353 	if (ret < 0) {
354 		dev_err(&dev->client->dev,
355 			"MAX9271 I2C translation setup failed (%d)\n", ret);
356 		return ret;
357 	}
358 	usleep_range(3500, 5000);
359 
360 	ret = max9271_write(dev, 0x0a, dest << 1);
361 	if (ret < 0) {
362 		dev_err(&dev->client->dev,
363 			"MAX9271 I2C translation setup failed (%d)\n", ret);
364 		return ret;
365 	}
366 	usleep_range(3500, 5000);
367 
368 	return 0;
369 }
370 EXPORT_SYMBOL_GPL(max9271_set_translation);
371 
372 MODULE_DESCRIPTION("Maxim MAX9271 GMSL Serializer");
373 MODULE_AUTHOR("Jacopo Mondi");
374 MODULE_LICENSE("GPL v2");
375