xref: /openbmc/linux/drivers/hwmon/ltc4245.c (revision be709d48)
1 /*
2  * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
3  *
4  * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
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; version 2 of the License.
9  *
10  * This driver is based on the ds1621 and ina209 drivers.
11  *
12  * Datasheet:
13  * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
14  */
15 
16 #include <linux/kernel.h>
17 #include <linux/module.h>
18 #include <linux/init.h>
19 #include <linux/bitops.h>
20 #include <linux/err.h>
21 #include <linux/slab.h>
22 #include <linux/i2c.h>
23 #include <linux/hwmon.h>
24 #include <linux/hwmon-sysfs.h>
25 #include <linux/jiffies.h>
26 #include <linux/platform_data/ltc4245.h>
27 
28 /* Here are names of the chip's registers (a.k.a. commands) */
29 enum ltc4245_cmd {
30 	LTC4245_STATUS			= 0x00, /* readonly */
31 	LTC4245_ALERT			= 0x01,
32 	LTC4245_CONTROL			= 0x02,
33 	LTC4245_ON			= 0x03,
34 	LTC4245_FAULT1			= 0x04,
35 	LTC4245_FAULT2			= 0x05,
36 	LTC4245_GPIO			= 0x06,
37 	LTC4245_ADCADR			= 0x07,
38 
39 	LTC4245_12VIN			= 0x10,
40 	LTC4245_12VSENSE		= 0x11,
41 	LTC4245_12VOUT			= 0x12,
42 	LTC4245_5VIN			= 0x13,
43 	LTC4245_5VSENSE			= 0x14,
44 	LTC4245_5VOUT			= 0x15,
45 	LTC4245_3VIN			= 0x16,
46 	LTC4245_3VSENSE			= 0x17,
47 	LTC4245_3VOUT			= 0x18,
48 	LTC4245_VEEIN			= 0x19,
49 	LTC4245_VEESENSE		= 0x1a,
50 	LTC4245_VEEOUT			= 0x1b,
51 	LTC4245_GPIOADC			= 0x1c,
52 };
53 
54 struct ltc4245_data {
55 	struct i2c_client *client;
56 
57 	struct mutex update_lock;
58 	bool valid;
59 	unsigned long last_updated; /* in jiffies */
60 
61 	/* Control registers */
62 	u8 cregs[0x08];
63 
64 	/* Voltage registers */
65 	u8 vregs[0x0d];
66 
67 	/* GPIO ADC registers */
68 	bool use_extra_gpios;
69 	int gpios[3];
70 };
71 
72 /*
73  * Update the readings from the GPIO pins. If the driver has been configured to
74  * sample all GPIO's as analog voltages, a round-robin sampling method is used.
75  * Otherwise, only the configured GPIO pin is sampled.
76  *
77  * LOCKING: must hold data->update_lock
78  */
79 static void ltc4245_update_gpios(struct device *dev)
80 {
81 	struct ltc4245_data *data = dev_get_drvdata(dev);
82 	struct i2c_client *client = data->client;
83 	u8 gpio_curr, gpio_next, gpio_reg;
84 	int i;
85 
86 	/* no extra gpio support, we're basically done */
87 	if (!data->use_extra_gpios) {
88 		data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
89 		return;
90 	}
91 
92 	/*
93 	 * If the last reading was too long ago, then we mark all old GPIO
94 	 * readings as stale by setting them to -EAGAIN
95 	 */
96 	if (time_after(jiffies, data->last_updated + 5 * HZ)) {
97 		for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
98 			data->gpios[i] = -EAGAIN;
99 	}
100 
101 	/*
102 	 * Get the current GPIO pin
103 	 *
104 	 * The datasheet calls these GPIO[1-3], but we'll calculate the zero
105 	 * based array index instead, and call them GPIO[0-2]. This is much
106 	 * easier to think about.
107 	 */
108 	gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
109 	if (gpio_curr > 0)
110 		gpio_curr -= 1;
111 
112 	/* Read the GPIO voltage from the GPIOADC register */
113 	data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];
114 
115 	/* Find the next GPIO pin to read */
116 	gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);
117 
118 	/*
119 	 * Calculate the correct setting for the GPIO register so it will
120 	 * sample the next GPIO pin
121 	 */
122 	gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);
123 
124 	/* Update the GPIO register */
125 	i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);
126 
127 	/* Update saved data */
128 	data->cregs[LTC4245_GPIO] = gpio_reg;
129 }
130 
131 static struct ltc4245_data *ltc4245_update_device(struct device *dev)
132 {
133 	struct ltc4245_data *data = dev_get_drvdata(dev);
134 	struct i2c_client *client = data->client;
135 	s32 val;
136 	int i;
137 
138 	mutex_lock(&data->update_lock);
139 
140 	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
141 
142 		/* Read control registers -- 0x00 to 0x07 */
143 		for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
144 			val = i2c_smbus_read_byte_data(client, i);
145 			if (unlikely(val < 0))
146 				data->cregs[i] = 0;
147 			else
148 				data->cregs[i] = val;
149 		}
150 
151 		/* Read voltage registers -- 0x10 to 0x1c */
152 		for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
153 			val = i2c_smbus_read_byte_data(client, i+0x10);
154 			if (unlikely(val < 0))
155 				data->vregs[i] = 0;
156 			else
157 				data->vregs[i] = val;
158 		}
159 
160 		/* Update GPIO readings */
161 		ltc4245_update_gpios(dev);
162 
163 		data->last_updated = jiffies;
164 		data->valid = true;
165 	}
166 
167 	mutex_unlock(&data->update_lock);
168 
169 	return data;
170 }
171 
172 /* Return the voltage from the given register in millivolts */
173 static int ltc4245_get_voltage(struct device *dev, u8 reg)
174 {
175 	struct ltc4245_data *data = ltc4245_update_device(dev);
176 	const u8 regval = data->vregs[reg - 0x10];
177 	u32 voltage = 0;
178 
179 	switch (reg) {
180 	case LTC4245_12VIN:
181 	case LTC4245_12VOUT:
182 		voltage = regval * 55;
183 		break;
184 	case LTC4245_5VIN:
185 	case LTC4245_5VOUT:
186 		voltage = regval * 22;
187 		break;
188 	case LTC4245_3VIN:
189 	case LTC4245_3VOUT:
190 		voltage = regval * 15;
191 		break;
192 	case LTC4245_VEEIN:
193 	case LTC4245_VEEOUT:
194 		voltage = regval * -55;
195 		break;
196 	case LTC4245_GPIOADC:
197 		voltage = regval * 10;
198 		break;
199 	default:
200 		/* If we get here, the developer messed up */
201 		WARN_ON_ONCE(1);
202 		break;
203 	}
204 
205 	return voltage;
206 }
207 
208 /* Return the current in the given sense register in milliAmperes */
209 static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
210 {
211 	struct ltc4245_data *data = ltc4245_update_device(dev);
212 	const u8 regval = data->vregs[reg - 0x10];
213 	unsigned int voltage;
214 	unsigned int curr;
215 
216 	/*
217 	 * The strange looking conversions that follow are fixed-point
218 	 * math, since we cannot do floating point in the kernel.
219 	 *
220 	 * Step 1: convert sense register to microVolts
221 	 * Step 2: convert voltage to milliAmperes
222 	 *
223 	 * If you play around with the V=IR equation, you come up with
224 	 * the following: X uV / Y mOhm == Z mA
225 	 *
226 	 * With the resistors that are fractions of a milliOhm, we multiply
227 	 * the voltage and resistance by 10, to shift the decimal point.
228 	 * Now we can use the normal division operator again.
229 	 */
230 
231 	switch (reg) {
232 	case LTC4245_12VSENSE:
233 		voltage = regval * 250; /* voltage in uV */
234 		curr = voltage / 50; /* sense resistor 50 mOhm */
235 		break;
236 	case LTC4245_5VSENSE:
237 		voltage = regval * 125; /* voltage in uV */
238 		curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
239 		break;
240 	case LTC4245_3VSENSE:
241 		voltage = regval * 125; /* voltage in uV */
242 		curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
243 		break;
244 	case LTC4245_VEESENSE:
245 		voltage = regval * 250; /* voltage in uV */
246 		curr = voltage / 100; /* sense resistor 100 mOhm */
247 		break;
248 	default:
249 		/* If we get here, the developer messed up */
250 		WARN_ON_ONCE(1);
251 		curr = 0;
252 		break;
253 	}
254 
255 	return curr;
256 }
257 
258 /* Map from voltage channel index to voltage register */
259 
260 static const s8 ltc4245_in_regs[] = {
261 	LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN,
262 	LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT,
263 };
264 
265 /* Map from current channel index to current register */
266 
267 static const s8 ltc4245_curr_regs[] = {
268 	LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE,
269 };
270 
271 static int ltc4245_read_curr(struct device *dev, u32 attr, int channel,
272 			     long *val)
273 {
274 	struct ltc4245_data *data = ltc4245_update_device(dev);
275 
276 	switch (attr) {
277 	case hwmon_curr_input:
278 		*val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
279 		return 0;
280 	case hwmon_curr_max_alarm:
281 		*val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4));
282 		return 0;
283 	default:
284 		return -EOPNOTSUPP;
285 	}
286 }
287 
288 static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val)
289 {
290 	struct ltc4245_data *data = ltc4245_update_device(dev);
291 
292 	switch (attr) {
293 	case hwmon_in_input:
294 		if (channel < 8) {
295 			*val = ltc4245_get_voltage(dev,
296 						ltc4245_in_regs[channel]);
297 		} else {
298 			int regval = data->gpios[channel - 8];
299 
300 			if (regval < 0)
301 				return regval;
302 			*val = regval * 10;
303 		}
304 		return 0;
305 	case hwmon_in_min_alarm:
306 		if (channel < 4)
307 			*val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel));
308 		else
309 			*val = !!(data->cregs[LTC4245_FAULT2] &
310 				  BIT(channel - 4));
311 		return 0;
312 	default:
313 		return -EOPNOTSUPP;
314 	}
315 }
316 
317 static int ltc4245_read_power(struct device *dev, u32 attr, int channel,
318 			      long *val)
319 {
320 	unsigned long curr;
321 	long voltage;
322 
323 	switch (attr) {
324 	case hwmon_power_input:
325 		(void)ltc4245_update_device(dev);
326 		curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
327 		voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]);
328 		*val = abs(curr * voltage);
329 		return 0;
330 	default:
331 		return -EOPNOTSUPP;
332 	}
333 }
334 
335 static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type,
336 			u32 attr, int channel, long *val)
337 {
338 
339 	switch (type) {
340 	case hwmon_curr:
341 		return ltc4245_read_curr(dev, attr, channel, val);
342 	case hwmon_power:
343 		return ltc4245_read_power(dev, attr, channel, val);
344 	case hwmon_in:
345 		return ltc4245_read_in(dev, attr, channel - 1, val);
346 	default:
347 		return -EOPNOTSUPP;
348 	}
349 }
350 
351 static umode_t ltc4245_is_visible(const void *_data,
352 				  enum hwmon_sensor_types type,
353 				  u32 attr, int channel)
354 {
355 	const struct ltc4245_data *data = _data;
356 
357 	switch (type) {
358 	case hwmon_in:
359 		if (channel == 0)
360 			return 0;
361 		switch (attr) {
362 		case hwmon_in_input:
363 			if (channel > 9 && !data->use_extra_gpios)
364 				return 0;
365 			return 0444;
366 		case hwmon_in_min_alarm:
367 			if (channel > 8)
368 				return 0;
369 			return 0444;
370 		default:
371 			return 0;
372 		}
373 	case hwmon_curr:
374 		switch (attr) {
375 		case hwmon_curr_input:
376 		case hwmon_curr_max_alarm:
377 			return 0444;
378 		default:
379 			return 0;
380 		}
381 	case hwmon_power:
382 		switch (attr) {
383 		case hwmon_power_input:
384 			return 0444;
385 		default:
386 			return 0;
387 		}
388 	default:
389 		return 0;
390 	}
391 }
392 
393 static const u32 ltc4245_in_config[] = {
394 	HWMON_I_INPUT,			/* dummy, skipped in is_visible */
395 	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
396 	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
397 	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
398 	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
399 	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
400 	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
401 	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
402 	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
403 	HWMON_I_INPUT,
404 	HWMON_I_INPUT,
405 	HWMON_I_INPUT,
406 	0
407 };
408 
409 static const struct hwmon_channel_info ltc4245_in = {
410 	.type = hwmon_in,
411 	.config = ltc4245_in_config,
412 };
413 
414 static const u32 ltc4245_curr_config[] = {
415 	HWMON_C_INPUT | HWMON_C_MAX_ALARM,
416 	HWMON_C_INPUT | HWMON_C_MAX_ALARM,
417 	HWMON_C_INPUT | HWMON_C_MAX_ALARM,
418 	HWMON_C_INPUT | HWMON_C_MAX_ALARM,
419 	0
420 };
421 
422 static const struct hwmon_channel_info ltc4245_curr = {
423 	.type = hwmon_curr,
424 	.config = ltc4245_curr_config,
425 };
426 
427 static const u32 ltc4245_power_config[] = {
428 	HWMON_P_INPUT,
429 	HWMON_P_INPUT,
430 	HWMON_P_INPUT,
431 	HWMON_P_INPUT,
432 	0
433 };
434 
435 static const struct hwmon_channel_info ltc4245_power = {
436 	.type = hwmon_power,
437 	.config = ltc4245_power_config,
438 };
439 
440 static const struct hwmon_channel_info *ltc4245_info[] = {
441 	&ltc4245_in,
442 	&ltc4245_curr,
443 	&ltc4245_power,
444 	NULL
445 };
446 
447 static const struct hwmon_ops ltc4245_hwmon_ops = {
448 	.is_visible = ltc4245_is_visible,
449 	.read = ltc4245_read,
450 };
451 
452 static const struct hwmon_chip_info ltc4245_chip_info = {
453 	.ops = &ltc4245_hwmon_ops,
454 	.info = ltc4245_info,
455 };
456 
457 static bool ltc4245_use_extra_gpios(struct i2c_client *client)
458 {
459 	struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
460 	struct device_node *np = client->dev.of_node;
461 
462 	/* prefer platform data */
463 	if (pdata)
464 		return pdata->use_extra_gpios;
465 
466 	/* fallback on OF */
467 	if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
468 		return true;
469 
470 	return false;
471 }
472 
473 static int ltc4245_probe(struct i2c_client *client,
474 			 const struct i2c_device_id *id)
475 {
476 	struct i2c_adapter *adapter = client->adapter;
477 	struct ltc4245_data *data;
478 	struct device *hwmon_dev;
479 
480 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
481 		return -ENODEV;
482 
483 	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
484 	if (!data)
485 		return -ENOMEM;
486 
487 	data->client = client;
488 	mutex_init(&data->update_lock);
489 	data->use_extra_gpios = ltc4245_use_extra_gpios(client);
490 
491 	/* Initialize the LTC4245 chip */
492 	i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
493 	i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
494 
495 	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
496 							 client->name, data,
497 							 &ltc4245_chip_info,
498 							 NULL);
499 	return PTR_ERR_OR_ZERO(hwmon_dev);
500 }
501 
502 static const struct i2c_device_id ltc4245_id[] = {
503 	{ "ltc4245", 0 },
504 	{ }
505 };
506 MODULE_DEVICE_TABLE(i2c, ltc4245_id);
507 
508 /* This is the driver that will be inserted */
509 static struct i2c_driver ltc4245_driver = {
510 	.driver = {
511 		.name	= "ltc4245",
512 	},
513 	.probe		= ltc4245_probe,
514 	.id_table	= ltc4245_id,
515 };
516 
517 module_i2c_driver(ltc4245_driver);
518 
519 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
520 MODULE_DESCRIPTION("LTC4245 driver");
521 MODULE_LICENSE("GPL");
522