summaryrefslogtreecommitdiffstats
path: root/drivers/hwmon/ltc4245.c
blob: 082f0a0bd8a0f127913f3076177b0a62c8a4fdf9 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
/*
 * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
 *
 * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * This driver is based on the ds1621 and ina209 drivers.
 *
 * Datasheet:
 * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/bitops.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/i2c.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/platform_data/ltc4245.h>

/* Here are names of the chip's registers (a.k.a. commands) */
enum ltc4245_cmd {
	LTC4245_STATUS			= 0x00, /* readonly */
	LTC4245_ALERT			= 0x01,
	LTC4245_CONTROL			= 0x02,
	LTC4245_ON			= 0x03,
	LTC4245_FAULT1			= 0x04,
	LTC4245_FAULT2			= 0x05,
	LTC4245_GPIO			= 0x06,
	LTC4245_ADCADR			= 0x07,

	LTC4245_12VIN			= 0x10,
	LTC4245_12VSENSE		= 0x11,
	LTC4245_12VOUT			= 0x12,
	LTC4245_5VIN			= 0x13,
	LTC4245_5VSENSE			= 0x14,
	LTC4245_5VOUT			= 0x15,
	LTC4245_3VIN			= 0x16,
	LTC4245_3VSENSE			= 0x17,
	LTC4245_3VOUT			= 0x18,
	LTC4245_VEEIN			= 0x19,
	LTC4245_VEESENSE		= 0x1a,
	LTC4245_VEEOUT			= 0x1b,
	LTC4245_GPIOADC			= 0x1c,
};

struct ltc4245_data {
	struct i2c_client *client;

	struct mutex update_lock;
	bool valid;
	unsigned long last_updated; /* in jiffies */

	/* Control registers */
	u8 cregs[0x08];

	/* Voltage registers */
	u8 vregs[0x0d];

	/* GPIO ADC registers */
	bool use_extra_gpios;
	int gpios[3];
};

/*
 * Update the readings from the GPIO pins. If the driver has been configured to
 * sample all GPIO's as analog voltages, a round-robin sampling method is used.
 * Otherwise, only the configured GPIO pin is sampled.
 *
 * LOCKING: must hold data->update_lock
 */
static void ltc4245_update_gpios(struct device *dev)
{
	struct ltc4245_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	u8 gpio_curr, gpio_next, gpio_reg;
	int i;

	/* no extra gpio support, we're basically done */
	if (!data->use_extra_gpios) {
		data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
		return;
	}

	/*
	 * If the last reading was too long ago, then we mark all old GPIO
	 * readings as stale by setting them to -EAGAIN
	 */
	if (time_after(jiffies, data->last_updated + 5 * HZ)) {
		for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
			data->gpios[i] = -EAGAIN;
	}

	/*
	 * Get the current GPIO pin
	 *
	 * The datasheet calls these GPIO[1-3], but we'll calculate the zero
	 * based array index instead, and call them GPIO[0-2]. This is much
	 * easier to think about.
	 */
	gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
	if (gpio_curr > 0)
		gpio_curr -= 1;

	/* Read the GPIO voltage from the GPIOADC register */
	data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];

	/* Find the next GPIO pin to read */
	gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);

	/*
	 * Calculate the correct setting for the GPIO register so it will
	 * sample the next GPIO pin
	 */
	gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);

	/* Update the GPIO register */
	i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);

	/* Update saved data */
	data->cregs[LTC4245_GPIO] = gpio_reg;
}

static struct ltc4245_data *ltc4245_update_device(struct device *dev)
{
	struct ltc4245_data *data = dev_get_drvdata(dev);
	struct i2c_client *client = data->client;
	s32 val;
	int i;

	mutex_lock(&data->update_lock);

	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {

		/* Read control registers -- 0x00 to 0x07 */
		for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
			val = i2c_smbus_read_byte_data(client, i);
			if (unlikely(val < 0))
				data->cregs[i] = 0;
			else
				data->cregs[i] = val;
		}

		/* Read voltage registers -- 0x10 to 0x1c */
		for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
			val = i2c_smbus_read_byte_data(client, i+0x10);
			if (unlikely(val < 0))
				data->vregs[i] = 0;
			else
				data->vregs[i] = val;
		}

		/* Update GPIO readings */
		ltc4245_update_gpios(dev);

		data->last_updated = jiffies;
		data->valid = true;
	}

	mutex_unlock(&data->update_lock);

	return data;
}

/* Return the voltage from the given register in millivolts */
static int ltc4245_get_voltage(struct device *dev, u8 reg)
{
	struct ltc4245_data *data = ltc4245_update_device(dev);
	const u8 regval = data->vregs[reg - 0x10];
	u32 voltage = 0;

	switch (reg) {
	case LTC4245_12VIN:
	case LTC4245_12VOUT:
		voltage = regval * 55;
		break;
	case LTC4245_5VIN:
	case LTC4245_5VOUT:
		voltage = regval * 22;
		break;
	case LTC4245_3VIN:
	case LTC4245_3VOUT:
		voltage = regval * 15;
		break;
	case LTC4245_VEEIN:
	case LTC4245_VEEOUT:
		voltage = regval * -55;
		break;
	case LTC4245_GPIOADC:
		voltage = regval * 10;
		break;
	default:
		/* If we get here, the developer messed up */
		WARN_ON_ONCE(1);
		break;
	}

	return voltage;
}

/* Return the current in the given sense register in milliAmperes */
static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
{
	struct ltc4245_data *data = ltc4245_update_device(dev);
	const u8 regval = data->vregs[reg - 0x10];
	unsigned int voltage;
	unsigned int curr;

	/*
	 * The strange looking conversions that follow are fixed-point
	 * math, since we cannot do floating point in the kernel.
	 *
	 * Step 1: convert sense register to microVolts
	 * Step 2: convert voltage to milliAmperes
	 *
	 * If you play around with the V=IR equation, you come up with
	 * the following: X uV / Y mOhm == Z mA
	 *
	 * With the resistors that are fractions of a milliOhm, we multiply
	 * the voltage and resistance by 10, to shift the decimal point.
	 * Now we can use the normal division operator again.
	 */

	switch (reg) {
	case LTC4245_12VSENSE:
		voltage = regval * 250; /* voltage in uV */
		curr = voltage / 50; /* sense resistor 50 mOhm */
		break;
	case LTC4245_5VSENSE:
		voltage = regval * 125; /* voltage in uV */
		curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
		break;
	case LTC4245_3VSENSE:
		voltage = regval * 125; /* voltage in uV */
		curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
		break;
	case LTC4245_VEESENSE:
		voltage = regval * 250; /* voltage in uV */
		curr = voltage / 100; /* sense resistor 100 mOhm */
		break;
	default:
		/* If we get here, the developer messed up */
		WARN_ON_ONCE(1);
		curr = 0;
		break;
	}

	return curr;
}

/* Map from voltage channel index to voltage register */

static const s8 ltc4245_in_regs[] = {
	LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN,
	LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT,
};

/* Map from current channel index to current register */

static const s8 ltc4245_curr_regs[] = {
	LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE,
};

static int ltc4245_read_curr(struct device *dev, u32 attr, int channel,
			     long *val)
{
	struct ltc4245_data *data = ltc4245_update_device(dev);

	switch (attr) {
	case hwmon_curr_input:
		*val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
		return 0;
	case hwmon_curr_max_alarm:
		*val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4));
		return 0;
	default:
		return -EOPNOTSUPP;
	}
}

static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val)
{
	struct ltc4245_data *data = ltc4245_update_device(dev);

	switch (attr) {
	case hwmon_in_input:
		if (channel < 8) {
			*val = ltc4245_get_voltage(dev,
						ltc4245_in_regs[channel]);
		} else {
			int regval = data->gpios[channel - 8];

			if (regval < 0)
				return regval;
			*val = regval * 10;
		}
		return 0;
	case hwmon_in_min_alarm:
		if (channel < 4)
			*val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel));
		else
			*val = !!(data->cregs[LTC4245_FAULT2] &
				  BIT(channel - 4));
		return 0;
	default:
		return -EOPNOTSUPP;
	}
}

static int ltc4245_read_power(struct device *dev, u32 attr, int channel,
			      long *val)
{
	unsigned long curr;
	long voltage;

	switch (attr) {
	case hwmon_power_input:
		(void)ltc4245_update_device(dev);
		curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
		voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]);
		*val = abs(curr * voltage);
		return 0;
	default:
		return -EOPNOTSUPP;
	}
}

static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type,
			u32 attr, int channel, long *val)
{

	switch (type) {
	case hwmon_curr:
		return ltc4245_read_curr(dev, attr, channel, val);
	case hwmon_power:
		return ltc4245_read_power(dev, attr, channel, val);
	case hwmon_in:
		return ltc4245_read_in(dev, attr, channel - 1, val);
	default:
		return -EOPNOTSUPP;
	}
}

static umode_t ltc4245_is_visible(const void *_data,
				  enum hwmon_sensor_types type,
				  u32 attr, int channel)
{
	const struct ltc4245_data *data = _data;

	switch (type) {
	case hwmon_in:
		if (channel == 0)
			return 0;
		switch (attr) {
		case hwmon_in_input:
			if (channel > 9 && !data->use_extra_gpios)
				return 0;
			return S_IRUGO;
		case hwmon_in_min_alarm:
			if (channel > 8)
				return 0;
			return S_IRUGO;
		default:
			return 0;
		}
	case hwmon_curr:
		switch (attr) {
		case hwmon_curr_input:
		case hwmon_curr_max_alarm:
			return S_IRUGO;
		default:
			return 0;
		}
	case hwmon_power:
		switch (attr) {
		case hwmon_power_input:
			return S_IRUGO;
		default:
			return 0;
		}
	default:
		return 0;
	}
}

static const u32 ltc4245_in_config[] = {
	HWMON_I_INPUT,			/* dummy, skipped in is_visible */
	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
	HWMON_I_INPUT | HWMON_I_MIN_ALARM,
	HWMON_I_INPUT,
	HWMON_I_INPUT,
	HWMON_I_INPUT,
	0
};

static const struct hwmon_channel_info ltc4245_in = {
	.type = hwmon_in,
	.config = ltc4245_in_config,
};

static const u32 ltc4245_curr_config[] = {
	HWMON_C_INPUT | HWMON_C_MAX_ALARM,
	HWMON_C_INPUT | HWMON_C_MAX_ALARM,
	HWMON_C_INPUT | HWMON_C_MAX_ALARM,
	HWMON_C_INPUT | HWMON_C_MAX_ALARM,
	0
};

static const struct hwmon_channel_info ltc4245_curr = {
	.type = hwmon_curr,
	.config = ltc4245_curr_config,
};

static const u32 ltc4245_power_config[] = {
	HWMON_P_INPUT,
	HWMON_P_INPUT,
	HWMON_P_INPUT,
	HWMON_P_INPUT,
	0
};

static const struct hwmon_channel_info ltc4245_power = {
	.type = hwmon_power,
	.config = ltc4245_power_config,
};

static const struct hwmon_channel_info *ltc4245_info[] = {
	&ltc4245_in,
	&ltc4245_curr,
	&ltc4245_power,
	NULL
};

static const struct hwmon_ops ltc4245_hwmon_ops = {
	.is_visible = ltc4245_is_visible,
	.read = ltc4245_read,
};

static const struct hwmon_chip_info ltc4245_chip_info = {
	.ops = &ltc4245_hwmon_ops,
	.info = ltc4245_info,
};

static bool ltc4245_use_extra_gpios(struct i2c_client *client)
{
	struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
	struct device_node *np = client->dev.of_node;

	/* prefer platform data */
	if (pdata)
		return pdata->use_extra_gpios;

	/* fallback on OF */
	if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
		return true;

	return false;
}

static int ltc4245_probe(struct i2c_client *client,
			 const struct i2c_device_id *id)
{
	struct i2c_adapter *adapter = client->adapter;
	struct ltc4245_data *data;
	struct device *hwmon_dev;

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
		return -ENODEV;

	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->client = client;
	mutex_init(&data->update_lock);
	data->use_extra_gpios = ltc4245_use_extra_gpios(client);

	/* Initialize the LTC4245 chip */
	i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
	i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);

	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
							 client->name, data,
							 &ltc4245_chip_info,
							 NULL);
	return PTR_ERR_OR_ZERO(hwmon_dev);
}

static const struct i2c_device_id ltc4245_id[] = {
	{ "ltc4245", 0 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, ltc4245_id);

/* This is the driver that will be inserted */
static struct i2c_driver ltc4245_driver = {
	.driver = {
		.name	= "ltc4245",
	},
	.probe		= ltc4245_probe,
	.id_table	= ltc4245_id,
};

module_i2c_driver(ltc4245_driver);

MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
MODULE_DESCRIPTION("LTC4245 driver");
MODULE_LICENSE("GPL");