xref: /openbmc/linux/drivers/hwmon/ltc4245.c (revision 1975d167)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Driver for Linear Technology LTC4245 I2C Multiple Supply Hot Swap Controller
4  *
5  * Copyright (C) 2008 Ira W. Snyder <iws@ovro.caltech.edu>
6  *
7  * This driver is based on the ds1621 and ina209 drivers.
8  *
9  * Datasheet:
10  * http://www.linear.com/pc/downloadDocument.do?navId=H0,C1,C1003,C1006,C1140,P19392,D13517
11  */
12 
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/init.h>
16 #include <linux/bitops.h>
17 #include <linux/err.h>
18 #include <linux/slab.h>
19 #include <linux/i2c.h>
20 #include <linux/hwmon.h>
21 #include <linux/hwmon-sysfs.h>
22 #include <linux/jiffies.h>
23 #include <linux/platform_data/ltc4245.h>
24 
25 /* Here are names of the chip's registers (a.k.a. commands) */
26 enum ltc4245_cmd {
27 	LTC4245_STATUS			= 0x00, /* readonly */
28 	LTC4245_ALERT			= 0x01,
29 	LTC4245_CONTROL			= 0x02,
30 	LTC4245_ON			= 0x03,
31 	LTC4245_FAULT1			= 0x04,
32 	LTC4245_FAULT2			= 0x05,
33 	LTC4245_GPIO			= 0x06,
34 	LTC4245_ADCADR			= 0x07,
35 
36 	LTC4245_12VIN			= 0x10,
37 	LTC4245_12VSENSE		= 0x11,
38 	LTC4245_12VOUT			= 0x12,
39 	LTC4245_5VIN			= 0x13,
40 	LTC4245_5VSENSE			= 0x14,
41 	LTC4245_5VOUT			= 0x15,
42 	LTC4245_3VIN			= 0x16,
43 	LTC4245_3VSENSE			= 0x17,
44 	LTC4245_3VOUT			= 0x18,
45 	LTC4245_VEEIN			= 0x19,
46 	LTC4245_VEESENSE		= 0x1a,
47 	LTC4245_VEEOUT			= 0x1b,
48 	LTC4245_GPIOADC			= 0x1c,
49 };
50 
51 struct ltc4245_data {
52 	struct i2c_client *client;
53 
54 	struct mutex update_lock;
55 	bool valid;
56 	unsigned long last_updated; /* in jiffies */
57 
58 	/* Control registers */
59 	u8 cregs[0x08];
60 
61 	/* Voltage registers */
62 	u8 vregs[0x0d];
63 
64 	/* GPIO ADC registers */
65 	bool use_extra_gpios;
66 	int gpios[3];
67 };
68 
69 /*
70  * Update the readings from the GPIO pins. If the driver has been configured to
71  * sample all GPIO's as analog voltages, a round-robin sampling method is used.
72  * Otherwise, only the configured GPIO pin is sampled.
73  *
74  * LOCKING: must hold data->update_lock
75  */
ltc4245_update_gpios(struct device * dev)76 static void ltc4245_update_gpios(struct device *dev)
77 {
78 	struct ltc4245_data *data = dev_get_drvdata(dev);
79 	struct i2c_client *client = data->client;
80 	u8 gpio_curr, gpio_next, gpio_reg;
81 	int i;
82 
83 	/* no extra gpio support, we're basically done */
84 	if (!data->use_extra_gpios) {
85 		data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
86 		return;
87 	}
88 
89 	/*
90 	 * If the last reading was too long ago, then we mark all old GPIO
91 	 * readings as stale by setting them to -EAGAIN
92 	 */
93 	if (time_after(jiffies, data->last_updated + 5 * HZ)) {
94 		for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
95 			data->gpios[i] = -EAGAIN;
96 	}
97 
98 	/*
99 	 * Get the current GPIO pin
100 	 *
101 	 * The datasheet calls these GPIO[1-3], but we'll calculate the zero
102 	 * based array index instead, and call them GPIO[0-2]. This is much
103 	 * easier to think about.
104 	 */
105 	gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
106 	if (gpio_curr > 0)
107 		gpio_curr -= 1;
108 
109 	/* Read the GPIO voltage from the GPIOADC register */
110 	data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];
111 
112 	/* Find the next GPIO pin to read */
113 	gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);
114 
115 	/*
116 	 * Calculate the correct setting for the GPIO register so it will
117 	 * sample the next GPIO pin
118 	 */
119 	gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);
120 
121 	/* Update the GPIO register */
122 	i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);
123 
124 	/* Update saved data */
125 	data->cregs[LTC4245_GPIO] = gpio_reg;
126 }
127 
ltc4245_update_device(struct device * dev)128 static struct ltc4245_data *ltc4245_update_device(struct device *dev)
129 {
130 	struct ltc4245_data *data = dev_get_drvdata(dev);
131 	struct i2c_client *client = data->client;
132 	s32 val;
133 	int i;
134 
135 	mutex_lock(&data->update_lock);
136 
137 	if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
138 
139 		/* Read control registers -- 0x00 to 0x07 */
140 		for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
141 			val = i2c_smbus_read_byte_data(client, i);
142 			if (unlikely(val < 0))
143 				data->cregs[i] = 0;
144 			else
145 				data->cregs[i] = val;
146 		}
147 
148 		/* Read voltage registers -- 0x10 to 0x1c */
149 		for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
150 			val = i2c_smbus_read_byte_data(client, i+0x10);
151 			if (unlikely(val < 0))
152 				data->vregs[i] = 0;
153 			else
154 				data->vregs[i] = val;
155 		}
156 
157 		/* Update GPIO readings */
158 		ltc4245_update_gpios(dev);
159 
160 		data->last_updated = jiffies;
161 		data->valid = true;
162 	}
163 
164 	mutex_unlock(&data->update_lock);
165 
166 	return data;
167 }
168 
169 /* Return the voltage from the given register in millivolts */
ltc4245_get_voltage(struct device * dev,u8 reg)170 static int ltc4245_get_voltage(struct device *dev, u8 reg)
171 {
172 	struct ltc4245_data *data = ltc4245_update_device(dev);
173 	const u8 regval = data->vregs[reg - 0x10];
174 	u32 voltage = 0;
175 
176 	switch (reg) {
177 	case LTC4245_12VIN:
178 	case LTC4245_12VOUT:
179 		voltage = regval * 55;
180 		break;
181 	case LTC4245_5VIN:
182 	case LTC4245_5VOUT:
183 		voltage = regval * 22;
184 		break;
185 	case LTC4245_3VIN:
186 	case LTC4245_3VOUT:
187 		voltage = regval * 15;
188 		break;
189 	case LTC4245_VEEIN:
190 	case LTC4245_VEEOUT:
191 		voltage = regval * -55;
192 		break;
193 	case LTC4245_GPIOADC:
194 		voltage = regval * 10;
195 		break;
196 	default:
197 		/* If we get here, the developer messed up */
198 		WARN_ON_ONCE(1);
199 		break;
200 	}
201 
202 	return voltage;
203 }
204 
205 /* Return the current in the given sense register in milliAmperes */
ltc4245_get_current(struct device * dev,u8 reg)206 static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
207 {
208 	struct ltc4245_data *data = ltc4245_update_device(dev);
209 	const u8 regval = data->vregs[reg - 0x10];
210 	unsigned int voltage;
211 	unsigned int curr;
212 
213 	/*
214 	 * The strange looking conversions that follow are fixed-point
215 	 * math, since we cannot do floating point in the kernel.
216 	 *
217 	 * Step 1: convert sense register to microVolts
218 	 * Step 2: convert voltage to milliAmperes
219 	 *
220 	 * If you play around with the V=IR equation, you come up with
221 	 * the following: X uV / Y mOhm == Z mA
222 	 *
223 	 * With the resistors that are fractions of a milliOhm, we multiply
224 	 * the voltage and resistance by 10, to shift the decimal point.
225 	 * Now we can use the normal division operator again.
226 	 */
227 
228 	switch (reg) {
229 	case LTC4245_12VSENSE:
230 		voltage = regval * 250; /* voltage in uV */
231 		curr = voltage / 50; /* sense resistor 50 mOhm */
232 		break;
233 	case LTC4245_5VSENSE:
234 		voltage = regval * 125; /* voltage in uV */
235 		curr = (voltage * 10) / 35; /* sense resistor 3.5 mOhm */
236 		break;
237 	case LTC4245_3VSENSE:
238 		voltage = regval * 125; /* voltage in uV */
239 		curr = (voltage * 10) / 25; /* sense resistor 2.5 mOhm */
240 		break;
241 	case LTC4245_VEESENSE:
242 		voltage = regval * 250; /* voltage in uV */
243 		curr = voltage / 100; /* sense resistor 100 mOhm */
244 		break;
245 	default:
246 		/* If we get here, the developer messed up */
247 		WARN_ON_ONCE(1);
248 		curr = 0;
249 		break;
250 	}
251 
252 	return curr;
253 }
254 
255 /* Map from voltage channel index to voltage register */
256 
257 static const s8 ltc4245_in_regs[] = {
258 	LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN,
259 	LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT,
260 };
261 
262 /* Map from current channel index to current register */
263 
264 static const s8 ltc4245_curr_regs[] = {
265 	LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE,
266 };
267 
ltc4245_read_curr(struct device * dev,u32 attr,int channel,long * val)268 static int ltc4245_read_curr(struct device *dev, u32 attr, int channel,
269 			     long *val)
270 {
271 	struct ltc4245_data *data = ltc4245_update_device(dev);
272 
273 	switch (attr) {
274 	case hwmon_curr_input:
275 		*val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
276 		return 0;
277 	case hwmon_curr_max_alarm:
278 		*val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4));
279 		return 0;
280 	default:
281 		return -EOPNOTSUPP;
282 	}
283 }
284 
ltc4245_read_in(struct device * dev,u32 attr,int channel,long * val)285 static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val)
286 {
287 	struct ltc4245_data *data = ltc4245_update_device(dev);
288 
289 	switch (attr) {
290 	case hwmon_in_input:
291 		if (channel < 8) {
292 			*val = ltc4245_get_voltage(dev,
293 						ltc4245_in_regs[channel]);
294 		} else {
295 			int regval = data->gpios[channel - 8];
296 
297 			if (regval < 0)
298 				return regval;
299 			*val = regval * 10;
300 		}
301 		return 0;
302 	case hwmon_in_min_alarm:
303 		if (channel < 4)
304 			*val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel));
305 		else
306 			*val = !!(data->cregs[LTC4245_FAULT2] &
307 				  BIT(channel - 4));
308 		return 0;
309 	default:
310 		return -EOPNOTSUPP;
311 	}
312 }
313 
ltc4245_read_power(struct device * dev,u32 attr,int channel,long * val)314 static int ltc4245_read_power(struct device *dev, u32 attr, int channel,
315 			      long *val)
316 {
317 	unsigned long curr;
318 	long voltage;
319 
320 	switch (attr) {
321 	case hwmon_power_input:
322 		(void)ltc4245_update_device(dev);
323 		curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
324 		voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]);
325 		*val = abs(curr * voltage);
326 		return 0;
327 	default:
328 		return -EOPNOTSUPP;
329 	}
330 }
331 
ltc4245_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * val)332 static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type,
333 			u32 attr, int channel, long *val)
334 {
335 
336 	switch (type) {
337 	case hwmon_curr:
338 		return ltc4245_read_curr(dev, attr, channel, val);
339 	case hwmon_power:
340 		return ltc4245_read_power(dev, attr, channel, val);
341 	case hwmon_in:
342 		return ltc4245_read_in(dev, attr, channel - 1, val);
343 	default:
344 		return -EOPNOTSUPP;
345 	}
346 }
347 
ltc4245_is_visible(const void * _data,enum hwmon_sensor_types type,u32 attr,int channel)348 static umode_t ltc4245_is_visible(const void *_data,
349 				  enum hwmon_sensor_types type,
350 				  u32 attr, int channel)
351 {
352 	const struct ltc4245_data *data = _data;
353 
354 	switch (type) {
355 	case hwmon_in:
356 		if (channel == 0)
357 			return 0;
358 		switch (attr) {
359 		case hwmon_in_input:
360 			if (channel > 9 && !data->use_extra_gpios)
361 				return 0;
362 			return 0444;
363 		case hwmon_in_min_alarm:
364 			if (channel > 8)
365 				return 0;
366 			return 0444;
367 		default:
368 			return 0;
369 		}
370 	case hwmon_curr:
371 		switch (attr) {
372 		case hwmon_curr_input:
373 		case hwmon_curr_max_alarm:
374 			return 0444;
375 		default:
376 			return 0;
377 		}
378 	case hwmon_power:
379 		switch (attr) {
380 		case hwmon_power_input:
381 			return 0444;
382 		default:
383 			return 0;
384 		}
385 	default:
386 		return 0;
387 	}
388 }
389 
390 static const struct hwmon_channel_info * const ltc4245_info[] = {
391 	HWMON_CHANNEL_INFO(in,
392 			   HWMON_I_INPUT,
393 			   HWMON_I_INPUT | HWMON_I_MIN_ALARM,
394 			   HWMON_I_INPUT | HWMON_I_MIN_ALARM,
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,
402 			   HWMON_I_INPUT,
403 			   HWMON_I_INPUT),
404 	HWMON_CHANNEL_INFO(curr,
405 			   HWMON_C_INPUT | HWMON_C_MAX_ALARM,
406 			   HWMON_C_INPUT | HWMON_C_MAX_ALARM,
407 			   HWMON_C_INPUT | HWMON_C_MAX_ALARM,
408 			   HWMON_C_INPUT | HWMON_C_MAX_ALARM),
409 	HWMON_CHANNEL_INFO(power,
410 			   HWMON_P_INPUT,
411 			   HWMON_P_INPUT,
412 			   HWMON_P_INPUT,
413 			   HWMON_P_INPUT),
414 	NULL
415 };
416 
417 static const struct hwmon_ops ltc4245_hwmon_ops = {
418 	.is_visible = ltc4245_is_visible,
419 	.read = ltc4245_read,
420 };
421 
422 static const struct hwmon_chip_info ltc4245_chip_info = {
423 	.ops = &ltc4245_hwmon_ops,
424 	.info = ltc4245_info,
425 };
426 
ltc4245_use_extra_gpios(struct i2c_client * client)427 static bool ltc4245_use_extra_gpios(struct i2c_client *client)
428 {
429 	struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
430 	struct device_node *np = client->dev.of_node;
431 
432 	/* prefer platform data */
433 	if (pdata)
434 		return pdata->use_extra_gpios;
435 
436 	/* fallback on OF */
437 	if (of_property_read_bool(np, "ltc4245,use-extra-gpios"))
438 		return true;
439 
440 	return false;
441 }
442 
ltc4245_probe(struct i2c_client * client)443 static int ltc4245_probe(struct i2c_client *client)
444 {
445 	struct i2c_adapter *adapter = client->adapter;
446 	struct ltc4245_data *data;
447 	struct device *hwmon_dev;
448 
449 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
450 		return -ENODEV;
451 
452 	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
453 	if (!data)
454 		return -ENOMEM;
455 
456 	data->client = client;
457 	mutex_init(&data->update_lock);
458 	data->use_extra_gpios = ltc4245_use_extra_gpios(client);
459 
460 	/* Initialize the LTC4245 chip */
461 	i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
462 	i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
463 
464 	hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
465 							 client->name, data,
466 							 &ltc4245_chip_info,
467 							 NULL);
468 	return PTR_ERR_OR_ZERO(hwmon_dev);
469 }
470 
471 static const struct i2c_device_id ltc4245_id[] = {
472 	{ "ltc4245", 0 },
473 	{ }
474 };
475 MODULE_DEVICE_TABLE(i2c, ltc4245_id);
476 
477 /* This is the driver that will be inserted */
478 static struct i2c_driver ltc4245_driver = {
479 	.driver = {
480 		.name	= "ltc4245",
481 	},
482 	.probe		= ltc4245_probe,
483 	.id_table	= ltc4245_id,
484 };
485 
486 module_i2c_driver(ltc4245_driver);
487 
488 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
489 MODULE_DESCRIPTION("LTC4245 driver");
490 MODULE_LICENSE("GPL");
491