xref: /openbmc/linux/drivers/hwmon/ina209.c (revision f35e839a)
1 /*
2  * Driver for the Texas Instruments / Burr Brown INA209
3  * Bidirectional Current/Power Monitor
4  *
5  * Copyright (C) 2012 Guenter Roeck <linux@roeck-us.net>
6  *
7  * Derived from Ira W. Snyder's original driver submission
8  *	Copyright (C) 2008 Paul Hays <Paul.Hays@cattail.ca>
9  *	Copyright (C) 2008-2009 Ira W. Snyder <iws@ovro.caltech.edu>
10  *
11  * Aligned with ina2xx driver
12  *	Copyright (C) 2012 Lothar Felten <l-felten@ti.com>
13  *	Thanks to Jan Volkering
14  *
15  * This program is free software; you can redistribute it and/or modify
16  * it under the terms of the GNU General Public License as published by
17  * the Free Software Foundation; version 2 of the License.
18  *
19  * Datasheet:
20  * http://www.ti.com/lit/gpn/ina209
21  */
22 
23 #include <linux/kernel.h>
24 #include <linux/module.h>
25 #include <linux/init.h>
26 #include <linux/err.h>
27 #include <linux/slab.h>
28 #include <linux/bug.h>
29 #include <linux/i2c.h>
30 #include <linux/hwmon.h>
31 #include <linux/hwmon-sysfs.h>
32 
33 #include <linux/platform_data/ina2xx.h>
34 
35 /* register definitions */
36 #define INA209_CONFIGURATION		0x00
37 #define INA209_STATUS			0x01
38 #define INA209_STATUS_MASK		0x02
39 #define INA209_SHUNT_VOLTAGE		0x03
40 #define INA209_BUS_VOLTAGE		0x04
41 #define INA209_POWER			0x05
42 #define INA209_CURRENT			0x06
43 #define INA209_SHUNT_VOLTAGE_POS_PEAK	0x07
44 #define INA209_SHUNT_VOLTAGE_NEG_PEAK	0x08
45 #define INA209_BUS_VOLTAGE_MAX_PEAK	0x09
46 #define INA209_BUS_VOLTAGE_MIN_PEAK	0x0a
47 #define INA209_POWER_PEAK		0x0b
48 #define INA209_SHUNT_VOLTAGE_POS_WARN	0x0c
49 #define INA209_SHUNT_VOLTAGE_NEG_WARN	0x0d
50 #define INA209_POWER_WARN		0x0e
51 #define INA209_BUS_VOLTAGE_OVER_WARN	0x0f
52 #define INA209_BUS_VOLTAGE_UNDER_WARN	0x10
53 #define INA209_POWER_OVER_LIMIT		0x11
54 #define INA209_BUS_VOLTAGE_OVER_LIMIT	0x12
55 #define INA209_BUS_VOLTAGE_UNDER_LIMIT	0x13
56 #define INA209_CRITICAL_DAC_POS		0x14
57 #define INA209_CRITICAL_DAC_NEG		0x15
58 #define INA209_CALIBRATION		0x16
59 
60 #define INA209_REGISTERS		0x17
61 
62 #define INA209_CONFIG_DEFAULT		0x3c47	/* PGA=8, full range */
63 #define INA209_SHUNT_DEFAULT		10000	/* uOhm */
64 
65 struct ina209_data {
66 	struct device *hwmon_dev;
67 
68 	struct mutex update_lock;
69 	bool valid;
70 	unsigned long last_updated;	/* in jiffies */
71 
72 	u16 regs[INA209_REGISTERS];	/* All chip registers */
73 
74 	u16 config_orig;		/* Original configuration */
75 	u16 calibration_orig;		/* Original calibration */
76 	u16 update_interval;
77 };
78 
79 static struct ina209_data *ina209_update_device(struct device *dev)
80 {
81 	struct i2c_client *client = to_i2c_client(dev);
82 	struct ina209_data *data = i2c_get_clientdata(client);
83 	struct ina209_data *ret = data;
84 	s32 val;
85 	int i;
86 
87 	mutex_lock(&data->update_lock);
88 
89 	if (!data->valid ||
90 	    time_after(jiffies, data->last_updated + data->update_interval)) {
91 		for (i = 0; i < ARRAY_SIZE(data->regs); i++) {
92 			val = i2c_smbus_read_word_swapped(client, i);
93 			if (val < 0) {
94 				ret = ERR_PTR(val);
95 				goto abort;
96 			}
97 			data->regs[i] = val;
98 		}
99 		data->last_updated = jiffies;
100 		data->valid = true;
101 	}
102 abort:
103 	mutex_unlock(&data->update_lock);
104 	return ret;
105 }
106 
107 /*
108  * Read a value from a device register and convert it to the
109  * appropriate sysfs units
110  */
111 static long ina209_from_reg(const u8 reg, const u16 val)
112 {
113 	switch (reg) {
114 	case INA209_SHUNT_VOLTAGE:
115 	case INA209_SHUNT_VOLTAGE_POS_PEAK:
116 	case INA209_SHUNT_VOLTAGE_NEG_PEAK:
117 	case INA209_SHUNT_VOLTAGE_POS_WARN:
118 	case INA209_SHUNT_VOLTAGE_NEG_WARN:
119 		/* LSB=10 uV. Convert to mV. */
120 		return DIV_ROUND_CLOSEST(val, 100);
121 
122 	case INA209_BUS_VOLTAGE:
123 	case INA209_BUS_VOLTAGE_MAX_PEAK:
124 	case INA209_BUS_VOLTAGE_MIN_PEAK:
125 	case INA209_BUS_VOLTAGE_OVER_WARN:
126 	case INA209_BUS_VOLTAGE_UNDER_WARN:
127 	case INA209_BUS_VOLTAGE_OVER_LIMIT:
128 	case INA209_BUS_VOLTAGE_UNDER_LIMIT:
129 		/* LSB=4 mV, last 3 bits unused */
130 		return (val >> 3) * 4;
131 
132 	case INA209_CRITICAL_DAC_POS:
133 		/* LSB=1 mV, in the upper 8 bits */
134 		return val >> 8;
135 
136 	case INA209_CRITICAL_DAC_NEG:
137 		/* LSB=1 mV, in the upper 8 bits */
138 		return -1 * (val >> 8);
139 
140 	case INA209_POWER:
141 	case INA209_POWER_PEAK:
142 	case INA209_POWER_WARN:
143 	case INA209_POWER_OVER_LIMIT:
144 		/* LSB=20 mW. Convert to uW */
145 		return val * 20 * 1000L;
146 
147 	case INA209_CURRENT:
148 		/* LSB=1 mA (selected). Is in mA */
149 		return val;
150 	}
151 
152 	/* programmer goofed */
153 	WARN_ON_ONCE(1);
154 	return 0;
155 }
156 
157 /*
158  * Take a value and convert it to register format, clamping the value
159  * to the appropriate range.
160  */
161 static int ina209_to_reg(u8 reg, u16 old, long val)
162 {
163 	switch (reg) {
164 	case INA209_SHUNT_VOLTAGE_POS_WARN:
165 	case INA209_SHUNT_VOLTAGE_NEG_WARN:
166 		/* Limit to +- 320 mV, 10 uV LSB */
167 		return clamp_val(val, -320, 320) * 100;
168 
169 	case INA209_BUS_VOLTAGE_OVER_WARN:
170 	case INA209_BUS_VOLTAGE_UNDER_WARN:
171 	case INA209_BUS_VOLTAGE_OVER_LIMIT:
172 	case INA209_BUS_VOLTAGE_UNDER_LIMIT:
173 		/*
174 		 * Limit to 0-32000 mV, 4 mV LSB
175 		 *
176 		 * The last three bits aren't part of the value, but we'll
177 		 * preserve them in their original state.
178 		 */
179 		return (DIV_ROUND_CLOSEST(clamp_val(val, 0, 32000), 4) << 3)
180 		  | (old & 0x7);
181 
182 	case INA209_CRITICAL_DAC_NEG:
183 		/*
184 		 * Limit to -255-0 mV, 1 mV LSB
185 		 * Convert the value to a positive value for the register
186 		 *
187 		 * The value lives in the top 8 bits only, be careful
188 		 * and keep original value of other bits.
189 		 */
190 		return (clamp_val(-val, 0, 255) << 8) | (old & 0xff);
191 
192 	case INA209_CRITICAL_DAC_POS:
193 		/*
194 		 * Limit to 0-255 mV, 1 mV LSB
195 		 *
196 		 * The value lives in the top 8 bits only, be careful
197 		 * and keep original value of other bits.
198 		 */
199 		return (clamp_val(val, 0, 255) << 8) | (old & 0xff);
200 
201 	case INA209_POWER_WARN:
202 	case INA209_POWER_OVER_LIMIT:
203 		/* 20 mW LSB */
204 		return DIV_ROUND_CLOSEST(val, 20 * 1000);
205 	}
206 
207 	/* Other registers are read-only, return access error */
208 	return -EACCES;
209 }
210 
211 static int ina209_interval_from_reg(u16 reg)
212 {
213 	return 68 >> (15 - ((reg >> 3) & 0x0f));
214 }
215 
216 static u16 ina209_reg_from_interval(u16 config, long interval)
217 {
218 	int i, adc;
219 
220 	if (interval <= 0) {
221 		adc = 8;
222 	} else {
223 		adc = 15;
224 		for (i = 34 + 34 / 2; i; i >>= 1) {
225 			if (i < interval)
226 				break;
227 			adc--;
228 		}
229 	}
230 	return (config & 0xf807) | (adc << 3) | (adc << 7);
231 }
232 
233 static ssize_t ina209_set_interval(struct device *dev,
234 				   struct device_attribute *da,
235 				   const char *buf, size_t count)
236 {
237 	struct i2c_client *client = to_i2c_client(dev);
238 	struct ina209_data *data = ina209_update_device(dev);
239 	long val;
240 	u16 regval;
241 	int ret;
242 
243 	if (IS_ERR(data))
244 		return PTR_ERR(data);
245 
246 	ret = kstrtol(buf, 10, &val);
247 	if (ret < 0)
248 		return ret;
249 
250 	mutex_lock(&data->update_lock);
251 	regval = ina209_reg_from_interval(data->regs[INA209_CONFIGURATION],
252 					  val);
253 	i2c_smbus_write_word_swapped(client, INA209_CONFIGURATION, regval);
254 	data->regs[INA209_CONFIGURATION] = regval;
255 	data->update_interval = ina209_interval_from_reg(regval);
256 	mutex_unlock(&data->update_lock);
257 	return count;
258 }
259 
260 static ssize_t ina209_show_interval(struct device *dev,
261 				    struct device_attribute *da, char *buf)
262 {
263 	struct i2c_client *client = to_i2c_client(dev);
264 	struct ina209_data *data = i2c_get_clientdata(client);
265 
266 	return snprintf(buf, PAGE_SIZE, "%d\n", data->update_interval);
267 }
268 
269 /*
270  * History is reset by writing 1 into bit 0 of the respective peak register.
271  * Since more than one peak register may be affected by the scope of a
272  * reset_history attribute write, use a bit mask in attr->index to identify
273  * which registers are affected.
274  */
275 static u16 ina209_reset_history_regs[] = {
276 	INA209_SHUNT_VOLTAGE_POS_PEAK,
277 	INA209_SHUNT_VOLTAGE_NEG_PEAK,
278 	INA209_BUS_VOLTAGE_MAX_PEAK,
279 	INA209_BUS_VOLTAGE_MIN_PEAK,
280 	INA209_POWER_PEAK
281 };
282 
283 static ssize_t ina209_reset_history(struct device *dev,
284 				    struct device_attribute *da,
285 				    const char *buf,
286 				    size_t count)
287 {
288 	struct i2c_client *client = to_i2c_client(dev);
289 	struct ina209_data *data = i2c_get_clientdata(client);
290 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
291 	u32 mask = attr->index;
292 	long val;
293 	int i, ret;
294 
295 	ret = kstrtol(buf, 10, &val);
296 	if (ret < 0)
297 		return ret;
298 
299 	mutex_lock(&data->update_lock);
300 	for (i = 0; i < ARRAY_SIZE(ina209_reset_history_regs); i++) {
301 		if (mask & (1 << i))
302 			i2c_smbus_write_word_swapped(client,
303 					ina209_reset_history_regs[i], 1);
304 	}
305 	data->valid = false;
306 	mutex_unlock(&data->update_lock);
307 	return count;
308 }
309 
310 static ssize_t ina209_set_value(struct device *dev,
311 				struct device_attribute *da,
312 				const char *buf,
313 				size_t count)
314 {
315 	struct i2c_client *client = to_i2c_client(dev);
316 	struct ina209_data *data = ina209_update_device(dev);
317 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
318 	int reg = attr->index;
319 	long val;
320 	int ret;
321 
322 	if (IS_ERR(data))
323 		return PTR_ERR(data);
324 
325 	ret = kstrtol(buf, 10, &val);
326 	if (ret < 0)
327 		return ret;
328 
329 	mutex_lock(&data->update_lock);
330 	ret = ina209_to_reg(reg, data->regs[reg], val);
331 	if (ret < 0) {
332 		count = ret;
333 		goto abort;
334 	}
335 	i2c_smbus_write_word_swapped(client, reg, ret);
336 	data->regs[reg] = ret;
337 abort:
338 	mutex_unlock(&data->update_lock);
339 	return count;
340 }
341 
342 static ssize_t ina209_show_value(struct device *dev,
343 				 struct device_attribute *da,
344 				 char *buf)
345 {
346 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
347 	struct ina209_data *data = ina209_update_device(dev);
348 	long val;
349 
350 	if (IS_ERR(data))
351 		return PTR_ERR(data);
352 
353 	val = ina209_from_reg(attr->index, data->regs[attr->index]);
354 	return snprintf(buf, PAGE_SIZE, "%ld\n", val);
355 }
356 
357 static ssize_t ina209_show_alarm(struct device *dev,
358 				 struct device_attribute *da,
359 				 char *buf)
360 {
361 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
362 	struct ina209_data *data = ina209_update_device(dev);
363 	const unsigned int mask = attr->index;
364 	u16 status;
365 
366 	if (IS_ERR(data))
367 		return PTR_ERR(data);
368 
369 	status = data->regs[INA209_STATUS];
370 
371 	/*
372 	 * All alarms are in the INA209_STATUS register. To avoid a long
373 	 * switch statement, the mask is passed in attr->index
374 	 */
375 	return snprintf(buf, PAGE_SIZE, "%u\n", !!(status & mask));
376 }
377 
378 /* Shunt voltage, history, limits, alarms */
379 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina209_show_value, NULL,
380 			  INA209_SHUNT_VOLTAGE);
381 static SENSOR_DEVICE_ATTR(in0_input_highest, S_IRUGO, ina209_show_value, NULL,
382 			  INA209_SHUNT_VOLTAGE_POS_PEAK);
383 static SENSOR_DEVICE_ATTR(in0_input_lowest, S_IRUGO, ina209_show_value, NULL,
384 			  INA209_SHUNT_VOLTAGE_NEG_PEAK);
385 static SENSOR_DEVICE_ATTR(in0_reset_history, S_IWUSR, NULL,
386 			  ina209_reset_history, (1 << 0) | (1 << 1));
387 static SENSOR_DEVICE_ATTR(in0_max, S_IRUGO | S_IWUSR, ina209_show_value,
388 			  ina209_set_value, INA209_SHUNT_VOLTAGE_POS_WARN);
389 static SENSOR_DEVICE_ATTR(in0_min, S_IRUGO | S_IWUSR, ina209_show_value,
390 			  ina209_set_value, INA209_SHUNT_VOLTAGE_NEG_WARN);
391 static SENSOR_DEVICE_ATTR(in0_crit_max, S_IRUGO | S_IWUSR, ina209_show_value,
392 			  ina209_set_value, INA209_CRITICAL_DAC_POS);
393 static SENSOR_DEVICE_ATTR(in0_crit_min, S_IRUGO | S_IWUSR, ina209_show_value,
394 			  ina209_set_value, INA209_CRITICAL_DAC_NEG);
395 
396 static SENSOR_DEVICE_ATTR(in0_min_alarm,  S_IRUGO, ina209_show_alarm, NULL,
397 			  1 << 11);
398 static SENSOR_DEVICE_ATTR(in0_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
399 			  1 << 12);
400 static SENSOR_DEVICE_ATTR(in0_crit_min_alarm, S_IRUGO, ina209_show_alarm, NULL,
401 			  1 << 6);
402 static SENSOR_DEVICE_ATTR(in0_crit_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
403 			  1 << 7);
404 
405 /* Bus voltage, history, limits, alarms */
406 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ina209_show_value, NULL,
407 			  INA209_BUS_VOLTAGE);
408 static SENSOR_DEVICE_ATTR(in1_input_highest, S_IRUGO, ina209_show_value, NULL,
409 			  INA209_BUS_VOLTAGE_MAX_PEAK);
410 static SENSOR_DEVICE_ATTR(in1_input_lowest, S_IRUGO, ina209_show_value, NULL,
411 			  INA209_BUS_VOLTAGE_MIN_PEAK);
412 static SENSOR_DEVICE_ATTR(in1_reset_history, S_IWUSR, NULL,
413 			  ina209_reset_history, (1 << 2) | (1 << 3));
414 static SENSOR_DEVICE_ATTR(in1_max, S_IRUGO | S_IWUSR, ina209_show_value,
415 			  ina209_set_value, INA209_BUS_VOLTAGE_OVER_WARN);
416 static SENSOR_DEVICE_ATTR(in1_min, S_IRUGO | S_IWUSR, ina209_show_value,
417 			  ina209_set_value, INA209_BUS_VOLTAGE_UNDER_WARN);
418 static SENSOR_DEVICE_ATTR(in1_crit_max, S_IRUGO | S_IWUSR, ina209_show_value,
419 			  ina209_set_value, INA209_BUS_VOLTAGE_OVER_LIMIT);
420 static SENSOR_DEVICE_ATTR(in1_crit_min, S_IRUGO | S_IWUSR, ina209_show_value,
421 			  ina209_set_value, INA209_BUS_VOLTAGE_UNDER_LIMIT);
422 
423 static SENSOR_DEVICE_ATTR(in1_min_alarm, S_IRUGO, ina209_show_alarm, NULL,
424 			  1 << 14);
425 static SENSOR_DEVICE_ATTR(in1_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
426 			  1 << 15);
427 static SENSOR_DEVICE_ATTR(in1_crit_min_alarm, S_IRUGO, ina209_show_alarm, NULL,
428 			  1 << 9);
429 static SENSOR_DEVICE_ATTR(in1_crit_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
430 			  1 << 10);
431 
432 /* Power */
433 static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina209_show_value, NULL,
434 			  INA209_POWER);
435 static SENSOR_DEVICE_ATTR(power1_input_highest, S_IRUGO, ina209_show_value,
436 			  NULL, INA209_POWER_PEAK);
437 static SENSOR_DEVICE_ATTR(power1_reset_history, S_IWUSR, NULL,
438 			  ina209_reset_history, 1 << 4);
439 static SENSOR_DEVICE_ATTR(power1_max, S_IRUGO | S_IWUSR, ina209_show_value,
440 			  ina209_set_value, INA209_POWER_WARN);
441 static SENSOR_DEVICE_ATTR(power1_crit, S_IRUGO | S_IWUSR, ina209_show_value,
442 			  ina209_set_value, INA209_POWER_OVER_LIMIT);
443 
444 static SENSOR_DEVICE_ATTR(power1_max_alarm, S_IRUGO, ina209_show_alarm, NULL,
445 			  1 << 13);
446 static SENSOR_DEVICE_ATTR(power1_crit_alarm, S_IRUGO, ina209_show_alarm, NULL,
447 			  1 << 8);
448 
449 /* Current */
450 static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ina209_show_value, NULL,
451 			  INA209_CURRENT);
452 
453 static SENSOR_DEVICE_ATTR(update_interval, S_IRUGO | S_IWUSR,
454 			  ina209_show_interval, ina209_set_interval, 0);
455 
456 /*
457  * Finally, construct an array of pointers to members of the above objects,
458  * as required for sysfs_create_group()
459  */
460 static struct attribute *ina209_attributes[] = {
461 	&sensor_dev_attr_in0_input.dev_attr.attr,
462 	&sensor_dev_attr_in0_input_highest.dev_attr.attr,
463 	&sensor_dev_attr_in0_input_lowest.dev_attr.attr,
464 	&sensor_dev_attr_in0_reset_history.dev_attr.attr,
465 	&sensor_dev_attr_in0_max.dev_attr.attr,
466 	&sensor_dev_attr_in0_min.dev_attr.attr,
467 	&sensor_dev_attr_in0_crit_max.dev_attr.attr,
468 	&sensor_dev_attr_in0_crit_min.dev_attr.attr,
469 	&sensor_dev_attr_in0_max_alarm.dev_attr.attr,
470 	&sensor_dev_attr_in0_min_alarm.dev_attr.attr,
471 	&sensor_dev_attr_in0_crit_max_alarm.dev_attr.attr,
472 	&sensor_dev_attr_in0_crit_min_alarm.dev_attr.attr,
473 
474 	&sensor_dev_attr_in1_input.dev_attr.attr,
475 	&sensor_dev_attr_in1_input_highest.dev_attr.attr,
476 	&sensor_dev_attr_in1_input_lowest.dev_attr.attr,
477 	&sensor_dev_attr_in1_reset_history.dev_attr.attr,
478 	&sensor_dev_attr_in1_max.dev_attr.attr,
479 	&sensor_dev_attr_in1_min.dev_attr.attr,
480 	&sensor_dev_attr_in1_crit_max.dev_attr.attr,
481 	&sensor_dev_attr_in1_crit_min.dev_attr.attr,
482 	&sensor_dev_attr_in1_max_alarm.dev_attr.attr,
483 	&sensor_dev_attr_in1_min_alarm.dev_attr.attr,
484 	&sensor_dev_attr_in1_crit_max_alarm.dev_attr.attr,
485 	&sensor_dev_attr_in1_crit_min_alarm.dev_attr.attr,
486 
487 	&sensor_dev_attr_power1_input.dev_attr.attr,
488 	&sensor_dev_attr_power1_input_highest.dev_attr.attr,
489 	&sensor_dev_attr_power1_reset_history.dev_attr.attr,
490 	&sensor_dev_attr_power1_max.dev_attr.attr,
491 	&sensor_dev_attr_power1_crit.dev_attr.attr,
492 	&sensor_dev_attr_power1_max_alarm.dev_attr.attr,
493 	&sensor_dev_attr_power1_crit_alarm.dev_attr.attr,
494 
495 	&sensor_dev_attr_curr1_input.dev_attr.attr,
496 
497 	&sensor_dev_attr_update_interval.dev_attr.attr,
498 
499 	NULL,
500 };
501 
502 static const struct attribute_group ina209_group = {
503 	.attrs = ina209_attributes,
504 };
505 
506 static void ina209_restore_conf(struct i2c_client *client,
507 				struct ina209_data *data)
508 {
509 	/* Restore initial configuration */
510 	i2c_smbus_write_word_swapped(client, INA209_CONFIGURATION,
511 				     data->config_orig);
512 	i2c_smbus_write_word_swapped(client, INA209_CALIBRATION,
513 				     data->calibration_orig);
514 }
515 
516 static int ina209_init_client(struct i2c_client *client,
517 			      struct ina209_data *data)
518 {
519 	struct ina2xx_platform_data *pdata = dev_get_platdata(&client->dev);
520 	u32 shunt;
521 	int reg;
522 
523 	reg = i2c_smbus_read_word_swapped(client, INA209_CALIBRATION);
524 	if (reg < 0)
525 		return reg;
526 	data->calibration_orig = reg;
527 
528 	reg = i2c_smbus_read_word_swapped(client, INA209_CONFIGURATION);
529 	if (reg < 0)
530 		return reg;
531 	data->config_orig = reg;
532 
533 	if (pdata) {
534 		if (pdata->shunt_uohms <= 0)
535 			return -EINVAL;
536 		shunt = pdata->shunt_uohms;
537 	} else if (!of_property_read_u32(client->dev.of_node, "shunt-resistor",
538 					 &shunt)) {
539 		if (shunt == 0)
540 			return -EINVAL;
541 	} else {
542 		shunt = data->calibration_orig ?
543 		  40960000 / data->calibration_orig : INA209_SHUNT_DEFAULT;
544 	}
545 
546 	i2c_smbus_write_word_swapped(client, INA209_CONFIGURATION,
547 				     INA209_CONFIG_DEFAULT);
548 	data->update_interval = ina209_interval_from_reg(INA209_CONFIG_DEFAULT);
549 
550 	/*
551 	 * Calibrate current LSB to 1mA. Shunt is in uOhms.
552 	 * See equation 13 in datasheet.
553 	 */
554 	i2c_smbus_write_word_swapped(client, INA209_CALIBRATION,
555 				     clamp_val(40960000 / shunt, 1, 65535));
556 
557 	/* Clear status register */
558 	i2c_smbus_read_word_swapped(client, INA209_STATUS);
559 
560 	return 0;
561 }
562 
563 static int ina209_probe(struct i2c_client *client,
564 			const struct i2c_device_id *id)
565 {
566 	struct i2c_adapter *adapter = client->adapter;
567 	struct ina209_data *data;
568 	int ret;
569 
570 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WORD_DATA))
571 		return -ENODEV;
572 
573 	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
574 	if (!data)
575 		return -ENOMEM;
576 
577 	i2c_set_clientdata(client, data);
578 	mutex_init(&data->update_lock);
579 
580 	ret = ina209_init_client(client, data);
581 	if (ret)
582 		return ret;
583 
584 	/* Register sysfs hooks */
585 	ret = sysfs_create_group(&client->dev.kobj, &ina209_group);
586 	if (ret)
587 		goto out_restore_conf;
588 
589 	data->hwmon_dev = hwmon_device_register(&client->dev);
590 	if (IS_ERR(data->hwmon_dev)) {
591 		ret = PTR_ERR(data->hwmon_dev);
592 		goto out_hwmon_device_register;
593 	}
594 
595 	return 0;
596 
597 out_hwmon_device_register:
598 	sysfs_remove_group(&client->dev.kobj, &ina209_group);
599 out_restore_conf:
600 	ina209_restore_conf(client, data);
601 	return ret;
602 }
603 
604 static int ina209_remove(struct i2c_client *client)
605 {
606 	struct ina209_data *data = i2c_get_clientdata(client);
607 
608 	hwmon_device_unregister(data->hwmon_dev);
609 	sysfs_remove_group(&client->dev.kobj, &ina209_group);
610 	ina209_restore_conf(client, data);
611 
612 	return 0;
613 }
614 
615 static const struct i2c_device_id ina209_id[] = {
616 	{ "ina209", 0 },
617 	{ }
618 };
619 MODULE_DEVICE_TABLE(i2c, ina209_id);
620 
621 /* This is the driver that will be inserted */
622 static struct i2c_driver ina209_driver = {
623 	.class		= I2C_CLASS_HWMON,
624 	.driver = {
625 		.name	= "ina209",
626 	},
627 	.probe		= ina209_probe,
628 	.remove		= ina209_remove,
629 	.id_table	= ina209_id,
630 };
631 
632 module_i2c_driver(ina209_driver);
633 
634 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>, Paul Hays <Paul.Hays@cattail.ca>, Guenter Roeck <linux@roeck-us.net>");
635 MODULE_DESCRIPTION("INA209 driver");
636 MODULE_LICENSE("GPL");
637