1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Driver for Texas Instruments INA238 power monitor chip
4 * Datasheet: https://www.ti.com/product/ina238
5 *
6 * Copyright (C) 2021 Nathan Rossi <nathan.rossi@digi.com>
7 */
8
9 #include <linux/err.h>
10 #include <linux/hwmon.h>
11 #include <linux/i2c.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/of.h>
16 #include <linux/regmap.h>
17
18 #include <linux/platform_data/ina2xx.h>
19
20 /* INA238 register definitions */
21 #define INA238_CONFIG 0x0
22 #define INA238_ADC_CONFIG 0x1
23 #define INA238_SHUNT_CALIBRATION 0x2
24 #define INA238_SHUNT_VOLTAGE 0x4
25 #define INA238_BUS_VOLTAGE 0x5
26 #define INA238_DIE_TEMP 0x6
27 #define INA238_CURRENT 0x7
28 #define INA238_POWER 0x8
29 #define INA238_DIAG_ALERT 0xb
30 #define INA238_SHUNT_OVER_VOLTAGE 0xc
31 #define INA238_SHUNT_UNDER_VOLTAGE 0xd
32 #define INA238_BUS_OVER_VOLTAGE 0xe
33 #define INA238_BUS_UNDER_VOLTAGE 0xf
34 #define INA238_TEMP_LIMIT 0x10
35 #define INA238_POWER_LIMIT 0x11
36 #define INA238_DEVICE_ID 0x3f
37
38 #define INA238_CONFIG_ADCRANGE BIT(4)
39
40 #define INA238_DIAG_ALERT_TMPOL BIT(7)
41 #define INA238_DIAG_ALERT_SHNTOL BIT(6)
42 #define INA238_DIAG_ALERT_SHNTUL BIT(5)
43 #define INA238_DIAG_ALERT_BUSOL BIT(4)
44 #define INA238_DIAG_ALERT_BUSUL BIT(3)
45 #define INA238_DIAG_ALERT_POL BIT(2)
46
47 #define INA238_REGISTERS 0x11
48
49 #define INA238_RSHUNT_DEFAULT 10000 /* uOhm */
50
51 /* Default configuration of device on reset. */
52 #define INA238_CONFIG_DEFAULT 0
53 /* 16 sample averaging, 1052us conversion time, continuous mode */
54 #define INA238_ADC_CONFIG_DEFAULT 0xfb6a
55 /* Configure alerts to be based on averaged value (SLOWALERT) */
56 #define INA238_DIAG_ALERT_DEFAULT 0x2000
57 /*
58 * This driver uses a fixed calibration value in order to scale current/power
59 * based on a fixed shunt resistor value. This allows for conversion within the
60 * device to avoid integer limits whilst current/power accuracy is scaled
61 * relative to the shunt resistor value within the driver. This is similar to
62 * how the ina2xx driver handles current/power scaling.
63 *
64 * The end result of this is that increasing shunt values (from a fixed 20 mOhm
65 * shunt) increase the effective current/power accuracy whilst limiting the
66 * range and decreasing shunt values decrease the effective accuracy but
67 * increase the range.
68 *
69 * The value of the Current register is calculated given the following:
70 * Current (A) = (shunt voltage register * 5) * calibration / 81920
71 *
72 * The maximum shunt voltage is 163.835 mV (0x7fff, ADC_RANGE = 0, gain = 4).
73 * With the maximum current value of 0x7fff and a fixed shunt value results in
74 * a calibration value of 16384 (0x4000).
75 *
76 * 0x7fff = (0x7fff * 5) * calibration / 81920
77 * calibration = 0x4000
78 *
79 * Equivalent calibration is applied for the Power register (maximum value for
80 * bus voltage is 102396.875 mV, 0x7fff), where the maximum power that can
81 * occur is ~16776192 uW (register value 0x147a8):
82 *
83 * This scaling means the resulting values for Current and Power registers need
84 * to be scaled by the difference between the fixed shunt resistor and the
85 * actual shunt resistor:
86 *
87 * shunt = 0x4000 / (819.2 * 10^6) / 0.001 = 20000 uOhms (with 1mA/lsb)
88 *
89 * Current (mA) = register value * 20000 / rshunt / 4 * gain
90 * Power (W) = 0.2 * register value * 20000 / rshunt / 4 * gain
91 */
92 #define INA238_CALIBRATION_VALUE 16384
93 #define INA238_FIXED_SHUNT 20000
94
95 #define INA238_SHUNT_VOLTAGE_LSB 5 /* 5 uV/lsb */
96 #define INA238_BUS_VOLTAGE_LSB 3125 /* 3.125 mV/lsb */
97 #define INA238_DIE_TEMP_LSB 125 /* 125 mC/lsb */
98
99 static struct regmap_config ina238_regmap_config = {
100 .max_register = INA238_REGISTERS,
101 .reg_bits = 8,
102 .val_bits = 16,
103 };
104
105 struct ina238_data {
106 struct i2c_client *client;
107 struct mutex config_lock;
108 struct regmap *regmap;
109 u32 rshunt;
110 int gain;
111 };
112
ina238_read_reg24(const struct i2c_client * client,u8 reg,u32 * val)113 static int ina238_read_reg24(const struct i2c_client *client, u8 reg, u32 *val)
114 {
115 u8 data[3];
116 int err;
117
118 /* 24-bit register read */
119 err = i2c_smbus_read_i2c_block_data(client, reg, 3, data);
120 if (err < 0)
121 return err;
122 if (err != 3)
123 return -EIO;
124 *val = (data[0] << 16) | (data[1] << 8) | data[2];
125
126 return 0;
127 }
128
ina238_read_in(struct device * dev,u32 attr,int channel,long * val)129 static int ina238_read_in(struct device *dev, u32 attr, int channel,
130 long *val)
131 {
132 struct ina238_data *data = dev_get_drvdata(dev);
133 int reg, mask;
134 int regval;
135 int err;
136
137 switch (channel) {
138 case 0:
139 switch (attr) {
140 case hwmon_in_input:
141 reg = INA238_SHUNT_VOLTAGE;
142 break;
143 case hwmon_in_max:
144 reg = INA238_SHUNT_OVER_VOLTAGE;
145 break;
146 case hwmon_in_min:
147 reg = INA238_SHUNT_UNDER_VOLTAGE;
148 break;
149 case hwmon_in_max_alarm:
150 reg = INA238_DIAG_ALERT;
151 mask = INA238_DIAG_ALERT_SHNTOL;
152 break;
153 case hwmon_in_min_alarm:
154 reg = INA238_DIAG_ALERT;
155 mask = INA238_DIAG_ALERT_SHNTUL;
156 break;
157 default:
158 return -EOPNOTSUPP;
159 }
160 break;
161 case 1:
162 switch (attr) {
163 case hwmon_in_input:
164 reg = INA238_BUS_VOLTAGE;
165 break;
166 case hwmon_in_max:
167 reg = INA238_BUS_OVER_VOLTAGE;
168 break;
169 case hwmon_in_min:
170 reg = INA238_BUS_UNDER_VOLTAGE;
171 break;
172 case hwmon_in_max_alarm:
173 reg = INA238_DIAG_ALERT;
174 mask = INA238_DIAG_ALERT_BUSOL;
175 break;
176 case hwmon_in_min_alarm:
177 reg = INA238_DIAG_ALERT;
178 mask = INA238_DIAG_ALERT_BUSUL;
179 break;
180 default:
181 return -EOPNOTSUPP;
182 }
183 break;
184 default:
185 return -EOPNOTSUPP;
186 }
187
188 err = regmap_read(data->regmap, reg, ®val);
189 if (err < 0)
190 return err;
191
192 switch (attr) {
193 case hwmon_in_input:
194 case hwmon_in_max:
195 case hwmon_in_min:
196 /* signed register, value in mV */
197 regval = (s16)regval;
198 if (channel == 0)
199 /* gain of 1 -> LSB / 4 */
200 *val = (regval * INA238_SHUNT_VOLTAGE_LSB) /
201 (1000 * (4 - data->gain + 1));
202 else
203 *val = (regval * INA238_BUS_VOLTAGE_LSB) / 1000;
204 break;
205 case hwmon_in_max_alarm:
206 case hwmon_in_min_alarm:
207 *val = !!(regval & mask);
208 break;
209 }
210
211 return 0;
212 }
213
ina238_write_in(struct device * dev,u32 attr,int channel,long val)214 static int ina238_write_in(struct device *dev, u32 attr, int channel,
215 long val)
216 {
217 struct ina238_data *data = dev_get_drvdata(dev);
218 int regval;
219
220 if (attr != hwmon_in_max && attr != hwmon_in_min)
221 return -EOPNOTSUPP;
222
223 /* convert decimal to register value */
224 switch (channel) {
225 case 0:
226 /* signed value, clamp to max range +/-163 mV */
227 regval = clamp_val(val, -163, 163);
228 regval = (regval * 1000 * (4 - data->gain + 1)) /
229 INA238_SHUNT_VOLTAGE_LSB;
230 regval = clamp_val(regval, S16_MIN, S16_MAX);
231
232 switch (attr) {
233 case hwmon_in_max:
234 return regmap_write(data->regmap,
235 INA238_SHUNT_OVER_VOLTAGE, regval);
236 case hwmon_in_min:
237 return regmap_write(data->regmap,
238 INA238_SHUNT_UNDER_VOLTAGE, regval);
239 default:
240 return -EOPNOTSUPP;
241 }
242 case 1:
243 /* signed value, positive values only. Clamp to max 102.396 V */
244 regval = clamp_val(val, 0, 102396);
245 regval = (regval * 1000) / INA238_BUS_VOLTAGE_LSB;
246 regval = clamp_val(regval, 0, S16_MAX);
247
248 switch (attr) {
249 case hwmon_in_max:
250 return regmap_write(data->regmap,
251 INA238_BUS_OVER_VOLTAGE, regval);
252 case hwmon_in_min:
253 return regmap_write(data->regmap,
254 INA238_BUS_UNDER_VOLTAGE, regval);
255 default:
256 return -EOPNOTSUPP;
257 }
258 default:
259 return -EOPNOTSUPP;
260 }
261 }
262
ina238_read_current(struct device * dev,u32 attr,long * val)263 static int ina238_read_current(struct device *dev, u32 attr, long *val)
264 {
265 struct ina238_data *data = dev_get_drvdata(dev);
266 int regval;
267 int err;
268
269 switch (attr) {
270 case hwmon_curr_input:
271 err = regmap_read(data->regmap, INA238_CURRENT, ®val);
272 if (err < 0)
273 return err;
274
275 /* Signed register, fixed 1mA current lsb. result in mA */
276 *val = div_s64((s16)regval * INA238_FIXED_SHUNT * data->gain,
277 data->rshunt * 4);
278 break;
279 default:
280 return -EOPNOTSUPP;
281 }
282
283 return 0;
284 }
285
ina238_read_power(struct device * dev,u32 attr,long * val)286 static int ina238_read_power(struct device *dev, u32 attr, long *val)
287 {
288 struct ina238_data *data = dev_get_drvdata(dev);
289 long long power;
290 int regval;
291 int err;
292
293 switch (attr) {
294 case hwmon_power_input:
295 err = ina238_read_reg24(data->client, INA238_POWER, ®val);
296 if (err)
297 return err;
298
299 /* Fixed 1mA lsb, scaled by 1000000 to have result in uW */
300 power = div_u64(regval * 1000ULL * INA238_FIXED_SHUNT *
301 data->gain, 20 * data->rshunt);
302 /* Clamp value to maximum value of long */
303 *val = clamp_val(power, 0, LONG_MAX);
304 break;
305 case hwmon_power_max:
306 err = regmap_read(data->regmap, INA238_POWER_LIMIT, ®val);
307 if (err)
308 return err;
309
310 /*
311 * Truncated 24-bit compare register, lower 8-bits are
312 * truncated. Same conversion to/from uW as POWER register.
313 */
314 power = div_u64((regval << 8) * 1000ULL * INA238_FIXED_SHUNT *
315 data->gain, 20 * data->rshunt);
316 /* Clamp value to maximum value of long */
317 *val = clamp_val(power, 0, LONG_MAX);
318 break;
319 case hwmon_power_max_alarm:
320 err = regmap_read(data->regmap, INA238_DIAG_ALERT, ®val);
321 if (err)
322 return err;
323
324 *val = !!(regval & INA238_DIAG_ALERT_POL);
325 break;
326 default:
327 return -EOPNOTSUPP;
328 }
329
330 return 0;
331 }
332
ina238_write_power(struct device * dev,u32 attr,long val)333 static int ina238_write_power(struct device *dev, u32 attr, long val)
334 {
335 struct ina238_data *data = dev_get_drvdata(dev);
336 long regval;
337
338 if (attr != hwmon_power_max)
339 return -EOPNOTSUPP;
340
341 /*
342 * Unsigned postive values. Compared against the 24-bit power register,
343 * lower 8-bits are truncated. Same conversion to/from uW as POWER
344 * register.
345 */
346 regval = clamp_val(val, 0, LONG_MAX);
347 regval = div_u64(val * 20ULL * data->rshunt,
348 1000ULL * INA238_FIXED_SHUNT * data->gain);
349 regval = clamp_val(regval >> 8, 0, U16_MAX);
350
351 return regmap_write(data->regmap, INA238_POWER_LIMIT, regval);
352 }
353
ina238_read_temp(struct device * dev,u32 attr,long * val)354 static int ina238_read_temp(struct device *dev, u32 attr, long *val)
355 {
356 struct ina238_data *data = dev_get_drvdata(dev);
357 int regval;
358 int err;
359
360 switch (attr) {
361 case hwmon_temp_input:
362 err = regmap_read(data->regmap, INA238_DIE_TEMP, ®val);
363 if (err)
364 return err;
365
366 /* Signed, bits 15-4 of register, result in mC */
367 *val = ((s16)regval >> 4) * INA238_DIE_TEMP_LSB;
368 break;
369 case hwmon_temp_max:
370 err = regmap_read(data->regmap, INA238_TEMP_LIMIT, ®val);
371 if (err)
372 return err;
373
374 /* Signed, bits 15-4 of register, result in mC */
375 *val = ((s16)regval >> 4) * INA238_DIE_TEMP_LSB;
376 break;
377 case hwmon_temp_max_alarm:
378 err = regmap_read(data->regmap, INA238_DIAG_ALERT, ®val);
379 if (err)
380 return err;
381
382 *val = !!(regval & INA238_DIAG_ALERT_TMPOL);
383 break;
384 default:
385 return -EOPNOTSUPP;
386 }
387
388 return 0;
389 }
390
ina238_write_temp(struct device * dev,u32 attr,long val)391 static int ina238_write_temp(struct device *dev, u32 attr, long val)
392 {
393 struct ina238_data *data = dev_get_drvdata(dev);
394 int regval;
395
396 if (attr != hwmon_temp_max)
397 return -EOPNOTSUPP;
398
399 /* Signed, bits 15-4 of register */
400 regval = (val / INA238_DIE_TEMP_LSB) << 4;
401 regval = clamp_val(regval, S16_MIN, S16_MAX) & 0xfff0;
402
403 return regmap_write(data->regmap, INA238_TEMP_LIMIT, regval);
404 }
405
ina238_read(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long * val)406 static int ina238_read(struct device *dev, enum hwmon_sensor_types type,
407 u32 attr, int channel, long *val)
408 {
409 switch (type) {
410 case hwmon_in:
411 return ina238_read_in(dev, attr, channel, val);
412 case hwmon_curr:
413 return ina238_read_current(dev, attr, val);
414 case hwmon_power:
415 return ina238_read_power(dev, attr, val);
416 case hwmon_temp:
417 return ina238_read_temp(dev, attr, val);
418 default:
419 return -EOPNOTSUPP;
420 }
421 return 0;
422 }
423
ina238_write(struct device * dev,enum hwmon_sensor_types type,u32 attr,int channel,long val)424 static int ina238_write(struct device *dev, enum hwmon_sensor_types type,
425 u32 attr, int channel, long val)
426 {
427 struct ina238_data *data = dev_get_drvdata(dev);
428 int err;
429
430 mutex_lock(&data->config_lock);
431
432 switch (type) {
433 case hwmon_in:
434 err = ina238_write_in(dev, attr, channel, val);
435 break;
436 case hwmon_power:
437 err = ina238_write_power(dev, attr, val);
438 break;
439 case hwmon_temp:
440 err = ina238_write_temp(dev, attr, val);
441 break;
442 default:
443 err = -EOPNOTSUPP;
444 break;
445 }
446
447 mutex_unlock(&data->config_lock);
448 return err;
449 }
450
ina238_is_visible(const void * drvdata,enum hwmon_sensor_types type,u32 attr,int channel)451 static umode_t ina238_is_visible(const void *drvdata,
452 enum hwmon_sensor_types type,
453 u32 attr, int channel)
454 {
455 switch (type) {
456 case hwmon_in:
457 switch (attr) {
458 case hwmon_in_input:
459 case hwmon_in_max_alarm:
460 case hwmon_in_min_alarm:
461 return 0444;
462 case hwmon_in_max:
463 case hwmon_in_min:
464 return 0644;
465 default:
466 return 0;
467 }
468 case hwmon_curr:
469 switch (attr) {
470 case hwmon_curr_input:
471 return 0444;
472 default:
473 return 0;
474 }
475 case hwmon_power:
476 switch (attr) {
477 case hwmon_power_input:
478 case hwmon_power_max_alarm:
479 return 0444;
480 case hwmon_power_max:
481 return 0644;
482 default:
483 return 0;
484 }
485 case hwmon_temp:
486 switch (attr) {
487 case hwmon_temp_input:
488 case hwmon_temp_max_alarm:
489 return 0444;
490 case hwmon_temp_max:
491 return 0644;
492 default:
493 return 0;
494 }
495 default:
496 return 0;
497 }
498 }
499
500 #define INA238_HWMON_IN_CONFIG (HWMON_I_INPUT | \
501 HWMON_I_MAX | HWMON_I_MAX_ALARM | \
502 HWMON_I_MIN | HWMON_I_MIN_ALARM)
503
504 static const struct hwmon_channel_info * const ina238_info[] = {
505 HWMON_CHANNEL_INFO(in,
506 /* 0: shunt voltage */
507 INA238_HWMON_IN_CONFIG,
508 /* 1: bus voltage */
509 INA238_HWMON_IN_CONFIG),
510 HWMON_CHANNEL_INFO(curr,
511 /* 0: current through shunt */
512 HWMON_C_INPUT),
513 HWMON_CHANNEL_INFO(power,
514 /* 0: power */
515 HWMON_P_INPUT | HWMON_P_MAX | HWMON_P_MAX_ALARM),
516 HWMON_CHANNEL_INFO(temp,
517 /* 0: die temperature */
518 HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_ALARM),
519 NULL
520 };
521
522 static const struct hwmon_ops ina238_hwmon_ops = {
523 .is_visible = ina238_is_visible,
524 .read = ina238_read,
525 .write = ina238_write,
526 };
527
528 static const struct hwmon_chip_info ina238_chip_info = {
529 .ops = &ina238_hwmon_ops,
530 .info = ina238_info,
531 };
532
ina238_probe(struct i2c_client * client)533 static int ina238_probe(struct i2c_client *client)
534 {
535 struct ina2xx_platform_data *pdata = dev_get_platdata(&client->dev);
536 struct device *dev = &client->dev;
537 struct device *hwmon_dev;
538 struct ina238_data *data;
539 int config;
540 int ret;
541
542 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
543 if (!data)
544 return -ENOMEM;
545
546 data->client = client;
547 mutex_init(&data->config_lock);
548
549 data->regmap = devm_regmap_init_i2c(client, &ina238_regmap_config);
550 if (IS_ERR(data->regmap)) {
551 dev_err(dev, "failed to allocate register map\n");
552 return PTR_ERR(data->regmap);
553 }
554
555 /* load shunt value */
556 data->rshunt = INA238_RSHUNT_DEFAULT;
557 if (device_property_read_u32(dev, "shunt-resistor", &data->rshunt) < 0 && pdata)
558 data->rshunt = pdata->shunt_uohms;
559 if (data->rshunt == 0) {
560 dev_err(dev, "invalid shunt resister value %u\n", data->rshunt);
561 return -EINVAL;
562 }
563
564 /* load shunt gain value */
565 if (device_property_read_u32(dev, "ti,shunt-gain", &data->gain) < 0)
566 data->gain = 4; /* Default of ADCRANGE = 0 */
567 if (data->gain != 1 && data->gain != 4) {
568 dev_err(dev, "invalid shunt gain value %u\n", data->gain);
569 return -EINVAL;
570 }
571
572 /* Setup CONFIG register */
573 config = INA238_CONFIG_DEFAULT;
574 if (data->gain == 1)
575 config |= INA238_CONFIG_ADCRANGE; /* ADCRANGE = 1 is /1 */
576 ret = regmap_write(data->regmap, INA238_CONFIG, config);
577 if (ret < 0) {
578 dev_err(dev, "error configuring the device: %d\n", ret);
579 return -ENODEV;
580 }
581
582 /* Setup ADC_CONFIG register */
583 ret = regmap_write(data->regmap, INA238_ADC_CONFIG,
584 INA238_ADC_CONFIG_DEFAULT);
585 if (ret < 0) {
586 dev_err(dev, "error configuring the device: %d\n", ret);
587 return -ENODEV;
588 }
589
590 /* Setup SHUNT_CALIBRATION register with fixed value */
591 ret = regmap_write(data->regmap, INA238_SHUNT_CALIBRATION,
592 INA238_CALIBRATION_VALUE);
593 if (ret < 0) {
594 dev_err(dev, "error configuring the device: %d\n", ret);
595 return -ENODEV;
596 }
597
598 /* Setup alert/alarm configuration */
599 ret = regmap_write(data->regmap, INA238_DIAG_ALERT,
600 INA238_DIAG_ALERT_DEFAULT);
601 if (ret < 0) {
602 dev_err(dev, "error configuring the device: %d\n", ret);
603 return -ENODEV;
604 }
605
606 hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
607 &ina238_chip_info,
608 NULL);
609 if (IS_ERR(hwmon_dev))
610 return PTR_ERR(hwmon_dev);
611
612 dev_info(dev, "power monitor %s (Rshunt = %u uOhm, gain = %u)\n",
613 client->name, data->rshunt, data->gain);
614
615 return 0;
616 }
617
618 static const struct i2c_device_id ina238_id[] = {
619 { "ina238", 0 },
620 { }
621 };
622 MODULE_DEVICE_TABLE(i2c, ina238_id);
623
624 static const struct of_device_id __maybe_unused ina238_of_match[] = {
625 { .compatible = "ti,ina238" },
626 { },
627 };
628 MODULE_DEVICE_TABLE(of, ina238_of_match);
629
630 static struct i2c_driver ina238_driver = {
631 .class = I2C_CLASS_HWMON,
632 .driver = {
633 .name = "ina238",
634 .of_match_table = of_match_ptr(ina238_of_match),
635 },
636 .probe = ina238_probe,
637 .id_table = ina238_id,
638 };
639
640 module_i2c_driver(ina238_driver);
641
642 MODULE_AUTHOR("Nathan Rossi <nathan.rossi@digi.com>");
643 MODULE_DESCRIPTION("ina238 driver");
644 MODULE_LICENSE("GPL");
645