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/err.h>
20 #include <linux/slab.h>
21 #include <linux/i2c.h>
22 #include <linux/hwmon.h>
23 #include <linux/hwmon-sysfs.h>
24 #include <linux/i2c/ltc4245.h>
25
26 /* Here are names of the chip's registers (a.k.a. commands) */
27 enum ltc4245_cmd {
28 LTC4245_STATUS = 0x00, /* readonly */
29 LTC4245_ALERT = 0x01,
30 LTC4245_CONTROL = 0x02,
31 LTC4245_ON = 0x03,
32 LTC4245_FAULT1 = 0x04,
33 LTC4245_FAULT2 = 0x05,
34 LTC4245_GPIO = 0x06,
35 LTC4245_ADCADR = 0x07,
36
37 LTC4245_12VIN = 0x10,
38 LTC4245_12VSENSE = 0x11,
39 LTC4245_12VOUT = 0x12,
40 LTC4245_5VIN = 0x13,
41 LTC4245_5VSENSE = 0x14,
42 LTC4245_5VOUT = 0x15,
43 LTC4245_3VIN = 0x16,
44 LTC4245_3VSENSE = 0x17,
45 LTC4245_3VOUT = 0x18,
46 LTC4245_VEEIN = 0x19,
47 LTC4245_VEESENSE = 0x1a,
48 LTC4245_VEEOUT = 0x1b,
49 LTC4245_GPIOADC = 0x1c,
50 };
51
52 struct ltc4245_data {
53 struct device *hwmon_dev;
54
55 struct mutex update_lock;
56 bool valid;
57 unsigned long last_updated; /* in jiffies */
58
59 /* Control registers */
60 u8 cregs[0x08];
61
62 /* Voltage registers */
63 u8 vregs[0x0d];
64
65 /* GPIO ADC registers */
66 bool use_extra_gpios;
67 int gpios[3];
68 };
69
70 /*
71 * Update the readings from the GPIO pins. If the driver has been configured to
72 * sample all GPIO's as analog voltages, a round-robin sampling method is used.
73 * Otherwise, only the configured GPIO pin is sampled.
74 *
75 * LOCKING: must hold data->update_lock
76 */
ltc4245_update_gpios(struct device * dev)77 static void ltc4245_update_gpios(struct device *dev)
78 {
79 struct i2c_client *client = to_i2c_client(dev);
80 struct ltc4245_data *data = i2c_get_clientdata(client);
81 u8 gpio_curr, gpio_next, gpio_reg;
82 int i;
83
84 /* no extra gpio support, we're basically done */
85 if (!data->use_extra_gpios) {
86 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
87 return;
88 }
89
90 /*
91 * If the last reading was too long ago, then we mark all old GPIO
92 * readings as stale by setting them to -EAGAIN
93 */
94 if (time_after(jiffies, data->last_updated + 5 * HZ)) {
95 dev_dbg(&client->dev, "Marking GPIOs invalid\n");
96 for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
97 data->gpios[i] = -EAGAIN;
98 }
99
100 /*
101 * Get the current GPIO pin
102 *
103 * The datasheet calls these GPIO[1-3], but we'll calculate the zero
104 * based array index instead, and call them GPIO[0-2]. This is much
105 * easier to think about.
106 */
107 gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
108 if (gpio_curr > 0)
109 gpio_curr -= 1;
110
111 /* Read the GPIO voltage from the GPIOADC register */
112 data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];
113
114 /* Find the next GPIO pin to read */
115 gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);
116
117 /*
118 * Calculate the correct setting for the GPIO register so it will
119 * sample the next GPIO pin
120 */
121 gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);
122
123 /* Update the GPIO register */
124 i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);
125
126 /* Update saved data */
127 data->cregs[LTC4245_GPIO] = gpio_reg;
128 }
129
ltc4245_update_device(struct device * dev)130 static struct ltc4245_data *ltc4245_update_device(struct device *dev)
131 {
132 struct i2c_client *client = to_i2c_client(dev);
133 struct ltc4245_data *data = i2c_get_clientdata(client);
134 s32 val;
135 int i;
136
137 mutex_lock(&data->update_lock);
138
139 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
140
141 dev_dbg(&client->dev, "Starting ltc4245 update\n");
142
143 /* Read control registers -- 0x00 to 0x07 */
144 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
145 val = i2c_smbus_read_byte_data(client, i);
146 if (unlikely(val < 0))
147 data->cregs[i] = 0;
148 else
149 data->cregs[i] = val;
150 }
151
152 /* Read voltage registers -- 0x10 to 0x1c */
153 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
154 val = i2c_smbus_read_byte_data(client, i+0x10);
155 if (unlikely(val < 0))
156 data->vregs[i] = 0;
157 else
158 data->vregs[i] = val;
159 }
160
161 /* Update GPIO readings */
162 ltc4245_update_gpios(dev);
163
164 data->last_updated = jiffies;
165 data->valid = 1;
166 }
167
168 mutex_unlock(&data->update_lock);
169
170 return data;
171 }
172
173 /* Return the voltage from the given register in millivolts */
ltc4245_get_voltage(struct device * dev,u8 reg)174 static int ltc4245_get_voltage(struct device *dev, u8 reg)
175 {
176 struct ltc4245_data *data = ltc4245_update_device(dev);
177 const u8 regval = data->vregs[reg - 0x10];
178 u32 voltage = 0;
179
180 switch (reg) {
181 case LTC4245_12VIN:
182 case LTC4245_12VOUT:
183 voltage = regval * 55;
184 break;
185 case LTC4245_5VIN:
186 case LTC4245_5VOUT:
187 voltage = regval * 22;
188 break;
189 case LTC4245_3VIN:
190 case LTC4245_3VOUT:
191 voltage = regval * 15;
192 break;
193 case LTC4245_VEEIN:
194 case LTC4245_VEEOUT:
195 voltage = regval * -55;
196 break;
197 case LTC4245_GPIOADC:
198 voltage = regval * 10;
199 break;
200 default:
201 /* If we get here, the developer messed up */
202 WARN_ON_ONCE(1);
203 break;
204 }
205
206 return voltage;
207 }
208
209 /* Return the current in the given sense register in milliAmperes */
ltc4245_get_current(struct device * dev,u8 reg)210 static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
211 {
212 struct ltc4245_data *data = ltc4245_update_device(dev);
213 const u8 regval = data->vregs[reg - 0x10];
214 unsigned int voltage;
215 unsigned int curr;
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
ltc4245_show_voltage(struct device * dev,struct device_attribute * da,char * buf)258 static ssize_t ltc4245_show_voltage(struct device *dev,
259 struct device_attribute *da,
260 char *buf)
261 {
262 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
263 const int voltage = ltc4245_get_voltage(dev, attr->index);
264
265 return snprintf(buf, PAGE_SIZE, "%d\n", voltage);
266 }
267
ltc4245_show_current(struct device * dev,struct device_attribute * da,char * buf)268 static ssize_t ltc4245_show_current(struct device *dev,
269 struct device_attribute *da,
270 char *buf)
271 {
272 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
273 const unsigned int curr = ltc4245_get_current(dev, attr->index);
274
275 return snprintf(buf, PAGE_SIZE, "%u\n", curr);
276 }
277
ltc4245_show_power(struct device * dev,struct device_attribute * da,char * buf)278 static ssize_t ltc4245_show_power(struct device *dev,
279 struct device_attribute *da,
280 char *buf)
281 {
282 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
283 const unsigned int curr = ltc4245_get_current(dev, attr->index);
284 const int output_voltage = ltc4245_get_voltage(dev, attr->index+1);
285
286 /* current in mA * voltage in mV == power in uW */
287 const unsigned int power = abs(output_voltage * curr);
288
289 return snprintf(buf, PAGE_SIZE, "%u\n", power);
290 }
291
ltc4245_show_alarm(struct device * dev,struct device_attribute * da,char * buf)292 static ssize_t ltc4245_show_alarm(struct device *dev,
293 struct device_attribute *da,
294 char *buf)
295 {
296 struct sensor_device_attribute_2 *attr = to_sensor_dev_attr_2(da);
297 struct ltc4245_data *data = ltc4245_update_device(dev);
298 const u8 reg = data->cregs[attr->index];
299 const u32 mask = attr->nr;
300
301 return snprintf(buf, PAGE_SIZE, "%u\n", (reg & mask) ? 1 : 0);
302 }
303
ltc4245_show_gpio(struct device * dev,struct device_attribute * da,char * buf)304 static ssize_t ltc4245_show_gpio(struct device *dev,
305 struct device_attribute *da,
306 char *buf)
307 {
308 struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
309 struct ltc4245_data *data = ltc4245_update_device(dev);
310 int val = data->gpios[attr->index];
311
312 /* handle stale GPIO's */
313 if (val < 0)
314 return val;
315
316 /* Convert to millivolts and print */
317 return snprintf(buf, PAGE_SIZE, "%u\n", val * 10);
318 }
319
320 /* These macros are used below in constructing device attribute objects
321 * for use with sysfs_create_group() to make a sysfs device file
322 * for each register.
323 */
324
325 #define LTC4245_VOLTAGE(name, ltc4245_cmd_idx) \
326 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
327 ltc4245_show_voltage, NULL, ltc4245_cmd_idx)
328
329 #define LTC4245_CURRENT(name, ltc4245_cmd_idx) \
330 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
331 ltc4245_show_current, NULL, ltc4245_cmd_idx)
332
333 #define LTC4245_POWER(name, ltc4245_cmd_idx) \
334 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
335 ltc4245_show_power, NULL, ltc4245_cmd_idx)
336
337 #define LTC4245_ALARM(name, mask, reg) \
338 static SENSOR_DEVICE_ATTR_2(name, S_IRUGO, \
339 ltc4245_show_alarm, NULL, (mask), reg)
340
341 #define LTC4245_GPIO_VOLTAGE(name, gpio_num) \
342 static SENSOR_DEVICE_ATTR(name, S_IRUGO, \
343 ltc4245_show_gpio, NULL, gpio_num)
344
345 /* Construct a sensor_device_attribute structure for each register */
346
347 /* Input voltages */
348 LTC4245_VOLTAGE(in1_input, LTC4245_12VIN);
349 LTC4245_VOLTAGE(in2_input, LTC4245_5VIN);
350 LTC4245_VOLTAGE(in3_input, LTC4245_3VIN);
351 LTC4245_VOLTAGE(in4_input, LTC4245_VEEIN);
352
353 /* Input undervoltage alarms */
354 LTC4245_ALARM(in1_min_alarm, (1 << 0), LTC4245_FAULT1);
355 LTC4245_ALARM(in2_min_alarm, (1 << 1), LTC4245_FAULT1);
356 LTC4245_ALARM(in3_min_alarm, (1 << 2), LTC4245_FAULT1);
357 LTC4245_ALARM(in4_min_alarm, (1 << 3), LTC4245_FAULT1);
358
359 /* Currents (via sense resistor) */
360 LTC4245_CURRENT(curr1_input, LTC4245_12VSENSE);
361 LTC4245_CURRENT(curr2_input, LTC4245_5VSENSE);
362 LTC4245_CURRENT(curr3_input, LTC4245_3VSENSE);
363 LTC4245_CURRENT(curr4_input, LTC4245_VEESENSE);
364
365 /* Overcurrent alarms */
366 LTC4245_ALARM(curr1_max_alarm, (1 << 4), LTC4245_FAULT1);
367 LTC4245_ALARM(curr2_max_alarm, (1 << 5), LTC4245_FAULT1);
368 LTC4245_ALARM(curr3_max_alarm, (1 << 6), LTC4245_FAULT1);
369 LTC4245_ALARM(curr4_max_alarm, (1 << 7), LTC4245_FAULT1);
370
371 /* Output voltages */
372 LTC4245_VOLTAGE(in5_input, LTC4245_12VOUT);
373 LTC4245_VOLTAGE(in6_input, LTC4245_5VOUT);
374 LTC4245_VOLTAGE(in7_input, LTC4245_3VOUT);
375 LTC4245_VOLTAGE(in8_input, LTC4245_VEEOUT);
376
377 /* Power Bad alarms */
378 LTC4245_ALARM(in5_min_alarm, (1 << 0), LTC4245_FAULT2);
379 LTC4245_ALARM(in6_min_alarm, (1 << 1), LTC4245_FAULT2);
380 LTC4245_ALARM(in7_min_alarm, (1 << 2), LTC4245_FAULT2);
381 LTC4245_ALARM(in8_min_alarm, (1 << 3), LTC4245_FAULT2);
382
383 /* GPIO voltages */
384 LTC4245_GPIO_VOLTAGE(in9_input, 0);
385 LTC4245_GPIO_VOLTAGE(in10_input, 1);
386 LTC4245_GPIO_VOLTAGE(in11_input, 2);
387
388 /* Power Consumption (virtual) */
389 LTC4245_POWER(power1_input, LTC4245_12VSENSE);
390 LTC4245_POWER(power2_input, LTC4245_5VSENSE);
391 LTC4245_POWER(power3_input, LTC4245_3VSENSE);
392 LTC4245_POWER(power4_input, LTC4245_VEESENSE);
393
394 /* Finally, construct an array of pointers to members of the above objects,
395 * as required for sysfs_create_group()
396 */
397 static struct attribute *ltc4245_std_attributes[] = {
398 &sensor_dev_attr_in1_input.dev_attr.attr,
399 &sensor_dev_attr_in2_input.dev_attr.attr,
400 &sensor_dev_attr_in3_input.dev_attr.attr,
401 &sensor_dev_attr_in4_input.dev_attr.attr,
402
403 &sensor_dev_attr_in1_min_alarm.dev_attr.attr,
404 &sensor_dev_attr_in2_min_alarm.dev_attr.attr,
405 &sensor_dev_attr_in3_min_alarm.dev_attr.attr,
406 &sensor_dev_attr_in4_min_alarm.dev_attr.attr,
407
408 &sensor_dev_attr_curr1_input.dev_attr.attr,
409 &sensor_dev_attr_curr2_input.dev_attr.attr,
410 &sensor_dev_attr_curr3_input.dev_attr.attr,
411 &sensor_dev_attr_curr4_input.dev_attr.attr,
412
413 &sensor_dev_attr_curr1_max_alarm.dev_attr.attr,
414 &sensor_dev_attr_curr2_max_alarm.dev_attr.attr,
415 &sensor_dev_attr_curr3_max_alarm.dev_attr.attr,
416 &sensor_dev_attr_curr4_max_alarm.dev_attr.attr,
417
418 &sensor_dev_attr_in5_input.dev_attr.attr,
419 &sensor_dev_attr_in6_input.dev_attr.attr,
420 &sensor_dev_attr_in7_input.dev_attr.attr,
421 &sensor_dev_attr_in8_input.dev_attr.attr,
422
423 &sensor_dev_attr_in5_min_alarm.dev_attr.attr,
424 &sensor_dev_attr_in6_min_alarm.dev_attr.attr,
425 &sensor_dev_attr_in7_min_alarm.dev_attr.attr,
426 &sensor_dev_attr_in8_min_alarm.dev_attr.attr,
427
428 &sensor_dev_attr_in9_input.dev_attr.attr,
429
430 &sensor_dev_attr_power1_input.dev_attr.attr,
431 &sensor_dev_attr_power2_input.dev_attr.attr,
432 &sensor_dev_attr_power3_input.dev_attr.attr,
433 &sensor_dev_attr_power4_input.dev_attr.attr,
434
435 NULL,
436 };
437
438 static struct attribute *ltc4245_gpio_attributes[] = {
439 &sensor_dev_attr_in10_input.dev_attr.attr,
440 &sensor_dev_attr_in11_input.dev_attr.attr,
441 NULL,
442 };
443
444 static const struct attribute_group ltc4245_std_group = {
445 .attrs = ltc4245_std_attributes,
446 };
447
448 static const struct attribute_group ltc4245_gpio_group = {
449 .attrs = ltc4245_gpio_attributes,
450 };
451
ltc4245_sysfs_create_groups(struct i2c_client * client)452 static int ltc4245_sysfs_create_groups(struct i2c_client *client)
453 {
454 struct ltc4245_data *data = i2c_get_clientdata(client);
455 struct device *dev = &client->dev;
456 int ret;
457
458 /* register the standard sysfs attributes */
459 ret = sysfs_create_group(&dev->kobj, <c4245_std_group);
460 if (ret) {
461 dev_err(dev, "unable to register standard attributes\n");
462 return ret;
463 }
464
465 /* if we're using the extra gpio support, register it's attributes */
466 if (data->use_extra_gpios) {
467 ret = sysfs_create_group(&dev->kobj, <c4245_gpio_group);
468 if (ret) {
469 dev_err(dev, "unable to register gpio attributes\n");
470 sysfs_remove_group(&dev->kobj, <c4245_std_group);
471 return ret;
472 }
473 }
474
475 return 0;
476 }
477
ltc4245_sysfs_remove_groups(struct i2c_client * client)478 static void ltc4245_sysfs_remove_groups(struct i2c_client *client)
479 {
480 struct ltc4245_data *data = i2c_get_clientdata(client);
481 struct device *dev = &client->dev;
482
483 if (data->use_extra_gpios)
484 sysfs_remove_group(&dev->kobj, <c4245_gpio_group);
485
486 sysfs_remove_group(&dev->kobj, <c4245_std_group);
487 }
488
ltc4245_use_extra_gpios(struct i2c_client * client)489 static bool ltc4245_use_extra_gpios(struct i2c_client *client)
490 {
491 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
492 #ifdef CONFIG_OF
493 struct device_node *np = client->dev.of_node;
494 #endif
495
496 /* prefer platform data */
497 if (pdata)
498 return pdata->use_extra_gpios;
499
500 #ifdef CONFIG_OF
501 /* fallback on OF */
502 if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
503 return true;
504 #endif
505
506 return false;
507 }
508
ltc4245_probe(struct i2c_client * client,const struct i2c_device_id * id)509 static int ltc4245_probe(struct i2c_client *client,
510 const struct i2c_device_id *id)
511 {
512 struct i2c_adapter *adapter = client->adapter;
513 struct ltc4245_data *data;
514 int ret;
515
516 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
517 return -ENODEV;
518
519 data = kzalloc(sizeof(*data), GFP_KERNEL);
520 if (!data) {
521 ret = -ENOMEM;
522 goto out_kzalloc;
523 }
524
525 i2c_set_clientdata(client, data);
526 mutex_init(&data->update_lock);
527 data->use_extra_gpios = ltc4245_use_extra_gpios(client);
528
529 /* Initialize the LTC4245 chip */
530 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
531 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
532
533 /* Register sysfs hooks */
534 ret = ltc4245_sysfs_create_groups(client);
535 if (ret)
536 goto out_sysfs_create_groups;
537
538 data->hwmon_dev = hwmon_device_register(&client->dev);
539 if (IS_ERR(data->hwmon_dev)) {
540 ret = PTR_ERR(data->hwmon_dev);
541 goto out_hwmon_device_register;
542 }
543
544 return 0;
545
546 out_hwmon_device_register:
547 ltc4245_sysfs_remove_groups(client);
548 out_sysfs_create_groups:
549 kfree(data);
550 out_kzalloc:
551 return ret;
552 }
553
ltc4245_remove(struct i2c_client * client)554 static int ltc4245_remove(struct i2c_client *client)
555 {
556 struct ltc4245_data *data = i2c_get_clientdata(client);
557
558 hwmon_device_unregister(data->hwmon_dev);
559 ltc4245_sysfs_remove_groups(client);
560 kfree(data);
561
562 return 0;
563 }
564
565 static const struct i2c_device_id ltc4245_id[] = {
566 { "ltc4245", 0 },
567 { }
568 };
569 MODULE_DEVICE_TABLE(i2c, ltc4245_id);
570
571 /* This is the driver that will be inserted */
572 static struct i2c_driver ltc4245_driver = {
573 .driver = {
574 .name = "ltc4245",
575 },
576 .probe = ltc4245_probe,
577 .remove = ltc4245_remove,
578 .id_table = ltc4245_id,
579 };
580
ltc4245_init(void)581 static int __init ltc4245_init(void)
582 {
583 return i2c_add_driver(<c4245_driver);
584 }
585
ltc4245_exit(void)586 static void __exit ltc4245_exit(void)
587 {
588 i2c_del_driver(<c4245_driver);
589 }
590
591 MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
592 MODULE_DESCRIPTION("LTC4245 driver");
593 MODULE_LICENSE("GPL");
594
595 module_init(ltc4245_init);
596 module_exit(ltc4245_exit);
597