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/bitops.h>
20#include <linux/err.h>
21#include <linux/slab.h>
22#include <linux/i2c.h>
23#include <linux/hwmon.h>
24#include <linux/hwmon-sysfs.h>
25#include <linux/jiffies.h>
26#include <linux/platform_data/ltc4245.h>
27
28/* Here are names of the chip's registers (a.k.a. commands) */
29enum ltc4245_cmd {
30 LTC4245_STATUS = 0x00, /* readonly */
31 LTC4245_ALERT = 0x01,
32 LTC4245_CONTROL = 0x02,
33 LTC4245_ON = 0x03,
34 LTC4245_FAULT1 = 0x04,
35 LTC4245_FAULT2 = 0x05,
36 LTC4245_GPIO = 0x06,
37 LTC4245_ADCADR = 0x07,
38
39 LTC4245_12VIN = 0x10,
40 LTC4245_12VSENSE = 0x11,
41 LTC4245_12VOUT = 0x12,
42 LTC4245_5VIN = 0x13,
43 LTC4245_5VSENSE = 0x14,
44 LTC4245_5VOUT = 0x15,
45 LTC4245_3VIN = 0x16,
46 LTC4245_3VSENSE = 0x17,
47 LTC4245_3VOUT = 0x18,
48 LTC4245_VEEIN = 0x19,
49 LTC4245_VEESENSE = 0x1a,
50 LTC4245_VEEOUT = 0x1b,
51 LTC4245_GPIOADC = 0x1c,
52};
53
54struct ltc4245_data {
55 struct i2c_client *client;
56
57 struct mutex update_lock;
58 bool valid;
59 unsigned long last_updated; /* in jiffies */
60
61 /* Control registers */
62 u8 cregs[0x08];
63
64 /* Voltage registers */
65 u8 vregs[0x0d];
66
67 /* GPIO ADC registers */
68 bool use_extra_gpios;
69 int gpios[3];
70};
71
72/*
73 * Update the readings from the GPIO pins. If the driver has been configured to
74 * sample all GPIO's as analog voltages, a round-robin sampling method is used.
75 * Otherwise, only the configured GPIO pin is sampled.
76 *
77 * LOCKING: must hold data->update_lock
78 */
79static void ltc4245_update_gpios(struct device *dev)
80{
81 struct ltc4245_data *data = dev_get_drvdata(dev);
82 struct i2c_client *client = data->client;
83 u8 gpio_curr, gpio_next, gpio_reg;
84 int i;
85
86 /* no extra gpio support, we're basically done */
87 if (!data->use_extra_gpios) {
88 data->gpios[0] = data->vregs[LTC4245_GPIOADC - 0x10];
89 return;
90 }
91
92 /*
93 * If the last reading was too long ago, then we mark all old GPIO
94 * readings as stale by setting them to -EAGAIN
95 */
96 if (time_after(jiffies, data->last_updated + 5 * HZ)) {
97 for (i = 0; i < ARRAY_SIZE(data->gpios); i++)
98 data->gpios[i] = -EAGAIN;
99 }
100
101 /*
102 * Get the current GPIO pin
103 *
104 * The datasheet calls these GPIO[1-3], but we'll calculate the zero
105 * based array index instead, and call them GPIO[0-2]. This is much
106 * easier to think about.
107 */
108 gpio_curr = (data->cregs[LTC4245_GPIO] & 0xc0) >> 6;
109 if (gpio_curr > 0)
110 gpio_curr -= 1;
111
112 /* Read the GPIO voltage from the GPIOADC register */
113 data->gpios[gpio_curr] = data->vregs[LTC4245_GPIOADC - 0x10];
114
115 /* Find the next GPIO pin to read */
116 gpio_next = (gpio_curr + 1) % ARRAY_SIZE(data->gpios);
117
118 /*
119 * Calculate the correct setting for the GPIO register so it will
120 * sample the next GPIO pin
121 */
122 gpio_reg = (data->cregs[LTC4245_GPIO] & 0x3f) | ((gpio_next + 1) << 6);
123
124 /* Update the GPIO register */
125 i2c_smbus_write_byte_data(client, LTC4245_GPIO, gpio_reg);
126
127 /* Update saved data */
128 data->cregs[LTC4245_GPIO] = gpio_reg;
129}
130
131static struct ltc4245_data *ltc4245_update_device(struct device *dev)
132{
133 struct ltc4245_data *data = dev_get_drvdata(dev);
134 struct i2c_client *client = data->client;
135 s32 val;
136 int i;
137
138 mutex_lock(&data->update_lock);
139
140 if (time_after(jiffies, data->last_updated + HZ) || !data->valid) {
141
142 /* Read control registers -- 0x00 to 0x07 */
143 for (i = 0; i < ARRAY_SIZE(data->cregs); i++) {
144 val = i2c_smbus_read_byte_data(client, i);
145 if (unlikely(val < 0))
146 data->cregs[i] = 0;
147 else
148 data->cregs[i] = val;
149 }
150
151 /* Read voltage registers -- 0x10 to 0x1c */
152 for (i = 0; i < ARRAY_SIZE(data->vregs); i++) {
153 val = i2c_smbus_read_byte_data(client, i+0x10);
154 if (unlikely(val < 0))
155 data->vregs[i] = 0;
156 else
157 data->vregs[i] = val;
158 }
159
160 /* Update GPIO readings */
161 ltc4245_update_gpios(dev);
162
163 data->last_updated = jiffies;
164 data->valid = true;
165 }
166
167 mutex_unlock(&data->update_lock);
168
169 return data;
170}
171
172/* Return the voltage from the given register in millivolts */
173static int ltc4245_get_voltage(struct device *dev, u8 reg)
174{
175 struct ltc4245_data *data = ltc4245_update_device(dev);
176 const u8 regval = data->vregs[reg - 0x10];
177 u32 voltage = 0;
178
179 switch (reg) {
180 case LTC4245_12VIN:
181 case LTC4245_12VOUT:
182 voltage = regval * 55;
183 break;
184 case LTC4245_5VIN:
185 case LTC4245_5VOUT:
186 voltage = regval * 22;
187 break;
188 case LTC4245_3VIN:
189 case LTC4245_3VOUT:
190 voltage = regval * 15;
191 break;
192 case LTC4245_VEEIN:
193 case LTC4245_VEEOUT:
194 voltage = regval * -55;
195 break;
196 case LTC4245_GPIOADC:
197 voltage = regval * 10;
198 break;
199 default:
200 /* If we get here, the developer messed up */
201 WARN_ON_ONCE(1);
202 break;
203 }
204
205 return voltage;
206}
207
208/* Return the current in the given sense register in milliAmperes */
209static unsigned int ltc4245_get_current(struct device *dev, u8 reg)
210{
211 struct ltc4245_data *data = ltc4245_update_device(dev);
212 const u8 regval = data->vregs[reg - 0x10];
213 unsigned int voltage;
214 unsigned int curr;
215
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
258/* Map from voltage channel index to voltage register */
259
260static const s8 ltc4245_in_regs[] = {
261 LTC4245_12VIN, LTC4245_5VIN, LTC4245_3VIN, LTC4245_VEEIN,
262 LTC4245_12VOUT, LTC4245_5VOUT, LTC4245_3VOUT, LTC4245_VEEOUT,
263};
264
265/* Map from current channel index to current register */
266
267static const s8 ltc4245_curr_regs[] = {
268 LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE,
269};
270
271static int ltc4245_read_curr(struct device *dev, u32 attr, int channel,
272 long *val)
273{
274 struct ltc4245_data *data = ltc4245_update_device(dev);
275
276 switch (attr) {
277 case hwmon_curr_input:
278 *val = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
279 return 0;
280 case hwmon_curr_max_alarm:
281 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel + 4));
282 return 0;
283 default:
284 return -EOPNOTSUPP;
285 }
286}
287
288static int ltc4245_read_in(struct device *dev, u32 attr, int channel, long *val)
289{
290 struct ltc4245_data *data = ltc4245_update_device(dev);
291
292 switch (attr) {
293 case hwmon_in_input:
294 if (channel < 8) {
295 *val = ltc4245_get_voltage(dev,
296 ltc4245_in_regs[channel]);
297 } else {
298 int regval = data->gpios[channel - 8];
299
300 if (regval < 0)
301 return regval;
302 *val = regval * 10;
303 }
304 return 0;
305 case hwmon_in_min_alarm:
306 if (channel < 4)
307 *val = !!(data->cregs[LTC4245_FAULT1] & BIT(channel));
308 else
309 *val = !!(data->cregs[LTC4245_FAULT2] &
310 BIT(channel - 4));
311 return 0;
312 default:
313 return -EOPNOTSUPP;
314 }
315}
316
317static int ltc4245_read_power(struct device *dev, u32 attr, int channel,
318 long *val)
319{
320 unsigned long curr;
321 long voltage;
322
323 switch (attr) {
324 case hwmon_power_input:
325 (void)ltc4245_update_device(dev);
326 curr = ltc4245_get_current(dev, ltc4245_curr_regs[channel]);
327 voltage = ltc4245_get_voltage(dev, ltc4245_in_regs[channel]);
328 *val = abs(curr * voltage);
329 return 0;
330 default:
331 return -EOPNOTSUPP;
332 }
333}
334
335static int ltc4245_read(struct device *dev, enum hwmon_sensor_types type,
336 u32 attr, int channel, long *val)
337{
338
339 switch (type) {
340 case hwmon_curr:
341 return ltc4245_read_curr(dev, attr, channel, val);
342 case hwmon_power:
343 return ltc4245_read_power(dev, attr, channel, val);
344 case hwmon_in:
345 return ltc4245_read_in(dev, attr, channel - 1, val);
346 default:
347 return -EOPNOTSUPP;
348 }
349}
350
351static umode_t ltc4245_is_visible(const void *_data,
352 enum hwmon_sensor_types type,
353 u32 attr, int channel)
354{
355 const struct ltc4245_data *data = _data;
356
357 switch (type) {
358 case hwmon_in:
359 if (channel == 0)
360 return 0;
361 switch (attr) {
362 case hwmon_in_input:
363 if (channel > 9 && !data->use_extra_gpios)
364 return 0;
365 return 0444;
366 case hwmon_in_min_alarm:
367 if (channel > 8)
368 return 0;
369 return 0444;
370 default:
371 return 0;
372 }
373 case hwmon_curr:
374 switch (attr) {
375 case hwmon_curr_input:
376 case hwmon_curr_max_alarm:
377 return 0444;
378 default:
379 return 0;
380 }
381 case hwmon_power:
382 switch (attr) {
383 case hwmon_power_input:
384 return 0444;
385 default:
386 return 0;
387 }
388 default:
389 return 0;
390 }
391}
392
393static const u32 ltc4245_in_config[] = {
394 HWMON_I_INPUT, /* dummy, skipped in is_visible */
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 | HWMON_I_MIN_ALARM,
402 HWMON_I_INPUT | HWMON_I_MIN_ALARM,
403 HWMON_I_INPUT,
404 HWMON_I_INPUT,
405 HWMON_I_INPUT,
406 0
407};
408
409static const struct hwmon_channel_info ltc4245_in = {
410 .type = hwmon_in,
411 .config = ltc4245_in_config,
412};
413
414static const u32 ltc4245_curr_config[] = {
415 HWMON_C_INPUT | HWMON_C_MAX_ALARM,
416 HWMON_C_INPUT | HWMON_C_MAX_ALARM,
417 HWMON_C_INPUT | HWMON_C_MAX_ALARM,
418 HWMON_C_INPUT | HWMON_C_MAX_ALARM,
419 0
420};
421
422static const struct hwmon_channel_info ltc4245_curr = {
423 .type = hwmon_curr,
424 .config = ltc4245_curr_config,
425};
426
427static const u32 ltc4245_power_config[] = {
428 HWMON_P_INPUT,
429 HWMON_P_INPUT,
430 HWMON_P_INPUT,
431 HWMON_P_INPUT,
432 0
433};
434
435static const struct hwmon_channel_info ltc4245_power = {
436 .type = hwmon_power,
437 .config = ltc4245_power_config,
438};
439
440static const struct hwmon_channel_info *ltc4245_info[] = {
441 &ltc4245_in,
442 &ltc4245_curr,
443 &ltc4245_power,
444 NULL
445};
446
447static const struct hwmon_ops ltc4245_hwmon_ops = {
448 .is_visible = ltc4245_is_visible,
449 .read = ltc4245_read,
450};
451
452static const struct hwmon_chip_info ltc4245_chip_info = {
453 .ops = &ltc4245_hwmon_ops,
454 .info = ltc4245_info,
455};
456
457static bool ltc4245_use_extra_gpios(struct i2c_client *client)
458{
459 struct ltc4245_platform_data *pdata = dev_get_platdata(&client->dev);
460 struct device_node *np = client->dev.of_node;
461
462 /* prefer platform data */
463 if (pdata)
464 return pdata->use_extra_gpios;
465
466 /* fallback on OF */
467 if (of_find_property(np, "ltc4245,use-extra-gpios", NULL))
468 return true;
469
470 return false;
471}
472
473static int ltc4245_probe(struct i2c_client *client,
474 const struct i2c_device_id *id)
475{
476 struct i2c_adapter *adapter = client->adapter;
477 struct ltc4245_data *data;
478 struct device *hwmon_dev;
479
480 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA))
481 return -ENODEV;
482
483 data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
484 if (!data)
485 return -ENOMEM;
486
487 data->client = client;
488 mutex_init(&data->update_lock);
489 data->use_extra_gpios = ltc4245_use_extra_gpios(client);
490
491 /* Initialize the LTC4245 chip */
492 i2c_smbus_write_byte_data(client, LTC4245_FAULT1, 0x00);
493 i2c_smbus_write_byte_data(client, LTC4245_FAULT2, 0x00);
494
495 hwmon_dev = devm_hwmon_device_register_with_info(&client->dev,
496 client->name, data,
497 &ltc4245_chip_info,
498 NULL);
499 return PTR_ERR_OR_ZERO(hwmon_dev);
500}
501
502static const struct i2c_device_id ltc4245_id[] = {
503 { "ltc4245", 0 },
504 { }
505};
506MODULE_DEVICE_TABLE(i2c, ltc4245_id);
507
508/* This is the driver that will be inserted */
509static struct i2c_driver ltc4245_driver = {
510 .driver = {
511 .name = "ltc4245",
512 },
513 .probe = ltc4245_probe,
514 .id_table = ltc4245_id,
515};
516
517module_i2c_driver(ltc4245_driver);
518
519MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
520MODULE_DESCRIPTION("LTC4245 driver");
521MODULE_LICENSE("GPL");
522