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) */
26enum 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
51struct 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 */
76static 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
128static 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 */
170static 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 */
206static 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
257static 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
264static const s8 ltc4245_curr_regs[] = {
265	LTC4245_12VSENSE, LTC4245_5VSENSE, LTC4245_3VSENSE, LTC4245_VEESENSE,
266};
267
268static 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
285static 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
314static 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
332static 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
348static 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
390static 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
417static const struct hwmon_ops ltc4245_hwmon_ops = {
418	.is_visible = ltc4245_is_visible,
419	.read = ltc4245_read,
420};
421
422static const struct hwmon_chip_info ltc4245_chip_info = {
423	.ops = &ltc4245_hwmon_ops,
424	.info = ltc4245_info,
425};
426
427static 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
443static 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
471static const struct i2c_device_id ltc4245_id[] = {
472	{ "ltc4245", 0 },
473	{ }
474};
475MODULE_DEVICE_TABLE(i2c, ltc4245_id);
476
477/* This is the driver that will be inserted */
478static struct i2c_driver ltc4245_driver = {
479	.driver = {
480		.name	= "ltc4245",
481	},
482	.probe		= ltc4245_probe,
483	.id_table	= ltc4245_id,
484};
485
486module_i2c_driver(ltc4245_driver);
487
488MODULE_AUTHOR("Ira W. Snyder <iws@ovro.caltech.edu>");
489MODULE_DESCRIPTION("LTC4245 driver");
490MODULE_LICENSE("GPL");
491