1// SPDX-License-Identifier: GPL-2.0
2/*
3 * HMC425A and similar Gain Amplifiers
4 *
5 * Copyright 2020, 2024 Analog Devices Inc.
6 */
7
8#include <linux/bits.h>
9#include <linux/bitops.h>
10#include <linux/device.h>
11#include <linux/err.h>
12#include <linux/gpio/consumer.h>
13#include <linux/iio/iio.h>
14#include <linux/iio/sysfs.h>
15#include <linux/kernel.h>
16#include <linux/math.h>
17#include <linux/mod_devicetable.h>
18#include <linux/module.h>
19#include <linux/platform_device.h>
20#include <linux/property.h>
21#include <linux/slab.h>
22#include <linux/regulator/consumer.h>
23#include <linux/sysfs.h>
24
25/*
26 * The LTC6373 amplifier supports configuring gain using GPIO's with the following
27 *  values (OUTPUT_V / INPUT_V): 0(shutdown), 0.25, 0.5, 1, 2, 4, 8, 16
28 *
29 * Except for the shutdown value, all can be converted to dB using 20 * log10(x)
30 * From here, it is observed that all values are multiples of the '2' gain setting,
31 *  with the correspondent of 6.020dB.
32 */
33#define LTC6373_CONVERSION_CONSTANT	6020
34#define LTC6373_MIN_GAIN_CODE		0x6
35#define LTC6373_CONVERSION_MASK		GENMASK(2, 0)
36#define LTC6373_SHUTDOWN		GENMASK(2, 0)
37
38enum hmc425a_type {
39	ID_HMC425A,
40	ID_HMC540S,
41	ID_ADRF5740,
42	ID_LTC6373,
43};
44
45struct hmc425a_chip_info {
46	const char			*name;
47	const struct iio_chan_spec	*channels;
48	unsigned int			num_channels;
49	unsigned int			num_gpios;
50	int				gain_min;
51	int				gain_max;
52	int				default_gain;
53	int				powerdown_val;
54	bool				has_powerdown;
55
56	int				(*gain_dB_to_code)(int gain, int *code);
57	int				(*code_to_gain_dB)(int code, int *val, int *val2);
58};
59
60struct hmc425a_state {
61	struct	mutex lock; /* protect sensor state */
62	const struct	hmc425a_chip_info *chip_info;
63	struct	gpio_descs *gpios;
64	u32	gain;
65	bool	powerdown;
66};
67
68static int gain_dB_to_code(struct hmc425a_state *st, int val, int val2, int *code)
69{
70	const struct hmc425a_chip_info *inf = st->chip_info;
71	int gain;
72
73	if (val < 0)
74		gain = (val * 1000) - (val2 / 1000);
75	else
76		gain = (val * 1000) + (val2 / 1000);
77
78	if (gain > inf->gain_max || gain < inf->gain_min)
79		return -EINVAL;
80	if (st->powerdown)
81		return -EPERM;
82
83	return st->chip_info->gain_dB_to_code(gain, code);
84}
85
86static int hmc425a_gain_dB_to_code(int gain, int *code)
87{
88	*code = ~((abs(gain) / 500) & 0x3F);
89	return 0;
90}
91
92static int hmc540s_gain_dB_to_code(int gain, int *code)
93{
94	*code = ~((abs(gain) / 1000) & 0xF);
95	return 0;
96}
97
98static int adrf5740_gain_dB_to_code(int gain, int *code)
99{
100	int temp = (abs(gain) / 2000) & 0xF;
101
102	/* Bit [0-3]: 2dB 4dB 8dB 8dB */
103	*code = temp & BIT(3) ? temp | BIT(2) : temp;
104	return 0;
105}
106
107static int ltc6373_gain_dB_to_code(int gain, int *code)
108{
109	*code = ~(DIV_ROUND_CLOSEST(gain, LTC6373_CONVERSION_CONSTANT) + 3)
110		& LTC6373_CONVERSION_MASK;
111	return 0;
112}
113
114static int code_to_gain_dB(struct hmc425a_state *st, int *val, int *val2)
115{
116	if (st->powerdown)
117		return -EPERM;
118	return st->chip_info->code_to_gain_dB(st->gain, val, val2);
119}
120
121static int hmc425a_code_to_gain_dB(int code, int *val, int *val2)
122{
123	*val = (~code * -500) / 1000;
124	*val2 = ((~code * -500) % 1000) * 1000;
125	return 0;
126}
127
128static int hmc540s_code_to_gain_dB(int code, int *val, int *val2)
129{
130	*val = (~code * -1000) / 1000;
131	*val2 = ((~code * -1000) % 1000) * 1000;
132	return 0;
133}
134
135static int adrf5740_code_to_gain_dB(int code, int *val, int *val2)
136{
137	/*
138	 * Bit [0-3]: 2dB 4dB 8dB 8dB
139	 * When BIT(3) is set, unset BIT(2) and use 3 as double the place value
140	 */
141	code = code & BIT(3) ? code & ~BIT(2) : code;
142	*val = (code * -2000) / 1000;
143	*val2 = ((code * -2000) % 1000) * 1000;
144	return 0;
145}
146
147static int ltc6373_code_to_gain_dB(int code, int *val, int *val2)
148{
149	int gain = ((~code & LTC6373_CONVERSION_MASK) - 3) *
150		   LTC6373_CONVERSION_CONSTANT;
151
152	*val = gain / 1000;
153	*val2 = (gain % 1000) * 1000;
154	return 0;
155}
156
157static int hmc425a_write(struct iio_dev *indio_dev, u32 value)
158{
159	struct hmc425a_state *st = iio_priv(indio_dev);
160	DECLARE_BITMAP(values, BITS_PER_TYPE(value));
161
162	values[0] = value;
163
164	gpiod_set_array_value_cansleep(st->gpios->ndescs, st->gpios->desc,
165				       NULL, values);
166	return 0;
167}
168
169static int hmc425a_read_raw(struct iio_dev *indio_dev,
170			    struct iio_chan_spec const *chan, int *val,
171			    int *val2, long m)
172{
173	struct hmc425a_state *st = iio_priv(indio_dev);
174	int ret;
175
176	mutex_lock(&st->lock);
177	switch (m) {
178	case IIO_CHAN_INFO_HARDWAREGAIN:
179		ret = code_to_gain_dB(st, val, val2);
180		if (ret)
181			break;
182		ret = IIO_VAL_INT_PLUS_MICRO_DB;
183		break;
184	default:
185		ret = -EINVAL;
186	}
187	mutex_unlock(&st->lock);
188
189	return ret;
190};
191
192static int hmc425a_write_raw(struct iio_dev *indio_dev,
193			     struct iio_chan_spec const *chan, int val,
194			     int val2, long mask)
195{
196	struct hmc425a_state *st = iio_priv(indio_dev);
197	int code = 0, ret;
198
199	mutex_lock(&st->lock);
200	switch (mask) {
201	case IIO_CHAN_INFO_HARDWAREGAIN:
202		ret = gain_dB_to_code(st, val, val2, &code);
203		if (ret)
204			break;
205		st->gain = code;
206
207		ret = hmc425a_write(indio_dev, st->gain);
208		break;
209	default:
210		ret = -EINVAL;
211	}
212	mutex_unlock(&st->lock);
213
214	return ret;
215}
216
217static int hmc425a_write_raw_get_fmt(struct iio_dev *indio_dev,
218				     struct iio_chan_spec const *chan,
219				     long mask)
220{
221	switch (mask) {
222	case IIO_CHAN_INFO_HARDWAREGAIN:
223		return IIO_VAL_INT_PLUS_MICRO_DB;
224	default:
225		return -EINVAL;
226	}
227}
228
229static const struct iio_info hmc425a_info = {
230	.read_raw = &hmc425a_read_raw,
231	.write_raw = &hmc425a_write_raw,
232	.write_raw_get_fmt = &hmc425a_write_raw_get_fmt,
233};
234
235static ssize_t ltc6373_read_powerdown(struct iio_dev *indio_dev,
236				      uintptr_t private,
237				      const struct iio_chan_spec *chan,
238				      char *buf)
239{
240	struct hmc425a_state *st = iio_priv(indio_dev);
241
242	return sysfs_emit(buf, "%d\n", st->powerdown);
243}
244
245static ssize_t ltc6373_write_powerdown(struct iio_dev *indio_dev,
246				       uintptr_t private,
247				       const struct iio_chan_spec *chan,
248				       const char *buf,
249				       size_t len)
250{
251	struct hmc425a_state *st = iio_priv(indio_dev);
252	bool powerdown;
253	int code, ret;
254
255	ret = kstrtobool(buf, &powerdown);
256	if (ret)
257		return ret;
258
259	mutex_lock(&st->lock);
260	st->powerdown = powerdown;
261	code = (powerdown) ? LTC6373_SHUTDOWN : st->gain;
262	hmc425a_write(indio_dev, code);
263	mutex_unlock(&st->lock);
264	return len;
265}
266
267static const struct iio_chan_spec_ext_info ltc6373_ext_info[] = {
268	{
269		.name = "powerdown",
270		.read = ltc6373_read_powerdown,
271		.write = ltc6373_write_powerdown,
272		.shared = IIO_SEPARATE,
273	},
274	{}
275};
276
277#define HMC425A_CHAN(_channel)						\
278{									\
279	.type = IIO_VOLTAGE,						\
280	.output = 1,							\
281	.indexed = 1,							\
282	.channel = _channel,						\
283	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),		\
284}
285
286#define LTC6373_CHAN(_channel)						\
287{									\
288	.type = IIO_VOLTAGE,						\
289	.output = 1,							\
290	.indexed = 1,							\
291	.channel = _channel,						\
292	.info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN),		\
293	.ext_info = ltc6373_ext_info,					\
294}
295
296static const struct iio_chan_spec hmc425a_channels[] = {
297	HMC425A_CHAN(0),
298};
299
300static const struct iio_chan_spec ltc6373_channels[] = {
301	LTC6373_CHAN(0),
302};
303
304static const struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
305	[ID_HMC425A] = {
306		.name = "hmc425a",
307		.channels = hmc425a_channels,
308		.num_channels = ARRAY_SIZE(hmc425a_channels),
309		.num_gpios = 6,
310		.gain_min = -31500,
311		.gain_max = 0,
312		.default_gain = -0x40, /* set default gain -31.5db*/
313		.gain_dB_to_code = hmc425a_gain_dB_to_code,
314		.code_to_gain_dB = hmc425a_code_to_gain_dB,
315	},
316	[ID_HMC540S] = {
317		.name = "hmc540s",
318		.channels = hmc425a_channels,
319		.num_channels = ARRAY_SIZE(hmc425a_channels),
320		.num_gpios = 4,
321		.gain_min = -15000,
322		.gain_max = 0,
323		.default_gain = -0x10, /* set default gain -15.0db*/
324		.gain_dB_to_code = hmc540s_gain_dB_to_code,
325		.code_to_gain_dB = hmc540s_code_to_gain_dB,
326	},
327	[ID_ADRF5740] = {
328		.name = "adrf5740",
329		.channels = hmc425a_channels,
330		.num_channels = ARRAY_SIZE(hmc425a_channels),
331		.num_gpios = 4,
332		.gain_min = -22000,
333		.gain_max = 0,
334		.default_gain = 0xF, /* set default gain -22.0db*/
335		.gain_dB_to_code = adrf5740_gain_dB_to_code,
336		.code_to_gain_dB = adrf5740_code_to_gain_dB,
337	},
338	[ID_LTC6373] = {
339		.name = "ltc6373",
340		.channels = ltc6373_channels,
341		.num_channels = ARRAY_SIZE(ltc6373_channels),
342		.num_gpios = 3,
343		.gain_min = -12041, /* gain setting x0.25*/
344		.gain_max = 24082,  /* gain setting x16  */
345		.default_gain = LTC6373_MIN_GAIN_CODE,
346		.powerdown_val = LTC6373_SHUTDOWN,
347		.has_powerdown = true,
348		.gain_dB_to_code = ltc6373_gain_dB_to_code,
349		.code_to_gain_dB = ltc6373_code_to_gain_dB,
350	},
351};
352
353static int hmc425a_probe(struct platform_device *pdev)
354{
355	struct iio_dev *indio_dev;
356	struct hmc425a_state *st;
357	int ret;
358
359	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
360	if (!indio_dev)
361		return -ENOMEM;
362
363	st = iio_priv(indio_dev);
364
365	st->chip_info = device_get_match_data(&pdev->dev);
366	indio_dev->num_channels = st->chip_info->num_channels;
367	indio_dev->channels = st->chip_info->channels;
368	indio_dev->name = st->chip_info->name;
369	st->gain = st->chip_info->default_gain;
370
371	st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl", GPIOD_OUT_LOW);
372	if (IS_ERR(st->gpios))
373		return dev_err_probe(&pdev->dev, PTR_ERR(st->gpios),
374				     "failed to get gpios\n");
375
376	if (st->gpios->ndescs != st->chip_info->num_gpios) {
377		dev_err(&pdev->dev, "%d GPIOs needed to operate\n",
378			st->chip_info->num_gpios);
379		return -ENODEV;
380	}
381
382	ret = devm_regulator_get_enable(&pdev->dev, "vcc-supply");
383	if (ret)
384		return ret;
385
386	mutex_init(&st->lock);
387
388	indio_dev->info = &hmc425a_info;
389	indio_dev->modes = INDIO_DIRECT_MODE;
390
391	if (st->chip_info->has_powerdown) {
392		st->powerdown = true;
393		hmc425a_write(indio_dev, st->chip_info->powerdown_val);
394	} else {
395		/* Set default gain */
396		hmc425a_write(indio_dev, st->gain);
397	}
398
399	return devm_iio_device_register(&pdev->dev, indio_dev);
400}
401
402/* Match table for of_platform binding */
403static const struct of_device_id hmc425a_of_match[] = {
404	{ .compatible = "adi,hmc425a",
405	  .data = &hmc425a_chip_info_tbl[ID_HMC425A]},
406	{ .compatible = "adi,hmc540s",
407	  .data = &hmc425a_chip_info_tbl[ID_HMC540S]},
408	{ .compatible = "adi,adrf5740",
409	  .data = &hmc425a_chip_info_tbl[ID_ADRF5740]},
410	{ .compatible = "adi,ltc6373",
411	  .data = &hmc425a_chip_info_tbl[ID_LTC6373]},
412	{}
413};
414MODULE_DEVICE_TABLE(of, hmc425a_of_match);
415
416static struct platform_driver hmc425a_driver = {
417	.driver = {
418		.name = KBUILD_MODNAME,
419		.of_match_table = hmc425a_of_match,
420	},
421	.probe = hmc425a_probe,
422};
423module_platform_driver(hmc425a_driver);
424
425MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
426MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO control Gain Amplifiers");
427MODULE_LICENSE("GPL v2");
428