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
38 enum hmc425a_type {
39 ID_HMC425A,
40 ID_HMC540S,
41 ID_ADRF5740,
42 ID_LTC6373,
43 };
44
45 struct 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
60 struct 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
gain_dB_to_code(struct hmc425a_state * st,int val,int val2,int * code)68 static 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
hmc425a_gain_dB_to_code(int gain,int * code)86 static int hmc425a_gain_dB_to_code(int gain, int *code)
87 {
88 *code = ~((abs(gain) / 500) & 0x3F);
89 return 0;
90 }
91
hmc540s_gain_dB_to_code(int gain,int * code)92 static int hmc540s_gain_dB_to_code(int gain, int *code)
93 {
94 *code = ~((abs(gain) / 1000) & 0xF);
95 return 0;
96 }
97
adrf5740_gain_dB_to_code(int gain,int * code)98 static 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
ltc6373_gain_dB_to_code(int gain,int * code)107 static 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
code_to_gain_dB(struct hmc425a_state * st,int * val,int * val2)114 static 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
hmc425a_code_to_gain_dB(int code,int * val,int * val2)121 static 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
hmc540s_code_to_gain_dB(int code,int * val,int * val2)128 static 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
adrf5740_code_to_gain_dB(int code,int * val,int * val2)135 static 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
ltc6373_code_to_gain_dB(int code,int * val,int * val2)147 static 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
hmc425a_write(struct iio_dev * indio_dev,u32 value)157 static 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
hmc425a_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)169 static 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
hmc425a_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)192 static 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
hmc425a_write_raw_get_fmt(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,long mask)217 static 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
229 static 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
ltc6373_read_powerdown(struct iio_dev * indio_dev,uintptr_t private,const struct iio_chan_spec * chan,char * buf)235 static 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
ltc6373_write_powerdown(struct iio_dev * indio_dev,uintptr_t private,const struct iio_chan_spec * chan,const char * buf,size_t len)245 static 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
267 static 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
296 static const struct iio_chan_spec hmc425a_channels[] = {
297 HMC425A_CHAN(0),
298 };
299
300 static const struct iio_chan_spec ltc6373_channels[] = {
301 LTC6373_CHAN(0),
302 };
303
304 static 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
hmc425a_probe(struct platform_device * pdev)353 static 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 */
403 static 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 };
414 MODULE_DEVICE_TABLE(of, hmc425a_of_match);
415
416 static struct platform_driver hmc425a_driver = {
417 .driver = {
418 .name = KBUILD_MODNAME,
419 .of_match_table = hmc425a_of_match,
420 },
421 .probe = hmc425a_probe,
422 };
423 module_platform_driver(hmc425a_driver);
424
425 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
426 MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO control Gain Amplifiers");
427 MODULE_LICENSE("GPL v2");
428