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_multi_set_value_cansleep(st->gpios, values);
165 return 0;
166 }
167
hmc425a_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long m)168 static int hmc425a_read_raw(struct iio_dev *indio_dev,
169 struct iio_chan_spec const *chan, int *val,
170 int *val2, long m)
171 {
172 struct hmc425a_state *st = iio_priv(indio_dev);
173 int ret;
174
175 mutex_lock(&st->lock);
176 switch (m) {
177 case IIO_CHAN_INFO_HARDWAREGAIN:
178 ret = code_to_gain_dB(st, val, val2);
179 if (ret)
180 break;
181 ret = IIO_VAL_INT_PLUS_MICRO_DB;
182 break;
183 default:
184 ret = -EINVAL;
185 }
186 mutex_unlock(&st->lock);
187
188 return ret;
189 };
190
hmc425a_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)191 static int hmc425a_write_raw(struct iio_dev *indio_dev,
192 struct iio_chan_spec const *chan, int val,
193 int val2, long mask)
194 {
195 struct hmc425a_state *st = iio_priv(indio_dev);
196 int code = 0, ret;
197
198 mutex_lock(&st->lock);
199 switch (mask) {
200 case IIO_CHAN_INFO_HARDWAREGAIN:
201 ret = gain_dB_to_code(st, val, val2, &code);
202 if (ret)
203 break;
204 st->gain = code;
205
206 ret = hmc425a_write(indio_dev, st->gain);
207 break;
208 default:
209 ret = -EINVAL;
210 }
211 mutex_unlock(&st->lock);
212
213 return ret;
214 }
215
hmc425a_write_raw_get_fmt(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,long mask)216 static int hmc425a_write_raw_get_fmt(struct iio_dev *indio_dev,
217 struct iio_chan_spec const *chan,
218 long mask)
219 {
220 switch (mask) {
221 case IIO_CHAN_INFO_HARDWAREGAIN:
222 return IIO_VAL_INT_PLUS_MICRO_DB;
223 default:
224 return -EINVAL;
225 }
226 }
227
228 static const struct iio_info hmc425a_info = {
229 .read_raw = &hmc425a_read_raw,
230 .write_raw = &hmc425a_write_raw,
231 .write_raw_get_fmt = &hmc425a_write_raw_get_fmt,
232 };
233
ltc6373_read_powerdown(struct iio_dev * indio_dev,uintptr_t private,const struct iio_chan_spec * chan,char * buf)234 static ssize_t ltc6373_read_powerdown(struct iio_dev *indio_dev,
235 uintptr_t private,
236 const struct iio_chan_spec *chan,
237 char *buf)
238 {
239 struct hmc425a_state *st = iio_priv(indio_dev);
240
241 return sysfs_emit(buf, "%d\n", st->powerdown);
242 }
243
ltc6373_write_powerdown(struct iio_dev * indio_dev,uintptr_t private,const struct iio_chan_spec * chan,const char * buf,size_t len)244 static ssize_t ltc6373_write_powerdown(struct iio_dev *indio_dev,
245 uintptr_t private,
246 const struct iio_chan_spec *chan,
247 const char *buf,
248 size_t len)
249 {
250 struct hmc425a_state *st = iio_priv(indio_dev);
251 bool powerdown;
252 int code, ret;
253
254 ret = kstrtobool(buf, &powerdown);
255 if (ret)
256 return ret;
257
258 mutex_lock(&st->lock);
259 st->powerdown = powerdown;
260 code = (powerdown) ? LTC6373_SHUTDOWN : st->gain;
261 hmc425a_write(indio_dev, code);
262 mutex_unlock(&st->lock);
263 return len;
264 }
265
266 static const struct iio_chan_spec_ext_info ltc6373_ext_info[] = {
267 {
268 .name = "powerdown",
269 .read = ltc6373_read_powerdown,
270 .write = ltc6373_write_powerdown,
271 .shared = IIO_SEPARATE,
272 },
273 { }
274 };
275
276 #define HMC425A_CHAN(_channel) \
277 { \
278 .type = IIO_VOLTAGE, \
279 .output = 1, \
280 .indexed = 1, \
281 .channel = _channel, \
282 .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
283 }
284
285 #define LTC6373_CHAN(_channel) \
286 { \
287 .type = IIO_VOLTAGE, \
288 .output = 1, \
289 .indexed = 1, \
290 .channel = _channel, \
291 .info_mask_separate = BIT(IIO_CHAN_INFO_HARDWAREGAIN), \
292 .ext_info = ltc6373_ext_info, \
293 }
294
295 static const struct iio_chan_spec hmc425a_channels[] = {
296 HMC425A_CHAN(0),
297 };
298
299 static const struct iio_chan_spec ltc6373_channels[] = {
300 LTC6373_CHAN(0),
301 };
302
303 static const struct hmc425a_chip_info hmc425a_chip_info_tbl[] = {
304 [ID_HMC425A] = {
305 .name = "hmc425a",
306 .channels = hmc425a_channels,
307 .num_channels = ARRAY_SIZE(hmc425a_channels),
308 .num_gpios = 6,
309 .gain_min = -31500,
310 .gain_max = 0,
311 .default_gain = -0x40, /* set default gain -31.5db*/
312 .gain_dB_to_code = hmc425a_gain_dB_to_code,
313 .code_to_gain_dB = hmc425a_code_to_gain_dB,
314 },
315 [ID_HMC540S] = {
316 .name = "hmc540s",
317 .channels = hmc425a_channels,
318 .num_channels = ARRAY_SIZE(hmc425a_channels),
319 .num_gpios = 4,
320 .gain_min = -15000,
321 .gain_max = 0,
322 .default_gain = -0x10, /* set default gain -15.0db*/
323 .gain_dB_to_code = hmc540s_gain_dB_to_code,
324 .code_to_gain_dB = hmc540s_code_to_gain_dB,
325 },
326 [ID_ADRF5740] = {
327 .name = "adrf5740",
328 .channels = hmc425a_channels,
329 .num_channels = ARRAY_SIZE(hmc425a_channels),
330 .num_gpios = 4,
331 .gain_min = -22000,
332 .gain_max = 0,
333 .default_gain = 0xF, /* set default gain -22.0db*/
334 .gain_dB_to_code = adrf5740_gain_dB_to_code,
335 .code_to_gain_dB = adrf5740_code_to_gain_dB,
336 },
337 [ID_LTC6373] = {
338 .name = "ltc6373",
339 .channels = ltc6373_channels,
340 .num_channels = ARRAY_SIZE(ltc6373_channels),
341 .num_gpios = 3,
342 .gain_min = -12041, /* gain setting x0.25*/
343 .gain_max = 24082, /* gain setting x16 */
344 .default_gain = LTC6373_MIN_GAIN_CODE,
345 .powerdown_val = LTC6373_SHUTDOWN,
346 .has_powerdown = true,
347 .gain_dB_to_code = ltc6373_gain_dB_to_code,
348 .code_to_gain_dB = ltc6373_code_to_gain_dB,
349 },
350 };
351
hmc425a_probe(struct platform_device * pdev)352 static int hmc425a_probe(struct platform_device *pdev)
353 {
354 struct iio_dev *indio_dev;
355 struct hmc425a_state *st;
356 int ret;
357
358 indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*st));
359 if (!indio_dev)
360 return -ENOMEM;
361
362 st = iio_priv(indio_dev);
363
364 st->chip_info = device_get_match_data(&pdev->dev);
365 indio_dev->num_channels = st->chip_info->num_channels;
366 indio_dev->channels = st->chip_info->channels;
367 indio_dev->name = st->chip_info->name;
368 st->gain = st->chip_info->default_gain;
369
370 st->gpios = devm_gpiod_get_array(&pdev->dev, "ctrl", GPIOD_OUT_LOW);
371 if (IS_ERR(st->gpios))
372 return dev_err_probe(&pdev->dev, PTR_ERR(st->gpios),
373 "failed to get gpios\n");
374
375 if (st->gpios->ndescs != st->chip_info->num_gpios) {
376 dev_err(&pdev->dev, "%d GPIOs needed to operate\n",
377 st->chip_info->num_gpios);
378 return -ENODEV;
379 }
380
381 ret = devm_regulator_get_enable(&pdev->dev, "vcc-supply");
382 if (ret)
383 return ret;
384
385 mutex_init(&st->lock);
386
387 indio_dev->info = &hmc425a_info;
388 indio_dev->modes = INDIO_DIRECT_MODE;
389
390 if (st->chip_info->has_powerdown) {
391 st->powerdown = true;
392 hmc425a_write(indio_dev, st->chip_info->powerdown_val);
393 } else {
394 /* Set default gain */
395 hmc425a_write(indio_dev, st->gain);
396 }
397
398 return devm_iio_device_register(&pdev->dev, indio_dev);
399 }
400
401 static const struct of_device_id hmc425a_of_match[] = {
402 { .compatible = "adi,hmc425a",
403 .data = &hmc425a_chip_info_tbl[ID_HMC425A]},
404 { .compatible = "adi,hmc540s",
405 .data = &hmc425a_chip_info_tbl[ID_HMC540S]},
406 { .compatible = "adi,adrf5740",
407 .data = &hmc425a_chip_info_tbl[ID_ADRF5740]},
408 { .compatible = "adi,ltc6373",
409 .data = &hmc425a_chip_info_tbl[ID_LTC6373]},
410 { }
411 };
412 MODULE_DEVICE_TABLE(of, hmc425a_of_match);
413
414 static struct platform_driver hmc425a_driver = {
415 .driver = {
416 .name = KBUILD_MODNAME,
417 .of_match_table = hmc425a_of_match,
418 },
419 .probe = hmc425a_probe,
420 };
421 module_platform_driver(hmc425a_driver);
422
423 MODULE_AUTHOR("Michael Hennerich <michael.hennerich@analog.com>");
424 MODULE_DESCRIPTION("Analog Devices HMC425A and similar GPIO control Gain Amplifiers");
425 MODULE_LICENSE("GPL v2");
426