mcp4728.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Support for Microchip MCP4728
  4 *
  5 * Copyright (C) 2023 Andrea Collamati <andrea.collamati@gmail.com>
  6 *
  7 * Based on mcp4725 by Peter Meerwald <pmeerw@pmeerw.net>
  8 *
  9 * Driver for the Microchip I2C 12-bit digital-to-analog quad channels
 10 * converter (DAC).
 11 *
 12 * (7-bit I2C slave address 0x60, the three LSBs can be configured in
 13 * hardware)
 14 */
 15
 16#include <linux/bitfield.h>
 17#include <linux/delay.h>
 18#include <linux/err.h>
 19#include <linux/i2c.h>
 20#include <linux/iio/iio.h>
 21#include <linux/iio/sysfs.h>
 22#include <linux/module.h>
 23#include <linux/mod_devicetable.h>
 24#include <linux/property.h>
 25#include <linux/regulator/consumer.h>
 26
 27#define MCP4728_RESOLUTION	  12
 28#define MCP4728_N_CHANNELS	  4
 29
 30#define MCP4728_CMD_MASK	  GENMASK(7, 3)
 31#define MCP4728_CHSEL_MASK	  GENMASK(2, 1)
 32#define MCP4728_UDAC_MASK	  BIT(0)
 33
 34#define MCP4728_VREF_MASK	  BIT(7)
 35#define MCP4728_PDMODE_MASK	  GENMASK(6, 5)
 36#define MCP4728_GAIN_MASK	  BIT(4)
 37
 38#define MCP4728_DAC_H_MASK	  GENMASK(3, 0)
 39#define MCP4728_DAC_L_MASK	  GENMASK(7, 0)
 40
 41#define MCP4728_RDY_MASK	  BIT(7)
 42
 43#define MCP4728_MW_CMD		  0x08 /* Multiwrite Command */
 44#define MCP4728_SW_CMD		  0x0A /* Sequential Write Command with EEPROM */
 45
 46#define MCP4728_READ_RESPONSE_LEN (MCP4728_N_CHANNELS * 3 * 2)
 47#define MCP4728_WRITE_EEPROM_LEN  (1 + MCP4728_N_CHANNELS * 2)
 48
 49enum vref_mode {
 50	MCP4728_VREF_EXTERNAL_VDD    = 0,
 51	MCP4728_VREF_INTERNAL_2048mV = 1,
 52};
 53
 54enum gain_mode {
 55	MCP4728_GAIN_X1 = 0,
 56	MCP4728_GAIN_X2 = 1,
 57};
 58
 59enum iio_powerdown_mode {
 60	MCP4728_IIO_1K,
 61	MCP4728_IIO_100K,
 62	MCP4728_IIO_500K,
 63};
 64
 65struct mcp4728_channel_data {
 66	enum vref_mode ref_mode;
 67	enum iio_powerdown_mode pd_mode;
 68	enum gain_mode g_mode;
 69	u16 dac_value;
 70};
 71
 72/* MCP4728 Full Scale Ranges
 73 * the device available ranges are
 74 * - VREF = VDD				FSR = from 0.0V to VDD
 75 * - VREF = Internal	Gain = 1	FSR = from 0.0V to VREF
 76 * - VREF = Internal	Gain = 2	FSR = from 0.0V to 2*VREF
 77 */
 78enum mcp4728_scale {
 79	MCP4728_SCALE_VDD,
 80	MCP4728_SCALE_VINT_NO_GAIN,
 81	MCP4728_SCALE_VINT_GAIN_X2,
 82	MCP4728_N_SCALES
 83};
 84
 85struct mcp4728_data {
 86	struct i2c_client *client;
 87	bool powerdown;
 88	int scales_avail[MCP4728_N_SCALES * 2];
 89	struct mcp4728_channel_data chdata[MCP4728_N_CHANNELS];
 90};
 91
 92#define MCP4728_CHAN(chan) {						\
 93	.type = IIO_VOLTAGE,						\
 94	.output = 1,							\
 95	.indexed = 1,							\
 96	.channel = chan,						\
 97	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW)	|		\
 98			      BIT(IIO_CHAN_INFO_SCALE),			\
 99	.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),	\
100	.ext_info = mcp4728_ext_info,					\
101}
102
103static int mcp4728_suspend(struct device *dev);
104static int mcp4728_resume(struct device *dev);
105
106static ssize_t mcp4728_store_eeprom(struct device *dev,
107				    struct device_attribute *attr,
108				    const char *buf, size_t len)
109{
110	struct iio_dev *indio_dev = dev_to_iio_dev(dev);
111	struct mcp4728_data *data = iio_priv(indio_dev);
112	u8 outbuf[MCP4728_WRITE_EEPROM_LEN];
113	int tries = 20;
114	u8 inbuf[3];
115	bool state;
116	int ret;
117	unsigned int i;
118
119	ret = kstrtobool(buf, &state);
120	if (ret < 0)
121		return ret;
122
123	if (!state)
124		return 0;
125
126	outbuf[0] = FIELD_PREP(MCP4728_CMD_MASK, MCP4728_SW_CMD);
127
128	for (i = 0; i < MCP4728_N_CHANNELS; i++) {
129		struct mcp4728_channel_data *ch = &data->chdata[i];
130		int offset			= 1 + i * 2;
131
132		outbuf[offset] = FIELD_PREP(MCP4728_VREF_MASK, ch->ref_mode);
133
134		if (data->powerdown) {
135			u8 mcp4728_pd_mode = ch->pd_mode + 1;
136
137			outbuf[offset] |= FIELD_PREP(MCP4728_PDMODE_MASK,
138						     mcp4728_pd_mode);
139		}
140
141		outbuf[offset] |= FIELD_PREP(MCP4728_GAIN_MASK, ch->g_mode);
142		outbuf[offset] |=
143			FIELD_PREP(MCP4728_DAC_H_MASK, ch->dac_value >> 8);
144		outbuf[offset + 1] =
145			FIELD_PREP(MCP4728_DAC_L_MASK, ch->dac_value);
146	}
147
148	ret = i2c_master_send(data->client, outbuf, MCP4728_WRITE_EEPROM_LEN);
149	if (ret < 0)
150		return ret;
151	else if (ret != MCP4728_WRITE_EEPROM_LEN)
152		return -EIO;
153
154	/* wait RDY signal for write complete, takes up to 50ms */
155	while (tries--) {
156		msleep(20);
157		ret = i2c_master_recv(data->client, inbuf, 3);
158		if (ret < 0)
159			return ret;
160		else if (ret != 3)
161			return -EIO;
162
163		if (FIELD_GET(MCP4728_RDY_MASK, inbuf[0]))
164			break;
165	}
166
167	if (tries < 0) {
168		dev_err(&data->client->dev, "%s failed, incomplete\n",
169			__func__);
170		return -EIO;
171	}
172	return len;
173}
174
175static IIO_DEVICE_ATTR(store_eeprom, 0200, NULL, mcp4728_store_eeprom, 0);
176
177static struct attribute *mcp4728_attributes[] = {
178	&iio_dev_attr_store_eeprom.dev_attr.attr,
179	NULL,
180};
181
182static const struct attribute_group mcp4728_attribute_group = {
183	.attrs = mcp4728_attributes,
184};
185
186static int mcp4728_program_channel_cfg(int channel, struct iio_dev *indio_dev)
187{
188	struct mcp4728_data *data	= iio_priv(indio_dev);
189	struct mcp4728_channel_data *ch = &data->chdata[channel];
190	u8 outbuf[3];
191	int ret;
192
193	outbuf[0] = FIELD_PREP(MCP4728_CMD_MASK, MCP4728_MW_CMD);
194	outbuf[0] |= FIELD_PREP(MCP4728_CHSEL_MASK, channel);
195	outbuf[0] |= FIELD_PREP(MCP4728_UDAC_MASK, 0);
196
197	outbuf[1] = FIELD_PREP(MCP4728_VREF_MASK, ch->ref_mode);
198
199	if (data->powerdown)
200		outbuf[1] |= FIELD_PREP(MCP4728_PDMODE_MASK, ch->pd_mode + 1);
201
202	outbuf[1] |= FIELD_PREP(MCP4728_GAIN_MASK, ch->g_mode);
203	outbuf[1] |= FIELD_PREP(MCP4728_DAC_H_MASK, ch->dac_value >> 8);
204	outbuf[2] = FIELD_PREP(MCP4728_DAC_L_MASK, ch->dac_value);
205
206	ret = i2c_master_send(data->client, outbuf, 3);
207	if (ret < 0)
208		return ret;
209	else if (ret != 3)
210		return -EIO;
211
212	return 0;
213}
214
215static const char *const mcp4728_powerdown_modes[] = { "1kohm_to_gnd",
216						       "100kohm_to_gnd",
217						       "500kohm_to_gnd" };
218
219static int mcp4728_get_powerdown_mode(struct iio_dev *indio_dev,
220				      const struct iio_chan_spec *chan)
221{
222	struct mcp4728_data *data = iio_priv(indio_dev);
223
224	return data->chdata[chan->channel].pd_mode;
225}
226
227static int mcp4728_set_powerdown_mode(struct iio_dev *indio_dev,
228				      const struct iio_chan_spec *chan,
229				      unsigned int mode)
230{
231	struct mcp4728_data *data = iio_priv(indio_dev);
232
233	data->chdata[chan->channel].pd_mode = mode;
234
235	return 0;
236}
237
238static ssize_t mcp4728_read_powerdown(struct iio_dev *indio_dev,
239				      uintptr_t private,
240				      const struct iio_chan_spec *chan,
241				      char *buf)
242{
243	struct mcp4728_data *data = iio_priv(indio_dev);
244
245	return sysfs_emit(buf, "%d\n", data->powerdown);
246}
247
248static ssize_t mcp4728_write_powerdown(struct iio_dev *indio_dev,
249				       uintptr_t private,
250				       const struct iio_chan_spec *chan,
251				       const char *buf, size_t len)
252{
253	struct mcp4728_data *data = iio_priv(indio_dev);
254	bool state;
255	int ret;
256
257	ret = kstrtobool(buf, &state);
258	if (ret)
259		return ret;
260
261	if (state)
262		ret = mcp4728_suspend(&data->client->dev);
263	else
264		ret = mcp4728_resume(&data->client->dev);
265
266	if (ret < 0)
267		return ret;
268
269	return len;
270}
271
272static const struct iio_enum mcp4728_powerdown_mode_enum = {
273	.items	   = mcp4728_powerdown_modes,
274	.num_items = ARRAY_SIZE(mcp4728_powerdown_modes),
275	.get	   = mcp4728_get_powerdown_mode,
276	.set	   = mcp4728_set_powerdown_mode,
277};
278
279static const struct iio_chan_spec_ext_info mcp4728_ext_info[] = {
280	{
281		.name	= "powerdown",
282		.read	= mcp4728_read_powerdown,
283		.write	= mcp4728_write_powerdown,
284		.shared = IIO_SEPARATE,
285	},
286	IIO_ENUM("powerdown_mode", IIO_SEPARATE, &mcp4728_powerdown_mode_enum),
287	IIO_ENUM_AVAILABLE("powerdown_mode", IIO_SHARED_BY_TYPE,
288			   &mcp4728_powerdown_mode_enum),
289	{ }
290};
291
292static const struct iio_chan_spec mcp4728_channels[MCP4728_N_CHANNELS] = {
293	MCP4728_CHAN(0),
294	MCP4728_CHAN(1),
295	MCP4728_CHAN(2),
296	MCP4728_CHAN(3),
297};
298
299static void mcp4728_get_scale_avail(enum mcp4728_scale scale,
300				    struct mcp4728_data *data, int *val,
301				    int *val2)
302{
303	*val  = data->scales_avail[scale * 2];
304	*val2 = data->scales_avail[scale * 2 + 1];
305}
306
307static void mcp4728_get_scale(int channel, struct mcp4728_data *data, int *val,
308			      int *val2)
309{
310	int ref_mode = data->chdata[channel].ref_mode;
311	int g_mode   = data->chdata[channel].g_mode;
312
313	if (ref_mode == MCP4728_VREF_EXTERNAL_VDD) {
314		mcp4728_get_scale_avail(MCP4728_SCALE_VDD, data, val, val2);
315	} else {
316		if (g_mode == MCP4728_GAIN_X1) {
317			mcp4728_get_scale_avail(MCP4728_SCALE_VINT_NO_GAIN,
318						data, val, val2);
319		} else {
320			mcp4728_get_scale_avail(MCP4728_SCALE_VINT_GAIN_X2,
321						data, val, val2);
322		}
323	}
324}
325
326static int mcp4728_find_matching_scale(struct mcp4728_data *data, int val,
327				       int val2)
328{
329	for (int i = 0; i < MCP4728_N_SCALES; i++) {
330		if (data->scales_avail[i * 2] == val &&
331		    data->scales_avail[i * 2 + 1] == val2)
332			return i;
333	}
334	return -EINVAL;
335}
336
337static int mcp4728_set_scale(int channel, struct mcp4728_data *data, int val,
338			     int val2)
339{
340	int scale = mcp4728_find_matching_scale(data, val, val2);
341
342	if (scale < 0)
343		return scale;
344
345	switch (scale) {
346	case MCP4728_SCALE_VDD:
347		data->chdata[channel].ref_mode = MCP4728_VREF_EXTERNAL_VDD;
348		return 0;
349	case MCP4728_SCALE_VINT_NO_GAIN:
350		data->chdata[channel].ref_mode = MCP4728_VREF_INTERNAL_2048mV;
351		data->chdata[channel].g_mode   = MCP4728_GAIN_X1;
352		return 0;
353	case MCP4728_SCALE_VINT_GAIN_X2:
354		data->chdata[channel].ref_mode = MCP4728_VREF_INTERNAL_2048mV;
355		data->chdata[channel].g_mode   = MCP4728_GAIN_X2;
356		return 0;
357	default:
358		return -EINVAL;
359	}
360}
361
362static int mcp4728_read_raw(struct iio_dev *indio_dev,
363			    struct iio_chan_spec const *chan, int *val,
364			    int *val2, long mask)
365{
366	struct mcp4728_data *data = iio_priv(indio_dev);
367
368	switch (mask) {
369	case IIO_CHAN_INFO_RAW:
370		*val = data->chdata[chan->channel].dac_value;
371		return IIO_VAL_INT;
372	case IIO_CHAN_INFO_SCALE:
373		mcp4728_get_scale(chan->channel, data, val, val2);
374		return IIO_VAL_INT_PLUS_MICRO;
375	}
376	return -EINVAL;
377}
378
379static int mcp4728_write_raw(struct iio_dev *indio_dev,
380			     struct iio_chan_spec const *chan, int val,
381			     int val2, long mask)
382{
383	struct mcp4728_data *data = iio_priv(indio_dev);
384	int ret;
385
386	switch (mask) {
387	case IIO_CHAN_INFO_RAW:
388		if (val < 0 || val > GENMASK(MCP4728_RESOLUTION - 1, 0))
389			return -EINVAL;
390		data->chdata[chan->channel].dac_value = val;
391		return mcp4728_program_channel_cfg(chan->channel, indio_dev);
392	case IIO_CHAN_INFO_SCALE:
393		ret = mcp4728_set_scale(chan->channel, data, val, val2);
394		if (ret)
395			return ret;
396
397		return mcp4728_program_channel_cfg(chan->channel, indio_dev);
398	default:
399		return -EINVAL;
400	}
401}
402
403static void mcp4728_init_scale_avail(enum mcp4728_scale scale, int vref_mv,
404				     struct mcp4728_data *data)
405{
406	s64 tmp;
407	int value_micro;
408	int value_int;
409
410	tmp	  = (s64)vref_mv * 1000000LL >> MCP4728_RESOLUTION;
411	value_int = div_s64_rem(tmp, 1000000LL, &value_micro);
412
413	data->scales_avail[scale * 2]	  = value_int;
414	data->scales_avail[scale * 2 + 1] = value_micro;
415}
416
417static int mcp4728_init_scales_avail(struct mcp4728_data *data, int vdd_mv)
418{
419	mcp4728_init_scale_avail(MCP4728_SCALE_VDD, vdd_mv, data);
420	mcp4728_init_scale_avail(MCP4728_SCALE_VINT_NO_GAIN, 2048, data);
421	mcp4728_init_scale_avail(MCP4728_SCALE_VINT_GAIN_X2, 4096, data);
422
423	return 0;
424}
425
426static int mcp4728_read_avail(struct iio_dev *indio_dev,
427			      struct iio_chan_spec const *chan,
428			      const int **vals, int *type, int *length,
429			      long info)
430{
431	struct mcp4728_data *data = iio_priv(indio_dev);
432
433	switch (info) {
434	case IIO_CHAN_INFO_SCALE:
435		*type = IIO_VAL_INT_PLUS_MICRO;
436
437		switch (chan->type) {
438		case IIO_VOLTAGE:
439			*vals	= data->scales_avail;
440			*length = MCP4728_N_SCALES * 2;
441			return IIO_AVAIL_LIST;
442		default:
443			return -EINVAL;
444		}
445	default:
446		return -EINVAL;
447	}
448}
449
450static const struct iio_info mcp4728_info = {
451	.read_raw   = mcp4728_read_raw,
452	.write_raw  = mcp4728_write_raw,
453	.read_avail = &mcp4728_read_avail,
454	.attrs	    = &mcp4728_attribute_group,
455};
456
457static int mcp4728_suspend(struct device *dev)
458{
459	struct iio_dev *indio_dev = dev_get_drvdata(dev);
460	struct mcp4728_data *data = iio_priv(indio_dev);
461	unsigned int i;
462
463	data->powerdown = true;
464
465	for (i = 0; i < MCP4728_N_CHANNELS; i++) {
466		int err = mcp4728_program_channel_cfg(i, indio_dev);
467
468		if (err)
469			return err;
470	}
471	return 0;
472}
473
474static int mcp4728_resume(struct device *dev)
475{
476	struct iio_dev *indio_dev = dev_get_drvdata(dev);
477	struct mcp4728_data *data = iio_priv(indio_dev);
478	int err			  = 0;
479	unsigned int i;
480
481	data->powerdown = false;
482
483	for (i = 0; i < MCP4728_N_CHANNELS; i++) {
484		int ret = mcp4728_program_channel_cfg(i, indio_dev);
485
486		if (ret)
487			err = ret;
488	}
489	return err;
490}
491
492static DEFINE_SIMPLE_DEV_PM_OPS(mcp4728_pm_ops, mcp4728_suspend,
493				mcp4728_resume);
494
495static int mcp4728_init_channels_data(struct mcp4728_data *data)
496{
497	u8 inbuf[MCP4728_READ_RESPONSE_LEN];
498	int ret;
499	unsigned int i;
500
501	ret = i2c_master_recv(data->client, inbuf, MCP4728_READ_RESPONSE_LEN);
502	if (ret < 0) {
503		return dev_err_probe(&data->client->dev, ret,
504				     "failed to read mcp4728 conf.\n");
505	} else if (ret != MCP4728_READ_RESPONSE_LEN) {
506		return dev_err_probe(&data->client->dev, -EIO,
507			"failed to read mcp4728 conf. Wrong Response Len ret=%d\n",
508			ret);
509	}
510
511	for (i = 0; i < MCP4728_N_CHANNELS; i++) {
512		struct mcp4728_channel_data *ch = &data->chdata[i];
513		u8 r2				= inbuf[i * 6 + 1];
514		u8 r3				= inbuf[i * 6 + 2];
515
516		ch->dac_value = FIELD_GET(MCP4728_DAC_H_MASK, r2) << 8 |
517				FIELD_GET(MCP4728_DAC_L_MASK, r3);
518		ch->ref_mode = FIELD_GET(MCP4728_VREF_MASK, r2);
519		ch->pd_mode  = FIELD_GET(MCP4728_PDMODE_MASK, r2);
520		ch->g_mode   = FIELD_GET(MCP4728_GAIN_MASK, r2);
521	}
522
523	return 0;
524}
525
526static int mcp4728_probe(struct i2c_client *client)
527{
528	const struct i2c_device_id *id = i2c_client_get_device_id(client);
529	struct mcp4728_data *data;
530	struct iio_dev *indio_dev;
531	int ret, vdd_mv;
532
533	indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data));
534	if (!indio_dev)
535		return -ENOMEM;
536
537	data = iio_priv(indio_dev);
538	i2c_set_clientdata(client, indio_dev);
539	data->client = client;
540
541	ret = devm_regulator_get_enable_read_voltage(&client->dev, "vdd");
542	if (ret < 0)
543		return ret;
544
545	vdd_mv = ret / 1000;
546
547	/*
548	 * MCP4728 has internal EEPROM that save each channel boot
549	 * configuration. It means that device configuration is unknown to the
550	 * driver at kernel boot. mcp4728_init_channels_data() reads back DAC
551	 * settings and stores them in data structure.
552	 */
553	ret = mcp4728_init_channels_data(data);
554	if (ret) {
555		return dev_err_probe(&client->dev, ret,
556			"failed to read mcp4728 current configuration\n");
557	}
558
559	ret = mcp4728_init_scales_avail(data, vdd_mv);
560	if (ret) {
561		return dev_err_probe(&client->dev, ret,
562				     "failed to init scales\n");
563	}
564
565	indio_dev->name		= id->name;
566	indio_dev->info		= &mcp4728_info;
567	indio_dev->channels	= mcp4728_channels;
568	indio_dev->num_channels = MCP4728_N_CHANNELS;
569	indio_dev->modes	= INDIO_DIRECT_MODE;
570
571	return devm_iio_device_register(&client->dev, indio_dev);
572}
573
574static const struct i2c_device_id mcp4728_id[] = {
575	{ "mcp4728" },
576	{ }
577};
578MODULE_DEVICE_TABLE(i2c, mcp4728_id);
579
580static const struct of_device_id mcp4728_of_match[] = {
581	{ .compatible = "microchip,mcp4728" },
582	{ }
583};
584MODULE_DEVICE_TABLE(of, mcp4728_of_match);
585
586static struct i2c_driver mcp4728_driver = {
587	.driver = {
588		.name = "mcp4728",
589		.of_match_table = mcp4728_of_match,
590		.pm = pm_sleep_ptr(&mcp4728_pm_ops),
591	},
592	.probe = mcp4728_probe,
593	.id_table = mcp4728_id,
594};
595module_i2c_driver(mcp4728_driver);
596
597MODULE_AUTHOR("Andrea Collamati <andrea.collamati@gmail.com>");
598MODULE_DESCRIPTION("MCP4728 12-bit DAC");
599MODULE_LICENSE("GPL");