1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Driver for Linear Technology LTC1665/LTC1660, 8 channels DAC
4  *
5  * Copyright (C) 2018 Marcus Folkesson <marcus.folkesson@gmail.com>
6  */
7 #include <linux/bitops.h>
8 #include <linux/iio/iio.h>
9 #include <linux/iio/sysfs.h>
10 #include <linux/init.h>
11 #include <linux/module.h>
12 #include <linux/regulator/consumer.h>
13 #include <linux/regmap.h>
14 #include <linux/spi/spi.h>
15 
16 #define LTC1660_REG_WAKE	0x0
17 #define LTC1660_REG_DAC_A	0x1
18 #define LTC1660_REG_DAC_B	0x2
19 #define LTC1660_REG_DAC_C	0x3
20 #define LTC1660_REG_DAC_D	0x4
21 #define LTC1660_REG_DAC_E	0x5
22 #define LTC1660_REG_DAC_F	0x6
23 #define LTC1660_REG_DAC_G	0x7
24 #define LTC1660_REG_DAC_H	0x8
25 #define LTC1660_REG_SLEEP	0xe
26 
27 #define LTC1660_NUM_CHANNELS	8
28 
29 static const struct regmap_config ltc1660_regmap_config = {
30 	.reg_bits = 4,
31 	.val_bits = 12,
32 };
33 
34 enum ltc1660_supported_device_ids {
35 	ID_LTC1660,
36 	ID_LTC1665,
37 };
38 
39 struct ltc1660_priv {
40 	struct spi_device *spi;
41 	struct regmap *regmap;
42 	struct regulator *vref_reg;
43 	unsigned int value[LTC1660_NUM_CHANNELS];
44 	unsigned int vref_mv;
45 };
46 
ltc1660_read_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)47 static int ltc1660_read_raw(struct iio_dev *indio_dev,
48 		struct iio_chan_spec const *chan,
49 		int *val,
50 		int *val2,
51 		long mask)
52 {
53 	struct ltc1660_priv *priv = iio_priv(indio_dev);
54 
55 	switch (mask) {
56 	case IIO_CHAN_INFO_RAW:
57 		*val = priv->value[chan->channel];
58 		return IIO_VAL_INT;
59 	case IIO_CHAN_INFO_SCALE:
60 		*val = regulator_get_voltage(priv->vref_reg);
61 		if (*val < 0) {
62 			dev_err(&priv->spi->dev, "failed to read vref regulator: %d\n",
63 					*val);
64 			return *val;
65 		}
66 
67 		/* Convert to mV */
68 		*val /= 1000;
69 		*val2 = chan->scan_type.realbits;
70 		return IIO_VAL_FRACTIONAL_LOG2;
71 	default:
72 		return -EINVAL;
73 	}
74 }
75 
ltc1660_write_raw(struct iio_dev * indio_dev,struct iio_chan_spec const * chan,int val,int val2,long mask)76 static int ltc1660_write_raw(struct iio_dev *indio_dev,
77 		struct iio_chan_spec const *chan,
78 		int val,
79 		int val2,
80 		long mask)
81 {
82 	struct ltc1660_priv *priv = iio_priv(indio_dev);
83 	int ret;
84 
85 	switch (mask) {
86 	case IIO_CHAN_INFO_RAW:
87 		if (val2 != 0)
88 			return -EINVAL;
89 
90 		if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0))
91 			return -EINVAL;
92 
93 		ret = regmap_write(priv->regmap, chan->channel,
94 					(val << chan->scan_type.shift));
95 		if (!ret)
96 			priv->value[chan->channel] = val;
97 
98 		return ret;
99 	default:
100 		return -EINVAL;
101 	}
102 }
103 
104 #define LTC1660_CHAN(chan, bits) {			\
105 	.type = IIO_VOLTAGE,				\
106 	.indexed = 1,					\
107 	.output = 1,					\
108 	.channel = chan,				\
109 	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),	\
110 	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
111 	.scan_type = {					\
112 		.sign = 'u',				\
113 		.realbits = (bits),			\
114 		.storagebits = 16,			\
115 		.shift = 12 - (bits),			\
116 	},						\
117 }
118 
119 #define  LTC1660_OCTAL_CHANNELS(bits) {			\
120 		LTC1660_CHAN(LTC1660_REG_DAC_A, bits),	\
121 		LTC1660_CHAN(LTC1660_REG_DAC_B, bits),	\
122 		LTC1660_CHAN(LTC1660_REG_DAC_C, bits),	\
123 		LTC1660_CHAN(LTC1660_REG_DAC_D, bits),	\
124 		LTC1660_CHAN(LTC1660_REG_DAC_E, bits),	\
125 		LTC1660_CHAN(LTC1660_REG_DAC_F, bits),	\
126 		LTC1660_CHAN(LTC1660_REG_DAC_G, bits),	\
127 		LTC1660_CHAN(LTC1660_REG_DAC_H, bits),	\
128 }
129 
130 static const struct iio_chan_spec ltc1660_channels[][LTC1660_NUM_CHANNELS] = {
131 	[ID_LTC1660] = LTC1660_OCTAL_CHANNELS(10),
132 	[ID_LTC1665] = LTC1660_OCTAL_CHANNELS(8),
133 };
134 
135 static const struct iio_info ltc1660_info = {
136 	.read_raw = &ltc1660_read_raw,
137 	.write_raw = &ltc1660_write_raw,
138 };
139 
ltc1660_suspend(struct device * dev)140 static int __maybe_unused ltc1660_suspend(struct device *dev)
141 {
142 	struct ltc1660_priv *priv = iio_priv(spi_get_drvdata(
143 						to_spi_device(dev)));
144 	return regmap_write(priv->regmap, LTC1660_REG_SLEEP, 0x00);
145 }
146 
ltc1660_resume(struct device * dev)147 static int __maybe_unused ltc1660_resume(struct device *dev)
148 {
149 	struct ltc1660_priv *priv = iio_priv(spi_get_drvdata(
150 						to_spi_device(dev)));
151 	return regmap_write(priv->regmap, LTC1660_REG_WAKE, 0x00);
152 }
153 static SIMPLE_DEV_PM_OPS(ltc1660_pm_ops, ltc1660_suspend, ltc1660_resume);
154 
ltc1660_probe(struct spi_device * spi)155 static int ltc1660_probe(struct spi_device *spi)
156 {
157 	struct iio_dev *indio_dev;
158 	struct ltc1660_priv *priv;
159 	const struct spi_device_id *id = spi_get_device_id(spi);
160 	int ret;
161 
162 	indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));
163 	if (indio_dev == NULL)
164 		return -ENOMEM;
165 
166 	priv = iio_priv(indio_dev);
167 	priv->regmap = devm_regmap_init_spi(spi, &ltc1660_regmap_config);
168 	if (IS_ERR(priv->regmap)) {
169 		dev_err(&spi->dev, "failed to register spi regmap %ld\n",
170 			PTR_ERR(priv->regmap));
171 		return PTR_ERR(priv->regmap);
172 	}
173 
174 	priv->vref_reg = devm_regulator_get(&spi->dev, "vref");
175 	if (IS_ERR(priv->vref_reg))
176 		return dev_err_probe(&spi->dev, PTR_ERR(priv->vref_reg),
177 				     "vref regulator not specified\n");
178 
179 	ret = regulator_enable(priv->vref_reg);
180 	if (ret) {
181 		dev_err(&spi->dev, "failed to enable vref regulator: %d\n",
182 				ret);
183 		return ret;
184 	}
185 
186 	priv->spi = spi;
187 	spi_set_drvdata(spi, indio_dev);
188 	indio_dev->info = &ltc1660_info;
189 	indio_dev->modes = INDIO_DIRECT_MODE;
190 	indio_dev->channels = ltc1660_channels[id->driver_data];
191 	indio_dev->num_channels = LTC1660_NUM_CHANNELS;
192 	indio_dev->name = id->name;
193 
194 	ret = iio_device_register(indio_dev);
195 	if (ret) {
196 		dev_err(&spi->dev, "failed to register iio device: %d\n",
197 				ret);
198 		goto error_disable_reg;
199 	}
200 
201 	return 0;
202 
203 error_disable_reg:
204 	regulator_disable(priv->vref_reg);
205 
206 	return ret;
207 }
208 
ltc1660_remove(struct spi_device * spi)209 static int ltc1660_remove(struct spi_device *spi)
210 {
211 	struct iio_dev *indio_dev = spi_get_drvdata(spi);
212 	struct ltc1660_priv *priv = iio_priv(indio_dev);
213 
214 	iio_device_unregister(indio_dev);
215 	regulator_disable(priv->vref_reg);
216 
217 	return 0;
218 }
219 
220 static const struct of_device_id ltc1660_dt_ids[] = {
221 	{ .compatible = "lltc,ltc1660", .data = (void *)ID_LTC1660 },
222 	{ .compatible = "lltc,ltc1665", .data = (void *)ID_LTC1665 },
223 	{ /* sentinel */ }
224 };
225 MODULE_DEVICE_TABLE(of, ltc1660_dt_ids);
226 
227 static const struct spi_device_id ltc1660_id[] = {
228 	{"ltc1660", ID_LTC1660},
229 	{"ltc1665", ID_LTC1665},
230 	{ /* sentinel */ }
231 };
232 MODULE_DEVICE_TABLE(spi, ltc1660_id);
233 
234 static struct spi_driver ltc1660_driver = {
235 	.driver = {
236 		.name = "ltc1660",
237 		.of_match_table = ltc1660_dt_ids,
238 		.pm = &ltc1660_pm_ops,
239 	},
240 	.probe	= ltc1660_probe,
241 	.remove = ltc1660_remove,
242 	.id_table = ltc1660_id,
243 };
244 module_spi_driver(ltc1660_driver);
245 
246 MODULE_AUTHOR("Marcus Folkesson <marcus.folkesson@gmail.com>");
247 MODULE_DESCRIPTION("Linear Technology LTC1660/LTC1665 DAC");
248 MODULE_LICENSE("GPL v2");
249