1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * BD79703 ROHM Digital to Analog converter
4 *
5 * Copyright (c) 2024, ROHM Semiconductor.
6 */
7
8 #include <linux/bits.h>
9 #include <linux/device.h>
10 #include <linux/module.h>
11 #include <linux/regmap.h>
12 #include <linux/regulator/consumer.h>
13 #include <linux/spi/spi.h>
14 #include <linux/iio/iio.h>
15
16 #define BD79703_MAX_REGISTER 0xf
17 #define BD79703_DAC_BITS 8
18 #define BD79703_REG_OUT_ALL GENMASK(2, 0)
19
20 /*
21 * The BD79703 uses 12-bit SPI commands. First four bits (high bits) define
22 * channel(s) which are operated on, and also the mode. The mode can be to set
23 * a DAC word only, or set DAC word and output. The data-sheet is not very
24 * specific on how a previously set DAC word can be 'taken in to use'. Thus
25 * this driver only uses the 'set DAC and output it' -mode.
26 *
27 * The BD79703 latches last 12-bits when the chip-select is toggled. Thus we
28 * can use 16-bit transfers which should be widely supported. To simplify this
29 * further, we treat the last 8 bits as a value, and first 8 bits as an
30 * address. This allows us to separate channels/mode by address and treat the
31 * 8-bit register value as DAC word. The highest 4 bits of address will be
32 * discarded when the transfer is latched.
33 */
34 static const struct regmap_config bd79703_regmap_config = {
35 .reg_bits = 8,
36 .val_bits = 8,
37 .max_register = BD79703_MAX_REGISTER,
38 .cache_type = REGCACHE_RBTREE,
39 };
40
41 struct bd79703_data {
42 struct regmap *regmap;
43 int vfs;
44 };
45
bd79703_read_raw(struct iio_dev * idev,struct iio_chan_spec const * chan,int * val,int * val2,long mask)46 static int bd79703_read_raw(struct iio_dev *idev,
47 struct iio_chan_spec const *chan, int *val,
48 int *val2, long mask)
49 {
50 struct bd79703_data *data = iio_priv(idev);
51
52 if (mask != IIO_CHAN_INFO_SCALE)
53 return -EINVAL;
54
55 *val = data->vfs / 1000;
56 *val2 = BD79703_DAC_BITS;
57
58 return IIO_VAL_FRACTIONAL_LOG2;
59 }
60
bd79703_write_raw(struct iio_dev * idev,struct iio_chan_spec const * chan,int val,int val2,long mask)61 static int bd79703_write_raw(struct iio_dev *idev,
62 struct iio_chan_spec const *chan, int val,
63 int val2, long mask)
64 {
65 struct bd79703_data *data = iio_priv(idev);
66
67 if (val < 0 || val >= 1 << BD79703_DAC_BITS)
68 return -EINVAL;
69
70 return regmap_write(data->regmap, chan->channel + 1, val);
71 };
72
73 static const struct iio_info bd79703_info = {
74 .read_raw = bd79703_read_raw,
75 .write_raw = bd79703_write_raw,
76 };
77
78 #define BD79703_CHAN(_chan) { \
79 .type = IIO_VOLTAGE, \
80 .indexed = 1, \
81 .output = 1, \
82 .channel = (_chan), \
83 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
84 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
85 .address = (_chan), \
86 }
87
88 static const struct iio_chan_spec bd79703_channels[] = {
89 BD79703_CHAN(0),
90 BD79703_CHAN(1),
91 BD79703_CHAN(2),
92 BD79703_CHAN(3),
93 BD79703_CHAN(4),
94 BD79703_CHAN(5),
95 };
96
bd79703_probe(struct spi_device * spi)97 static int bd79703_probe(struct spi_device *spi)
98 {
99 struct device *dev = &spi->dev;
100 struct bd79703_data *data;
101 struct iio_dev *idev;
102 int ret;
103
104 idev = devm_iio_device_alloc(dev, sizeof(*data));
105 if (!idev)
106 return -ENOMEM;
107
108 data = iio_priv(idev);
109
110 data->regmap = devm_regmap_init_spi(spi, &bd79703_regmap_config);
111 if (IS_ERR(data->regmap))
112 return dev_err_probe(dev, PTR_ERR(data->regmap),
113 "Failed to initialize Regmap\n");
114
115 ret = devm_regulator_get_enable(dev, "vcc");
116 if (ret)
117 return dev_err_probe(dev, ret, "Failed to enable VCC\n");
118
119 ret = devm_regulator_get_enable_read_voltage(dev, "vfs");
120 if (ret < 0)
121 return dev_err_probe(dev, ret, "Failed to get Vfs\n");
122
123 data->vfs = ret;
124 idev->channels = bd79703_channels;
125 idev->num_channels = ARRAY_SIZE(bd79703_channels);
126 idev->modes = INDIO_DIRECT_MODE;
127 idev->info = &bd79703_info;
128 idev->name = "bd79703";
129
130 /* Initialize all to output zero */
131 ret = regmap_write(data->regmap, BD79703_REG_OUT_ALL, 0);
132 if (ret)
133 return ret;
134
135 return devm_iio_device_register(dev, idev);
136 }
137
138 static const struct spi_device_id bd79703_id[] = {
139 { "bd79703", },
140 { }
141 };
142 MODULE_DEVICE_TABLE(spi, bd79703_id);
143
144 static const struct of_device_id bd79703_of_match[] = {
145 { .compatible = "rohm,bd79703", },
146 { }
147 };
148 MODULE_DEVICE_TABLE(of, bd79703_of_match);
149
150 static struct spi_driver bd79703_driver = {
151 .driver = {
152 .name = "bd79703",
153 .of_match_table = bd79703_of_match,
154 },
155 .probe = bd79703_probe,
156 .id_table = bd79703_id,
157 };
158 module_spi_driver(bd79703_driver);
159
160 MODULE_AUTHOR("Matti Vaittinen <[email protected]>");
161 MODULE_DESCRIPTION("ROHM BD79703 DAC driver");
162 MODULE_LICENSE("GPL");
163