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 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 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 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 <mazziesaccount@gmail.com>"); 161 MODULE_DESCRIPTION("ROHM BD79703 DAC driver"); 162 MODULE_LICENSE("GPL"); 163