1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * mcp4922.c 4 * 5 * Driver for Microchip Digital to Analog Converters. 6 * Supports MCP4902, MCP4912, and MCP4922. 7 * 8 * Copyright (c) 2014 EMAC Inc. 9 */ 10 11 #include <linux/module.h> 12 #include <linux/init.h> 13 #include <linux/spi/spi.h> 14 #include <linux/iio/iio.h> 15 #include <linux/iio/sysfs.h> 16 #include <linux/regulator/consumer.h> 17 #include <linux/bitops.h> 18 19 #define MCP4922_NUM_CHANNELS 2 20 #define MCP4921_NUM_CHANNELS 1 21 22 enum mcp4922_supported_device_ids { 23 ID_MCP4902, 24 ID_MCP4912, 25 ID_MCP4921, 26 ID_MCP4922, 27 }; 28 29 struct mcp4922_state { 30 struct spi_device *spi; 31 unsigned int value[MCP4922_NUM_CHANNELS]; 32 unsigned int vref_mv; 33 u8 mosi[2] __aligned(IIO_DMA_MINALIGN); 34 }; 35 36 #define MCP4922_CHAN(chan, bits) { \ 37 .type = IIO_VOLTAGE, \ 38 .output = 1, \ 39 .indexed = 1, \ 40 .channel = chan, \ 41 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 42 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 43 .scan_type = { \ 44 .sign = 'u', \ 45 .realbits = (bits), \ 46 .storagebits = 16, \ 47 .shift = 12 - (bits), \ 48 }, \ 49 } 50 51 static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val) 52 { 53 state->mosi[1] = val & 0xff; 54 state->mosi[0] = (addr == 0) ? 0x00 : 0x80; 55 state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f); 56 57 return spi_write(state->spi, state->mosi, 2); 58 } 59 60 static int mcp4922_read_raw(struct iio_dev *indio_dev, 61 struct iio_chan_spec const *chan, 62 int *val, 63 int *val2, 64 long mask) 65 { 66 struct mcp4922_state *state = iio_priv(indio_dev); 67 68 switch (mask) { 69 case IIO_CHAN_INFO_RAW: 70 *val = state->value[chan->channel]; 71 return IIO_VAL_INT; 72 case IIO_CHAN_INFO_SCALE: 73 *val = state->vref_mv; 74 *val2 = chan->scan_type.realbits; 75 return IIO_VAL_FRACTIONAL_LOG2; 76 default: 77 return -EINVAL; 78 } 79 } 80 81 static int mcp4922_write_raw(struct iio_dev *indio_dev, 82 struct iio_chan_spec const *chan, 83 int val, 84 int val2, 85 long mask) 86 { 87 struct mcp4922_state *state = iio_priv(indio_dev); 88 int ret; 89 90 if (val2 != 0) 91 return -EINVAL; 92 93 switch (mask) { 94 case IIO_CHAN_INFO_RAW: 95 if (val < 0 || val > GENMASK(chan->scan_type.realbits - 1, 0)) 96 return -EINVAL; 97 val <<= chan->scan_type.shift; 98 99 ret = mcp4922_spi_write(state, chan->channel, val); 100 if (!ret) 101 state->value[chan->channel] = val; 102 return ret; 103 104 default: 105 return -EINVAL; 106 } 107 } 108 109 static const struct iio_chan_spec mcp4922_channels[4][MCP4922_NUM_CHANNELS] = { 110 [ID_MCP4902] = { MCP4922_CHAN(0, 8), MCP4922_CHAN(1, 8) }, 111 [ID_MCP4912] = { MCP4922_CHAN(0, 10), MCP4922_CHAN(1, 10) }, 112 [ID_MCP4921] = { MCP4922_CHAN(0, 12), {} }, 113 [ID_MCP4922] = { MCP4922_CHAN(0, 12), MCP4922_CHAN(1, 12) }, 114 }; 115 116 static const struct iio_info mcp4922_info = { 117 .read_raw = &mcp4922_read_raw, 118 .write_raw = &mcp4922_write_raw, 119 }; 120 121 static int mcp4922_probe(struct spi_device *spi) 122 { 123 struct iio_dev *indio_dev; 124 struct mcp4922_state *state; 125 const struct spi_device_id *id; 126 int ret; 127 128 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state)); 129 if (indio_dev == NULL) 130 return -ENOMEM; 131 132 state = iio_priv(indio_dev); 133 state->spi = spi; 134 135 ret = devm_regulator_get_enable_read_voltage(&spi->dev, "vref"); 136 if (ret < 0) 137 return dev_err_probe(&spi->dev, ret, "Failed to get vref voltage\n"); 138 139 state->vref_mv = ret / 1000; 140 141 id = spi_get_device_id(spi); 142 indio_dev->info = &mcp4922_info; 143 indio_dev->modes = INDIO_DIRECT_MODE; 144 indio_dev->channels = mcp4922_channels[id->driver_data]; 145 if (id->driver_data == ID_MCP4921) 146 indio_dev->num_channels = MCP4921_NUM_CHANNELS; 147 else 148 indio_dev->num_channels = MCP4922_NUM_CHANNELS; 149 indio_dev->name = id->name; 150 151 ret = devm_iio_device_register(&spi->dev, indio_dev); 152 if (ret) 153 return dev_err_probe(&spi->dev, ret, "Failed to register iio device\n"); 154 155 return 0; 156 } 157 158 159 static const struct spi_device_id mcp4922_id[] = { 160 {"mcp4902", ID_MCP4902}, 161 {"mcp4912", ID_MCP4912}, 162 {"mcp4921", ID_MCP4921}, 163 {"mcp4922", ID_MCP4922}, 164 {} 165 }; 166 MODULE_DEVICE_TABLE(spi, mcp4922_id); 167 168 static struct spi_driver mcp4922_driver = { 169 .driver = { 170 .name = "mcp4922", 171 }, 172 .probe = mcp4922_probe, 173 .id_table = mcp4922_id, 174 }; 175 module_spi_driver(mcp4922_driver); 176 177 MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>"); 178 MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC"); 179 MODULE_LICENSE("GPL v2"); 180