1 /* 2 * mcp4922.c 3 * 4 * Driver for Microchip Digital to Analog Converters. 5 * Supports MCP4902, MCP4912, and MCP4922. 6 * 7 * Copyright (c) 2014 EMAC Inc. 8 * 9 * This program is free software; you can redistribute it and/or modify 10 * it under the terms of the GNU General Public License as published by 11 * the Free Software Foundation; either version 2 of the License, or 12 * (at your option) any later version. 13 * 14 * This program is distributed in the hope that it will be useful, 15 * but WITHOUT ANY WARRANTY; without even the implied warranty of 16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 17 * GNU General Public License for more details. 18 * 19 */ 20 21 #include <linux/module.h> 22 #include <linux/init.h> 23 #include <linux/spi/spi.h> 24 #include <linux/iio/iio.h> 25 #include <linux/iio/sysfs.h> 26 #include <linux/regulator/consumer.h> 27 #include <linux/bitops.h> 28 29 #define MCP4922_NUM_CHANNELS 2 30 31 enum mcp4922_supported_device_ids { 32 ID_MCP4902, 33 ID_MCP4912, 34 ID_MCP4922, 35 }; 36 37 struct mcp4922_state { 38 struct spi_device *spi; 39 unsigned int value[MCP4922_NUM_CHANNELS]; 40 unsigned int vref_mv; 41 struct regulator *vref_reg; 42 u8 mosi[2] ____cacheline_aligned; 43 }; 44 45 #define MCP4922_CHAN(chan, bits) { \ 46 .type = IIO_VOLTAGE, \ 47 .output = 1, \ 48 .indexed = 1, \ 49 .channel = chan, \ 50 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 51 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 52 .scan_type = { \ 53 .sign = 'u', \ 54 .realbits = (bits), \ 55 .storagebits = 16, \ 56 .shift = 12 - (bits), \ 57 }, \ 58 } 59 60 static int mcp4922_spi_write(struct mcp4922_state *state, u8 addr, u32 val) 61 { 62 state->mosi[1] = val & 0xff; 63 state->mosi[0] = (addr == 0) ? 0x00 : 0x80; 64 state->mosi[0] |= 0x30 | ((val >> 8) & 0x0f); 65 66 return spi_write(state->spi, state->mosi, 2); 67 } 68 69 static int mcp4922_read_raw(struct iio_dev *indio_dev, 70 struct iio_chan_spec const *chan, 71 int *val, 72 int *val2, 73 long mask) 74 { 75 struct mcp4922_state *state = iio_priv(indio_dev); 76 77 switch (mask) { 78 case IIO_CHAN_INFO_RAW: 79 *val = state->value[chan->channel]; 80 return IIO_VAL_INT; 81 case IIO_CHAN_INFO_SCALE: 82 *val = state->vref_mv; 83 *val2 = chan->scan_type.realbits; 84 return IIO_VAL_FRACTIONAL_LOG2; 85 default: 86 return -EINVAL; 87 } 88 } 89 90 static int mcp4922_write_raw(struct iio_dev *indio_dev, 91 struct iio_chan_spec const *chan, 92 int val, 93 int val2, 94 long mask) 95 { 96 struct mcp4922_state *state = iio_priv(indio_dev); 97 98 if (val2 != 0) 99 return -EINVAL; 100 101 switch (mask) { 102 case IIO_CHAN_INFO_RAW: 103 if (val > GENMASK(chan->scan_type.realbits-1, 0)) 104 return -EINVAL; 105 val <<= chan->scan_type.shift; 106 state->value[chan->channel] = val; 107 return mcp4922_spi_write(state, chan->channel, val); 108 default: 109 return -EINVAL; 110 } 111 } 112 113 static const struct iio_chan_spec mcp4922_channels[3][MCP4922_NUM_CHANNELS] = { 114 [ID_MCP4902] = { MCP4922_CHAN(0, 8), MCP4922_CHAN(1, 8) }, 115 [ID_MCP4912] = { MCP4922_CHAN(0, 10), MCP4922_CHAN(1, 10) }, 116 [ID_MCP4922] = { MCP4922_CHAN(0, 12), MCP4922_CHAN(1, 12) }, 117 }; 118 119 static const struct iio_info mcp4922_info = { 120 .read_raw = &mcp4922_read_raw, 121 .write_raw = &mcp4922_write_raw, 122 .driver_module = THIS_MODULE, 123 }; 124 125 static int mcp4922_probe(struct spi_device *spi) 126 { 127 struct iio_dev *indio_dev; 128 struct mcp4922_state *state; 129 const struct spi_device_id *id; 130 int ret; 131 132 indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*state)); 133 if (indio_dev == NULL) 134 return -ENOMEM; 135 136 state = iio_priv(indio_dev); 137 state->spi = spi; 138 state->vref_reg = devm_regulator_get(&spi->dev, "vref"); 139 if (IS_ERR(state->vref_reg)) { 140 dev_err(&spi->dev, "Vref regulator not specified\n"); 141 return PTR_ERR(state->vref_reg); 142 } 143 144 ret = regulator_enable(state->vref_reg); 145 if (ret) { 146 dev_err(&spi->dev, "Failed to enable vref regulator: %d\n", 147 ret); 148 return ret; 149 } 150 151 ret = regulator_get_voltage(state->vref_reg); 152 if (ret < 0) { 153 dev_err(&spi->dev, "Failed to read vref regulator: %d\n", 154 ret); 155 goto error_disable_reg; 156 } 157 state->vref_mv = ret / 1000; 158 159 spi_set_drvdata(spi, indio_dev); 160 id = spi_get_device_id(spi); 161 indio_dev->dev.parent = &spi->dev; 162 indio_dev->info = &mcp4922_info; 163 indio_dev->modes = INDIO_DIRECT_MODE; 164 indio_dev->channels = mcp4922_channels[id->driver_data]; 165 indio_dev->num_channels = MCP4922_NUM_CHANNELS; 166 indio_dev->name = id->name; 167 168 ret = iio_device_register(indio_dev); 169 if (ret) { 170 dev_err(&spi->dev, "Failed to register iio device: %d\n", 171 ret); 172 goto error_disable_reg; 173 } 174 175 return 0; 176 177 error_disable_reg: 178 regulator_disable(state->vref_reg); 179 180 return ret; 181 } 182 183 static int mcp4922_remove(struct spi_device *spi) 184 { 185 struct iio_dev *indio_dev = spi_get_drvdata(spi); 186 struct mcp4922_state *state; 187 188 iio_device_unregister(indio_dev); 189 state = iio_priv(indio_dev); 190 regulator_disable(state->vref_reg); 191 192 return 0; 193 } 194 195 static const struct spi_device_id mcp4922_id[] = { 196 {"mcp4902", ID_MCP4902}, 197 {"mcp4912", ID_MCP4912}, 198 {"mcp4922", ID_MCP4922}, 199 {} 200 }; 201 MODULE_DEVICE_TABLE(spi, mcp4922_id); 202 203 static struct spi_driver mcp4922_driver = { 204 .driver = { 205 .name = "mcp4922", 206 }, 207 .probe = mcp4922_probe, 208 .remove = mcp4922_remove, 209 .id_table = mcp4922_id, 210 }; 211 module_spi_driver(mcp4922_driver); 212 213 MODULE_AUTHOR("Michael Welling <mwelling@ieee.org>"); 214 MODULE_DESCRIPTION("Microchip MCP4902, MCP4912, MCP4922 DAC"); 215 MODULE_LICENSE("GPL v2"); 216