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1// SPDX-License-Identifier: GPL-2.02/*3 * DAC7612 Dual, 12-Bit Serial input Digital-to-Analog Converter4 *5 * Copyright 2019 Qtechnology A/S6 * 2019 Ricardo Ribalda <ribalda@kernel.org>7 *8 * Licensed under the GPL-2.9 */10#include <linux/kernel.h>11#include <linux/module.h>12#include <linux/spi/spi.h>13#include <linux/gpio/consumer.h>14#include <linux/iio/iio.h>15 16#define DAC7612_RESOLUTION 1217#define DAC7612_ADDRESS 418#define DAC7612_START 519 20struct dac7612 {21 struct spi_device *spi;22 struct gpio_desc *loaddacs;23 uint16_t cache[2];24 25 /*26 * Lock to protect the state of the device from potential concurrent27 * write accesses from userspace. The write operation requires an28 * SPI write, then toggling of a GPIO, so the lock aims to protect29 * the sanity of the entire sequence of operation.30 */31 struct mutex lock;32 33 /*34 * DMA (thus cache coherency maintenance) may require the35 * transfer buffers to live in their own cache lines.36 */37 uint8_t data[2] __aligned(IIO_DMA_MINALIGN);38};39 40static int dac7612_cmd_single(struct dac7612 *priv, int channel, u16 val)41{42 int ret;43 44 priv->data[0] = BIT(DAC7612_START) | (channel << DAC7612_ADDRESS);45 priv->data[0] |= val >> 8;46 priv->data[1] = val & 0xff;47 48 priv->cache[channel] = val;49 50 ret = spi_write(priv->spi, priv->data, sizeof(priv->data));51 if (ret)52 return ret;53 54 gpiod_set_value(priv->loaddacs, 1);55 gpiod_set_value(priv->loaddacs, 0);56 57 return 0;58}59 60#define dac7612_CHANNEL(chan, name) { \61 .type = IIO_VOLTAGE, \62 .channel = (chan), \63 .indexed = 1, \64 .output = 1, \65 .datasheet_name = name, \66 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \67 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \68}69 70static const struct iio_chan_spec dac7612_channels[] = {71 dac7612_CHANNEL(0, "OUTA"),72 dac7612_CHANNEL(1, "OUTB"),73};74 75static int dac7612_read_raw(struct iio_dev *iio_dev,76 const struct iio_chan_spec *chan,77 int *val, int *val2, long mask)78{79 struct dac7612 *priv;80 81 switch (mask) {82 case IIO_CHAN_INFO_RAW:83 priv = iio_priv(iio_dev);84 *val = priv->cache[chan->channel];85 return IIO_VAL_INT;86 87 case IIO_CHAN_INFO_SCALE:88 *val = 1;89 return IIO_VAL_INT;90 91 default:92 return -EINVAL;93 }94}95 96static int dac7612_write_raw(struct iio_dev *iio_dev,97 const struct iio_chan_spec *chan,98 int val, int val2, long mask)99{100 struct dac7612 *priv = iio_priv(iio_dev);101 int ret;102 103 if (mask != IIO_CHAN_INFO_RAW)104 return -EINVAL;105 106 if ((val >= BIT(DAC7612_RESOLUTION)) || val < 0 || val2)107 return -EINVAL;108 109 if (val == priv->cache[chan->channel])110 return 0;111 112 mutex_lock(&priv->lock);113 ret = dac7612_cmd_single(priv, chan->channel, val);114 mutex_unlock(&priv->lock);115 116 return ret;117}118 119static const struct iio_info dac7612_info = {120 .read_raw = dac7612_read_raw,121 .write_raw = dac7612_write_raw,122};123 124static int dac7612_probe(struct spi_device *spi)125{126 struct iio_dev *iio_dev;127 struct dac7612 *priv;128 int i;129 int ret;130 131 iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));132 if (!iio_dev)133 return -ENOMEM;134 135 priv = iio_priv(iio_dev);136 /*137 * LOADDACS pin can be controlled by the driver or externally.138 * When controlled by the driver, the DAC value is updated after139 * every write.140 * When the driver does not control the PIN, the user or an external141 * event can change the value of all DACs by pulsing down the LOADDACs142 * pin.143 */144 priv->loaddacs = devm_gpiod_get_optional(&spi->dev, "ti,loaddacs",145 GPIOD_OUT_LOW);146 if (IS_ERR(priv->loaddacs))147 return PTR_ERR(priv->loaddacs);148 priv->spi = spi;149 spi_set_drvdata(spi, iio_dev);150 iio_dev->info = &dac7612_info;151 iio_dev->modes = INDIO_DIRECT_MODE;152 iio_dev->channels = dac7612_channels;153 iio_dev->num_channels = ARRAY_SIZE(priv->cache);154 iio_dev->name = spi_get_device_id(spi)->name;155 156 mutex_init(&priv->lock);157 158 for (i = 0; i < ARRAY_SIZE(priv->cache); i++) {159 ret = dac7612_cmd_single(priv, i, 0);160 if (ret)161 return ret;162 }163 164 return devm_iio_device_register(&spi->dev, iio_dev);165}166 167static const struct spi_device_id dac7612_id[] = {168 {"ti-dac7612"},169 {}170};171MODULE_DEVICE_TABLE(spi, dac7612_id);172 173static const struct of_device_id dac7612_of_match[] = {174 { .compatible = "ti,dac7612" },175 { .compatible = "ti,dac7612u" },176 { .compatible = "ti,dac7612ub" },177 { },178};179MODULE_DEVICE_TABLE(of, dac7612_of_match);180 181static struct spi_driver dac7612_driver = {182 .driver = {183 .name = "ti-dac7612",184 .of_match_table = dac7612_of_match,185 },186 .probe = dac7612_probe,187 .id_table = dac7612_id,188};189module_spi_driver(dac7612_driver);190 191MODULE_AUTHOR("Ricardo Ribalda <ribalda@kernel.org>");192MODULE_DESCRIPTION("Texas Instruments DAC7612 DAC driver");193MODULE_LICENSE("GPL v2");194