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- // SPDX-License-Identifier: GPL-2.0
- /*
- * DAC7612 Dual, 12-Bit Serial input Digital-to-Analog Converter
- *
- * Copyright 2019 Qtechnology A/S
- * 2019 Ricardo Ribalda <[email protected]>
- *
- * Licensed under the GPL-2.
- */
- #include <linux/kernel.h>
- #include <linux/module.h>
- #include <linux/spi/spi.h>
- #include <linux/gpio/consumer.h>
- #include <linux/iio/iio.h>
- #define DAC7612_RESOLUTION 12
- #define DAC7612_ADDRESS 4
- #define DAC7612_START 5
- struct dac7612 {
- struct spi_device *spi;
- struct gpio_desc *loaddacs;
- uint16_t cache[2];
- /*
- * Lock to protect the state of the device from potential concurrent
- * write accesses from userspace. The write operation requires an
- * SPI write, then toggling of a GPIO, so the lock aims to protect
- * the sanity of the entire sequence of operation.
- */
- struct mutex lock;
- /*
- * DMA (thus cache coherency maintenance) may require the
- * transfer buffers to live in their own cache lines.
- */
- uint8_t data[2] __aligned(IIO_DMA_MINALIGN);
- };
- static int dac7612_cmd_single(struct dac7612 *priv, int channel, u16 val)
- {
- int ret;
- priv->data[0] = BIT(DAC7612_START) | (channel << DAC7612_ADDRESS);
- priv->data[0] |= val >> 8;
- priv->data[1] = val & 0xff;
- priv->cache[channel] = val;
- ret = spi_write(priv->spi, priv->data, sizeof(priv->data));
- if (ret)
- return ret;
- gpiod_set_value(priv->loaddacs, 1);
- gpiod_set_value(priv->loaddacs, 0);
- return 0;
- }
- #define dac7612_CHANNEL(chan, name) { \
- .type = IIO_VOLTAGE, \
- .channel = (chan), \
- .indexed = 1, \
- .output = 1, \
- .datasheet_name = name, \
- .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
- .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
- }
- static const struct iio_chan_spec dac7612_channels[] = {
- dac7612_CHANNEL(0, "OUTA"),
- dac7612_CHANNEL(1, "OUTB"),
- };
- static int dac7612_read_raw(struct iio_dev *iio_dev,
- const struct iio_chan_spec *chan,
- int *val, int *val2, long mask)
- {
- struct dac7612 *priv;
- switch (mask) {
- case IIO_CHAN_INFO_RAW:
- priv = iio_priv(iio_dev);
- *val = priv->cache[chan->channel];
- return IIO_VAL_INT;
- case IIO_CHAN_INFO_SCALE:
- *val = 1;
- return IIO_VAL_INT;
- default:
- return -EINVAL;
- }
- }
- static int dac7612_write_raw(struct iio_dev *iio_dev,
- const struct iio_chan_spec *chan,
- int val, int val2, long mask)
- {
- struct dac7612 *priv = iio_priv(iio_dev);
- int ret;
- if (mask != IIO_CHAN_INFO_RAW)
- return -EINVAL;
- if ((val >= BIT(DAC7612_RESOLUTION)) || val < 0 || val2)
- return -EINVAL;
- if (val == priv->cache[chan->channel])
- return 0;
- mutex_lock(&priv->lock);
- ret = dac7612_cmd_single(priv, chan->channel, val);
- mutex_unlock(&priv->lock);
- return ret;
- }
- static const struct iio_info dac7612_info = {
- .read_raw = dac7612_read_raw,
- .write_raw = dac7612_write_raw,
- };
- static int dac7612_probe(struct spi_device *spi)
- {
- struct iio_dev *iio_dev;
- struct dac7612 *priv;
- int i;
- int ret;
- iio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*priv));
- if (!iio_dev)
- return -ENOMEM;
- priv = iio_priv(iio_dev);
- /*
- * LOADDACS pin can be controlled by the driver or externally.
- * When controlled by the driver, the DAC value is updated after
- * every write.
- * When the driver does not control the PIN, the user or an external
- * event can change the value of all DACs by pulsing down the LOADDACs
- * pin.
- */
- priv->loaddacs = devm_gpiod_get_optional(&spi->dev, "ti,loaddacs",
- GPIOD_OUT_LOW);
- if (IS_ERR(priv->loaddacs))
- return PTR_ERR(priv->loaddacs);
- priv->spi = spi;
- spi_set_drvdata(spi, iio_dev);
- iio_dev->info = &dac7612_info;
- iio_dev->modes = INDIO_DIRECT_MODE;
- iio_dev->channels = dac7612_channels;
- iio_dev->num_channels = ARRAY_SIZE(priv->cache);
- iio_dev->name = spi_get_device_id(spi)->name;
- mutex_init(&priv->lock);
- for (i = 0; i < ARRAY_SIZE(priv->cache); i++) {
- ret = dac7612_cmd_single(priv, i, 0);
- if (ret)
- return ret;
- }
- return devm_iio_device_register(&spi->dev, iio_dev);
- }
- static const struct spi_device_id dac7612_id[] = {
- {"ti-dac7612"},
- {}
- };
- MODULE_DEVICE_TABLE(spi, dac7612_id);
- static const struct of_device_id dac7612_of_match[] = {
- { .compatible = "ti,dac7612" },
- { .compatible = "ti,dac7612u" },
- { .compatible = "ti,dac7612ub" },
- { },
- };
- MODULE_DEVICE_TABLE(of, dac7612_of_match);
- static struct spi_driver dac7612_driver = {
- .driver = {
- .name = "ti-dac7612",
- .of_match_table = dac7612_of_match,
- },
- .probe = dac7612_probe,
- .id_table = dac7612_id,
- };
- module_spi_driver(dac7612_driver);
- MODULE_AUTHOR("Ricardo Ribalda <[email protected]>");
- MODULE_DESCRIPTION("Texas Instruments DAC7612 DAC driver");
- MODULE_LICENSE("GPL v2");
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