diff options
Diffstat (limited to 'drivers/iio/dac/ti-dac7612.c')
| -rw-r--r-- | drivers/iio/dac/ti-dac7612.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/drivers/iio/dac/ti-dac7612.c b/drivers/iio/dac/ti-dac7612.c new file mode 100644 index 000000000..4c0f4b5e9 --- /dev/null +++ b/drivers/iio/dac/ti-dac7612.c @@ -0,0 +1,193 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * DAC7612 Dual, 12-Bit Serial input Digital-to-Analog Converter + * + * Copyright 2019 Qtechnology A/S + * 2019 Ricardo Ribalda <ribalda@kernel.org> + * + * 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) requires the + * transfer buffers to live in their own cache lines. + */ + uint8_t data[2] ____cacheline_aligned; +}; + +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 <ribalda@kernel.org>"); +MODULE_DESCRIPTION("Texas Instruments DAC7612 DAC driver"); +MODULE_LICENSE("GPL v2"); |