diff options
Diffstat (limited to 'drivers/iio/dac/lpc18xx_dac.c')
| -rw-r--r-- | drivers/iio/dac/lpc18xx_dac.c | 200 |
1 files changed, 200 insertions, 0 deletions
diff --git a/drivers/iio/dac/lpc18xx_dac.c b/drivers/iio/dac/lpc18xx_dac.c new file mode 100644 index 000000000..60467c6f2 --- /dev/null +++ b/drivers/iio/dac/lpc18xx_dac.c @@ -0,0 +1,200 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * IIO DAC driver for NXP LPC18xx DAC + * + * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com> + * + * UNSUPPORTED hardware features: + * - Interrupts + * - DMA + */ + +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/iio/iio.h> +#include <linux/iio/driver.h> +#include <linux/io.h> +#include <linux/iopoll.h> +#include <linux/module.h> +#include <linux/mod_devicetable.h> +#include <linux/mutex.h> +#include <linux/platform_device.h> +#include <linux/regulator/consumer.h> + +/* LPC18XX DAC registers and bits */ +#define LPC18XX_DAC_CR 0x000 +#define LPC18XX_DAC_CR_VALUE_SHIFT 6 +#define LPC18XX_DAC_CR_VALUE_MASK 0x3ff +#define LPC18XX_DAC_CR_BIAS BIT(16) +#define LPC18XX_DAC_CTRL 0x004 +#define LPC18XX_DAC_CTRL_DMA_ENA BIT(3) + +struct lpc18xx_dac { + struct regulator *vref; + void __iomem *base; + struct mutex lock; + struct clk *clk; +}; + +static const struct iio_chan_spec lpc18xx_dac_iio_channels[] = { + { + .type = IIO_VOLTAGE, + .output = 1, + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | + BIT(IIO_CHAN_INFO_SCALE), + }, +}; + +static int lpc18xx_dac_read_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int *val, int *val2, long mask) +{ + struct lpc18xx_dac *dac = iio_priv(indio_dev); + u32 reg; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + reg = readl(dac->base + LPC18XX_DAC_CR); + *val = reg >> LPC18XX_DAC_CR_VALUE_SHIFT; + *val &= LPC18XX_DAC_CR_VALUE_MASK; + + return IIO_VAL_INT; + + case IIO_CHAN_INFO_SCALE: + *val = regulator_get_voltage(dac->vref) / 1000; + *val2 = 10; + + return IIO_VAL_FRACTIONAL_LOG2; + } + + return -EINVAL; +} + +static int lpc18xx_dac_write_raw(struct iio_dev *indio_dev, + struct iio_chan_spec const *chan, + int val, int val2, long mask) +{ + struct lpc18xx_dac *dac = iio_priv(indio_dev); + u32 reg; + + switch (mask) { + case IIO_CHAN_INFO_RAW: + if (val < 0 || val > LPC18XX_DAC_CR_VALUE_MASK) + return -EINVAL; + + reg = LPC18XX_DAC_CR_BIAS; + reg |= val << LPC18XX_DAC_CR_VALUE_SHIFT; + + mutex_lock(&dac->lock); + writel(reg, dac->base + LPC18XX_DAC_CR); + writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL); + mutex_unlock(&dac->lock); + + return 0; + } + + return -EINVAL; +} + +static const struct iio_info lpc18xx_dac_info = { + .read_raw = lpc18xx_dac_read_raw, + .write_raw = lpc18xx_dac_write_raw, +}; + +static int lpc18xx_dac_probe(struct platform_device *pdev) +{ + struct iio_dev *indio_dev; + struct lpc18xx_dac *dac; + int ret; + + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*dac)); + if (!indio_dev) + return -ENOMEM; + + platform_set_drvdata(pdev, indio_dev); + dac = iio_priv(indio_dev); + mutex_init(&dac->lock); + + dac->base = devm_platform_ioremap_resource(pdev, 0); + if (IS_ERR(dac->base)) + return PTR_ERR(dac->base); + + dac->clk = devm_clk_get(&pdev->dev, NULL); + if (IS_ERR(dac->clk)) + return dev_err_probe(&pdev->dev, PTR_ERR(dac->clk), + "error getting clock\n"); + + dac->vref = devm_regulator_get(&pdev->dev, "vref"); + if (IS_ERR(dac->vref)) + return dev_err_probe(&pdev->dev, PTR_ERR(dac->vref), + "error getting regulator\n"); + + indio_dev->name = dev_name(&pdev->dev); + indio_dev->info = &lpc18xx_dac_info; + indio_dev->modes = INDIO_DIRECT_MODE; + indio_dev->channels = lpc18xx_dac_iio_channels; + indio_dev->num_channels = ARRAY_SIZE(lpc18xx_dac_iio_channels); + + ret = regulator_enable(dac->vref); + if (ret) { + dev_err(&pdev->dev, "unable to enable regulator\n"); + return ret; + } + + ret = clk_prepare_enable(dac->clk); + if (ret) { + dev_err(&pdev->dev, "unable to enable clock\n"); + goto dis_reg; + } + + writel(0, dac->base + LPC18XX_DAC_CTRL); + writel(0, dac->base + LPC18XX_DAC_CR); + + ret = iio_device_register(indio_dev); + if (ret) { + dev_err(&pdev->dev, "unable to register device\n"); + goto dis_clk; + } + + return 0; + +dis_clk: + clk_disable_unprepare(dac->clk); +dis_reg: + regulator_disable(dac->vref); + return ret; +} + +static int lpc18xx_dac_remove(struct platform_device *pdev) +{ + struct iio_dev *indio_dev = platform_get_drvdata(pdev); + struct lpc18xx_dac *dac = iio_priv(indio_dev); + + iio_device_unregister(indio_dev); + + writel(0, dac->base + LPC18XX_DAC_CTRL); + clk_disable_unprepare(dac->clk); + regulator_disable(dac->vref); + + return 0; +} + +static const struct of_device_id lpc18xx_dac_match[] = { + { .compatible = "nxp,lpc1850-dac" }, + { /* sentinel */ } +}; +MODULE_DEVICE_TABLE(of, lpc18xx_dac_match); + +static struct platform_driver lpc18xx_dac_driver = { + .probe = lpc18xx_dac_probe, + .remove = lpc18xx_dac_remove, + .driver = { + .name = "lpc18xx-dac", + .of_match_table = lpc18xx_dac_match, + }, +}; +module_platform_driver(lpc18xx_dac_driver); + +MODULE_DESCRIPTION("LPC18xx DAC driver"); +MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>"); +MODULE_LICENSE("GPL v2"); |