Re: [PATCH v3 3/4] iio: dac: add NXP LPC18xx DAC driver

[Jonathan Cameron <jic23@kernel.org>]

On 12/03/16 12:30, Joachim Eastwood wrote:
> Add base support for the 10-bit DAC peripheral found
> on NXP LPC18xx/43xx SoCs.
> 
> This is a minimal driver that does not support DMA or
> interrupts.
> 
> User manual with register description can be found on:
> LPC18xx: www.nxp.com/documents/user_manual/UM10430.pdf
> LPC43xx: www.nxp.com/documents/user_manual/UM10503.pdf
> 
> Signed-off-by: Joachim Eastwood <manabian@gmail.com>
Applied.
> ---
>  drivers/iio/dac/Kconfig       |  10 ++
>  drivers/iio/dac/Makefile      |   1 +
>  drivers/iio/dac/lpc18xx_dac.c | 210 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 221 insertions(+)
>  create mode 100644 drivers/iio/dac/lpc18xx_dac.c
> 
> diff --git a/drivers/iio/dac/Kconfig b/drivers/iio/dac/Kconfig
> index a995139f907c..210db81ca144 100644
> --- a/drivers/iio/dac/Kconfig
> +++ b/drivers/iio/dac/Kconfig
> @@ -154,6 +154,16 @@ config AD7303
>  	  To compile this driver as module choose M here: the module will be called
>  	  ad7303.
>  
> +config LPC18XX_DAC
> +	tristate "NXP LPC18xx DAC driver"
> +	depends on ARCH_LPC18XX || COMPILE_TEST
> +	depends on OF && HAS_IOMEM
> +	help
> +	  Say yes here to build support for NXP LPC18XX DAC.
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called lpc18xx_dac.
> +
>  config M62332
>  	tristate "Mitsubishi M62332 DAC driver"
>  	depends on I2C
> diff --git a/drivers/iio/dac/Makefile b/drivers/iio/dac/Makefile
> index 67b48429686d..420a15cdaa53 100644
> --- a/drivers/iio/dac/Makefile
> +++ b/drivers/iio/dac/Makefile
> @@ -17,6 +17,7 @@ obj-$(CONFIG_AD5764) += ad5764.o
>  obj-$(CONFIG_AD5791) += ad5791.o
>  obj-$(CONFIG_AD5686) += ad5686.o
>  obj-$(CONFIG_AD7303) += ad7303.o
> +obj-$(CONFIG_LPC18XX_DAC) += lpc18xx_dac.o
>  obj-$(CONFIG_M62332) += m62332.o
>  obj-$(CONFIG_MAX517) += max517.o
>  obj-$(CONFIG_MAX5821) += max5821.o
> diff --git a/drivers/iio/dac/lpc18xx_dac.c b/drivers/iio/dac/lpc18xx_dac.c
> new file mode 100644
> index 000000000000..55d1456a059d
> --- /dev/null
> +++ b/drivers/iio/dac/lpc18xx_dac.c
> @@ -0,0 +1,210 @@
> +/*
> + * IIO DAC driver for NXP LPC18xx DAC
> + *
> + * Copyright (C) 2016 Joachim Eastwood <manabian@gmail.com>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * 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/mutex.h>
> +#include <linux/of.h>
> +#include <linux/of_device.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,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int lpc18xx_dac_probe(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev;
> +	struct lpc18xx_dac *dac;
> +	struct resource *res;
> +	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);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	dac->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(dac->base))
> +		return PTR_ERR(dac->base);
> +
> +	dac->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(dac->clk)) {
> +		dev_err(&pdev->dev, "error getting clock\n");
> +		return PTR_ERR(dac->clk);
> +	}
> +
> +	dac->vref = devm_regulator_get(&pdev->dev, "vref");
> +	if (IS_ERR(dac->vref)) {
> +		dev_err(&pdev->dev, "error getting regulator\n");
> +		return PTR_ERR(dac->vref);
> +	}
> +
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->dev.parent = &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");
>