[PATCH v2 0/4] Support for analog peripherals on LPC18xx familiy

[PATCH v2 0/4] Support for analog peripherals on LPC18xx familiy

[Joachim Eastwood]

This patch set adds support for the analog (ADC and DAC) peripherals
found on NXP LPC18xx/43xx SoCs. The ADC is a SAR converter with 10-bit
resolution and 8 muxed inputs. The DAC is a simple single channel 10-
bit DAC.

Note that these drivers do not support all the features found on the
peripherals. DMA and interrupts are not supported in either drivers.
The ADC driver also lack 'burst-mode' and hardware triggers. So for
now the ADC is limited to single shot samples.

Both drivers tested on Embedded Artists' LPC4357 Developer's Kit.

Based on iio/testing branch from 29.02.15.

This version address the comments from Peter Meerwald-Stadler and
adds locking to adc read.

Changes since v1:
 - Fix nits on adc/dac from Peter Meerwald-Stadler
 - Add locking around lpc18xx_adc_read_chan()


Joachim Eastwood (4):
  iio: adc: add NXP LPC18xx ADC driver
  dt: document NXP LPC1850 ADC driver bindings
  iio: dac: add NXP LPC18xx DAC driver
  dt: document NXP LPC1850 DAC driver bindings

 .../devicetree/bindings/iio/adc/lpc1850-adc.txt    |  21 ++
 .../devicetree/bindings/iio/dac/lpc1850-dac.txt    |  20 ++
 drivers/iio/adc/Kconfig                            |  10 +
 drivers/iio/adc/Makefile                           |   1 +
 drivers/iio/adc/lpc18xx_adc.c                      | 228 +++++++++++++++++++++
 drivers/iio/dac/Kconfig                            |  10 +
 drivers/iio/dac/Makefile                           |   1 +
 drivers/iio/dac/lpc18xx_dac.c                      | 204 ++++++++++++++++++
 8 files changed, 495 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt
 create mode 100644 Documentation/devicetree/bindings/iio/dac/lpc1850-dac.txt
 create mode 100644 drivers/iio/adc/lpc18xx_adc.c
 create mode 100644 drivers/iio/dac/lpc18xx_dac.c

-- 
1.8.0

[PATCH v2 1/4] iio: adc: add NXP LPC18xx ADC driver

[Joachim Eastwood]

Add base support for the 10-bit SAR ADC peripheral found
on NXP LPC18xx/43xx SoCs.

This is a minimal driver that does not support burst mode,
interrupts, DMA or hardware triggers.

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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/iio/adc/Kconfig       |  10 ++
 drivers/iio/adc/Makefile      |   1 +
 drivers/iio/adc/lpc18xx_adc.c | 228 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 239 insertions(+)
 create mode 100644 drivers/iio/adc/lpc18xx_adc.c

diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
index 932de1f9d1e7..85994e5889ec 100644
--- a/drivers/iio/adc/Kconfig
+++ b/drivers/iio/adc/Kconfig
@@ -234,6 +234,16 @@ config LP8788_ADC
 	  To compile this driver as a module, choose M here: the module will be
 	  called lp8788_adc.
 
+config LPC18XX_ADC
+	tristate "NXP LPC18xx ADC driver"
+	depends on ARCH_LPC18XX || COMPILE_TEST
+	depends on OF && HAS_IOMEM
+	help
+	  Say yes here to build support for NXP LPC18XX ADC.
+
+	  To compile this driver as a module, choose M here: the module will be
+	  called lpc18xx_adc.
+
 config MAX1027
 	tristate "Maxim max1027 ADC driver"
 	depends on SPI
diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
index b1aa456e6af3..1a4ac4590857 100644
--- a/drivers/iio/adc/Makefile
+++ b/drivers/iio/adc/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_HI8435) += hi8435.o
 obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
 obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
 obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
+obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
 obj-$(CONFIG_MAX1027) += max1027.o
 obj-$(CONFIG_MAX1363) += max1363.o
 obj-$(CONFIG_MCP320X) += mcp320x.o
diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c
new file mode 100644
index 000000000000..fbe9b7a7e6b8
--- /dev/null
+++ b/drivers/iio/adc/lpc18xx_adc.c
@@ -0,0 +1,228 @@
+/*
+ * IIO ADC driver for NXP LPC18xx ADC
+ *
+ * Copyright (C) 2016 Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
+ *
+ * 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:
+ *  - Hardware triggers
+ *  - Burst mode
+ *  - 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/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regulator/consumer.h>
+
+/* LPC18XX ADC registers and bits */
+#define LPC18XX_ADC_CR			0x000
+#define  LPC18XX_ADC_CR_CLKDIV_SHIFT	8
+#define  LPC18XX_ADC_CR_PDN		BIT(21)
+#define  LPC18XX_ADC_CR_START_NOW	(0x1 << 24)
+#define LPC18XX_ADC_GDR			0x004
+
+/* Data register bits */
+#define LPC18XX_ADC_SAMPLE_SHIFT	6
+#define LPC18XX_ADC_SAMPLE_MASK		0x3ff
+#define LPC18XX_ADC_CONV_DONE		BIT(31)
+
+/* Clock should be 4.5 MHz or less */
+#define LPC18XX_ADC_CLK_TARGET		4500000
+
+struct lpc18xx_adc {
+	void __iomem *base;
+	struct device *dev;
+	struct clk *clk;
+	struct regulator *vref;
+	u32 cr_reg;
+};
+
+#define LPC18XX_ADC_CHAN(_idx) {				\
+	.type = IIO_VOLTAGE,					\
+	.indexed = 1,						\
+	.channel = _idx,					\
+	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
+	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
+}
+
+static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = {
+	LPC18XX_ADC_CHAN(0),
+	LPC18XX_ADC_CHAN(1),
+	LPC18XX_ADC_CHAN(2),
+	LPC18XX_ADC_CHAN(3),
+	LPC18XX_ADC_CHAN(4),
+	LPC18XX_ADC_CHAN(5),
+	LPC18XX_ADC_CHAN(6),
+	LPC18XX_ADC_CHAN(7),
+};
+
+static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch)
+{
+	int ret;
+	u32 reg;
+
+	reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW;
+	writel(reg, adc->base + LPC18XX_ADC_CR);
+
+	ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg,
+				 reg & LPC18XX_ADC_CONV_DONE, 3, 9);
+	if (ret) {
+		dev_warn(adc->dev, "adc read timed out\n");
+		return ret;
+	}
+
+	return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK;
+}
+
+static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev,
+				struct iio_chan_spec const *chan,
+				int *val, int *val2, long mask)
+{
+	struct lpc18xx_adc *adc = iio_priv(indio_dev);
+
+	switch (mask) {
+	case IIO_CHAN_INFO_RAW:
+		mutex_lock(&indio_dev->mlock);
+		*val = lpc18xx_adc_read_chan(adc, chan->channel);
+		mutex_unlock(&indio_dev->mlock);
+		if (*val < 0)
+			return *val;
+
+		return IIO_VAL_INT;
+
+	case IIO_CHAN_INFO_SCALE:
+		*val = regulator_get_voltage(adc->vref) / 1000;
+		*val2 = 10;
+
+		return IIO_VAL_FRACTIONAL_LOG2;
+	}
+
+	return -EINVAL;
+}
+
+static const struct iio_info lpc18xx_adc_info = {
+	.read_raw = lpc18xx_adc_read_raw,
+	.driver_module = THIS_MODULE,
+};
+
+static int lpc18xx_adc_probe(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev;
+	struct lpc18xx_adc *adc;
+	struct resource *res;
+	unsigned int clkdiv;
+	unsigned long rate;
+	int ret;
+
+	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
+	if (!indio_dev)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, indio_dev);
+	adc = iio_priv(indio_dev);
+	adc->dev = &pdev->dev;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	adc->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(adc->base))
+		return PTR_ERR(adc->base);
+
+	adc->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(adc->clk)) {
+		dev_err(&pdev->dev, "error getting clock\n");
+		return PTR_ERR(adc->clk);
+	}
+
+	rate = clk_get_rate(adc->clk);
+	clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
+
+	adc->vref = devm_regulator_get(&pdev->dev, "vref");
+	if (IS_ERR(adc->vref)) {
+		dev_err(&pdev->dev, "error getting regulator\n");
+		return PTR_ERR(adc->vref);
+	}
+
+	indio_dev->name = dev_name(&pdev->dev);
+	indio_dev->dev.parent = &pdev->dev;
+	indio_dev->info = &lpc18xx_adc_info;
+	indio_dev->modes = INDIO_DIRECT_MODE;
+	indio_dev->channels = lpc18xx_adc_iio_channels;
+	indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels);
+
+	ret = regulator_enable(adc->vref);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to enable regulator\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(adc->clk);
+	if (ret) {
+		dev_err(&pdev->dev, "unable to enable clock\n");
+		goto dis_reg;
+	}
+
+	adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
+			LPC18XX_ADC_CR_PDN;
+	writel(adc->cr_reg, adc->base + LPC18XX_ADC_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:
+	writel(0, adc->base + LPC18XX_ADC_CR);
+	clk_disable_unprepare(adc->clk);
+dis_reg:
+	regulator_disable(adc->vref);
+	return ret;
+}
+
+static int lpc18xx_adc_remove(struct platform_device *pdev)
+{
+	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
+	struct lpc18xx_adc *adc = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+
+	writel(0, adc->base + LPC18XX_ADC_CR);
+	clk_disable_unprepare(adc->clk);
+	regulator_disable(adc->vref);
+
+	return 0;
+}
+
+static const struct of_device_id lpc18xx_adc_match[] = {
+	{ .compatible = "nxp,lpc1850-adc" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);
+
+static struct platform_driver lpc18xx_adc_driver = {
+	.probe	= lpc18xx_adc_probe,
+	.remove	= lpc18xx_adc_remove,
+	.driver	= {
+		.name = "lpc18xx-adc",
+		.of_match_table = lpc18xx_adc_match,
+	},
+};
+module_platform_driver(lpc18xx_adc_driver);
+
+MODULE_DESCRIPTION("LPC18xx ADC driver");
+MODULE_AUTHOR("Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
+MODULE_LICENSE("GPL v2");
-- 
1.8.0

Re: [PATCH v2 1/4] iio: adc: add NXP LPC18xx ADC driver

[Jonathan Cameron]

On 06/03/16 11:13, Joachim Eastwood wrote:
> Add base support for the 10-bit SAR ADC peripheral found
> on NXP LPC18xx/43xx SoCs.
> 
> This is a minimal driver that does not support burst mode,
> interrupts, DMA or hardware triggers.
> 
> 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
Applied to the togreg branch of iio.git - initially pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan
> ---
>  drivers/iio/adc/Kconfig       |  10 ++
>  drivers/iio/adc/Makefile      |   1 +
>  drivers/iio/adc/lpc18xx_adc.c | 228 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 239 insertions(+)
>  create mode 100644 drivers/iio/adc/lpc18xx_adc.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 932de1f9d1e7..85994e5889ec 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -234,6 +234,16 @@ config LP8788_ADC
>  	  To compile this driver as a module, choose M here: the module will be
>  	  called lp8788_adc.
>  
> +config LPC18XX_ADC
> +	tristate "NXP LPC18xx ADC driver"
> +	depends on ARCH_LPC18XX || COMPILE_TEST
> +	depends on OF && HAS_IOMEM
> +	help
> +	  Say yes here to build support for NXP LPC18XX ADC.
> +
> +	  To compile this driver as a module, choose M here: the module will be
> +	  called lpc18xx_adc.
> +
>  config MAX1027
>  	tristate "Maxim max1027 ADC driver"
>  	depends on SPI
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index b1aa456e6af3..1a4ac4590857 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -24,6 +24,7 @@ obj-$(CONFIG_HI8435) += hi8435.o
>  obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
>  obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
> +obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
>  obj-$(CONFIG_MAX1027) += max1027.o
>  obj-$(CONFIG_MAX1363) += max1363.o
>  obj-$(CONFIG_MCP320X) += mcp320x.o
> diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c
> new file mode 100644
> index 000000000000..fbe9b7a7e6b8
> --- /dev/null
> +++ b/drivers/iio/adc/lpc18xx_adc.c
> @@ -0,0 +1,228 @@
> +/*
> + * IIO ADC driver for NXP LPC18xx ADC
> + *
> + * Copyright (C) 2016 Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> + *
> + * 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:
> + *  - Hardware triggers
> + *  - Burst mode
> + *  - 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/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +
> +/* LPC18XX ADC registers and bits */
> +#define LPC18XX_ADC_CR			0x000
> +#define  LPC18XX_ADC_CR_CLKDIV_SHIFT	8
> +#define  LPC18XX_ADC_CR_PDN		BIT(21)
> +#define  LPC18XX_ADC_CR_START_NOW	(0x1 << 24)
> +#define LPC18XX_ADC_GDR			0x004
> +
> +/* Data register bits */
> +#define LPC18XX_ADC_SAMPLE_SHIFT	6
> +#define LPC18XX_ADC_SAMPLE_MASK		0x3ff
> +#define LPC18XX_ADC_CONV_DONE		BIT(31)
> +
> +/* Clock should be 4.5 MHz or less */
> +#define LPC18XX_ADC_CLK_TARGET		4500000
> +
> +struct lpc18xx_adc {
> +	void __iomem *base;
> +	struct device *dev;
> +	struct clk *clk;
> +	struct regulator *vref;
> +	u32 cr_reg;
> +};
> +
> +#define LPC18XX_ADC_CHAN(_idx) {				\
> +	.type = IIO_VOLTAGE,					\
> +	.indexed = 1,						\
> +	.channel = _idx,					\
> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
> +}
> +
> +static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = {
> +	LPC18XX_ADC_CHAN(0),
> +	LPC18XX_ADC_CHAN(1),
> +	LPC18XX_ADC_CHAN(2),
> +	LPC18XX_ADC_CHAN(3),
> +	LPC18XX_ADC_CHAN(4),
> +	LPC18XX_ADC_CHAN(5),
> +	LPC18XX_ADC_CHAN(6),
> +	LPC18XX_ADC_CHAN(7),
> +};
> +
> +static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch)
> +{
> +	int ret;
> +	u32 reg;
> +
> +	reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW;
> +	writel(reg, adc->base + LPC18XX_ADC_CR);
> +
> +	ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg,
> +				 reg & LPC18XX_ADC_CONV_DONE, 3, 9);
> +	if (ret) {
> +		dev_warn(adc->dev, "adc read timed out\n");
> +		return ret;
> +	}
> +
> +	return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK;
> +}
> +
> +static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan,
> +				int *val, int *val2, long mask)
> +{
> +	struct lpc18xx_adc *adc = iio_priv(indio_dev);
> +
> +	switch (mask) {
> +	case IIO_CHAN_INFO_RAW:
> +		mutex_lock(&indio_dev->mlock);
> +		*val = lpc18xx_adc_read_chan(adc, chan->channel);
> +		mutex_unlock(&indio_dev->mlock);
> +		if (*val < 0)
> +			return *val;
> +
> +		return IIO_VAL_INT;
> +
> +	case IIO_CHAN_INFO_SCALE:
> +		*val = regulator_get_voltage(adc->vref) / 1000;
> +		*val2 = 10;
> +
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static const struct iio_info lpc18xx_adc_info = {
> +	.read_raw = lpc18xx_adc_read_raw,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +static int lpc18xx_adc_probe(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev;
> +	struct lpc18xx_adc *adc;
> +	struct resource *res;
> +	unsigned int clkdiv;
> +	unsigned long rate;
> +	int ret;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +	adc = iio_priv(indio_dev);
> +	adc->dev = &pdev->dev;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	adc->base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(adc->base))
> +		return PTR_ERR(adc->base);
> +
> +	adc->clk = devm_clk_get(&pdev->dev, NULL);
> +	if (IS_ERR(adc->clk)) {
> +		dev_err(&pdev->dev, "error getting clock\n");
> +		return PTR_ERR(adc->clk);
> +	}
> +
> +	rate = clk_get_rate(adc->clk);
> +	clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
> +
> +	adc->vref = devm_regulator_get(&pdev->dev, "vref");
> +	if (IS_ERR(adc->vref)) {
> +		dev_err(&pdev->dev, "error getting regulator\n");
> +		return PTR_ERR(adc->vref);
> +	}
> +
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->info = &lpc18xx_adc_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = lpc18xx_adc_iio_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels);
> +
> +	ret = regulator_enable(adc->vref);
> +	if (ret) {
> +		dev_err(&pdev->dev, "unable to enable regulator\n");
> +		return ret;
> +	}
> +
> +	ret = clk_prepare_enable(adc->clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "unable to enable clock\n");
> +		goto dis_reg;
> +	}
> +
> +	adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
> +			LPC18XX_ADC_CR_PDN;
> +	writel(adc->cr_reg, adc->base + LPC18XX_ADC_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:
> +	writel(0, adc->base + LPC18XX_ADC_CR);
> +	clk_disable_unprepare(adc->clk);
> +dis_reg:
> +	regulator_disable(adc->vref);
> +	return ret;
> +}
> +
> +static int lpc18xx_adc_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct lpc18xx_adc *adc = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +
> +	writel(0, adc->base + LPC18XX_ADC_CR);
> +	clk_disable_unprepare(adc->clk);
> +	regulator_disable(adc->vref);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id lpc18xx_adc_match[] = {
> +	{ .compatible = "nxp,lpc1850-adc" },
> +	{ /* sentinel */ }
> +};
> +MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);
> +
> +static struct platform_driver lpc18xx_adc_driver = {
> +	.probe	= lpc18xx_adc_probe,
> +	.remove	= lpc18xx_adc_remove,
> +	.driver	= {
> +		.name = "lpc18xx-adc",
> +		.of_match_table = lpc18xx_adc_match,
> +	},
> +};
> +module_platform_driver(lpc18xx_adc_driver);
> +
> +MODULE_DESCRIPTION("LPC18xx ADC driver");
> +MODULE_AUTHOR("Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
> +MODULE_LICENSE("GPL v2");
> 

Re: [PATCH v2 1/4] iio: adc: add NXP LPC18xx ADC driver

[Jonathan Cameron]

On 12/03/16 10:30, Jonathan Cameron wrote:
> On 06/03/16 11:13, Joachim Eastwood wrote:
>> Add base support for the 10-bit SAR ADC peripheral found
>> on NXP LPC18xx/43xx SoCs.
>>
>> This is a minimal driver that does not support burst mode,
>> interrupts, DMA or hardware triggers.
>>
>> 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> Applied to the togreg branch of iio.git - initially pushed out as testing
> for the autobuilders to play with it.
Actually I've backed this out.  Picked up on a few things lookint
at the DAC driver that apply here too.

Clearly half asleep this morning!

Sorry,

Jonathan
> 
> Thanks,
> 
> Jonathan
>> ---
>>  drivers/iio/adc/Kconfig       |  10 ++
>>  drivers/iio/adc/Makefile      |   1 +
>>  drivers/iio/adc/lpc18xx_adc.c | 228 ++++++++++++++++++++++++++++++++++++++++++
>>  3 files changed, 239 insertions(+)
>>  create mode 100644 drivers/iio/adc/lpc18xx_adc.c
>>
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index 932de1f9d1e7..85994e5889ec 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -234,6 +234,16 @@ config LP8788_ADC
>>  	  To compile this driver as a module, choose M here: the module will be
>>  	  called lp8788_adc.
>>  
>> +config LPC18XX_ADC
>> +	tristate "NXP LPC18xx ADC driver"
>> +	depends on ARCH_LPC18XX || COMPILE_TEST
>> +	depends on OF && HAS_IOMEM
>> +	help
>> +	  Say yes here to build support for NXP LPC18XX ADC.
>> +
>> +	  To compile this driver as a module, choose M here: the module will be
>> +	  called lpc18xx_adc.
>> +
>>  config MAX1027
>>  	tristate "Maxim max1027 ADC driver"
>>  	depends on SPI
>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>> index b1aa456e6af3..1a4ac4590857 100644
>> --- a/drivers/iio/adc/Makefile
>> +++ b/drivers/iio/adc/Makefile
>> @@ -24,6 +24,7 @@ obj-$(CONFIG_HI8435) += hi8435.o
>>  obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
>>  obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
>>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>> +obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
>>  obj-$(CONFIG_MAX1027) += max1027.o
>>  obj-$(CONFIG_MAX1363) += max1363.o
>>  obj-$(CONFIG_MCP320X) += mcp320x.o
>> diff --git a/drivers/iio/adc/lpc18xx_adc.c b/drivers/iio/adc/lpc18xx_adc.c
>> new file mode 100644
>> index 000000000000..fbe9b7a7e6b8
>> --- /dev/null
>> +++ b/drivers/iio/adc/lpc18xx_adc.c
>> @@ -0,0 +1,228 @@
>> +/*
>> + * IIO ADC driver for NXP LPC18xx ADC
>> + *
>> + * Copyright (C) 2016 Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> + *
>> + * 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:
>> + *  - Hardware triggers
>> + *  - Burst mode
>> + *  - 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/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regulator/consumer.h>
>> +
>> +/* LPC18XX ADC registers and bits */
>> +#define LPC18XX_ADC_CR			0x000
>> +#define  LPC18XX_ADC_CR_CLKDIV_SHIFT	8
>> +#define  LPC18XX_ADC_CR_PDN		BIT(21)
>> +#define  LPC18XX_ADC_CR_START_NOW	(0x1 << 24)
>> +#define LPC18XX_ADC_GDR			0x004
>> +
>> +/* Data register bits */
>> +#define LPC18XX_ADC_SAMPLE_SHIFT	6
>> +#define LPC18XX_ADC_SAMPLE_MASK		0x3ff
>> +#define LPC18XX_ADC_CONV_DONE		BIT(31)
>> +
>> +/* Clock should be 4.5 MHz or less */
>> +#define LPC18XX_ADC_CLK_TARGET		4500000
>> +
>> +struct lpc18xx_adc {
>> +	void __iomem *base;
>> +	struct device *dev;
>> +	struct clk *clk;
>> +	struct regulator *vref;
>> +	u32 cr_reg;
>> +};
>> +
>> +#define LPC18XX_ADC_CHAN(_idx) {				\
>> +	.type = IIO_VOLTAGE,					\
>> +	.indexed = 1,						\
>> +	.channel = _idx,					\
>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),		\
>> +	.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),	\
>> +}
>> +
>> +static const struct iio_chan_spec lpc18xx_adc_iio_channels[] = {
>> +	LPC18XX_ADC_CHAN(0),
>> +	LPC18XX_ADC_CHAN(1),
>> +	LPC18XX_ADC_CHAN(2),
>> +	LPC18XX_ADC_CHAN(3),
>> +	LPC18XX_ADC_CHAN(4),
>> +	LPC18XX_ADC_CHAN(5),
>> +	LPC18XX_ADC_CHAN(6),
>> +	LPC18XX_ADC_CHAN(7),
>> +};
>> +
>> +static int lpc18xx_adc_read_chan(struct lpc18xx_adc *adc, unsigned int ch)
>> +{
>> +	int ret;
>> +	u32 reg;
>> +
>> +	reg = adc->cr_reg | BIT(ch) | LPC18XX_ADC_CR_START_NOW;
>> +	writel(reg, adc->base + LPC18XX_ADC_CR);
>> +
>> +	ret = readl_poll_timeout(adc->base + LPC18XX_ADC_GDR, reg,
>> +				 reg & LPC18XX_ADC_CONV_DONE, 3, 9);
>> +	if (ret) {
>> +		dev_warn(adc->dev, "adc read timed out\n");
>> +		return ret;
>> +	}
>> +
>> +	return (reg >> LPC18XX_ADC_SAMPLE_SHIFT) & LPC18XX_ADC_SAMPLE_MASK;
>> +}
>> +
>> +static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev,
>> +				struct iio_chan_spec const *chan,
>> +				int *val, int *val2, long mask)
>> +{
>> +	struct lpc18xx_adc *adc = iio_priv(indio_dev);
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW:
Please use a local lock to protect channels.  The mlock is specifically
for use in protecting against moving in and out of buffered mode for
drivers in which individual reads will break buffered capture.

>> +		mutex_lock(&indio_dev->mlock);
>> +		*val = lpc18xx_adc_read_chan(adc, chan->channel);
>> +		mutex_unlock(&indio_dev->mlock);
>> +		if (*val < 0)
>> +			return *val;
>> +
>> +		return IIO_VAL_INT;
>> +
>> +	case IIO_CHAN_INFO_SCALE:
>> +		*val = regulator_get_voltage(adc->vref) / 1000;
>> +		*val2 = 10;
>> +
>> +		return IIO_VAL_FRACTIONAL_LOG2;
>> +	}
>> +
>> +	return -EINVAL;
>> +}
>> +
>> +static const struct iio_info lpc18xx_adc_info = {
>> +	.read_raw = lpc18xx_adc_read_raw,
>> +	.driver_module = THIS_MODULE,
>> +};
>> +
>> +static int lpc18xx_adc_probe(struct platform_device *pdev)
>> +{
>> +	struct iio_dev *indio_dev;
>> +	struct lpc18xx_adc *adc;
>> +	struct resource *res;
>> +	unsigned int clkdiv;
>> +	unsigned long rate;
>> +	int ret;
>> +
>> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
>> +	if (!indio_dev)
>> +		return -ENOMEM;
>> +
>> +	platform_set_drvdata(pdev, indio_dev);
>> +	adc = iio_priv(indio_dev);
>> +	adc->dev = &pdev->dev;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	adc->base = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(adc->base))
>> +		return PTR_ERR(adc->base);
>> +
>> +	adc->clk = devm_clk_get(&pdev->dev, NULL);
>> +	if (IS_ERR(adc->clk)) {
>> +		dev_err(&pdev->dev, "error getting clock\n");
>> +		return PTR_ERR(adc->clk);
>> +	}
>> +
>> +	rate = clk_get_rate(adc->clk);
>> +	clkdiv = DIV_ROUND_UP(rate, LPC18XX_ADC_CLK_TARGET);
>> +
>> +	adc->vref = devm_regulator_get(&pdev->dev, "vref");
>> +	if (IS_ERR(adc->vref)) {
>> +		dev_err(&pdev->dev, "error getting regulator\n");
>> +		return PTR_ERR(adc->vref);
>> +	}
>> +
>> +	indio_dev->name = dev_name(&pdev->dev);
>> +	indio_dev->dev.parent = &pdev->dev;
>> +	indio_dev->info = &lpc18xx_adc_info;
>> +	indio_dev->modes = INDIO_DIRECT_MODE;
>> +	indio_dev->channels = lpc18xx_adc_iio_channels;
>> +	indio_dev->num_channels = ARRAY_SIZE(lpc18xx_adc_iio_channels);
>> +
>> +	ret = regulator_enable(adc->vref);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "unable to enable regulator\n");
>> +		return ret;
>> +	}
>> +
>> +	ret = clk_prepare_enable(adc->clk);
>> +	if (ret) {
>> +		dev_err(&pdev->dev, "unable to enable clock\n");
>> +		goto dis_reg;
>> +	}
>> +
>> +	adc->cr_reg = (clkdiv << LPC18XX_ADC_CR_CLKDIV_SHIFT) |
>> +			LPC18XX_ADC_CR_PDN;
>> +	writel(adc->cr_reg, adc->base + LPC18XX_ADC_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:
>> +	writel(0, adc->base + LPC18XX_ADC_CR);
>> +	clk_disable_unprepare(adc->clk);
>> +dis_reg:
>> +	regulator_disable(adc->vref);
>> +	return ret;
>> +}
>> +
>> +static int lpc18xx_adc_remove(struct platform_device *pdev)
>> +{
>> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
>> +	struct lpc18xx_adc *adc = iio_priv(indio_dev);
>> +
>> +	iio_device_unregister(indio_dev);
>> +
>> +	writel(0, adc->base + LPC18XX_ADC_CR);
>> +	clk_disable_unprepare(adc->clk);
>> +	regulator_disable(adc->vref);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id lpc18xx_adc_match[] = {
>> +	{ .compatible = "nxp,lpc1850-adc" },
>> +	{ /* sentinel */ }
>> +};
>> +MODULE_DEVICE_TABLE(of, lpc18xx_adc_match);
>> +
>> +static struct platform_driver lpc18xx_adc_driver = {
>> +	.probe	= lpc18xx_adc_probe,
>> +	.remove	= lpc18xx_adc_remove,
>> +	.driver	= {
>> +		.name = "lpc18xx-adc",
>> +		.of_match_table = lpc18xx_adc_match,
>> +	},
>> +};
>> +module_platform_driver(lpc18xx_adc_driver);
>> +
>> +MODULE_DESCRIPTION("LPC18xx ADC driver");
>> +MODULE_AUTHOR("Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
>> +MODULE_LICENSE("GPL v2");
>>
> 
> --
> To unsubscribe from this list: send the line "unsubscribe linux-iio" in
> the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> 

Re: [PATCH v2 1/4] iio: adc: add NXP LPC18xx ADC driver

[Joachim Eastwood]

On 12 March 2016 at 11:35, Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> wrote:
> On 12/03/16 10:30, Jonathan Cameron wrote:
>> On 06/03/16 11:13, Joachim Eastwood wrote:
>>> Add base support for the 10-bit SAR ADC peripheral found
>>> on NXP LPC18xx/43xx SoCs.
>>>
>>> This is a minimal driver that does not support burst mode,
>>> interrupts, DMA or hardware triggers.
>>>
>>> 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> Applied to the togreg branch of iio.git - initially pushed out as testing
>> for the autobuilders to play with it.
> Actually I've backed this out.  Picked up on a few things lookint
> at the DAC driver that apply here too.
>
> Clearly half asleep this morning!
>
> Sorry,
>
> Jonathan
>>
>> Thanks,
>>
>> Jonathan
>>> ---
>>>  drivers/iio/adc/Kconfig       |  10 ++
>>>  drivers/iio/adc/Makefile      |   1 +
>>>  drivers/iio/adc/lpc18xx_adc.c | 228 ++++++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 239 insertions(+)
>>>  create mode 100644 drivers/iio/adc/lpc18xx_adc.c

>>> +static int lpc18xx_adc_read_raw(struct iio_dev *indio_dev,
>>> +                            struct iio_chan_spec const *chan,
>>> +                            int *val, int *val2, long mask)
>>> +{
>>> +    struct lpc18xx_adc *adc = iio_priv(indio_dev);
>>> +
>>> +    switch (mask) {
>>> +    case IIO_CHAN_INFO_RAW:
> Please use a local lock to protect channels.  The mlock is specifically
> for use in protecting against moving in and out of buffered mode for
> drivers in which individual reads will break buffered capture.

okey, got it. I'll send out a new version later today. I'll add the
lock to the dac driver as well.

Does this mean that if buffered mode support is added to the driver
I'll have to change the lock again?


regards,
Joachim Eastwood

[PATCH v2 2/4] dt: document NXP LPC1850 ADC driver bindings

[Joachim Eastwood]

Signed-off-by: Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 .../devicetree/bindings/iio/adc/lpc1850-adc.txt     | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt

diff --git a/Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt b/Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt
new file mode 100644
index 000000000000..0bcae5140bc5
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt
@@ -0,0 +1,21 @@
+NXP LPC1850 ADC bindings
+
+Required properties:
+- compatible: Should be "nxp,lpc1850-adc"
+- reg: Offset and length of the register set for the ADC device
+- interrupts: The interrupt number for the ADC device
+- clocks: The root clock of the ADC controller
+- vref-supply: The regulator supply ADC reference voltage
+- resets: phandle to reset controller and line specifier
+
+Example:
+
+adc0: adc@400e3000 {
+	compatible = "nxp,lpc1850-adc";
+	reg = <0x400e3000 0x1000>;
+	interrupts = <17>;
+	clocks = <&ccu1 CLK_APB3_ADC0>;
+	vref-supply = <&reg_vdda>;
+	resets = <&rgu 40>;
+	status = "disabled";
+};
-- 
1.8.0

Re: [PATCH v2 2/4] dt: document NXP LPC1850 ADC driver bindings

[Jonathan Cameron]

On 06/03/16 11:13, Joachim Eastwood wrote:
> Signed-off-by: Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
As this is very standard, I'm happy to take it without a device
tree ack.  I can added an ack though if anyone wants to give one!

Jonathan
> ---
>  .../devicetree/bindings/iio/adc/lpc1850-adc.txt     | 21 +++++++++++++++++++++
>  1 file changed, 21 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt b/Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt
> new file mode 100644
> index 000000000000..0bcae5140bc5
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt
> @@ -0,0 +1,21 @@
> +NXP LPC1850 ADC bindings
> +
> +Required properties:
> +- compatible: Should be "nxp,lpc1850-adc"
> +- reg: Offset and length of the register set for the ADC device
> +- interrupts: The interrupt number for the ADC device
> +- clocks: The root clock of the ADC controller
> +- vref-supply: The regulator supply ADC reference voltage
> +- resets: phandle to reset controller and line specifier
> +
> +Example:
> +
> +adc0: adc@400e3000 {
> +	compatible = "nxp,lpc1850-adc";
> +	reg = <0x400e3000 0x1000>;
> +	interrupts = <17>;
> +	clocks = <&ccu1 CLK_APB3_ADC0>;
> +	vref-supply = <&reg_vdda>;
> +	resets = <&rgu 40>;
> +	status = "disabled";
> +};
> 

[PATCH v2 3/4] iio: dac: add NXP LPC18xx DAC driver

[Joachim Eastwood]

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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 drivers/iio/dac/Kconfig       |  10 +++
 drivers/iio/dac/Makefile      |   1 +
 drivers/iio/dac/lpc18xx_dac.c | 204 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 215 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..b44d06feca8e
--- /dev/null
+++ b/drivers/iio/dac/lpc18xx_dac.c
@@ -0,0 +1,204 @@
+/*
+ * IIO DAC driver for NXP LPC18xx DAC
+ *
+ * Copyright (C) 2016 Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
+ *
+ * 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/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 clk *clk;
+	void __iomem *base;
+	struct regulator *vref;
+};
+
+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;
+		writel(reg, dac->base + LPC18XX_DAC_CR);
+		writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL);
+
+		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);
+
+	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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
+MODULE_LICENSE("GPL v2");
-- 
1.8.0

Re: [PATCH v2 3/4] iio: dac: add NXP LPC18xx DAC driver

[Jonathan Cameron]

On 06/03/16 11:13, 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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
I think you probably want some locking in the raw_write function.

Otherwise, looks good.

Jonathan
> ---
>  drivers/iio/dac/Kconfig       |  10 +++
>  drivers/iio/dac/Makefile      |   1 +
>  drivers/iio/dac/lpc18xx_dac.c | 204 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 215 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..b44d06feca8e
> --- /dev/null
> +++ b/drivers/iio/dac/lpc18xx_dac.c
> @@ -0,0 +1,204 @@
> +/*
> + * IIO DAC driver for NXP LPC18xx DAC
> + *
> + * Copyright (C) 2016 Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> + *
> + * 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/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 clk *clk;
> +	void __iomem *base;
> +	struct regulator *vref;
> +};
> +
> +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;
This double write suggests to me that we need a lock in here to prevent
possible inconsistent state.  Nothing stops two sysfs writes occuring
at the same time.

Please make it a local lock though (see comments on use of mlock in previous
review).  Put a mutex in struct lpc18xx_dac.
> +		writel(reg, dac->base + LPC18XX_DAC_CR);
> +		writel(LPC18XX_DAC_CTRL_DMA_ENA, dac->base + LPC18XX_DAC_CTRL);
> +
> +		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);
> +
> +	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-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>");
> +MODULE_LICENSE("GPL v2");
> 

[PATCH v2 4/4] dt: document NXP LPC1850 DAC driver bindings

[Joachim Eastwood]

Signed-off-by: Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
---
 .../devicetree/bindings/iio/dac/lpc1850-dac.txt      | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/dac/lpc1850-dac.txt

diff --git a/Documentation/devicetree/bindings/iio/dac/lpc1850-dac.txt b/Documentation/devicetree/bindings/iio/dac/lpc1850-dac.txt
new file mode 100644
index 000000000000..7d6647d4af5e
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/dac/lpc1850-dac.txt
@@ -0,0 +1,20 @@
+NXP LPC1850 DAC bindings
+
+Required properties:
+- compatible: Should be "nxp,lpc1850-dac"
+- reg: Offset and length of the register set for the ADC device
+- interrupts: The interrupt number for the ADC device
+- clocks: The root clock of the ADC controller
+- vref-supply: The regulator supply ADC reference voltage
+- resets: phandle to reset controller and line specifier
+
+Example:
+dac: dac@400e1000 {
+	compatible = "nxp,lpc1850-dac";
+	reg = <0x400e1000 0x1000>;
+	interrupts = <0>;
+	clocks = <&ccu1 CLK_APB3_DAC>;
+	vref-supply = <&reg_vdda>;
+	resets = <&rgu 42>;
+	status = "disabled";
+};
-- 
1.8.0

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