Date:	Tue, 12 Feb 2013 13:07:32 -0800
From:	Guenter Roeck <linux@...ck-us.net>
To:	Naveen Krishna Chatradhi <ch.naveen@...sung.com>
Cc:	linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-samsung-soc@...r.kernel.org, dianders@...omium.org,
	gregkh@...uxfoundation.org, naveenkrishna.ch@...il.com,
	lars@...afoo.de
Subject: Re: iio: adc: add exynos5 adc driver under iio framwork

On Wed, Jan 23, 2013 at 04:58:06AM -0000, Naveen Krishna Chatradhi wrote:
> This patch add an ADC IP found on EXYNOS5 series socs from Samsung.
> Also adds the Documentation for device tree bindings.
> 
> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@...sung.com>
> 
> ---
> Changes since v1:
> 
> 1. Fixed comments from Lars
> 2. Added support for ADC on EXYNOS5410
> 
> Changes since v2:
> 
> 1. Changed the instance name for (struct iio_dev *) to indio_dev
> 2. Changed devm_request_irq to request_irq
> 
> Few doubts regarding the mappings and child device handling.
> Kindly, suggest me better methods.
> 
>  .../bindings/arm/samsung/exynos5-adc.txt           |   37 ++
>  drivers/iio/adc/Kconfig                            |    7 +
>  drivers/iio/adc/Makefile                           |    1 +
>  drivers/iio/adc/exynos5_adc.c                      |  464 ++++++++++++++++++++
>  4 files changed, 509 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/arm/samsung/exynos5-adc.txt
>  create mode 100644 drivers/iio/adc/exynos5_adc.c
> 
> diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos5-adc.txt b/Documentation/devicetree/bindings/arm/samsung/exynos5-adc.txt
> new file mode 100644
> index 0000000..9a5b515
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/samsung/exynos5-adc.txt
> @@ -0,0 +1,37 @@
> +Samsung Exynos5 Analog to Digital Converter bindings
> +
> +Required properties:
> +- compatible:		Must be "samsung,exynos5250-adc" for exynos5250 controllers.
> +- reg:			Contains ADC register address range (base address and
> +			length).
> +- interrupts: 		Contains the interrupt information for the timer. The
> +			format is being dependent on which interrupt controller
> +			the Samsung device uses.
> +
> +Note: child nodes can be added for auto probing from device tree.
> +
> +Example: adding device info in dtsi file
> +
> +adc@...10000 {
> +	compatible = "samsung,exynos5250-adc";
> +	reg = <0x12D10000 0x100>;
> +	interrupts = <0 106 0>;
> +	#address-cells = <1>;
> +	#size-cells = <1>;
> +	ranges;
> +};
> +
> +
> +Example: Adding child nodes in dts file
> +
> +adc@...10000 {
> +
> +	/* NTC thermistor is a hwmon device */
> +	ncp15wb473@0 {
> +		compatible = "ntc,ncp15wb473";
> +		reg = <0x0>;
> +		pullup-uV = <1800000>;
> +		pullup-ohm = <47000>;
> +		pulldown-ohm = <0>;
> +	};
> +};

How about:

	adc: adc@...10000 {
		compatible = "samsung,exynos5250-adc";
		reg = <0x12D10000 0x100>;
		interrupts = <0 106 0>;
		#io-channel-cells = <1>;
	};

	...

	ncp15wb473@0 {
		compatible = "ntc,ncp15wb473";
		reg = <0x0>; /* is this needed ? */
		io-channels = <&adc 0>;
		io-channel-names = "adc";
		pullup-uV = <1800000>;	/* uV or uv ? */ 
		pullup-ohm = <47000>;
		pulldown-ohm = <0>;
	};

The ncp15wb473 driver would then use either iio_channel_get_all() to get the iio
channel list or, if it only supports one adc channel per instance, iio_channel_get().

In that context, it would probably make sense to rework the ntc_thermistor
driver to support both DT as well as direct instantiation using access functions
and platform data (as it does today).

Also see https://patchwork.kernel.org/patch/2112171/.

Thanks,
Guenter

> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index fe822a1..33ceabf 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -91,6 +91,13 @@ config AT91_ADC
>  	help
>  	  Say yes here to build support for Atmel AT91 ADC.
>  
> +config EXYNOS5_ADC
> +	bool "Exynos5 ADC driver support"
> +	help
> +	  Core support for the ADC block found in the Samsung EXYNOS5 series
> +	  of SoCs for drivers such as the touchscreen and hwmon to use to share
> +	  this resource.
> +
>  config LP8788_ADC
>  	bool "LP8788 ADC driver"
>  	depends on MFD_LP8788
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 2d5f100..5b4a4f6 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -10,6 +10,7 @@ obj-$(CONFIG_AD7791) += ad7791.o
>  obj-$(CONFIG_AD7793) += ad7793.o
>  obj-$(CONFIG_AD7887) += ad7887.o
>  obj-$(CONFIG_AT91_ADC) += at91_adc.o
> +obj-$(CONFIG_EXYNOS5_ADC) += exynos5_adc.o
>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>  obj-$(CONFIG_MAX1363) += max1363.o
>  obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> diff --git a/drivers/iio/adc/exynos5_adc.c b/drivers/iio/adc/exynos5_adc.c
> new file mode 100644
> index 0000000..8982675
> --- /dev/null
> +++ b/drivers/iio/adc/exynos5_adc.c
> @@ -0,0 +1,464 @@
> +/*
> + *  exynos5_adc.c - Support for ADC in EXYNOS5 SoCs
> + *
> + *  8 ~ 10 channel, 10/12-bit ADC
> + *
> + *  Copyright (C) 2013 Naveen Krishna Chatradhi <ch.naveen@...sung.com>
> + *
> + *  This program is free software; you can redistribute it and/or modify
> + *  it under the terms of the GNU General Public License as published by
> + *  the Free Software Foundation; either version 2 of the License, or
> + *  (at your option) any later version.
> + *
> + *  This program is distributed in the hope that it will be useful,
> + *  but WITHOUT ANY WARRANTY; without even the implied warranty of
> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + *  GNU General Public License for more details.
> + *
> + *  You should have received a copy of the GNU General Public License
> + *  along with this program; if not, write to the Free Software
> + *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
> + */
> +
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/kernel.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/clk.h>
> +#include <linux/completion.h>
> +#include <linux/of.h>
> +#include <linux/of_irq.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/of_platform.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/machine.h>
> +#include <linux/iio/driver.h>
> +
> +enum adc_version {
> +	ADC_V1,
> +	ADC_V2
> +};
> +
> +/* EXYNOS5250 ADC_V1 registers definitions */
> +#define ADC_V1_CON(x)		((x) + 0x00)
> +#define ADC_V1_DLY(x)		((x) + 0x08)
> +#define ADC_V1_DATX(x)		((x) + 0x0C)
> +#define ADC_V1_INTCLR(x)	((x) + 0x18)
> +#define ADC_V1_MUX(x)		((x) + 0x1c)
> +
> +/* EXYNOS5410 ADC_V2 registers definitions */
> +#define ADC_V2_CON1(x)		((x) + 0x00)
> +#define ADC_V2_CON2(x)		((x) + 0x04)
> +#define ADC_V2_STAT(x)		((x) + 0x08)
> +#define ADC_V2_INT_EN(x)	((x) + 0x10)
> +#define ADC_V2_INT_ST(x)	((x) + 0x14)
> +#define ADC_V2_VER(x)		((x) + 0x20)
> +
> +/* Bit definitions for ADC_V1 */
> +#define ADC_V1_CON_RES		(1u << 16)
> +#define ADC_V1_CON_PRSCEN	(1u << 14)
> +#define ADC_V1_CON_PRSCLV(x)	(((x) & 0xFF) << 6)
> +#define ADC_V1_CON_STANDBY	(1u << 2)
> +
> +/* Bit definitions for ADC_V2 */
> +#define ADC_V2_CON1_SOFT_RESET	(1u << 2)
> +
> +#define ADC_V2_CON2_OSEL	(1u << 10)
> +#define ADC_V2_CON2_ESEL	(1u << 9)
> +#define ADC_V2_CON2_HIGHF	(1u << 8)
> +#define ADC_V2_CON2_C_TIME(x)	(((x) & 7) << 4)
> +#define ADC_V2_CON2_ACH_SEL(x)	(((x) & 0xF) << 0)
> +#define ADC_V2_CON2_ACH_MASK	0xF
> +
> +/* Bit definitions common for ADC_V1 and ADC_V2 */
> +#define ADC_V1_CON_EN_START		(1u << 0)
> +#define ADC_V1_DATX_MASK	0xFFF
> +
> +struct exynos5_adc {
> +	void __iomem		*regs;
> +	struct clk		*clk;
> +	unsigned int		irq;
> +	struct regulator	*vdd;
> +
> +	struct completion	completion;
> +
> +	struct iio_map		*map;
> +	u32			value;
> +	unsigned int            version;
> +};
> +
> +static const struct of_device_id exynos5_adc_match[] = {
> +	{ .compatible = "samsung,exynos5250-adc", .data = (void *)ADC_V1 },
> +	{ .compatible = "samsung,exynos5410-adc", .data = (void *)ADC_V2 },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, exynos5_adc_match);
> +
> +static inline unsigned int exynos5_adc_get_version(struct platform_device *pdev)
> +{
> +	const struct of_device_id *match;
> +
> +	match = of_match_node(exynos5_adc_match, pdev->dev.of_node);
> +	return (unsigned int)match->data;
> +}
> +
> +/* default maps used by iio consumer (ex: ntc-thermistor driver) */
> +static struct iio_map exynos5_adc_iio_maps[] = {
> +	{
> +		.consumer_dev_name = "0.ncp15wb473",
> +		.consumer_channel = "adc3",
> +		.adc_channel_label = "adc3",
> +	},
> +	{
> +		.consumer_dev_name = "1.ncp15wb473",
> +		.consumer_channel = "adc4",
> +		.adc_channel_label = "adc4",
> +	},
> +	{
> +		.consumer_dev_name = "2.ncp15wb473",
> +		.consumer_channel = "adc5",
> +		.adc_channel_label = "adc5",
> +	},
> +	{
> +		.consumer_dev_name = "3.ncp15wb473",
> +		.consumer_channel = "adc6",
> +		.adc_channel_label = "adc6",
> +	},
> +	{},
> +};
> +
> +static int exynos5_read_raw(struct iio_dev *indio_dev,
> +				struct iio_chan_spec const *chan,
> +				int *val,
> +				int *val2,
> +				long mask)
> +{
> +	struct exynos5_adc *info = iio_priv(indio_dev);
> +	u32 con1, con2;
> +
> +	if (mask == IIO_CHAN_INFO_RAW) {
> +		mutex_lock(&indio_dev->mlock);
> +
> +		/* Select the channel to be used and Trigger conversion */
> +		if (info->version == ADC_V2) {
> +			con2 = readl(ADC_V2_CON2(info->regs));
> +			con2 &= ~ADC_V2_CON2_ACH_MASK;
> +			con2 |= ADC_V2_CON2_ACH_SEL(chan->address);
> +			writel(con2, ADC_V2_CON2(info->regs));
> +
> +			con1 = readl(ADC_V2_CON1(info->regs));
> +			writel(con1 | ADC_V1_CON_EN_START,
> +					ADC_V2_CON1(info->regs));
> +		} else {
> +			writel(chan->address, ADC_V1_MUX(info->regs));
> +
> +			con1 = readl(ADC_V1_CON(info->regs));
> +			writel(con1 | ADC_V1_CON_EN_START,
> +					ADC_V1_CON(info->regs));
> +		}
> +
> +		wait_for_completion(&info->completion);
> +		*val = info->value;
> +
> +		mutex_unlock(&indio_dev->mlock);
> +
> +		return IIO_VAL_INT;
> +	}
> +
> +	return -EINVAL;
> +}
> +
> +static irqreturn_t exynos5_adc_isr(int irq, void *dev_id)
> +{
> +	struct exynos5_adc *info = (struct exynos5_adc *)dev_id;
> +
> +	/* Read value */
> +	info->value = readl(ADC_V1_DATX(info->regs)) &
> +						ADC_V1_DATX_MASK;
> +	/* clear irq */
> +	if (info->version == ADC_V2)
> +		writel(1, ADC_V2_INT_ST(info->regs));
> +	else
> +		writel(1, ADC_V1_INTCLR(info->regs));
> +
> +	complete(&info->completion);
> +
> +	return IRQ_HANDLED;
> +}
> +
> +static int exynos5_adc_reg_access(struct iio_dev *indio_dev,
> +			      unsigned reg, unsigned writeval,
> +			      unsigned *readval)
> +{
> +	struct exynos5_adc *info = iio_priv(indio_dev);
> +	u32 ret;
> +
> +	mutex_lock(&indio_dev->mlock);
> +
> +	if (readval != NULL) {
> +		ret = readl(info->regs + reg);
> +		*readval = ret;
> +	} else
> +		ret = -EINVAL;
> +
> +	mutex_unlock(&indio_dev->mlock);
> +
> +	return ret;
> +}
> +
> +static const struct iio_info exynos5_adc_iio_info = {
> +	.read_raw = &exynos5_read_raw,
> +	.debugfs_reg_access = &exynos5_adc_reg_access,
> +	.driver_module = THIS_MODULE,
> +};
> +
> +#define ADC_V1_CHANNEL(_index, _id) {		\
> +	.type = IIO_VOLTAGE,				\
> +	.indexed = 1,					\
> +	.channel = _index,				\
> +	.address = _index,				\
> +	.info_mask = IIO_CHAN_INFO_RAW_SEPARATE_BIT,	\
> +	.datasheet_name = _id,				\
> +}
> +
> +/** ADC core in EXYNOS5410 has 10 channels,
> + * ADC core in EXYNOS5250 has 8 channels
> +*/
> +static const struct iio_chan_spec exynos5_adc_iio_channels[] = {
> +	ADC_V1_CHANNEL(0, "adc0"),
> +	ADC_V1_CHANNEL(1, "adc1"),
> +	ADC_V1_CHANNEL(2, "adc2"),
> +	ADC_V1_CHANNEL(3, "adc3"),
> +	ADC_V1_CHANNEL(4, "adc4"),
> +	ADC_V1_CHANNEL(5, "adc5"),
> +	ADC_V1_CHANNEL(6, "adc6"),
> +	ADC_V1_CHANNEL(7, "adc7"),
> +	ADC_V1_CHANNEL(8, "adc8"),
> +	ADC_V1_CHANNEL(9, "adc9"),
> +};
> +
> +static int exynos5_adc_remove_devices(struct device *dev, void *c)
> +{
> +	struct platform_device *pdev = to_platform_device(dev);
> +
> +	platform_device_unregister(pdev);
> +
> +	return 0;
> +}
> +
> +static void exynos5_adc_hw_init(struct exynos5_adc *info)
> +{
> +	u32 con1, con2;
> +
> +	if (info->version == ADC_V2) {
> +		con1 = ADC_V2_CON1_SOFT_RESET;
> +		writel(con1, ADC_V2_CON1(info->regs));
> +
> +		con2 = ADC_V2_CON2_OSEL | ADC_V2_CON2_ESEL |
> +			ADC_V2_CON2_HIGHF | ADC_V2_CON2_C_TIME(0);
> +		writel(con2, ADC_V2_CON2(info->regs));
> +
> +		/* Enable interrupts */
> +		writel(1, ADC_V2_INT_EN(info->regs));
> +	} else {
> +		/* set default prescaler values and Enable prescaler */
> +		con1 =  ADC_V1_CON_PRSCLV(49) | ADC_V1_CON_PRSCEN;
> +
> +		/* Enable 12-bit ADC resolution */
> +		con1 |= ADC_V1_CON_RES;
> +		writel(con1, ADC_V1_CON(info->regs));
> +	}
> +}
> +
> +static int exynos5_adc_probe(struct platform_device *pdev)
> +{
> +	struct exynos5_adc *info = NULL;
> +	struct device_node *np = pdev->dev.of_node;
> +	struct iio_dev *indio_dev = NULL;
> +	struct resource	*mem;
> +	int ret = -ENODEV;
> +	int irq;
> +
> +	if (!np)
> +		return ret;
> +
> +	indio_dev = iio_device_alloc(sizeof(struct exynos5_adc));
> +	if (!indio_dev) {
> +		dev_err(&pdev->dev, "failed allocating iio device\n");
> +		return -ENOMEM;
> +	}
> +
> +	info = iio_priv(indio_dev);
> +
> +	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +
> +	info->regs = devm_request_and_ioremap(&pdev->dev, mem);
> +
> +	irq = platform_get_irq(pdev, 0);
> +	if (irq < 0) {
> +		dev_err(&pdev->dev, "no irq resource?\n");
> +		ret = irq;
> +		goto err_iio;
> +	}
> +
> +	info->irq = irq;
> +
> +	ret = request_irq(info->irq, exynos5_adc_isr,
> +					0, dev_name(&pdev->dev), info);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed requesting irq, irq = %d\n",
> +							info->irq);
> +		goto err_iio;
> +	}
> +
> +	info->clk = devm_clk_get(&pdev->dev, "adc");
> +	if (IS_ERR(info->clk)) {
> +		dev_err(&pdev->dev, "failed getting clock, err = %ld\n",
> +							PTR_ERR(info->clk));
> +		ret = PTR_ERR(info->clk);
> +		goto err_irq;
> +	}
> +
> +	info->vdd = devm_regulator_get(&pdev->dev, "vdd");
> +	if (IS_ERR(info->vdd)) {
> +		dev_err(&pdev->dev, "failed getting regulator, err = %ld\n",
> +							PTR_ERR(info->vdd));
> +		ret = PTR_ERR(info->vdd);
> +		goto err_irq;
> +	}
> +
> +	info->version = exynos5_adc_get_version(pdev);
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	init_completion(&info->completion);
> +
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->dev.of_node = pdev->dev.of_node;
> +	indio_dev->info = &exynos5_adc_iio_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = exynos5_adc_iio_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(exynos5_adc_iio_channels);
> +
> +	info->map = exynos5_adc_iio_maps;
> +
> +	ret = iio_map_array_register(indio_dev, info->map);
> +	if (ret) {
> +		dev_err(&indio_dev->dev, "failed mapping iio, err: %d\n", ret);
> +		goto err_irq;
> +	}
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret)
> +		goto err_map;
> +
> +	ret = regulator_enable(info->vdd);
> +	if (ret)
> +		goto err_iio_dev;
> +
> +	clk_prepare_enable(info->clk);
> +
> +	exynos5_adc_hw_init(info);
> +
> +	ret = of_platform_populate(np, exynos5_adc_match, NULL, &pdev->dev);
> +	if (ret < 0) {
> +		dev_err(&pdev->dev, "failed adding child nodes\n");
> +		goto err_of_populate;
> +	}
> +
> +	return 0;
> +
> +err_of_populate:
> +	device_for_each_child(&pdev->dev, NULL, exynos5_adc_remove_devices);
> +err_iio_dev:
> +	iio_device_unregister(indio_dev);
> +err_map:
> +	iio_map_array_unregister(indio_dev, info->map);
> +err_irq:
> +	free_irq(info->irq, info);
> +err_iio:
> +	iio_device_free(indio_dev);
> +	return ret;
> +}
> +
> +static int exynos5_adc_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct exynos5_adc *info = iio_priv(indio_dev);
> +
> +	iio_device_unregister(indio_dev);
> +	iio_map_array_unregister(indio_dev, info->map);
> +	free_irq(info->irq, info);
> +	iio_device_free(indio_dev);
> +
> +	return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int exynos5_adc_suspend(struct device *dev)
> +{
> +	struct exynos5_adc *info = dev_get_data(dev);
> +	u32 con;
> +
> +	if (info->version == ADC_V2) {
> +		con = readl(ADC_V2_CON1(info->regs));
> +		con &= ~ADC_V1_CON_EN_START;
> +		writel(con, ADC_V2_CON1(info->regs));
> +	} else {
> +		con = readl(ADC_V1_CON(info->regs));
> +		con |= ADC_V1_CON_STANDBY;
> +		writel(con, ADC_V1_CON(info->regs));
> +	}
> +
> +	clk_unprepare_disable(info->clk);
> +	regulator_disable(info->vdd);
> +
> +	return 0;
> +}
> +
> +static int exynos5_adc_resume(struct device *dev)
> +{
> +	struct exynos5_adc *info = dev_get_data(dev);
> +	int ret;
> +
> +	ret = regulator_enable(info->vdd);
> +	if (ret)
> +		return ret;
> +
> +	clk_prepare_enable(info->clk);
> +
> +	exynos5_adc_hw_init(info);
> +
> +	return 0;
> +}
> +
> +#else
> +#define exynos5_adc_suspend NULL
> +#define exynos5_adc_resume NULL
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(exynos5_adc_pm_ops,
> +			exynos5_adc_suspend,
> +			exynos5_adc_resume);
> +
> +static struct platform_driver exynos5_adc_driver = {
> +	.probe		= exynos5_adc_probe,
> +	.remove		= exynos5_adc_remove,
> +	.driver		= {
> +		.name	= "exynos5-adc",
> +		.owner	= THIS_MODULE,
> +		.of_match_table = of_match_ptr(exynos5_adc_match),
> +		.pm	= &exynos5_adc_pm_ops,
> +	},
> +};
> +
> +module_platform_driver(exynos5_adc_driver);
> +
> +MODULE_AUTHOR("Naveen Krishna Chatradhi <ch.naveen@...sung.com>");
> +MODULE_DESCRIPTION("Samsung EXYNOS5 ADC driver");
> +MODULE_LICENSE("GPL");
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