[v2,1/3] dt-bindings: iio/adc: Add docs for Ingenic JZ47xx SoCs ADC.

Message ID 20190204001514.29891-1-contact@artur-rojek.eu
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  • [v2,1/3] dt-bindings: iio/adc: Add docs for Ingenic JZ47xx SoCs ADC.
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Commit Message

Artur Rojek Feb. 4, 2019, 12:15 a.m.
Add documentation for the ADC controller on JZ47xx SoCs,
used by the ingenic-adc driver.

Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
---

 Changes:

 v2: change a typo ',' into ';' in battery example

 .../bindings/iio/adc/ingenic,adc.txt          | 48 +++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt

Comments

Jonathan Cameron Feb. 9, 2019, 3:38 p.m. | #1
On Mon,  4 Feb 2019 01:15:12 +0100
Artur Rojek <contact@artur-rojek.eu> wrote:

> Add documentation for the ADC controller on JZ47xx SoCs,
> used by the ingenic-adc driver.
> 
> Signed-off-by: Artur Rojek <contact@artur-rojek.eu>

Hi,

This one seems simple enough and entirely standard that I'll take
it without a dt review.  As ever one is welcome, but feels like
it would be wasting Rob / Mark or anyone elses time!

Applied to the togreg branch of iio.git and pushed out as testing
for the autobuilders to play with it.

Thanks,

Jonathan

> ---
> 
>  Changes:
> 
>  v2: change a typo ',' into ';' in battery example
> 
>  .../bindings/iio/adc/ingenic,adc.txt          | 48 +++++++++++++++++++
>  1 file changed, 48 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt
> 
> diff --git a/Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt b/Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt
> new file mode 100644
> index 000000000000..f01159f20d87
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt
> @@ -0,0 +1,48 @@
> +* Ingenic JZ47xx ADC controller IIO bindings
> +
> +Required properties:
> +
> +- compatible: Should be one of:
> +  * ingenic,jz4725b-adc
> +  * ingenic,jz4740-adc
> +- reg: ADC controller registers location and length.
> +- clocks: phandle to the SoC's ADC clock.
> +- clock-names: Must be set to "adc".
> +- #io-channel-cells: Must be set to <1> to indicate channels are selected
> +  by index.
> +
> +ADC clients must use the format described in iio-bindings.txt, giving
> +a phandle and IIO specifier pair ("io-channels") to the ADC controller.
> +
> +Example:
> +
> +#include <dt-bindings/iio/adc/ingenic,adc.h>
> +
> +adc: adc@10070000 {
> +	compatible = "ingenic,jz4740-adc";
> +	#io-channel-cells = <1>;
> +
> +	reg = <0x10070000 0x30>;
> +
> +	clocks = <&cgu JZ4740_CLK_ADC>;
> +	clock-names = "adc";
> +
> +	interrupt-parent = <&intc>;
> +	interrupts = <18>;
> +};
> +
> +adc-keys {
> +	...
> +	compatible = "adc-keys";
> +	io-channels = <&adc INGENIC_ADC_AUX>;
> +	io-channel-names = "buttons";
> +	...
> +};
> +
> +battery {
> +	...
> +	compatible = "ingenic,jz4740-battery";
> +	io-channels = <&adc INGENIC_ADC_BATTERY>;
> +	io-channel-names = "battery";
> +	...
> +};
Jonathan Cameron Feb. 9, 2019, 3:39 p.m. | #2
On Mon,  4 Feb 2019 01:15:14 +0100
Artur Rojek <contact@artur-rojek.eu> wrote:

> Add an IIO driver for the ADC hardware present on Ingenic JZ47xx SoCs.
> 
> Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
Applied to the togreg branch of iio.git and pushed out as testing for
the autobuilders to play with it.

One note inline, but more for something general we should tidy up
than a change in this driver!

Thanks,

Jonathan

> ---
> 
>  Changes:
> 
>  v2: - prefix all platform defines with JZ_ADC_*,
>      - replace spinlock with a mutex,
>      - change devm_add_action to devm_add_action_or_reset,
>      - add a function wrapper for clk_unprepare,
>      - change iio_dev->name from "adc" to "jz-adc",
>      - simplify error handling code for devm_iio_device_register
> 
>  drivers/iio/adc/Kconfig       |   9 +
>  drivers/iio/adc/Makefile      |   1 +
>  drivers/iio/adc/ingenic-adc.c | 363 ++++++++++++++++++++++++++++++++++
>  3 files changed, 373 insertions(+)
>  create mode 100644 drivers/iio/adc/ingenic-adc.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 7a3ca4ec0cb7..f9f349a22b04 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -367,6 +367,15 @@ config INA2XX_ADC
>  	  Say yes here to build support for TI INA2xx family of Power Monitors.
>  	  This driver is mutually exclusive with the HWMON version.
>  
> +config INGENIC_ADC
> +	tristate "Ingenic JZ47xx SoCs ADC driver"
> +	depends on MIPS || COMPILE_TEST
> +	help
> +	  Say yes here to build support for the Ingenic JZ47xx SoCs ADC unit.
> +
> +	  This driver can also be built as a module. If so, the module will be
> +	  called ingenic_adc.
> +
>  config IMX7D_ADC
>  	tristate "Freescale IMX7D ADC driver"
>  	depends on ARCH_MXC || COMPILE_TEST
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 07df37f621bd..0a7acab33b91 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -36,6 +36,7 @@ obj-$(CONFIG_HI8435) += hi8435.o
>  obj-$(CONFIG_HX711) += hx711.o
>  obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
>  obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
> +obj-$(CONFIG_INGENIC_ADC) += ingenic-adc.o
>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>  obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
>  obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
> diff --git a/drivers/iio/adc/ingenic-adc.c b/drivers/iio/adc/ingenic-adc.c
> new file mode 100644
> index 000000000000..1f436df1fd45
> --- /dev/null
> +++ b/drivers/iio/adc/ingenic-adc.c
> @@ -0,0 +1,363 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * ADC driver for the Ingenic JZ47xx SoCs
> + * Copyright (c) 2019 Artur Rojek <contact@artur-rojek.eu>
> + *
> + * based on drivers/mfd/jz4740-adc.c
> + */
> +
> +#include <dt-bindings/iio/adc/ingenic,adc.h>
> +#include <linux/clk.h>
> +#include <linux/iio/iio.h>
> +#include <linux/io.h>
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +
> +#define JZ_ADC_REG_ENABLE		0x00
> +#define JZ_ADC_REG_CFG			0x04
> +#define JZ_ADC_REG_CTRL			0x08
> +#define JZ_ADC_REG_STATUS		0x0c
> +#define JZ_ADC_REG_ADTCH		0x18
> +#define JZ_ADC_REG_ADBDAT		0x1c
> +#define JZ_ADC_REG_ADSDAT		0x20
> +
> +#define JZ_ADC_REG_CFG_BAT_MD		BIT(4)
> +
> +#define JZ_ADC_AUX_VREF				3300
> +#define JZ_ADC_AUX_VREF_BITS			12
> +#define JZ_ADC_BATTERY_LOW_VREF			2500
> +#define JZ_ADC_BATTERY_LOW_VREF_BITS		12
> +#define JZ4725B_ADC_BATTERY_HIGH_VREF		7500
> +#define JZ4725B_ADC_BATTERY_HIGH_VREF_BITS	10
> +#define JZ4740_ADC_BATTERY_HIGH_VREF		(7500 * 0.986)
> +#define JZ4740_ADC_BATTERY_HIGH_VREF_BITS	12
> +
> +struct ingenic_adc_soc_data {
> +	unsigned int battery_high_vref;
> +	unsigned int battery_high_vref_bits;
> +	const int *battery_raw_avail;
> +	size_t battery_raw_avail_size;
> +	const int *battery_scale_avail;
> +	size_t battery_scale_avail_size;
> +};
> +
> +struct ingenic_adc {
> +	void __iomem *base;
> +	struct clk *clk;
> +	struct mutex lock;
> +	const struct ingenic_adc_soc_data *soc_data;
> +	bool low_vref_mode;
> +};
> +
> +static void ingenic_adc_set_config(struct ingenic_adc *adc,
> +				   uint32_t mask,
> +				   uint32_t val)
> +{
> +	uint32_t cfg;
> +
> +	clk_enable(adc->clk);
> +	mutex_lock(&adc->lock);
> +
> +	cfg = readl(adc->base + JZ_ADC_REG_CFG) & ~mask;
> +	cfg |= val;
> +	writel(cfg, adc->base + JZ_ADC_REG_CFG);
> +
> +	mutex_unlock(&adc->lock);
> +	clk_disable(adc->clk);
> +}
> +
> +static void ingenic_adc_enable(struct ingenic_adc *adc,
> +			       int engine,
> +			       bool enabled)
> +{
> +	u8 val;
> +
> +	mutex_lock(&adc->lock);
> +	val = readb(adc->base + JZ_ADC_REG_ENABLE);
> +
> +	if (enabled)
> +		val |= BIT(engine);
> +	else
> +		val &= ~BIT(engine);
> +
> +	writeb(val, adc->base + JZ_ADC_REG_ENABLE);
> +	mutex_unlock(&adc->lock);
> +}
> +
> +static int ingenic_adc_capture(struct ingenic_adc *adc,
> +			       int engine)
> +{
> +	u8 val;
> +	int ret;
> +
> +	ingenic_adc_enable(adc, engine, true);
> +	ret = readb_poll_timeout(adc->base + JZ_ADC_REG_ENABLE, val,
> +				 !(val & BIT(engine)), 250, 1000);
> +	if (ret)
> +		ingenic_adc_enable(adc, engine, false);
> +
> +	return ret;
> +}
> +
> +static int ingenic_adc_write_raw(struct iio_dev *iio_dev,
> +				 struct iio_chan_spec const *chan,
> +				 int val,
> +				 int val2,
> +				 long m)
> +{
> +	struct ingenic_adc *adc = iio_priv(iio_dev);
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->channel) {
> +		case INGENIC_ADC_BATTERY:
> +			if (val > JZ_ADC_BATTERY_LOW_VREF) {
> +				ingenic_adc_set_config(adc,
> +						       JZ_ADC_REG_CFG_BAT_MD,
> +						       0);
> +				adc->low_vref_mode = false;
> +			} else {
> +				ingenic_adc_set_config(adc,
> +						       JZ_ADC_REG_CFG_BAT_MD,
> +						       JZ_ADC_REG_CFG_BAT_MD);
> +				adc->low_vref_mode = true;
> +			}
> +			return 0;
> +		default:
> +			return -EINVAL;
> +		}
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const int jz4725b_adc_battery_raw_avail[] = {
> +	0, 1, (1 << JZ_ADC_BATTERY_LOW_VREF_BITS) - 1,
> +};
> +
> +static const int jz4725b_adc_battery_scale_avail[] = {
> +	JZ4725B_ADC_BATTERY_HIGH_VREF, JZ4725B_ADC_BATTERY_HIGH_VREF_BITS,
> +	JZ_ADC_BATTERY_LOW_VREF, JZ_ADC_BATTERY_LOW_VREF_BITS,
> +};
> +
> +static const int jz4740_adc_battery_raw_avail[] = {
> +	0, 1, (1 << JZ_ADC_BATTERY_LOW_VREF_BITS) - 1,
> +};
> +
> +static const int jz4740_adc_battery_scale_avail[] = {
> +	JZ4740_ADC_BATTERY_HIGH_VREF, JZ4740_ADC_BATTERY_HIGH_VREF_BITS,
> +	JZ_ADC_BATTERY_LOW_VREF, JZ_ADC_BATTERY_LOW_VREF_BITS,
> +};
> +
> +static const struct ingenic_adc_soc_data jz4725b_adc_soc_data = {
> +	.battery_high_vref = JZ4725B_ADC_BATTERY_HIGH_VREF,
> +	.battery_high_vref_bits = JZ4725B_ADC_BATTERY_HIGH_VREF_BITS,
> +	.battery_raw_avail = jz4725b_adc_battery_raw_avail,
> +	.battery_raw_avail_size = ARRAY_SIZE(jz4725b_adc_battery_raw_avail),
> +	.battery_scale_avail = jz4725b_adc_battery_scale_avail,
> +	.battery_scale_avail_size = ARRAY_SIZE(jz4725b_adc_battery_scale_avail),
> +};
> +
> +static const struct ingenic_adc_soc_data jz4740_adc_soc_data = {
> +	.battery_high_vref = JZ4740_ADC_BATTERY_HIGH_VREF,
> +	.battery_high_vref_bits = JZ4740_ADC_BATTERY_HIGH_VREF_BITS,
> +	.battery_raw_avail = jz4740_adc_battery_raw_avail,
> +	.battery_raw_avail_size = ARRAY_SIZE(jz4740_adc_battery_raw_avail),
> +	.battery_scale_avail = jz4740_adc_battery_scale_avail,
> +	.battery_scale_avail_size = ARRAY_SIZE(jz4740_adc_battery_scale_avail),
> +};
> +
> +static int ingenic_adc_read_avail(struct iio_dev *iio_dev,
> +				  struct iio_chan_spec const *chan,
> +				  const int **vals,
> +				  int *type,
> +				  int *length,
> +				  long m)
> +{
> +	struct ingenic_adc *adc = iio_priv(iio_dev);
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:
> +		*type = IIO_VAL_INT;
> +		*length = adc->soc_data->battery_raw_avail_size;
> +		*vals = adc->soc_data->battery_raw_avail;
> +		return IIO_AVAIL_RANGE;
> +	case IIO_CHAN_INFO_SCALE:
> +		*type = IIO_VAL_FRACTIONAL_LOG2;
> +		*length = adc->soc_data->battery_scale_avail_size;
> +		*vals = adc->soc_data->battery_scale_avail;
> +		return IIO_AVAIL_LIST;
> +	default:
> +		return -EINVAL;
> +	};
> +}
> +
> +static int ingenic_adc_read_raw(struct iio_dev *iio_dev,
> +				struct iio_chan_spec const *chan,
> +				int *val,
> +				int *val2,
> +				long m)
> +{
> +	struct ingenic_adc *adc = iio_priv(iio_dev);
> +	int ret;
> +
> +	switch (m) {
> +	case IIO_CHAN_INFO_RAW:
> +		clk_enable(adc->clk);
> +		ret = ingenic_adc_capture(adc, chan->channel);
> +		if (ret) {
> +			clk_disable(adc->clk);
> +			return ret;
> +		}
> +
> +		switch (chan->channel) {
> +		case INGENIC_ADC_AUX:
> +			*val = readw(adc->base + JZ_ADC_REG_ADSDAT);
> +			break;
> +		case INGENIC_ADC_BATTERY:
> +			*val = readw(adc->base + JZ_ADC_REG_ADBDAT);
> +			break;
> +		}
> +
> +		clk_disable(adc->clk);
> +
> +		return IIO_VAL_INT;
> +	case IIO_CHAN_INFO_SCALE:
> +		switch (chan->channel) {
> +		case INGENIC_ADC_AUX:
> +			*val = JZ_ADC_AUX_VREF;
> +			*val2 = JZ_ADC_AUX_VREF_BITS;
> +			break;
> +		case INGENIC_ADC_BATTERY:
> +			if (adc->low_vref_mode) {
> +				*val = JZ_ADC_BATTERY_LOW_VREF;
> +				*val2 = JZ_ADC_BATTERY_LOW_VREF_BITS;
> +			} else {
> +				*val = adc->soc_data->battery_high_vref;
> +				*val2 = adc->soc_data->battery_high_vref_bits;
> +			}
> +			break;
> +		}
> +
> +		return IIO_VAL_FRACTIONAL_LOG2;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static void ingenic_adc_clk_cleanup(void *data)
> +{
> +	clk_unprepare(data);
> +}
> +
> +static const struct iio_info ingenic_adc_info = {
> +	.write_raw = ingenic_adc_write_raw,
> +	.read_raw = ingenic_adc_read_raw,
> +	.read_avail = ingenic_adc_read_avail,
> +};
> +
> +static const struct iio_chan_spec ingenic_channels[] = {
> +	{
> +		.extend_name = "aux",
> +		.type = IIO_VOLTAGE,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE),
> +		.indexed = 1,
> +		.channel = INGENIC_ADC_AUX,
> +	},
> +	{
> +		.extend_name = "battery",
> +		.type = IIO_VOLTAGE,
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
> +				      BIT(IIO_CHAN_INFO_SCALE),
> +		.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW) |
> +						BIT(IIO_CHAN_INFO_SCALE),
> +		.indexed = 1,
> +		.channel = INGENIC_ADC_BATTERY,
> +	},
> +};
> +
> +static int ingenic_adc_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct iio_dev *iio_dev;
> +	struct ingenic_adc *adc;
> +	struct resource *mem_base;
> +	const struct ingenic_adc_soc_data *soc_data;
> +	int ret;
> +
> +	soc_data = device_get_match_data(dev);
> +	if (!soc_data)
> +		return -EINVAL;
> +
> +	iio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
> +	if (!iio_dev)
> +		return -ENOMEM;
> +
> +	adc = iio_priv(iio_dev);
> +	mutex_init(&adc->lock);
> +	adc->soc_data = soc_data;
> +
> +	mem_base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	adc->base = devm_ioremap_resource(dev, mem_base);
> +	if (IS_ERR(adc->base)) {
> +		dev_err(dev, "Unable to ioremap mmio resource\n");
> +		return PTR_ERR(adc->base);
> +	}
> +
> +	adc->clk = devm_clk_get(dev, "adc");
> +	if (IS_ERR(adc->clk)) {
> +		dev_err(dev, "Unable to get clock\n");
> +		return PTR_ERR(adc->clk);
> +	}
> +
> +	ret = clk_prepare_enable(adc->clk);
> +	if (ret) {
> +		dev_err(dev, "Failed to enable clock\n");
> +		return ret;
> +	}
> +
> +	/* Put hardware in a known passive state. */
> +	writeb(0x00, adc->base + JZ_ADC_REG_ENABLE);
> +	writeb(0xff, adc->base + JZ_ADC_REG_CTRL);
> +	clk_disable(adc->clk);
> +
> +	ret = devm_add_action_or_reset(dev, ingenic_adc_clk_cleanup, adc->clk);
> +	if (ret) {
> +		dev_err(dev, "Unable to add action\n");
> +		return ret;
> +	}
> +
> +	iio_dev->dev.parent = dev;
> +	iio_dev->name = "jz-adc";
> +	iio_dev->modes = INDIO_DIRECT_MODE;
> +	iio_dev->channels = ingenic_channels;
> +	iio_dev->num_channels = ARRAY_SIZE(ingenic_channels);
> +	iio_dev->info = &ingenic_adc_info;
> +
> +	ret = devm_iio_device_register(dev, iio_dev);
> +	if (ret)
Hmm. Most of the error paths in there provide more specific info
but there are a few with no error messages. I should clean that
up then drop all the drivers that print a fairly uninformative
message like this ;)

Oh well, not something to fix here. Either someone else will get
to it first or I'll clean it up some day.

> +		dev_err(dev, "Unable to register IIO device\n");
> +
> +	return ret;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id ingenic_adc_of_match[] = {
> +	{ .compatible = "ingenic,jz4725b-adc", .data = &jz4725b_adc_soc_data, },
> +	{ .compatible = "ingenic,jz4740-adc", .data = &jz4740_adc_soc_data, },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, ingenic_adc_of_match);
> +#endif
> +
> +static struct platform_driver ingenic_adc_driver = {
> +	.driver = {
> +		.name = "ingenic-adc",
> +		.of_match_table = of_match_ptr(ingenic_adc_of_match),
> +	},
> +	.probe = ingenic_adc_probe,
> +};
> +module_platform_driver(ingenic_adc_driver);
Artur Rojek Feb. 9, 2019, 4:13 p.m. | #3
On 2019-02-09 16:39, Jonathan Cameron wrote:
> On Mon,  4 Feb 2019 01:15:14 +0100
> Artur Rojek <contact@artur-rojek.eu> wrote:
> 
>> Add an IIO driver for the ADC hardware present on Ingenic JZ47xx SoCs.
>> 
>> Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
> Applied to the togreg branch of iio.git and pushed out as testing for
> the autobuilders to play with it.
> 
Thanks for the review, Jonathan.

Artur

> One note inline, but more for something general we should tidy up
> than a change in this driver!
> 
> Thanks,
> 
> Jonathan
> 
>> ---
>> 
>>  Changes:
>> 
>>  v2: - prefix all platform defines with JZ_ADC_*,
>>      - replace spinlock with a mutex,
>>      - change devm_add_action to devm_add_action_or_reset,
>>      - add a function wrapper for clk_unprepare,
>>      - change iio_dev->name from "adc" to "jz-adc",
>>      - simplify error handling code for devm_iio_device_register
>> 
>>  drivers/iio/adc/Kconfig       |   9 +
>>  drivers/iio/adc/Makefile      |   1 +
>>  drivers/iio/adc/ingenic-adc.c | 363 
>> ++++++++++++++++++++++++++++++++++
>>  3 files changed, 373 insertions(+)
>>  create mode 100644 drivers/iio/adc/ingenic-adc.c
>> 
>> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
>> index 7a3ca4ec0cb7..f9f349a22b04 100644
>> --- a/drivers/iio/adc/Kconfig
>> +++ b/drivers/iio/adc/Kconfig
>> @@ -367,6 +367,15 @@ config INA2XX_ADC
>>  	  Say yes here to build support for TI INA2xx family of Power 
>> Monitors.
>>  	  This driver is mutually exclusive with the HWMON version.
>> 
>> +config INGENIC_ADC
>> +	tristate "Ingenic JZ47xx SoCs ADC driver"
>> +	depends on MIPS || COMPILE_TEST
>> +	help
>> +	  Say yes here to build support for the Ingenic JZ47xx SoCs ADC 
>> unit.
>> +
>> +	  This driver can also be built as a module. If so, the module will 
>> be
>> +	  called ingenic_adc.
>> +
>>  config IMX7D_ADC
>>  	tristate "Freescale IMX7D ADC driver"
>>  	depends on ARCH_MXC || COMPILE_TEST
>> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
>> index 07df37f621bd..0a7acab33b91 100644
>> --- a/drivers/iio/adc/Makefile
>> +++ b/drivers/iio/adc/Makefile
>> @@ -36,6 +36,7 @@ obj-$(CONFIG_HI8435) += hi8435.o
>>  obj-$(CONFIG_HX711) += hx711.o
>>  obj-$(CONFIG_IMX7D_ADC) += imx7d_adc.o
>>  obj-$(CONFIG_INA2XX_ADC) += ina2xx-adc.o
>> +obj-$(CONFIG_INGENIC_ADC) += ingenic-adc.o
>>  obj-$(CONFIG_LP8788_ADC) += lp8788_adc.o
>>  obj-$(CONFIG_LPC18XX_ADC) += lpc18xx_adc.o
>>  obj-$(CONFIG_LPC32XX_ADC) += lpc32xx_adc.o
>> diff --git a/drivers/iio/adc/ingenic-adc.c 
>> b/drivers/iio/adc/ingenic-adc.c
>> new file mode 100644
>> index 000000000000..1f436df1fd45
>> --- /dev/null
>> +++ b/drivers/iio/adc/ingenic-adc.c
>> @@ -0,0 +1,363 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * ADC driver for the Ingenic JZ47xx SoCs
>> + * Copyright (c) 2019 Artur Rojek <contact@artur-rojek.eu>
>> + *
>> + * based on drivers/mfd/jz4740-adc.c
>> + */
>> +
>> +#include <dt-bindings/iio/adc/ingenic,adc.h>
>> +#include <linux/clk.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/io.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define JZ_ADC_REG_ENABLE		0x00
>> +#define JZ_ADC_REG_CFG			0x04
>> +#define JZ_ADC_REG_CTRL			0x08
>> +#define JZ_ADC_REG_STATUS		0x0c
>> +#define JZ_ADC_REG_ADTCH		0x18
>> +#define JZ_ADC_REG_ADBDAT		0x1c
>> +#define JZ_ADC_REG_ADSDAT		0x20
>> +
>> +#define JZ_ADC_REG_CFG_BAT_MD		BIT(4)
>> +
>> +#define JZ_ADC_AUX_VREF				3300
>> +#define JZ_ADC_AUX_VREF_BITS			12
>> +#define JZ_ADC_BATTERY_LOW_VREF			2500
>> +#define JZ_ADC_BATTERY_LOW_VREF_BITS		12
>> +#define JZ4725B_ADC_BATTERY_HIGH_VREF		7500
>> +#define JZ4725B_ADC_BATTERY_HIGH_VREF_BITS	10
>> +#define JZ4740_ADC_BATTERY_HIGH_VREF		(7500 * 0.986)
>> +#define JZ4740_ADC_BATTERY_HIGH_VREF_BITS	12
>> +
>> +struct ingenic_adc_soc_data {
>> +	unsigned int battery_high_vref;
>> +	unsigned int battery_high_vref_bits;
>> +	const int *battery_raw_avail;
>> +	size_t battery_raw_avail_size;
>> +	const int *battery_scale_avail;
>> +	size_t battery_scale_avail_size;
>> +};
>> +
>> +struct ingenic_adc {
>> +	void __iomem *base;
>> +	struct clk *clk;
>> +	struct mutex lock;
>> +	const struct ingenic_adc_soc_data *soc_data;
>> +	bool low_vref_mode;
>> +};
>> +
>> +static void ingenic_adc_set_config(struct ingenic_adc *adc,
>> +				   uint32_t mask,
>> +				   uint32_t val)
>> +{
>> +	uint32_t cfg;
>> +
>> +	clk_enable(adc->clk);
>> +	mutex_lock(&adc->lock);
>> +
>> +	cfg = readl(adc->base + JZ_ADC_REG_CFG) & ~mask;
>> +	cfg |= val;
>> +	writel(cfg, adc->base + JZ_ADC_REG_CFG);
>> +
>> +	mutex_unlock(&adc->lock);
>> +	clk_disable(adc->clk);
>> +}
>> +
>> +static void ingenic_adc_enable(struct ingenic_adc *adc,
>> +			       int engine,
>> +			       bool enabled)
>> +{
>> +	u8 val;
>> +
>> +	mutex_lock(&adc->lock);
>> +	val = readb(adc->base + JZ_ADC_REG_ENABLE);
>> +
>> +	if (enabled)
>> +		val |= BIT(engine);
>> +	else
>> +		val &= ~BIT(engine);
>> +
>> +	writeb(val, adc->base + JZ_ADC_REG_ENABLE);
>> +	mutex_unlock(&adc->lock);
>> +}
>> +
>> +static int ingenic_adc_capture(struct ingenic_adc *adc,
>> +			       int engine)
>> +{
>> +	u8 val;
>> +	int ret;
>> +
>> +	ingenic_adc_enable(adc, engine, true);
>> +	ret = readb_poll_timeout(adc->base + JZ_ADC_REG_ENABLE, val,
>> +				 !(val & BIT(engine)), 250, 1000);
>> +	if (ret)
>> +		ingenic_adc_enable(adc, engine, false);
>> +
>> +	return ret;
>> +}
>> +
>> +static int ingenic_adc_write_raw(struct iio_dev *iio_dev,
>> +				 struct iio_chan_spec const *chan,
>> +				 int val,
>> +				 int val2,
>> +				 long m)
>> +{
>> +	struct ingenic_adc *adc = iio_priv(iio_dev);
>> +
>> +	switch (m) {
>> +	case IIO_CHAN_INFO_SCALE:
>> +		switch (chan->channel) {
>> +		case INGENIC_ADC_BATTERY:
>> +			if (val > JZ_ADC_BATTERY_LOW_VREF) {
>> +				ingenic_adc_set_config(adc,
>> +						       JZ_ADC_REG_CFG_BAT_MD,
>> +						       0);
>> +				adc->low_vref_mode = false;
>> +			} else {
>> +				ingenic_adc_set_config(adc,
>> +						       JZ_ADC_REG_CFG_BAT_MD,
>> +						       JZ_ADC_REG_CFG_BAT_MD);
>> +				adc->low_vref_mode = true;
>> +			}
>> +			return 0;
>> +		default:
>> +			return -EINVAL;
>> +		}
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +}
>> +
>> +static const int jz4725b_adc_battery_raw_avail[] = {
>> +	0, 1, (1 << JZ_ADC_BATTERY_LOW_VREF_BITS) - 1,
>> +};
>> +
>> +static const int jz4725b_adc_battery_scale_avail[] = {
>> +	JZ4725B_ADC_BATTERY_HIGH_VREF, JZ4725B_ADC_BATTERY_HIGH_VREF_BITS,
>> +	JZ_ADC_BATTERY_LOW_VREF, JZ_ADC_BATTERY_LOW_VREF_BITS,
>> +};
>> +
>> +static const int jz4740_adc_battery_raw_avail[] = {
>> +	0, 1, (1 << JZ_ADC_BATTERY_LOW_VREF_BITS) - 1,
>> +};
>> +
>> +static const int jz4740_adc_battery_scale_avail[] = {
>> +	JZ4740_ADC_BATTERY_HIGH_VREF, JZ4740_ADC_BATTERY_HIGH_VREF_BITS,
>> +	JZ_ADC_BATTERY_LOW_VREF, JZ_ADC_BATTERY_LOW_VREF_BITS,
>> +};
>> +
>> +static const struct ingenic_adc_soc_data jz4725b_adc_soc_data = {
>> +	.battery_high_vref = JZ4725B_ADC_BATTERY_HIGH_VREF,
>> +	.battery_high_vref_bits = JZ4725B_ADC_BATTERY_HIGH_VREF_BITS,
>> +	.battery_raw_avail = jz4725b_adc_battery_raw_avail,
>> +	.battery_raw_avail_size = ARRAY_SIZE(jz4725b_adc_battery_raw_avail),
>> +	.battery_scale_avail = jz4725b_adc_battery_scale_avail,
>> +	.battery_scale_avail_size = 
>> ARRAY_SIZE(jz4725b_adc_battery_scale_avail),
>> +};
>> +
>> +static const struct ingenic_adc_soc_data jz4740_adc_soc_data = {
>> +	.battery_high_vref = JZ4740_ADC_BATTERY_HIGH_VREF,
>> +	.battery_high_vref_bits = JZ4740_ADC_BATTERY_HIGH_VREF_BITS,
>> +	.battery_raw_avail = jz4740_adc_battery_raw_avail,
>> +	.battery_raw_avail_size = ARRAY_SIZE(jz4740_adc_battery_raw_avail),
>> +	.battery_scale_avail = jz4740_adc_battery_scale_avail,
>> +	.battery_scale_avail_size = 
>> ARRAY_SIZE(jz4740_adc_battery_scale_avail),
>> +};
>> +
>> +static int ingenic_adc_read_avail(struct iio_dev *iio_dev,
>> +				  struct iio_chan_spec const *chan,
>> +				  const int **vals,
>> +				  int *type,
>> +				  int *length,
>> +				  long m)
>> +{
>> +	struct ingenic_adc *adc = iio_priv(iio_dev);
>> +
>> +	switch (m) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		*type = IIO_VAL_INT;
>> +		*length = adc->soc_data->battery_raw_avail_size;
>> +		*vals = adc->soc_data->battery_raw_avail;
>> +		return IIO_AVAIL_RANGE;
>> +	case IIO_CHAN_INFO_SCALE:
>> +		*type = IIO_VAL_FRACTIONAL_LOG2;
>> +		*length = adc->soc_data->battery_scale_avail_size;
>> +		*vals = adc->soc_data->battery_scale_avail;
>> +		return IIO_AVAIL_LIST;
>> +	default:
>> +		return -EINVAL;
>> +	};
>> +}
>> +
>> +static int ingenic_adc_read_raw(struct iio_dev *iio_dev,
>> +				struct iio_chan_spec const *chan,
>> +				int *val,
>> +				int *val2,
>> +				long m)
>> +{
>> +	struct ingenic_adc *adc = iio_priv(iio_dev);
>> +	int ret;
>> +
>> +	switch (m) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		clk_enable(adc->clk);
>> +		ret = ingenic_adc_capture(adc, chan->channel);
>> +		if (ret) {
>> +			clk_disable(adc->clk);
>> +			return ret;
>> +		}
>> +
>> +		switch (chan->channel) {
>> +		case INGENIC_ADC_AUX:
>> +			*val = readw(adc->base + JZ_ADC_REG_ADSDAT);
>> +			break;
>> +		case INGENIC_ADC_BATTERY:
>> +			*val = readw(adc->base + JZ_ADC_REG_ADBDAT);
>> +			break;
>> +		}
>> +
>> +		clk_disable(adc->clk);
>> +
>> +		return IIO_VAL_INT;
>> +	case IIO_CHAN_INFO_SCALE:
>> +		switch (chan->channel) {
>> +		case INGENIC_ADC_AUX:
>> +			*val = JZ_ADC_AUX_VREF;
>> +			*val2 = JZ_ADC_AUX_VREF_BITS;
>> +			break;
>> +		case INGENIC_ADC_BATTERY:
>> +			if (adc->low_vref_mode) {
>> +				*val = JZ_ADC_BATTERY_LOW_VREF;
>> +				*val2 = JZ_ADC_BATTERY_LOW_VREF_BITS;
>> +			} else {
>> +				*val = adc->soc_data->battery_high_vref;
>> +				*val2 = adc->soc_data->battery_high_vref_bits;
>> +			}
>> +			break;
>> +		}
>> +
>> +		return IIO_VAL_FRACTIONAL_LOG2;
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +}
>> +
>> +static void ingenic_adc_clk_cleanup(void *data)
>> +{
>> +	clk_unprepare(data);
>> +}
>> +
>> +static const struct iio_info ingenic_adc_info = {
>> +	.write_raw = ingenic_adc_write_raw,
>> +	.read_raw = ingenic_adc_read_raw,
>> +	.read_avail = ingenic_adc_read_avail,
>> +};
>> +
>> +static const struct iio_chan_spec ingenic_channels[] = {
>> +	{
>> +		.extend_name = "aux",
>> +		.type = IIO_VOLTAGE,
>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>> +				      BIT(IIO_CHAN_INFO_SCALE),
>> +		.indexed = 1,
>> +		.channel = INGENIC_ADC_AUX,
>> +	},
>> +	{
>> +		.extend_name = "battery",
>> +		.type = IIO_VOLTAGE,
>> +		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>> +				      BIT(IIO_CHAN_INFO_SCALE),
>> +		.info_mask_separate_available = BIT(IIO_CHAN_INFO_RAW) |
>> +						BIT(IIO_CHAN_INFO_SCALE),
>> +		.indexed = 1,
>> +		.channel = INGENIC_ADC_BATTERY,
>> +	},
>> +};
>> +
>> +static int ingenic_adc_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct iio_dev *iio_dev;
>> +	struct ingenic_adc *adc;
>> +	struct resource *mem_base;
>> +	const struct ingenic_adc_soc_data *soc_data;
>> +	int ret;
>> +
>> +	soc_data = device_get_match_data(dev);
>> +	if (!soc_data)
>> +		return -EINVAL;
>> +
>> +	iio_dev = devm_iio_device_alloc(dev, sizeof(*adc));
>> +	if (!iio_dev)
>> +		return -ENOMEM;
>> +
>> +	adc = iio_priv(iio_dev);
>> +	mutex_init(&adc->lock);
>> +	adc->soc_data = soc_data;
>> +
>> +	mem_base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	adc->base = devm_ioremap_resource(dev, mem_base);
>> +	if (IS_ERR(adc->base)) {
>> +		dev_err(dev, "Unable to ioremap mmio resource\n");
>> +		return PTR_ERR(adc->base);
>> +	}
>> +
>> +	adc->clk = devm_clk_get(dev, "adc");
>> +	if (IS_ERR(adc->clk)) {
>> +		dev_err(dev, "Unable to get clock\n");
>> +		return PTR_ERR(adc->clk);
>> +	}
>> +
>> +	ret = clk_prepare_enable(adc->clk);
>> +	if (ret) {
>> +		dev_err(dev, "Failed to enable clock\n");
>> +		return ret;
>> +	}
>> +
>> +	/* Put hardware in a known passive state. */
>> +	writeb(0x00, adc->base + JZ_ADC_REG_ENABLE);
>> +	writeb(0xff, adc->base + JZ_ADC_REG_CTRL);
>> +	clk_disable(adc->clk);
>> +
>> +	ret = devm_add_action_or_reset(dev, ingenic_adc_clk_cleanup, 
>> adc->clk);
>> +	if (ret) {
>> +		dev_err(dev, "Unable to add action\n");
>> +		return ret;
>> +	}
>> +
>> +	iio_dev->dev.parent = dev;
>> +	iio_dev->name = "jz-adc";
>> +	iio_dev->modes = INDIO_DIRECT_MODE;
>> +	iio_dev->channels = ingenic_channels;
>> +	iio_dev->num_channels = ARRAY_SIZE(ingenic_channels);
>> +	iio_dev->info = &ingenic_adc_info;
>> +
>> +	ret = devm_iio_device_register(dev, iio_dev);
>> +	if (ret)
> Hmm. Most of the error paths in there provide more specific info
> but there are a few with no error messages. I should clean that
> up then drop all the drivers that print a fairly uninformative
> message like this ;)
> 
> Oh well, not something to fix here. Either someone else will get
> to it first or I'll clean it up some day.
> 
>> +		dev_err(dev, "Unable to register IIO device\n");
>> +
>> +	return ret;
>> +}
>> +
>> +#ifdef CONFIG_OF
>> +static const struct of_device_id ingenic_adc_of_match[] = {
>> +	{ .compatible = "ingenic,jz4725b-adc", .data = 
>> &jz4725b_adc_soc_data, },
>> +	{ .compatible = "ingenic,jz4740-adc", .data = &jz4740_adc_soc_data, 
>> },
>> +	{ },
>> +};
>> +MODULE_DEVICE_TABLE(of, ingenic_adc_of_match);
>> +#endif
>> +
>> +static struct platform_driver ingenic_adc_driver = {
>> +	.driver = {
>> +		.name = "ingenic-adc",
>> +		.of_match_table = of_match_ptr(ingenic_adc_of_match),
>> +	},
>> +	.probe = ingenic_adc_probe,
>> +};
>> +module_platform_driver(ingenic_adc_driver);

Patch

diff --git a/Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt b/Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt
new file mode 100644
index 000000000000..f01159f20d87
--- /dev/null
+++ b/Documentation/devicetree/bindings/iio/adc/ingenic,adc.txt
@@ -0,0 +1,48 @@ 
+* Ingenic JZ47xx ADC controller IIO bindings
+
+Required properties:
+
+- compatible: Should be one of:
+  * ingenic,jz4725b-adc
+  * ingenic,jz4740-adc
+- reg: ADC controller registers location and length.
+- clocks: phandle to the SoC's ADC clock.
+- clock-names: Must be set to "adc".
+- #io-channel-cells: Must be set to <1> to indicate channels are selected
+  by index.
+
+ADC clients must use the format described in iio-bindings.txt, giving
+a phandle and IIO specifier pair ("io-channels") to the ADC controller.
+
+Example:
+
+#include <dt-bindings/iio/adc/ingenic,adc.h>
+
+adc: adc@10070000 {
+	compatible = "ingenic,jz4740-adc";
+	#io-channel-cells = <1>;
+
+	reg = <0x10070000 0x30>;
+
+	clocks = <&cgu JZ4740_CLK_ADC>;
+	clock-names = "adc";
+
+	interrupt-parent = <&intc>;
+	interrupts = <18>;
+};
+
+adc-keys {
+	...
+	compatible = "adc-keys";
+	io-channels = <&adc INGENIC_ADC_AUX>;
+	io-channel-names = "buttons";
+	...
+};
+
+battery {
+	...
+	compatible = "ingenic,jz4740-battery";
+	io-channels = <&adc INGENIC_ADC_BATTERY>;
+	io-channel-names = "battery";
+	...
+};