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

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

[Artur Rojek]

Add documentation for the ADC controller on JZ47xx SoCs,
used by the ingenic-adc driver.

Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
---
 .../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..884f459bb9b9
--- /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";
+	...
+};
-- 
2.20.1

[PATCH 2/3] dt-bindings: iio/adc: Add bindings for Ingenic JZ47xx SoCs ADC.

[Artur Rojek]

Add device tree bindings for the ADC controller on JZ47xx SoCs,
used by the ingenic-adc driver.

Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
---
 include/dt-bindings/iio/adc/ingenic,adc.h | 10 ++++++++++
 1 file changed, 10 insertions(+)
 create mode 100644 include/dt-bindings/iio/adc/ingenic,adc.h

diff --git a/include/dt-bindings/iio/adc/ingenic,adc.h b/include/dt-bindings/iio/adc/ingenic,adc.h
new file mode 100644
index 000000000000..82706b2706ac
--- /dev/null
+++ b/include/dt-bindings/iio/adc/ingenic,adc.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _DT_BINDINGS_IIO_ADC_INGENIC_ADC_H
+#define _DT_BINDINGS_IIO_ADC_INGENIC_ADC_H
+
+/* ADC channel idx. */
+#define INGENIC_ADC_AUX		0
+#define INGENIC_ADC_BATTERY	1
+
+#endif
-- 
2.20.1

[PATCH 3/3] IIO: add Ingenic JZ47xx ADC driver.

[Artur Rojek]

Add an IIO driver for the ADC hardware present on Ingenic JZ47xx SoCs.

Signed-off-by: Artur Rojek <contact@artur-rojek.eu>
---
 drivers/iio/adc/Kconfig       |   9 +
 drivers/iio/adc/Makefile      |   1 +
 drivers/iio/adc/ingenic-adc.c | 357 ++++++++++++++++++++++++++++++++++
 3 files changed, 367 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..4235d46a3d37
--- /dev/null
+++ b/drivers/iio/adc/ingenic-adc.c
@@ -0,0 +1,357 @@
+// 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/platform_device.h>
+#include <linux/spinlock.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 REG_CFG_BAT_MD			BIT(4)
+
+#define AUX_VREF			3300
+#define AUX_VREF_BITS			12
+#define BATTERY_LOW_VREF		2500
+#define BATTERY_LOW_VREF_BITS		12
+#define JZ4725B_BATTERY_HIGH_VREF	7500
+#define JZ4725B_BATTERY_HIGH_VREF_BITS	10
+#define JZ4740_BATTERY_HIGH_VREF	(7500 * 0.986)
+#define JZ4740_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;
+	spinlock_t 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)
+{
+	unsigned long flags;
+	uint32_t cfg;
+
+	clk_enable(adc->clk);
+	spin_lock_irqsave(&adc->lock, flags);
+
+	cfg = readl(adc->base + JZ_ADC_REG_CFG) & ~mask;
+	cfg |= val;
+	writel(cfg, adc->base + JZ_ADC_REG_CFG);
+
+	spin_unlock_irqrestore(&adc->lock, flags);
+	clk_disable(adc->clk);
+}
+
+static void ingenic_adc_enable(struct ingenic_adc *adc,
+			       int engine,
+			       bool enabled)
+{
+	unsigned long flags;
+	u8 val;
+
+	spin_lock_irqsave(&adc->lock, flags);
+	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);
+	spin_unlock_irqrestore(&adc->lock, flags);
+}
+
+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 > BATTERY_LOW_VREF) {
+				ingenic_adc_set_config(adc,
+						       REG_CFG_BAT_MD,
+						       0);
+				adc->low_vref_mode = false;
+			} else {
+				ingenic_adc_set_config(adc,
+						       REG_CFG_BAT_MD,
+						       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 << BATTERY_LOW_VREF_BITS) - 1,
+};
+
+static const int jz4725b_adc_battery_scale_avail[] = {
+	JZ4725B_BATTERY_HIGH_VREF, JZ4725B_BATTERY_HIGH_VREF_BITS,
+	BATTERY_LOW_VREF, BATTERY_LOW_VREF_BITS,
+};
+
+static const int jz4740_adc_battery_raw_avail[] = {
+	0, 1, (1 << BATTERY_LOW_VREF_BITS) - 1,
+};
+
+static const int jz4740_adc_battery_scale_avail[] = {
+	JZ4740_BATTERY_HIGH_VREF, JZ4740_BATTERY_HIGH_VREF_BITS,
+	BATTERY_LOW_VREF, BATTERY_LOW_VREF_BITS,
+};
+
+static const struct ingenic_adc_soc_data jz4725b_adc_soc_data = {
+	.battery_high_vref = JZ4725B_BATTERY_HIGH_VREF,
+	.battery_high_vref_bits = JZ4725B_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_BATTERY_HIGH_VREF,
+	.battery_high_vref_bits = JZ4740_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 = AUX_VREF;
+			*val2 = AUX_VREF_BITS;
+			break;
+		case INGENIC_ADC_BATTERY:
+			if (adc->low_vref_mode) {
+				*val = BATTERY_LOW_VREF;
+				*val2 = 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 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 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(&pdev->dev);
+	if (!soc_data)
+		return -EINVAL;
+
+	iio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
+	if (!iio_dev)
+		return -ENOMEM;
+
+	adc = iio_priv(iio_dev);
+	spin_lock_init(&adc->lock);
+	adc->soc_data = soc_data;
+
+	mem_base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	adc->base = devm_ioremap_resource(&pdev->dev, mem_base);
+	if (IS_ERR(adc->base)) {
+		dev_err(&pdev->dev, "Unable to ioremap mmio resource\n");
+		return PTR_ERR(adc->base);
+	}
+
+	adc->clk = devm_clk_get(&pdev->dev, "adc");
+	if (IS_ERR(adc->clk)) {
+		dev_err(&pdev->dev, "Unable to get clock\n");
+		return PTR_ERR(adc->clk);
+	}
+
+	ret = clk_prepare_enable(adc->clk);
+	if (ret) {
+		dev_err(&pdev->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);
+
+	devm_add_action(&pdev->dev, (void (*)(void *))clk_unprepare, adc->clk);
+
+	iio_dev->dev.parent = &pdev->dev;
+	iio_dev->name = "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(&pdev->dev, iio_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "Unable to register IIO device\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+#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);
-- 
2.20.1

Re: [PATCH 3/3] IIO: add Ingenic JZ47xx ADC driver.

[Jonathan Cameron]

On Mon, 28 Jan 2019 14:02:41 +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>

Looks pretty good to me.  A few minor things inline.

Thanks,

Jonathan
> ---
>  drivers/iio/adc/Kconfig       |   9 +
>  drivers/iio/adc/Makefile      |   1 +
>  drivers/iio/adc/ingenic-adc.c | 357 ++++++++++++++++++++++++++++++++++
>  3 files changed, 367 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..4235d46a3d37
> --- /dev/null
> +++ b/drivers/iio/adc/ingenic-adc.c
> @@ -0,0 +1,357 @@
> +// 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/platform_device.h>
> +#include <linux/spinlock.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 REG_CFG_BAT_MD			BIT(4)

Please prefix all these as well to avoid a potential name clash with a header
in the future.  Better to avoid it now!

> +
> +#define AUX_VREF			3300
> +#define AUX_VREF_BITS			12
> +#define BATTERY_LOW_VREF		2500
> +#define BATTERY_LOW_VREF_BITS		12
> +#define JZ4725B_BATTERY_HIGH_VREF	7500
> +#define JZ4725B_BATTERY_HIGH_VREF_BITS	10
> +#define JZ4740_BATTERY_HIGH_VREF	(7500 * 0.986)
> +#define JZ4740_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;

> +	spinlock_t lock;
This isn't taken anywhere that can't sleep, so mutex preferred to play
nice with realtime kernels etc.

> +	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)
> +{
> +	unsigned long flags;
> +	uint32_t cfg;
> +
> +	clk_enable(adc->clk);
> +	spin_lock_irqsave(&adc->lock, flags);
> +
> +	cfg = readl(adc->base + JZ_ADC_REG_CFG) & ~mask;
> +	cfg |= val;
> +	writel(cfg, adc->base + JZ_ADC_REG_CFG);
> +
> +	spin_unlock_irqrestore(&adc->lock, flags);
> +	clk_disable(adc->clk);
> +}
> +
> +static void ingenic_adc_enable(struct ingenic_adc *adc,
> +			       int engine,
> +			       bool enabled)
> +{
> +	unsigned long flags;
> +	u8 val;
> +
> +	spin_lock_irqsave(&adc->lock, flags);
> +	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);
> +	spin_unlock_irqrestore(&adc->lock, flags);
> +}
> +
> +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 > BATTERY_LOW_VREF) {
> +				ingenic_adc_set_config(adc,
> +						       REG_CFG_BAT_MD,
> +						       0);
> +				adc->low_vref_mode = false;
> +			} else {
> +				ingenic_adc_set_config(adc,
> +						       REG_CFG_BAT_MD,
> +						       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 << BATTERY_LOW_VREF_BITS) - 1,
> +};
> +
> +static const int jz4725b_adc_battery_scale_avail[] = {
> +	JZ4725B_BATTERY_HIGH_VREF, JZ4725B_BATTERY_HIGH_VREF_BITS,
> +	BATTERY_LOW_VREF, BATTERY_LOW_VREF_BITS,
> +};
> +
> +static const int jz4740_adc_battery_raw_avail[] = {
> +	0, 1, (1 << BATTERY_LOW_VREF_BITS) - 1,
> +};
> +
> +static const int jz4740_adc_battery_scale_avail[] = {
> +	JZ4740_BATTERY_HIGH_VREF, JZ4740_BATTERY_HIGH_VREF_BITS,
> +	BATTERY_LOW_VREF, BATTERY_LOW_VREF_BITS,
> +};
> +
> +static const struct ingenic_adc_soc_data jz4725b_adc_soc_data = {
> +	.battery_high_vref = JZ4725B_BATTERY_HIGH_VREF,
> +	.battery_high_vref_bits = JZ4725B_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_BATTERY_HIGH_VREF,
> +	.battery_high_vref_bits = JZ4740_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 = AUX_VREF;
> +			*val2 = AUX_VREF_BITS;
> +			break;
> +		case INGENIC_ADC_BATTERY:
> +			if (adc->low_vref_mode) {
> +				*val = BATTERY_LOW_VREF;
> +				*val2 = 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 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 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(&pdev->dev);
> +	if (!soc_data)
> +		return -EINVAL;
> +
> +	iio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc));
> +	if (!iio_dev)
> +		return -ENOMEM;
> +
> +	adc = iio_priv(iio_dev);
> +	spin_lock_init(&adc->lock);
> +	adc->soc_data = soc_data;
> +
> +	mem_base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	adc->base = devm_ioremap_resource(&pdev->dev, mem_base);
> +	if (IS_ERR(adc->base)) {
> +		dev_err(&pdev->dev, "Unable to ioremap mmio resource\n");
> +		return PTR_ERR(adc->base);
> +	}
> +
> +	adc->clk = devm_clk_get(&pdev->dev, "adc");
> +	if (IS_ERR(adc->clk)) {
> +		dev_err(&pdev->dev, "Unable to get clock\n");
> +		return PTR_ERR(adc->clk);
> +	}
> +
> +	ret = clk_prepare_enable(adc->clk);
> +	if (ret) {
> +		dev_err(&pdev->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);
> +
> +	devm_add_action(&pdev->dev, (void (*)(void *))clk_unprepare, adc->clk);
Don't cast the function, just have a little wrapper with the right signature.

This can fail.  Call devm_add_action_or_reset instead and handle the return value.

> +
> +	iio_dev->dev.parent = &pdev->dev;
> +	iio_dev->name = "adc";

The name needs to identify this part as opposed to any other ADCs plugged into the
board.  I would suggest using jz4725b of jz4740 as appropriate.

> +	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(&pdev->dev, iio_dev);
> +	if (ret) {
> +		dev_err(&pdev->dev, "Unable to register IIO device\n");
> +		return ret;
> +	}
> +
> +	return 0;

Drop the return ret out of the brackets above and this isn't needed.

> +}
> +
> +#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);