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

[Jonathan Cameron <jonathan.cameron@huawei.com>]

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);