Re: [PATCH v2 2/4] iio: adc: add support for Allwinner SoCs ADC

From: Maxime Ripard
Date: Mon Jul 18 2016 - 08:58:20 EST


On Fri, Jul 15, 2016 at 11:59:12AM +0200, Quentin Schulz wrote:
> The Allwinner SoCs all have an ADC that can also act as a touchscreen
> controller and a thermal sensor. This patch adds the ADC driver which is
> based on the MFD for the same SoCs ADC.
>
> This also registers the thermal adc channel in the iio map array so
> iio_hwmon could use it without modifying the Device Tree.
>
> This driver probes on three different platform_device_id to take into
> account slight differences between Allwinner SoCs ADCs.
>
> Signed-off-by: Quentin Schulz <quentin.schulz@xxxxxxxxxxxxxxxxxx>
> ---
>
> v2:
> - add SUNXI_GPADC_ prefixes for defines,
> - correct typo in Kconfig,
> - reorder alphabetically includes, makefile,
> - add license header,
> - fix architecture variations not being handled in interrupt handlers or
> read raw functions,
> - fix unability to return negative values from thermal sensor,
> - add gotos to reduce code repetition,
> - fix irq variable being unsigned int instead of int,
> - remove useless dev_err and dev_info,
> - deactivate all interrupts if probe fails,
> - fix iio_device_register on NULL variable,
> - deactivate ADC in the IP when probe fails or when removing driver,
>
> drivers/iio/adc/Kconfig | 12 ++
> drivers/iio/adc/Makefile | 1 +
> drivers/iio/adc/sunxi-gpadc-iio.c | 417 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 430 insertions(+)
> create mode 100644 drivers/iio/adc/sunxi-gpadc-iio.c
>
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 25378c5..184856f 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -338,6 +338,18 @@ config NAU7802
> To compile this driver as a module, choose M here: the
> module will be called nau7802.
>
> +config SUNXI_ADC

We try to avoid the SUNXI prefix usually, otherwise this driver will
have a generic name (or at least is implicitly saying that it supports
all the sunxi SoCs), while it supports only a subset of those SoCs.

> + tristate "ADC driver for sunxi platforms"

And you should also mention which ADC is supported, since we usually
have several of them.

Something like "Support for the Allwinner SoCs GPADC"

> + depends on IIO
> + depends on MFD_SUNXI_ADC

The order of your patches is quite weird. You depend on an option that
is not present yet?

> + help
> + Say yes here to build support for Allwinner (A10, A13 and A31) SoCs
> + ADC. This ADC provides 4 channels which can be used as an ADC or as a
> + touchscreen input and one channel for thermal sensor.
> +
> + To compile this driver as a module, choose M here: the module will be

Your indentation is weird here, and the wrapping is likely to be wrong
too.

> + called sunxi-gpadc-iio.
> +
> config PALMAS_GPADC
> tristate "TI Palmas General Purpose ADC"
> depends on MFD_PALMAS
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 38638d4..3e60a1d 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -37,6 +37,7 @@ obj-$(CONFIG_PALMAS_GPADC) += palmas_gpadc.o
> obj-$(CONFIG_QCOM_SPMI_IADC) += qcom-spmi-iadc.o
> obj-$(CONFIG_QCOM_SPMI_VADC) += qcom-spmi-vadc.o
> obj-$(CONFIG_ROCKCHIP_SARADC) += rockchip_saradc.o
> +obj-$(CONFIG_SUNXI_ADC) += sunxi-gpadc-iio.o
> obj-$(CONFIG_TI_ADC081C) += ti-adc081c.o
> obj-$(CONFIG_TI_ADC0832) += ti-adc0832.o
> obj-$(CONFIG_TI_ADC128S052) += ti-adc128s052.o
> diff --git a/drivers/iio/adc/sunxi-gpadc-iio.c b/drivers/iio/adc/sunxi-gpadc-iio.c
> new file mode 100644
> index 0000000..87cc913
> --- /dev/null
> +++ b/drivers/iio/adc/sunxi-gpadc-iio.c
> @@ -0,0 +1,417 @@
> +/* ADC driver for sunxi platforms
> + *
> + * Copyright (c) 2016 Quentin Schulz <quentin.schulz@free-electrons>
> + *
> + * 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.

Your wrapping is wrong.

> + */
> +
> +#include <linux/completion.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +#include <linux/iio/iio.h>
> +#include <linux/iio/driver.h>
> +#include <linux/iio/machine.h>
> +#include <linux/mfd/sunxi-gpadc-mfd.h>
> +
> +#define SUNXI_GPADC_TP_CTRL0 0x00
> +#define SUNXI_GPADC_TP_CTRL1 0x04
> +#define SUNXI_GPADC_TP_CTRL2 0x08
> +#define SUNXI_GPADC_TP_CTRL3 0x0c
> +#define SUNXI_GPADC_TP_TPR 0x18
> +#define SUNXI_GPADC_TP_CDAT 0x1c
> +#define SUNXI_GPADC_TEMP_DATA 0x20
> +#define SUNXI_GPADC_TP_DATA 0x24
> +
> +/* TP_CTRL0 bits */
> +#define SUNXI_GPADC_ADC_FIRST_DLY(x) ((x) << 24) /* 8 bits */
> +#define SUNXI_GPADC_ADC_FIRST_DLY_MODE BIT(23)
> +#define SUNXI_GPADC_ADC_CLK_SELECT BIT(22)
> +#define SUNXI_GPADC_ADC_CLK_DIVIDER(x) ((x) << 20) /* 2 bits */
> +#define SUNXI_GPADC_FS_DIV(x) ((x) << 16) /* 4 bits */
> +#define SUNXI_GPADC_T_ACQ(x) ((x) << 0) /* 16 bits */

We usually prefer to have the bits defined directly after the
registers, and prefixed with the name of the register they belong to.

Something like SUNXI_GPADC_TP_CTRL_T_ACQ in this case

> +
> +/* TP_CTRL1 bits */
> +#define SUNXI_GPADC_STYLUS_UP_DEBOUNCE(x) ((x) << 12) /* 8 bits */
> +#define SUNXI_GPADC_STYLUS_UP_DEBOUNCE_EN BIT(9)
> +#define SUNXI_GPADC_TOUCH_PAN_CALI_EN BIT(6)
> +#define SUNXI_GPADC_TP_DUAL_EN BIT(5)
> +#define SUNXI_GPADC_TP_MODE_EN BIT(4)
> +#define SUNXI_GPADC_TP_ADC_SELECT BIT(3)
> +#define SUNXI_GPADC_ADC_CHAN_SELECT(x) ((x) << 0) /* 3 bits */

Usually the comments are on the line above. However, if you really
want to enforce something, you should rather mask the
value. Otherwise, that comment is pretty useless.

> +
> +/* TP_CTRL1 bits for sun6i SOCs */
> +#define SUNXI_GPADC_SUN6I_TOUCH_PAN_CALI_EN BIT(7)
> +#define SUNXI_GPADC_SUN6I_TP_DUAL_EN BIT(6)
> +#define SUNXI_GPADC_SUN6I_TP_MODE_EN BIT(5)
> +#define SUNXI_GPADC_SUN6I_TP_ADC_SELECT BIT(4)

Shouldn't that go in either a common define or the touchscreen driver?

> +#define SUNXI_GPADC_SUN6I_ADC_CHAN_SELECT(x) BIT(x) /* 4 bits */



> +
> +/* TP_CTRL2 bits */
> +#define SUNXI_GPADC_TP_SENSITIVE_ADJUST(x) ((x) << 28) /* 4 bits */
> +#define SUNXI_GPADC_TP_MODE_SELECT(x) ((x) << 26) /* 2 bits */
> +#define SUNXI_GPADC_PRE_MEA_EN BIT(24)
> +#define SUNXI_GPADC_PRE_MEA_THRE_CNT(x) ((x) << 0) /* 24 bits */
> +
> +/* TP_CTRL3 bits */
> +#define SUNXI_GPADC_FILTER_EN BIT(2)
> +#define SUNXI_GPADC_FILTER_TYPE(x) ((x) << 0) /* 2 bits */
> +
> +/* TP_INT_FIFOC irq and fifo mask / control bits */
> +#define SUNXI_GPADC_TEMP_IRQ_EN BIT(18)
> +#define SUNXI_GPADC_TP_OVERRUN_IRQ_EN BIT(17)
> +#define SUNXI_GPADC_TP_DATA_IRQ_EN BIT(16)
> +#define SUNXI_GPADC_TP_DATA_XY_CHANGE BIT(13)
> +#define SUNXI_GPADC_TP_FIFO_TRIG_LEVEL(x) ((x) << 8) /* 5 bits */
> +#define SUNXI_GPADC_TP_DATA_DRQ_EN BIT(7)
> +#define SUNXI_GPADC_TP_FIFO_FLUSH BIT(4)
> +#define SUNXI_GPADC_TP_UP_IRQ_EN BIT(1)
> +#define SUNXI_GPADC_TP_DOWN_IRQ_EN BIT(0)
> +
> +/* TP_INT_FIFOS irq and fifo status bits */
> +#define SUNXI_GPADC_TEMP_DATA_PENDING BIT(18)
> +#define SUNXI_GPADC_FIFO_OVERRUN_PENDING BIT(17)
> +#define SUNXI_GPADC_FIFO_DATA_PENDING BIT(16)
> +#define SUNXI_GPADC_TP_IDLE_FLG BIT(2)
> +#define SUNXI_GPADC_TP_UP_PENDING BIT(1)
> +#define SUNXI_GPADC_TP_DOWN_PENDING BIT(0)
> +
> +/* TP_TPR bits */
> +#define SUNXI_GPADC_TEMP_ENABLE(x) ((x) << 16)
> +/* t = x * 256 * 16 / clkin */

That comment would be better next to the code that does that
computation.

> +#define SUNXI_GPADC_TEMP_PERIOD(x) ((x) << 0)
> +
> +#define SUNXI_GPADC_ARCH_SUN4I BIT(0)
> +#define SUNXI_GPADC_ARCH_SUN5I BIT(1)
> +#define SUNXI_GPADC_ARCH_SUN6I BIT(2)
> +
> +struct sunxi_gpadc_dev {
> + void __iomem *regs;
> + struct completion completion;
> + int temp_data;
> + u32 adc_data;
> + struct regmap *regmap;
> + unsigned int fifo_data_irq;
> + unsigned int temp_data_irq;
> + unsigned int flags;
> +};
> +
> +#define SUNXI_GPADC_ADC_CHANNEL(_channel, _name) { \
> + .type = IIO_VOLTAGE, \
> + .indexed = 1, \
> + .channel = _channel, \
> + .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
> + .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \
> + .datasheet_name = _name, \
> +}
> +
> +static struct iio_map sunxi_gpadc_hwmon_maps[] = {
> + {
> + .adc_channel_label = "temp_adc",
> + .consumer_dev_name = "iio_hwmon.0",
> + },
> + { /* sentinel */ },
> +};
> +
> +static const struct iio_chan_spec sunxi_gpadc_channels[] = {
> + SUNXI_GPADC_ADC_CHANNEL(0, "adc_chan0"),
> + SUNXI_GPADC_ADC_CHANNEL(1, "adc_chan1"),
> + SUNXI_GPADC_ADC_CHANNEL(2, "adc_chan2"),
> + SUNXI_GPADC_ADC_CHANNEL(3, "adc_chan3"),
> + {
> + .type = IIO_TEMP,
> + .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
> + .datasheet_name = "temp_adc",
> + .extend_name = "SoC temperature",
> + },
> + { /* sentinel */ },
> +};
> +
> +static int sunxi_gpadc_adc_read(struct iio_dev *indio_dev, int channel,
> + int *val)
> +{
> + struct sunxi_gpadc_dev *info = iio_priv(indio_dev);
> + int ret = 0;
> +
> + mutex_lock(&indio_dev->mlock);
> +
> + reinit_completion(&info->completion);
> + if (info->flags & SUNXI_GPADC_ARCH_SUN6I)
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL1,
> + SUNXI_GPADC_SUN6I_TP_MODE_EN |
> + SUNXI_GPADC_SUN6I_TP_ADC_SELECT |
> + SUNXI_GPADC_SUN6I_ADC_CHAN_SELECT(channel));
> + else
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL1,
> + SUNXI_GPADC_TP_MODE_EN |
> + SUNXI_GPADC_TP_ADC_SELECT |
> + SUNXI_GPADC_ADC_CHAN_SELECT(channel));

Using a function pointer that would compute this, or some fields in a
structure to store this would be better.

> + regmap_write(info->regmap, SUNXI_GPADC_TP_INT_FIFOC,
> + SUNXI_GPADC_TP_FIFO_TRIG_LEVEL(1) |
> + SUNXI_GPADC_TP_FIFO_FLUSH);
> + enable_irq(info->fifo_data_irq);
> +
> + if (!wait_for_completion_timeout(&info->completion,
> + msecs_to_jiffies(100))) {
> + ret = -ETIMEDOUT;
> + goto out;
> + }
> +
> + *val = info->adc_data;
> +
> +out:
> + disable_irq(info->fifo_data_irq);
> + mutex_unlock(&indio_dev->mlock);
> +
> + return ret;
> +}
> +
> +static int sunxi_gpadc_temp_read(struct iio_dev *indio_dev, int *val)
> +{
> + struct sunxi_gpadc_dev *info = iio_priv(indio_dev);
> + int ret = 0;
> +
> + mutex_lock(&indio_dev->mlock);
> +
> + reinit_completion(&info->completion);
> +
> + regmap_write(info->regmap, SUNXI_GPADC_TP_INT_FIFOC,
> + SUNXI_GPADC_TP_FIFO_TRIG_LEVEL(1) |
> + SUNXI_GPADC_TP_FIFO_FLUSH);
> + if (info->flags & SUNXI_GPADC_ARCH_SUN6I)
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL1,
> + SUNXI_GPADC_SUN6I_TP_MODE_EN);
> + else
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL1,
> + SUNXI_GPADC_TP_MODE_EN);
> + enable_irq(info->temp_data_irq);
> +
> + if (!wait_for_completion_timeout(&info->completion,
> + msecs_to_jiffies(100))) {
> + ret = -ETIMEDOUT;
> + goto out;
> + }
> +
> + if (info->flags & SUNXI_GPADC_ARCH_SUN4I)
> + *val = info->temp_data * 133 - 257000;
> + else if (info->flags & SUNXI_GPADC_ARCH_SUN5I)
> + *val = info->temp_data * 100 - 144700;
> + else if (info->flags & SUNXI_GPADC_ARCH_SUN6I)
> + *val = info->temp_data * 167 - 271000;

Ditto, having functions to comptue this and just store the function
pointer would be better.

> +
> +out:
> + disable_irq(info->temp_data_irq);
> + mutex_unlock(&indio_dev->mlock);
> +
> + return ret;
> +
> +}
> +
> +static int sunxi_gpadc_read_raw(struct iio_dev *indio_dev,
> + struct iio_chan_spec const *chan,
> + int *val, int *val2, long mask)
> +{
> + int ret;
> +
> + switch (mask) {
> + case IIO_CHAN_INFO_PROCESSED:
> + ret = sunxi_gpadc_temp_read(indio_dev, val);
> + if (ret)
> + return ret;
> +
> + return IIO_VAL_INT;
> + case IIO_CHAN_INFO_RAW:
> + ret = sunxi_gpadc_adc_read(indio_dev, chan->channel, val);
> + if (ret)
> + return ret;
> +
> + return IIO_VAL_INT;
> + default:
> + return -EINVAL;
> + }
> +
> + return -EINVAL;
> +}
> +
> +static const struct iio_info sunxi_gpadc_iio_info = {
> + .read_raw = sunxi_gpadc_read_raw,
> + .driver_module = THIS_MODULE,
> +};
> +
> +static irqreturn_t sunxi_gpadc_temp_data_irq_handler(int irq, void *dev_id)
> +{
> + struct sunxi_gpadc_dev *info = dev_id;
> + int ret;
> +
> + ret = regmap_read(info->regmap, SUNXI_GPADC_TEMP_DATA,
> + &info->temp_data);
> + if (ret == 0)
> + complete(&info->completion);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static irqreturn_t sunxi_gpadc_fifo_data_irq_handler(int irq, void *dev_id)
> +{
> + struct sunxi_gpadc_dev *info = dev_id;
> + int ret;
> +
> + ret = regmap_read(info->regmap, SUNXI_GPADC_TP_DATA, &info->adc_data);
> + if (ret == 0)
> + complete(&info->completion);
> +
> + return IRQ_HANDLED;
> +}
> +
> +static int sunxi_gpadc_probe(struct platform_device *pdev)
> +{
> + struct sunxi_gpadc_dev *info;
> + struct iio_dev *indio_dev;
> + int ret, irq;
> + struct sunxi_gpadc_mfd_dev *sunxi_gpadc_mfd_dev;
> +
> + sunxi_gpadc_mfd_dev = dev_get_drvdata(pdev->dev.parent);
> +
> + indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*info));
> + if (!indio_dev)
> + return -ENOMEM;
> +
> + info = iio_priv(indio_dev);
> +
> + info->regmap = sunxi_gpadc_mfd_dev->regmap;
> + 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 = &sunxi_gpadc_iio_info;
> + indio_dev->modes = INDIO_DIRECT_MODE;
> + indio_dev->num_channels = ARRAY_SIZE(sunxi_gpadc_channels);
> + indio_dev->channels = sunxi_gpadc_channels;
> +
> + info->flags = platform_get_device_id(pdev)->driver_data;
> +
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL0, SUNXI_GPADC_FS_DIV(7) |
> + SUNXI_GPADC_ADC_CLK_DIVIDER(2) | SUNXI_GPADC_T_ACQ(63));
> + if (info->flags & SUNXI_GPADC_ARCH_SUN6I)
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL1,
> + SUNXI_GPADC_SUN6I_TP_MODE_EN);
> + else
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL1,
> + SUNXI_GPADC_TP_MODE_EN);
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL3, SUNXI_GPADC_FILTER_EN |
> + SUNXI_GPADC_FILTER_TYPE(1));
> + regmap_write(info->regmap, SUNXI_GPADC_TP_TPR,
> + SUNXI_GPADC_TEMP_ENABLE(1) |
> + SUNXI_GPADC_TEMP_PERIOD(1953));
> +
> + irq = platform_get_irq_byname(pdev, "TEMP_DATA_PENDING");
> + if (irq < 0) {
> + dev_err(&pdev->dev,
> + "no TEMP_DATA_PENDING interrupt registered\n");
> + ret = irq;
> + goto err;
> + }
> +
> + irq = regmap_irq_get_virq(sunxi_gpadc_mfd_dev->regmap_irqc, irq);
> + ret = devm_request_any_context_irq(&pdev->dev, irq,
> + sunxi_gpadc_temp_data_irq_handler, 0,
> + "temp_data", info);
> + if (ret < 0) {
> + dev_err(&pdev->dev,
> + "could not request TEMP_DATA_PENDING interrupt: %d\n",
> + ret);
> + goto err;
> + }
> +
> + info->temp_data_irq = irq;
> + disable_irq(irq);
> +
> + irq = platform_get_irq_byname(pdev, "FIFO_DATA_PENDING");
> + if (irq < 0) {
> + dev_err(&pdev->dev,
> + "no FIFO_DATA_PENDING interrupt registered\n");
> + ret = irq;
> + goto err;
> + }
> +
> + irq = regmap_irq_get_virq(sunxi_gpadc_mfd_dev->regmap_irqc, irq);
> + ret = devm_request_any_context_irq(&pdev->dev, irq,
> + sunxi_gpadc_fifo_data_irq_handler,
> + 0, "fifo_data", info);
> + if (ret < 0) {
> + dev_err(&pdev->dev,
> + "could not request FIFO_DATA_PENDING interrupt: %d\n",
> + ret);
> + goto err;
> + }
> +
> + info->fifo_data_irq = irq;
> + disable_irq(irq);

request_irq starts with irq enabled, which means that you can have an
interrupt showing up between your call to request_irq and the
disable_irq.

How would that work?

> +
> + ret = iio_map_array_register(indio_dev, sunxi_gpadc_hwmon_maps);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "failed to register iio map array\n");
> + goto err;
> + }
> +
> + platform_set_drvdata(pdev, indio_dev);
> +
> + ret = iio_device_register(indio_dev);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "could not register the device\n");
> + iio_map_array_unregister(indio_dev);

That should go in a separate label.

> + goto err;
> + }
> +
> + return 0;
> +
> +err:
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL1, 0);
> + regmap_write(info->regmap, SUNXI_GPADC_TP_TPR, 0);

Why is that needed?

> + return ret;
> +}
> +
> +static int sunxi_gpadc_remove(struct platform_device *pdev)
> +{
> + struct sunxi_gpadc_dev *info;
> + struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +
> + info = iio_priv(indio_dev);
> + iio_device_unregister(indio_dev);
> + iio_map_array_unregister(indio_dev);
> + regmap_write(info->regmap, SUNXI_GPADC_TP_INT_FIFOC, 0);
> + regmap_write(info->regmap, SUNXI_GPADC_TP_CTRL1, 0);
> + regmap_write(info->regmap, SUNXI_GPADC_TP_TPR, 0);
> +
> + return 0;
> +}
> +
> +static const struct platform_device_id sunxi_gpadc_id[] = {
> + { "sun4i-a10-gpadc-iio", SUNXI_GPADC_ARCH_SUN4I },
> + { "sun5i-a13-gpadc-iio", SUNXI_GPADC_ARCH_SUN5I },
> + { "sun6i-a31-gpadc-iio", SUNXI_GPADC_ARCH_SUN6I },
> + { /* sentinel */ },
> +};
> +
> +static struct platform_driver sunxi_gpadc_driver = {
> + .driver = {
> + .name = "sunxi-gpadc-iio",
> + },
> + .id_table = sunxi_gpadc_id,
> + .probe = sunxi_gpadc_probe,
> + .remove = sunxi_gpadc_remove,
> +};

Having some runtime_pm support for this would be great too.

Thanks!
Maxime

--
Maxime Ripard, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com

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