Subject: [PATCH v4 2/3] iio: adc: mt2701: Add Mediatek auxadc driver for mt2701.

From: [email-masked] (Jonathan Cameron)
Date: Mon, 18 Jul 2016 18:12:13 +0100

On 11/07/16 07:39, Zhiyong Tao wrote:
> Add Mediatek auxadc driver based on iio.
> It will register a device in iio and support iio.
> So thermal can read auxadc channel to sample data by iio device.
> It is tested successfully on mt2701 platform.
> Mt8173 and mt6577 platforms are not tested.
> But the expectation is compatible.
> 
> Signed-off-by: Zhiyong Tao <[email-masked]>
Looks good to me.  Couple of really minor points / questions inline...

Just one thing to confirm... (you probably already answered this!)
What are the units of the voltage channels?

Jonathan
> ---
>  drivers/iio/adc/Kconfig         |   13 ++
>  drivers/iio/adc/Makefile        |    1 +
>  drivers/iio/adc/mt6577_auxadc.c |  294 +++++++++++++++++++++++++++++++++++++++
>  3 files changed, 308 insertions(+)
>  create mode 100644 drivers/iio/adc/mt6577_auxadc.c
> 
> diff --git a/drivers/iio/adc/Kconfig b/drivers/iio/adc/Kconfig
> index 25378c5..14929fc 100644
> --- a/drivers/iio/adc/Kconfig
> +++ b/drivers/iio/adc/Kconfig
> @@ -305,6 +305,19 @@ config MCP3422
>  	  This driver can also be built as a module. If so, the module will be
>  	  called mcp3422.
>  
> +config MEDIATEK_MT6577_AUXADC
> +        tristate "MediaTek AUXADC driver"
> +        depends on ARCH_MEDIATEK || COMPILE_TEST
> +        depends on HAS_IOMEM
> +        help
> +          Say yes here to enable support for MediaTek mt65xx AUXADC.
> +
> +          The driver supports immediate mode operation to read from one of sixteen
> +          channels (external or internal).
> +
> +          This driver can also be built as a module. If so, the module will be
> +          called mt6577_auxadc.
> +
>  config MEN_Z188_ADC
>  	tristate "MEN 16z188 ADC IP Core support"
>  	depends on MCB
> diff --git a/drivers/iio/adc/Makefile b/drivers/iio/adc/Makefile
> index 38638d4..8306347 100644
> --- a/drivers/iio/adc/Makefile
> +++ b/drivers/iio/adc/Makefile
> @@ -30,6 +30,7 @@ obj-$(CONFIG_MAX1027) += max1027.o
>  obj-$(CONFIG_MAX1363) += max1363.o
>  obj-$(CONFIG_MCP320X) += mcp320x.o
>  obj-$(CONFIG_MCP3422) += mcp3422.o
> +obj-$(CONFIG_MEDIATEK_MT6577_AUXADC) += mt6577_auxadc.o
>  obj-$(CONFIG_MEN_Z188_ADC) += men_z188_adc.o
>  obj-$(CONFIG_MXS_LRADC) += mxs-lradc.o
>  obj-$(CONFIG_NAU7802) += nau7802.o
> diff --git a/drivers/iio/adc/mt6577_auxadc.c b/drivers/iio/adc/mt6577_auxadc.c
> new file mode 100644
> index 0000000..c7cc901
> --- /dev/null
> +++ b/drivers/iio/adc/mt6577_auxadc.c
> @@ -0,0 +1,294 @@
> +/*
> + * Copyright (c) 2016 MediaTek Inc.
> + * Author: Zhiyong Tao <[email-masked]>
> + *
> + * 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.
> + *
> + * 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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/iopoll.h>
> +#include <linux/io.h>
> +#include <linux/iio/iio.h>
> +
> +/* Register definitions */
> +#define MT6577_AUXADC_CON0                    0x00
> +#define MT6577_AUXADC_CON1                    0x04
> +#define MT6577_AUXADC_CON2                    0x10
> +#define MT6577_AUXADC_STA                     BIT(0)
> +
> +#define MT6577_AUXADC_DAT0                    0x14
> +#define MT6577_AUXADC_RDY0                    BIT(12)
> +
> +#define MT6577_AUXADC_MISC                    0x94
> +#define MT6577_AUXADC_PDN_EN                  BIT(14)
> +
> +#define MT6577_AUXADC_DAT_MASK                0xfff
> +#define MT6577_AUXADC_SLEEP_US                1000
> +#define MT6577_AUXADC_TIMEOUT_US              10000
> +#define MT6577_AUXADC_POWER_READY_MS          1
> +#define MT6577_AUXADC_SAMPLE_READY_US         25
> +
> +struct mt6577_auxadc_device {
> +	void __iomem *reg_base;
> +	struct clk *adc_clk;
> +	struct mutex lock;
> +};
> +
> +#define MT6577_AUXADC_CHANNEL(idx) {				    \
> +		.type = IIO_VOLTAGE,				    \
> +		.indexed = 1,					    \
> +		.channel = (idx),				    \
> +		.info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED), \
> +}
> +
> +static const struct iio_chan_spec mt6577_auxadc_iio_channels[] = {
> +	MT6577_AUXADC_CHANNEL(0),
> +	MT6577_AUXADC_CHANNEL(1),
> +	MT6577_AUXADC_CHANNEL(2),
> +	MT6577_AUXADC_CHANNEL(3),
> +	MT6577_AUXADC_CHANNEL(4),
> +	MT6577_AUXADC_CHANNEL(5),
> +	MT6577_AUXADC_CHANNEL(6),
> +	MT6577_AUXADC_CHANNEL(7),
> +	MT6577_AUXADC_CHANNEL(8),
> +	MT6577_AUXADC_CHANNEL(9),
> +	MT6577_AUXADC_CHANNEL(10),
> +	MT6577_AUXADC_CHANNEL(11),
> +	MT6577_AUXADC_CHANNEL(12),
> +	MT6577_AUXADC_CHANNEL(13),
> +	MT6577_AUXADC_CHANNEL(14),
> +	MT6577_AUXADC_CHANNEL(15),
> +};
> +
> +static int mt6577_auxadc_read(struct iio_dev *indio_dev,
> +			      struct iio_chan_spec const *chan)
> +{
> +	u32 rawdata, val;
> +	void __iomem *reg_channel;
> +	int ret;
> +	struct mt6577_auxadc_device *adc_dev = iio_priv(indio_dev);
> +
> +	reg_channel = adc_dev->reg_base + MT6577_AUXADC_DAT0 +
> +		      chan->channel * 0x04;
> +
> +	mutex_lock(&adc_dev->lock);
> +
> +	val = readl(adc_dev->reg_base + MT6577_AUXADC_CON1);
> +	val &= ~(1 << chan->channel);
> +	writel(val, adc_dev->reg_base + MT6577_AUXADC_CON1);
> +
> +	/* read channel and make sure old ready bit == 0 */
> +	ret = readl_poll_timeout(reg_channel, val,
> +				 ((val & MT6577_AUXADC_RDY0) == 0),
> +				 MT6577_AUXADC_SLEEP_US,
> +				 MT6577_AUXADC_TIMEOUT_US);
> +	if (ret < 0) {
> +		dev_err(indio_dev->dev.parent,
> +			"wait for channel[%d] ready bit clear time out\n",
> +			chan->channel);
> +
> +		mutex_unlock(&adc_dev->lock);
> +
> +		return -ETIMEDOUT;
> +	}
> +
> +	/* set bit to trigger sample */
> +	val = readl(adc_dev->reg_base + MT6577_AUXADC_CON1);
> +	val |= 1 << chan->channel;
> +	writel(val, adc_dev->reg_base + MT6577_AUXADC_CON1);
> +
> +	/* we must delay here for hardware sample channel data */
> +	udelay(MT6577_AUXADC_SAMPLE_READY_US);
> +
> +	/* check MTK_AUXADC_CON2 if auxadc is idle */
> +	ret = readl_poll_timeout(adc_dev->reg_base + MT6577_AUXADC_CON2, val,
> +				 ((val & MT6577_AUXADC_STA) == 0),
> +				 MT6577_AUXADC_SLEEP_US,
> +				 MT6577_AUXADC_TIMEOUT_US);
> +	if (ret < 0) {
> +		dev_err(indio_dev->dev.parent,
> +			"wait for auxadc idle time out\n");
> +
> +		mutex_unlock(&adc_dev->lock);
> +
> +		return -ETIMEDOUT;
> +	}
> +
> +	/* read channel and make sure ready bit == 1 */
> +	ret = readl_poll_timeout(reg_channel, val,
> +				 ((val & MT6577_AUXADC_RDY0) != 0),
> +				 MT6577_AUXADC_SLEEP_US,
> +				 MT6577_AUXADC_TIMEOUT_US);
> +	if (ret < 0) {
> +		dev_err(indio_dev->dev.parent,
> +			"wait for channel[%d] data ready time out\n",
> +			chan->channel);
> +
> +		mutex_unlock(&adc_dev->lock);
> +
> +		return -ETIMEDOUT;
> +	}
> +
> +	/* read data */
> +	rawdata = readl(reg_channel) & MT6577_AUXADC_DAT_MASK;
> +
> +	mutex_unlock(&adc_dev->lock);
> +
> +	return rawdata;
> +}
> +
> +static int mt6577_auxadc_read_raw(struct iio_dev *indio_dev,
> +				  struct iio_chan_spec const *chan,
> +				  int *val,
> +				  int *val2,
> +				  long info)
> +{
> +	switch (info) {
> +	case IIO_CHAN_INFO_PROCESSED:
> +		*val = mt6577_auxadc_read(indio_dev, chan);
> +		if (*val < 0) {
> +			dev_err(indio_dev->dev.parent,
> +				"failed to sample data on channel[%d]\n",
> +				chan->channel);
> +			return *val;
> +		}
> +		return IIO_VAL_INT;
> +
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +
> +static const struct iio_info mt6577_auxadc_info = {
> +	.driver_module = THIS_MODULE,
> +	.read_raw = &mt6577_auxadc_read_raw,
> +};
> +
> +static int mt6577_auxadc_probe(struct platform_device *pdev)
> +{
> +	struct mt6577_auxadc_device *adc_dev;
> +	unsigned long adc_clk_rate;
> +	struct resource *res;
> +	struct iio_dev *indio_dev;
> +	int ret;
> +	u32 val;
> +
> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*adc_dev));
> +	if (!indio_dev)
> +		return -ENOMEM;
> +
> +	adc_dev = iio_priv(indio_dev);
> +	indio_dev->dev.parent = &pdev->dev;
> +	indio_dev->name = dev_name(&pdev->dev);
> +	indio_dev->info = &mt6577_auxadc_info;
> +	indio_dev->modes = INDIO_DIRECT_MODE;
> +	indio_dev->channels = mt6577_auxadc_iio_channels;
> +	indio_dev->num_channels = ARRAY_SIZE(mt6577_auxadc_iio_channels);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	adc_dev->reg_base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(adc_dev->reg_base)) {
> +		dev_err(&pdev->dev, "failed to get auxadc base address.\n");
> +		return PTR_ERR(adc_dev->reg_base);
> +	}
> +
> +	adc_dev->adc_clk = devm_clk_get(&pdev->dev, "main");
> +	if (IS_ERR(adc_dev->adc_clk)) {
> +		dev_err(&pdev->dev, "failed to get auxadc clock\n");
> +		return PTR_ERR(adc_dev->adc_clk);
> +	}
> +
> +	ret = clk_prepare_enable(adc_dev->adc_clk);
> +	if (ret) {
> +		dev_err(&pdev->dev, "failed to enable auxadc clock\n");
> +		return ret;
> +	}
> +
> +	adc_clk_rate = clk_get_rate(adc_dev->adc_clk);
> +	if (!adc_clk_rate) {
> +		dev_err(&pdev->dev, "null clock rate!\n");
> +		goto err_disable_clk;
> +	}
> +
> +	mutex_init(&adc_dev->lock);
> +
> +	val = readl(adc_dev->reg_base + MT6577_AUXADC_MISC);
> +	val |= MT6577_AUXADC_PDN_EN;
> +	writel(val, adc_dev->reg_base + MT6577_AUXADC_MISC);
> +	mdelay(MT6577_AUXADC_POWER_READY_MS);
> +
> +	val = readl(adc_dev->reg_base + MT6577_AUXADC_MISC);
> +	if ((val & MT6577_AUXADC_PDN_EN) == 0) {
That's a high level of paranoia... Any reason to believe this might fail?
> +		dev_err(&pdev->dev, "failed to enable auxadc power!\n");
> +		goto err_disable_clk;
> +	}
> +
> +	platform_set_drvdata(pdev, indio_dev);
> +
> +	ret = iio_device_register(indio_dev);
> +	if (ret < 0) {
I'd have slightly preferred that this error unwind block was also
moved to on a goto.  Makes it easier to review as the error block then
matches remove (with expected differences!)  Really small point however.

> +		dev_err(&pdev->dev, "failed to register iio device!\n");
> +		val = readl(adc_dev->reg_base + MT6577_AUXADC_MISC);
> +		val &= ~MT6577_AUXADC_PDN_EN;
> +		writel(val, adc_dev->reg_base + MT6577_AUXADC_MISC);
> +		goto err_disable_clk;
> +	}
> +
> +	return 0;
> +
> +err_disable_clk:
> +	clk_disable_unprepare(adc_dev->adc_clk);
> +	return -EINVAL;
> +}
> +
> +static int mt6577_auxadc_remove(struct platform_device *pdev)
> +{
> +	struct iio_dev *indio_dev = platform_get_drvdata(pdev);
> +	struct mt6577_auxadc_device *adc_dev = iio_priv(indio_dev);
> +	u32 val;
> +
> +	iio_device_unregister(indio_dev);
> +
> +	val = readl(adc_dev->reg_base + MT6577_AUXADC_MISC);
> +	val &= ~MT6577_AUXADC_PDN_EN;
> +	writel(val, adc_dev->reg_base + MT6577_AUXADC_MISC);
> +
> +	clk_disable_unprepare(adc_dev->adc_clk);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id mt6577_auxadc_of_match[] = {
> +	{ .compatible = "mediatek,mt2701-auxadc", },
> +	{ .compatible = "mediatek,mt8173-auxadc", },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, mt6577_auxadc_of_match);
> +
> +static struct platform_driver mt6577_auxadc_driver = {
> +	.driver = {
> +		.name   = "mt6577-auxadc",
> +		.of_match_table = mt6577_auxadc_of_match,
> +	},
> +	.probe	= mt6577_auxadc_probe,
> +	.remove	= mt6577_auxadc_remove,
> +};
> +module_platform_driver(mt6577_auxadc_driver);
> +
> +MODULE_AUTHOR("Zhiyong Tao <[email-masked]>");
> +MODULE_DESCRIPTION("MTK AUXADC Device Driver");
> +MODULE_LICENSE("GPL v2");
>