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Subject: Re: [PATCH 2/2] iio: counter: Add support for Milbeaut Updown Counter
To:     Jonathan Cameron <jic23@kernel.org>
References: <1553582012-13563-1-git-send-email-kanematsu.shinji@socionext.com>
 <20190330184344.7c98aa58@archlinux>
From:   =?UTF-8?B?S2FuZW1hdHN1LCBTaGluamkv5YW85p2+IOS8uOasoQ==?= 
        <kanematsu.shinji@socionext.com>
Message-ID: <7da09583-2895-57dd-46fb-7656ddbfad2c@socionext.com>
Date:   Tue, 2 Apr 2019 14:30:27 +0900
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Hi Jonathan,

Thank you for your review.

On 2019/03/31 3:43, Jonathan Cameron wrote:
> On Tue, 26 Mar 2019 15:33:32 +0900
> Shinji Kanematsu <kanematsu.shinji@socionext.com> wrote:
> 
>> Add support for Milbeaut Updown Counter, that can be used as counter
>> or quadrature encoder.
>>
>> Signed-off-by: Shinji Kanematsu <kanematsu.shinji@socionext.com>
> A few minor comments inline.  The counter subsystem will provide a cleaner
> way of describing this. Please look to that for v2.
> 
> Hopefully William will give some feedback as well.
> 

OK, I understand.

> Jonathan
>> ---
>>   drivers/iio/counter/Kconfig               |  12 +
>>   drivers/iio/counter/Makefile              |   1 +
>>   drivers/iio/counter/milbeaut-updown.h     |  38 +++
>>   drivers/iio/counter/milbeaut-updown_cnt.c | 385 ++++++++++++++++++++++++++++++
>>   4 files changed, 436 insertions(+)
>>   create mode 100644 drivers/iio/counter/milbeaut-updown.h
>>   create mode 100644 drivers/iio/counter/milbeaut-updown_cnt.c
>>
>> diff --git a/drivers/iio/counter/Kconfig b/drivers/iio/counter/Kconfig
>> index bf1e559..a665f61 100644
>> --- a/drivers/iio/counter/Kconfig
>> +++ b/drivers/iio/counter/Kconfig
>> @@ -31,4 +31,16 @@ config STM32_LPTIMER_CNT
>>   
>>   	  To compile this driver as a module, choose M here: the
>>   	  module will be called stm32-lptimer-cnt.
>> +
>> +config MILBEAUT_UPDOWN_CNT
>> +	tristate "Milbeaut Updown Counter driver"
>> +	depends on OF
>> +	depends on ARCH_MILBEAUT || COMPILE_TEST
>> +	help
>> +	  Select this option to enable Milbeaut Updown Counter quadrature encoder
>> +	  and counter driver.
>> +
>> +	  To compile this driver as a module, choose M here: the
>> +	  module will be called milbeaut-updown-cnt.
>> +
>>   endmenu
>> diff --git a/drivers/iio/counter/Makefile b/drivers/iio/counter/Makefile
>> index 1b9a896..0cb708b 100644
>> --- a/drivers/iio/counter/Makefile
>> +++ b/drivers/iio/counter/Makefile
>> @@ -6,3 +6,4 @@
>>   
>>   obj-$(CONFIG_104_QUAD_8)	+= 104-quad-8.o
>>   obj-$(CONFIG_STM32_LPTIMER_CNT)	+= stm32-lptimer-cnt.o
>> +obj-$(CONFIG_MILBEAUT_UPDOWN_CNT)	+= milbeaut-updown_cnt.o
>> diff --git a/drivers/iio/counter/milbeaut-updown.h b/drivers/iio/counter/milbeaut-updown.h
>> new file mode 100644
>> index 0000000..9a038ad
>> --- /dev/null
>> +++ b/drivers/iio/counter/milbeaut-updown.h
>> @@ -0,0 +1,38 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +/*
>> + * Milbeaut Updown parent driver
>> + * Copyright (C) 2019 Socionext Inc.
>> + */
>> +
>> +#ifndef _LINUX_MILBEAUT_UPDOWN_H_
>> +#define _LINUX_MILBEAUT_UPDOWN_H_
>> +
>> +#define MLB_UPDOWN_UDCR		0x0		/* Updown Count Reg		*/
>> +#define MLB_UPDOWN_RCR		0x4		/* Reload Compare Reg	*/
>> +#define MLB_UPDOWN_CSR		0xC		/* Counter Status Reg	*/
>> +#define MLB_UPDOWN_CCR		0x14	/* Counter Control Reg	*/
>> +
>> +/* MLB_UPDOWN_CSR - bit fields */
>> +#define MLB_UPDOWN_CSTR		BIT(7)
>> +#define MLB_UPDOWN_UDIE		BIT(5)
>> +#define MLB_UPDOWN_CMPF		BIT(4)
>> +#define MLB_UPDOWN_OVFF		BIT(3)
>> +#define MLB_UPDOWN_UDFF		BIT(2)
>> +
>> +/* MLB_UPDOWN_CCR - bit fields */
>> +#define MLB_UPDOWN_FIXED	BIT(15)
>> +#define MLB_UPDOWN_CMS		GENMASK(11, 10)
>> +#define MLB_UPDOWN_CES		GENMASK(9, 8)
>> +#define MLB_UPDOWN_CTUT		BIT(6)
>> +#define MLB_UPDOWN_RLDE		BIT(4)
>> +
>> +/* MLB_UPDOWN max count value */
>> +#define MLB_UPDOWN_MAX_COUNT	0xFFFF
>> +
>> +/* MLB_UPDOWN rising edge detection */
>> +#define MLB_UPDOWN_RISING_EDGE		BIT(9)
>> +
>> +/* MLB_UPDOWN mode */
>> +#define MLB_UPDOWN_MODE		1
>> +
>> +#endif
>> diff --git a/drivers/iio/counter/milbeaut-updown_cnt.c b/drivers/iio/counter/milbeaut-updown_cnt.c
>> new file mode 100644
>> index 0000000..a58709a
>> --- /dev/null
>> +++ b/drivers/iio/counter/milbeaut-updown_cnt.c
>> @@ -0,0 +1,385 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Milbeaut Updown counter driver
>> + *
>> + * Copyright (C) 2019 Socionext Inc.
> I'm fussy about pointless lines.  The one below doesn't add anything ;)

That's right, correct it.

>> + *
>> + */
>> +
>> +#include <linux/bitfield.h>
>> +#include <linux/clk.h>
>> +#include <linux/iio/events.h>
>> +#include <linux/iio/iio.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/module.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/regmap.h>
>> +
>> +#include "milbeaut-updown.h"
>> +
>> +#define MILBEAUT_UPDOWN_IRQ_NAME		"milbeaut_updown_event"
>> +#define MILBEAUT_UPDOWN_MAX_REGISTER	0x1f
>> +
>> +static const struct regmap_config milbeaut_updown_regmap_cfg = {
>> +	.reg_bits = 32,
>> +	.val_bits = 32,
>> +	.reg_stride = sizeof(u32),
>> +	.max_register = MILBEAUT_UPDOWN_MAX_REGISTER,
>> +};
>> +struct milbeaut_updown_cnt {
>> +	struct device *dev;
>> +	struct regmap *regmap;
>> +	struct clk *clk;
>> +	u32 preset;
>> +	u32 polarity;
>> +	u32 quadrature_mode;
>> +};
>> +
>> +static int milbeaut_updown_is_enabled(struct milbeaut_updown_cnt *priv)
>> +{
>> +	u32 val;
>> +	int ret;
>> +
>> +	ret = regmap_read(priv->regmap, MLB_UPDOWN_CSR, &val);
>> +	if (ret)
>> +		return ret;
>> +
>> +	return FIELD_GET(MLB_UPDOWN_CSTR, val);
>> +}
>> +
>> +static int milbeaut_updown_setup(struct milbeaut_updown_cnt *priv,
>> +									int val)
>> +{
>> +	int ret;
>> +
>> +	if (val) {
>> +		ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CCR,
>> +				MLB_UPDOWN_CMS | MLB_UPDOWN_RLDE,
>> +				FIELD_PREP(MLB_UPDOWN_CMS, priv->quadrature_mode) |
>> +				MLB_UPDOWN_RLDE);
>> +		if (ret)
>> +			return ret;
>> +
>> +		if (priv->quadrature_mode == MLB_UPDOWN_MODE) {
>> +			ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CCR,
>> +					MLB_UPDOWN_CES, MLB_UPDOWN_RISING_EDGE);
>> +			if (ret)
>> +				return ret;
>> +		}
>> +
>> +		ret = regmap_write(priv->regmap, MLB_UPDOWN_RCR, priv->preset);
>> +		if (ret)
>> +			return ret;
>> +
>> +		/* interrupt */
>> +		ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CSR,
>> +						MLB_UPDOWN_UDIE, MLB_UPDOWN_UDIE);
>> +		if (ret)
>> +			return ret;
>> +
>> +		ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CCR,
>> +			MLB_UPDOWN_CTUT | MLB_UPDOWN_FIXED,
>> +			MLB_UPDOWN_CTUT | MLB_UPDOWN_FIXED);
>> +		if (ret)
>> +			return ret;
>> +
>> +		val = MLB_UPDOWN_CSTR;
>> +	}
>> +
>> +	return regmap_update_bits(priv->regmap, MLB_UPDOWN_CSR,
>> +								MLB_UPDOWN_CSTR, val);
>> +}
>> +
>> +static int milbeaut_updown_write_raw(struct iio_dev *indio_dev,
>> +				 struct iio_chan_spec const *chan,
>> +				 int val, int val2, long mask)
>> +{
>> +	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
>> +	int ret;
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_ENABLE:
>> +		if (val < 0 || val > 1)
>> +			return -EINVAL;
>> +
>> +		ret = milbeaut_updown_is_enabled(priv);
>> +		if (val && ret)
>> +			return -EBUSY;
>> +
>> +		ret = milbeaut_updown_setup(priv, val);
>> +
>> +		break;
>> +
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +
>> +	return ret;
>> +}
>> +
>> +static int milbeaut_updown_read_raw(struct iio_dev *indio_dev,
>> +				struct iio_chan_spec const *chan,
>> +				int *val, int *val2, long mask)
>> +{
>> +	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
>> +	u32 dat;
>> +	int ret;
>> +
>> +	switch (mask) {
>> +	case IIO_CHAN_INFO_RAW:
>> +		ret = regmap_read(priv->regmap, MLB_UPDOWN_UDCR, &dat);
>> +		if (ret)
>> +			return ret;
>> +		*val = dat;
>> +		return IIO_VAL_INT;
>> +
>> +	case IIO_CHAN_INFO_ENABLE:
>> +		ret = milbeaut_updown_is_enabled(priv);
>> +		if (ret < 0)
>> +			return ret;
>> +		*val = ret;
>> +		return IIO_VAL_INT;
>> +
>> +	default:
>> +		return -EINVAL;
>> +	}
>> +}
>> +
>> +static const struct iio_info milbeaut_updown_cnt_iio_info = {
>> +	.read_raw = milbeaut_updown_read_raw,
>> +	.write_raw = milbeaut_updown_write_raw,
>> +};
>> +
>> +static const char *const milbeaut_updown_quadrature_modes[] = {
>> +	"non-quadrature",
>> +	"quadrature",
>> +};
>> +
>> +static int milbeaut_updown_get_quadrature_mode(struct iio_dev *indio_dev,
>> +					   const struct iio_chan_spec *chan)
>> +{
>> +	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
>> +
>> +	return priv->quadrature_mode;
>> +}
>> +
>> +static int milbeaut_updown_set_quadrature_mode(struct iio_dev *indio_dev,
>> +					   const struct iio_chan_spec *chan,
>> +					   unsigned int type)
>> +{
>> +	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
>> +
>> +	if (milbeaut_updown_is_enabled(priv))
>> +		return -EBUSY;
>> +
>> +	priv->quadrature_mode = type;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct iio_enum milbeaut_updown_quadrature_mode_en = {
>> +	.items = milbeaut_updown_quadrature_modes,
>> +	.num_items = ARRAY_SIZE(milbeaut_updown_quadrature_modes),
>> +	.get = milbeaut_updown_get_quadrature_mode,
>> +	.set = milbeaut_updown_set_quadrature_mode,
>> +};
>> +
>> +static const char * const milbeaut_updown_cnt_polarity[] = {
>> +	"rising-edge", "falling-edge", "both-edges",
>> +};
>> +
>> +static int milbeaut_updown_cnt_get_polarity(struct iio_dev *indio_dev,
>> +					const struct iio_chan_spec *chan)
>> +{
>> +	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
>> +
>> +	return priv->polarity;
>> +}
>> +
>> +static int milbeaut_updown_cnt_set_polarity(struct iio_dev *indio_dev,
>> +					const struct iio_chan_spec *chan,
>> +					unsigned int type)
>> +{
>> +	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
>> +
>> +	if (milbeaut_updown_is_enabled(priv))
>> +		return -EBUSY;
>> +
>> +	priv->polarity = type;
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct iio_enum milbeaut_updown_cnt_polarity_en = {
>> +	.items = milbeaut_updown_cnt_polarity,
>> +	.num_items = ARRAY_SIZE(milbeaut_updown_cnt_polarity),
>> +	.get = milbeaut_updown_cnt_get_polarity,
>> +	.set = milbeaut_updown_cnt_set_polarity,
>> +};
>> +
>> +static ssize_t milbeaut_updown_cnt_get_preset(struct iio_dev *indio_dev,
>> +					  uintptr_t private,
>> +					  const struct iio_chan_spec *chan,
>> +					  char *buf)
>> +{
>> +	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
>> +
>> +	return snprintf(buf, PAGE_SIZE, "%u\n", priv->preset);
>> +}
>> +
>> +static ssize_t milbeaut_updown_cnt_set_preset(struct iio_dev *indio_dev,
>> +					  uintptr_t private,
>> +					  const struct iio_chan_spec *chan,
>> +					  const char *buf, size_t len)
>> +{
>> +	struct milbeaut_updown_cnt *priv = iio_priv(indio_dev);
>> +	u32 check_preset;
>> +	int ret;
>> +
>> +	if (milbeaut_updown_is_enabled(priv))
>> +		return -EBUSY;
>> +
>> +	ret = kstrtouint(buf, 0, &check_preset);
>> +	if (ret)
>> +		return ret;
>> +
>> +	if (check_preset > MLB_UPDOWN_MAX_COUNT)
>> +		return -EINVAL;
>> +
>> +	ret = kstrtouint(buf, 0, &priv->preset);
> This structure is a little unusual.
> priv->preset = check_preset and that can't result
> in an error.
> 

It is strange that I did not notice myself.

>> +	if (ret)
>> +		return ret;
>> +
>> +	return len;
>> +}
>> +
>> +static const struct iio_chan_spec_ext_info milbeaut_updown_cnt_ext_info[] = {
>> +	{
>> +		.name = "preset",
>> +		.shared = IIO_SEPARATE,
>> +		.read = milbeaut_updown_cnt_get_preset,
>> +		.write = milbeaut_updown_cnt_set_preset,
>> +	},
>> +	IIO_ENUM("polarity", IIO_SEPARATE, &milbeaut_updown_cnt_polarity_en),
>> +	IIO_ENUM_AVAILABLE("polarity", &milbeaut_updown_cnt_polarity_en),
>> +	{}
>> +};
>> +
>> +static const struct iio_event_spec milbeaut_updown_cnt_event = {
>> +	.type = IIO_EV_TYPE_ROC,
>> +	.dir = IIO_EV_DIR_RISING,
>> +	.mask_separate = BIT(IIO_EV_INFO_ENABLE),
>> +	.mask_shared_by_type = BIT(IIO_EV_INFO_VALUE),
>> +};
>> +
>> +static const struct iio_chan_spec milbeaut_updown_cnt_channels = {
>> +	.type = IIO_COUNT,
>> +	.channel = 0,
>> +	.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
>> +			      BIT(IIO_CHAN_INFO_ENABLE) |
>> +			      BIT(IIO_CHAN_INFO_SCALE),
>> +	.ext_info = milbeaut_updown_cnt_ext_info,
>> +	.indexed = 1,
>> +	.event_spec = &milbeaut_updown_cnt_event,
>> +	.num_event_specs = 1,
>> +};
>> +
>> +static irqreturn_t milbeaut_updown_event_handler(int irq, void *private)
>> +{
>> +	struct iio_dev *indio_dev = private;
>> +	struct milbeaut_updown_cnt *priv;
>> +	int ret;
>> +
>> +	priv = iio_priv(indio_dev);
>> +
>> +	ret = regmap_update_bits(priv->regmap, MLB_UPDOWN_CSR,
>> +			MLB_UPDOWN_CMPF | MLB_UPDOWN_OVFF | MLB_UPDOWN_UDFF,
>> +			0);
>> +	WARN_ON_ONCE(ret < 0);
>> +
>> +	iio_push_event(indio_dev,
>> +			       IIO_MOD_EVENT_CODE(IIO_INCLI, 0, 1,
>> +						  IIO_EV_TYPE_ROC, IIO_EV_DIR_RISING),
>> +			       iio_get_time_ns(indio_dev));
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static int milbeaut_updown_cnt_probe(struct platform_device *pdev)
>> +{
>> +	struct milbeaut_updown_cnt *priv;
>> +	struct iio_dev *indio_dev;
>> +	struct resource *res;
>> +	void __iomem *mmio;
>> +	int ret;
>> +	int irq;
>> +
>> +	indio_dev = devm_iio_device_alloc(&pdev->dev, sizeof(*priv));
>> +	if (!indio_dev)
>> +		return -ENOMEM;
>> +
>> +	priv = iio_priv(indio_dev);
>> +	priv->dev = &pdev->dev;
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	mmio = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(mmio))
>> +		return PTR_ERR(mmio);
>> +
>> +	priv->regmap = devm_regmap_init_mmio_clk(&pdev->dev, "mux", mmio,
>> +							  &milbeaut_updown_regmap_cfg);
>> +	if (IS_ERR(priv->regmap))
>> +		return PTR_ERR(priv->regmap);
>> +
>> +	priv->clk = devm_clk_get(&pdev->dev, NULL);
>> +	if (IS_ERR(priv->clk))
>> +		return PTR_ERR(priv->clk);
>> +
>> +	priv->preset = MLB_UPDOWN_MAX_COUNT;
>> +	ret = of_property_read_u32(priv->dev->of_node,
>> +				"cms_type", &priv->quadrature_mode);
>> +	if (ret)
>> +		return -ENODEV;
>> +
>> +	indio_dev->name = dev_name(&pdev->dev);
>> +	indio_dev->dev.parent = &pdev->dev;
>> +	indio_dev->dev.of_node = pdev->dev.of_node;
> Why set this. I don't think anything uses it?
> 

That's right, delete it.

>> +	indio_dev->info = &milbeaut_updown_cnt_iio_info;
>> +	indio_dev->channels = &milbeaut_updown_cnt_channels;
>> +	indio_dev->num_channels = 1;
>> +
>> +	/* setting request irq */
> The comment doesn't add anything not apparent directly from the code.

OK, delete it.

>> +	irq = platform_get_irq(pdev, 0);
>> +	ret = devm_request_threaded_irq(&pdev->dev, irq,
>> +			NULL, milbeaut_updown_event_handler,
>> +			IRQF_TRIGGER_RISING | IRQF_ONESHOT,
>> +			MILBEAUT_UPDOWN_IRQ_NAME, indio_dev);
>> +	if (ret < 0) {
>> +		pr_err("%s request irq failed\n", __func__);
>> +		return ret;
>> +	}
>> +
>> +	platform_set_drvdata(pdev, priv);
> Why? I'm not seeing calls to platform_get_drvdata.

That's right, delete it.

>> +
>> +	return devm_iio_device_register(&pdev->dev, indio_dev);
>> +}
>> +
>> +static const struct of_device_id milbeaut_updown_cnt_of_match[] = {
>> +	{ .compatible = "socionext,milbeaut-updown-counter", },
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(of, milbeaut_updown_cnt_of_match);
>> +
>> +static struct platform_driver milbeaut_updown_cnt_driver = {
>> +	.probe = milbeaut_updown_cnt_probe,
>> +	.driver = {
>> +		.name = "milbeaut-updown-counter",
>> +		.of_match_table = milbeaut_updown_cnt_of_match,
>> +	},
>> +};
>> +module_platform_driver(milbeaut_updown_cnt_driver);
>> +
>> +MODULE_AUTHOR("Shinji Kanematsu <kanematsu.shinji@socionext.com>");
>> +MODULE_DESCRIPTION("Milbeaut Updown counter");
>> +MODULE_ALIAS("platform:milbeaut_updown_counter");
>> +MODULE_LICENSE("GPL v2");
>