Message-ID: <20170103185625.GC16032@dtor-ws>
Date:   Tue, 3 Jan 2017 10:56:25 -0800
From:   Dmitry Torokhov <dmitry.torokhov@...il.com>
To:     Javier Martinez Canillas <javier@....samsung.com>
Cc:     Jaechul Lee <jcsing.lee@...sung.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will.deacon@....com>,
        Kukjin Kim <kgene@...nel.org>,
        Krzysztof Kozlowski <krzk@...nel.org>,
        Andi Shyti <andi.shyti@...sung.com>,
        Chanwoo Choi <cw00.choi@...sung.com>, beomho.seo@...sung.com,
        galaxyra@...il.com, linux-arm-kernel@...ts.infradead.org,
        linux-input@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org
Subject: Re: [PATCH 2/4] input: tm2-touchkey: Add touchkey driver support for
 TM2

On Tue, Jan 03, 2017 at 10:11:39AM -0300, Javier Martinez Canillas wrote:
> Hello Jaechul,
> 
> On 01/03/2017 04:57 AM, Jaechul Lee wrote:
> > This patch adds support for the TM2 touch key and led
> > functionlity.
> > 
> 
> s/functionlity/functionality
> 
> > The driver interfaces with userspace through an input device and
> > reports KEY_PHONE and KEY_BACK event types. LED brightness can be
> > controlled by "/sys/class/leds/tm2-touchkey/brightness".
> > 
> > Signed-off-by: Jaechul Lee <jcsing.lee@...sung.com>
> > Signed-off-by: Beomho Seo <beomho.seo@...sung.com>
> > ---
> >  drivers/input/keyboard/Kconfig        |  11 ++
> >  drivers/input/keyboard/Makefile       |   1 +
> >  drivers/input/keyboard/tm2-touchkey.c | 326 ++++++++++++++++++++++++++++++++++
> >  3 files changed, 338 insertions(+)
> >  create mode 100644 drivers/input/keyboard/tm2-touchkey.c
> > 
> > diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
> > index cbd75cf..72c0ba1 100644
> > --- a/drivers/input/keyboard/Kconfig
> > +++ b/drivers/input/keyboard/Kconfig
> > @@ -666,6 +666,17 @@ config KEYBOARD_TC3589X
> >  	  To compile this driver as a module, choose M here: the
> >  	  module will be called tc3589x-keypad.
> >  
> > +config KEYBOARD_TM2_TOUCHKEY
> > +	tristate "tm2-touchkey support"
> > +	depends on I2C

There should be LED dependency as well.

> > +	help
> > +	  Say Y here to enable the tm2-touchkey.
> > +	  touchkey driver for tm2. This driver can enable
> > +	  the interrupt and make input events and control led brightness.
> > +
> > +	  To compile this driver as a module, choose M here.
> > +	  module will be called tm2-touchkey
> > +
> >  config KEYBOARD_TWL4030
> >  	tristate "TI TWL4030/TWL5030/TPS659x0 keypad support"
> >  	depends on TWL4030_CORE
> > diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
> > index d9f4cfc..7d9acff 100644
> > --- a/drivers/input/keyboard/Makefile
> > +++ b/drivers/input/keyboard/Makefile
> > @@ -61,6 +61,7 @@ obj-$(CONFIG_KEYBOARD_SUN4I_LRADC)	+= sun4i-lradc-keys.o
> >  obj-$(CONFIG_KEYBOARD_SUNKBD)		+= sunkbd.o
> >  obj-$(CONFIG_KEYBOARD_TC3589X)		+= tc3589x-keypad.o
> >  obj-$(CONFIG_KEYBOARD_TEGRA)		+= tegra-kbc.o
> > +obj-$(CONFIG_KEYBOARD_TM2_TOUCHKEY)	+= tm2-touchkey.o
> >  obj-$(CONFIG_KEYBOARD_TWL4030)		+= twl4030_keypad.o
> >  obj-$(CONFIG_KEYBOARD_XTKBD)		+= xtkbd.o
> >  obj-$(CONFIG_KEYBOARD_W90P910)		+= w90p910_keypad.o
> > diff --git a/drivers/input/keyboard/tm2-touchkey.c b/drivers/input/keyboard/tm2-touchkey.c
> > new file mode 100644
> > index 0000000..d9575d8
> > --- /dev/null
> > +++ b/drivers/input/keyboard/tm2-touchkey.c
> > @@ -0,0 +1,326 @@
> > +/*
> > + * Driver for keys on GPIO lines capable of generating interrupts.

This does not match what the driver does.

> > + *
> > + * Copyright 2005 Phil Blundell
> > + * Copyright 2016 Samsung Electronics Co., Ltd.
> > + *
> > + * Author: Beomho Seo <beomho.seo@...sung.com>
> > + * Author: Jaechul Lee <jcsing.lee@...sung.com>
> > + *
> > + * 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.
> > + */
> > +
> > +#include <linux/bitops.h>
> > +#include <linux/delay.h>
> > +#include <linux/device.h>
> > +#include <linux/i2c.h>
> > +#include <linux/input.h>
> > +#include <linux/interrupt.h>
> > +#include <linux/irq.h>
> > +#include <linux/leds.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/pm.h>
> > +#include <linux/regulator/consumer.h>
> > +#include <linux/workqueue.h>
> > +
> > +#define TM2_TOUCHKEY_DEV_NAME			"tm2-touchkey"
> > +#define TM2_TOUCHKEY_KEYCODE_REG			0x03
> > +#define TM2_TOUCHKEY_BASE_REG			0x00
> > +#define TM2_TOUCHKEY_CMD_LED_ON			0x10
> > +#define TM2_TOUCHKEY_CMD_LED_OFF			0x20
> > +#define TM2_TOUCHKEY_BIT_PRESS_EV			BIT(3)
> > +#define TM2_TOUCHKEY_BIT_KEYCODE			GENMASK(2, 0)
> > +#define TM2_TOUCHKEY_LED_VOLTAGE_MIN			2500000
> > +#define TM2_TOUCHKEY_LED_VOLTAGE_MAX			3300000
> > +
> > +enum {
> > +	TM2_TOUCHKEY_KEY_MENU = 0x1,
> > +	TM2_TOUCHKEY_KEY_BACK,
> > +};
> > +
> > +#define tm2_touchkey_power_enable(x) __tm2_touchkey_power_onoff(x, 1)
> > +#define tm2_touchkey_power_disable(x) __tm2_touchkey_power_onoff(x, 0)
> > +
> > +struct tm2_touchkey_data {
> > +	struct i2c_client *client;
> > +	struct input_dev *input_dev;
> > +	struct led_classdev led_dev;
> > +
> > +	u8 keycode_type;
> > +	u8 pressed;
> > +	struct work_struct irq_work;
> > +
> > +	bool power_onoff;
> > +	struct regulator *regulator_vcc;	/* 1.8V */
> > +	struct regulator *regulator_vdd;	/* 3.3V */
> > +};
> > +
> > +static void tm2_touchkey_led_brightness_set(struct led_classdev *led_dev,
> > +						enum led_brightness brightness)
> > +{
> > +	struct tm2_touchkey_data *samsung_touchkey =

Just call it "touchkey", "samsung_touchkey" is too long for a local
variable.

> > +	    container_of(led_dev, struct tm2_touchkey_data, led_dev);
> > +	u32 volt;
> > +	u8 data;
> > +
> > +	if (brightness == LED_OFF) {
> > +		volt = TM2_TOUCHKEY_LED_VOLTAGE_MIN;
> > +		data = TM2_TOUCHKEY_CMD_LED_OFF;
> > +	} else {
> > +		volt = TM2_TOUCHKEY_LED_VOLTAGE_MAX;
> > +		data = TM2_TOUCHKEY_CMD_LED_ON;
> > +	}
> > +
> > +	regulator_set_voltage(samsung_touchkey->regulator_vdd, volt, volt);
> > +	i2c_smbus_write_byte_data(samsung_touchkey->client,
> > +				  TM2_TOUCHKEY_BASE_REG, data);
> > +}
> > +
> > +static int __tm2_touchkey_power_onoff(struct tm2_touchkey_data
> > +					  *samsung_touchkey, bool onoff)
> > +{
> > +	int ret = 0;
> > +
> > +	if (samsung_touchkey->power_onoff == onoff)
> > +		return ret;
> > +
> > +	if (onoff) {
> > +		ret = regulator_enable(samsung_touchkey->regulator_vcc);
> > +		if (ret)
> > +			return ret;
> > +
> > +		ret = regulator_enable(samsung_touchkey->regulator_vdd);
> > +		if (ret) {
> > +			regulator_disable(samsung_touchkey->regulator_vcc);
> > +			return ret;
> > +		}
> 
> I would add a comment about the sleep here.

Also "bulk" regulator API can be useful here.

> 
> > +		msleep(150);
> > +	} else {
> > +		int err;
> > +
> > +		err = regulator_disable(samsung_touchkey->regulator_vcc);
> > +		if (err)
> > +			ret = err;
> > +
> > +		err = regulator_disable(samsung_touchkey->regulator_vdd);
> > +		if (err && !ret)
> > +			ret = err;
> > +	}
> > +	samsung_touchkey->power_onoff = onoff;
> > +
> > +	return ret;
> > +}
> > +
> > +static void tm2_touchkey_irq_work(struct work_struct *irq_work)
> > +{
> > +	struct tm2_touchkey_data *samsung_touchkey =
> > +	    container_of(irq_work, struct tm2_touchkey_data, irq_work);
> > +
> > +	if (!samsung_touchkey->pressed) {
> > +		input_report_key(samsung_touchkey->input_dev, KEY_PHONE, 0);
> > +		input_report_key(samsung_touchkey->input_dev, KEY_BACK, 0);
> > +	} else {
> > +		if (samsung_touchkey->keycode_type == TM2_TOUCHKEY_KEY_MENU)
> > +			input_report_key(samsung_touchkey->input_dev,
> > +					 KEY_PHONE, 1);
> > +		else
> > +			input_report_key(samsung_touchkey->input_dev,
> > +					 KEY_BACK, 1);
> > +	}
> > +	input_sync(samsung_touchkey->input_dev);
> > +}

There is absolutely no reason for doing this in a work. Just call
input_report_key/input_sync from your threaded IRQ routine.

> > +
> > +static irqreturn_t tm2_touchkey_irq_handler(int irq, void *devid)
> > +{
> > +	struct tm2_touchkey_data *samsung_touchkey = devid;
> > +	u32 data;
> > +
> > +	data = i2c_smbus_read_byte_data(samsung_touchkey->client,
> > +					TM2_TOUCHKEY_KEYCODE_REG);
> > +
> > +	if (data < 0) {
> > +		dev_err(&samsung_touchkey->client->dev, "Failed to read i2c data\n");
> > +		return IRQ_HANDLED;
> > +	}
> > +
> > +	samsung_touchkey->keycode_type = data & TM2_TOUCHKEY_BIT_KEYCODE;
> > +	samsung_touchkey->pressed = !(data & TM2_TOUCHKEY_BIT_PRESS_EV);
> > +
> > +	if (samsung_touchkey->keycode_type != TM2_TOUCHKEY_KEY_MENU &&
> > +	    samsung_touchkey->keycode_type != TM2_TOUCHKEY_KEY_BACK)
> 
> Shouldn't at least a debug message be printed here so the user can
> know that an error occurred and a correct keycode was not received?
> 
> > +		return IRQ_HANDLED;
> > +
> > +	schedule_work(&samsung_touchkey->irq_work);
> > +
> > +	return IRQ_HANDLED;
> > +}
> > +
> > +static int tm2_touchkey_probe(struct i2c_client *client,
> > +				  const struct i2c_device_id *id)
> > +{
> > +	struct tm2_touchkey_data *samsung_touchkey;
> > +	int ret;
> > +
> > +	ret = i2c_check_functionality(client->adapter,
> > +				      I2C_FUNC_SMBUS_BYTE |
> > +				      I2C_FUNC_SMBUS_BYTE_DATA);
> > +	if (!ret) {
> > +		dev_err(&client->dev, "No I2C functionality found\n");
> > +		return -ENODEV;
> > +	}
> > +
> > +	samsung_touchkey = devm_kzalloc(&client->dev,
> > +			sizeof(struct tm2_touchkey_data), GFP_KERNEL);

sizeof(*touchkey)

> > +
> > +	if (!samsung_touchkey) {
> > +		dev_err(&client->dev, "Failed to allocate memory.\n");
> > +		return -ENOMEM;
> > +	}
> > +
> > +	samsung_touchkey->client = client;
> > +	i2c_set_clientdata(client, samsung_touchkey);
> > +	INIT_WORK(&samsung_touchkey->irq_work, tm2_touchkey_irq_work);

Work is not needed.

> > +
> > +	/* regulator */
> > +	samsung_touchkey->regulator_vcc =
> > +				devm_regulator_get(&client->dev, "vcc");
> > +	if (IS_ERR(samsung_touchkey->regulator_vcc)) {
> > +		dev_err(&client->dev, "Failed to get vcc regulator\n");
> > +		return PTR_ERR(samsung_touchkey->regulator_vcc);
> > +	}
> > +
> > +	samsung_touchkey->regulator_vdd =
> > +				devm_regulator_get(&client->dev, "vdd");
> > +	if (IS_ERR(samsung_touchkey->regulator_vdd)) {
> > +		dev_err(&client->dev, "Failed to get vdd regulator\n");
> > +		return PTR_ERR(samsung_touchkey->regulator_vcc);
> > +	}

devm_regulator_bulk_get

> > +
> > +	/* power */
> > +	ret = tm2_touchkey_power_enable(samsung_touchkey);
> > +	if (ret) {
> > +		dev_err(&client->dev, "Failed to enable power\n");
> > +		return ret;
> > +	}

You need to install devm action (devm_add_action_or_reset) to disable
power when unloading driver (or if initialization fails).

> > +
> > +	/* irq */
> > +	ret = devm_request_threaded_irq(&client->dev,
> > +					client->irq, NULL,
> > +					tm2_touchkey_irq_handler,
> > +					IRQF_TRIGGER_FALLING | IRQF_ONESHOT,

I'd rather we rely on IRQ trigger from DT, so just use IRQF_PNESHOT
here.

I'd rather you allocated input device before requesting IRQ. The
registering input device is fine to do after getting IRQ.

> > +					TM2_TOUCHKEY_DEV_NAME,
> > +					samsung_touchkey);
> > +	if (ret) {
> > +		dev_err(&client->dev, "Failed to request threaded irq\n");
> > +		return ret;
> > +	}
> > +
> > +	/* input device */
> > +	samsung_touchkey->input_dev = devm_input_allocate_device(&client->dev);
> > +	if (!samsung_touchkey->input_dev) {
> > +		dev_err(&client->dev, "Failed to alloc input device.\n");
> > +		return -ENOMEM;
> > +	}
> > +	samsung_touchkey->input_dev->name = TM2_TOUCHKEY_DEV_NAME;
> > +	samsung_touchkey->input_dev->id.bustype = BUS_I2C;
> > +	samsung_touchkey->input_dev->dev.parent = &client->dev;

No need to set parent when using devm_input_allocate_device(), it is
done automatically.

> > +
> > +	set_bit(EV_KEY, samsung_touchkey->input_dev->evbit);
> > +	set_bit(KEY_PHONE, samsung_touchkey->input_dev->keybit);
> > +	set_bit(KEY_BACK, samsung_touchkey->input_dev->keybit);


Just do
	input_set_capability(touchkey->input_dev, EV_KEY, KEY_PHONE);
	input_set_capability(touchkey->input_dev, EV_KEY, KEY_BACK);


> > +	input_set_drvdata(samsung_touchkey->input_dev, samsung_touchkey);
> > +
> > +	ret = input_register_device(samsung_touchkey->input_dev);
> > +	if (ret) {
> > +		dev_err(&client->dev, "Failed to register input device.\n");
> > +		return ret;
> > +	}
> > +
> > +	/* led device */
> > +	samsung_touchkey->led_dev.name = TM2_TOUCHKEY_DEV_NAME;
> > +	samsung_touchkey->led_dev.brightness = LED_FULL;
> > +	samsung_touchkey->led_dev.max_brightness = LED_FULL;
> > +	samsung_touchkey->led_dev.brightness_set =
> > +						tm2_touchkey_led_brightness_set;
> > +
> > +	ret = devm_led_classdev_register(&client->dev,
> > +					 &samsung_touchkey->led_dev);
> > +	if (ret < 0) {
> > +		dev_err(&client->dev, "Failed to register touchkey led\n");
> > +		return ret;
> > +	}
> > +
> > +	return 0;
> > +}
> > +
> > +static void tm2_touchkey_shutdown(struct i2c_client *client)
> > +{

This is something not normally done. Does your platform really keep
rails on when AP is off?

> > +	struct tm2_touchkey_data *samsung_touchkey =
> > +						i2c_get_clientdata(client);
> > +	int ret;
> > +
> > +	disable_irq(client->irq);
> > +	ret = tm2_touchkey_power_disable(samsung_touchkey);
> > +	if (ret)
> > +		dev_err(&client->dev, "Failed to disable power\n");
> > +}
> > +
> > +static int tm2_touchkey_suspend(struct device *dev)

__maybe_unused

> > +{
> > +	struct tm2_touchkey_data *samsung_touchkey = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	disable_irq(samsung_touchkey->client->irq);
> > +	ret = tm2_touchkey_power_disable(samsung_touchkey);
> > +	if (ret)
> > +		dev_err(dev, "Failed to disable power\n");
> > +
> > +	return ret;
> > +}
> 
> These two functions are basically the same, can you factor it out?
> 
> > +
> > +static int tm2_touchkey_resume(struct device *dev)

__maybe_unused

> > +{
> > +	struct tm2_touchkey_data *samsung_touchkey = dev_get_drvdata(dev);
> > +	int ret;
> > +
> > +	enable_irq(samsung_touchkey->client->irq);
> > +	ret = tm2_touchkey_power_enable(samsung_touchkey);
> > +	if (ret)
> > +		dev_err(dev, "Failed to enable power\n");
> > +
> > +	return ret;
> > +}
> > +
> > +static SIMPLE_DEV_PM_OPS(tm2_touchkey_pm_ops, tm2_touchkey_suspend,
> > +							tm2_touchkey_resume);
> > +
> > +static const struct i2c_device_id tm2_touchkey_id_table[] = {
> > +	{TM2_TOUCHKEY_DEV_NAME, 0},
> > +	{},
> > +};
> > +
> 
> You need a MODULE_DEVICE_TABLE(i2c, tm2_touchkey_id_table) here so the
> module can be autoloaded when the device is registered.
> 
> > +static const struct of_device_id tm2_touchkey_of_match[] = {
> > +	{.compatible = "samsung,tm2-touchkey",},
> > +	{},
> > +};
> > +
> 
> Here a MODULE_DEVICE_TABLE(of, tm2_touchkey_of_match) is not strictly
> needed since the I2C core always reports MODALIAS of the form i2c:<dev>
> but still is good to have so the I2C core can be fixed at some point.

Yes, please add MODULE_DEVICE_TABLE(of, ...).

> 
> > +static struct i2c_driver tm2_touchkey_driver = {
> > +	.driver = {
> > +		.name = TM2_TOUCHKEY_DEV_NAME,
> > +		.pm = &tm2_touchkey_pm_ops,
> > +		.of_match_table = of_match_ptr(tm2_touchkey_of_match),
> > +	},
> > +	.probe = tm2_touchkey_probe,
> > +	.shutdown = tm2_touchkey_shutdown,
> > +	.id_table = tm2_touchkey_id_table,
> > +};
> > +
> > +module_i2c_driver(tm2_touchkey_driver);
> > +
> > +MODULE_AUTHOR("Beomho Seo <beomho.seo@...sung.com>");
> > +MODULE_AUTHOR("Jaechul Lee <jcsing.lee@...sung.com>");
> > +MODULE_DESCRIPTION("Samsung touchkey driver");
> > +MODULE_LICENSE("GPL v2");
> > 

Thanks.

-- 
Dmitry

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