Re: [PATCH v4 4/4] HID: i2c-hid: Introduce goodix-i2c-hid as a subclass of i2c-hid

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 11/4/20 2:29 AM, Douglas Anderson wrote:
> Goodix i2c-hid touchscreens are mostly i2c-hid compliant but have some
> special power sequencing requirements, including the need to drive a
> reset line during the sequencing.
> 
> Let's use the new ability of i2c-hid to have subclasses for power
> sequencing to support the first Goodix i2c-hid touchscreen: GT7375P
> 
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> ---
> 
> Changes in v4:
> - Totally redid based on the new subclass system.

Again just my 2 cents, but I'm not sure if this should be an
entirely separate driver, or just something added to the
generic drivers/hid/i2c-hid/i2c-hid-of.c code.

I have no real preference either way, just asking the
question to make sure both options are considered.

Regards,

Hans




> Changes in v3:
> - Rework to use subclassing.
> 
>  drivers/hid/i2c-hid/Kconfig             |  19 +++-
>  drivers/hid/i2c-hid/Makefile            |   1 +
>  drivers/hid/i2c-hid/i2c-hid-of-goodix.c | 120 ++++++++++++++++++++++++
>  3 files changed, 138 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/hid/i2c-hid/i2c-hid-of-goodix.c
> 
> diff --git a/drivers/hid/i2c-hid/Kconfig b/drivers/hid/i2c-hid/Kconfig
> index 819b7521c182..a16c6a69680b 100644
> --- a/drivers/hid/i2c-hid/Kconfig
> +++ b/drivers/hid/i2c-hid/Kconfig
> @@ -32,10 +32,25 @@ config I2C_HID_OF
>  	  will be called i2c-hid-of.  It will also build/depend on the
>  	  module i2c-hid.
>  
> +config I2C_HID_OF_GOODIX
> +	tristate "Driver for Goodix hid-i2c based devices on OF systems"
> +	default n
> +	depends on I2C && INPUT && OF
> +	help
> +	  Say Y here if you want support for Goodix i2c devices that use
> +	  the i2c-hid protocol on Open Firmware (Device Tree)-based
> +	  systems.
> +
> +	  If unsure, say N.
> +
> +	  This support is also available as a module.  If so, the module
> +	  will be called i2c-hid-of-goodix.  It will also build/depend on
> +	  the module i2c-hid.
> +
>  endmenu
>  
>  config I2C_HID_CORE
>  	tristate
> -	default y if I2C_HID_ACPI=y || I2C_HID_OF=y
> -	default m if I2C_HID_ACPI=m || I2C_HID_OF=m
> +	default y if I2C_HID_ACPI=y || I2C_HID_OF=y || I2C_HID_OF_GOODIX=y
> +	default m if I2C_HID_ACPI=m || I2C_HID_OF=m || I2C_HID_OF_GOODIX=m
>  	select HID
> diff --git a/drivers/hid/i2c-hid/Makefile b/drivers/hid/i2c-hid/Makefile
> index 9b4a73446841..302545a771f3 100644
> --- a/drivers/hid/i2c-hid/Makefile
> +++ b/drivers/hid/i2c-hid/Makefile
> @@ -10,3 +10,4 @@ i2c-hid-$(CONFIG_DMI)				+= i2c-hid-dmi-quirks.o
>  
>  obj-$(CONFIG_I2C_HID_ACPI)			+= i2c-hid-acpi.o
>  obj-$(CONFIG_I2C_HID_OF)			+= i2c-hid-of.o
> +obj-$(CONFIG_I2C_HID_OF_GOODIX)			+= i2c-hid-of-goodix.o
> diff --git a/drivers/hid/i2c-hid/i2c-hid-of-goodix.c b/drivers/hid/i2c-hid/i2c-hid-of-goodix.c
> new file mode 100644
> index 000000000000..7b27fd8b7401
> --- /dev/null
> +++ b/drivers/hid/i2c-hid/i2c-hid-of-goodix.c
> @@ -0,0 +1,120 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Driver for Goodix touchscreens that use the i2c-hid protocol.
> + *
> + * Copyright 2020 Google LLC
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/gpio/consumer.h>
> +#include <linux/i2c.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/pm.h>
> +#include <linux/regulator/consumer.h>
> +
> +#include "i2c-hid.h"
> +
> +struct goodix_i2c_hid_timing_data {
> +	unsigned int post_gpio_reset_delay_ms;
> +	unsigned int post_power_delay_ms;
> +};
> +
> +struct i2c_hid_of_goodix {
> +	struct i2chid_subclass_data subclass;
> +
> +	struct regulator *vdd;
> +	struct gpio_desc *reset_gpio;
> +	const struct goodix_i2c_hid_timing_data *timings;
> +};
> +
> +static int goodix_i2c_hid_power_up_device(struct i2chid_subclass_data *subclass)
> +{
> +	struct i2c_hid_of_goodix *ihid_goodix =
> +		container_of(subclass, struct i2c_hid_of_goodix, subclass);
> +	int ret;
> +
> +	ret = regulator_enable(ihid_goodix->vdd);
> +	if (ret)
> +		return ret;
> +
> +	if (ihid_goodix->timings->post_power_delay_ms)
> +		msleep(ihid_goodix->timings->post_power_delay_ms);
> +
> +	gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 0);
> +	if (ihid_goodix->timings->post_gpio_reset_delay_ms)
> +		msleep(ihid_goodix->timings->post_gpio_reset_delay_ms);
> +
> +	return 0;
> +}
> +
> +static void goodix_i2c_hid_power_down_device(struct i2chid_subclass_data *subclass)
> +{
> +	struct i2c_hid_of_goodix *ihid_goodix =
> +		container_of(subclass, struct i2c_hid_of_goodix, subclass);
> +
> +	gpiod_set_value_cansleep(ihid_goodix->reset_gpio, 1);
> +	regulator_disable(ihid_goodix->vdd);
> +}
> +
> +static int i2c_hid_of_goodix_probe(struct i2c_client *client,
> +				   const struct i2c_device_id *id)
> +{
> +	struct i2c_hid_of_goodix *ihid_goodix;
> +
> +	ihid_goodix = devm_kzalloc(&client->dev, sizeof(*ihid_goodix),
> +				   GFP_KERNEL);
> +	if (!ihid_goodix)
> +		return -ENOMEM;
> +
> +	ihid_goodix->subclass.power_up_device = goodix_i2c_hid_power_up_device;
> +	ihid_goodix->subclass.power_down_device = goodix_i2c_hid_power_down_device;
> +
> +	/* Start out with reset asserted */
> +	ihid_goodix->reset_gpio =
> +		devm_gpiod_get_optional(&client->dev, "reset", GPIOD_OUT_HIGH);
> +	if (IS_ERR(ihid_goodix->reset_gpio))
> +		return PTR_ERR(ihid_goodix->reset_gpio);
> +
> +	ihid_goodix->vdd = devm_regulator_get(&client->dev, "vdd");
> +	if (IS_ERR(ihid_goodix->vdd))
> +		return PTR_ERR(ihid_goodix->vdd);
> +
> +	ihid_goodix->timings = device_get_match_data(&client->dev);
> +
> +	return i2c_hid_core_probe(client, &ihid_goodix->subclass, 0x0001);
> +}
> +
> +static const struct goodix_i2c_hid_timing_data goodix_gt7375p_timing_data = {
> +	.post_power_delay_ms = 10,
> +	.post_gpio_reset_delay_ms = 120,
> +};
> +
> +static const struct of_device_id goodix_i2c_hid_of_match[] = {
> +	{ .compatible = "goodix,gt7375p", .data = &goodix_gt7375p_timing_data },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, goodix_i2c_hid_of_match);
> +
> +static const struct dev_pm_ops goodix_i2c_hid_pm = {
> +	SET_SYSTEM_SLEEP_PM_OPS(i2c_hid_core_suspend, i2c_hid_core_resume)
> +};
> +
> +static struct i2c_driver goodix_i2c_hid_ts_driver = {
> +	.driver = {
> +		.name	= "i2c_hid_of_goodix",
> +		.pm	= &goodix_i2c_hid_pm,
> +		.probe_type = PROBE_PREFER_ASYNCHRONOUS,
> +		.of_match_table = of_match_ptr(goodix_i2c_hid_of_match),
> +	},
> +	.probe		= i2c_hid_of_goodix_probe,
> +	.remove		= i2c_hid_core_remove,
> +	.shutdown	= i2c_hid_core_shutdown,
> +};
> +module_i2c_driver(goodix_i2c_hid_ts_driver);
> +
> +MODULE_AUTHOR("Douglas Anderson <dianders@chromium.org>");
> +MODULE_DESCRIPTION("Goodix i2c-hid touchscreen driver");
> +MODULE_LICENSE("GPL v2");
>