Re: [PATCH RFC 3/4] input: touchscreen: add I2C support for Goodix Berlin Touchscreen IC

[Jeff LaBundy <jeff@labundy.com>]

Hi Neil,

Excellent work; just a few nits on this particular instance.

On Tue, Jun 06, 2023 at 04:31:58PM +0200, Neil Armstrong wrote:
> Add initial support for the new Goodix "Berlin" touchscreen ICs
> over the I2C interface.
> 
> This initial driver is derived from the Goodix goodix_ts_berlin
> available at [1] and [2] and only supports the GT9916 IC
> present on the Qualcomm SM8550 MTP & QRD touch panel.
> 
> The current implementation only supports BerlinD, aka GT9916.
> 
> [1] https://github.com/goodix/goodix_ts_berlin
> [2] https://git.codelinaro.org/clo/la/platform/vendor/opensource/touch-drivers
> 
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---
>  drivers/input/touchscreen/Kconfig             | 14 +++++
>  drivers/input/touchscreen/Makefile            |  1 +
>  drivers/input/touchscreen/goodix_berlin_i2c.c | 76 +++++++++++++++++++++++++++
>  3 files changed, 91 insertions(+)
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 1a6f6f6da991..da6d5d75c42d 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -421,6 +421,20 @@ config TOUCHSCREEN_GOODIX_BERLIN_CORE
>  	depends on REGMAP
>  	tristate
>  
> +config TOUCHSCREEN_GOODIX_BERLIN_I2C
> +	tristate "Goodix Berlin I2C touchscreen"
> +	depends on I2C
> +	depends on REGMAP_I2C

As you already depend upon REGMAP, I think you can simply select REGMAP_I2C
here instead of depending upon it as well.

> +	select TOUCHSCREEN_GOODIX_BERLIN_CORE
> +	help
> +	  Say Y here if you have the a touchscreen connected to your
> +	  system using the Goodix Berlin IC connection via I2C.

This language was a bit of a tongue-twister; perhaps it is better to say
"...if you have a Goodix Berlin IC connected to your system via I2C."

> +
> +	  If unsure, say N.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called goodix_berlin_i2c.
> +
>  config TOUCHSCREEN_HIDEEP
>  	tristate "HiDeep Touch IC"
>  	depends on I2C
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 29cdb042e104..921a2da0c2be 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -48,6 +48,7 @@ obj-$(CONFIG_TOUCHSCREEN_EXC3000)	+= exc3000.o
>  obj-$(CONFIG_TOUCHSCREEN_FUJITSU)	+= fujitsu_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_GOODIX)	+= goodix_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_CORE)	+= goodix_berlin_core.o
> +obj-$(CONFIG_TOUCHSCREEN_GOODIX_BERLIN_I2C)	+= goodix_berlin_i2c.o
>  obj-$(CONFIG_TOUCHSCREEN_HIDEEP)	+= hideep.o
>  obj-$(CONFIG_TOUCHSCREEN_HYNITRON_CSTXXX)	+= hynitron_cstxxx.o
>  obj-$(CONFIG_TOUCHSCREEN_ILI210X)	+= ili210x.o
> diff --git a/drivers/input/touchscreen/goodix_berlin_i2c.c b/drivers/input/touchscreen/goodix_berlin_i2c.c
> new file mode 100644
> index 000000000000..fc32b8077287
> --- /dev/null
> +++ b/drivers/input/touchscreen/goodix_berlin_i2c.c
> @@ -0,0 +1,76 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * Goodix Berlin Touchscreen Driver
> + *
> + * Copyright (C) 2020 - 2021 Goodix, Inc.
> + * Copyright (C) 2023 Linaro Ltd.
> + *
> + * Based on goodix_ts_berlin driver.
> + */
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/i2c.h>
> +#include <linux/regmap.h>
> +#include <asm/unaligned.h>

This last include does not seem to provide anything.

> +
> +#include "goodix_berlin.h"
> +
> +#define I2C_MAX_TRANSFER_SIZE		256
> +
> +static const struct regmap_config goodix_berlin_i2c_regmap_conf = {
> +	.reg_bits = 32,
> +	.val_bits = 8,
> +	.max_raw_read = I2C_MAX_TRANSFER_SIZE,
> +	.max_raw_write = I2C_MAX_TRANSFER_SIZE,
> +};
> +
> +static const struct input_id goodix_berlin_i2c_input_id = {
> +	.bustype = BUS_I2C,
> +	.vendor = 0x0416,
> +	.product = 0x1001,
> +};
> +
> +static int goodix_berlin_i2c_probe(struct i2c_client *client)
> +{
> +	struct regmap *map;

'regmap' tends to be more common than simply 'map'.

> +
> +	map = devm_regmap_init_i2c(client, &goodix_berlin_i2c_regmap_conf);
> +	if (IS_ERR(map))
> +		return PTR_ERR(map);
> +
> +	return goodix_berlin_probe(&client->dev, client->irq,
> +				   &goodix_berlin_i2c_input_id, map);
> +}
> +
> +static void goodix_berlin_i2c_remove(struct i2c_client *client)
> +{
> +	goodix_berlin_remove(&client->dev);
> +}
> +
> +static const struct i2c_device_id goodix_berlin_i2c_id[] = {
> +	{ "gt9916", 0 },
> +	{ }
> +};
> +
> +MODULE_DEVICE_TABLE(i2c, goodix_berlin_i2c_id);
> +
> +static const struct of_device_id goodix_berlin_i2c_of_match[] = {
> +	{ .compatible = "goodix,gt9916", },
> +	{ },

No need for a trailing comma following the sentinel.

> +};
> +
> +static struct i2c_driver goodix_berlin_i2c_driver = {
> +	.driver = {
> +		.name = "goodix-berlin-i2c",
> +		.of_match_table = goodix_berlin_i2c_of_match,
> +		.pm = pm_sleep_ptr(&goodix_berlin_pm_ops),
> +	},
> +	.probe = goodix_berlin_i2c_probe,
> +	.remove = goodix_berlin_i2c_remove,
> +	.id_table = goodix_berlin_i2c_id,
> +};
> +module_i2c_driver(goodix_berlin_i2c_driver);
> +
> +MODULE_LICENSE("GPL");
> +MODULE_DESCRIPTION("Goodix Berlin I2C Touchscreen driver");
> +MODULE_AUTHOR("Neil Armstrong <neil.armstrong@linaro.org>");
> 
> -- 
> 2.34.1
> 

Kind regards,
Jeff LaBundy