Re: [PATCH v2 2/4] Input: icn8318 - Add support for icn8505

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

On Sun, Jun 18, 2017 at 12:18:27PM +0200, Hans de Goede wrote:
> The icn8505 variant found on some x86 tablets has almost the same protocol
> as the 8318, protocol wise there are only a few small differences:
> 
> 1) The 8505 uses 16 bit register addresses and has a different register
> address for the location of the touch data.
> 2) The 8505 coordinates are in little-endian format instead of in be.
> 3) The 8505 allows reading the resolution back from the controller
> 
> Signed-off-by: Hans de Goede <hdegoede@redhat.com>
> ---
> Changes in v2:
> -Read resolution directly from the controller
> ---
>  .../bindings/input/touchscreen/chipone_icn8318.txt |  2 +-
>  drivers/input/touchscreen/Kconfig                  |  3 +-
>  drivers/input/touchscreen/chipone_icn8318.c        | 81 ++++++++++++++++++----
>  3 files changed, 69 insertions(+), 17 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/input/touchscreen/chipone_icn8318.txt b/Documentation/devicetree/bindings/input/touchscreen/chipone_icn8318.txt
> index d11f8d615b5d..9fdd80749386 100644
> --- a/Documentation/devicetree/bindings/input/touchscreen/chipone_icn8318.txt
> +++ b/Documentation/devicetree/bindings/input/touchscreen/chipone_icn8318.txt
> @@ -1,7 +1,7 @@
>  * ChipOne icn8318 I2C touchscreen controller
>  
>  Required properties:
> - - compatible		  : "chipone,icn8318"
> + - compatible		  : "chipone,icn8318" or "chipone,icn8505"
>   - reg			  : I2C slave address of the chip (0x40)
>   - interrupt-parent	  : a phandle pointing to the interrupt controller
>  			    serving the interrupt for this chip
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index cf26ca49ae6d..fff1467506e7 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -157,7 +157,8 @@ config TOUCHSCREEN_CHIPONE_ICN8318
>  	depends on I2C
>  	depends on OF
>  	help
> -	  Say Y here if you have a ChipOne icn8318 based I2C touchscreen.
> +	  Say Y here if you have a ChipOne icn8318 or icn8505 based
> +	  I2C touchscreen.
>  
>  	  If unsure, say N.
>  
> diff --git a/drivers/input/touchscreen/chipone_icn8318.c b/drivers/input/touchscreen/chipone_icn8318.c
> index ddaae91f02fc..43cc38734d8e 100644
> --- a/drivers/input/touchscreen/chipone_icn8318.c
> +++ b/drivers/input/touchscreen/chipone_icn8318.c
> @@ -1,7 +1,7 @@
>  /*
>   * Driver for ChipOne icn8318 i2c touchscreen controller
>   *
> - * Copyright (c) 2015 Red Hat Inc.
> + * Copyright (c) 2015-2017 Red Hat Inc.
>   *
>   * This program is free software; you can redistribute it and/or modify
>   * it under the terms of the GNU General Public License as published by
> @@ -20,6 +20,7 @@
>  #include <linux/input/touchscreen.h>
>  #include <linux/module.h>
>  #include <linux/of.h>
> +#include <linux/of_device.h>
>  
>  #define ICN8318_REG_POWER		4
>  #define ICN8318_REG_TOUCHDATA		16
> @@ -30,6 +31,14 @@
>  
>  #define ICN8318_MAX_TOUCHES		5
>  
> +#define ICN8505_REG_TOUCHDATA		0x1000
> +#define ICN8505_REG_CONFIGDATA		0x8000
> +
> +enum icn8318_model {
> +	ICN8318,
> +	ICN8505,
> +};
> +
>  struct icn8318_touch {
>  	__u8 slot;
>  	__be16 x;
> @@ -54,27 +63,37 @@ struct icn8318_data {
>  	struct input_dev *input;
>  	struct gpio_desc *wake_gpio;
>  	struct touchscreen_properties prop;
> +	enum icn8318_model model;
> +	int touchdata_reg;
>  };
>  
> -static int icn8318_read_touch_data(struct i2c_client *client,
> -				   struct icn8318_touch_data *touch_data)
> +static int icn8318_read_data(struct icn8318_data *data, int reg,
> +			     void *buf, int len)
>  {
> -	u8 reg = ICN8318_REG_TOUCHDATA;
> +	u8 addr[2];
>  	struct i2c_msg msg[2] = {
>  		{
> -			.addr = client->addr,
> -			.len = 1,
> -			.buf = &reg
> +			.addr = data->client->addr,
> +			.buf = addr
>  		},
>  		{
> -			.addr = client->addr,
> +			.addr = data->client->addr,
>  			.flags = I2C_M_RD,
> -			.len = sizeof(struct icn8318_touch_data),
> -			.buf = (u8 *)touch_data
> +			.len = len,
> +			.buf = buf
>  		}
>  	};
>  
> -	return i2c_transfer(client->adapter, msg, 2);
> +	if (data->model == ICN8318) {
> +		addr[0] = reg;
> +		msg[0].len = 1;
> +	} else {
> +		addr[0] = reg >> 8;
> +		addr[1] = reg & 0xff;
> +		msg[0].len = 2;
> +	}
> +
> +	return i2c_transfer(data->client->adapter, msg, 2);
>  }
>  
>  static inline bool icn8318_touch_active(u8 event)
> @@ -83,6 +102,14 @@ static inline bool icn8318_touch_active(u8 event)
>  	       (event == ICN8318_EVENT_UPDATE2);
>  }
>  
> +static u16 icn8318_coord_to_cpu(struct icn8318_data *data, __be16 coord)
> +{
> +	if (data->model == ICN8318)
> +		return be16_to_cpu(coord);
> +	else
> +		return le16_to_cpu((__force __le16)coord);

Hmm, this is quite ugly now. I'd drop the __be16 designations on
touch->x/y, made them u8 x[2], y[2], and used get_unaligned_le16() and
get_unaligned_be16() on them...

I also wonder if it would not be cleaner if instead of model constant
you used cost struct with pointers and other chip-specific data.

> +}
> +
>  static irqreturn_t icn8318_irq(int irq, void *dev_id)
>  {
>  	struct icn8318_data *data = dev_id;
> @@ -90,7 +117,8 @@ static irqreturn_t icn8318_irq(int irq, void *dev_id)
>  	struct icn8318_touch_data touch_data;
>  	int i, ret;
>  
> -	ret = icn8318_read_touch_data(data->client, &touch_data);
> +	ret = icn8318_read_data(data, data->touchdata_reg,
> +				&touch_data, sizeof(touch_data));
>  	if (ret < 0) {
>  		dev_err(dev, "Error reading touch data: %d\n", ret);
>  		return IRQ_HANDLED;
> @@ -122,8 +150,9 @@ static irqreturn_t icn8318_irq(int irq, void *dev_id)
>  			continue;
>  
>  		touchscreen_report_pos(data->input, &data->prop,
> -				       be16_to_cpu(touch->x),
> -				       be16_to_cpu(touch->y), true);
> +				       icn8318_coord_to_cpu(data, touch->x),
> +				       icn8318_coord_to_cpu(data, touch->y),
> +				       true);
>  	}
>  
>  	input_mt_sync_frame(data->input);
> @@ -187,6 +216,8 @@ static int icn8318_probe_of(struct icn8318_data *data, struct device *dev)
>  {
>  	int error;
>  
> +	data->model = (long)of_device_get_match_data(dev);
> +
>  	data->wake_gpio = devm_gpiod_get(dev, "wake", GPIOD_OUT_LOW);
>  	if (IS_ERR(data->wake_gpio)) {
>  		error = PTR_ERR(data->wake_gpio);
> @@ -210,6 +241,7 @@ static int icn8318_probe(struct i2c_client *client)
>  	struct icn8318_data *data;
>  	struct input_dev *input;
>  	int error;
> +	__le16 resolution[2];
>  
>  	if (!client->irq) {
>  		dev_err(dev, "Error no irq specified\n");
> @@ -240,6 +272,24 @@ static int icn8318_probe(struct i2c_client *client)
>  	if (error)
>  		return error;
>  
> +	if (data->model == ICN8318) {
> +		data->touchdata_reg = ICN8318_REG_TOUCHDATA;
> +	} else {
> +		data->touchdata_reg = ICN8505_REG_TOUCHDATA;
> +
> +		error = icn8318_read_data(data, ICN8505_REG_CONFIGDATA,
> +					  resolution, sizeof(resolution));
> +		if (error < 0) {
> +			dev_err(dev, "Error reading resolution: %d\n", error);
> +			return error;
> +		}
> +
> +		input_set_abs_params(input, ABS_MT_POSITION_X, 0,
> +				     le16_to_cpu(resolution[0]) - 1, 0, 0);
> +		input_set_abs_params(input, ABS_MT_POSITION_Y, 0,
> +				     le16_to_cpu(resolution[1]) - 1, 0, 0);
> +	}
> +
>  	touchscreen_parse_properties(input, true, &data->prop);
>  	if (!input_abs_get_max(input, ABS_MT_POSITION_X) ||
>  	    !input_abs_get_max(input, ABS_MT_POSITION_Y)) {
> @@ -274,7 +324,8 @@ static int icn8318_probe(struct i2c_client *client)
>  }
>  
>  static const struct of_device_id icn8318_of_match[] = {
> -	{ .compatible = "chipone,icn8318" },
> +	{ .compatible = "chipone,icn8318", .data = (void *)ICN8318 },
> +	{ .compatible = "chipone,icn8505", .data = (void *)ICN8505 },
>  	{ }
>  };
>  MODULE_DEVICE_TABLE(of, icn8318_of_match);
> -- 
> 2.13.0
> 

-- 
Dmitry