Re: [PATCH] input:Adding support for Wacom Stylus with I2c interface

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

Hi Tatsunosuke,

On Tue, Oct 04, 2011 at 04:44:23PM +0900, Tatsunosuke Tobita wrote:
> From: Tatsunosuke Tobita <tobita.tatsunosuke@wacom.co.jp>
> 
> This driver has the same pen input process logic as wacom_w8001.c does.
> Also some modifications for structures were applied.
> 
> Signed-off-by: Tatsunosuke Tobita <tobita.tatsunosuke@wacom.co.jp>
> ---
>  drivers/input/touchscreen/wacom_i2c.c      |  216 ++++++++++++++++++++++++++++
>  drivers/input/touchscreen/wacom_i2c.h      |   66 +++++++++
>  drivers/input/touchscreen/wacom_i2c_func.c |   96 ++++++++++++
>  drivers/input/touchscreen/wacom_i2c_func.h |    8 +
>  4 files changed, 386 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/input/touchscreen/wacom_i2c.c
>  create mode 100644 drivers/input/touchscreen/wacom_i2c.h
>  create mode 100644 drivers/input/touchscreen/wacom_i2c_func.c
>  create mode 100644 drivers/input/touchscreen/wacom_i2c_func.h
> 
> diff --git a/drivers/input/touchscreen/wacom_i2c.c b/drivers/input/touchscreen/wacom_i2c.c
> new file mode 100644
> index 0000000..88a232b
> --- /dev/null
> +++ b/drivers/input/touchscreen/wacom_i2c.c
> @@ -0,0 +1,216 @@
> +/*
> + * Wacom Penabled Driver for I2C
> + *
> + * Copyright (c) 2011 Tatsunosuke Tobita, Wacom.
> + * <tobita.tatsunosuke@wacom.co.jp>
> + *
> + * 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 the Free Software
> + * Foundation; either version of 2 of the License,
> + * or (at your option) any later version.
> + *
> + * Note: Wacom Penabled Driver for I2C obtains data by polling.
> + * If you use irq, you must use the edge based rising
> + * interruption with low level pin.
> + */
> +
> +#include <linux/device.h>
> +#include "wacom_i2c_func.h"
> +
> +const unsigned short addr[2];
> +
> +static void wacom_i2c_workqueue(struct work_struct *workq)
> +{
> +	struct wacom_i2c *wac_i2c = container_of(workq, struct wacom_i2c, workq);
> +	wacom_set_coordination(wac_i2c);
> +}
> +
> +static enum hrtimer_restart wacom_i2c_timer(struct hrtimer *timer)
> +{
> +	struct wacom_i2c *wac_i2c = container_of(timer, struct wacom_i2c, timer);
> +
> +	queue_work(wacom_i2c_wq, &wac_i2c->workq);
> +	hrtimer_start(&wac_i2c->timer, ktime_set(0, POLL_RATE), HRTIMER_MODE_REL);
> +

So we have a timer and a workqueue. Why not use delayed_work?

> +	return HRTIMER_NORESTART;
> +}
> +
> +static int wacom_i2c_input_open(struct input_dev *dev)
> +{
> +	struct wacom_i2c *wac_i2c = input_get_drvdata(dev);
> +
> +	mutex_lock(&wac_i2c->lock);
> +	wac_i2c->dev->open = true;

Did you try actually compiling this?

> +	mutex_unlock(&wac_i2c->lock);
> +
> +	return 0;
> +}
> +
> +static void wacom_i2c_input_close(struct input_dev *dev)
> +{
> +	struct wacom_i2c *wac_i2c = input_get_drvdata(dev);
> +
> +	mutex_lock(&wac_i2c->lock);
> +	wac_i2c->dev->open = false;
> +	mutex_unlock(&wac_i2c->lock);
> +}
> +
> +static void wacom_i2c_set_input_values(struct i2c_client *client,
> +				       struct wacom_i2c *wac_i2c, struct input_dev *dev)
> +{
> +	dev->name = "WACOM_I2C_DIGITIZER";
> +	dev->id.bustype = BUS_I2C;
> +	dev->id.vendor = 0x56a;
> +	dev->dev.parent = &client->dev;
> +	dev->open = wacom_i2c_input_open;
> +	dev->close = wacom_i2c_input_close;
> +	dev->evbit[0] |= BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
> +
> +	__set_bit(ABS_X, dev->absbit);
> +	__set_bit(ABS_Y, dev->absbit);
> +	__set_bit(ABS_PRESSURE, dev->absbit);
> +	__set_bit(BTN_TOOL_PEN, dev->keybit);
> +	__set_bit(BTN_TOOL_RUBBER, dev->keybit);
> +	__set_bit(BTN_STYLUS, dev->keybit);
> +	__set_bit(BTN_STYLUS2, dev->keybit);
> +	__set_bit(BTN_TOUCH, dev->keybit);

Just put this into probe().

> +}
> +
> +static int wacom_i2c_probe(struct i2c_client *client,
> +			   const struct i2c_device_id *id)
> +{
> +	struct wacom_i2c *wac_i2c;
> +	int i, ret;
> +	i = ret = 0;
> +
> +	if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C))
> +		goto err2;
> +
> +	wac_i2c = kzalloc(sizeof(struct wacom_i2c), GFP_KERNEL);
> +	wac_i2c->wac_feature = wacom_feature_EMR;

Should we get this from i2c_device_id, platform data, device tree or
something else instead of hard-coding?

> +
> +	mutex_init(&wac_i2c->lock);
> +
> +	wac_i2c->dev = input_allocate_device();
> +	if (wac_i2c == NULL || wac_i2c->dev == NULL)
> +		goto fail;
> +	wacom_i2c_set_input_values(client, wac_i2c, wac_i2c->dev);
> +
> +	wac_i2c->client = client;
> +
> +	INIT_WORK(&wac_i2c->workq, wacom_i2c_workqueue);
> +
> +	ret = wacom_send_query(wac_i2c);
> +	if (ret < 0)
> +		goto err1;
> +
> +	wac_i2c->dev->id.version = wac_i2c->wac_feature.fw_version;
> +	input_set_abs_params(wac_i2c->dev, ABS_X, 0,
> +			     wac_i2c->wac_feature.x_max, 0, 0);
> +	input_set_abs_params(wac_i2c->dev, ABS_Y, 0,
> +			     wac_i2c->wac_feature.y_max, 0, 0);
> +	input_set_abs_params(wac_i2c->dev, ABS_PRESSURE, 0,
> +			     wac_i2c->wac_feature.pressure_max, 0, 0);
> +	input_set_drvdata(wac_i2c->dev, wac_i2c);
> +
> +	i2c_set_clientdata(client, wac_i2c);
> +	if (input_register_device(wac_i2c->dev))
> +		goto err1;

You should report error returned by input_register_device().

> +
> +	hrtimer_init(&wac_i2c->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
> +	wac_i2c->timer.function = wacom_i2c_timer;
> +	hrtimer_start(&wac_i2c->timer, ktime_set(1, 0), HRTIMER_MODE_REL);

Why start timer if nobody has the device opened yet?

> +	printk(KERN_INFO "WACOM_I2C_DIGITIZER: initialized and started \n");
> +
> +	return 0;
> +
> + err2:
> +	printk(KERN_ERR "wacom_i2c:No I2C functionality found\n");
> +	return -ENODEV;
> +
> + err1:
> +	printk(KERN_ERR "wacom_i2c:err1 occured(num:%d)\n", ret);
> +	input_free_device(wac_i2c->dev);
> +	wac_i2c->dev = NULL;
> +	return -EIO;
> +
> + fail:
> +	printk(KERN_ERR "wacom_i2c:fail occured\n");
> +	return -ENOMEM;
> +}
> +
> +static int wacom_i2c_remove(struct i2c_client *client)
> +{
> +	struct wacom_i2c *wac_i2c = i2c_get_clientdata(client);
> +
> +	input_unregister_device(wac_i2c->dev);

Timer fires here -> *BOOM*. You should cancel the timer in close().

Also, polling-only mode is hardly useful for a touchscreen driver. Is
there a chance you could switch to interrupt-driven mode instead?

> +	hrtimer_cancel(&wac_i2c->timer);
> +	kfree(wac_i2c);
> +
> +	return 0;
> +}
> +
> +static int wacom_i2c_suspend(struct i2c_client *client, pm_message_t mesg)
> +{
> +	int ret;
> +	struct wacom_i2c *wac_i2c = i2c_get_clientdata(client);
> +
> +	hrtimer_cancel(&wac_i2c->timer);
> +	cancel_work_sync(&wac_i2c->workq);
> +	ret = wac_i2c->power(0);
> +
> +	return 0;
> +}
> +
> +static int wacom_i2c_resume(struct i2c_client *client)
> +{
> +	struct wacom_i2c *wac_i2c = i2c_get_clientdata(client);
> +
> +	hrtimer_start(&wac_i2c->timer, ktime_set(1, 0), HRTIMER_MODE_REL);
> +
> +	return 0;
> +}
> +
> +static const struct i2c_device_id wacom_i2c_id[] = {
> +	{WACNAME, 0},
> +	{},
> +};
> +MODULE_DEVICE_TABLE(i2c, wacom_i2c_id);
> +
> +static struct i2c_driver wacom_i2c_driver = {
> +	.driver = {
> +		.name = "wacom_i2c",
> +	},
> +
> +	.probe = wacom_i2c_probe,
> +	.remove = wacom_i2c_remove,
> +	.suspend = wacom_i2c_suspend,
> +	.resume = wacom_i2c_resume,

Please use dev_pm_ops.

> +	.id_table = wacom_i2c_id,
> +};
> +
> +static int __init wacom_i2c_init()
> +{
> +
> +	wacom_i2c_wq = create_singlethread_workqueue("wacom_i2c_wq");
> +	if (!wacom_i2c_wq)
> +		return -ENOMEM;

There is no reason for dedicated workqueue in mainline.

> +
> +	return i2c_add_driver(&wacom_i2c_driver);
> +}
> +
> +static void __exit wacom_i2c_exit()
> +{
> +	if (wacom_i2c_wq)

The test is useless.

> +		destroy_workqueue(wacom_i2c_wq);
> +
> +	i2c_del_driver(&wacom_i2c_driver);
> +}
> +
> +module_init(wacom_i2c_init);
> +module_exit(wacom_i2c_exit);
> +
> +MODULE_AUTHOR("Tatsunosuke Tobita <tobita.tatsunosuke@wacom.co.jp>");
> +MODULE_DESCRIPTION("WACOM EMR I2C Driver");
> +MODULE_LICENSE("GPL");
> diff --git a/drivers/input/touchscreen/wacom_i2c.h b/drivers/input/touchscreen/wacom_i2c.h
> new file mode 100644
> index 0000000..390b765
> --- /dev/null
> +++ b/drivers/input/touchscreen/wacom_i2c.h
> @@ -0,0 +1,66 @@
> +#ifndef WACOM_I2C_H
> +#define WAOCM_I2C_H
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/kernel.h>
> +#include <linux/input.h>
> +#include <linux/i2c.h>
> +#include <linux/slab.h>
> +#include <linux/hrtimer.h>
> +#include <linux/delay.h>
> +#include <linux/uaccess.h>
> +#include <asm/unaligned.h>
> +
> +#define NAMEBUF 12
> +#define WACNAME "WAC_I2C_EMR"
> +
> +/*Wacom Command*/
> +#define COM_COORD_NUM      256
> +#define COM_SAMPLERATE_40  0x33
> +#define COM_SAMPLERATE_80  0x32
> +#define COM_SAMPLERATE_133 0x31
> +#define CMD_QUERY0         0x04
> +#define CMD_QUERY1         0x00
> +#define CMD_QUERY2         0x33
> +#define CMD_QUERY3         0x02
> +#define CMD_THROW0         0x05
> +#define CMD_THROW1         0x00
> +#define QUERY_SIZE           19
> +
> +/*I2C address for digitizer*/
> +#define WACOM_I2C_ADDR   0x09
> +
> +/*Polling Rate*/
> +#define POLL_RATE 7500000
> +
> +static struct workqueue_struct *wacom_i2c_wq;

There shouldn't be static variables in header files.

> +
> +/*Parameters for wacom own features*/
> +struct wacom_features {
> +	int x_max;
> +	int y_max;
> +	int pressure_max;
> +	char fw_version;
> +};
> +
> +static struct wacom_features wacom_feature_EMR = {
> +	16128,
> +	8448,
> +	256,
> +	0x10,
> +};
> +
> +/*Parameters for i2c driver*/
> +struct wacom_i2c {
> +	struct i2c_client *client;
> +	struct input_dev *dev;
> +	struct mutex lock;
> +	struct work_struct workq;
> +	struct hrtimer timer;
> +	struct wacom_features wac_feature;
> +	int (*power)(int on);
> +	int type;
> +	const char name[NAMEBUF];
> +};
> +#endif
> diff --git a/drivers/input/touchscreen/wacom_i2c_func.c b/drivers/input/touchscreen/wacom_i2c_func.c
> new file mode 100644
> index 0000000..97f086c
> --- /dev/null
> +++ b/drivers/input/touchscreen/wacom_i2c_func.c
> @@ -0,0 +1,96 @@
> +#include "wacom_i2c_func.h"
> +

Why is is split? Also, what license does this code have?

> +int wacom_send_query(struct wacom_i2c *wac_i2c)
> +{
> +	int ret;
> +	u8 cmd[4] = {CMD_QUERY0, CMD_QUERY1, CMD_QUERY2, CMD_QUERY3};
> +	u8 data[COM_COORD_NUM];
> +
> +	ret = i2c_master_send(wac_i2c->client, cmd, sizeof(cmd));
> +	if (ret < 0) {
> +		printk(KERN_ERR "wacom_i2c: Sending Query failed \n");
> +		return -1;
> +	}
> +
> +	cmd[0] = CMD_THROW0; cmd[1] = CMD_THROW1;
> +	ret = i2c_master_send(wac_i2c->client, cmd, 2);
> +	if (ret < 0) {
> +		printk(KERN_ERR "wacom_i2c: Sending Query failed \n");
> +		return -1;
> +	}
> +
> +	ret = i2c_master_recv(wac_i2c->client, data, QUERY_SIZE);
> +	if (ret < 0) {
> +		printk(KERN_ERR "wacom_i2c: Receiving Query failed\n");
> +		return -1;
> +	}
> +
> +	wac_i2c->wac_feature.x_max = get_unaligned_le16(&data[3]);
> +	wac_i2c->wac_feature.y_max = get_unaligned_le16(&data[5]);
> +	wac_i2c->wac_feature.pressure_max = get_unaligned_le16(&data[11]);
> +	wac_i2c->wac_feature.fw_version = get_unaligned_le16(&data[13]);
> +
> +	printk(KERN_INFO "wacom_i2c: x_max:%d, y_max:%d, pressure:%d, fw:%d\n",
> +	       wac_i2c->wac_feature.x_max, wac_i2c->wac_feature.y_max,
> +	       wac_i2c->wac_feature.pressure_max, wac_i2c->wac_feature.fw_version);
> +

Please use dev_xxx() for reporting.

> +	return 0;
> +}
> +
> +int wacom_set_coordination(struct wacom_i2c *wac_i2c)
> +{
> +	int ret = 0;
> +	unsigned int x, y, pressure;
> +	unsigned char rdy, tsw, f1, f2, ers;
> +	u8 data[COM_COORD_NUM];
> +
> +	ret = i2c_master_recv(wac_i2c->client, data, QUERY_SIZE);
> +	if (ret >= 0) {
> +		tsw = data[3]&0x01;
> +		ers = data[3]&0x04;
> +		f1 = data[3]&0x02;
> +		f2 = data[3]&0x10;
> +		rdy = data[3]&0x20;
> +		x = le16_to_cpup((__le16 *)&data[4]);
> +		y = le16_to_cpup((__le16 *)&data[6]);
> +		pressure = le16_to_cpup((__le16 *)&data[8]);
> +
> +		switch (wac_i2c->type) {
> +		case BTN_TOOL_RUBBER:
> +			if (!f2) {
> +				input_report_abs(wac_i2c->dev, ABS_PRESSURE, 0);
> +				input_report_key(wac_i2c->dev, BTN_TOUCH, 0);
> +				input_report_key(wac_i2c->dev, BTN_STYLUS, 0);
> +				input_report_key(wac_i2c->dev, BTN_STYLUS2, 0);
> +				input_report_key(wac_i2c->dev, BTN_TOOL_RUBBER, 0);
> +				input_sync(wac_i2c->dev);
> +				wac_i2c->type = BTN_TOOL_PEN;
> +			}
> +			break;
> +
> +		case KEY_RESERVED:
> +			wac_i2c->type = f2 ? BTN_TOOL_RUBBER : BTN_TOOL_PEN;
> +			break;
> +
> +		default:
> +			input_report_key(wac_i2c->dev, BTN_STYLUS2, f2);
> +			break;
> +		}
> +
> +		input_report_abs(wac_i2c->dev, ABS_X, x);
> +		input_report_abs(wac_i2c->dev, ABS_Y, y);
> +		input_report_abs(wac_i2c->dev, ABS_PRESSURE, pressure);
> +		input_report_key(wac_i2c->dev, BTN_TOUCH, (tsw || ers));
> +		input_report_key(wac_i2c->dev, BTN_STYLUS, f1);
> +
> +		input_sync(wac_i2c->dev);
> +
> +		if (!rdy)
> +			wac_i2c->type = KEY_RESERVED;
> +
> +	} else {
> +		return -1;
> +	}
> +
> +	return 0;
> +}
> diff --git a/drivers/input/touchscreen/wacom_i2c_func.h b/drivers/input/touchscreen/wacom_i2c_func.h
> new file mode 100644
> index 0000000..cce35c4
> --- /dev/null
> +++ b/drivers/input/touchscreen/wacom_i2c_func.h
> @@ -0,0 +1,8 @@
> +#ifndef WACOM_I2C_FUNC_H
> +#define WACOM_I2C_FUNC_H
> +
> +#include "wacom_i2c.h"
> +
> +int wacom_set_coordination(struct wacom_i2c *wac_i2c);
> +int wacom_send_query(struct wacom_i2c *wac_i2c);
> +#endif

Thanks.

-- 
Dmitry