Message-Id: <20090812024609.5EB8B526EC9@mailhub.coreip.homeip.net>
Date:	Tue, 11 Aug 2009 19:15:33 -0700
From:	Dmitry Torokhov <dmitry.torokhov@...il.com>
To:	Sascha Hauer <s.hauer@...gutronix.de>
Cc:	linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.arm.linux.org.uk,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	linux-input@...r.kernel.org
Subject: Re: [PATCH 2/5] [input] add mc13783 touchscreen driver

Hi Sascha,

On Tue, Aug 11, 2009 at 11:07:44AM +0200, Sascha Hauer wrote:
> This driver provides support for the touchscreen interface
> integrated into the Freescale MC13783.
> 
> Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
> Cc: Dmitry Torokhov <dmitry.torokhov@...il.com>
> Cc: Mark Brown <broonie@...nsource.wolfsonmicro.com>
> Cc: linux-input@...r.kernel.org
> ---
>  drivers/input/touchscreen/Kconfig      |   12 ++
>  drivers/input/touchscreen/Makefile     |    1 +
>  drivers/input/touchscreen/mc13783_ts.c |  228 ++++++++++++++++++++++++++++++++
>  3 files changed, 241 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/input/touchscreen/mc13783_ts.c
> 
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 72e2712..7451cf0 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -413,6 +413,18 @@ config TOUCHSCREEN_USB_COMPOSITE
>  	  To compile this driver as a module, choose M here: the
>  	  module will be called usbtouchscreen.
>  
> +config TOUCHSCREEN_MC13783
> +	tristate "Freescale MC13783 touchscreen input driver"
> +	depends on MFD_MC13783
> +	help
> +	  Say Y here if you have an Freescale MC13783 PMIC on your
> +	  board and want to use its touchscreen
> +
> +	  If unsure, say N.
> +
> +	  To compile this driver as a module, choose M here: the
> +	  module will be called mxc_ts.
> +
>  config TOUCHSCREEN_USB_EGALAX
>  	default y
>  	bool "eGalax, eTurboTouch CT-410/510/700 device support" if EMBEDDED
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 3e1c5e0..7b79598 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -20,6 +20,7 @@ obj-$(CONFIG_TOUCHSCREEN_INEXIO)	+= inexio.o
>  obj-$(CONFIG_TOUCHSCREEN_MIGOR)		+= migor_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_MTOUCH)	+= mtouch.o
>  obj-$(CONFIG_TOUCHSCREEN_MK712)		+= mk712.o
> +obj-$(CONFIG_TOUCHSCREEN_MC13783)	+= mc13783_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_HP600)		+= hp680_ts_input.o
>  obj-$(CONFIG_TOUCHSCREEN_HP7XX)		+= jornada720_ts.o
>  obj-$(CONFIG_TOUCHSCREEN_HTCPEN)	+= htcpen.o
> diff --git a/drivers/input/touchscreen/mc13783_ts.c b/drivers/input/touchscreen/mc13783_ts.c
> new file mode 100644
> index 0000000..9dfe280
> --- /dev/null
> +++ b/drivers/input/touchscreen/mc13783_ts.c
> @@ -0,0 +1,228 @@
> +/*
> + * Driver for the Freescale Semiconductor MC13783 touchscreen.
> + *
> + * Copyright 2004-2007 Freescale Semiconductor, Inc. All Rights Reserved.
> + * Copyright (C) 2009 Sascha Hauer, Pengutronix
> + *
> + * Initial development of this code was funded by
> + * Phytec Messtechnik GmbH, http://www.phytec.de
> + *
> + * 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 2
> + * of the License, or (at your option) any later version.
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program; if not, write to the Free Software Foundation, Inc., 51
> + * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
> + *
> + */
> +
> +#include <linux/mfd/mc13783-private.h>
> +#include <linux/platform_device.h>
> +#include <linux/mfd/mc13783.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/delay.h>
> +#include <linux/input.h>
> +#include <linux/sched.h>
> +#include <linux/init.h>
> +
> +#define MC13783_TS_NAME	"mc13783-ts"
> +
> +struct mc13783_ts_priv {
> +	struct input_dev *idev;
> +	struct mc13783 *mc13783;
> +	struct delayed_work work;
> +	struct workqueue_struct *workq;
> +	unsigned int sample[4];
> +};
> +
> +static inline void mc13783_ts_start_conversion(struct mc13783_ts_priv *priv)
> +{
> +	unsigned int reg_adc0, reg_adc1;
> +
> +	reg_adc0 = MC13783_ADC0_ADREFEN | MC13783_ADC0_ADREFMODE
> +			| MC13783_ADC0_TSMOD0 | MC13783_ADC0_TSMOD1
> +			| MC13783_ADC0_ADINC1 | MC13783_ADC0_ADINC2;
> +	reg_adc1 = MC13783_ADC1_ADEN | MC13783_ADC1_ADSEL | MC13783_ADC1_ADA22
> +			| MC13783_ADC1_ASC | MC13783_ADC1_ADTRIGIGN;
> +
> +	mc13783_reg_write(priv->mc13783, MC13783_REG_ADC_0, reg_adc0);
> +	mc13783_reg_write(priv->mc13783, MC13783_REG_ADC_1, reg_adc1);
> +}

I do not see this function used...

> +
> +static inline void mc13783_ts_set_irq_mode(struct mc13783_ts_priv *priv)
> +{
> +	unsigned int reg_adc0, reg_adc1;
> +
> +	reg_adc0 = MC13783_ADC0_ADREFEN | MC13783_ADC0_ADREFMODE
> +			| MC13783_ADC0_TSMOD0;
> +	reg_adc1 = MC13783_ADC1_ADEN | MC13783_ADC1_ADTRIGIGN;
> +
> +	mc13783_reg_write(priv->mc13783, MC13783_REG_ADC_0, reg_adc0);
> +	mc13783_reg_write(priv->mc13783, MC13783_REG_ADC_1, reg_adc1);
> +}

Nor this one...

> +
> +#define TS_MIN 1
> +#define TS_MAX 1000
> +
> +static void mc13783_ts_handler(int irq, void *data)
> +{
> +	struct mc13783_ts_priv *priv = data;
> +	unsigned int sts;
> +
> +	mc13783_reg_read(priv->mc13783, MC13783_REG_INTERRUPT_STATUS_0, &sts);
> +	mc13783_reg_write(priv->mc13783, MC13783_REG_INTERRUPT_STATUS_0,
> +			sts & MC13783_INT_STAT_TSI);
> +
> +	if (sts & MC13783_INT_STAT_TSI)
> +		queue_work(priv->workq, &priv->work.work);

Do not expose the innards of delayed_work, simply do:

	queue_delayed_work(priv->workq, &priv->work, 0);

> +}
> +
> +static void mc13783_ts_report_sample(struct mc13783_ts_priv *priv)
> +{
> +	int x, y, press = 0;
> +
> +	x = (priv->sample[2] >> 2) & 0x3ff;
> +	y = (priv->sample[3] >> 2) & 0x3ff;
> +
> +	pr_debug("mc13783_ts: x: %d y: %d\n", x, y);
> +
> +	if (x > TS_MIN && x < TS_MAX && y > TS_MIN && y < TS_MAX) {
> +		press = 1;
> +		input_report_abs(priv->idev, ABS_X, x);
> +		input_report_abs(priv->idev, ABS_Y, y);
> +
> +		queue_delayed_work(priv->workq, &priv->work, HZ / 50);
> +	}
> +
> +	input_report_abs(priv->idev, ABS_PRESSURE, press);

This device does not appear to privide pressure readings, use BTN_TOUCH
alone to indicate touches instead of fake ABS_PRESSURE event. Yes, I
know that older versions of tslib only recognize ABS_PRESSURE...

> +	input_sync(priv->idev);
> +}
> +
> +static void mc13783_ts_work(struct work_struct *work)
> +{
> +	struct mc13783_ts_priv *priv =
> +		container_of(work, struct mc13783_ts_priv, work.work);
> +	unsigned int mode = MC13783_ADC_MODE_TS;
> +	unsigned int channel = 12;
> +	int ret;
> +
> +	ret = mc13783_adc_do_conversion
> +		(priv->mc13783, mode, channel, priv->sample);
> +
> +	if (!ret)
> +		mc13783_ts_report_sample(priv);
> +}
> +
> +static int __init mc13783_ts_probe(struct platform_device *pdev)

No __inits on probe() methods, they are normally __devinit.

> +{
> +	struct mc13783_ts_priv *priv;
> +	struct input_dev *idev;
> +	int ret;
> +
> +	priv = kzalloc(sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	priv->mc13783 = pdev->dev.platform_data;
> +
> +	idev = input_allocate_device();
> +	if (!idev) {
> +		ret = -ENOMEM;
> +		goto err_input_alloc;
> +	}
> +
> +	priv->idev = idev;
> +	idev->name = MC13783_TS_NAME;
> +	idev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
> +	idev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
> +	idev->absbit[0] = BIT_MASK(ABS_X) | BIT_MASK(ABS_Y) |
> +					BIT_MASK(ABS_PRESSURE);
> +

It is usually a good idea to indicate the range of reported values with
input_set_abs_params().

> +	platform_set_drvdata(pdev, priv);
> +
> +	ret = mc13783_register_irq(priv->mc13783, MC13783_IRQ_TS,
> +		mc13783_ts_handler, priv);
> +	if (ret)
> +		goto err_failed_irq;
> +
> +	ret = input_register_device(priv->idev);
> +	if (ret) {
> +		dev_err(&pdev->dev,
> +				"register input device failed with %d\n", ret);
> +		goto err_failed_register;
> +	}
> +
> +	/* unmask the ts wakeup interrupt */
> +	mc13783_set_bits(priv->mc13783, MC13783_REG_INTERRUPT_MASK_0,
> +			MC13783_INT_MASK_TSM, 0);
> +
> +	mc13783_adc_set_ts_status(priv->mc13783, 1);
> +
> +	INIT_DELAYED_WORK(&priv->work, mc13783_ts_work);
> +
> +	priv->workq = create_singlethread_workqueue("mc13783_ts");

Do you really need a separate workqueue? Would not keventd suffice?

> +	queue_delayed_work(priv->workq, &priv->work, HZ / 20);

Starting of the contoller is better done in input_dev->open() method when
there are uses as opposed to probe() method.

> +
> +	return 0;
> +
> +err_failed_register:
> +	mc13783_free_irq(priv->mc13783, MC13783_IRQ_TS);
> +err_failed_irq:
> +	input_free_device(priv->idev);
> +err_input_alloc:
> +	kfree(priv);
> +
> +	return ret;
> +}
> +
> +static int __devexit mc13783_ts_remove(struct platform_device *pdev)
> +{
> +	struct mc13783_ts_priv *priv = platform_get_drvdata(pdev);
> +
> +	mc13783_adc_set_ts_status(priv->mc13783, 0);
> +
> +	mc13783_free_irq(priv->mc13783, MC13783_IRQ_TS);
> +
> +	cancel_delayed_work(&priv->work);
> +	destroy_workqueue(priv->workq);
> +
> +	input_unregister_device(priv->idev);
> +	input_free_device(priv->idev);

input_free_device() is verboten after unregister.

> +
> +	kfree(priv);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver mc13783_ts_driver = {
> +	.probe		= mc13783_ts_probe,
> +	.remove 	= __devexit_p(mc13783_ts_remove),

Whitespace damage.

> +	.driver		= {
> +		.owner	= THIS_MODULE,
> +		.name	= MC13783_TS_NAME,
> +	},
> +};
> +
> +static int __init mc13783_ts_init(void)
> +{
> +	return platform_driver_register(&mc13783_ts_driver);
> +}
> +
> +static void __exit mc13783_ts_exit(void)
> +{
> +	platform_driver_unregister(&mc13783_ts_driver);
> +}
> +
> +module_init(mc13783_ts_init);
> +module_exit(mc13783_ts_exit);
> +
> +MODULE_DESCRIPTION("MC13783 input touchscreen driver");
> +MODULE_AUTHOR("Sascha Hauer, <s.hauer@...gutronix.de>");
> +MODULE_LICENSE("GPL");

MODULE_ALIAS()?

-- 
Dmitry
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