Re: [PATCH v2] input: PCAP2 based touchscreen driver

From: Dmitry Torokhov
Date: Mon Aug 03 2009 - 13:21:45 EST


Hi Daniel,

On Mon, Aug 03, 2009 at 11:30:00AM +0200, Daniel Ribeiro wrote:
> Touchscreen driver for the PCAP2 multi function device used in
> Motorola EZX smartphones.
>
> Signed-off-by: Daniel Ribeiro <drwyrm@xxxxxxxxx>
> Signed-off-by: Stefan Schmidt <stefan@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Antonio Ospite <ospite@xxxxxxxxxxxxxxxxx>
>
> ---
>
> Please note that the driver depends on some changes from the for-next branch
> in Samuel Ortiz's mfd tree:
> http://git.kernel.org/?p=linux/kernel/git/sameo/mfd-2.6.git;a=shortlog;h=for-next
>
> should this be queued by Samuel or the input people will you take care
> to send this mainline only after Samuel's tree has been merged?
>

I don't mind it going through another tree once all the kinks are worked
out.

> Changes from v1:
> * Added a warning in the default case in pcap_ts_read_xy()
> * Implemented input device .open() and .close() methods
> * Added a MODULE_ALIAS
> * Fixed Kconfig (To compile this driver as a module...)
> * Converted to dev_pm_ops
>
> v1 is in http://lkml.org/lkml/2009/6/27/109
>
>
> drivers/input/touchscreen/Kconfig | 9 ++
> drivers/input/touchscreen/Makefile | 1 +
> drivers/input/touchscreen/pcap_ts.c | 266 +++++++++++++++++++++++++++++++++++
> 3 files changed, 276 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/input/touchscreen/Kconfig b/drivers/input/touchscreen/Kconfig
> index 72e2712..7a69dbb 100644
> --- a/drivers/input/touchscreen/Kconfig
> +++ b/drivers/input/touchscreen/Kconfig
> @@ -498,4 +498,13 @@ config TOUCHSCREEN_W90X900
> To compile this driver as a module, choose M here: the
> module will be called w90p910_ts.
>
> +config TOUCHSCREEN_PCAP
> + tristate "Motorola PCAP touchscreen"
> + depends on EZX_PCAP
> + help
> + Say Y here if you have a Motorola EZX telephone and
> + want to enable support for the built-in touchscreen.
> +
> + To compile this driver as a module, choose M here: the
> + module will be called pcap_ts.
> endif
> diff --git a/drivers/input/touchscreen/Makefile b/drivers/input/touchscreen/Makefile
> index 3e1c5e0..4599bf7 100644
> --- a/drivers/input/touchscreen/Makefile
> +++ b/drivers/input/touchscreen/Makefile
> @@ -40,3 +40,4 @@ obj-$(CONFIG_TOUCHSCREEN_WM97XX_ATMEL) += atmel-wm97xx.o
> obj-$(CONFIG_TOUCHSCREEN_WM97XX_MAINSTONE) += mainstone-wm97xx.o
> obj-$(CONFIG_TOUCHSCREEN_WM97XX_ZYLONITE) += zylonite-wm97xx.o
> obj-$(CONFIG_TOUCHSCREEN_W90X900) += w90p910_ts.o
> +obj-$(CONFIG_TOUCHSCREEN_PCAP) += pcap_ts.o
> diff --git a/drivers/input/touchscreen/pcap_ts.c b/drivers/input/touchscreen/pcap_ts.c
> new file mode 100644
> index 0000000..86deefb
> --- /dev/null
> +++ b/drivers/input/touchscreen/pcap_ts.c
> @@ -0,0 +1,266 @@
> +/*
> + * Driver for Motorola PCAP2 touchscreen as found in the EZX phone platform.
> + *
> + * Copyright (C) 2006 Harald Welte <laforge@xxxxxxxxxxx>
> + * Copyright (C) 2009 Daniel Ribeiro <drwyrm@xxxxxxxxx>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/fs.h>
> +#include <linux/string.h>
> +#include <linux/pm.h>
> +#include <linux/timer.h>
> +#include <linux/interrupt.h>
> +#include <linux/platform_device.h>
> +#include <linux/input.h>
> +#include <linux/mfd/ezx-pcap.h>
> +
> +struct pcap_ts {
> + struct pcap_chip *pcap;
> + struct input_dev *input;
> + struct delayed_work work;
> + u16 x, y;
> + u16 pressure;
> + u8 read_state;
> +};
> +
> +#define SAMPLE_DELAY 20 /* msecs */
> +
> +#define X_AXIS_MIN 0
> +#define X_AXIS_MAX 1023
> +#define Y_AXIS_MAX X_AXIS_MAX
> +#define Y_AXIS_MIN X_AXIS_MIN
> +#define PRESSURE_MAX X_AXIS_MAX
> +#define PRESSURE_MIN X_AXIS_MIN
> +
> +static void pcap_ts_read_xy(void *data, u16 res[2])
> +{
> + struct pcap_ts *pcap_ts = data;
> +
> + switch (pcap_ts->read_state) {
> + case PCAP_ADC_TS_M_PRESSURE:
> + /* pressure reading is unreliable */
> + if (res[0] > PRESSURE_MIN && res[0] < PRESSURE_MAX)
> + pcap_ts->pressure = res[0];
> + pcap_ts->read_state = PCAP_ADC_TS_M_XY;
> + schedule_delayed_work(&pcap_ts->work, 0);
> + break;
> + case PCAP_ADC_TS_M_XY:
> + pcap_ts->y = res[0];
> + pcap_ts->x = res[1];
> + if (pcap_ts->x <= X_AXIS_MIN || pcap_ts->x >= X_AXIS_MAX ||
> + pcap_ts->y <= Y_AXIS_MIN || pcap_ts->y >= Y_AXIS_MAX) {
> + /* pen has been released */
> + input_report_abs(pcap_ts->input, ABS_PRESSURE, 0);
> + input_report_key(pcap_ts->input, BTN_TOUCH, 0);
> +
> + pcap_ts->read_state = PCAP_ADC_TS_M_STANDBY;
> + schedule_delayed_work(&pcap_ts->work, 0);
> + } else {
> + /* pen is touching the screen */
> + input_report_abs(pcap_ts->input, ABS_X, pcap_ts->x);
> + input_report_abs(pcap_ts->input, ABS_Y, pcap_ts->y);
> + input_report_key(pcap_ts->input, BTN_TOUCH, 1);
> + input_report_abs(pcap_ts->input, ABS_PRESSURE,
> + pcap_ts->pressure);
> +
> + /* switch back to pressure read mode */
> + pcap_ts->read_state = PCAP_ADC_TS_M_PRESSURE;
> + schedule_delayed_work(&pcap_ts->work,
> + msecs_to_jiffies(SAMPLE_DELAY));
> + }
> + input_sync(pcap_ts->input);
> + break;
> + default:
> + dev_warn(&pcap_ts->input->dev,
> + "pcap_ts: Warning, unhandled read_state %d\n",
> + pcap_ts->read_state);
> + break;
> + }
> +}
> +
> +static void pcap_ts_work(struct work_struct *work)
> +{
> + struct delayed_work *dw = container_of(work, struct delayed_work, work);
> + struct pcap_ts *pcap_ts = container_of(dw, struct pcap_ts, work);
> + u8 ch[2];
> +
> + pcap_set_ts_bits(pcap_ts->pcap,
> + pcap_ts->read_state << PCAP_ADC_TS_M_SHIFT);
> +
> + if (pcap_ts->read_state == PCAP_ADC_TS_M_STANDBY)
> + return;
> +
> + /* start adc conversion */
> + ch[0] = PCAP_ADC_CH_TS_X1;
> + ch[1] = PCAP_ADC_CH_TS_Y1;
> + pcap_adc_async(pcap_ts->pcap, PCAP_ADC_BANK_1, 0, ch,
> + pcap_ts_read_xy, pcap_ts);
> +}
> +
> +static irqreturn_t pcap_ts_event_touch(int pirq, void *data)
> +{
> + struct pcap_ts *pcap_ts = data;
> +
> + if (pcap_ts->read_state == PCAP_ADC_TS_M_STANDBY) {
> + pcap_ts->read_state = PCAP_ADC_TS_M_PRESSURE;
> + schedule_delayed_work(&pcap_ts->work, 0);
> + }
> + return IRQ_HANDLED;
> +}
> +
> +static int pcap_ts_open(struct input_dev *dev)
> +{
> + struct pcap_ts *pcap_ts = input_get_drvdata(dev);
> + int err;
> +
> + err = request_irq(pcap_to_irq(pcap_ts->pcap, PCAP_IRQ_TS),
> + pcap_ts_event_touch, 0, "Touch Screen", pcap_ts);
> + if (err)
> + return err;

Normally we try to request IRQ in probe() methods instead of delaying it
till open. Open() is supposed to kick-start the device, but not allocate
resoirces.

> +
> + pcap_ts->read_state = PCAP_ADC_TS_M_STANDBY;
> + schedule_delayed_work(&pcap_ts->work, 0);
> +
> + return 0;
> +}
> +
> +static void pcap_ts_close(struct input_dev *dev)
> +{
> + struct pcap_ts *pcap_ts = input_get_drvdata(dev);
> +
> + cancel_delayed_work_sync(&pcap_ts->work);

So what happens if the device raises IRQ here?

> + free_irq(pcap_to_irq(pcap_ts->pcap, PCAP_IRQ_TS), pcap_ts);
> +
> + pcap_ts->read_state = PCAP_ADC_TS_M_NONTS;
> + pcap_set_ts_bits(pcap_ts->pcap,
> + pcap_ts->read_state << PCAP_ADC_TS_M_SHIFT);
> +}
> +
> +static int __devinit pcap_ts_probe(struct platform_device *pdev)
> +{
> + struct input_dev *input_dev;
> + struct pcap_ts *pcap_ts;
> + int err = -ENOMEM;
> +
> + pcap_ts = kzalloc(sizeof(*pcap_ts), GFP_KERNEL);
> + if (!pcap_ts)
> + return err;
> +
> + pcap_ts->pcap = platform_get_drvdata(pdev);
> + platform_set_drvdata(pdev, pcap_ts);

Ewww... Don't mess with data that does not belong to you. Also I don't
see where you restore it so after unloading the driver reload with
probably lead to "inetersting" results.

> +
> + input_dev = input_allocate_device();
> + if (!input_dev)
> + goto fail;
> +
> + INIT_DELAYED_WORK(&pcap_ts->work, pcap_ts_work);
> +
> + pcap_ts->read_state = PCAP_ADC_TS_M_NONTS;
> + pcap_set_ts_bits(pcap_ts->pcap,
> + pcap_ts->read_state << PCAP_ADC_TS_M_SHIFT);
> +
> + pcap_ts->input = input_dev;
> + input_set_drvdata(input_dev, pcap_ts);
> +
> + input_dev->name = "pcap-touchscreen";
> + input_dev->phys = "pcap_ts/input0";
> + input_dev->id.bustype = BUS_HOST;
> + input_dev->id.vendor = 0x0001;
> + input_dev->id.product = 0x0002;
> + input_dev->id.version = 0x0100;
> + input_dev->dev.parent = &pdev->dev;
> + input_dev->open = pcap_ts_open;
> + input_dev->close = pcap_ts_close;
> +
> + input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
> + input_dev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
> + input_set_abs_params(input_dev, ABS_X, X_AXIS_MIN, X_AXIS_MAX, 0, 0);
> + input_set_abs_params(input_dev, ABS_Y, Y_AXIS_MIN, Y_AXIS_MAX, 0, 0);
> + input_set_abs_params(input_dev, ABS_PRESSURE, PRESSURE_MIN,
> + PRESSURE_MAX, 0, 0);
> +
> + err = input_register_device(pcap_ts->input);
> + if (err)
> + goto fail_allocate;
> +
> + return 0;
> +
> +fail_allocate:
> + input_free_device(input_dev);
> +fail:
> + kfree(pcap_ts);
> +
> + return err;
> +}
> +
> +static int __devexit pcap_ts_remove(struct platform_device *pdev)
> +{
> + struct pcap_ts *pcap_ts = platform_get_drvdata(pdev);
> +
> + input_unregister_device(pcap_ts->input);
> + kfree(pcap_ts);
> +
> + return 0;
> +}
> +
> +#ifdef CONFIG_PM
> +static int pcap_ts_suspend(struct device *dev)
> +{
> + struct pcap_ts *pcap_ts = dev_get_drvdata(dev);
> +
> + pcap_set_ts_bits(pcap_ts->pcap, PCAP_ADC_TS_REF_LOWPWR);
> + return 0;
> +}
> +
> +static int pcap_ts_resume(struct device *dev)
> +{
> + struct pcap_ts *pcap_ts = dev_get_drvdata(dev);
> +
> + pcap_set_ts_bits(pcap_ts->pcap,
> + pcap_ts->read_state << PCAP_ADC_TS_M_SHIFT);
> + return 0;
> +}
> +
> +static struct dev_pm_ops pcap_ts_pm_ops = {
> + .suspend = pcap_ts_suspend,
> + .resume = pcap_ts_resume,
> +};
> +#define PCAP_TS_PM_OPS (&pcap_ts_pm_ops)
> +#else
> +#define PCAP_TS_PM_OPS NULL
> +#endif
> +
> +static struct platform_driver pcap_ts_driver = {
> + .probe = pcap_ts_probe,
> + .remove = __devexit_p(pcap_ts_remove),
> + .driver = {
> + .name = "pcap-ts",
> + .owner = THIS_MODULE,
> + .pm = PCAP_TS_PM_OPS,
> + },
> +};
> +
> +static int __init pcap_ts_init(void)
> +{
> + return platform_driver_register(&pcap_ts_driver);
> +}
> +
> +static void __exit pcap_ts_exit(void)
> +{
> + platform_driver_unregister(&pcap_ts_driver);
> +}
> +
> +module_init(pcap_ts_init);
> +module_exit(pcap_ts_exit);
> +
> +MODULE_DESCRIPTION("Motorola PCAP2 touchscreen driver");
> +MODULE_AUTHOR("Daniel Ribeiro / Harald Welte");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:pcap_ts");
> --
> tg: (752a609..) ezx/pcap_ts (depends on: ezx/local/pcap)

--
Dmitry
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