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linux/drivers/mfd/ucb1x00-ts.c
Russell King 0af5e4c36e MFD: ucb1x00-ts: fix resume failure 
If the ucb1x00 touchscreen is resumed while the touchscreen is being
touched, the main thread stops responding.  This occurs because two
things happen:

1. When we suspended, we were woken up, and executed the loop.
   Finding that the touchscreen was not pressed, we prepare to
   schedule for a maximum timeout, before being stopped in
   try_to_freeze().

2. an irq occurs, we disable the irq, and mark it as disabled,
   and wake the thread.  This wake occurs while the thread is
   still within __refrigerator()

3. The thread is unfrozen, and __refrigerator() sets the threads
   state back to INTERRUPTIBLE.

We then drop into schedule_timeout() with an infinite timeout and the
IRQ disabled.  This prevents any further screen touches activating
the thread.

Fix this by using kthread_freezable_should_stop() which handles the
freezing issues for us outside of the hotspot where the task state
matters.  Include a flag to ignore the touchscreen until it is
released to avoid sending unintended data to the application.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2012-01-22 21:10:40 +00:00

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/*
* Touchscreen driver for UCB1x00-based touchscreens
*
* Copyright (C) 2001 Russell King, All Rights Reserved.
* Copyright (C) 2005 Pavel Machek
*
* 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.
*
* 21-Jan-2002 <jco@ict.es> :
*
* Added support for synchronous A/D mode. This mode is useful to
* avoid noise induced in the touchpanel by the LCD, provided that
* the UCB1x00 has a valid LCD sync signal routed to its ADCSYNC pin.
* It is important to note that the signal connected to the ADCSYNC
* pin should provide pulses even when the LCD is blanked, otherwise
* a pen touch needed to unblank the LCD will never be read.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/smp.h>
#include <linux/sched.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/string.h>
#include <linux/input.h>
#include <linux/device.h>
#include <linux/freezer.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/mfd/ucb1x00.h>
#include <mach/dma.h>
#include <mach/collie.h>
#include <asm/mach-types.h>
struct ucb1x00_ts {
struct input_dev *idev;
struct ucb1x00 *ucb;
wait_queue_head_t irq_wait;
struct task_struct *rtask;
u16 x_res;
u16 y_res;
unsigned int adcsync:1;
};
static int adcsync;
static inline void ucb1x00_ts_evt_add(struct ucb1x00_ts *ts, u16 pressure, u16 x, u16 y)
{
struct input_dev *idev = ts->idev;
input_report_abs(idev, ABS_X, x);
input_report_abs(idev, ABS_Y, y);
input_report_abs(idev, ABS_PRESSURE, pressure);
input_report_key(idev, BTN_TOUCH, 1);
input_sync(idev);
}
static inline void ucb1x00_ts_event_release(struct ucb1x00_ts *ts)
{
struct input_dev *idev = ts->idev;
input_report_abs(idev, ABS_PRESSURE, 0);
input_report_key(idev, BTN_TOUCH, 0);
input_sync(idev);
}
/*
* Switch to interrupt mode.
*/
static inline void ucb1x00_ts_mode_int(struct ucb1x00_ts *ts)
{
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMX_POW | UCB_TS_CR_TSPX_POW |
UCB_TS_CR_TSMY_GND | UCB_TS_CR_TSPY_GND |
UCB_TS_CR_MODE_INT);
}
/*
* Switch to pressure mode, and read pressure. We don't need to wait
* here, since both plates are being driven.
*/
static inline unsigned int ucb1x00_ts_read_pressure(struct ucb1x00_ts *ts)
{
if (machine_is_collie()) {
ucb1x00_io_write(ts->ucb, COLLIE_TC35143_GPIO_TBL_CHK, 0);
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSPX_POW | UCB_TS_CR_TSMX_POW |
UCB_TS_CR_MODE_POS | UCB_TS_CR_BIAS_ENA);
udelay(55);
return ucb1x00_adc_read(ts->ucb, UCB_ADC_INP_AD2, ts->adcsync);
} else {
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMX_POW | UCB_TS_CR_TSPX_POW |
UCB_TS_CR_TSMY_GND | UCB_TS_CR_TSPY_GND |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
return ucb1x00_adc_read(ts->ucb, UCB_ADC_INP_TSPY, ts->adcsync);
}
}
/*
* Switch to X position mode and measure Y plate. We switch the plate
* configuration in pressure mode, then switch to position mode. This
* gives a faster response time. Even so, we need to wait about 55us
* for things to stabilise.
*/
static inline unsigned int ucb1x00_ts_read_xpos(struct ucb1x00_ts *ts)
{
if (machine_is_collie())
ucb1x00_io_write(ts->ucb, 0, COLLIE_TC35143_GPIO_TBL_CHK);
else {
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMX_GND | UCB_TS_CR_TSPX_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMX_GND | UCB_TS_CR_TSPX_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
}
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMX_GND | UCB_TS_CR_TSPX_POW |
UCB_TS_CR_MODE_POS | UCB_TS_CR_BIAS_ENA);
udelay(55);
return ucb1x00_adc_read(ts->ucb, UCB_ADC_INP_TSPY, ts->adcsync);
}
/*
* Switch to Y position mode and measure X plate. We switch the plate
* configuration in pressure mode, then switch to position mode. This
* gives a faster response time. Even so, we need to wait about 55us
* for things to stabilise.
*/
static inline unsigned int ucb1x00_ts_read_ypos(struct ucb1x00_ts *ts)
{
if (machine_is_collie())
ucb1x00_io_write(ts->ucb, 0, COLLIE_TC35143_GPIO_TBL_CHK);
else {
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMY_GND | UCB_TS_CR_TSPY_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMY_GND | UCB_TS_CR_TSPY_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
}
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMY_GND | UCB_TS_CR_TSPY_POW |
UCB_TS_CR_MODE_POS | UCB_TS_CR_BIAS_ENA);
udelay(55);
return ucb1x00_adc_read(ts->ucb, UCB_ADC_INP_TSPX, ts->adcsync);
}
/*
* Switch to X plate resistance mode. Set MX to ground, PX to
* supply. Measure current.
*/
static inline unsigned int ucb1x00_ts_read_xres(struct ucb1x00_ts *ts)
{
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMX_GND | UCB_TS_CR_TSPX_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
return ucb1x00_adc_read(ts->ucb, 0, ts->adcsync);
}
/*
* Switch to Y plate resistance mode. Set MY to ground, PY to
* supply. Measure current.
*/
static inline unsigned int ucb1x00_ts_read_yres(struct ucb1x00_ts *ts)
{
ucb1x00_reg_write(ts->ucb, UCB_TS_CR,
UCB_TS_CR_TSMY_GND | UCB_TS_CR_TSPY_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
return ucb1x00_adc_read(ts->ucb, 0, ts->adcsync);
}
static inline int ucb1x00_ts_pen_down(struct ucb1x00_ts *ts)
{
unsigned int val = ucb1x00_reg_read(ts->ucb, UCB_TS_CR);
if (machine_is_collie())
return (!(val & (UCB_TS_CR_TSPX_LOW)));
else
return (val & (UCB_TS_CR_TSPX_LOW | UCB_TS_CR_TSMX_LOW));
}
/*
* This is a RT kernel thread that handles the ADC accesses
* (mainly so we can use semaphores in the UCB1200 core code
* to serialise accesses to the ADC).
*/
static int ucb1x00_thread(void *_ts)
{
struct ucb1x00_ts *ts = _ts;
DECLARE_WAITQUEUE(wait, current);
bool frozen, ignore = false;
int valid = 0;
set_freezable();
add_wait_queue(&ts->irq_wait, &wait);
while (!kthread_freezable_should_stop(&frozen)) {
unsigned int x, y, p;
signed long timeout;
if (frozen)
ignore = true;
ucb1x00_adc_enable(ts->ucb);
x = ucb1x00_ts_read_xpos(ts);
y = ucb1x00_ts_read_ypos(ts);
p = ucb1x00_ts_read_pressure(ts);
/*
* Switch back to interrupt mode.
*/
ucb1x00_ts_mode_int(ts);
ucb1x00_adc_disable(ts->ucb);
msleep(10);
ucb1x00_enable(ts->ucb);
if (ucb1x00_ts_pen_down(ts)) {
set_current_state(TASK_INTERRUPTIBLE);
ucb1x00_enable_irq(ts->ucb, UCB_IRQ_TSPX, machine_is_collie() ? UCB_RISING : UCB_FALLING);
ucb1x00_disable(ts->ucb);
/*
* If we spat out a valid sample set last time,
* spit out a "pen off" sample here.
*/
if (valid) {
ucb1x00_ts_event_release(ts);
valid = 0;
}
timeout = MAX_SCHEDULE_TIMEOUT;
} else {
ucb1x00_disable(ts->ucb);
/*
* Filtering is policy. Policy belongs in user
* space. We therefore leave it to user space
* to do any filtering they please.
*/
if (!ignore) {
ucb1x00_ts_evt_add(ts, p, x, y);
valid = 1;
}
set_current_state(TASK_INTERRUPTIBLE);
timeout = HZ / 100;
}
schedule_timeout(timeout);
}
remove_wait_queue(&ts->irq_wait, &wait);
ts->rtask = NULL;
return 0;
}
/*
* We only detect touch screen _touches_ with this interrupt
* handler, and even then we just schedule our task.
*/
static void ucb1x00_ts_irq(int idx, void *id)
{
struct ucb1x00_ts *ts = id;
ucb1x00_disable_irq(ts->ucb, UCB_IRQ_TSPX, UCB_FALLING);
wake_up(&ts->irq_wait);
}
static int ucb1x00_ts_open(struct input_dev *idev)
{
struct ucb1x00_ts *ts = input_get_drvdata(idev);
int ret = 0;
BUG_ON(ts->rtask);
init_waitqueue_head(&ts->irq_wait);
ret = ucb1x00_hook_irq(ts->ucb, UCB_IRQ_TSPX, ucb1x00_ts_irq, ts);
if (ret < 0)
goto out;
/*
* If we do this at all, we should allow the user to
* measure and read the X and Y resistance at any time.
*/
ucb1x00_adc_enable(ts->ucb);
ts->x_res = ucb1x00_ts_read_xres(ts);
ts->y_res = ucb1x00_ts_read_yres(ts);
ucb1x00_adc_disable(ts->ucb);
ts->rtask = kthread_run(ucb1x00_thread, ts, "ktsd");
if (!IS_ERR(ts->rtask)) {
ret = 0;
} else {
ucb1x00_free_irq(ts->ucb, UCB_IRQ_TSPX, ts);
ts->rtask = NULL;
ret = -EFAULT;
}
out:
return ret;
}
/*
* Release touchscreen resources. Disable IRQs.
*/
static void ucb1x00_ts_close(struct input_dev *idev)
{
struct ucb1x00_ts *ts = input_get_drvdata(idev);
if (ts->rtask)
kthread_stop(ts->rtask);
ucb1x00_enable(ts->ucb);
ucb1x00_free_irq(ts->ucb, UCB_IRQ_TSPX, ts);
ucb1x00_reg_write(ts->ucb, UCB_TS_CR, 0);
ucb1x00_disable(ts->ucb);
}
/*
* Initialisation.
*/
static int ucb1x00_ts_add(struct ucb1x00_dev *dev)
{
struct ucb1x00_ts *ts;
struct input_dev *idev;
int err;
ts = kzalloc(sizeof(struct ucb1x00_ts), GFP_KERNEL);
idev = input_allocate_device();
if (!ts || !idev) {
err = -ENOMEM;
goto fail;
}
ts->ucb = dev->ucb;
ts->idev = idev;
ts->adcsync = adcsync ? UCB_SYNC : UCB_NOSYNC;
idev->name = "Touchscreen panel";
idev->id.product = ts->ucb->id;
idev->open = ucb1x00_ts_open;
idev->close = ucb1x00_ts_close;
idev->evbit[0] = BIT_MASK(EV_ABS) | BIT_MASK(EV_KEY);
idev->keybit[BIT_WORD(BTN_TOUCH)] = BIT_MASK(BTN_TOUCH);
input_set_drvdata(idev, ts);
ucb1x00_adc_enable(ts->ucb);
ts->x_res = ucb1x00_ts_read_xres(ts);
ts->y_res = ucb1x00_ts_read_yres(ts);
ucb1x00_adc_disable(ts->ucb);
input_set_abs_params(idev, ABS_X, 0, ts->x_res, 0, 0);
input_set_abs_params(idev, ABS_Y, 0, ts->y_res, 0, 0);
input_set_abs_params(idev, ABS_PRESSURE, 0, 0, 0, 0);
err = input_register_device(idev);
if (err)
goto fail;
dev->priv = ts;
return 0;
fail:
input_free_device(idev);
kfree(ts);
return err;
}
static void ucb1x00_ts_remove(struct ucb1x00_dev *dev)
{
struct ucb1x00_ts *ts = dev->priv;
input_unregister_device(ts->idev);
kfree(ts);
}
static struct ucb1x00_driver ucb1x00_ts_driver = {
.add = ucb1x00_ts_add,
.remove = ucb1x00_ts_remove,
};
static int __init ucb1x00_ts_init(void)
{
return ucb1x00_register_driver(&ucb1x00_ts_driver);
}
static void __exit ucb1x00_ts_exit(void)
{
ucb1x00_unregister_driver(&ucb1x00_ts_driver);
}
module_param(adcsync, int, 0444);
module_init(ucb1x00_ts_init);
module_exit(ucb1x00_ts_exit);
MODULE_AUTHOR("Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION("UCB1x00 touchscreen driver");
MODULE_LICENSE("GPL");
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