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kernel-ark/drivers/mfd/ucb1x00-ts.c
Rafael J. Wysocki 8314418629 Freezer: make kernel threads nonfreezable by default 
Currently, the freezer treats all tasks as freezable, except for the kernel
threads that explicitly set the PF_NOFREEZE flag for themselves.  This
approach is problematic, since it requires every kernel thread to either
set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't
care for the freezing of tasks at all.

It seems better to only require the kernel threads that want to or need to
be frozen to use some freezer-related code and to remove any
freezer-related code from the other (nonfreezable) kernel threads, which is
done in this patch.

The patch causes all kernel threads to be nonfreezable by default (ie.  to
have PF_NOFREEZE set by default) and introduces the set_freezable()
function that should be called by the freezable kernel threads in order to
unset PF_NOFREEZE.  It also makes all of the currently freezable kernel
threads call set_freezable(), so it shouldn't cause any (intentional)
change of behaviour to appear.  Additionally, it updates documentation to
describe the freezing of tasks more accurately.

[akpm@linux-foundation.org: build fixes]
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-17 10:23:02 -07:00

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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 <asm/dma.h>
#include <asm/semaphore.h>
#include <asm/arch/collie.h>
#include <asm/mach-types.h>
#include "ucb1x00.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 restart:1;
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_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_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;
struct task_struct *tsk = current;
DECLARE_WAITQUEUE(wait, tsk);
int valid = 0;
set_freezable();
add_wait_queue(&ts->irq_wait, &wait);
while (!kthread_should_stop()) {
unsigned int x, y, p;
signed long timeout;
ts->restart = 0;
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_task_state(tsk, 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 (!ts->restart) {
ucb1x00_ts_evt_add(ts, p, x, y);
valid = 1;
}
set_task_state(tsk, TASK_INTERRUPTIBLE);
timeout = HZ / 100;
}
try_to_freeze();
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);
}
#ifdef CONFIG_PM
static int ucb1x00_ts_resume(struct ucb1x00_dev *dev)
{
struct ucb1x00_ts *ts = dev->priv;
if (ts->rtask != NULL) {
/*
* Restart the TS thread to ensure the
* TS interrupt mode is set up again
* after sleep.
*/
ts->restart = 1;
wake_up(&ts->irq_wait);
}
return 0;
}
#else
#define ucb1x00_ts_resume NULL
#endif
/*
* 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;
__set_bit(EV_ABS, idev->evbit);
__set_bit(ABS_X, idev->absbit);
__set_bit(ABS_Y, idev->absbit);
__set_bit(ABS_PRESSURE, idev->absbit);
input_set_drvdata(idev, ts);
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,
.resume = ucb1x00_ts_resume,
};
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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