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linux/drivers/input/touchscreen/ucb1400_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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/*
* Philips UCB1400 touchscreen driver
*
* Author: Nicolas Pitre
* Created: September 25, 2006
* Copyright: MontaVista Software, Inc.
*
* 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.
*
* This code is heavily based on ucb1x00-*.c copyrighted by Russell King
* covering the UCB1100, UCB1200 and UCB1300.. Support for the UCB1400 has
* been made separate from ucb1x00-core/ucb1x00-ts on Russell's request.
*/
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/delay.h>
#include <linux/input.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/freezer.h>
#include <sound/driver.h>
#include <sound/core.h>
#include <sound/ac97_codec.h>
/*
* Interesting UCB1400 AC-link registers
*/
#define UCB_IE_RIS 0x5e
#define UCB_IE_FAL 0x60
#define UCB_IE_STATUS 0x62
#define UCB_IE_CLEAR 0x62
#define UCB_IE_ADC (1 << 11)
#define UCB_IE_TSPX (1 << 12)
#define UCB_TS_CR 0x64
#define UCB_TS_CR_TSMX_POW (1 << 0)
#define UCB_TS_CR_TSPX_POW (1 << 1)
#define UCB_TS_CR_TSMY_POW (1 << 2)
#define UCB_TS_CR_TSPY_POW (1 << 3)
#define UCB_TS_CR_TSMX_GND (1 << 4)
#define UCB_TS_CR_TSPX_GND (1 << 5)
#define UCB_TS_CR_TSMY_GND (1 << 6)
#define UCB_TS_CR_TSPY_GND (1 << 7)
#define UCB_TS_CR_MODE_INT (0 << 8)
#define UCB_TS_CR_MODE_PRES (1 << 8)
#define UCB_TS_CR_MODE_POS (2 << 8)
#define UCB_TS_CR_BIAS_ENA (1 << 11)
#define UCB_TS_CR_TSPX_LOW (1 << 12)
#define UCB_TS_CR_TSMX_LOW (1 << 13)
#define UCB_ADC_CR 0x66
#define UCB_ADC_SYNC_ENA (1 << 0)
#define UCB_ADC_VREFBYP_CON (1 << 1)
#define UCB_ADC_INP_TSPX (0 << 2)
#define UCB_ADC_INP_TSMX (1 << 2)
#define UCB_ADC_INP_TSPY (2 << 2)
#define UCB_ADC_INP_TSMY (3 << 2)
#define UCB_ADC_INP_AD0 (4 << 2)
#define UCB_ADC_INP_AD1 (5 << 2)
#define UCB_ADC_INP_AD2 (6 << 2)
#define UCB_ADC_INP_AD3 (7 << 2)
#define UCB_ADC_EXT_REF (1 << 5)
#define UCB_ADC_START (1 << 7)
#define UCB_ADC_ENA (1 << 15)
#define UCB_ADC_DATA 0x68
#define UCB_ADC_DAT_VALID (1 << 15)
#define UCB_ADC_DAT_VALUE(x) ((x) & 0x3ff)
#define UCB_ID 0x7e
#define UCB_ID_1400 0x4304
struct ucb1400 {
struct snd_ac97 *ac97;
struct input_dev *ts_idev;
int irq;
wait_queue_head_t ts_wait;
struct task_struct *ts_task;
unsigned int irq_pending; /* not bit field shared */
unsigned int ts_restart:1;
unsigned int adcsync:1;
};
static int adcsync;
static int ts_delay = 55; /* us */
static int ts_delay_pressure; /* us */
static inline u16 ucb1400_reg_read(struct ucb1400 *ucb, u16 reg)
{
return ucb->ac97->bus->ops->read(ucb->ac97, reg);
}
static inline void ucb1400_reg_write(struct ucb1400 *ucb, u16 reg, u16 val)
{
ucb->ac97->bus->ops->write(ucb->ac97, reg, val);
}
static inline void ucb1400_adc_enable(struct ucb1400 *ucb)
{
ucb1400_reg_write(ucb, UCB_ADC_CR, UCB_ADC_ENA);
}
static unsigned int ucb1400_adc_read(struct ucb1400 *ucb, u16 adc_channel)
{
unsigned int val;
if (ucb->adcsync)
adc_channel |= UCB_ADC_SYNC_ENA;
ucb1400_reg_write(ucb, UCB_ADC_CR, UCB_ADC_ENA | adc_channel);
ucb1400_reg_write(ucb, UCB_ADC_CR, UCB_ADC_ENA | adc_channel | UCB_ADC_START);
for (;;) {
val = ucb1400_reg_read(ucb, UCB_ADC_DATA);
if (val & UCB_ADC_DAT_VALID)
break;
/* yield to other processes */
set_current_state(TASK_INTERRUPTIBLE);
schedule_timeout(1);
}
return UCB_ADC_DAT_VALUE(val);
}
static inline void ucb1400_adc_disable(struct ucb1400 *ucb)
{
ucb1400_reg_write(ucb, UCB_ADC_CR, 0);
}
/* Switch to interrupt mode. */
static inline void ucb1400_ts_mode_int(struct ucb1400 *ucb)
{
ucb1400_reg_write(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 ucb1400_ts_read_pressure(struct ucb1400 *ucb)
{
ucb1400_reg_write(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);
udelay(ts_delay_pressure);
return ucb1400_adc_read(ucb, UCB_ADC_INP_TSPY);
}
/*
* 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 ucb1400_ts_read_xpos(struct ucb1400 *ucb)
{
ucb1400_reg_write(ucb, UCB_TS_CR,
UCB_TS_CR_TSMX_GND | UCB_TS_CR_TSPX_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
ucb1400_reg_write(ucb, UCB_TS_CR,
UCB_TS_CR_TSMX_GND | UCB_TS_CR_TSPX_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
ucb1400_reg_write(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(ts_delay);
return ucb1400_adc_read(ucb, UCB_ADC_INP_TSPY);
}
/*
* 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 ucb1400_ts_read_ypos(struct ucb1400 *ucb)
{
ucb1400_reg_write(ucb, UCB_TS_CR,
UCB_TS_CR_TSMY_GND | UCB_TS_CR_TSPY_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
ucb1400_reg_write(ucb, UCB_TS_CR,
UCB_TS_CR_TSMY_GND | UCB_TS_CR_TSPY_POW |
UCB_TS_CR_MODE_PRES | UCB_TS_CR_BIAS_ENA);
ucb1400_reg_write(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(ts_delay);
return ucb1400_adc_read(ucb, UCB_ADC_INP_TSPX);
}
/*
* Switch to X plate resistance mode. Set MX to ground, PX to
* supply. Measure current.
*/
static inline unsigned int ucb1400_ts_read_xres(struct ucb1400 *ucb)
{
ucb1400_reg_write(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 ucb1400_adc_read(ucb, 0);
}
/*
* Switch to Y plate resistance mode. Set MY to ground, PY to
* supply. Measure current.
*/
static inline unsigned int ucb1400_ts_read_yres(struct ucb1400 *ucb)
{
ucb1400_reg_write(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 ucb1400_adc_read(ucb, 0);
}
static inline int ucb1400_ts_pen_down(struct ucb1400 *ucb)
{
unsigned short val = ucb1400_reg_read(ucb, UCB_TS_CR);
return (val & (UCB_TS_CR_TSPX_LOW | UCB_TS_CR_TSMX_LOW));
}
static inline void ucb1400_ts_irq_enable(struct ucb1400 *ucb)
{
ucb1400_reg_write(ucb, UCB_IE_CLEAR, UCB_IE_TSPX);
ucb1400_reg_write(ucb, UCB_IE_CLEAR, 0);
ucb1400_reg_write(ucb, UCB_IE_FAL, UCB_IE_TSPX);
}
static inline void ucb1400_ts_irq_disable(struct ucb1400 *ucb)
{
ucb1400_reg_write(ucb, UCB_IE_FAL, 0);
}
static void ucb1400_ts_evt_add(struct input_dev *idev, u16 pressure, u16 x, u16 y)
{
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 void ucb1400_ts_event_release(struct input_dev *idev)
{
input_report_abs(idev, ABS_PRESSURE, 0);
input_sync(idev);
}
static void ucb1400_handle_pending_irq(struct ucb1400 *ucb)
{
unsigned int isr;
isr = ucb1400_reg_read(ucb, UCB_IE_STATUS);
ucb1400_reg_write(ucb, UCB_IE_CLEAR, isr);
ucb1400_reg_write(ucb, UCB_IE_CLEAR, 0);
if (isr & UCB_IE_TSPX)
ucb1400_ts_irq_disable(ucb);
else
printk(KERN_ERR "ucb1400: unexpected IE_STATUS = %#x\n", isr);
enable_irq(ucb->irq);
}
static int ucb1400_ts_thread(void *_ucb)
{
struct ucb1400 *ucb = _ucb;
struct task_struct *tsk = current;
int valid = 0;
struct sched_param param = { .sched_priority = 1 };
sched_setscheduler(tsk, SCHED_FIFO, &param);
set_freezable();
while (!kthread_should_stop()) {
unsigned int x, y, p;
long timeout;
ucb->ts_restart = 0;
if (ucb->irq_pending) {
ucb->irq_pending = 0;
ucb1400_handle_pending_irq(ucb);
}
ucb1400_adc_enable(ucb);
x = ucb1400_ts_read_xpos(ucb);
y = ucb1400_ts_read_ypos(ucb);
p = ucb1400_ts_read_pressure(ucb);
ucb1400_adc_disable(ucb);
/* Switch back to interrupt mode. */
ucb1400_ts_mode_int(ucb);
msleep(10);
if (ucb1400_ts_pen_down(ucb)) {
ucb1400_ts_irq_enable(ucb);
/*
* If we spat out a valid sample set last time,
* spit out a "pen off" sample here.
*/
if (valid) {
ucb1400_ts_event_release(ucb->ts_idev);
valid = 0;
}
timeout = MAX_SCHEDULE_TIMEOUT;
} else {
valid = 1;
ucb1400_ts_evt_add(ucb->ts_idev, p, x, y);
timeout = msecs_to_jiffies(10);
}
wait_event_interruptible_timeout(ucb->ts_wait,
ucb->irq_pending || ucb->ts_restart || kthread_should_stop(),
timeout);
try_to_freeze();
}
/* Send the "pen off" if we are stopping with the pen still active */
if (valid)
ucb1400_ts_event_release(ucb->ts_idev);
ucb->ts_task = NULL;
return 0;
}
/*
* A restriction with interrupts exists when using the ucb1400, as
* the codec read/write routines may sleep while waiting for codec
* access completion and uses semaphores for access control to the
* AC97 bus. A complete codec read cycle could take anywhere from
* 60 to 100uSec so we *definitely* don't want to spin inside the
* interrupt handler waiting for codec access. So, we handle the
* interrupt by scheduling a RT kernel thread to run in process
* context instead of interrupt context.
*/
static irqreturn_t ucb1400_hard_irq(int irqnr, void *devid)
{
struct ucb1400 *ucb = devid;
if (irqnr == ucb->irq) {
disable_irq(ucb->irq);
ucb->irq_pending = 1;
wake_up(&ucb->ts_wait);
return IRQ_HANDLED;
}
return IRQ_NONE;
}
static int ucb1400_ts_open(struct input_dev *idev)
{
struct ucb1400 *ucb = input_get_drvdata(idev);
int ret = 0;
BUG_ON(ucb->ts_task);
ucb->ts_task = kthread_run(ucb1400_ts_thread, ucb, "UCB1400_ts");
if (IS_ERR(ucb->ts_task)) {
ret = PTR_ERR(ucb->ts_task);
ucb->ts_task = NULL;
}
return ret;
}
static void ucb1400_ts_close(struct input_dev *idev)
{
struct ucb1400 *ucb = input_get_drvdata(idev);
if (ucb->ts_task)
kthread_stop(ucb->ts_task);
ucb1400_ts_irq_disable(ucb);
ucb1400_reg_write(ucb, UCB_TS_CR, 0);
}
#ifdef CONFIG_PM
static int ucb1400_ts_resume(struct device *dev)
{
struct ucb1400 *ucb = dev_get_drvdata(dev);
if (ucb->ts_task) {
/*
* Restart the TS thread to ensure the
* TS interrupt mode is set up again
* after sleep.
*/
ucb->ts_restart = 1;
wake_up(&ucb->ts_wait);
}
return 0;
}
#else
#define ucb1400_ts_resume NULL
#endif
#ifndef NO_IRQ
#define NO_IRQ 0
#endif
/*
* Try to probe our interrupt, rather than relying on lots of
* hard-coded machine dependencies.
*/
static int ucb1400_detect_irq(struct ucb1400 *ucb)
{
unsigned long mask, timeout;
mask = probe_irq_on();
if (!mask) {
probe_irq_off(mask);
return -EBUSY;
}
/* Enable the ADC interrupt. */
ucb1400_reg_write(ucb, UCB_IE_RIS, UCB_IE_ADC);
ucb1400_reg_write(ucb, UCB_IE_FAL, UCB_IE_ADC);
ucb1400_reg_write(ucb, UCB_IE_CLEAR, 0xffff);
ucb1400_reg_write(ucb, UCB_IE_CLEAR, 0);
/* Cause an ADC interrupt. */
ucb1400_reg_write(ucb, UCB_ADC_CR, UCB_ADC_ENA);
ucb1400_reg_write(ucb, UCB_ADC_CR, UCB_ADC_ENA | UCB_ADC_START);
/* Wait for the conversion to complete. */
timeout = jiffies + HZ/2;
while (!(ucb1400_reg_read(ucb, UCB_ADC_DATA) & UCB_ADC_DAT_VALID)) {
cpu_relax();
if (time_after(jiffies, timeout)) {
printk(KERN_ERR "ucb1400: timed out in IRQ probe\n");
probe_irq_off(mask);
return -ENODEV;
}
}
ucb1400_reg_write(ucb, UCB_ADC_CR, 0);
/* Disable and clear interrupt. */
ucb1400_reg_write(ucb, UCB_IE_RIS, 0);
ucb1400_reg_write(ucb, UCB_IE_FAL, 0);
ucb1400_reg_write(ucb, UCB_IE_CLEAR, 0xffff);
ucb1400_reg_write(ucb, UCB_IE_CLEAR, 0);
/* Read triggered interrupt. */
ucb->irq = probe_irq_off(mask);
if (ucb->irq < 0 || ucb->irq == NO_IRQ)
return -ENODEV;
return 0;
}
static int ucb1400_ts_probe(struct device *dev)
{
struct ucb1400 *ucb;
struct input_dev *idev;
int error, id, x_res, y_res;
ucb = kzalloc(sizeof(struct ucb1400), GFP_KERNEL);
idev = input_allocate_device();
if (!ucb || !idev) {
error = -ENOMEM;
goto err_free_devs;
}
ucb->ts_idev = idev;
ucb->adcsync = adcsync;
ucb->ac97 = to_ac97_t(dev);
init_waitqueue_head(&ucb->ts_wait);
id = ucb1400_reg_read(ucb, UCB_ID);
if (id != UCB_ID_1400) {
error = -ENODEV;
goto err_free_devs;
}
error = ucb1400_detect_irq(ucb);
if (error) {
printk(KERN_ERR "UCB1400: IRQ probe failed\n");
goto err_free_devs;
}
error = request_irq(ucb->irq, ucb1400_hard_irq, IRQF_TRIGGER_RISING,
"UCB1400", ucb);
if (error) {
printk(KERN_ERR "ucb1400: unable to grab irq%d: %d\n",
ucb->irq, error);
goto err_free_devs;
}
printk(KERN_DEBUG "UCB1400: found IRQ %d\n", ucb->irq);
input_set_drvdata(idev, ucb);
idev->dev.parent = dev;
idev->name = "UCB1400 touchscreen interface";
idev->id.vendor = ucb1400_reg_read(ucb, AC97_VENDOR_ID1);
idev->id.product = id;
idev->open = ucb1400_ts_open;
idev->close = ucb1400_ts_close;
idev->evbit[0] = BIT(EV_ABS);
ucb1400_adc_enable(ucb);
x_res = ucb1400_ts_read_xres(ucb);
y_res = ucb1400_ts_read_yres(ucb);
ucb1400_adc_disable(ucb);
printk(KERN_DEBUG "UCB1400: x/y = %d/%d\n", x_res, y_res);
input_set_abs_params(idev, ABS_X, 0, x_res, 0, 0);
input_set_abs_params(idev, ABS_Y, 0, y_res, 0, 0);
input_set_abs_params(idev, ABS_PRESSURE, 0, 0, 0, 0);
error = input_register_device(idev);
if (error)
goto err_free_irq;
dev_set_drvdata(dev, ucb);
return 0;
err_free_irq:
free_irq(ucb->irq, ucb);
err_free_devs:
input_free_device(idev);
kfree(ucb);
return error;
}
static int ucb1400_ts_remove(struct device *dev)
{
struct ucb1400 *ucb = dev_get_drvdata(dev);
free_irq(ucb->irq, ucb);
input_unregister_device(ucb->ts_idev);
dev_set_drvdata(dev, NULL);
kfree(ucb);
return 0;
}
static struct device_driver ucb1400_ts_driver = {
.name = "ucb1400_ts",
.owner = THIS_MODULE,
.bus = &ac97_bus_type,
.probe = ucb1400_ts_probe,
.remove = ucb1400_ts_remove,
.resume = ucb1400_ts_resume,
};
static int __init ucb1400_ts_init(void)
{
return driver_register(&ucb1400_ts_driver);
}
static void __exit ucb1400_ts_exit(void)
{
driver_unregister(&ucb1400_ts_driver);
}
module_param(adcsync, bool, 0444);
MODULE_PARM_DESC(adcsync, "Synchronize touch readings with ADCSYNC pin.");
module_param(ts_delay, int, 0444);
MODULE_PARM_DESC(ts_delay, "Delay between panel setup and position read. Default = 55us.");
module_param(ts_delay_pressure, int, 0444);
MODULE_PARM_DESC(ts_delay_pressure,
"delay between panel setup and pressure read. Default = 0us.");
module_init(ucb1400_ts_init);
module_exit(ucb1400_ts_exit);
MODULE_DESCRIPTION("Philips UCB1400 touchscreen driver");
MODULE_LICENSE("GPL");
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