Input: ucb1400_ts - convert to threaded IRQ
authorDmitry Torokhov <dmitry.torokhov@gmail.com>
Thu, 5 Jan 2012 06:18:42 +0000 (22:18 -0800)
committerDmitry Torokhov <dmitry.torokhov@gmail.com>
Thu, 5 Jan 2012 06:19:55 +0000 (22:19 -0800)
Instead of manually create and handler kernel thread switch to threaded
IRQ and let kernel IRQ core manage thread for us.

Acked-by: Marek Vasut <marek.vasut@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
drivers/input/touchscreen/ucb1400_ts.c
include/linux/ucb1400.h

index 36ff154..5162f4e 100644 (file)
 
 #include <linux/module.h>
 #include <linux/init.h>
-#include <linux/completion.h>
 #include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
 #include <linux/input.h>
 #include <linux/device.h>
 #include <linux/interrupt.h>
-#include <linux/suspend.h>
-#include <linux/kthread.h>
-#include <linux/freezer.h>
 #include <linux/ucb1400.h>
 
+#define UCB1400_TS_POLL_PERIOD 10 /* ms */
+
 static int adcsync;
 static int ts_delay = 55; /* us */
 static int ts_delay_pressure;  /* us */
 
 /* Switch to interrupt mode. */
-static void ucb1400_ts_mode_int(struct snd_ac97 *ac97)
+static void ucb1400_ts_mode_int(struct ucb1400_ts *ucb)
 {
-       ucb1400_reg_write(ac97, UCB_TS_CR,
+       ucb1400_reg_write(ucb->ac97, 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);
@@ -53,7 +53,9 @@ static unsigned int ucb1400_ts_read_pressure(struct ucb1400_ts *ucb)
                        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->ac97, UCB_ADC_INP_TSPY, adcsync);
 }
 
@@ -127,26 +129,26 @@ static unsigned int ucb1400_ts_read_yres(struct ucb1400_ts *ucb)
        return ucb1400_adc_read(ucb->ac97, 0, adcsync);
 }
 
-static int ucb1400_ts_pen_up(struct snd_ac97 *ac97)
+static int ucb1400_ts_pen_up(struct ucb1400_ts *ucb)
 {
-       unsigned short val = ucb1400_reg_read(ac97, UCB_TS_CR);
+       unsigned short val = ucb1400_reg_read(ucb->ac97, UCB_TS_CR);
 
        return val & (UCB_TS_CR_TSPX_LOW | UCB_TS_CR_TSMX_LOW);
 }
 
-static void ucb1400_ts_irq_enable(struct snd_ac97 *ac97)
+static void ucb1400_ts_irq_enable(struct ucb1400_ts *ucb)
 {
-       ucb1400_reg_write(ac97, UCB_IE_CLEAR, UCB_IE_TSPX);
-       ucb1400_reg_write(ac97, UCB_IE_CLEAR, 0);
-       ucb1400_reg_write(ac97, UCB_IE_FAL, UCB_IE_TSPX);
+       ucb1400_reg_write(ucb->ac97, UCB_IE_CLEAR, UCB_IE_TSPX);
+       ucb1400_reg_write(ucb->ac97, UCB_IE_CLEAR, 0);
+       ucb1400_reg_write(ucb->ac97, UCB_IE_FAL, UCB_IE_TSPX);
 }
 
-static void ucb1400_ts_irq_disable(struct snd_ac97 *ac97)
+static void ucb1400_ts_irq_disable(struct ucb1400_ts *ucb)
 {
-       ucb1400_reg_write(ac97, UCB_IE_FAL, 0);
+       ucb1400_reg_write(ucb->ac97, UCB_IE_FAL, 0);
 }
 
-static void ucb1400_ts_evt_add(struct input_dev *idev, u16 pressure, u16 x, u16 y)
+static void ucb1400_ts_report_event(struct input_dev *idev, u16 pressure, u16 x, u16 y)
 {
        input_report_abs(idev, ABS_X, x);
        input_report_abs(idev, ABS_Y, y);
@@ -162,7 +164,7 @@ static void ucb1400_ts_event_release(struct input_dev *idev)
        input_sync(idev);
 }
 
-static void ucb1400_handle_pending_irq(struct ucb1400_ts *ucb)
+static void ucb1400_clear_pending_irq(struct ucb1400_ts *ucb)
 {
        unsigned int isr;
 
@@ -171,32 +173,34 @@ static void ucb1400_handle_pending_irq(struct ucb1400_ts *ucb)
        ucb1400_reg_write(ucb->ac97, UCB_IE_CLEAR, 0);
 
        if (isr & UCB_IE_TSPX)
-               ucb1400_ts_irq_disable(ucb->ac97);
+               ucb1400_ts_irq_disable(ucb);
        else
-               dev_dbg(&ucb->ts_idev->dev, "ucb1400: unexpected IE_STATUS = %#x\n", isr);
-       enable_irq(ucb->irq);
+               dev_dbg(&ucb->ts_idev->dev,
+                       "ucb1400: unexpected IE_STATUS = %#x\n", isr);
 }
 
-static int ucb1400_ts_thread(void *_ucb)
+/*
+ * 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. Therefore the driver is forced to use threaded interrupt
+ * handler.
+ */
+static irqreturn_t ucb1400_irq(int irqnr, void *devid)
 {
-       struct ucb1400_ts *ucb = _ucb;
-       struct task_struct *tsk = current;
-       int valid = 0;
-       struct sched_param param = { .sched_priority = 1 };
+       struct ucb1400_ts *ucb = devid;
+       unsigned int x, y, p;
+       bool penup;
 
-       sched_setscheduler(tsk, SCHED_FIFO, &param);
+       if (unlikely(irqnr != ucb->irq))
+               return IRQ_NONE;
 
-       set_freezable();
-       while (!kthread_should_stop()) {
-               unsigned int x, y, p;
-               long timeout;
+       ucb1400_clear_pending_irq(ucb);
 
-               ucb->ts_restart = 0;
+       /* Start with a small delay before checking pendown state */
+       msleep(UCB1400_TS_POLL_PERIOD);
 
-               if (ucb->irq_pending) {
-                       ucb->irq_pending = 0;
-                       ucb1400_handle_pending_irq(ucb);
-               }
+       while (!ucb->stopped && !(penup = ucb1400_ts_pen_up(ucb))) {
 
                ucb1400_adc_enable(ucb->ac97);
                x = ucb1400_ts_read_xpos(ucb);
@@ -204,91 +208,62 @@ static int ucb1400_ts_thread(void *_ucb)
                p = ucb1400_ts_read_pressure(ucb);
                ucb1400_adc_disable(ucb->ac97);
 
-               /* Switch back to interrupt mode. */
-               ucb1400_ts_mode_int(ucb->ac97);
-
-               msleep(10);
-
-               if (ucb1400_ts_pen_up(ucb->ac97)) {
-                       ucb1400_ts_irq_enable(ucb->ac97);
-
-                       /*
-                        * 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);
-               }
+               ucb1400_ts_report_event(ucb->ts_idev, p, x, y);
 
-               wait_event_freezable_timeout(ucb->ts_wait,
-                       ucb->irq_pending || ucb->ts_restart ||
-                       kthread_should_stop(), timeout);
+               wait_event_timeout(ucb->ts_wait, ucb->stopped,
+                                  msecs_to_jiffies(UCB1400_TS_POLL_PERIOD));
        }
 
-       /* Send the "pen off" if we are stopping with the pen still active */
-       if (valid)
-               ucb1400_ts_event_release(ucb->ts_idev);
+       ucb1400_ts_event_release(ucb->ts_idev);
 
-       ucb->ts_task = NULL;
-       return 0;
+       if (!ucb->stopped) {
+               /* Switch back to interrupt mode. */
+               ucb1400_ts_mode_int(ucb);
+               ucb1400_ts_irq_enable(ucb);
+       }
+
+       return IRQ_HANDLED;
 }
 
-/*
- * 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)
+static void ucb1400_ts_stop(struct ucb1400_ts *ucb)
 {
-       struct ucb1400_ts *ucb = devid;
+       /* Signal IRQ thread to stop polling and disable the handler. */
+       ucb->stopped = true;
+       mb();
+       wake_up(&ucb->ts_wait);
+       disable_irq(ucb->irq);
 
-       if (irqnr == ucb->irq) {
-               disable_irq_nosync(ucb->irq);
-               ucb->irq_pending = 1;
-               wake_up(&ucb->ts_wait);
-               return IRQ_HANDLED;
-       }
-       return IRQ_NONE;
+       ucb1400_ts_irq_disable(ucb);
+       ucb1400_reg_write(ucb->ac97, UCB_TS_CR, 0);
+}
+
+/* Must be called with ts->lock held */
+static void ucb1400_ts_start(struct ucb1400_ts *ucb)
+{
+       /* Tell IRQ thread that it may poll the device. */
+       ucb->stopped = false;
+       mb();
+
+       ucb1400_ts_mode_int(ucb);
+       ucb1400_ts_irq_enable(ucb);
+
+       enable_irq(ucb->irq);
 }
 
 static int ucb1400_ts_open(struct input_dev *idev)
 {
        struct ucb1400_ts *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;
-       }
+       ucb1400_ts_start(ucb);
 
-       return ret;
+       return 0;
 }
 
 static void ucb1400_ts_close(struct input_dev *idev)
 {
        struct ucb1400_ts *ucb = input_get_drvdata(idev);
 
-       if (ucb->ts_task)
-               kthread_stop(ucb->ts_task);
-
-       ucb1400_ts_irq_disable(ucb->ac97);
-       ucb1400_reg_write(ucb->ac97, UCB_TS_CR, 0);
+       ucb1400_ts_stop(ucb);
 }
 
 #ifndef NO_IRQ
@@ -342,11 +317,11 @@ static int __devinit ucb1400_ts_detect_irq(struct ucb1400_ts *ucb)
        return 0;
 }
 
-static int __devinit ucb1400_ts_probe(struct platform_device *dev)
+static int __devinit ucb1400_ts_probe(struct platform_device *pdev)
 {
+       struct ucb1400_ts *ucb = pdev->dev.platform_data;
        int error, x_res, y_res;
        u16 fcsr;
-       struct ucb1400_ts *ucb = dev->dev.platform_data;
 
        ucb->ts_idev = input_allocate_device();
        if (!ucb->ts_idev) {
@@ -362,21 +337,13 @@ static int __devinit ucb1400_ts_probe(struct platform_device *dev)
                        goto err_free_devs;
                }
        }
+       printk(KERN_DEBUG "UCB1400: found IRQ %d\n", ucb->irq);
 
        init_waitqueue_head(&ucb->ts_wait);
 
-       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(ucb->ts_idev, ucb);
 
-       ucb->ts_idev->dev.parent        = &dev->dev;
+       ucb->ts_idev->dev.parent        = &pdev->dev;
        ucb->ts_idev->name              = "UCB1400 touchscreen interface";
        ucb->ts_idev->id.vendor         = ucb1400_reg_read(ucb->ac97,
                                                AC97_VENDOR_ID1);
@@ -404,6 +371,17 @@ static int __devinit ucb1400_ts_probe(struct platform_device *dev)
        input_set_abs_params(ucb->ts_idev, ABS_Y, 0, y_res, 0, 0);
        input_set_abs_params(ucb->ts_idev, ABS_PRESSURE, 0, 0, 0, 0);
 
+       ucb1400_ts_stop(ucb);
+
+       error = request_threaded_irq(ucb->irq, NULL, ucb1400_irq,
+                                    IRQF_TRIGGER_RISING | IRQF_ONESHOT,
+                                    "UCB1400", ucb);
+       if (error) {
+               printk(KERN_ERR "ucb1400: unable to grab irq%d: %d\n",
+                               ucb->irq, error);
+               goto err_free_devs;
+       }
+
        error = input_register_device(ucb->ts_idev);
        if (error)
                goto err_free_irq;
@@ -418,9 +396,9 @@ err:
        return error;
 }
 
-static int __devexit ucb1400_ts_remove(struct platform_device *dev)
+static int __devexit ucb1400_ts_remove(struct platform_device *pdev)
 {
-       struct ucb1400_ts *ucb = dev->dev.platform_data;
+       struct ucb1400_ts *ucb = pdev->dev.platform_data;
 
        free_irq(ucb->irq, ucb);
        input_unregister_device(ucb->ts_idev);
@@ -429,24 +407,37 @@ static int __devexit ucb1400_ts_remove(struct platform_device *dev)
 }
 
 #ifdef CONFIG_PM_SLEEP
+static int ucb1400_ts_suspend(struct device *dev)
+{
+       struct ucb1400_ts *ucb = dev->platform_data;
+       struct input_dev *idev = ucb->ts_idev;
+
+       mutex_lock(&idev->mutex);
+
+       if (idev->users)
+               ucb1400_ts_start(ucb);
+
+       mutex_unlock(&idev->mutex);
+       return 0;
+}
+
 static int ucb1400_ts_resume(struct device *dev)
 {
        struct ucb1400_ts *ucb = dev->platform_data;
+       struct input_dev *idev = ucb->ts_idev;
 
-       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);
-       }
+       mutex_lock(&idev->mutex);
+
+       if (idev->users)
+               ucb1400_ts_stop(ucb);
+
+       mutex_unlock(&idev->mutex);
        return 0;
 }
 #endif
 
-static SIMPLE_DEV_PM_OPS(ucb1400_ts_pm_ops, NULL, ucb1400_ts_resume);
+static SIMPLE_DEV_PM_OPS(ucb1400_ts_pm_ops,
+                        ucb1400_ts_suspend, ucb1400_ts_resume);
 
 static struct platform_driver ucb1400_ts_driver = {
        .probe  = ucb1400_ts_probe,
index 5c75153..d21b33c 100644 (file)
@@ -96,13 +96,11 @@ struct ucb1400_gpio {
 
 struct ucb1400_ts {
        struct input_dev        *ts_idev;
-       struct task_struct      *ts_task;
        int                     id;
-       wait_queue_head_t       ts_wait;
-       unsigned int            ts_restart:1;
        int                     irq;
-       unsigned int            irq_pending;    /* not bit field shared */
        struct snd_ac97         *ac97;
+       wait_queue_head_t       ts_wait;
+       bool                    stopped;
 };
 
 struct ucb1400 {