Input: ucb1400_ts - convert to threaded IRQ

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>

1 files changed, 113 insertions, 122 deletions

diff --git a/drivers/input/touchscreen/ucb1400_ts.c b/drivers/input/touchscreen/ucb1400_ts.c
index 36ff1549434b..5162f4e34252 100644
--- a/drivers/input/touchscreen/ucb1400_ts.c
+++ b/drivers/input/touchscreen/ucb1400_ts.c
@@ -20,24 +20,24 @@
 
 #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,