Input: dm355evm_keys - use threaded IRQs

Convert the dm355evm keys driver to use IRQ threading instead of
a private workqueue.  IRQ threads were added to Linux after this
driver was written, and in this case fit what the driver needs.
(Although the non-shared thread costs more runtime memory.)

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

1 files changed, 20 insertions, 22 deletions

diff --git a/drivers/input/misc/dm355evm_keys.c b/drivers/input/misc/dm355evm_keys.c
index a63315ce4a6c..0918acae584a 100644
--- a/drivers/input/misc/dm355evm_keys.c
+++ b/drivers/input/misc/dm355evm_keys.c
@@ -23,30 +23,16 @@
  * pressed, or its autorepeat kicks in, an event is sent.  This driver
  * read those events from the small (32 event) queue and reports them.
  *
- * Because we communicate with the MSP430 using I2C, and all I2C calls
- * in Linux sleep, we need to cons up a kind of threaded IRQ handler
- * using a work_struct.  The IRQ is active low, but we use it through
- * the GPIO controller so we can trigger on falling edges.
- *
  * Note that physically there can only be one of these devices.
  *
  * This driver was tested with firmware revision A4.
  */
 struct dm355evm_keys {
-        struct work_struct      work;
         struct input_dev        *input;
         struct device           *dev;
         int                     irq;
 };
 
-static irqreturn_t dm355evm_keys_irq(int irq, void *_keys)
-{
-        struct dm355evm_keys    *keys = _keys;
-
-        schedule_work(&keys->work);
-        return IRQ_HANDLED;
-}
-
 /* These initial keycodes can be remapped by dm355evm_setkeycode(). */
 static struct {
         u16     event;
@@ -110,13 +96,12 @@ static struct {
         { 0x3169, KEY_PAUSE, },
 };
 
-static void dm355evm_keys_work(struct work_struct *work)
+/* runs in an IRQ thread -- can (and will!) sleep */
+static irqreturn_t dm355evm_keys_irq(int irq, void *_keys)
 {
-        struct dm355evm_keys    *keys;
+        struct dm355evm_keys    *keys = _keys;
         int                     status;
 
-        keys = container_of(work, struct dm355evm_keys, work);
-
         /* For simplicity we ignore INPUT_COUNT and just read
          * events until we get the "queue empty" indicator.
          * Reading INPUT_LOW decrements the count.
@@ -183,6 +168,19 @@ static void dm355evm_keys_work(struct work_struct *work)
                 input_report_key(keys->input, keycode, 0);
                 input_sync(keys->input);
         }
+        return IRQ_HANDLED;
+}
+
+/*
+ * Because we communicate with the MSP430 using I2C, and all I2C calls
+ * in Linux sleep, we use a threaded IRQ handler.  The IRQ itself is
+ * active low, but we go through the GPIO controller so we can trigger
+ * on falling edges and not worry about enabling/disabling the IRQ in
+ * the keypress handling path.
+ */
+static irqreturn_t dm355evm_keys_hardirq(int irq, void *_keys)
+{
+        return IRQ_WAKE_THREAD;
 }
 
 static int dm355evm_setkeycode(struct input_dev *dev, int index, int keycode)
@@ -233,7 +231,6 @@ static int __devinit dm355evm_keys_probe(struct platform_device *pdev)
 
         keys->dev = &pdev->dev;
         keys->input = input;
-        INIT_WORK(&keys->work, dm355evm_keys_work);
 
         /* set up "threaded IRQ handler" */
         status = platform_get_irq(pdev, 0);
@@ -260,9 +257,10 @@ static int __devinit dm355evm_keys_probe(struct platform_device *pdev)
 
         /* REVISIT:  flush the event queue? */
 
-        status = request_irq(keys->irq, dm355evm_keys_irq,
-                             IRQF_TRIGGER_FALLING,
-                             dev_name(&pdev->dev), keys);
+        status = request_threaded_irq(keys->irq,
+                        dm355evm_keys_hardirq, dm355evm_keys_irq,
+                        IRQF_TRIGGER_FALLING,
+                        dev_name(&pdev->dev), keys);
         if (status < 0)
                 goto fail1;