[PATCH 2/4] Input: adp5588-keys - switch to using threaded interrupt

[Dmitry Torokhov <dmitry.torokhov@gmail.com>]

Instead of using hard interrupt handler and manually scheduling work
item to handle I2C communications, let's switch to threaded interrupt
handling.

While at that enforce the readout delay required on pre- revision 4
silicon.

Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
---
 drivers/input/keyboard/adp5588-keys.c | 81 +++++++++++++++------------
 1 file changed, 45 insertions(+), 36 deletions(-)

diff --git a/drivers/input/keyboard/adp5588-keys.c b/drivers/input/keyboard/adp5588-keys.c
index ea67d0834be1..ac21873ba1d7 100644
--- a/drivers/input/keyboard/adp5588-keys.c
+++ b/drivers/input/keyboard/adp5588-keys.c
@@ -8,17 +8,19 @@
  * Copyright (C) 2008-2010 Analog Devices Inc.
  */
 
-#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/gpio/driver.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
-#include <linux/workqueue.h>
-#include <linux/errno.h>
-#include <linux/pm.h>
+#include <linux/ktime.h>
+#include <linux/module.h>
 #include <linux/platform_device.h>
-#include <linux/input.h>
-#include <linux/i2c.h>
-#include <linux/gpio/driver.h>
+#include <linux/pm.h>
 #include <linux/slab.h>
+#include <linux/timekeeping.h>
 
 #include <linux/platform_data/adp5588.h>
 
@@ -36,11 +38,12 @@
  * asserted.
  */
 #define WA_DELAYED_READOUT_REVID(rev)		((rev) < 4)
+#define WA_DELAYED_READOUT_TIME			25
 
 struct adp5588_kpad {
 	struct i2c_client *client;
 	struct input_dev *input;
-	struct delayed_work work;
+	ktime_t irq_time;
 	unsigned long delay;
 	unsigned short keycode[ADP5588_KEYMAPSIZE];
 	const struct adp5588_gpi_map *gpimap;
@@ -289,13 +292,36 @@ static void adp5588_report_events(struct adp5588_kpad *kpad, int ev_cnt)
 	}
 }
 
-static void adp5588_work(struct work_struct *work)
+static irqreturn_t adp5588_hard_irq(int irq, void *handle)
+{
+	struct adp5588_kpad *kpad = handle;
+
+	kpad->irq_time = ktime_get();
+
+	return IRQ_WAKE_THREAD;
+}
+
+static irqreturn_t adp5588_thread_irq(int irq, void *handle)
 {
-	struct adp5588_kpad *kpad = container_of(work,
-						struct adp5588_kpad, work.work);
+	struct adp5588_kpad *kpad = handle;
 	struct i2c_client *client = kpad->client;
+	ktime_t target_time, now;
+	unsigned long delay;
 	int status, ev_cnt;
 
+	/*
+	 * Readout needs to wait for at least 25ms after the notification
+	 * for REVID < 4.
+	 */
+	if (kpad->delay) {
+		target_time = ktime_add_ms(kpad->irq_time, kpad->delay);
+		now = ktime_get();
+		if (ktime_before(now, target_time)) {
+			delay = ktime_to_us(ktime_sub(target_time, now));
+			usleep_range(delay, delay + 1000);
+		}
+	}
+
 	status = adp5588_read(client, INT_STAT);
 
 	if (status & ADP5588_OVR_FLOW_INT)	/* Unlikely and should never happen */
@@ -308,20 +334,8 @@ static void adp5588_work(struct work_struct *work)
 			input_sync(kpad->input);
 		}
 	}
-	adp5588_write(client, INT_STAT, status); /* Status is W1C */
-}
 
-static irqreturn_t adp5588_irq(int irq, void *handle)
-{
-	struct adp5588_kpad *kpad = handle;
-
-	/*
-	 * use keventd context to read the event fifo registers
-	 * Schedule readout at least 25ms after notification for
-	 * REVID < 4
-	 */
-
-	schedule_delayed_work(&kpad->work, kpad->delay);
+	adp5588_write(client, INT_STAT, status); /* Status is W1C */
 
 	return IRQ_HANDLED;
 }
@@ -505,7 +519,6 @@ static int adp5588_probe(struct i2c_client *client,
 
 	kpad->client = client;
 	kpad->input = input;
-	INIT_DELAYED_WORK(&kpad->work, adp5588_work);
 
 	ret = adp5588_read(client, DEV_ID);
 	if (ret < 0) {
@@ -515,7 +528,7 @@ static int adp5588_probe(struct i2c_client *client,
 
 	revid = (u8) ret & ADP5588_DEVICE_ID_MASK;
 	if (WA_DELAYED_READOUT_REVID(revid))
-		kpad->delay = msecs_to_jiffies(30);
+		kpad->delay = msecs_to_jiffies(WA_DELAYED_READOUT_TIME);
 
 	input->name = client->name;
 	input->phys = "adp5588-keys/input0";
@@ -560,9 +573,10 @@ static int adp5588_probe(struct i2c_client *client,
 		goto err_free_mem;
 	}
 
-	error = request_irq(client->irq, adp5588_irq,
-			    IRQF_TRIGGER_FALLING,
-			    client->dev.driver->name, kpad);
+	error = request_threaded_irq(client->irq,
+				     adp5588_hard_irq, adp5588_thread_irq,
+				     IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
+				     client->dev.driver->name, kpad);
 	if (error) {
 		dev_err(&client->dev, "irq %d busy?\n", client->irq);
 		goto err_unreg_dev;
@@ -587,7 +601,6 @@ static int adp5588_probe(struct i2c_client *client,
 
  err_free_irq:
 	free_irq(client->irq, kpad);
-	cancel_delayed_work_sync(&kpad->work);
  err_unreg_dev:
 	input_unregister_device(input);
 	input = NULL;
@@ -604,7 +617,6 @@ static int adp5588_remove(struct i2c_client *client)
 
 	adp5588_write(client, CFG, 0);
 	free_irq(client->irq, kpad);
-	cancel_delayed_work_sync(&kpad->work);
 	input_unregister_device(kpad->input);
 	adp5588_gpio_remove(kpad);
 	kfree(kpad);
@@ -614,11 +626,9 @@ static int adp5588_remove(struct i2c_client *client)
 
 static int __maybe_unused adp5588_suspend(struct device *dev)
 {
-	struct adp5588_kpad *kpad = dev_get_drvdata(dev);
-	struct i2c_client *client = kpad->client;
+	struct i2c_client *client = to_i2c_client(dev);
 
 	disable_irq(client->irq);
-	cancel_delayed_work_sync(&kpad->work);
 
 	if (device_may_wakeup(&client->dev))
 		enable_irq_wake(client->irq);
@@ -628,8 +638,7 @@ static int __maybe_unused adp5588_suspend(struct device *dev)
 
 static int __maybe_unused adp5588_resume(struct device *dev)
 {
-	struct adp5588_kpad *kpad = dev_get_drvdata(dev);
-	struct i2c_client *client = kpad->client;
+	struct i2c_client *client = to_i2c_client(dev);
 
 	if (device_may_wakeup(&client->dev))
 		disable_irq_wake(client->irq);
-- 
2.36.1.124.g0e6072fb45-goog