[PATCH] Input: elan_i2c - Add i2c_reset in sysfs for ELAN touchpad recovery

[KT Liao]

Roger from SUSE reported the touchpad on Lenovo yoga2 crush sometimes.
He found that rmmod/modprobe elan_i2c will recover the issue.
He add the workaround on SUSE and solve the problem.
Recently, the workaround fails in kernel 4.20 becasue IRQ mismatch.
genirq: Flags mismatch irq 0. 00002002 (ELAN0600:00) vs. 00015a00 (timer)
I can't reproduce the issue in SUSE with the same kernel.
And it's a 5 years old laptop, ELAN can't find the module for testing.
Instead of IRQ debugging IRQ, I tried another approach.
I added i2c_reset in sysfs to avoid IRQ requesting in probe.

Signed-off-by: KT Liao <kt.liao@xxxxxxxxxx>
Acked-by: Roger Whittaker <Roger.Whittaker@xxxxxxxx>
---
 drivers/input/mouse/elan_i2c_core.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/drivers/input/mouse/elan_i2c_core.c b/drivers/input/mouse/elan_i2c_core.c
index 2690a4b..388b1f0 100644
--- a/drivers/input/mouse/elan_i2c_core.c
+++ b/drivers/input/mouse/elan_i2c_core.c
@@ -670,6 +670,29 @@ static ssize_t calibrate_store(struct device *dev,
 	return retval ?: count;
 }
 
+static ssize_t i2c_reset_store(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(dev);
+	struct elan_tp_data *data = i2c_get_clientdata(client);
+	int retval;
+
+	retval = mutex_lock_interruptible(&data->sysfs_mutex);
+	if (retval)
+		return retval;
+
+	disable_irq(client->irq);
+
+	retval = elan_initialize(data);
+	if (retval)
+		dev_err(dev, "failed to re-initialize touchpad: %d\n", retval);
+
+	enable_irq(client->irq);
+	mutex_unlock(&data->sysfs_mutex);
+	return retval ?: count;
+}
+
 static ssize_t elan_sysfs_read_mode(struct device *dev,
 				    struct device_attribute *attr,
 				    char *buf)
@@ -702,6 +725,7 @@ static DEVICE_ATTR(mode, S_IRUGO, elan_sysfs_read_mode, NULL);
 static DEVICE_ATTR(update_fw, S_IWUSR, NULL, elan_sysfs_update_fw);
 
 static DEVICE_ATTR_WO(calibrate);
+static DEVICE_ATTR_WO(i2c_reset);
 
 static struct attribute *elan_sysfs_entries[] = {
 	&dev_attr_product_id.attr,
@@ -710,6 +734,7 @@ static struct attribute *elan_sysfs_entries[] = {
 	&dev_attr_iap_version.attr,
 	&dev_attr_fw_checksum.attr,
 	&dev_attr_calibrate.attr,
+	&dev_attr_i2c_reset.attr,
 	&dev_attr_mode.attr,
 	&dev_attr_update_fw.attr,
 	NULL,
-- 
2.7.4