Input: iqs5xx - make reset GPIO optional

The device's hardware reset pin is only required if the platform
must be able to update the device's firmware.

As such, demote the reset GPIO to optional in support of devices
that ship with pre-programmed firmware and don't route the reset
pin back to the SoC.

In that case, the 'fw_file' attribute is hidden because there is
no way to open the bootloader. The logic is extended to the case
in which the device does not advertise bootloader support in the
first place.

Last but not least, remove the hardware reset performed at probe
because there is no reason to reset the device manually. A power
on reset function already ensures a clean reset at start-up.

Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Link: https://lore.kernel.org/r/20210323021006.367-1-jeff@labundy.com
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/touchscreen/iqs5xx.c

@@ -835,9 +835,6 @@ static int iqs5xx_fw_file_write(struct i2c_client *client, const char *fw_file)
 	int error, error_init = 0;
 	u8 *pmap;
 
-	if (iqs5xx->dev_id_info.bl_status == IQS5XX_BL_STATUS_NONE)
-		return -EPERM;
-
 	pmap = kzalloc(IQS5XX_PMAP_LEN, GFP_KERNEL);
 	if (!pmap)
 		return -ENOMEM;
@@ -963,7 +960,22 @@ static struct attribute *iqs5xx_attrs[] = {
 	NULL,
 };
 
+static umode_t iqs5xx_attr_is_visible(struct kobject *kobj,
+				      struct attribute *attr, int i)
+{
+	struct device *dev = kobj_to_dev(kobj);
+	struct iqs5xx_private *iqs5xx = dev_get_drvdata(dev);
+
+	if (attr == &dev_attr_fw_file.attr &&
+	    (iqs5xx->dev_id_info.bl_status == IQS5XX_BL_STATUS_NONE ||
+	    !iqs5xx->reset_gpio))
+		return 0;
+
+	return attr->mode;
+}
+
 static const struct attribute_group iqs5xx_attr_group = {
+	.is_visible = iqs5xx_attr_is_visible,
 	.attrs = iqs5xx_attrs,
 };
 
@@ -1020,8 +1032,8 @@ static int iqs5xx_probe(struct i2c_client *client,
 	i2c_set_clientdata(client, iqs5xx);
 	iqs5xx->client = client;
 
-	iqs5xx->reset_gpio = devm_gpiod_get(&client->dev,
-					    "reset", GPIOD_OUT_LOW);
+	iqs5xx->reset_gpio = devm_gpiod_get_optional(&client->dev,
+						     "reset", GPIOD_OUT_LOW);
 	if (IS_ERR(iqs5xx->reset_gpio)) {
 		error = PTR_ERR(iqs5xx->reset_gpio);
 		dev_err(&client->dev, "Failed to request GPIO: %d\n", error);
@@ -1030,9 +1042,6 @@ static int iqs5xx_probe(struct i2c_client *client,
 
 	mutex_init(&iqs5xx->lock);
 
-	iqs5xx_reset(client);
-	usleep_range(10000, 10100);
-
 	error = iqs5xx_dev_init(client);
 	if (error)
 		return error;