In some cases it is possible for a device to be in its bootloader at
driver probe time.  This is detected by the driver when probe() is called
with an i2c_client which has one of the Atmel Bootloader i2c addresses.

In this case, we should load enough driver functionality to still loading
new firmware using:
  echo 1 > update_fw

However, we must be very careful not to follow any code paths that would try
to access the as-yet uninitialized object table or input device.
In particular:
 1) mxt_remove calls input_unregister_device on input_dev.
 2) mxt_suspend/resume reads and writes from the object table.
 3) Spurious or bootloader induced interrupts

Signed-off-by: Benson Leung <bleung@chromium.org>
Signed-off-by: Daniel Kurtz <redacted>
---
 drivers/input/touchscreen/atmel_mxt_ts.c | 51 +++++++++++++++++++++++++-------
 1 file changed, 40 insertions(+), 11 deletions(-)

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 9afc26e..6c2c712 100644
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c

@@ -324,6 +324,12 @@ static void mxt_dump_message(struct device *dev,
 		message->reportid, 7, message->message);
 }
 
+static bool mxt_in_bootloader(struct mxt_data *data)
+{
+	struct i2c_client *client = data->client;
+	return (client->addr == MXT_BOOT_LOW || client->addr == MXT_BOOT_HIGH);
+}
+
 static int mxt_i2c_recv(struct i2c_client *client, u8 *buf, size_t count)
 {
 	int ret;

@@ -584,6 +590,9 @@ static irqreturn_t mxt_interrupt(int irq, void *dev_id)
 	u8 reportid;
 	bool update_input = false;
 
+	if (mxt_in_bootloader(data))
+		goto end;
+
 	do {
 		if (mxt_read_message(data, &message)) {
 			dev_err(dev, "Failed to read message\n");

@@ -975,6 +984,9 @@ static int mxt_load_fw(struct device *dev, const char *fn)
 		return ret;
 	}
 
+	if (mxt_in_bootloader(data))
+		goto bootloader_ready;
+
 	/* Change to the bootloader mode */
 	mxt_write_object(data, MXT_GEN_COMMAND_T6,
 			MXT_COMMAND_RESET, MXT_BOOT_VALUE);

@@ -986,6 +998,7 @@ static int mxt_load_fw(struct device *dev, const char *fn)
 	else
 		client->addr = MXT_BOOT_HIGH;
 
+bootloader_ready:
 	ret = mxt_check_bootloader(client, MXT_WAITING_BOOTLOAD_CMD);
 	if (ret)
 		goto out;

@@ -1196,25 +1209,34 @@ static int __devinit mxt_probe(struct i2c_client *client,
 
 	mxt_calc_resolution(data);
 
-	error = mxt_initialize(data);
-	if (error)
-		goto err_free_mem;
+	if (mxt_in_bootloader(data)) {
+		dev_info(&client->dev, "Device in bootloader at probe\n");
+	} else {
+		error = mxt_initialize(data);
+		if (error)
+			goto err_free_mem;
 
-	error = mxt_input_dev_create(data);
-	if (error)
-		goto err_free_object;
+		error = mxt_input_dev_create(data);
+		if (error)
+			goto err_free_object;
+	}
 
 	error = request_threaded_irq(client->irq, NULL, mxt_interrupt,
 				     pdata->irqflags | IRQF_ONESHOT,
 				     client->name, data);
 	if (error) {
 		dev_err(&client->dev, "Failed to register interrupt\n");
-		goto err_unregister_device;
+		if (mxt_in_bootloader(data))
+			goto err_free_mem;
+		else
+			goto err_unregister_device;
 	}
 
-	error = mxt_make_highchg(data);
-	if (error)
-		goto err_free_irq;
+	if (!mxt_in_bootloader(data)) {
+		error = mxt_make_highchg(data);
+		if (error)
+			goto err_free_irq;
+	}
 
 	error = sysfs_create_group(&client->dev.kobj, &mxt_attr_group);
 	if (error)

@@ -1239,7 +1261,8 @@ static int mxt_remove(struct i2c_client *client)
 
 	sysfs_remove_group(&client->dev.kobj, &mxt_attr_group);
 	free_irq(data->irq, data);
-	input_unregister_device(data->input_dev);
+	if (data->input_dev)
+		input_unregister_device(data->input_dev);
 	kfree(data->object_table);
 	kfree(data);
 

@@ -1253,6 +1276,9 @@ static int mxt_suspend(struct device *dev)
 	struct mxt_data *data = i2c_get_clientdata(client);
 	struct input_dev *input_dev = data->input_dev;
 
+	if (mxt_in_bootloader(data))
+		return 0;
+

 	mutex_lock(&input_dev->mutex);
 
 	if (input_dev->users)

@@ -1269,6 +1295,9 @@ static int mxt_resume(struct device *dev)
 	struct mxt_data *data = i2c_get_clientdata(client);
 	struct input_dev *input_dev = data->input_dev;
 
+	if (mxt_in_bootloader(data))
+		return 0;
+
 	/* Soft reset */
 	mxt_write_object(data, MXT_GEN_COMMAND_T6,
 			MXT_COMMAND_RESET, 1);

-- 
1.8.1