[PATCH v2 1/2] bus: mhi: host: Add sysfs entry to force device to enter EDL

[Qiang Yu]

Add sysfs entry to allow users of MHI bus force device to enter EDL.
Considering that the way to enter EDL mode varies from device to device and
some devices even do not support EDL. Hence, add a callback edl_trigger in
mhi controller as part of the sysfs entry to be invoked and MHI core will
only create EDL sysfs entry for mhi controller that provides edl_trigger
callback. All of the process a specific device required to enter EDL mode
can be placed in this callback.

Signed-off-by: Qiang Yu <quic_qianyu@xxxxxxxxxxx>
---
 drivers/bus/mhi/host/init.c | 35 +++++++++++++++++++++++++++++++++++
 include/linux/mhi.h         |  1 +
 2 files changed, 36 insertions(+)

diff --git a/drivers/bus/mhi/host/init.c b/drivers/bus/mhi/host/init.c
index 44f9349..333ac94 100644
--- a/drivers/bus/mhi/host/init.c
+++ b/drivers/bus/mhi/host/init.c
@@ -127,6 +127,32 @@ static ssize_t soc_reset_store(struct device *dev,
 }
 static DEVICE_ATTR_WO(soc_reset);
 
+static ssize_t force_edl_store(struct device *dev,
+			       struct device_attribute *attr,
+			       const char *buf, size_t count)
+{
+	struct mhi_device *mhi_dev = to_mhi_device(dev);
+	struct mhi_controller *mhi_cntrl = mhi_dev->mhi_cntrl;
+	unsigned long val;
+	int ret;
+
+	ret = kstrtoul(buf, 10, &val);
+	if (ret < 0) {
+		dev_err(dev, "Could not parse string: %d\n", ret);
+		return ret;
+	}
+
+	if (!val)
+		return count;
+
+	ret = mhi_cntrl->edl_trigger(mhi_cntrl);
+	if (ret)
+		return ret;
+
+	return count;
+}
+static DEVICE_ATTR_WO(force_edl);
+
 static struct attribute *mhi_dev_attrs[] = {
 	&dev_attr_serial_number.attr,
 	&dev_attr_oem_pk_hash.attr,
@@ -1018,6 +1044,12 @@ int mhi_register_controller(struct mhi_controller *mhi_cntrl,
 	if (ret)
 		goto err_release_dev;
 
+	if (mhi_cntrl->edl_trigger) {
+		ret = sysfs_create_file(&mhi_dev->dev.kobj, &dev_attr_force_edl.attr);
+		if (ret)
+			goto err_release_dev;
+	}
+
 	mhi_cntrl->mhi_dev = mhi_dev;
 
 	mhi_create_debugfs(mhi_cntrl);
@@ -1051,6 +1083,9 @@ void mhi_unregister_controller(struct mhi_controller *mhi_cntrl)
 	mhi_deinit_free_irq(mhi_cntrl);
 	mhi_destroy_debugfs(mhi_cntrl);
 
+	if (mhi_cntrl->edl_trigger)
+		sysfs_remove_file(&mhi_dev->dev.kobj, &dev_attr_force_edl.attr);
+
 	destroy_workqueue(mhi_cntrl->hiprio_wq);
 	kfree(mhi_cntrl->mhi_cmd);
 	kfree(mhi_cntrl->mhi_event);
diff --git a/include/linux/mhi.h b/include/linux/mhi.h
index cde01e1..8db56d7 100644
--- a/include/linux/mhi.h
+++ b/include/linux/mhi.h
@@ -435,6 +435,7 @@ struct mhi_controller {
 	void (*write_reg)(struct mhi_controller *mhi_cntrl, void __iomem *addr,
 			  u32 val);
 	void (*reset)(struct mhi_controller *mhi_cntrl);
+	int (*edl_trigger)(struct mhi_controller *mhi_cntrl);
 
 	size_t buffer_len;
 	int index;
-- 
2.7.4