[PATCH 2/4] soc: qcom: aoss: Add debugfs interface for sending messages

[Bjorn Andersson]

From: Chris Lew <clew@xxxxxxxxxxxxxx>

In addition to the normal runtime commands, the Always On Processor
(AOP) provides a number of debug commands which can be used during
system debugging for things such as preventing power collapse or placing
floor votes for certain resources. Some of these are documented in the
Robotics RB5 "Debug AOP ADB" linked below.

Provide a debugfs interface for the developer/tester to send these
commands to the AOP.

Link: https://docs.qualcomm.com/bundle/publicresource/topics/80-88500-3/85_Debugging_AOP_ADB.html
Signed-off-by: Chris Lew <clew@xxxxxxxxxxxxxx>
[bjorn: Dropped debugfs guards, improve error codes, rewrote commit message]
Signed-off-by: Bjorn Andersson <quic_bjorande@xxxxxxxxxxx>
---
 drivers/soc/qcom/qcom_aoss.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c
index 5e74332515cf..4c5bb7034fff 100644
--- a/drivers/soc/qcom/qcom_aoss.c
+++ b/drivers/soc/qcom/qcom_aoss.c
@@ -3,6 +3,7 @@
  * Copyright (c) 2019, Linaro Ltd
  */
 #include <linux/clk-provider.h>
+#include <linux/debugfs.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/mailbox_client.h>
@@ -82,6 +83,7 @@ struct qmp {
 
 	struct clk_hw qdss_clk;
 	struct qmp_cooling_device *cooling_devs;
+	struct dentry *debugfs_file;
 };
 
 static void qmp_kick(struct qmp *qmp)
@@ -475,6 +477,32 @@ void qmp_put(struct qmp *qmp)
 }
 EXPORT_SYMBOL(qmp_put);
 
+static ssize_t qmp_debugfs_write(struct file *file, const char __user *userstr,
+				 size_t len, loff_t *pos)
+{
+	struct qmp *qmp = file->private_data;
+	char buf[QMP_MSG_LEN];
+	int ret;
+
+	if (!len || len > QMP_MSG_LEN)
+		return -EINVAL;
+
+	if (copy_from_user(buf, userstr, len))
+		return -EFAULT;
+	buf[len] = '\0';
+
+	ret = qmp_send(qmp, buf);
+	if (ret < 0)
+		return ret;
+
+	return len;
+}
+
+static const struct file_operations qmp_debugfs_fops = {
+	.open = simple_open,
+	.write = qmp_debugfs_write,
+};
+
 static int qmp_probe(struct platform_device *pdev)
 {
 	struct qmp *qmp;
@@ -523,6 +551,9 @@ static int qmp_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, qmp);
 
+	qmp->debugfs_file = debugfs_create_file("aoss_send_message", 0220, NULL,
+						qmp, &qmp_debugfs_fops);
+
 	return 0;
 
 err_close_qmp:
@@ -537,6 +568,8 @@ static int qmp_remove(struct platform_device *pdev)
 {
 	struct qmp *qmp = platform_get_drvdata(pdev);
 
+	debugfs_remove(qmp->debugfs_file);
+
 	qmp_qdss_clk_remove(qmp);
 	qmp_cooling_devices_remove(qmp);
 
-- 
2.25.1