[PATCH V4 2/2] soc: qcom: aoss: Add debugfs entry

[Deepak Kumar Singh <deesin@xxxxxxxxxxxxxx>]

It can be useful to control the different power states of various
parts of hardware for device testing. Add a debugfs node for qmp so
messages can be sent to aoss for debugging and testing purposes.

Signed-off-by: Chris Lew <clew@xxxxxxxxxxxxxx>
Signed-off-by: Deepak Kumar Singh <deesin@xxxxxxxxxxxxxx>
---
 drivers/soc/qcom/qcom_aoss.c | 39 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/drivers/soc/qcom/qcom_aoss.c b/drivers/soc/qcom/qcom_aoss.c
index cd75d4d..438adc9 100644
--- a/drivers/soc/qcom/qcom_aoss.c
+++ b/drivers/soc/qcom/qcom_aoss.c
@@ -4,6 +4,7 @@
  */
 #include <dt-bindings/power/qcom-aoss-qmp.h>
 #include <linux/clk-provider.h>
+#include <linux/debugfs.h>
 #include <linux/interrupt.h>
 #include <linux/io.h>
 #include <linux/mailbox_client.h>
@@ -89,6 +90,9 @@ struct qmp {
 	struct clk_hw qdss_clk;
 	struct genpd_onecell_data pd_data;
 	struct qmp_cooling_device *cooling_devs;
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+	struct dentry *debugfs_file;
+#endif /* CONFIG_DEBUG_FS */
 };
 
 struct qmp_pd {
@@ -575,6 +579,32 @@ void qmp_put(struct qmp *qmp)
 }
 EXPORT_SYMBOL(qmp_put);
 
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+static ssize_t aoss_dbg_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 len;
+
+	ret  = copy_from_user(buf, userstr, len);
+	if (ret)
+		return len;
+
+	ret = qmp_send(qmp, buf, QMP_MSG_LEN);
+
+	return ret ? ret : len;
+}
+
+static const struct file_operations aoss_dbg_fops = {
+	.open = simple_open,
+	.write = aoss_dbg_write,
+};
+#endif /* CONFIG_DEBUG_FS */
+
 static int qmp_probe(struct platform_device *pdev)
 {
 	struct resource *res;
@@ -632,6 +662,11 @@ static int qmp_probe(struct platform_device *pdev)
 
 	atomic_set(&qmp->orphan, 0);
 
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+	qmp->debugfs_file = debugfs_create_file("aoss_send_message", 0220, NULL,
+						qmp, &aoss_dbg_fops);
+#endif /* CONFIG_DEBUG_FS */
+
 	return 0;
 
 err_remove_qdss_clk:
@@ -649,6 +684,10 @@ static int qmp_remove(struct platform_device *pdev)
 {
 	struct qmp *qmp = platform_get_drvdata(pdev);
 
+#if IS_ENABLED(CONFIG_DEBUG_FS)
+	debugfs_remove(qmp->debugfs_file);
+#endif /* CONFIG_DEBUG_FS */
+
 	qmp_qdss_clk_remove(qmp);
 	qmp_pd_remove(qmp);
 	qmp_cooling_devices_remove(qmp);
-- 
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