[PATCH ath-next v3 4/8] wifi: ath12k: add device DP stats reset support via debugfs

[Pardeep Kaur]

From: Hariharan Ramanathan <hariharan.ramanathan at oss.qualcomm.com>

There is no way to reset device DP stats counters without reloading
the driver, making it difficult to isolate issues to a specific time
window during debugging.

Add a write handler to the device_dp_stats debugfs file so that
writing 'reset' clears all device DP stats counters. Change the file
mode from 0400 to 0600 to allow write access. Use
simple_write_to_buffer() to correctly handle partial writes and
non-zero ppos, consistent with ath12k_write_simulate_fw_crash() in
the same file. Return -EINVAL on unrecognised input.

No lock is taken around the memset since the counters are updated
locklessly in the datapath; taking dp_lock would be misleading as it
does not protect device_stats updates.

Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.6.r1-00402-QCAHKSWPL_SILICONZ-1

Signed-off-by: Hariharan Ramanathan <hariharan.ramanathan at oss.qualcomm.com>
Co-developed-by: Pardeep Kaur <pardeep.kaur at oss.qualcomm.com>
Signed-off-by: Pardeep Kaur <pardeep.kaur at oss.qualcomm.com>
---
 drivers/net/wireless/ath/ath12k/debugfs.c | 36 ++++++++++++++++++++++-
 1 file changed, 35 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath12k/debugfs.c b/drivers/net/wireless/ath/ath12k/debugfs.c
index ec49692107a8..cbda754d8656 100644
--- a/drivers/net/wireless/ath/ath12k/debugfs.c
+++ b/drivers/net/wireless/ath/ath12k/debugfs.c
@@ -1220,8 +1220,42 @@ static ssize_t ath12k_debugfs_dump_device_dp_stats(struct file *file,
 	return ret;
 }
 
+static ssize_t
+ath12k_debugfs_write_device_dp_stats(struct file *file,
+				     const char __user *user_buf,
+				     size_t count, loff_t *ppos)
+{
+	struct ath12k_base *ab = file->private_data;
+	struct ath12k_dp *dp = ath12k_ab_to_dp(ab);
+	struct ath12k_device_dp_stats *device_stats = &dp->device_stats;
+	char buf[20] = {};
+	int ret;
+
+	/* filter partial writes and invalid commands */
+	if (*ppos != 0 || count >= sizeof(buf) || count == 0)
+		return -EINVAL;
+
+	ret = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, user_buf, count);
+	if (ret < 0)
+		return ret;
+
+	/* drop the possible '\n' from the end */
+	if (buf[*ppos - 1] == '\n')
+		buf[*ppos - 1] = '\0';
+
+	if (!strcmp(buf, "reset")) {
+		memset(device_stats, 0, sizeof(*device_stats));
+		return count;
+	}
+
+	ath12k_warn(ab, "unsupported command: %s\n", buf);
+
+	return -EINVAL;
+}
+
 static const struct file_operations fops_device_dp_stats = {
 	.read = ath12k_debugfs_dump_device_dp_stats,
+	.write = ath12k_debugfs_write_device_dp_stats,
 	.open = simple_open,
 	.owner = THIS_MODULE,
 	.llseek = default_llseek,
@@ -1232,7 +1266,7 @@ void ath12k_debugfs_pdev_create(struct ath12k_base *ab)
 	debugfs_create_file("simulate_fw_crash", 0600, ab->debugfs_soc, ab,
 			    &fops_simulate_fw_crash);
 
-	debugfs_create_file("device_dp_stats", 0400, ab->debugfs_soc, ab,
+	debugfs_create_file("device_dp_stats", 0600, ab->debugfs_soc, ab,
 			    &fops_device_dp_stats);
 }
 
-- 
2.34.1