[PATCH ath-next v2 4/8] wifi: ath12k: add device DP stats reset support via debugfs

[Pardeep Kaur <pardeep.kaur@oss.qualcomm.com>]

From: Hariharan Ramanathan <hariharan.ramanathan@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 strcmp() with
newline stripping to match the input, consistent with the existing
pattern in debugfs.c. 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@oss.qualcomm.com>
Co-developed-by: Pardeep Kaur <pardeep.kaur@oss.qualcomm.com>
Signed-off-by: Pardeep Kaur <pardeep.kaur@oss.qualcomm.com>
---
 drivers/net/wireless/ath/ath12k/debugfs.c | 35 ++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath12k/debugfs.c b/drivers/net/wireless/ath/ath12k/debugfs.c
index ec49692107a8..0e446a666f4c 100644
--- a/drivers/net/wireless/ath/ath12k/debugfs.c
+++ b/drivers/net/wireless/ath/ath12k/debugfs.c
@@ -1220,8 +1220,41 @@ 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;
+
+	if (count >= sizeof(buf))
+		return -EINVAL;
+
+	ret = copy_from_user(buf, user_buf, count);
+	if (ret)
+		return -EFAULT;
+
+	/* drop the possible '\n' from the end */
+	if (count > 0 && buf[count - 1] == '\n')
+		buf[count - 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 +1265,7 @@ 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