linux-kernel - [PATCH] mmc: atmel-mci: Add error injection via debugfs

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Date:   Sun,  2 Feb 2020 16:00:48 +0100
From:   Jonas Danielsson <jonas@...ital-systems.com>
To:     linux-mmc@...r.kernel.org
Cc:     jonas@...ital-systems.com,
        Ludovic Desroches <ludovic.desroches@...rochip.com>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] mmc: atmel-mci: Add error injection via debugfs

From: Jonas Danielsson <jonas@...ital-systems.com>

This functionality was useful for us while debugging issues with
a vendor wifi-driver that misbehaved on the SDIO bus.

This will allow you to check how SDIO clients handle mmc
command and data errors.

Signed-off-by: Jonas Danielsson <jonas@...ital-systems.com>
---
 drivers/mmc/host/atmel-mci.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index a9dad641c..11289c8e5 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -328,6 +328,8 @@ struct atmel_mci {
 	u32			data_status;
 	u32			stop_cmdr;
 
+	bool force_cmd_error;
+	bool force_data_error;
 	struct tasklet_struct	tasklet;
 	unsigned long		pending_events;
 	unsigned long		completed_events;
@@ -618,6 +620,14 @@ static void atmci_init_debugfs(struct atmel_mci_slot *slot)
 	if (!node)
 		goto err;
 
+	node = debugfs_create_bool("force_cmd_error", 644, root, &host->force_cmd_error);
+	if (!node)
+		goto err;
+
+	node = debugfs_create_bool("force_data_error", 644, root, &host->force_data_error);
+	if (!node)
+		goto err;
+
 	node = debugfs_create_u32("state", S_IRUSR, root, (u32 *)&host->state);
 	if (!node)
 		goto err;
@@ -1807,7 +1817,12 @@ static void atmci_tasklet_func(unsigned long priv)
 				 * If there is a command error don't start
 				 * data transfer.
 				 */
-				if (mrq->cmd->error) {
+				if (mrq->cmd->error || host->force_cmd_error) {
+					if (host->force_cmd_error) {
+						dev_info(&host->pdev->dev, "FSM: forced cmd error!\n");
+						host->force_cmd_error = false;
+						mrq->cmd->error = -EINVAL;
+					}
 					host->stop_transfer(host);
 					host->data = NULL;
 					atmci_writel(host, ATMCI_IDR,
@@ -1939,7 +1954,11 @@ static void atmci_tasklet_func(unsigned long priv)
 			atmci_writel(host, ATMCI_IDR, ATMCI_TXRDY | ATMCI_RXRDY
 			                   | ATMCI_DATA_ERROR_FLAGS);
 			status = host->data_status;
-			if (unlikely(status)) {
+			if (unlikely(status) || host->force_data_error) {
+				if (data && host->force_data_error) {
+					dev_info(&host->pdev->dev, "FSM: forced data error!\n");
+					host->force_data_error = false;
+				}
 				host->stop_transfer(host);
 				host->data = NULL;
 				if (data) {
@@ -2519,6 +2538,7 @@ static int atmci_probe(struct platform_device *pdev)
 		return -ENOMEM;
 
 	host->pdev = pdev;
+	host->force_data_error = host->force_cmd_error = false;
 	spin_lock_init(&host->lock);
 	INIT_LIST_HEAD(&host->queue);
 
-- 
2.23.0