mwifiex: add support for SDIO card reset

When command timeout happens due to a bug in firmware/hardware,
the timeout handler just prints some debug information. User is
unable to reload the driver in this case.

Inspired by 9a821f5 "libertas: add sd8686 reset_card support",
this patch adds card reset support for SDIO interface when
command timeout happens. If the SDIO host contoller supports
MMC_POWER_OFF|UP|ON operations, the chip will be reset and the
firmware will be re-downloaded.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/mwifiex/cmdevt.c

@@ -944,6 +944,9 @@ mwifiex_cmd_timeout_func(unsigned long function_context)
 	}
 	if (adapter->hw_status == MWIFIEX_HW_STATUS_INITIALIZING)
 		mwifiex_init_fw_complete(adapter);
+
+	if (adapter->if_ops.card_reset)
+		adapter->if_ops.card_reset(adapter);
 }
 
 /*

drivers/net/wireless/mwifiex/main.h

@@ -600,6 +600,7 @@ struct mwifiex_if_ops {
 	int (*event_complete) (struct mwifiex_adapter *, struct sk_buff *);
 	int (*data_complete) (struct mwifiex_adapter *, struct sk_buff *);
 	int (*dnld_fw) (struct mwifiex_adapter *, struct mwifiex_fw_image *);
+	void (*card_reset) (struct mwifiex_adapter *);
 };
 
 struct mwifiex_adapter {

drivers/net/wireless/mwifiex/sdio.c

@@ -1748,6 +1748,37 @@ mwifiex_update_mp_end_port(struct mwifiex_adapter *adapter, u16 port)
 		port, card->mp_data_port_mask);
 }
 
+static struct mmc_host *reset_host;
+static void sdio_card_reset_worker(struct work_struct *work)
+{
+	/* The actual reset operation must be run outside of driver thread.
+	 * This is because mmc_remove_host() will cause the device to be
+	 * instantly destroyed, and the driver then needs to end its thread,
+	 * leading to a deadlock.
+	 *
+	 * We run it in a totally independent workqueue.
+	 */
+
+	pr_err("Resetting card...\n");
+	mmc_remove_host(reset_host);
+	/* 20ms delay is based on experiment with sdhci controller */
+	mdelay(20);
+	mmc_add_host(reset_host);
+}
+static DECLARE_WORK(card_reset_work, sdio_card_reset_worker);
+
+/* This function resets the card */
+static void mwifiex_sdio_card_reset(struct mwifiex_adapter *adapter)
+{
+	struct sdio_mmc_card *card = adapter->card;
+
+	if (work_pending(&card_reset_work))
+		return;
+
+	reset_host = card->func->card->host;
+	schedule_work(&card_reset_work);
+}
+
 static struct mwifiex_if_ops sdio_ops = {
 	.init_if = mwifiex_init_sdio,
 	.cleanup_if = mwifiex_cleanup_sdio,
@@ -1766,6 +1797,7 @@ static struct mwifiex_if_ops sdio_ops = {
 	.cleanup_mpa_buf = mwifiex_cleanup_mpa_buf,
 	.cmdrsp_complete = mwifiex_sdio_cmdrsp_complete,
 	.event_complete = mwifiex_sdio_event_complete,
+	.card_reset = mwifiex_sdio_card_reset,
 };
 
 /*
@@ -1803,6 +1835,7 @@ mwifiex_sdio_cleanup_module(void)
 	/* Set the flag as user is removing this module. */
 	user_rmmod = 1;
 
+	cancel_work_sync(&card_reset_work);
 	sdio_unregister_driver(&mwifiex_sdio);
 }
 

drivers/net/wireless/mwifiex/sdio.h

@@ -25,6 +25,7 @@
 #include <linux/mmc/sdio_ids.h>
 #include <linux/mmc/sdio_func.h>
 #include <linux/mmc/card.h>
+#include <linux/mmc/host.h>
 
 #include "main.h"