mmc: dw_mmc: release hardware lock error

[Dongjin Kim <dongjin.kim@agreeyamobility.net>]

Hello,

I encountered the problem that my hardware is frozen while switching clock from 
400kHz to others. This is caused that hardware locked error was triggered when 
CMD register was written and interrupt was pended. Tested IP version is 2.10a

Cheers,
Dongjin.

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 2f7f5ee..05ccee8 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -520,15 +520,33 @@ static void mci_send_cmd(struct dw_mci_slot *slot, u32 
cmd, u32 arg)
 	struct dw_mci *host = slot->host;
 	unsigned long timeout = jiffies + msecs_to_jiffies(500);
 	unsigned int cmd_status = 0;
+	u32 ctrl;
 
+resend:
 	mci_writel(host, CMDARG, arg);
 	wmb();
 	mci_writel(host, CMD, SDMMC_CMD_START | cmd);
+
 	while (time_before(jiffies, timeout)) {
 		cmd_status = mci_readl(host, CMD);
 		if (!(cmd_status & SDMMC_CMD_START))
 			return;
+
+		if (host->cmd_status & SDMMC_INT_HLE) {
+			dev_err(&slot->mmc->class_dev,
+				"Hardware locked error (cmd %#x arg %#x)\n",
+				cmd, arg);
+
+			ctrl = mci_readl(host, CTRL);
+			ctrl |= SDMMC_CTRL_RESET;
+			mci_writel(host, CTRL, ctrl);
+
+			host->cmd_status &= ~SDMMC_INT_HLE;
+
+			goto resend;
+		}
 	}
+
 	dev_err(&slot->mmc->class_dev,
 		"Timeout sending command (cmd %#x arg %#x status %#x)\n",
 		cmd, arg, cmd_status);
@@ -1429,6 +1447,12 @@ static irqreturn_t dw_mci_interrupt(int irq, void 
*dev_id)
 		if (!pending)
 			break;
 
+		if (pending & SDMMC_INT_HLE) {
+			mci_writel(host, RINTSTS, SDMMC_INT_HLE);
+			host->cmd_status = status;
+			smp_wmb();
+		}
+
 		if (pending & DW_MCI_CMD_ERROR_FLAGS) {
 			mci_writel(host, RINTSTS, DW_MCI_CMD_ERROR_FLAGS);
 			host->cmd_status = status;