[PATCH 6/8] mmc: sdhci-pxav2: add SDIO card IRQ workaround for PXA168 V1 controller

[Doug Brown <doug@schmorgal.com>]

The PXA168 has a documented silicon bug that causes SDIO card IRQs to be
missed. Implement the first half of the suggested workaround, which
involves resetting the data port logic and issuing a dummy CMD0 to
restart the clock.

Signed-off-by: Doug Brown <doug@schmorgal.com>
---
 drivers/mmc/host/sdhci-pxav2.c | 36 ++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/mmc/host/sdhci-pxav2.c b/drivers/mmc/host/sdhci-pxav2.c
index 4996d72c6d23..0b9b2e4b2153 100644
--- a/drivers/mmc/host/sdhci-pxav2.c
+++ b/drivers/mmc/host/sdhci-pxav2.c
@@ -20,6 +20,8 @@
 #include <linux/slab.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/mmc/sdio.h>
+#include <linux/mmc/mmc.h>
 
 #include "sdhci.h"
 #include "sdhci-pltfm.h"
@@ -43,6 +45,7 @@
 
 struct sdhci_pxav2_host {
 	struct clk *clk_core;
+	void (*orig_post_req)(struct mmc_host *mmc, struct mmc_request *mrq, int err);
 };
 
 static void pxav2_reset(struct sdhci_host *host, u8 mask)
@@ -96,6 +99,37 @@ static inline u16 pxav1_readw(struct sdhci_host *host, int reg)
 	return readw(host->ioaddr + reg);
 }
 
+static void pxav1_post_req(struct mmc_host *mmc, struct mmc_request *mrq, int err)
+{
+	struct sdhci_host *host = mmc_priv(mmc);
+	struct sdhci_pxav2_host *pxav2_host;
+	struct mmc_command dummy_cmd = {};
+	u16 tmp;
+
+	/* If this is an SDIO command, perform errata workaround for silicon bug. */
+	if (!err && mrq->cmd && !mrq->cmd->error &&
+	    (mrq->cmd->opcode == SD_IO_RW_DIRECT ||
+	    mrq->cmd->opcode == SD_IO_RW_EXTENDED)) {
+		/* Reset data port */
+		tmp = readw(host->ioaddr + SDHCI_TIMEOUT_CONTROL);
+		tmp |= 0x400;
+		writew(tmp, host->ioaddr + SDHCI_TIMEOUT_CONTROL);
+
+		/* Clock is now stopped, so restart it by sending a dummy CMD0. */
+		pxav2_host = sdhci_pltfm_priv(sdhci_priv(host));
+
+		dummy_cmd.opcode = MMC_GO_IDLE_STATE;
+		dummy_cmd.arg = 0;
+		dummy_cmd.flags = MMC_RSP_SPI_R1 | MMC_RSP_NONE | MMC_CMD_BC;
+
+		mmc_wait_for_cmd(host->mmc, &dummy_cmd, 0);
+	}
+
+	/* Pass onto SDHCI host driver now */
+	if (pxav2_host->orig_post_req)
+		pxav2_host->orig_post_req(mmc, mrq, err);
+}
+
 static void pxav2_mmc_set_bus_width(struct sdhci_host *host, int width)
 {
 	u8 ctrl;
@@ -252,6 +286,8 @@ static int sdhci_pxav2_probe(struct platform_device *pdev)
 	if (match && of_device_is_compatible(dev->of_node, "mrvl,pxav1-mmc")) {
 		host->quirks |= SDHCI_QUIRK_NO_BUSY_IRQ | SDHCI_QUIRK_32BIT_DMA_SIZE;
 		host->ops = &pxav1_sdhci_ops;
+		pxav2_host->orig_post_req = host->mmc_host_ops.post_req;
+		host->mmc_host_ops.post_req = pxav1_post_req;
 	} else {
 		host->ops = &pxav2_sdhci_ops;
 	}
-- 
2.34.1