mmc: esdhc-imx: fix card interrupt loss on freescale eSDHC

Apply a workaround for the imx eSDHC controller to avoid missing
card interrupts.  This makes SDIO work.

Signed-off-by: Tony Lin <tony.lin@freescale.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 9ebfb4b..0e9780f 100644 (file)
--- a/drivers/mmc/host/sdhci-esdhc-imx.c
+++ b/drivers/mmc/host/sdhci-esdhc-imx.c
@@ -27,6 +27,7 @@
 #include "sdhci-pltfm.h"
 #include "sdhci-esdhc.h"
 
+#define        SDHCI_CTRL_D3CD                 0x08
 /* VENDOR SPEC register */
 #define SDHCI_VENDOR_SPEC              0xC0
 #define  SDHCI_VENDOR_SPEC_SDIO_QUIRK  0x00000002
@@ -141,13 +142,32 @@ static void esdhc_writel_le(struct sdhci_host *host, u32 val, int reg)
        struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
        struct pltfm_imx_data *imx_data = pltfm_host->priv;
        struct esdhc_platform_data *boarddata = &imx_data->boarddata;
-
-       if (unlikely((reg == SDHCI_INT_ENABLE || reg == SDHCI_SIGNAL_ENABLE)
-                       && (boarddata->cd_type == ESDHC_CD_GPIO)))
-               /*
-                * these interrupts won't work with a custom card_detect gpio
-                */
-               val &= ~(SDHCI_INT_CARD_REMOVE | SDHCI_INT_CARD_INSERT);
+       u32 data;
+
+       if (unlikely(reg == SDHCI_INT_ENABLE || reg == SDHCI_SIGNAL_ENABLE)) {
+               if (boarddata->cd_type == ESDHC_CD_GPIO)
+                       /*
+                        * These interrupts won't work with a custom
+                        * card_detect gpio (only applied to mx25/35)
+                        */
+                       val &= ~(SDHCI_INT_CARD_REMOVE | SDHCI_INT_CARD_INSERT);
+
+               if (val & SDHCI_INT_CARD_INT) {
+                       /*
+                        * Clear and then set D3CD bit to avoid missing the
+                        * card interrupt.  This is a eSDHC controller problem
+                        * so we need to apply the following workaround: clear
+                        * and set D3CD bit will make eSDHC re-sample the card
+                        * interrupt. In case a card interrupt was lost,
+                        * re-sample it by the following steps.
+                        */
+                       data = readl(host->ioaddr + SDHCI_HOST_CONTROL);
+                       data &= ~SDHCI_CTRL_D3CD;
+                       writel(data, host->ioaddr + SDHCI_HOST_CONTROL);
+                       data |= SDHCI_CTRL_D3CD;
+                       writel(data, host->ioaddr + SDHCI_HOST_CONTROL);
+               }
+       }
 
        if (unlikely((imx_data->flags & ESDHC_FLAG_MULTIBLK_NO_INT)
                                && (reg == SDHCI_INT_STATUS)
@@ -217,8 +237,10 @@ static void esdhc_writeb_le(struct sdhci_host *host, u8 val, int reg)
                 */
                return;
        case SDHCI_HOST_CONTROL:
-               /* FSL messed up here, so we can just keep those two */
-               new_val = val & (SDHCI_CTRL_LED | SDHCI_CTRL_4BITBUS);
+               /* FSL messed up here, so we can just keep those three */
+               new_val = val & (SDHCI_CTRL_LED | \
+                               SDHCI_CTRL_4BITBUS | \
+                               SDHCI_CTRL_D3CD);
                /* ensure the endianess */
                new_val |= ESDHC_HOST_CONTROL_LE;
                /* DMA mode bits are shifted */