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>

1 files changed, 31 insertions, 9 deletions

diff --git a/drivers/mmc/host/sdhci-esdhc-imx.c b/drivers/mmc/host/sdhci-esdhc-imx.c
index 9ebfb4b482f5..0e9780f5a4a9 100644
--- 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 */