[PATCH 4/5] mmc: mtk-sd: enable internal card-detect logic.

[NeilBrown]

The mtk-sd silicon has integrated card-detect logic that is
enabled, at least, on the MT7621 as used in the GNUBEE NAS.

If the sdhci isn't marked non-removable and doesn't have a
cd-gpio configured, assume the internal cd logic should be used.

Signed-off-by: NeilBrown <n...@brown.name>
---
 drivers/mmc/host/mtk-sd.c |   58 ++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 54 insertions(+), 4 deletions(-)

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index d379f2ece305..341cf5f03429 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -300,6 +300,8 @@
 #define CMD_TIMEOUT         (HZ/10 * 5)        /* 100ms x5 */
 #define DAT_TIMEOUT         (HZ    * 5)        /* 1000ms x5 */
 
+#define DEFAULT_DEBOUNCE       (8)     /* 8 cycles CD debounce */
+
 #define PAD_DELAY_MAX  32 /* PAD delay cells */
 /*--------------------------------------------------------------------------*/
 /* Descriptor Structure                                                     */
@@ -430,6 +432,7 @@ struct msdc_host {
        bool hs400_cmd_resp_sel_rising;
                                 /* cmd response sample selection for HS400 */
        bool hs400_mode;        /* current eMMC will run at hs400 mode */
+       bool internal_cd;       /* Use internal card-detect logic */
        struct msdc_save_para save_para; /* used when gate HCLK */
        struct msdc_tune_para def_tune_para; /* default tune setting */
        struct msdc_tune_para saved_tune_para; /* tune result of CMD21/CMD19 */
@@ -1430,6 +1433,11 @@ static irqreturn_t msdc_irq(int irq, void *dev_id)
                        sdio_signal_irq(host->mmc);
                }
 
+               if ((events & event_mask) & MSDC_INT_CDSC) {
+                       mmc_detect_change(host->mmc, msecs_to_jiffies(20));
+                       events &= ~MSDC_INT_CDSC;
+               }
+
                if (!(events & (event_mask & ~MSDC_INT_SDIOIRQ)))
                        break;
 
@@ -1463,14 +1471,24 @@ static void msdc_init_hw(struct msdc_host *host)
        /* Reset */
        msdc_reset_hw(host);
 
-       /* Disable card detection */
-       sdr_clr_bits(host->base + MSDC_PS, MSDC_PS_CDEN);
-
        /* Disable and clear all interrupts */
        writel(0, host->base + MSDC_INTEN);
        val = readl(host->base + MSDC_INT);
        writel(val, host->base + MSDC_INT);
 
+       /* Configure card detection */
+       if (host->internal_cd) {
+               sdr_set_field(host->base + MSDC_PS, MSDC_PS_CDDEBOUNCE,
+                             DEFAULT_DEBOUNCE);
+               sdr_set_bits(host->base + MSDC_PS, MSDC_PS_CDEN);
+               sdr_set_bits(host->base + MSDC_INTEN, MSDC_INTEN_CDSC);
+               sdr_set_bits(host->base + SDC_CFG, SDC_CFG_INSWKUP);
+       } else {
+               sdr_clr_bits(host->base + SDC_CFG, SDC_CFG_INSWKUP);
+               sdr_clr_bits(host->base + MSDC_PS, MSDC_PS_CDEN);
+               sdr_clr_bits(host->base + MSDC_INTEN, MSDC_INTEN_CDSC);
+       }
+
        if (host->top_base) {
                writel(0, host->top_base + EMMC_TOP_CONTROL);
                writel(0, host->top_base + EMMC_TOP_CMD);
@@ -1580,6 +1598,11 @@ static void msdc_init_hw(struct msdc_host *host)
 static void msdc_deinit_hw(struct msdc_host *host)
 {
        u32 val;
+
+       /* Disabled card-detect */
+       sdr_clr_bits(host->base + MSDC_PS, MSDC_PS_CDEN);
+       sdr_clr_bits(host->base + SDC_CFG, SDC_CFG_INSWKUP);
+
        /* Disable and clear all interrupts */
        writel(0, host->base + MSDC_INTEN);
 
@@ -2078,13 +2101,31 @@ static void msdc_ack_sdio_irq(struct mmc_host *mmc)
        __msdc_enable_sdio_irq(mmc, 1);
 }
 
+static int msdc_get_cd(struct mmc_host *mmc)
+{
+       struct msdc_host *host = mmc_priv(mmc);
+       int val;
+
+       if (mmc->caps & MMC_CAP_NONREMOVABLE)
+               return 1;
+
+       if (!host->internal_cd)
+               return mmc_gpio_get_cd(mmc);
+
+       val = readl(host->base + MSDC_PS) & MSDC_PS_CDSTS;
+       if (mmc->caps2 & MMC_CAP2_CD_ACTIVE_HIGH)
+               return !!val;
+       else
+               return !val;
+}
+
 static const struct mmc_host_ops mt_msdc_ops = {
        .post_req = msdc_post_req,
        .pre_req = msdc_pre_req,
        .request = msdc_ops_request,
        .set_ios = msdc_ops_set_ios,
        .get_ro = mmc_gpio_get_ro,
-       .get_cd = mmc_gpio_get_cd,
+       .get_cd = msdc_get_cd,
        .enable_sdio_irq = msdc_enable_sdio_irq,
        .ack_sdio_irq = msdc_ack_sdio_irq,
        .start_signal_voltage_switch = msdc_ops_switch_volt,
@@ -2206,6 +2247,15 @@ static int msdc_drv_probe(struct platform_device *pdev)
                goto host_free;
        }
 
+       if (!(mmc->caps & MMC_CAP_NONREMOVABLE) &&
+           !mmc_can_gpio_cd(mmc)) {
+               /*
+                * Is removable but no GPIO declared, so
+                * use internal functionality.
+                */
+               host->internal_cd = true;
+       }
+
        msdc_of_property_parse(pdev, host);
 
        host->dev = &pdev->dev;