[PATCH 5/5] mmc: mtk-sd: enable internal write-protect logic.

[NeilBrown]

The mtk-sd silicon has integrated write-protect detection logic.

If the sdhci isn't marked no-write-protect and doesn't have a
ro-gpio configured, assume the internal wp logic should be used.

Signed-off-by: NeilBrown <n...@brown.name>
---
 drivers/mmc/host/mtk-sd.c |   30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/host/mtk-sd.c b/drivers/mmc/host/mtk-sd.c
index 341cf5f03429..d63d6b62f49a 100644
--- a/drivers/mmc/host/mtk-sd.c
+++ b/drivers/mmc/host/mtk-sd.c
@@ -433,6 +433,7 @@ struct msdc_host {
                                 /* cmd response sample selection for HS400 */
        bool hs400_mode;        /* current eMMC will run at hs400 mode */
        bool internal_cd;       /* Use internal card-detect logic */
+       bool internal_ro;       /* Use internal write-protect 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 */
@@ -2119,12 +2120,30 @@ static int msdc_get_cd(struct mmc_host *mmc)
                return !val;
 }
 
+static int msdc_get_ro(struct mmc_host *mmc)
+{
+       struct msdc_host *host = mmc_priv(mmc);
+       int val;
+
+       if (mmc->caps2 & MMC_CAP2_NO_WRITE_PROTECT)
+               return 0;
+
+       if (!host->internal_ro)
+               return mmc_gpio_get_ro(mmc);
+
+       val = readl(host->base + MSDC_PS) & MSDC_PS_WP;
+       if (mmc->caps2 & MMC_CAP2_RO_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_ro = msdc_get_ro,
        .get_cd = msdc_get_cd,
        .enable_sdio_irq = msdc_enable_sdio_irq,
        .ack_sdio_irq = msdc_ack_sdio_irq,
@@ -2256,6 +2275,15 @@ static int msdc_drv_probe(struct platform_device *pdev)
                host->internal_cd = true;
        }
 
+       if (!(mmc->caps2 & MMC_CAP2_NO_WRITE_PROTECT) &&
+           !mmc_can_gpio_ro(mmc)) {
+               /*
+                * Has write-protect but no GPIO declared, so
+                * use internal functionality.
+                */
+               host->internal_ro = true;
+       }
+
        msdc_of_property_parse(pdev, host);
 
        host->dev = &pdev->dev;