mmc: meson-gx: implement card_busy callback

Implement the card_busy callback to be able to verify that the
card is done dealing with voltage switch, when the support is
added later on.
Reviewed-by: Kevin Hilman <khilman@baylibre.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/meson-gx-mmc.c

@@ -76,6 +76,7 @@
 
 #define SD_EMMC_STATUS 0x48
 #define   STATUS_BUSY BIT(31)
+#define   STATUS_DATI GENMASK(23, 16)
 
 #define SD_EMMC_IRQ_EN 0x4c
 #define   IRQ_RXD_ERR_MASK GENMASK(7, 0)
@@ -902,6 +903,17 @@ static void meson_mmc_cfg_init(struct meson_host *host)
 	writel(cfg, host->regs + SD_EMMC_CFG);
 }
 
+static int meson_mmc_card_busy(struct mmc_host *mmc)
+{
+	struct meson_host *host = mmc_priv(mmc);
+	u32 regval;
+
+	regval = readl(host->regs + SD_EMMC_STATUS);
+
+	/* We are only interrested in lines 0 to 3, so mask the other ones */
+	return !(FIELD_GET(STATUS_DATI, regval) & 0xf);
+}
+
 static const struct mmc_host_ops meson_mmc_ops = {
 	.request	= meson_mmc_request,
 	.set_ios	= meson_mmc_set_ios,
@@ -909,6 +921,7 @@ static const struct mmc_host_ops meson_mmc_ops = {
 	.pre_req	= meson_mmc_pre_req,
 	.post_req	= meson_mmc_post_req,
 	.execute_tuning = meson_mmc_execute_tuning,
+	.card_busy	= meson_mmc_card_busy,
 };
 
 static int meson_mmc_probe(struct platform_device *pdev)