mmc: am654_sdhci: Implement workaround for card detect

The 4 bit MMC controllers have an internal debounce for the SDCD line
with a debounce delay of 1 second. Therefore, after clocks to the IP are
enabled, software has to wait for this time before it can power on the
controller.

Add a deferred_probe() callback which polls on sdcd for a maximum of 2 seconds
before switching on power to the controller or (in the case of no card)
returning a ENOMEDIUM. This pushes the 1 second wait time to when the
card is actually needed rather than at every probe() making sure that
users who don't insert an SD card in the slot don't have to wait such a
long time.

Signed-off-by: Faiz Abbas <faiz_abbas@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>

1 files changed, 68 insertions, 41 deletions

diff --git a/drivers/mmc/am654_sdhci.c b/drivers/mmc/am654_sdhci.c
index 92e7100f567..ca76e1f5595 100644
--- a/drivers/mmc/am654_sdhci.c
+++ b/drivers/mmc/am654_sdhci.c
@@ -218,44 +218,6 @@ static int am654_sdhci_set_ios_post(struct sdhci_host *host)
 	return 0;
 }
 
-const struct sdhci_ops am654_sdhci_ops = {
-	.set_ios_post		= &am654_sdhci_set_ios_post,
-	.set_control_reg	= &am654_sdhci_set_control_reg,
-};
-
-const struct am654_driver_data am654_drv_data = {
-	.ops = &am654_sdhci_ops,
-	.flags = IOMUX_PRESENT | FREQSEL_2_BIT | DLL_PRESENT | STRBSEL_4_BIT,
-};
-
-const struct am654_driver_data j721e_8bit_drv_data = {
-	.ops = &am654_sdhci_ops,
-	.flags = DLL_PRESENT,
-};
-
-static int j721e_4bit_sdhci_set_ios_post(struct sdhci_host *host)
-{
-	struct udevice *dev = host->mmc->dev;
-	struct am654_sdhci_plat *plat = dev_get_platdata(dev);
-	u32 otap_del_sel, mask, val;
-
-	otap_del_sel = plat->otap_del_sel[host->mmc->selected_mode];
-	mask = OTAPDLYENA_MASK | OTAPDLYSEL_MASK;
-	val = (1 << OTAPDLYENA_SHIFT) | (otap_del_sel << OTAPDLYSEL_SHIFT);
-	regmap_update_bits(plat->base, PHY_CTRL4, mask, val);
-
-	return 0;
-}
-
-const struct sdhci_ops j721e_4bit_sdhci_ops = {
-	.set_ios_post		= &j721e_4bit_sdhci_set_ios_post,
-};
-
-const struct am654_driver_data j721e_4bit_drv_data = {
-	.ops = &j721e_4bit_sdhci_ops,
-	.flags = IOMUX_PRESENT,
-};
-
 int am654_sdhci_init(struct am654_sdhci_plat *plat)
 {
 	u32 ctl_cfg_2 = 0;
@@ -302,6 +264,73 @@ int am654_sdhci_init(struct am654_sdhci_plat *plat)
 	return 0;
 }
 
+#define MAX_SDCD_DEBOUNCE_TIME 2000
+static int am654_sdhci_deferred_probe(struct sdhci_host *host)
+{
+	struct udevice *dev = host->mmc->dev;
+	struct am654_sdhci_plat *plat = dev_get_platdata(dev);
+	unsigned long start;
+	int val;
+
+	/*
+	 * The controller takes about 1 second to debounce the card detect line
+	 * and doesn't let us power on until that time is up. Instead of waiting
+	 * for 1 second at every stage, poll on the CARD_PRESENT bit upto a
+	 * maximum of 2 seconds to be safe..
+	 */
+	start = get_timer(0);
+	do {
+		if (get_timer(start) > MAX_SDCD_DEBOUNCE_TIME)
+			return -ENOMEDIUM;
+
+		val = mmc_getcd(host->mmc);
+	} while (!val);
+
+	am654_sdhci_init(plat);
+
+	return sdhci_probe(dev);
+}
+
+const struct sdhci_ops am654_sdhci_ops = {
+	.deferred_probe		= am654_sdhci_deferred_probe,
+	.set_ios_post		= &am654_sdhci_set_ios_post,
+	.set_control_reg	= &am654_sdhci_set_control_reg,
+};
+
+const struct am654_driver_data am654_drv_data = {
+	.ops = &am654_sdhci_ops,
+	.flags = IOMUX_PRESENT | FREQSEL_2_BIT | DLL_PRESENT | STRBSEL_4_BIT,
+};
+
+const struct am654_driver_data j721e_8bit_drv_data = {
+	.ops = &am654_sdhci_ops,
+	.flags = DLL_PRESENT,
+};
+
+static int j721e_4bit_sdhci_set_ios_post(struct sdhci_host *host)
+{
+	struct udevice *dev = host->mmc->dev;
+	struct am654_sdhci_plat *plat = dev_get_platdata(dev);
+	u32 otap_del_sel, mask, val;
+
+	otap_del_sel = plat->otap_del_sel[host->mmc->selected_mode];
+	mask = OTAPDLYENA_MASK | OTAPDLYSEL_MASK;
+	val = (1 << OTAPDLYENA_SHIFT) | (otap_del_sel << OTAPDLYSEL_SHIFT);
+	regmap_update_bits(plat->base, PHY_CTRL4, mask, val);
+
+	return 0;
+}
+
+const struct sdhci_ops j721e_4bit_sdhci_ops = {
+	.deferred_probe		= am654_sdhci_deferred_probe,
+	.set_ios_post		= &j721e_4bit_sdhci_set_ios_post,
+};
+
+const struct am654_driver_data j721e_4bit_drv_data = {
+	.ops = &j721e_4bit_sdhci_ops,
+	.flags = IOMUX_PRESENT,
+};
+
 static int sdhci_am654_get_otap_delay(struct udevice *dev,
 				      struct mmc_config *cfg)
 {
@@ -375,9 +404,7 @@ static int am654_sdhci_probe(struct udevice *dev)
 
 	regmap_init_mem_index(dev_ofnode(dev), &plat->base, 1);
 
-	am654_sdhci_init(plat);
-
-	return sdhci_probe(dev);
+	return 0;
 }
 
 static int am654_sdhci_ofdata_to_platdata(struct udevice *dev)