drivers: mmc: sdhci_am654: Add the quirk to set TESTCD bit

The ARASAN MMC controller on Keystone 3 class of devices need the SDCD
line to be connected for proper functioning. Similar to the issue pointed
out in sdhci-of-arasan.c driver, commit 3794c54 ("mmc:
sdhci-of-arasan: Set controller to test mode when no CD bit").

In cases where this can't be connected, add a quirk to force the
controller into test mode and set the TESTCD bit. Use the flag
"ti,fails-without-test-cd", to implement this above quirk when required.

Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Link: https://lore.kernel.org/r/20220425063120.10135-3-a-govindraju@ti.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: r-vignesh

drivers/mmc/host/sdhci_am654.c

@@ -147,6 +147,9 @@ struct sdhci_am654_data {
 	int drv_strength;
 	int strb_sel;
 	u32 flags;
+	u32 quirks;
+
+#define SDHCI_AM654_QUIRK_FORCE_CDTEST BIT(0)
 };
 
 struct sdhci_am654_driver_data {
@@ -369,6 +372,21 @@ static void sdhci_am654_write_b(struct sdhci_host *host, u8 val, int reg)
 	}
 }
 
+static void sdhci_am654_reset(struct sdhci_host *host, u8 mask)
+{
+	u8 ctrl;
+	struct sdhci_pltfm_host *pltfm_host = sdhci_priv(host);
+	struct sdhci_am654_data *sdhci_am654 = sdhci_pltfm_priv(pltfm_host);
+
+	sdhci_reset(host, mask);
+
+	if (sdhci_am654->quirks & SDHCI_AM654_QUIRK_FORCE_CDTEST) {
+		ctrl = sdhci_readb(host, SDHCI_HOST_CONTROL);
+		ctrl |= SDHCI_CTRL_CDTEST_INS | SDHCI_CTRL_CDTEST_EN;
+		sdhci_writeb(host, ctrl, SDHCI_HOST_CONTROL);
+	}
+}
+
 static int sdhci_am654_execute_tuning(struct mmc_host *mmc, u32 opcode)
 {
 	struct sdhci_host *host = mmc_priv(mmc);
@@ -500,7 +518,7 @@ static struct sdhci_ops sdhci_j721e_4bit_ops = {
 	.set_clock = sdhci_j721e_4bit_set_clock,
 	.write_b = sdhci_am654_write_b,
 	.irq = sdhci_am654_cqhci_irq,
-	.reset = sdhci_reset,
+	.reset = sdhci_am654_reset,
 };
 
 static const struct sdhci_pltfm_data sdhci_j721e_4bit_pdata = {
@@ -719,6 +737,9 @@ static int sdhci_am654_get_of_property(struct platform_device *pdev,
 	device_property_read_u32(dev, "ti,clkbuf-sel",
 				 &sdhci_am654->clkbuf_sel);
 
+	if (device_property_read_bool(dev, "ti,fails-without-test-cd"))
+		sdhci_am654->quirks |= SDHCI_AM654_QUIRK_FORCE_CDTEST;
+
 	sdhci_get_of_property(pdev);
 
 	return 0;