mmc: sdhci-pci-gli: Enable short circuit protection mechanism of GL9755

Short circuit protection mechanism of GL9755 is disabled by HW default
setting. Enable short circuit protection to prevent GL9755 from being
damaged by short circuit or over current.

Signed-off-by: Renius Chen <reniuschengl@gmail.com>
Link: https://lore.kernel.org/r/20210225111307.62975-1-reniuschengl@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/sdhci-pci-gli.c

@@ -123,6 +123,9 @@
 #define PCI_GLI_9755_PLLSSC        0x68
 #define   PCI_GLI_9755_PLLSSC_PPM    GENMASK(15, 0)
 
+#define PCI_GLI_9755_SerDes  0x70
+#define PCI_GLI_9755_SCP_DIS   BIT(19)
+
 #define GLI_MAX_TUNING_LOOP 40
 
 /* Genesys Logic chipset */
@@ -547,6 +550,11 @@ static void gl9755_hw_setting(struct sdhci_pci_slot *slot)
 	value &= ~PCI_GLI_9755_DMACLK;
 	pci_write_config_dword(pdev, PCI_GLI_9755_PECONF, value);
 
+	/* enable short circuit protection */
+	pci_read_config_dword(pdev, PCI_GLI_9755_SerDes, &value);
+	value &= ~PCI_GLI_9755_SCP_DIS;
+	pci_write_config_dword(pdev, PCI_GLI_9755_SerDes, value);
+
 	gl9755_wt_off(pdev);
 }