misc: rtsx: usb card reader: add OCP support

This patch adds support for Over Current Protection (OCP) to the Realtek
USB card reader driver.

The OCP mechanism protects the hardware by detecting and handling current
overload conditions.
This implementation includes:

- Register configurations to enable OCP monitoring.
- Handling of OCP interrupt events and associated error reporting.
- Card power management changes in response to OCP triggers.

This enhancement improves the robustness of the driver when operating in
environments where electrical anomalies may occur, particularly with SD
and MS card interfaces.

Signed-off-by: Ricky Wu <ricky_wu@realtek.com>
Link: https://lore.kernel.org/r/20250812030811.2426112-1-ricky_wu@realtek.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 30 insertions, 3 deletions

diff --git a/drivers/mmc/host/rtsx_usb_sdmmc.c b/drivers/mmc/host/rtsx_usb_sdmmc.c
index c5f6b9df066b..e1ed39c657c3 100644
--- a/drivers/mmc/host/rtsx_usb_sdmmc.c
+++ b/drivers/mmc/host/rtsx_usb_sdmmc.c
@@ -48,7 +48,7 @@ struct rtsx_usb_sdmmc {
 	bool			ddr_mode;
 
 	unsigned char		power_mode;
-
+	u16			ocp_stat;
 #ifdef RTSX_USB_USE_LEDS_CLASS
 	struct led_classdev	led;
 	char			led_name[32];
@@ -785,6 +785,9 @@ static int sdmmc_get_cd(struct mmc_host *mmc)
 
 	mutex_unlock(&ucr->dev_mutex);
 
+	/* get OCP status */
+	host->ocp_stat = (val >> 4) & 0x03;
+
 	/* Treat failed detection as non-exist */
 	if (err)
 		goto no_card;
@@ -795,6 +798,11 @@ static int sdmmc_get_cd(struct mmc_host *mmc)
 	}
 
 no_card:
+	/* clear OCP status */
+	if (host->ocp_stat & (MS_OCP_NOW | MS_OCP_EVER)) {
+		rtsx_usb_write_register(ucr, OCPCTL, MS_OCP_CLEAR, MS_OCP_CLEAR);
+		host->ocp_stat = 0;
+	}
 	host->card_exist = false;
 	return 0;
 }
@@ -818,7 +826,11 @@ static void sdmmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
 		cmd->error = -ENOMEDIUM;
 		goto finish_detect_card;
 	}
-
+	/* check OCP stat */
+	if (host->ocp_stat & (MS_OCP_NOW | MS_OCP_EVER)) {
+		cmd->error = -ENOMEDIUM;
+		goto finish_detect_card;
+	}
 	mutex_lock(&ucr->dev_mutex);
 
 	mutex_lock(&host->host_mutex);
@@ -952,6 +964,10 @@ static int sd_power_on(struct rtsx_usb_sdmmc *host)
 	struct rtsx_ucr *ucr = host->ucr;
 	int err;
 
+	if (host->ocp_stat & (MS_OCP_NOW | MS_OCP_EVER)) {
+		dev_dbg(sdmmc_dev(host), "over current\n");
+		return -EIO;
+	}
 	dev_dbg(sdmmc_dev(host), "%s\n", __func__);
 	rtsx_usb_init_cmd(ucr);
 	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, CARD_SELECT, 0x07, SD_MOD_SEL);
@@ -978,8 +994,18 @@ static int sd_power_on(struct rtsx_usb_sdmmc *host)
 	usleep_range(800, 1000);
 
 	rtsx_usb_init_cmd(ucr);
+	/* WA OCP issue: after OCP, there were problems with reopen card power */
+	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, CARD_PWR_CTL, POWER_MASK, POWER_ON);
+	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, FPDCTL, SSC_POWER_MASK, SSC_POWER_DOWN);
+	err = rtsx_usb_send_cmd(ucr, MODE_C, 100);
+	if (err)
+		return err;
+	msleep(20);
+	rtsx_usb_write_register(ucr, FPDCTL, SSC_POWER_MASK, SSC_POWER_ON);
+	usleep_range(180, 200);
+	rtsx_usb_init_cmd(ucr);
 	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, CARD_PWR_CTL,
-			POWER_MASK|LDO3318_PWR_MASK, POWER_ON|LDO_ON);
+			LDO3318_PWR_MASK, LDO_ON);
 	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, CARD_OE,
 			SD_OUTPUT_EN, SD_OUTPUT_EN);
 
@@ -1332,6 +1358,7 @@ static void rtsx_usb_init_host(struct rtsx_usb_sdmmc *host)
 	mmc->max_req_size = 524288;
 
 	host->power_mode = MMC_POWER_OFF;
+	host->ocp_stat = 0;
 }
 
 static int rtsx_usb_sdmmc_drv_probe(struct platform_device *pdev)