[PATCH] misc: rtsx: usb card reader: add OCP support

[Ricky Wu <ricky_wu@realtek.com>]

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>
---
 drivers/memstick/host/rtsx_usb_ms.c |  5 ++++-
 drivers/misc/cardreader/rtsx_usb.c  |  7 +++++++
 drivers/mmc/host/rtsx_usb_sdmmc.c   | 32 +++++++++++++++++++++++++----
 include/linux/rtsx_usb.h            | 11 ++++++++++
 4 files changed, 50 insertions(+), 5 deletions(-)

diff --git a/drivers/memstick/host/rtsx_usb_ms.c b/drivers/memstick/host/rtsx_usb_ms.c
index 3878136227e4..9389e9643c24 100644
--- a/drivers/memstick/host/rtsx_usb_ms.c
+++ b/drivers/memstick/host/rtsx_usb_ms.c
@@ -216,7 +216,10 @@ static int ms_power_off(struct rtsx_usb_ms *host)
 
 	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, CARD_CLK_EN, MS_CLK_EN, 0);
 	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, CARD_OE, MS_OUTPUT_EN, 0);
-
+	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, CARD_PWR_CTL,
+			POWER_MASK, POWER_OFF);
+	rtsx_usb_add_cmd(ucr, WRITE_REG_CMD, CARD_PWR_CTL,
+			POWER_MASK | LDO3318_PWR_MASK, POWER_OFF | LDO_SUSPEND);
 	err = rtsx_usb_send_cmd(ucr, MODE_C, 100);
 	if (err < 0)
 		return err;
diff --git a/drivers/misc/cardreader/rtsx_usb.c b/drivers/misc/cardreader/rtsx_usb.c
index d007a4455ce5..1830e9ed2521 100644
--- a/drivers/misc/cardreader/rtsx_usb.c
+++ b/drivers/misc/cardreader/rtsx_usb.c
@@ -552,6 +552,10 @@ static int rtsx_usb_reset_chip(struct rtsx_ucr *ucr)
 	ret = rtsx_usb_send_cmd(ucr, MODE_C, 100);
 	if (ret)
 		return ret;
+	/* config OCP */
+	rtsx_usb_write_register(ucr, OCPCTL, MS_OCP_DETECT_EN, MS_OCP_DETECT_EN);
+	rtsx_usb_write_register(ucr, OCPPARA1, 0xF0, 0x50);
+	rtsx_usb_write_register(ucr, OCPPARA2, 0x7, 0x3);
 
 	/* config non-crystal mode */
 	rtsx_usb_read_register(ucr, CFG_MODE, &val);
@@ -722,6 +726,9 @@ static int rtsx_usb_suspend(struct usb_interface *intf, pm_message_t message)
 			if (val & (SD_CD | MS_CD)) {
 				device_for_each_child(&intf->dev, NULL, rtsx_usb_resume_child);
 				return -EAGAIN;
+			} else {
+				/* if the card does not exists, clear OCP status */
+				rtsx_usb_write_register(ucr, OCPCTL, MS_OCP_CLEAR, MS_OCP_CLEAR);
 			}
 		} else {
 			/* There is an ongoing operation*/
diff --git a/drivers/mmc/host/rtsx_usb_sdmmc.c b/drivers/mmc/host/rtsx_usb_sdmmc.c
index c5f6b9df066b..0632d294b12f 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);
@@ -977,9 +989,19 @@ 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);
 
@@ -1029,7 +1051,8 @@ static void sd_set_power_mode(struct rtsx_usb_sdmmc *host,
 
 	case MMC_POWER_UP:
 		pm_runtime_get_noresume(sdmmc_dev(host));
-		err = sd_power_on(host);
+		if (!(host->ocp_stat & (MS_OCP_NOW | MS_OCP_EVER)))
+			err = sd_power_on(host);
 		if (err)
 			dev_dbg(sdmmc_dev(host), "power-on (err = %d)\n", err);
 		/* issue the clock signals to card at least 74 clocks */
@@ -1332,6 +1355,7 @@ 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)
diff --git a/include/linux/rtsx_usb.h b/include/linux/rtsx_usb.h
index f267a06c6b1e..276b509c03e3 100644
--- a/include/linux/rtsx_usb.h
+++ b/include/linux/rtsx_usb.h
@@ -99,6 +99,17 @@ extern int rtsx_usb_card_exclusive_check(struct rtsx_ucr *ucr, int card);
 #define CD_MASK		(SD_CD | MS_CD | XD_CD)
 #define SD_WP		0x08
 
+/* OCPCTL */
+#define MS_OCP_DETECT_EN		0x08
+#define	MS_OCP_INT_EN			0x04
+#define	MS_OCP_INT_CLR			0x02
+#define	MS_OCP_CLEAR			0x01
+
+/* OCPSTAT */
+#define MS_OCP_DETECT			0x80
+#define MS_OCP_NOW			0x02
+#define MS_OCP_EVER			0x01
+
 /* reader command field offset & parameters */
 #define READ_REG_CMD		0
 #define WRITE_REG_CMD		1
-- 
2.25.1