mmc: sdhci-msm: Configuring IO_PAD support for sdhci-msm

From the HPG:

During probe check whether the vdd-io regulator of sdhc platform device can support 1.8V and 3V and store this information as a capability of platform device.

Signed-off-by Vijay Viswanath <[email protected]>

Reviewed-by Douglas Anderson <[email protected]>

---
 drivers/mmc/host/sdhci-msm.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

drivers/mmc/host/sdhci-msm.c +28 -1

index c283291..edd30a2 100644
@@ -21,6 +21,7 @@
 #include <linux/pm_runtime.h>
 #include <linux/slab.h>
 #include <linux/iopoll.h>
+#include <linux/regulator/consumer.h>
 
 #include "sdhci-pltfm.h"
 

@@ -81,6 +82,9 @@
 #define CORE_HC_SELECT_IN_HS400	(6 << 19)
 #define CORE_HC_SELECT_IN_MASK	(7 << 19)
 
+#define CORE_3_0V_SUPPORT	(1 << 25)
+#define CORE_1_8V_SUPPORT	(1 << 26)
+
 #define CORE_CSR_CDC_CTLR_CFG0		0x130
 #define CORE_SW_TRIG_FULL_CALIB		BIT(16)
 #define CORE_HW_AUTOCAL_ENA		BIT(17)

@@ -148,6 +152,7 @@ struct sdhci_msm_host {
 	u32 curr_io_level;
 	wait_queue_head_t pwr_irq_wait;
 	bool pwr_irq_flag;
+	u32 caps_0;
 };
 
 static unsigned int msm_get_clock_rate_for_bus_mode(struct sdhci_host *host,

@@ -1103,7 +1108,7 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
 	struct sdhci_msm_host *msm_host = sdhci_pltfm_priv(pltfm_host);
 	u32 irq_status, irq_ack = 0;
 	int retry = 10;
-	int pwr_state = 0, io_level = 0;
+	u32 pwr_state = 0, io_level = 0;
 
 
 	irq_status = readl_relaxed(msm_host->core_mem + CORE_PWRCTL_STATUS);

@@ -1313,6 +1318,27 @@ static void sdhci_msm_writeb(struct sdhci_host *host, u8 val, int reg)
 		sdhci_msm_check_power_status(host, req_type);
 }
 
+static void sdhci_msm_set_regulator_caps(struct sdhci_msm_host *msm_host)
+{
+	struct mmc_host *mmc = msm_host->mmc;
+	struct regulator *supply = mmc->supply.vqmmc;
+	u32 caps = 0;
+
+	if (!IS_ERR(mmc->supply.vqmmc)) {
+		if (regulator_is_supported_voltage(supply, 1700000, 1950000))
+			caps |= CORE_1_8V_SUPPORT;
+		if (regulator_is_supported_voltage(supply, 2700000, 3600000))
+			caps |= CORE_3_0V_SUPPORT;
+
+		if (!caps)
+			pr_warn("%s: 1.8/3V not supported for vqmmc\n",
+					mmc_hostname(mmc));
+	}
+
+	msm_host->caps_0 |= caps;
+	pr_debug("%s: supported caps: 0x%08x\n", mmc_hostname(mmc), caps);
+}
+
 static const struct of_device_id sdhci_msm_dt_match[] = {
 	{ .compatible = "qcom,sdhci-msm-v4" },
 	{},

@@ -1530,6 +1556,7 @@ static int sdhci_msm_probe(struct platform_device *pdev)
 	ret = sdhci_add_host(host);
 	if (ret)
 		goto pm_runtime_disable;
+	sdhci_msm_set_regulator_caps(msm_host);
 
 	pm_runtime_mark_last_busy(&pdev->dev);
 	pm_runtime_put_autosuspend(&pdev->dev);

Signature · 2 lines

 Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

The PADs for SD card are dual-voltage that support 3v/1.8v. Those PADs have a control signal (io_pad_pwr_switch/mode18 ) that indicates whether the PAD works in 3v or 1.8v.

SDHC core on msm platforms should have IO_PAD_PWR_SWITCH bit set/unset based on actual voltage used for IO lines. So when power irq is triggered for io high or io low, the driver should check the voltages supported and set the pad accordingly.

Signed-off-by Krishna Konda <[email protected]>

Signed-off-by Venkat Gopalakrishnan <[email protected]>

Signed-off-by Vijay Viswanath <[email protected]>

Reviewed-by Douglas Anderson <[email protected]>

---
 drivers/mmc/host/sdhci-msm.c | 57 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 55 insertions(+), 2 deletions(-)

drivers/mmc/host/sdhci-msm.c +55 -2

index edd30a2..bb11916 100644
@@ -78,12 +78,15 @@
 #define CORE_HC_MCLK_SEL_DFLT	(2 << 8)
 #define CORE_HC_MCLK_SEL_HS400	(3 << 8)
 #define CORE_HC_MCLK_SEL_MASK	(3 << 8)
+#define CORE_IO_PAD_PWR_SWITCH_EN	(1 << 15)
+#define CORE_IO_PAD_PWR_SWITCH  (1 << 16)
 #define CORE_HC_SELECT_IN_EN	BIT(18)
 #define CORE_HC_SELECT_IN_HS400	(6 << 19)
 #define CORE_HC_SELECT_IN_MASK	(7 << 19)
 
 #define CORE_3_0V_SUPPORT	(1 << 25)
 #define CORE_1_8V_SUPPORT	(1 << 26)
+#define CORE_VOLT_SUPPORT	(CORE_3_0V_SUPPORT | CORE_1_8V_SUPPORT)
 
 #define CORE_CSR_CDC_CTLR_CFG0		0x130
 #define CORE_SW_TRIG_FULL_CALIB		BIT(16)

@@ -1109,7 +1112,7 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
 	u32 irq_status, irq_ack = 0;
 	int retry = 10;
 	u32 pwr_state = 0, io_level = 0;
-
+	u32 config;
 
 	irq_status = readl_relaxed(msm_host->core_mem + CORE_PWRCTL_STATUS);
 	irq_status &= INT_MASK;

@@ -1166,6 +1169,38 @@ static void sdhci_msm_handle_pwr_irq(struct sdhci_host *host, int irq)
 	 */
 	writel_relaxed(irq_ack, msm_host->core_mem + CORE_PWRCTL_CTL);
 
+	/*
+	 * If we don't have info regarding the voltage levels supported by
+	 * regulators, don't change the IO PAD PWR SWITCH.
+	 */
+	if (msm_host->caps_0 & CORE_VOLT_SUPPORT) {
+		u32 new_config;
+		/*
+		 * We should unset IO PAD PWR switch only if the register write
+		 * can set IO lines high and the regulator also switches to 3 V.
+		 * Else, we should keep the IO PAD PWR switch set.
+		 * This is applicable to certain targets where eMMC vccq supply
+		 * is only 1.8V. In such targets, even during REQ_IO_HIGH, the
+		 * IO PAD PWR switch must be kept set to reflect actual
+		 * regulator voltage. This way, during initialization of
+		 * controllers with only 1.8V, we will set the IO PAD bit
+		 * without waiting for a REQ_IO_LOW.
+		 */
+		config = readl_relaxed(host->ioaddr + CORE_VENDOR_SPEC);
+		new_config = config;
+
+		if ((io_level & REQ_IO_HIGH) &&
+				(msm_host->caps_0 & CORE_3_0V_SUPPORT))
+			new_config &= ~CORE_IO_PAD_PWR_SWITCH;
+		else if ((io_level & REQ_IO_LOW) ||
+				(msm_host->caps_0 & CORE_1_8V_SUPPORT))
+			new_config |= CORE_IO_PAD_PWR_SWITCH;
+
+		if (config ^ new_config)
+			writel_relaxed(new_config,
+					host->ioaddr + CORE_VENDOR_SPEC);
+	}
+
 	if (pwr_state)
 		msm_host->curr_pwr_state = pwr_state;
 	if (io_level)

@@ -1322,7 +1357,8 @@ static void sdhci_msm_set_regulator_caps(struct sdhci_msm_host *msm_host)
 {
 	struct mmc_host *mmc = msm_host->mmc;
 	struct regulator *supply = mmc->supply.vqmmc;
-	u32 caps = 0;
+	u32 caps = 0, config;
+	struct sdhci_host *host = mmc_priv(mmc);
 
 	if (!IS_ERR(mmc->supply.vqmmc)) {
 		if (regulator_is_supported_voltage(supply, 1700000, 1950000))

@@ -1335,6 +1371,23 @@ static void sdhci_msm_set_regulator_caps(struct sdhci_msm_host *msm_host)
 					mmc_hostname(mmc));
 	}
 
+	if (caps) {
+		/*
+		 * Set the PAD_PWR_SWITCH_EN bit so that the PAD_PWR_SWITCH
+		 * bit can be used as required later on.
+		 */
+		u32 io_level = msm_host->curr_io_level;
+
+		config = readl_relaxed(host->ioaddr + CORE_VENDOR_SPEC);
+		config |= CORE_IO_PAD_PWR_SWITCH_EN;
+
+		if ((io_level & REQ_IO_HIGH) && (caps &	CORE_3_0V_SUPPORT))
+			config &= ~CORE_IO_PAD_PWR_SWITCH;
+		else if ((io_level & REQ_IO_LOW) || (caps & CORE_1_8V_SUPPORT))
+			config |= CORE_IO_PAD_PWR_SWITCH;
+
+		writel_relaxed(config, host->ioaddr + CORE_VENDOR_SPEC);
+	}
 	msm_host->caps_0 |= caps;
 	pr_debug("%s: supported caps: 0x%08x\n", mmc_hostname(mmc), caps);
 }

Signature · 2 lines

 Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc. 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

From the HPG:
In some platform, SDCC controller can be connected to either an eMMC device or an SD card. The PADs for SD card are dual-voltage that support 3v/1.8v. Those PADs have a control signal (io_pad_pwr_switch/mode18 ) that indicates whether the PAD works in 3v or 1.8v.

For SD usage the default value of this signal is ‘0’, and SD driver changes it to ‘1’ as a part of voltage switching sequence.
For eMMC usage, SW should configure this signal to ‘1’ and supply 1.8v to PADs before starting any activity on the eMMC BUS.

To set this signal, write the following in the
SDC1_SDCC_HC_VENDOR_SPECIFIC_FUNC register:
HC_IO_PAD_PWR_SWITCH: bit 16
HC_IO_PAD_PWR_SWITCH_EN: bit 15

Changes since v1:
Modified comments on io_pad related changes. Split some read+modify+write commands to multiple lines

Changes since v2:
IO_PAD_PWR_SWITCH_EN will be set only if we have info regarding what voltage is supported by the regulators.
Replaced regulator_list_voltage() API with regulator_is_supported_voltage().

Changes since v3:
Removed unnecessary prints and extra lines.

Changes since v4:
Removed unnecessary mb() within sdhci_msm_handle_pwr_irq() since wakeup calls have implicit write barriers.

Krishna Konda (1):
mmc: sdhci-msm: support voltage pad switching

Vijay Viswanath (1):
mmc: sdhci-msm: Add support to store supported vdd-io voltages

 drivers/mmc/host/sdhci-msm.c | 99 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 97 insertions(+), 2 deletions(-)

--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.