mmc: sd: add support for signal voltage switch procedure

Host Controller v3.00 adds another Capabilities register. Apart
from other things, this new register indicates whether the Host
Controller supports SDR50, SDR104, and DDR50 UHS-I modes. The spec
doesn't mention about explicit support for SDR12 and SDR25 UHS-I
modes, so the Host Controller v3.00 should support them by default.
Also if the controller supports SDR104 mode, it will also support
SDR50 mode as well. So depending on the host support, we set the
corresponding MMC_CAP_* flags. One more new register. Host Control2
is added in v3.00, which is used during Signal Voltage Switch
procedure described below.

Since as per v3.00 spec, UHS-I supported hosts should set S18R
to 1, we set S18R (bit 24) of OCR before sending ACMD41. We also
need to set XPC (bit 28) of OCR in case the host can supply >150mA.
This support is indicated by the Maximum Current Capabilities
register of the Host Controller.

If the response of ACMD41 has both CCS and S18A set, we start the
signal voltage switch procedure, which if successfull, will switch
the card from 3.3V signalling to 1.8V signalling. Signal voltage
switch procedure adds support for a new command CMD11 in the
Physical Layer Spec v3.01. As part of this procedure, we need to
set 1.8V Signalling Enable (bit 3) of Host Control2 register, which
if remains set after 5ms, means the switch to 1.8V signalling is
successfull. Otherwise, we clear bit 24 of OCR and retry the
initialization sequence. When we remove the card, and insert the
same or another card, we need to make sure that we start with 3.3V
signalling voltage. So we call mmc_set_signal_voltage() with
MMC_SIGNAL_VOLTAGE_330 set so that we are back to 3.3V signalling
voltage before we actually start initializing the card.

Tested by Zhangfei Gao with a Toshiba uhs card and general hs card,
on mmp2 in SDMA mode.

Signed-off-by: Arindam Nath <[email protected]>
Reviewed-by: Philip Rakity <[email protected]>
Tested-by: Philip Rakity <[email protected]>
Acked-by: Zhangfei Gao <[email protected]>
Signed-off-by: Chris Ball <[email protected]>

Author: amd-anath

drivers/mmc/core/core.c

@@ -942,6 +942,38 @@ u32 mmc_select_voltage(struct mmc_host *host, u32 ocr)
 	return ocr;
 }
 
+int mmc_set_signal_voltage(struct mmc_host *host, int signal_voltage)
+{
+	struct mmc_command cmd = {0};
+	int err = 0;
+
+	BUG_ON(!host);
+
+	/*
+	 * Send CMD11 only if the request is to switch the card to
+	 * 1.8V signalling.
+	 */
+	if (signal_voltage == MMC_SIGNAL_VOLTAGE_180) {
+		cmd.opcode = SD_SWITCH_VOLTAGE;
+		cmd.arg = 0;
+		cmd.flags = MMC_RSP_R1 | MMC_CMD_AC;
+
+		err = mmc_wait_for_cmd(host, &cmd, 0);
+		if (err)
+			return err;
+
+		if (!mmc_host_is_spi(host) && (cmd.resp[0] & R1_ERROR))
+			return -EIO;
+	}
+
+	host->ios.signal_voltage = signal_voltage;
+
+	if (host->ops->start_signal_voltage_switch)
+		err = host->ops->start_signal_voltage_switch(host, &host->ios);
+
+	return err;
+}
+
 /*
  * Select timing parameters for host.
  */

drivers/mmc/core/core.h

@@ -41,6 +41,7 @@ void mmc_set_bus_width(struct mmc_host *host, unsigned int width);
 void mmc_set_bus_width_ddr(struct mmc_host *host, unsigned int width,
 			   unsigned int ddr);
 u32 mmc_select_voltage(struct mmc_host *host, u32 ocr);
+int mmc_set_signal_voltage(struct mmc_host *host, int signal_voltage);
 void mmc_set_timing(struct mmc_host *host, unsigned int timing);
 
 static inline void mmc_delay(unsigned int ms)

drivers/mmc/core/sd.c

@@ -403,6 +403,7 @@ struct device_type sd_type = {
 int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid)
 {
 	int err;
+	u32 rocr;
 
 	/*
 	 * Since we're changing the OCR value, we seem to
@@ -420,12 +421,38 @@ int mmc_sd_get_cid(struct mmc_host *host, u32 ocr, u32 *cid)
 	 */
 	err = mmc_send_if_cond(host, ocr);
 	if (!err)
-		ocr |= 1 << 30;
+		ocr |= SD_OCR_CCS;
 
-	err = mmc_send_app_op_cond(host, ocr, NULL);
+	/*
+	 * If the host supports one of UHS-I modes, request the card
+	 * to switch to 1.8V signaling level.
+	 */
+	if (host->caps & (MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25 |
+	    MMC_CAP_UHS_SDR50 | MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_DDR50))
+		ocr |= SD_OCR_S18R;
+
+	/* If the host can supply more than 150mA, XPC should be set to 1. */
+	if (host->caps & (MMC_CAP_SET_XPC_330 | MMC_CAP_SET_XPC_300 |
+	    MMC_CAP_SET_XPC_180))
+		ocr |= SD_OCR_XPC;
+
+try_again:
+	err = mmc_send_app_op_cond(host, ocr, &rocr);
 	if (err)
 		return err;
 
+	/*
+	 * In case CCS and S18A in the response is set, start Signal Voltage
+	 * Switch procedure. SPI mode doesn't support CMD11.
+	 */
+	if (!mmc_host_is_spi(host) && ((rocr & 0x41000000) == 0x41000000)) {
+		err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_180);
+		if (err) {
+			ocr &= ~SD_OCR_S18R;
+			goto try_again;
+		}
+	}
+
 	if (mmc_host_is_spi(host))
 		err = mmc_send_cid(host, cid);
 	else
@@ -773,6 +800,11 @@ int mmc_attach_sd(struct mmc_host *host)
 	BUG_ON(!host);
 	WARN_ON(!host->claimed);
 
+	/* Make sure we are at 3.3V signalling voltage */
+	err = mmc_set_signal_voltage(host, MMC_SIGNAL_VOLTAGE_330);
+	if (err)
+		return err;
+
 	err = mmc_send_app_op_cond(host, 0, &ocr);
 	if (err)
 		return err;

drivers/mmc/host/sdhci.c

@@ -83,6 +83,8 @@ static void sdhci_dumpregs(struct sdhci_host *host)
 	printk(KERN_DEBUG DRIVER_NAME ": Cmd:      0x%08x | Max curr: 0x%08x\n",
 		sdhci_readw(host, SDHCI_COMMAND),
 		sdhci_readl(host, SDHCI_MAX_CURRENT));
+	printk(KERN_DEBUG DRIVER_NAME ": Host ctl2: 0x%08x\n",
+		sdhci_readw(host, SDHCI_HOST_CONTROL2));
 
 	if (host->flags & SDHCI_USE_ADMA)
 		printk(KERN_DEBUG DRIVER_NAME ": ADMA Err: 0x%08x | ADMA Ptr: 0x%08x\n",
@@ -1323,11 +1325,114 @@ static void sdhci_enable_sdio_irq(struct mmc_host *mmc, int enable)
 	spin_unlock_irqrestore(&host->lock, flags);
 }
 
+static int sdhci_start_signal_voltage_switch(struct mmc_host *mmc,
+	struct mmc_ios *ios)
+{
+	struct sdhci_host *host;
+	u8 pwr;
+	u16 clk, ctrl;
+	u32 present_state;
+
+	host = mmc_priv(mmc);
+
+	/*
+	 * Signal Voltage Switching is only applicable for Host Controllers
+	 * v3.00 and above.
+	 */
+	if (host->version < SDHCI_SPEC_300)
+		return 0;
+
+	/*
+	 * We first check whether the request is to set signalling voltage
+	 * to 3.3V. If so, we change the voltage to 3.3V and return quickly.
+	 */
+	ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+	if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330) {
+		/* Set 1.8V Signal Enable in the Host Control2 register to 0 */
+		ctrl &= ~SDHCI_CTRL_VDD_180;
+		sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+
+		/* Wait for 5ms */
+		usleep_range(5000, 5500);
+
+		/* 3.3V regulator output should be stable within 5 ms */
+		ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+		if (!(ctrl & SDHCI_CTRL_VDD_180))
+			return 0;
+		else {
+			printk(KERN_INFO DRIVER_NAME ": Switching to 3.3V "
+				"signalling voltage failed\n");
+			return -EIO;
+		}
+	} else if (!(ctrl & SDHCI_CTRL_VDD_180) &&
+		  (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_180)) {
+		/* Stop SDCLK */
+		clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+		clk &= ~SDHCI_CLOCK_CARD_EN;
+		sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+
+		/* Check whether DAT[3:0] is 0000 */
+		present_state = sdhci_readl(host, SDHCI_PRESENT_STATE);
+		if (!((present_state & SDHCI_DATA_LVL_MASK) >>
+		       SDHCI_DATA_LVL_SHIFT)) {
+			/*
+			 * Enable 1.8V Signal Enable in the Host Control2
+			 * register
+			 */
+			ctrl |= SDHCI_CTRL_VDD_180;
+			sdhci_writew(host, ctrl, SDHCI_HOST_CONTROL2);
+
+			/* Wait for 5ms */
+			usleep_range(5000, 5500);
+
+			ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
+			if (ctrl & SDHCI_CTRL_VDD_180) {
+				/* Provide SDCLK again and wait for 1ms*/
+				clk = sdhci_readw(host, SDHCI_CLOCK_CONTROL);
+				clk |= SDHCI_CLOCK_CARD_EN;
+				sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
+				usleep_range(1000, 1500);
+
+				/*
+				 * If DAT[3:0] level is 1111b, then the card
+				 * was successfully switched to 1.8V signaling.
+				 */
+				present_state = sdhci_readl(host,
+							SDHCI_PRESENT_STATE);
+				if ((present_state & SDHCI_DATA_LVL_MASK) ==
+				     SDHCI_DATA_LVL_MASK)
+					return 0;
+			}
+		}
+
+		/*
+		 * If we are here, that means the switch to 1.8V signaling
+		 * failed. We power cycle the card, and retry initialization
+		 * sequence by setting S18R to 0.
+		 */
+		pwr = sdhci_readb(host, SDHCI_POWER_CONTROL);
+		pwr &= ~SDHCI_POWER_ON;
+		sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
+
+		/* Wait for 1ms as per the spec */
+		usleep_range(1000, 1500);
+		pwr |= SDHCI_POWER_ON;
+		sdhci_writeb(host, pwr, SDHCI_POWER_CONTROL);
+
+		printk(KERN_INFO DRIVER_NAME ": Switching to 1.8V signalling "
+			"voltage failed, retrying with S18R set to 0\n");
+		return -EAGAIN;
+	} else
+		/* No signal voltage switch required */
+		return 0;
+}
+
 static const struct mmc_host_ops sdhci_ops = {
 	.request	= sdhci_request,
 	.set_ios	= sdhci_set_ios,
 	.get_ro		= sdhci_get_ro,
 	.enable_sdio_irq = sdhci_enable_sdio_irq,
+	.start_signal_voltage_switch	= sdhci_start_signal_voltage_switch,
 };
 
 /*****************************************************************************\
@@ -1808,7 +1913,9 @@ EXPORT_SYMBOL_GPL(sdhci_alloc_host);
 int sdhci_add_host(struct sdhci_host *host)
 {
 	struct mmc_host *mmc;
-	unsigned int caps, ocr_avail;
+	u32 caps[2];
+	u32 max_current_caps;
+	unsigned int ocr_avail;
 	int ret;
 
 	WARN_ON(host == NULL);
@@ -1831,12 +1938,15 @@ int sdhci_add_host(struct sdhci_host *host)
 			host->version);
 	}
 
-	caps = (host->quirks & SDHCI_QUIRK_MISSING_CAPS) ? host->caps :
+	caps[0] = (host->quirks & SDHCI_QUIRK_MISSING_CAPS) ? host->caps :
 		sdhci_readl(host, SDHCI_CAPABILITIES);
 
+	caps[1] = (host->version >= SDHCI_SPEC_300) ?
+		sdhci_readl(host, SDHCI_CAPABILITIES_1) : 0;
+
 	if (host->quirks & SDHCI_QUIRK_FORCE_DMA)
 		host->flags |= SDHCI_USE_SDMA;
-	else if (!(caps & SDHCI_CAN_DO_SDMA))
+	else if (!(caps[0] & SDHCI_CAN_DO_SDMA))
 		DBG("Controller doesn't have SDMA capability\n");
 	else
 		host->flags |= SDHCI_USE_SDMA;
@@ -1847,7 +1957,8 @@ int sdhci_add_host(struct sdhci_host *host)
 		host->flags &= ~SDHCI_USE_SDMA;
 	}
 
-	if ((host->version >= SDHCI_SPEC_200) && (caps & SDHCI_CAN_DO_ADMA2))
+	if ((host->version >= SDHCI_SPEC_200) &&
+		(caps[0] & SDHCI_CAN_DO_ADMA2))
 		host->flags |= SDHCI_USE_ADMA;
 
 	if ((host->quirks & SDHCI_QUIRK_BROKEN_ADMA) &&
@@ -1897,10 +2008,10 @@ int sdhci_add_host(struct sdhci_host *host)
 	}
 
 	if (host->version >= SDHCI_SPEC_300)
-		host->max_clk = (caps & SDHCI_CLOCK_V3_BASE_MASK)
+		host->max_clk = (caps[0] & SDHCI_CLOCK_V3_BASE_MASK)
 			>> SDHCI_CLOCK_BASE_SHIFT;
 	else
-		host->max_clk = (caps & SDHCI_CLOCK_BASE_MASK)
+		host->max_clk = (caps[0] & SDHCI_CLOCK_BASE_MASK)
 			>> SDHCI_CLOCK_BASE_SHIFT;
 
 	host->max_clk *= 1000000;
@@ -1916,7 +2027,7 @@ int sdhci_add_host(struct sdhci_host *host)
 	}
 
 	host->timeout_clk =
-		(caps & SDHCI_TIMEOUT_CLK_MASK) >> SDHCI_TIMEOUT_CLK_SHIFT;
+		(caps[0] & SDHCI_TIMEOUT_CLK_MASK) >> SDHCI_TIMEOUT_CLK_SHIFT;
 	if (host->timeout_clk == 0) {
 		if (host->ops->get_timeout_clock) {
 			host->timeout_clk = host->ops->get_timeout_clock(host);
@@ -1928,7 +2039,7 @@ int sdhci_add_host(struct sdhci_host *host)
 			return -ENODEV;
 		}
 	}
-	if (caps & SDHCI_TIMEOUT_CLK_UNIT)
+	if (caps[0] & SDHCI_TIMEOUT_CLK_UNIT)
 		host->timeout_clk *= 1000;
 
 	/*
@@ -1955,21 +2066,76 @@ int sdhci_add_host(struct sdhci_host *host)
 	if (!(host->quirks & SDHCI_QUIRK_FORCE_1_BIT_DATA))
 		mmc->caps |= MMC_CAP_4_BIT_DATA;
 
-	if (caps & SDHCI_CAN_DO_HISPD)
+	if (caps[0] & SDHCI_CAN_DO_HISPD)
 		mmc->caps |= MMC_CAP_SD_HIGHSPEED | MMC_CAP_MMC_HIGHSPEED;
 
 	if ((host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION) &&
 	    mmc_card_is_removable(mmc))
 		mmc->caps |= MMC_CAP_NEEDS_POLL;
 
+	/* UHS-I mode(s) supported by the host controller. */
+	if (host->version >= SDHCI_SPEC_300)
+		mmc->caps |= MMC_CAP_UHS_SDR12 | MMC_CAP_UHS_SDR25;
+
+	/* SDR104 supports also implies SDR50 support */
+	if (caps[1] & SDHCI_SUPPORT_SDR104)
+		mmc->caps |= MMC_CAP_UHS_SDR104 | MMC_CAP_UHS_SDR50;
+	else if (caps[1] & SDHCI_SUPPORT_SDR50)
+		mmc->caps |= MMC_CAP_UHS_SDR50;
+
+	if (caps[1] & SDHCI_SUPPORT_DDR50)
+		mmc->caps |= MMC_CAP_UHS_DDR50;
+
 	ocr_avail = 0;
-	if (caps & SDHCI_CAN_VDD_330)
+	/*
+	 * According to SD Host Controller spec v3.00, if the Host System
+	 * can afford more than 150mA, Host Driver should set XPC to 1. Also
+	 * the value is meaningful only if Voltage Support in the Capabilities
+	 * register is set. The actual current value is 4 times the register
+	 * value.
+	 */
+	max_current_caps = sdhci_readl(host, SDHCI_MAX_CURRENT);
+
+	if (caps[0] & SDHCI_CAN_VDD_330) {
+		int max_current_330;
+
 		ocr_avail |= MMC_VDD_32_33 | MMC_VDD_33_34;
-	if (caps & SDHCI_CAN_VDD_300)
+
+		max_current_330 = ((max_current_caps &
+				   SDHCI_MAX_CURRENT_330_MASK) >>
+				   SDHCI_MAX_CURRENT_330_SHIFT) *
+				   SDHCI_MAX_CURRENT_MULTIPLIER;
+
+		if (max_current_330 > 150)
+			mmc->caps |= MMC_CAP_SET_XPC_330;
+	}
+	if (caps[0] & SDHCI_CAN_VDD_300) {
+		int max_current_300;
+
 		ocr_avail |= MMC_VDD_29_30 | MMC_VDD_30_31;
-	if (caps & SDHCI_CAN_VDD_180)
+
+		max_current_300 = ((max_current_caps &
+				   SDHCI_MAX_CURRENT_300_MASK) >>
+				   SDHCI_MAX_CURRENT_300_SHIFT) *
+				   SDHCI_MAX_CURRENT_MULTIPLIER;
+
+		if (max_current_300 > 150)
+			mmc->caps |= MMC_CAP_SET_XPC_300;
+	}
+	if (caps[0] & SDHCI_CAN_VDD_180) {
+		int max_current_180;
+
 		ocr_avail |= MMC_VDD_165_195;
 
+		max_current_180 = ((max_current_caps &
+				   SDHCI_MAX_CURRENT_180_MASK) >>
+				   SDHCI_MAX_CURRENT_180_SHIFT) *
+				   SDHCI_MAX_CURRENT_MULTIPLIER;
+
+		if (max_current_180 > 150)
+			mmc->caps |= MMC_CAP_SET_XPC_180;
+	}
+
 	mmc->ocr_avail = ocr_avail;
 	mmc->ocr_avail_sdio = ocr_avail;
 	if (host->ocr_avail_sdio)
@@ -2029,7 +2195,7 @@ int sdhci_add_host(struct sdhci_host *host)
 	if (host->quirks & SDHCI_QUIRK_FORCE_BLK_SZ_2048) {
 		mmc->max_blk_size = 2;
 	} else {
-		mmc->max_blk_size = (caps & SDHCI_MAX_BLOCK_MASK) >>
+		mmc->max_blk_size = (caps[0] & SDHCI_MAX_BLOCK_MASK) >>
 				SDHCI_MAX_BLOCK_SHIFT;
 		if (mmc->max_blk_size >= 3) {
 			printk(KERN_WARNING "%s: Invalid maximum block size, "