[PATCH V5 1/3] mmc: sdhci: Add support for O2 eMMC HS200 mode

["ernest.zhang" <ernest.zhang@bayhubtech.com>]

When use eMMC as boot device, the eMMC signaling voltage is tied to 1.8v
fixed output voltage, bios can set o2 sd host controller PCI configuration
register 0x308 bit4 to 1 to let driver skip 3.3v signaling voltage and
direct use 1.8v singling voltage in eMMC initialize process.

Changes in V5:
	Modify code format to pass checkpatch.pl check and add a summary
	of what has changed in each version.

Changes in V4:
	Skip SDIO and SD initalization when register 0x308 bit 4 is set,
	and modify some typo.

Changes in V3:
	Rebase the patch on the mmc tree 'next' branch.

Changes in V2:
	Modify code format, and delete unused code path.

Changes in V1:
	Check PCIe register 0x308 bit 4 and skip eMMC 3.3v initialization
	process if it is set to 1.

Signed-off-by: ernest.zhang <ernest.zhang@bayhubtech.com>
---
 drivers/mmc/host/sdhci-pci-o2micro.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/mmc/host/sdhci-pci-o2micro.c b/drivers/mmc/host/sdhci-pci-o2micro.c
index 555970a..ba59db6a 100644
--- a/drivers/mmc/host/sdhci-pci-o2micro.c
+++ b/drivers/mmc/host/sdhci-pci-o2micro.c
@@ -3,6 +3,7 @@
  *
  * Authors: Peter Guo <peter.guo@bayhubtech.com>
  *          Adam Lee <adam.lee@canonical.com>
+ *          Ernest Zhang <ernest.zhang@bayhubtech.com>
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
@@ -39,6 +40,7 @@
 #define O2_SD_MISC_CTRL4	0xFC
 #define O2_SD_TUNING_CTRL	0x300
 #define O2_SD_PLL_SETTING	0x304
+#define O2_SD_MISC_SETTING	0x308
 #define O2_SD_CLK_SETTING	0x328
 #define O2_SD_CAP_REG2		0x330
 #define O2_SD_CAP_REG0		0x334
@@ -184,6 +186,7 @@ int sdhci_pci_o2_probe_slot(struct sdhci_pci_slot *slot)
 	struct sdhci_pci_chip *chip;
 	struct sdhci_host *host;
 	u32 reg;
+	int ret;
 
 	chip = slot->chip;
 	host = slot->host;
@@ -197,6 +200,21 @@ int sdhci_pci_o2_probe_slot(struct sdhci_pci_slot *slot)
 		if (reg & 0x1)
 			host->quirks |= SDHCI_QUIRK_MULTIBLOCK_READ_ACMD12;
 
+		if (chip->pdev->device == PCI_DEVICE_ID_O2_SEABIRD0) {
+			ret = pci_read_config_dword(chip->pdev,
+						    O2_SD_MISC_SETTING, &reg);
+			if (ret)
+				return -EIO;
+			if (reg & (1 << 4)) {
+				pr_info("%s: emmc 1.8v flag is set, force 1.8v signaling voltage\n",
+					mmc_hostname(host->mmc));
+				host->flags &= ~SDHCI_SIGNALING_330;
+				host->flags |= SDHCI_SIGNALING_180;
+				host->mmc->caps2 |= MMC_CAP2_NO_SD;
+				host->mmc->caps2 |= MMC_CAP2_NO_SDIO;
+			}
+		}
+
 		if (chip->pdev->device != PCI_DEVICE_ID_O2_FUJIN2)
 			break;
 		/* set dll watch dog timer */
-- 
2.7.4