mmc: rework selection of bus speed mode

Current implementation for bus speed mode selection is too
complicated. This patch is to simplify the codes and remove
some duplicate parts.

The following changes are including:
* Adds functions for each mode selection(HS, HS-DDR, HS200 and etc)
* Rearranged the mode selection sequence with supported device type
* Adds maximum speed for HS200 mode(hs200_max_dtr)
* Adds field definition for HS_TIMING of EXT_CSD
Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Tested-by: Jaehoon Chung <jh80.chung@samsung.com>
Acked-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <chris@printf.net>

drivers/mmc/core/debugfs.c

@@ -139,7 +139,7 @@ static int mmc_ios_show(struct seq_file *s, void *data)
 		str = "mmc DDR52";
 		break;
 	case MMC_TIMING_MMC_HS200:
-		str = "mmc high-speed SDR200";
+		str = "mmc HS200";
 		break;
 	default:
 		str = "invalid";

include/linux/mmc/card.h

@@ -63,6 +63,7 @@ struct mmc_ext_csd {
 	unsigned int            power_off_longtime;     /* Units: ms */
 	u8			power_off_notification;	/* state */
 	unsigned int		hs_max_dtr;
+	unsigned int		hs200_max_dtr;
 #define MMC_HIGH_26_MAX_DTR	26000000
 #define MMC_HIGH_52_MAX_DTR	52000000
 #define MMC_HIGH_DDR_MAX_DTR	52000000

include/linux/mmc/mmc.h

@@ -377,6 +377,10 @@ struct _mmc_csd {
 #define EXT_CSD_DDR_BUS_WIDTH_4	5	/* Card is in 4 bit DDR mode */
 #define EXT_CSD_DDR_BUS_WIDTH_8	6	/* Card is in 8 bit DDR mode */
 
+#define EXT_CSD_TIMING_BC	0	/* Backwards compatility */
+#define EXT_CSD_TIMING_HS	1	/* High speed */
+#define EXT_CSD_TIMING_HS200	2	/* HS200 */
+
 #define EXT_CSD_SEC_ER_EN	BIT(0)
 #define EXT_CSD_SEC_BD_BLK_EN	BIT(2)
 #define EXT_CSD_SEC_GB_CL_EN	BIT(4)