mmc: Support for high speed SD cards

Modern SD cards support a clock speed of 50 MHz. Make sure we test for
this capability and do the song and dance required to activate it.

Activating high speed support actually modifies the TRAN_SPEED field
of the CSD. But as the spec says that the cards must report 50 MHz,
we might as well skip re-reading the CSD.

Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

1 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/mmc/protocol.h b/include/linux/mmc/protocol.h
index 45c51fd8..2dce60c 100644
--- a/include/linux/mmc/protocol.h
+++ b/include/linux/mmc/protocol.h
@@ -82,6 +82,7 @@
   /* class 8 */
 /* This is basically the same command as for MMC with some quirks. */
 #define SD_SEND_RELATIVE_ADDR     3   /* bcr                     R6  */
+#define SD_SWITCH                 6   /* adtc [31:0] See below   R1  */
 
   /* Application commands */
 #define SD_APP_SET_BUS_WIDTH      6   /* ac   [1:0] bus width    R1  */
@@ -101,6 +102,19 @@
  */
 
 /*
+ * SD_SWITCH argument format:
+ *
+ *      [31] Check (0) or switch (1)
+ *      [30:24] Reserved (0)
+ *      [23:20] Function group 6
+ *      [19:16] Function group 5
+ *      [15:12] Function group 4
+ *      [11:8] Function group 3
+ *      [7:4] Function group 2
+ *      [3:0] Function group 1
+ */
+
+/*
   MMC status in R1
   Type
   	e : error bit
@@ -285,6 +299,14 @@ struct _mmc_csd {
 #define MMC_SWITCH_MODE_WRITE_BYTE	0x03	/* Set target to value */
 
 /*
+ * SCR field definitions
+ */
+
+#define SCR_SPEC_VER_0      0           /* Implements system specification 1.0 - 1.01 */
+#define SCR_SPEC_VER_1      1           /* Implements system specification 1.10 */
+#define SCR_SPEC_VER_2      2           /* Implements system specification 2.00 */
+
+/*
  * SD bus widths
  */
 #define SD_BUS_WIDTH_1      0