Proper MMC command classes support

PATCH New Pierre Ossman 1 participant 3 messages May 17, 2005 MMC, SD and SDIO

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Pierre Ossman

author

2005-05-17 22:35 UTC #0 lore raw

cover Proper MMC command classes support

The MMC block layer currently contains an if-clause which only seems to serve the purpose of killing forward compatibility:

	if (card->csd.cmdclass & ~0x1ff)
		return -ENODEV;

This checks for (what I presume) command classes that were undefined when this code was written. Since these are now starting to be used, this code is causing a lot of problems. The following two patches tries to make a more sane check of the command classes.

(Note. The new command class is for high speed cards to allow higher transfer rates than normal)

Rgds
Pierre

Pierre Ossman

author

2005-05-17 22:17 UTC #1 lore raw

PATCH 1/2 Proper MMC command classes support

Defines for the different command classes as defined in the MMC and SD specifications.

Signed-off-by Pierre Ossman <[email protected]>

include/linux/mmc/protocol.h +27 -0

Index: linux-wbsd/include/linux/mmc/protocol.h
===================================================================
@@ -209,6 +209,33 @@
 #define CSD_SPEC_VER_2      2           /* Implements system specification 2.0 - 2.2 */
 #define CSD_SPEC_VER_3      3           /* Implements system specification 3.1 */
 
+/*
+ * Card Command Classes (CCC)
+ */
+#define CCC_BASIC		(1<<0)	/* (0) Basic protocol functions */
+					/* (CMD0,1,2,3,4,7,9,10,12,13,15) */
+#define CCC_STREAM_READ		(1<<1)	/* (1) Stream read commands */
+					/* (CMD11) */
+#define CCC_BLOCK_READ		(1<<2)	/* (2) Block read commands */
+					/* (CMD16,17,18) */
+#define CCC_STREAM_WRITE	(1<<3)	/* (3) Stream write commands */
+					/* (CMD20) */
+#define CCC_BLOCK_WRITE		(1<<4)	/* (4) Block write commands */
+					/* (CMD16,24,25,26,27) */
+#define CCC_ERASE		(1<<5)	/* (5) Ability to erase blocks */
+					/* (CMD32,33,34,35,36,37,38,39) */
+#define CCC_WRITE_PROT		(1<<6)	/* (6) Able to write protect blocks */
+					/* (CMD28,29,30) */
+#define CCC_LOCK_CARD		(1<<7)	/* (7) Able to lock down card */
+					/* (CMD16,CMD42) */
+#define CCC_APP_SPEC		(1<<8)	/* (8) Application specific */
+					/* (CMD55,56,57,ACMD*) */
+#define CCC_IO_MODE		(1<<9)	/* (9) I/O mode */
+					/* (CMD5,39,40,52,53) */
+#define CCC_SWITCH		(1<<10)	/* (10) High speed switch */
+					/* (CMD6,34,35,36,37,50) */
+					/* (11) Reserved */
+					/* (CMD?) */
 
 /*
  * SD bus widths

Pierre Ossman

author

2005-05-17 22:26 UTC #2 lore raw

PATCH 2/2 Proper MMC command classes support

In reply to Pierre Ossman

Removes the check for high command classes and instead checks that the command classes needed are present.
Previous solution killed forward compatibility at no apparent gain.

Signed-of-by Pierre Ossman <[email protected]>

This patch only checks for CCC_BLOCK_READ even though CCC_BLOCK_WRITE is also needed. My intention is to make the card read-only if the write command class is unavailable. But such a patch will conflict with the SD patches previously submitted. So I need to know which version should be used as a base.

drivers/mmc/mmc_block.c +4 -1

Index: linux-wbsd/drivers/mmc/mmc_block.c
===================================================================
@@ -443,7 +443,10 @@
 	struct mmc_blk_data *md;
 	int err;
 
-	if (card->csd.cmdclass & ~0x1ff)
+	/*
+	 * Check that the card supports the command class(es) we need.
+	 */
+	if (!(card->csd.cmdclass & CCC_BLOCK_READ))
 		return -ENODEV;
 
 	if (card->csd.read_blkbits < 9) {