[PATCH 2.6.19] mmc: Add support for SDHC cards

[Philip Langdale <plangdale@vmware.com>]

Hi all,

Thanks to the generous donation of an SDHC card by John Gilmore, and the
surprisingly enlightened decision by the SD Card Association to publish
useful specs, I've been able to bash out support for SDHC. The changes
are not too profound:

i) Add a card flag indicating the card uses block level addressing and check
it in the block driver. As we never took advantage of byte-level addressing,
this simply involves skipping the block -> byte translation when sending commands.

ii) The layout of the CSD is changed - a set of fields are discarded to make space
for a larger C_SIZE. We did not reference any of the discarded fields except those
related to the C_SIZE.

iii) Read and write timeouts are fixed values and not calculated from CSD values.

iv) Before invoking SEND_APP_OP_COND, we must invoke the new SEND_IF_COND to inform
the card we support SDHC.

I've done some basic read and write tests and everything seems to work fine but one
should obviously use caution in case it eats your data.

Addendum: Similar spec changes were introduced by the MMC Association in version 4.2
to switch to block addressing. We do not have access to the 4.2 spec or even a change
summary as we did for 3 -> 4. My guess as to what's changed looks something like the
following:

i) A new field is added to the ext_csd to store the capacity that cannot be described
using existing csd fields.

ii) A new field is added to the ext_csd to indicate the need for block addressing.

iii) A new write-only field is added to the ext_csd which has to be toggled to tell the
card that the host supports block-addressing. But perhaps compatibility requires that
a new command be used like for SDHC...

If someone has access to the spec and can shed some light on the subject in a legal way,
please let us know. Of course, I don't think there are any MMC HC cards on the market
yet, but one was announced last month.

--phil

Signed-off-by: Philipl Langdale <philipl@overt.org>
---

 drivers/mmc/mmc.c            |   40 +++++++++++++++++++++++++++++++++++-----
 drivers/mmc/mmc_block.c      |    4 +++-
 include/linux/mmc/card.h     |    3 +++
 include/linux/mmc/mmc.h      |    1 +
 include/linux/mmc/protocol.h |   13 ++++++++++++-
 5 files changed, 54 insertions(+), 7 deletions(-)

diff -urN linux-2.6.19/drivers/mmc/mmc_block.c linux-2.6.19-sdhc/drivers/mmc/mmc_block.c
--- linux-2.6.19/drivers/mmc/mmc_block.c	2006-12-21 20:29:49.000000000 -0800
+++ linux-2.6.19-sdhc/drivers/mmc/mmc_block.c	2006-12-22 08:42:56.000000000 -0800
@@ -237,7 +237,9 @@
 		brq.mrq.cmd = &brq.cmd;
 		brq.mrq.data = &brq.data;

-		brq.cmd.arg = req->sector << 9;
+		brq.cmd.arg = req->sector;
+		if (!mmc_card_blockaddr(card))
+			brq.cmd.arg <<= 9;
 		brq.cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
 		brq.data.blksz = 1 << md->block_bits;
 		brq.data.blocks = req->nr_sectors >> (md->block_bits - 9);
diff -urN linux-2.6.19/drivers/mmc/mmc.c linux-2.6.19-sdhc/drivers/mmc/mmc.c
--- linux-2.6.19/drivers/mmc/mmc.c	2006-12-21 20:29:49.000000000 -0800
+++ linux-2.6.19-sdhc/drivers/mmc/mmc.c	2006-12-22 09:57:41.000000000 -0800
@@ -289,7 +289,10 @@
 		else
 			limit_us = 100000;

-		if (timeout_us > limit_us) {
+		/*
+		 * SDHC cards always use these fixed values.
+		 */
+		if (timeout_us > limit_us || mmc_card_blockaddr(card)) {
 			data->timeout_ns = limit_us * 1000;
 			data->timeout_clks = 0;
 		}
@@ -588,12 +591,15 @@

 	if (mmc_card_sd(card)) {
 		csd_struct = UNSTUFF_BITS(resp, 126, 2);
-		if (csd_struct != 0) {
+		if (csd_struct != 0 && csd_struct != 1) {
 			printk("%s: unrecognised CSD structure version %d\n",
 				mmc_hostname(card->host), csd_struct);
 			mmc_card_set_bad(card);
 			return;
 		}
+		if (csd_struct == 1) {
+			mmc_card_set_blockaddr(card);
+		}

 		m = UNSTUFF_BITS(resp, 115, 4);
 		e = UNSTUFF_BITS(resp, 112, 3);
@@ -605,9 +611,14 @@
 		csd->max_dtr	  = tran_exp[e] * tran_mant[m];
 		csd->cmdclass	  = UNSTUFF_BITS(resp, 84, 12);

-		e = UNSTUFF_BITS(resp, 47, 3);
-		m = UNSTUFF_BITS(resp, 62, 12);
-		csd->capacity	  = (1 + m) << (e + 2);
+		if (csd_struct == 0) {
+			e = UNSTUFF_BITS(resp, 47, 3);
+			m = UNSTUFF_BITS(resp, 62, 12);
+			csd->capacity	  = (1 + m) << (e + 2);
+		} else if (csd_struct == 1) {
+			m = UNSTUFF_BITS(resp, 48, 22);
+			csd->capacity     = (1 + m) << 10;
+		}

 		csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
 		csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
@@ -824,6 +835,25 @@
 {
 	struct mmc_command cmd;
 	int i, err = 0;
+	static const u8 test_pattern = 0xAA;
+
+	/*
+	 * To support SD 2.0 cards, we must always invoke SD_SEND_IF_COND
+	 * before SD_APP_OP_COND. This command will harmlessly fail for
+	 * SD 1.0 and MMC cards (fortunately including MMC 4 cards).
+	 */
+	cmd.opcode = SD_SEND_IF_COND;
+	cmd.arg = ((host->ocr_avail & 0xFF8000) != 0) << 8 | test_pattern;
+	cmd.flags = MMC_RSP_R7 | MMC_CMD_BCR;
+
+	err = mmc_wait_for_cmd(host, &cmd, 0);
+	if (err == MMC_ERR_NONE) {
+		if ((cmd.resp[0] & 0xFF) != test_pattern) {
+			return MMC_ERR_FAILED;
+		} else if (ocr != 0) {
+			ocr |= 1 << 30;
+		}
+	}

 	cmd.opcode = SD_APP_OP_COND;
 	cmd.arg = ocr;
diff -urN linux-2.6.19/include/linux/mmc/card.h linux-2.6.19-sdhc/include/linux/mmc/card.h
--- linux-2.6.19/include/linux/mmc/card.h	2006-12-21 20:29:49.000000000 -0800
+++ linux-2.6.19-sdhc/include/linux/mmc/card.h	2006-12-22 08:42:56.000000000 -0800
@@ -71,6 +71,7 @@
 #define MMC_STATE_SDCARD	(1<<3)		/* is an SD card */
 #define MMC_STATE_READONLY	(1<<4)		/* card is read-only */
 #define MMC_STATE_HIGHSPEED	(1<<5)		/* card is in high speed mode */
+#define MMC_STATE_BLOCKADDR	(1<<6)		/* card uses block-addressing */
 	u32			raw_cid[4];	/* raw card CID */
 	u32			raw_csd[4];	/* raw card CSD */
 	u32			raw_scr[2];	/* raw card SCR */
@@ -87,6 +88,7 @@
 #define mmc_card_sd(c)		((c)->state & MMC_STATE_SDCARD)
 #define mmc_card_readonly(c)	((c)->state & MMC_STATE_READONLY)
 #define mmc_card_highspeed(c)	((c)->state & MMC_STATE_HIGHSPEED)
+#define mmc_card_blockaddr(c)	((c)->state & MMC_STATE_BLOCKADDR)

 #define mmc_card_set_present(c)	((c)->state |= MMC_STATE_PRESENT)
 #define mmc_card_set_dead(c)	((c)->state |= MMC_STATE_DEAD)
@@ -94,6 +96,7 @@
 #define mmc_card_set_sd(c)	((c)->state |= MMC_STATE_SDCARD)
 #define mmc_card_set_readonly(c) ((c)->state |= MMC_STATE_READONLY)
 #define mmc_card_set_highspeed(c) ((c)->state |= MMC_STATE_HIGHSPEED)
+#define mmc_card_set_blockaddr(c) ((c)->state |= MMC_STATE_BLOCKADDR)

 #define mmc_card_name(c)	((c)->cid.prod_name)
 #define mmc_card_id(c)		((c)->dev.bus_id)
diff -urN linux-2.6.19/include/linux/mmc/mmc.h linux-2.6.19-sdhc/include/linux/mmc/mmc.h
--- linux-2.6.19/include/linux/mmc/mmc.h	2006-11-29 13:57:37.000000000 -0800
+++ linux-2.6.19-sdhc/include/linux/mmc/mmc.h	2006-12-22 08:42:56.000000000 -0800
@@ -43,6 +43,7 @@
 #define MMC_RSP_R2	(MMC_RSP_PRESENT|MMC_RSP_136|MMC_RSP_CRC)
 #define MMC_RSP_R3	(MMC_RSP_PRESENT)
 #define MMC_RSP_R6	(MMC_RSP_PRESENT|MMC_RSP_CRC)
+#define MMC_RSP_R7	(MMC_RSP_PRESENT|MMC_RSP_CRC)

 #define mmc_resp_type(cmd)	((cmd)->flags & (MMC_RSP_PRESENT|MMC_RSP_136|MMC_RSP_CRC|MMC_RSP_BUSY|MMC_RSP_OPCODE))

diff -urN linux-2.6.19/include/linux/mmc/protocol.h linux-2.6.19-sdhc/include/linux/mmc/protocol.h
--- linux-2.6.19/include/linux/mmc/protocol.h	2006-12-21 20:29:49.000000000 -0800
+++ linux-2.6.19-sdhc/include/linux/mmc/protocol.h	2006-12-22 08:42:56.000000000 -0800
@@ -79,9 +79,12 @@
 #define MMC_GEN_CMD              56   /* adtc [0] RD/WR          R1  */

 /* SD commands                           type  argument     response */
-  /* class 8 */
+  /* class 0 */
 /* This is basically the same command as for MMC with some quirks. */
 #define SD_SEND_RELATIVE_ADDR     3   /* bcr                     R6  */
+#define SD_SEND_IF_COND           8   /* bcr  [11:0] See below   R7  */
+
+  /* class 10 */
 #define SD_SWITCH                 6   /* adtc [31:0] See below   R1  */

   /* Application commands */
@@ -115,6 +118,14 @@
  */

 /*
+ * SD_SEND_IF_COND argument format:
+ *
+ *	[31:12] Reserved (0)
+ *	[11:8] Host Voltage Supply Flags
+ *	[7:0] Check Pattern (0xAA)
+ */
+
+/*
   MMC status in R1
   Type
   	e : error bit