[PATCH] mmc: Add support for mmc v4 high speed mode

This adds support for the high-speed modes defined by mmc v4
(assuming the host controller is up to it). On a TI sdhci controller,
it improves read speed from 1.3MBps to 2.3MBps. The TI controller can
only go up to 24MHz, but everything helps. Another person has taken
this basic patch and used it on a Nokia 770 to get a bigger boost
because that controller can run at 48MHZ.

Signed-off-by: Philip Langdale <philipl@overt.org>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

drivers/mmc/mmc.c

@@ -4,6 +4,7 @@
  *  Copyright (C) 2003-2004 Russell King, All Rights Reserved.
  *  SD support Copyright (C) 2004 Ian Molton, All Rights Reserved.
  *  SD support Copyright (C) 2005 Pierre Ossman, All Rights Reserved.
+ *  MMCv4 support Copyright (C) 2006 Philip Langdale, All Rights Reserved.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 2 as
@@ -953,6 +954,114 @@ static void mmc_read_csds(struct mmc_host *host)
 	}
 }
 
+static void mmc_process_ext_csds(struct mmc_host *host)
+{
+	int err;
+	struct mmc_card *card;
+
+	struct mmc_request mrq;
+	struct mmc_command cmd;
+	struct mmc_data data;
+
+	struct scatterlist sg;
+
+	/*
+	 * As the ext_csd is so large and mostly unused, we don't store the
+	 * raw block in mmc_card.
+	 */
+	u8 *ext_csd;
+	ext_csd = kmalloc(512, GFP_KERNEL);
+	if (!ext_csd) {
+		printk("%s: could not allocate a buffer to receive the ext_csd."
+		       "mmc v4 cards will be treated as v3.\n",
+			mmc_hostname(host));
+		return;
+	}
+
+	list_for_each_entry(card, &host->cards, node) {
+		if (card->state & (MMC_STATE_DEAD|MMC_STATE_PRESENT))
+			continue;
+		if (mmc_card_sd(card))
+			continue;
+		if (card->csd.mmca_vsn < CSD_SPEC_VER_4)
+			continue;
+
+		err = mmc_select_card(host, card);
+		if (err != MMC_ERR_NONE) {
+			mmc_card_set_dead(card);
+			continue;
+		}
+
+		memset(&cmd, 0, sizeof(struct mmc_command));
+
+		cmd.opcode = MMC_SEND_EXT_CSD;
+		cmd.arg = 0;
+		cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
+
+		memset(&data, 0, sizeof(struct mmc_data));
+
+		mmc_set_data_timeout(&data, card, 0);
+
+		data.blksz = 512;
+		data.blocks = 1;
+		data.flags = MMC_DATA_READ;
+		data.sg = &sg;
+		data.sg_len = 1;
+
+		memset(&mrq, 0, sizeof(struct mmc_request));
+
+		mrq.cmd = &cmd;
+		mrq.data = &data;
+
+		sg_init_one(&sg, ext_csd, 512);
+
+		mmc_wait_for_req(host, &mrq);
+
+		if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
+			mmc_card_set_dead(card);
+			continue;
+		}
+
+		switch (ext_csd[EXT_CSD_CARD_TYPE]) {
+		case EXT_CSD_CARD_TYPE_52 | EXT_CSD_CARD_TYPE_26:
+			card->ext_csd.hs_max_dtr = 52000000;
+			break;
+		case EXT_CSD_CARD_TYPE_26:
+			card->ext_csd.hs_max_dtr = 26000000;
+			break;
+		default:
+			/* MMC v4 spec says this cannot happen */
+			printk("%s: card is mmc v4 but doesn't support "
+			       "any high-speed modes.\n",
+				mmc_hostname(card->host));
+			mmc_card_set_bad(card);
+			continue;
+		}
+
+		/* Activate highspeed support. */
+		cmd.opcode = MMC_SWITCH;
+		cmd.arg = (MMC_SWITCH_MODE_WRITE_BYTE << 24) |
+			  (EXT_CSD_HS_TIMING << 16) |
+			  (1 << 8) |
+			  EXT_CSD_CMD_SET_NORMAL;
+		cmd.flags = MMC_RSP_R1B | MMC_CMD_AC;
+
+		err = mmc_wait_for_cmd(host, &cmd, CMD_RETRIES);
+		if (err != MMC_ERR_NONE) {
+			printk("%s: failed to switch card to mmc v4 "
+			       "high-speed mode.\n",
+			       mmc_hostname(card->host));
+			continue;
+		}
+
+		mmc_card_set_highspeed(card);
+	}
+
+	kfree(ext_csd);
+
+	mmc_deselect_cards(host);
+}
+
 static void mmc_read_scrs(struct mmc_host *host)
 {
 	int err;
@@ -1031,8 +1140,14 @@ static unsigned int mmc_calculate_clock(struct mmc_host *host)
 	unsigned int max_dtr = host->f_max;
 
 	list_for_each_entry(card, &host->cards, node)
-		if (!mmc_card_dead(card) && max_dtr > card->csd.max_dtr)
-			max_dtr = card->csd.max_dtr;
+		if (!mmc_card_dead(card)) {
+			if (mmc_card_highspeed(card)) {
+				if (max_dtr > card->ext_csd.hs_max_dtr)
+			    		max_dtr = card->ext_csd.hs_max_dtr;
+			} else if (max_dtr > card->csd.max_dtr) {
+				max_dtr = card->csd.max_dtr;
+			}
+		}
 
 	pr_debug("%s: selected %d.%03dMHz transfer rate\n",
 		 mmc_hostname(host),
@@ -1152,6 +1267,8 @@ static void mmc_setup(struct mmc_host *host)
 
 	if (host->mode == MMC_MODE_SD)
 		mmc_read_scrs(host);
+	else
+		mmc_process_ext_csds(host);
 }
 
 

include/linux/mmc/card.h

@@ -39,6 +39,10 @@ struct mmc_csd {
 				write_misalign:1;
 };
 
+struct mmc_ext_csd {
+	unsigned int		hs_max_dtr;
+};
+
 struct sd_scr {
 	unsigned char		sda_vsn;
 	unsigned char		bus_widths;
@@ -62,11 +66,13 @@ struct mmc_card {
 #define MMC_STATE_BAD		(1<<2)		/* unrecognised device */
 #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 mmc4 highspeed mode */
 	u32			raw_cid[4];	/* raw card CID */
 	u32			raw_csd[4];	/* raw card CSD */
 	u32			raw_scr[2];	/* raw card SCR */
 	struct mmc_cid		cid;		/* card identification */
 	struct mmc_csd		csd;		/* card specific */
+	struct mmc_ext_csd	ext_csd;	/* mmc v4 extended card specific */
 	struct sd_scr		scr;		/* extra SD information */
 };
 
@@ -75,12 +81,14 @@ struct mmc_card {
 #define mmc_card_bad(c)		((c)->state & MMC_STATE_BAD)
 #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_set_present(c)	((c)->state |= MMC_STATE_PRESENT)
 #define mmc_card_set_dead(c)	((c)->state |= MMC_STATE_DEAD)
 #define mmc_card_set_bad(c)	((c)->state |= MMC_STATE_BAD)
 #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_name(c)	((c)->cid.prod_name)
 #define mmc_card_id(c)		((c)->dev.bus_id)

include/linux/mmc/protocol.h

@@ -25,14 +25,16 @@
 #ifndef MMC_MMC_PROTOCOL_H
 #define MMC_MMC_PROTOCOL_H
 
-/* Standard MMC commands (3.1)           type  argument     response */
+/* Standard MMC commands (4.1)           type  argument     response */
    /* class 1 */
 #define	MMC_GO_IDLE_STATE         0   /* bc                          */
 #define MMC_SEND_OP_COND          1   /* bcr  [31:0] OCR         R3  */
 #define MMC_ALL_SEND_CID          2   /* bcr                     R2  */
 #define MMC_SET_RELATIVE_ADDR     3   /* ac   [31:16] RCA        R1  */
 #define MMC_SET_DSR               4   /* bc   [31:16] RCA            */
+#define MMC_SWITCH                6   /* ac   [31:0] See below   R1b */
 #define MMC_SELECT_CARD           7   /* ac   [31:16] RCA        R1  */
+#define MMC_SEND_EXT_CSD          8   /* adtc                    R1  */
 #define MMC_SEND_CSD              9   /* ac   [31:16] RCA        R2  */
 #define MMC_SEND_CID             10   /* ac   [31:16] RCA        R2  */
 #define MMC_READ_DAT_UNTIL_STOP  11   /* adtc [31:0] dadr        R1  */
@@ -87,6 +89,17 @@
 #define SD_APP_OP_COND           41   /* bcr  [31:0] OCR         R3  */
 #define SD_APP_SEND_SCR          51   /* adtc                    R1  */
 
+/*
+ * MMC_SWITCH argument format:
+ *
+ *	[31:26] Always 0
+ *	[25:24] Access Mode
+ *	[23:16] Location of target Byte in EXT_CSD
+ *	[15:08] Value Byte
+ *	[07:03] Always 0
+ *	[02:00] Command Set
+ */
+
 /*
   MMC status in R1
   Type
@@ -230,13 +243,41 @@ struct _mmc_csd {
 
 #define CSD_STRUCT_VER_1_0  0           /* Valid for system specification 1.0 - 1.2 */
 #define CSD_STRUCT_VER_1_1  1           /* Valid for system specification 1.4 - 2.2 */
-#define CSD_STRUCT_VER_1_2  2           /* Valid for system specification 3.1       */
+#define CSD_STRUCT_VER_1_2  2           /* Valid for system specification 3.1 - 3.2 - 3.31 - 4.0 - 4.1 */
+#define CSD_STRUCT_EXT_CSD  3           /* Version is coded in CSD_STRUCTURE in EXT_CSD */
 
 #define CSD_SPEC_VER_0      0           /* Implements system specification 1.0 - 1.2 */
 #define CSD_SPEC_VER_1      1           /* Implements system specification 1.4 */
 #define CSD_SPEC_VER_2      2           /* Implements system specification 2.0 - 2.2 */
-#define CSD_SPEC_VER_3      3           /* Implements system specification 3.1 */
+#define CSD_SPEC_VER_3      3           /* Implements system specification 3.1 - 3.2 - 3.31 */
+#define CSD_SPEC_VER_4      4           /* Implements system specification 4.0 - 4.1 */
+
+/*
+ * EXT_CSD fields
+ */
+
+#define EXT_CSD_HS_TIMING	185	/* R/W */
+#define EXT_CSD_CARD_TYPE	196	/* RO */
+
+/*
+ * EXT_CSD field definitions
+ */
+
+#define EXT_CSD_CMD_SET_NORMAL		(1<<0)
+#define EXT_CSD_CMD_SET_SECURE		(1<<1)
+#define EXT_CSD_CMD_SET_CPSECURE	(1<<2)
+
+#define EXT_CSD_CARD_TYPE_26	(1<<0)	/* Card can run at 26MHz */
+#define EXT_CSD_CARD_TYPE_52	(1<<1)	/* Card can run at 52MHz */
+
+/*
+ * MMC_SWITCH access modes
+ */
 
+#define MMC_SWITCH_MODE_CMD_SET		0x00	/* Change the command set */
+#define MMC_SWITCH_MODE_SET_BITS	0x01	/* Set bits which are 1 in value */
+#define MMC_SWITCH_MODE_CLEAR_BITS	0x02	/* Clear bits which are 1 in value */
+#define MMC_SWITCH_MODE_WRITE_BYTE	0x03	/* Set target to value */
 
 /*
  * SD bus widths