[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>

1 files changed, 119 insertions, 2 deletions

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 766bc544..2d5b930 100644
--- a/drivers/mmc/mmc.c
+++ b/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);
 }