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>

3 files changed, 146 insertions, 5 deletions

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 82b7643c165..9d190022a49 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -1157,6 +1157,116 @@ static void mmc_read_scrs(struct mmc_host *host)
         mmc_deselect_cards(host);
 }
 
+static void mmc_read_switch_caps(struct mmc_host *host)
+{
+        int err;
+        struct mmc_card *card;
+        struct mmc_request mrq;
+        struct mmc_command cmd;
+        struct mmc_data data;
+        unsigned char *status;
+        struct scatterlist sg;
+
+        status = kmalloc(64, GFP_KERNEL);
+        if (!status) {
+                printk(KERN_WARNING "%s: Unable to allocate buffer for "
+                        "reading switch capabilities.\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->scr.sda_vsn < SCR_SPEC_VER_1)
+                        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 = SD_SWITCH;
+                cmd.arg = 0x00FFFFF1;
+                cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
+
+                memset(&data, 0, sizeof(struct mmc_data));
+
+                mmc_set_data_timeout(&data, card, 0);
+
+                data.blksz = 64;
+                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, status, 64);
+
+                mmc_wait_for_req(host, &mrq);
+
+                if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
+                        mmc_card_set_dead(card);
+                        continue;
+                }
+
+                if (status[13] & 0x02)
+                        card->sw_caps.hs_max_dtr = 50000000;
+
+                memset(&cmd, 0, sizeof(struct mmc_command));
+
+                cmd.opcode = SD_SWITCH;
+                cmd.arg = 0x80FFFFF1;
+                cmd.flags = MMC_RSP_R1 | MMC_CMD_ADTC;
+
+                memset(&data, 0, sizeof(struct mmc_data));
+
+                mmc_set_data_timeout(&data, card, 0);
+
+                data.blksz = 64;
+                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, status, 64);
+
+                mmc_wait_for_req(host, &mrq);
+
+                if (cmd.error != MMC_ERR_NONE || data.error != MMC_ERR_NONE) {
+                        mmc_card_set_dead(card);
+                        continue;
+                }
+
+                if ((status[16] & 0xF) != 1) {
+                        printk(KERN_WARNING "%s: Problem switching card "
+                                "into high-speed mode!\n",
+                                mmc_hostname(host));
+                        continue;
+                }
+
+                mmc_card_set_highspeed(card);
+        }
+
+        kfree(status);
+
+        mmc_deselect_cards(host);
+}
+
 static unsigned int mmc_calculate_clock(struct mmc_host *host)
 {
         struct mmc_card *card;
@@ -1164,9 +1274,12 @@ static unsigned int mmc_calculate_clock(struct mmc_host *host)
 
         list_for_each_entry(card, &host->cards, node)
                 if (!mmc_card_dead(card)) {
-                        if (mmc_card_highspeed(card)) {
+                        if (mmc_card_highspeed(card) && mmc_card_sd(card)) {
+                                if (max_dtr > card->sw_caps.hs_max_dtr)
+                                        max_dtr = card->sw_caps.hs_max_dtr;
+                        } else if (mmc_card_highspeed(card) && !mmc_card_sd(card)) {
                                 if (max_dtr > card->ext_csd.hs_max_dtr)
-                                        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;
                         }
@@ -1288,9 +1401,10 @@ static void mmc_setup(struct mmc_host *host)
 
         mmc_read_csds(host);
 
-        if (host->mode == MMC_MODE_SD)
+        if (host->mode == MMC_MODE_SD) {
                 mmc_read_scrs(host);
-        else
+                mmc_read_switch_caps(host);
+        } else
                 mmc_process_ext_csds(host);
 }
 
diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index ce25256f80d..d0e6a549761 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -50,6 +50,10 @@ struct sd_scr {
 #define SD_SCR_BUS_WIDTH_4      (1<<2)
 };
 
+struct sd_switch_caps {
+        unsigned int            hs_max_dtr;
+};
+
 struct mmc_host;
 
 /*
@@ -66,7 +70,7 @@ 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 */
+#define MMC_STATE_HIGHSPEED     (1<<5)          /* card is in high speed mode */
         u32                     raw_cid[4];     /* raw card CID */
         u32                     raw_csd[4];     /* raw card CSD */
         u32                     raw_scr[2];     /* raw card SCR */
@@ -74,6 +78,7 @@ struct mmc_card {
         struct mmc_csd          csd;            /* card specific */
         struct mmc_ext_csd      ext_csd;        /* mmc v4 extended card specific */
         struct sd_scr           scr;            /* extra SD information */
+        struct sd_switch_caps   sw_caps;        /* switch (CMD6) caps */
 };
 
 #define mmc_card_present(c)     ((c)->state & MMC_STATE_PRESENT)
diff --git a/include/linux/mmc/protocol.h b/include/linux/mmc/protocol.h
index 45c51fd8578..2dce60c43f4 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