mmc: Add support for SDHC cards

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.

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

1 files changed, 112 insertions, 28 deletions

diff --git a/drivers/mmc/mmc.c b/drivers/mmc/mmc.c
index 105f419d08cb..b48c277312de 100644
--- a/drivers/mmc/mmc.c
+++ b/drivers/mmc/mmc.c
@@ -289,7 +289,10 @@ void mmc_set_data_timeout(struct mmc_data *data, const struct mmc_card *card,
                 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;
                 }
@@ -372,7 +375,7 @@ static inline void mmc_set_ios(struct mmc_host *host)
                  mmc_hostname(host), ios->clock, ios->bus_mode,
                  ios->power_mode, ios->chip_select, ios->vdd,
                  ios->bus_width);
-        
+
         host->ops->set_ios(host, ios);
 }
 
@@ -588,34 +591,65 @@ static void mmc_decode_csd(struct mmc_card *card)
 
         if (mmc_card_sd(card)) {
                 csd_struct = UNSTUFF_BITS(resp, 126, 2);
-                if (csd_struct != 0) {
+
+                switch (csd_struct) {
+                case 0:
+                        m = UNSTUFF_BITS(resp, 115, 4);
+                        e = UNSTUFF_BITS(resp, 112, 3);
+                        csd->tacc_ns     = (tacc_exp[e] * tacc_mant[m] + 9) / 10;
+                        csd->tacc_clks   = UNSTUFF_BITS(resp, 104, 8) * 100;
+
+                        m = UNSTUFF_BITS(resp, 99, 4);
+                        e = UNSTUFF_BITS(resp, 96, 3);
+                        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);
+
+                        csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
+                        csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
+                        csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
+                        csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
+                        csd->r2w_factor = UNSTUFF_BITS(resp, 26, 3);
+                        csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
+                        csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
+                        break;
+                case 1:
+                        /*
+                         * This is a block-addressed SDHC card. Most
+                         * interesting fields are unused and have fixed
+                         * values. To avoid getting tripped by buggy cards,
+                         * we assume those fixed values ourselves.
+                         */
+                        mmc_card_set_blockaddr(card);
+
+                        csd->tacc_ns     = 0; /* Unused */
+                        csd->tacc_clks   = 0; /* Unused */
+
+                        m = UNSTUFF_BITS(resp, 99, 4);
+                        e = UNSTUFF_BITS(resp, 96, 3);
+                        csd->max_dtr      = tran_exp[e] * tran_mant[m];
+                        csd->cmdclass     = UNSTUFF_BITS(resp, 84, 12);
+
+                        m = UNSTUFF_BITS(resp, 48, 22);
+                        csd->capacity     = (1 + m) << 10;
+
+                        csd->read_blkbits = 9;
+                        csd->read_partial = 0;
+                        csd->write_misalign = 0;
+                        csd->read_misalign = 0;
+                        csd->r2w_factor = 4; /* Unused */
+                        csd->write_blkbits = 9;
+                        csd->write_partial = 0;
+                        break;
+                default:
                         printk("%s: unrecognised CSD structure version %d\n",
                                 mmc_hostname(card->host), csd_struct);
                         mmc_card_set_bad(card);
                         return;
                 }
-
-                m = UNSTUFF_BITS(resp, 115, 4);
-                e = UNSTUFF_BITS(resp, 112, 3);
-                csd->tacc_ns     = (tacc_exp[e] * tacc_mant[m] + 9) / 10;
-                csd->tacc_clks   = UNSTUFF_BITS(resp, 104, 8) * 100;
-
-                m = UNSTUFF_BITS(resp, 99, 4);
-                e = UNSTUFF_BITS(resp, 96, 3);
-                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);
-
-                csd->read_blkbits = UNSTUFF_BITS(resp, 80, 4);
-                csd->read_partial = UNSTUFF_BITS(resp, 79, 1);
-                csd->write_misalign = UNSTUFF_BITS(resp, 78, 1);
-                csd->read_misalign = UNSTUFF_BITS(resp, 77, 1);
-                csd->r2w_factor = UNSTUFF_BITS(resp, 26, 3);
-                csd->write_blkbits = UNSTUFF_BITS(resp, 22, 4);
-                csd->write_partial = UNSTUFF_BITS(resp, 21, 1);
         } else {
                 /*
                  * We only understand CSD structure v1.1 and v1.2.
@@ -848,6 +882,41 @@ static int mmc_send_app_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr)
         return err;
 }
 
+static int mmc_send_if_cond(struct mmc_host *host, u32 ocr, int *rsd2)
+{
+        struct mmc_command cmd;
+        int err, sd2;
+        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 cards.
+        */
+        cmd.opcode = SD_SEND_IF_COND;
+        cmd.arg = ((ocr & 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) {
+                        sd2 = 1;
+                } else {
+                        sd2 = 0;
+                        err = MMC_ERR_FAILED;
+                }
+        } else {
+                /*
+                 * Treat errors as SD 1.0 card.
+                 */
+                sd2 = 0;
+                err = MMC_ERR_NONE;
+        }
+        if (rsd2)
+                *rsd2 = sd2;
+        return err;
+}
+
 /*
  * Discover cards by requesting their CID.  If this command
  * times out, it is not an error; there are no further cards
@@ -1334,6 +1403,10 @@ static void mmc_setup(struct mmc_host *host)
                 mmc_power_up(host);
                 mmc_idle_cards(host);
 
+                err = mmc_send_if_cond(host, host->ocr_avail, NULL);
+                if (err != MMC_ERR_NONE) {
+                        return;
+                }
                 err = mmc_send_app_op_cond(host, 0, &ocr);
 
                 /*
@@ -1386,10 +1459,21 @@ static void mmc_setup(struct mmc_host *host)
          * all get the idea that they should be ready for CMD2.
          * (My SanDisk card seems to need this.)
          */
-        if (host->mode == MMC_MODE_SD)
-                mmc_send_app_op_cond(host, host->ocr, NULL);
-        else
+        if (host->mode == MMC_MODE_SD) {
+                int err, sd2;
+                err = mmc_send_if_cond(host, host->ocr, &sd2);
+                if (err == MMC_ERR_NONE) {
+                        /*
+                        * If SD_SEND_IF_COND indicates an SD 2.0
+                        * compliant card and we should set bit 30
+                        * of the ocr to indicate that we can handle
+                        * block-addressed SDHC cards.
+                        */
+                        mmc_send_app_op_cond(host, host->ocr | (sd2 << 30), NULL);
+                }
+        } else {
                 mmc_send_op_cond(host, host->ocr, NULL);
+        }
 
         mmc_discover_cards(host);