mmc: Add per-card debugfs support

For each card successfully added to the bus, create a subdirectory under
the host's debugfs root with information about the card.

At the moment, only a single file is added to the card directory for
all cards: "state". It reflects the "state" field in struct mmc_card,
indicating whether the card is present, readonly, etc.

For MMC and SD cards (not SDIO), another file is added: "status".
Reading this file will ask the card about its current status and
return it. This can be useful if the card just refuses to respond to
any commands, which might indicate that the card state is not what the
MMC core thinks it is (due to a missing stop command, for example.)

Signed-off-by: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 0d508ac17d64..ee6e822d5994 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -111,6 +111,8 @@ struct mmc_card {
         unsigned                num_info;       /* number of info strings */
         const char              **info;         /* info strings */
         struct sdio_func_tuple  *tuples;        /* unknown common tuples */
+
+        struct dentry           *debugfs_root;
 };
 
 #define mmc_card_mmc(c)         ((c)->type == MMC_TYPE_MMC)