mmc: Add .multi_io_quirk callback for multi I/O HW bug

Historically, we have been using MMC_CAP* to handle host HW issues and
currently the block layer uses MMC_CAP2_NO_MULTI_READ flag for a multi
I/O HW bug workaround.

There are a few tweaks needed to make MMC_CAP2_NO_MULTI_READ suite all
situations. Therefore let's add an optional host ops callback to enable
host drivers to return the number of blocks it allows per request.

In a future patch and when host drivers have converted to the new
callback, MMC_CAP2_NO_MULTI_READ shall be removed.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 4cbf61476999..10e2bd6985ae 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -139,6 +139,13 @@ struct mmc_host_ops {
         int     (*select_drive_strength)(unsigned int max_dtr, int host_drv, int card_drv);
         void    (*hw_reset)(struct mmc_host *host);
         void    (*card_event)(struct mmc_host *host);
+
+        /*
+         * Optional callback to support controllers with HW issues for multiple
+         * I/O. Returns the number of supported blocks for the request.
+         */
+        int     (*multi_io_quirk)(struct mmc_card *card,
+                                  unsigned int direction, int blk_size);
 };
 
 struct mmc_card;