mmc: Introduce mmc_send_stop_transmission()

If a tuning command times out, the card could still be processing it,
which will cause problems for recovery. The eMMC specification section
6.6 Data transfer mode (cont’d) claims that CMD12 can be used to stop
CMD21:
"
The relationship between the various data transfer modes is summarized (see Figure 27):
- All data read commands can be aborted any time by the stop command (CMD12).
  The data transfer will terminate and the Device will return to the Transfer State.
  The read commands are: ... send tuning block (CMD21) ....
"
Add a function that does that.

Based on Linux commit [1] and [2].

[1] e711f0309109 ("mmc: mmc: Introduce mmc_abort_tuning()")
[2] 21adc2e45f4e ("mmc: Improve function name when aborting a tuning
cmd")

Reviewed-by: Takeshi Kihara <takeshi.kihara.df@renesas.com>
Reviewed-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Signed-off-by: Hai Pham <hai.pham.ud@renesas.com>
Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
[Marek: Update commit message, quote relevant part of the specification.
        Rename to mmc_send_stop_transmission().
	Remove tuning opcode check, this is controller driver specific.
	Deduplicate part of mmc_read_blocks() using this function.]
Reviewed-by:  Peng Fan <peng.fan@nxp.com>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/mmc.h b/include/mmc.h
index b8fbff150de..1022db3ffa7 100644
--- a/include/mmc.h
+++ b/include/mmc.h
@@ -558,6 +558,8 @@ int mmc_deferred_probe(struct mmc *mmc);
 int mmc_reinit(struct mmc *mmc);
 int mmc_get_b_max(struct mmc *mmc, void *dst, lbaint_t blkcnt);
 int mmc_hs400_prepare_ddr(struct mmc *mmc);
+int mmc_send_stop_transmission(struct mmc *mmc, bool write);
+
 #else
 struct mmc_ops {
 	int (*send_cmd)(struct mmc *mmc,