mmc: support BKOPS feature for eMMC

Enable eMMC background operations (BKOPS) feature.

If URGENT_BKOPS is set after a response, note that BKOPS are required.
Immediately run BKOPS if required.  Read/write operations should be
requested during BKOPS(LEVEL-1), then issue HPI to interrupt the
ongoing BKOPS and service the foreground operation.
(This patch only controls the LEVEL2/3.)

When repeating the writing 1GB data, at a certain time, performance is
decreased.  At that time, card triggers the Level-3 or Level-2.  After
running bkops, performance is recovered.

Future considerations:
 * Check BKOPS_LEVEL=1 and start BKOPS in a preventive manner.
 * Interrupt ongoing BKOPS before powering off the card.
 * How do we get BKOPS_STATUS value (periodically send ext_csd command)?
 * If using periodic bkops, also consider runtime_pm control.

Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Konstantin Dorfman <kdorfman@codeaurora.org>
Reviewed-by: Maya Erez <merez@codeaurora.org>
Signed-off-by: Chris Ball <cjb@laptop.org>

1 files changed, 22 insertions, 4 deletions

diff --git a/drivers/mmc/core/mmc_ops.c b/drivers/mmc/core/mmc_ops.c
index 225371a28861..a0e172042e65 100644
--- a/drivers/mmc/core/mmc_ops.c
+++ b/drivers/mmc/core/mmc_ops.c
@@ -393,18 +393,19 @@ int mmc_spi_set_crc(struct mmc_host *host, int use_crc)
 }
 
 /**
- *      mmc_switch - modify EXT_CSD register
+ *      __mmc_switch - modify EXT_CSD register
  *      @card: the MMC card associated with the data transfer
  *      @set: cmd set values
  *      @index: EXT_CSD register index
  *      @value: value to program into EXT_CSD register
  *      @timeout_ms: timeout (ms) for operation performed by register write,
  *                   timeout of zero implies maximum possible timeout
+ *      @use_busy_signal: use the busy signal as response type
  *
  *      Modifies the EXT_CSD register for selected card.
  */
-int mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
-               unsigned int timeout_ms)
+int __mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
+               unsigned int timeout_ms, bool use_busy_signal)
 {
         int err;
         struct mmc_command cmd = {0};
@@ -418,13 +419,23 @@ int mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
                   (index << 16) |
                   (value << 8) |
                   set;
-        cmd.flags = MMC_RSP_SPI_R1B | MMC_RSP_R1B | MMC_CMD_AC;
+        cmd.flags = MMC_CMD_AC;
+        if (use_busy_signal)
+                cmd.flags |= MMC_RSP_SPI_R1B | MMC_RSP_R1B;
+        else
+                cmd.flags |= MMC_RSP_SPI_R1 | MMC_RSP_R1;
+
+
         cmd.cmd_timeout_ms = timeout_ms;
 
         err = mmc_wait_for_cmd(card->host, &cmd, MMC_CMD_RETRIES);
         if (err)
                 return err;
 
+        /* No need to check card status in case of unblocking command */
+        if (!use_busy_signal)
+                return 0;
+
         /* Must check status to be sure of no errors */
         do {
                 err = mmc_send_status(card, &status);
@@ -449,6 +460,13 @@ int mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
 
         return 0;
 }
+EXPORT_SYMBOL_GPL(__mmc_switch);
+
+int mmc_switch(struct mmc_card *card, u8 set, u8 index, u8 value,
+                unsigned int timeout_ms)
+{
+        return __mmc_switch(card, set, index, value, timeout_ms, true);
+}
 EXPORT_SYMBOL_GPL(mmc_switch);
 
 int mmc_send_status(struct mmc_card *card, u32 *status)