mmc: core: Add cache control for eMMC4.5 device

This patch adds cache feature of eMMC4.5 Spec.
If device supports cache capability, host can utilize some specific
operations.

Signed-off-by: Seungwon Jeon <tgih.jun@samsung.com>
Signed-off-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

3 files changed, 94 insertions, 6 deletions

diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
index 370472797fff..c0cb225bbb47 100644
--- a/drivers/mmc/card/block.c
+++ b/drivers/mmc/card/block.c
@@ -851,16 +851,18 @@ out:
 static int mmc_blk_issue_flush(struct mmc_queue *mq, struct request *req)
 {
         struct mmc_blk_data *md = mq->data;
+        struct mmc_card *card = md->queue.card;
+        int ret = 0;
+
+        ret = mmc_flush_cache(card);
+        if (ret)
+                ret = -EIO;
 
-        /*
-         * No-op, only service this because we need REQ_FUA for reliable
-         * writes.
-         */
         spin_lock_irq(&md->lock);
-        __blk_end_request_all(req, 0);
+        __blk_end_request_all(req, ret);
         spin_unlock_irq(&md->lock);
 
-        return 1;
+        return ret ? 0 : 1;
 }
 
 /*
diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
index 772de2cdfd1d..235bb6a1f973 100644
--- a/drivers/mmc/core/core.c
+++ b/drivers/mmc/core/core.c
@@ -2158,6 +2158,65 @@ int mmc_card_can_sleep(struct mmc_host *host)
 }
 EXPORT_SYMBOL(mmc_card_can_sleep);
 
+/*
+ * Flush the cache to the non-volatile storage.
+ */
+int mmc_flush_cache(struct mmc_card *card)
+{
+        struct mmc_host *host = card->host;
+        int err = 0;
+
+        if (!(host->caps2 & MMC_CAP2_CACHE_CTRL))
+                return err;
+
+        if (mmc_card_mmc(card) &&
+                        (card->ext_csd.cache_size > 0) &&
+                        (card->ext_csd.cache_ctrl & 1)) {
+                err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+                                EXT_CSD_FLUSH_CACHE, 1, 0);
+                if (err)
+                        pr_err("%s: cache flush error %d\n",
+                                        mmc_hostname(card->host), err);
+        }
+
+        return err;
+}
+EXPORT_SYMBOL(mmc_flush_cache);
+
+/*
+ * Turn the cache ON/OFF.
+ * Turning the cache OFF shall trigger flushing of the data
+ * to the non-volatile storage.
+ */
+int mmc_cache_ctrl(struct mmc_host *host, u8 enable)
+{
+        struct mmc_card *card = host->card;
+        int err = 0;
+
+        if (!(host->caps2 & MMC_CAP2_CACHE_CTRL) ||
+                        mmc_card_is_removable(host))
+                return err;
+
+        if (card && mmc_card_mmc(card) &&
+                        (card->ext_csd.cache_size > 0)) {
+                enable = !!enable;
+
+                if (card->ext_csd.cache_ctrl ^ enable)
+                        err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+                                        EXT_CSD_CACHE_CTRL, enable, 0);
+                if (err)
+                        pr_err("%s: cache %s error %d\n",
+                                        mmc_hostname(card->host),
+                                        enable ? "on" : "off",
+                                        err);
+                else
+                        card->ext_csd.cache_ctrl = enable;
+        }
+
+        return err;
+}
+EXPORT_SYMBOL(mmc_cache_ctrl);
+
 #ifdef CONFIG_PM
 
 /**
@@ -2172,6 +2231,9 @@ int mmc_suspend_host(struct mmc_host *host)
                 cancel_delayed_work(&host->disable);
         cancel_delayed_work(&host->detect);
         mmc_flush_scheduled_work();
+        err = mmc_cache_ctrl(host, 0);
+        if (err)
+                goto out;
 
         mmc_bus_get(host);
         if (host->bus_ops && !host->bus_dead) {
@@ -2197,6 +2259,7 @@ int mmc_suspend_host(struct mmc_host *host)
         if (!err && !mmc_card_keep_power(host))
                 mmc_power_off(host);
 
+out:
         return err;
 }
 
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index 793901519208..de5900aa81cd 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -470,6 +470,12 @@ static int mmc_read_ext_csd(struct mmc_card *card, u8 *ext_csd)
         } else
                 card->ext_csd.generic_cmd6_time = 0;
 
+        card->ext_csd.cache_size =
+                ext_csd[EXT_CSD_CACHE_SIZE + 0] << 0 |
+                ext_csd[EXT_CSD_CACHE_SIZE + 1] << 8 |
+                ext_csd[EXT_CSD_CACHE_SIZE + 2] << 16 |
+                ext_csd[EXT_CSD_CACHE_SIZE + 3] << 24;
+
 out:
         return err;
 }
@@ -1020,6 +1026,23 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
                 }
         }
 
+        /*
+         * If cache size is higher than 0, this indicates
+         * the existence of cache and it can be turned on.
+         */
+        if ((host->caps2 & MMC_CAP2_CACHE_CTRL) &&
+                        card->ext_csd.cache_size > 0) {
+                err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+                                EXT_CSD_CACHE_CTRL, 1, 0);
+                if (err && err != -EBADMSG)
+                        goto free_card;
+
+                /*
+                 * Only if no error, cache is turned on successfully.
+                 */
+                card->ext_csd.cache_ctrl = err ? 0 : 1;
+        }
+
         if (!oldcard)
                 host->card = card;