mmc: support unsafe resume of cards
Since many have the system root on MMC/SD we must allow some foot
shooting when it comes to resume.
We cannot detect if a card is removed and reinserted during suspend,
so the safe approach would be to assume it was, avoiding potential
filesystem corruption. This will of course not work if you cannot
release the card before suspend.
This commit adds a compile time option that makes the MMC layer
assume the card wasn't touched if it is redetected upon resume.
Signed-off-by: Pierre Ossman <drzeus@drzeus.cx>
diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
index ae54e8e..6597e77 100644
--- a/drivers/mmc/core/sd.c
+++ b/drivers/mmc/core/sd.c
@@ -263,6 +263,161 @@
}
/*
+ * Handle the detection and initialisation of a card.
+ *
+ * In the case of a resume, "curcard" will contain the card
+ * we're trying to reinitialise.
+ */
+static int mmc_sd_init_card(struct mmc_host *host, u32 ocr,
+ struct mmc_card *oldcard)
+{
+ struct mmc_card *card;
+ int err;
+ u32 cid[4];
+ unsigned int max_dtr;
+
+ BUG_ON(!host);
+ BUG_ON(!host->claimed);
+
+ /*
+ * Since we're changing the OCR value, we seem to
+ * need to tell some cards to go back to the idle
+ * state. We wait 1ms to give cards time to
+ * respond.
+ */
+ mmc_go_idle(host);
+
+ /*
+ * If SD_SEND_IF_COND indicates an SD 2.0
+ * compliant card and we should set bit 30
+ * of the ocr to indicate that we can handle
+ * block-addressed SDHC cards.
+ */
+ err = mmc_send_if_cond(host, ocr);
+ if (err == MMC_ERR_NONE)
+ ocr |= 1 << 30;
+
+ err = mmc_send_app_op_cond(host, ocr, NULL);
+ if (err != MMC_ERR_NONE)
+ goto err;
+
+ /*
+ * Fetch CID from card.
+ */
+ err = mmc_all_send_cid(host, cid);
+ if (err != MMC_ERR_NONE)
+ goto err;
+
+ if (oldcard) {
+ if (memcmp(cid, oldcard->raw_cid, sizeof(cid)) != 0)
+ goto err;
+
+ card = oldcard;
+ } else {
+ /*
+ * Allocate card structure.
+ */
+ card = mmc_alloc_card(host);
+ if (IS_ERR(card))
+ goto err;
+
+ card->type = MMC_TYPE_SD;
+ memcpy(card->raw_cid, cid, sizeof(card->raw_cid));
+ }
+
+ /*
+ * Set card RCA.
+ */
+ err = mmc_send_relative_addr(host, &card->rca);
+ if (err != MMC_ERR_NONE)
+ goto free_card;
+
+ mmc_set_bus_mode(host, MMC_BUSMODE_PUSHPULL);
+
+ if (!oldcard) {
+ /*
+ * Fetch CSD from card.
+ */
+ err = mmc_send_csd(card, card->raw_csd);
+ if (err != MMC_ERR_NONE)
+ goto free_card;
+
+ mmc_decode_csd(card);
+ mmc_decode_cid(card);
+ }
+
+ /*
+ * Select card, as all following commands rely on that.
+ */
+ err = mmc_select_card(card);
+ if (err != MMC_ERR_NONE)
+ goto free_card;
+
+ if (!oldcard) {
+ /*
+ * Fetch SCR from card.
+ */
+ err = mmc_app_send_scr(card, card->raw_scr);
+ if (err != MMC_ERR_NONE)
+ goto free_card;
+
+ mmc_decode_scr(card);
+
+ /*
+ * Fetch switch information from card.
+ */
+ err = mmc_read_switch(card);
+ if (err != MMC_ERR_NONE)
+ goto free_card;
+ }
+
+ /*
+ * Attempt to change to high-speed (if supported)
+ */
+ err = mmc_switch_hs(card);
+ if (err != MMC_ERR_NONE)
+ goto free_card;
+
+ /*
+ * Compute bus speed.
+ */
+ max_dtr = (unsigned int)-1;
+
+ if (mmc_card_highspeed(card)) {
+ if (max_dtr > card->sw_caps.hs_max_dtr)
+ max_dtr = card->sw_caps.hs_max_dtr;
+ } else if (max_dtr > card->csd.max_dtr) {
+ max_dtr = card->csd.max_dtr;
+ }
+
+ mmc_set_clock(host, max_dtr);
+
+ /*
+ * Switch to wider bus (if supported).
+ */
+ if ((host->caps && MMC_CAP_4_BIT_DATA) &&
+ (card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
+ err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
+ if (err != MMC_ERR_NONE)
+ goto free_card;
+
+ mmc_set_bus_width(host, MMC_BUS_WIDTH_4);
+ }
+
+ if (!oldcard)
+ host->card = card;
+
+ return MMC_ERR_NONE;
+
+free_card:
+ if (!oldcard)
+ mmc_remove_card(card);
+err:
+
+ return MMC_ERR_FAILED;
+}
+
+/*
* Host is being removed. Free up the current card.
*/
static void mmc_sd_remove(struct mmc_host *host)
@@ -303,9 +458,60 @@
}
}
+#ifdef CONFIG_MMC_UNSAFE_RESUME
+
+/*
+ * Suspend callback from host.
+ */
+static void mmc_sd_suspend(struct mmc_host *host)
+{
+ BUG_ON(!host);
+ BUG_ON(!host->card);
+
+ mmc_claim_host(host);
+ mmc_deselect_cards(host);
+ host->card->state &= ~MMC_STATE_HIGHSPEED;
+ mmc_release_host(host);
+}
+
+/*
+ * Resume callback from host.
+ *
+ * This function tries to determine if the same card is still present
+ * and, if so, restore all state to it.
+ */
+static void mmc_sd_resume(struct mmc_host *host)
+{
+ int err;
+
+ BUG_ON(!host);
+ BUG_ON(!host->card);
+
+ mmc_claim_host(host);
+
+ err = mmc_sd_init_card(host, host->ocr, host->card);
+ if (err != MMC_ERR_NONE) {
+ mmc_remove_card(host->card);
+ host->card = NULL;
+
+ mmc_detach_bus(host);
+ }
+
+ mmc_release_host(host);
+}
+
+#else
+
+#define mmc_sd_suspend NULL
+#define mmc_sd_resume NULL
+
+#endif
+
static const struct mmc_bus_ops mmc_sd_ops = {
.remove = mmc_sd_remove,
.detect = mmc_sd_detect,
+ .suspend = mmc_sd_suspend,
+ .resume = mmc_sd_resume,
};
/*
@@ -313,10 +519,7 @@
*/
int mmc_attach_sd(struct mmc_host *host, u32 ocr)
{
- struct mmc_card *card;
int err;
- u32 cid[4];
- unsigned int max_dtr;
BUG_ON(!host);
BUG_ON(!host->claimed);
@@ -350,119 +553,15 @@
goto err;
/*
- * Since we're changing the OCR value, we seem to
- * need to tell some cards to go back to the idle
- * state. We wait 1ms to give cards time to
- * respond.
+ * Detect and init the card.
*/
- mmc_go_idle(host);
-
- /*
- * If SD_SEND_IF_COND indicates an SD 2.0
- * compliant card and we should set bit 30
- * of the ocr to indicate that we can handle
- * block-addressed SDHC cards.
- */
- err = mmc_send_if_cond(host, host->ocr);
- if (err == MMC_ERR_NONE)
- ocr = host->ocr | (1 << 30);
-
- mmc_send_app_op_cond(host, ocr, NULL);
-
- /*
- * Fetch CID from card.
- */
- err = mmc_all_send_cid(host, cid);
+ err = mmc_sd_init_card(host, host->ocr, NULL);
if (err != MMC_ERR_NONE)
goto err;
- /*
- * Allocate card structure.
- */
- card = mmc_alloc_card(host);
- if (IS_ERR(card))
- goto err;
-
- card->type = MMC_TYPE_SD;
- memcpy(card->raw_cid, cid, sizeof(card->raw_cid));
-
- /*
- * Set card RCA.
- */
- err = mmc_send_relative_addr(host, &card->rca);
- if (err != MMC_ERR_NONE)
- goto free_card;
-
- mmc_set_bus_mode(host, MMC_BUSMODE_PUSHPULL);
-
- /*
- * Fetch CSD from card.
- */
- err = mmc_send_csd(card, card->raw_csd);
- if (err != MMC_ERR_NONE)
- goto free_card;
-
- mmc_decode_csd(card);
- mmc_decode_cid(card);
-
- /*
- * Fetch SCR from card.
- */
- err = mmc_select_card(card);
- if (err != MMC_ERR_NONE)
- goto free_card;
-
- err = mmc_app_send_scr(card, card->raw_scr);
- if (err != MMC_ERR_NONE)
- goto free_card;
-
- mmc_decode_scr(card);
-
- /*
- * Fetch switch information from card.
- */
- err = mmc_read_switch(card);
- if (err != MMC_ERR_NONE)
- goto free_card;
-
- /*
- * Attempt to change to high-speed (if supported)
- */
- err = mmc_switch_hs(card);
- if (err != MMC_ERR_NONE)
- goto free_card;
-
- /*
- * Compute bus speed.
- */
- max_dtr = (unsigned int)-1;
-
- if (mmc_card_highspeed(card)) {
- if (max_dtr > card->sw_caps.hs_max_dtr)
- max_dtr = card->sw_caps.hs_max_dtr;
- } else if (max_dtr > card->csd.max_dtr) {
- max_dtr = card->csd.max_dtr;
- }
-
- mmc_set_clock(host, max_dtr);
-
- /*
- * Switch to wider bus (if supported).
- */
- if ((host->caps && MMC_CAP_4_BIT_DATA) &&
- (card->scr.bus_widths & SD_SCR_BUS_WIDTH_4)) {
- err = mmc_app_set_bus_width(card, MMC_BUS_WIDTH_4);
- if (err != MMC_ERR_NONE)
- goto free_card;
-
- mmc_set_bus_width(host, MMC_BUS_WIDTH_4);
- }
-
- host->card = card;
-
mmc_release_host(host);
- err = mmc_register_card(card);
+ err = mmc_register_card(host->card);
if (err)
goto reclaim_host;
@@ -470,8 +569,7 @@
reclaim_host:
mmc_claim_host(host);
-free_card:
- mmc_remove_card(card);
+ mmc_remove_card(host->card);
host->card = NULL;
err:
mmc_detach_bus(host);