Add support for an SDIO device to stay powered off even without
the presence of an SDIO function driver. A host should explicitly
ask for it by means of MMC_CAP_DONT_POWER_CARD, and the SDIO
function driver should know it needs to call sdio_claim_power
before accessing the device.
Signed-off-by: Ohad Ben-Cohen <ohad@xxxxxxxxxx>
---
drivers/mmc/core/sdio.c | 15 +++++++++++++--
include/linux/mmc/host.h | 1 +
2 files changed, 14 insertions(+), 2 deletions(-)
diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 5c0fbfa..164353f 100644
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -80,8 +80,9 @@ static int sdio_init_func(struct mmc_card *card, unsigned int fn)
return ret;
/* For each SDIO function initialized, increase the power claim
- * reference count of the card */
- atomic_inc(&card->power_claims);
+ * reference count of the card, unless explicitly requested not to */
+ if (!(card->host->caps & MMC_CAP_DONT_POWER_CARD))
+ atomic_inc(&card->power_claims);
return 0;
@@ -607,6 +608,16 @@ int mmc_attach_sdio(struct mmc_host *host, u32 ocr)
mmc_release_host(host);
/*
+ * If power is not required for this card, power it off.
+ * The sdio function will need to call sdio_claim_power.
+ */
+ if (!atomic_read(&card->power_claims)) {
+ pr_info("%s: power is not claimed, releasing\n",
+ mmc_hostname(host));
+ mmc_release_power(host);
+ }
+
+ /*
* First add the card to the driver model...
*/
err = mmc_add_card(host->card);
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 3675d58..756cf38 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -155,6 +155,7 @@ struct mmc_host {
#define MMC_CAP_DISABLE (1 << 7) /* Can the host be disabled */
#define MMC_CAP_NONREMOVABLE (1 << 8) /* Nonremovable e.g. eMMC */
#define MMC_CAP_WAIT_WHILE_BUSY (1 << 9) /* Waits while card is busy */
+#define MMC_CAP_DONT_POWER_CARD (1 << 10) /* Keep the card powered off */
mmc_pm_flag_t pm_caps; /* supported pm features */
--
1.7.0.4
--
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