mmc: block: support no access to boot partitions

Intel Medfield platform blocks access to eMMC boot partitions which
results in switch errors.  Since there is no access, mmcboot0/1
devices should not be created.  Add a host capability to reflect that.
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/card/block.c

@@ -1480,7 +1480,7 @@ static int mmc_blk_alloc_parts(struct mmc_card *card, struct mmc_blk_data *md)
 	if (!mmc_card_mmc(card))
 		return 0;
 
-	if (card->ext_csd.boot_size) {
+	if (card->ext_csd.boot_size && mmc_boot_partition_access(card->host)) {
 		ret = mmc_blk_alloc_part(card, md, EXT_CSD_PART_CONFIG_ACC_BOOT0,
 					 card->ext_csd.boot_size >> 9,
 					 true,

drivers/mmc/host/sdhci-pci.c

@@ -215,6 +215,8 @@ static int mfd_emmc_probe_slot(struct sdhci_pci_slot *slot)
 
 	slot->host->mmc->caps |= MMC_CAP_8_BIT_DATA;
 
+	slot->host->mmc->caps2 = MMC_CAP2_BOOTPART_NOACC;
+
 	return 0;
 }
 

include/linux/mmc/host.h

@@ -236,6 +236,10 @@ struct mmc_host {
 #define MMC_CAP_CMD23		(1 << 30)	/* CMD23 supported. */
 #define MMC_CAP_HW_RESET	(1 << 31)	/* Hardware reset */
 
+	unsigned int		caps2;		/* More host capabilities */
+
+#define MMC_CAP2_BOOTPART_NOACC	(1 << 0)	/* Boot partition no access */
+
 	mmc_pm_flag_t		pm_caps;	/* supported pm features */
 
 #ifdef CONFIG_MMC_CLKGATE
@@ -404,4 +408,10 @@ static inline int mmc_host_cmd23(struct mmc_host *host)
 {
 	return host->caps & MMC_CAP_CMD23;
 }
+
+static inline int mmc_boot_partition_access(struct mmc_host *host)
+{
+	return !(host->caps2 & MMC_CAP2_BOOTPART_NOACC);
+}
+
 #endif /* LINUX_MMC_HOST_H */