[PATCH] mmc: Support 32-bit only ADMA on 64-bit platforms

[Greg Malysa]

Some arm64 platforms may include SDIO host controllers that
only support 32-bit ADMA. While the Linux kernel detects which
size is supported and adjusts the descriptor size used dynamically,
the previous u-boot implementation statically selected between the
two depending on whether DMA_ADDR_T_64BIT was defined. Because the
static selection is already in place and effective for most platforms,
this patch logically separates "64 bit addresses are used for DMA on
this platform" and "64 bit addresses are used by the SDIO host
controller for ADMA" in order to support the small number of platforms
where these statements are not equivalent.

Using 32 bits is opt-in and existing 64 bit platforms should be
unaffected by this change.

Co-developed-by: Nathan Barrett-Morrison <nathan.morrison at timesys.com>
Signed-off-by: Nathan Barrett-Morrison <nathan.morrison at timesys.com>
Co-developed-by: Ian Roberts <ian.roberts at timesys.com>
Signed-off-by: Ian Roberts <ian.roberts at timesys.com>
Signed-off-by: Greg Malysa <greg.malysa at timesys.com>

---


---
 drivers/mmc/Kconfig      | 18 ++++++++++++++++++
 drivers/mmc/sdhci-adma.c |  2 +-
 drivers/mmc/sdhci.c      |  9 ++++-----
 include/sdhci.h          |  4 ++--
 4 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
index cef05790dd..4538286c64 100644
--- a/drivers/mmc/Kconfig
+++ b/drivers/mmc/Kconfig
@@ -495,6 +495,24 @@ config SPL_MMC_SDHCI_ADMA
 	  This enables support for the ADMA (Advanced DMA) defined
 	  in the SD Host Controller Standard Specification Version 3.00 in SPL.
 
+config MMC_SDHCI_ADMA_FORCE_32BIT
+	bool "Force 32 bit mode for ADMA on 64 bit platforms"
+	help
+	  This forces SDHCI ADMA to be built for 32 bit descriptors, even
+	  on a 64 bit platform where they would otherwise be assumed to
+	  be 64 bits. This is necessary for certain hardware platforms
+	  that are 64-bit but include only 32-bit support within the selected
+	  SD host controller IP.
+
+config MMC_SDHCI_ADMA_64BIT
+	bool "Use SHDCI ADMA with 64 bit descriptors"
+	depends on !MMC_SDHCI_ADMA_FORCE_32BIT
+	default y if DMA_ADDR_T_64BIT
+	help
+	  This selects 64 bit descriptors for SDHCI ADMA. It is enabled by
+	  default on 64 bit systems, but can be disabled if one of these
+	  systems includes 32-bit ADMA.
+
 config FIXED_SDHCI_ALIGNED_BUFFER
 	hex "SDRAM address for fixed buffer"
 	depends on SPL && MVEBU_SPL_BOOT_DEVICE_MMC
diff --git a/drivers/mmc/sdhci-adma.c b/drivers/mmc/sdhci-adma.c
index 8213223d3f..474647c3fd 100644
--- a/drivers/mmc/sdhci-adma.c
+++ b/drivers/mmc/sdhci-adma.c
@@ -22,7 +22,7 @@ static void sdhci_adma_desc(struct sdhci_adma_desc *desc,
 	desc->len = len;
 	desc->reserved = 0;
 	desc->addr_lo = lower_32_bits(addr);
-#ifdef CONFIG_DMA_ADDR_T_64BIT
+#ifdef CONFIG_MMC_SDHCI_ADMA_64BIT
 	desc->addr_hi = upper_32_bits(addr);
 #endif
 }
diff --git a/drivers/mmc/sdhci.c b/drivers/mmc/sdhci.c
index 0178ed8a11..b27ce57d96 100644
--- a/drivers/mmc/sdhci.c
+++ b/drivers/mmc/sdhci.c
@@ -900,11 +900,10 @@ int sdhci_setup_cfg(struct mmc_config *cfg, struct sdhci_host *host,
 	host->adma_desc_table = sdhci_adma_init();
 	host->adma_addr = (dma_addr_t)host->adma_desc_table;
 
-#ifdef CONFIG_DMA_ADDR_T_64BIT
-	host->flags |= USE_ADMA64;
-#else
-	host->flags |= USE_ADMA;
-#endif
+	if (IS_ENABLED(CONFIG_MMC_SDHCI_ADMA_64BIT))
+		host->flags |= USE_ADMA64;
+	else
+		host->flags |= USE_ADMA;
 #endif
 	if (host->quirks & SDHCI_QUIRK_REG32_RW)
 		host->version =
diff --git a/include/sdhci.h b/include/sdhci.h
index a1b74e3bd7..07b84d6715 100644
--- a/include/sdhci.h
+++ b/include/sdhci.h
@@ -294,7 +294,7 @@ struct sdhci_ops {
 };
 
 #define ADMA_MAX_LEN	65532
-#ifdef CONFIG_DMA_ADDR_T_64BIT
+#ifdef CONFIG_MMC_SDHCI_ADMA_64BIT
 #define ADMA_DESC_LEN	16
 #else
 #define ADMA_DESC_LEN	8
@@ -319,7 +319,7 @@ struct sdhci_adma_desc {
 	u8 reserved;
 	u16 len;
 	u32 addr_lo;
-#ifdef CONFIG_DMA_ADDR_T_64BIT
+#ifdef CONFIG_MMC_SDHCI_ADMA_64BIT
 	u32 addr_hi;
 #endif
 } __packed;
-- 
2.43.2