sf: Make 4K sector support configurable

Make the support for 4K subpage I/O on a SPI NOR flash configurable.
A board which requires the SPI NOR to be accessed in larger 32KiB
or 64KiB pages can disable the 4K subpage support, but by default,
the support for 4K subpage I/O is enabled. The functionality of this
option is the same as CONFIG_MTD_SPI_NOR_USE_4K_SECTORS in Linux.

This is extremely useful in case one uses UBI on a SPI NOR flash.
UBI needs at least 15k EBs and can not work on a flash which uses
4k ones, so disabling the support for 4k subpages lets UBI work on
such flash.

Signed-off-by: Marek Vasut <marex@denx.de>
Reviewed-by: Jagan Teki <jteki@openedev.com>

diff --git a/drivers/mtd/spi/Kconfig b/drivers/mtd/spi/Kconfig
index 8b730ff3c55458b5040e5891adcdeab6012948b7..3f7433cbc214b76a7120886f858047d64b51744c 100644 (file)
--- a/drivers/mtd/spi/Kconfig
+++ b/drivers/mtd/spi/Kconfig
@@ -86,6 +86,21 @@ config SPI_FLASH_WINBOND
 
 endif
 
+config SPI_FLASH_USE_4K_SECTORS
+       bool "Use small 4096 B erase sectors"
+       depends on SPI_FLASH
+       default y
+       help
+         Many flash memories support erasing small (4096 B) sectors. Depending
+         on the usage this feature may provide performance gain in comparison
+         to erasing whole blocks (32/64 KiB).
+         Changing a small part of the flash's contents is usually faster with
+         small sectors. On the other hand erasing should be faster when using
+         64 KiB block instead of 16 × 4 KiB sectors.
+
+         Please note that some tools/drivers/filesystems may not work with
+         4096 B erase size (e.g. UBIFS requires 15 KiB as a minimum).
+
 config SPI_FLASH_DATAFLASH
        bool "AT45xxx DataFlash support"
        depends on SPI_FLASH && DM_SPI_FLASH

diff --git a/drivers/mtd/spi/sf_internal.h b/drivers/mtd/spi/sf_internal.h
index 9fb555707cdeca8ca2c4e56e204053210a48d76a..9c95d5616eb6b3bb0c0f954001e6656b8941faf9 100644 (file)
--- a/drivers/mtd/spi/sf_internal.h
+++ b/drivers/mtd/spi/sf_internal.h
@@ -37,7 +37,11 @@ enum spi_read_cmds {
 
 /* sf param flags */
 enum {
+#ifdef CONFIG_SPI_FLASH_USE_4K_SECTORS
        SECT_4K         = 1 << 0,
+#else
+       SECT_4K         = 0 << 0,
+#endif
        SECT_32K        = 1 << 1,
        E_FSR           = 1 << 2,
        SST_BP          = 1 << 3,