From 90c08fa038451d6d7b7d8711bfd829b61d64c490 Mon Sep 17 00:00:00 2001 From: Michael Pratt Date: Mon, 11 Jun 2018 13:07:09 -0600 Subject: fdt: Add device tree memory bindings Support a default memory bank, specified in reg, as well as board-specific memory banks in subtree board-id nodes. This allows memory information to be provided in the device tree, rather than hard-coded in, which will make it simpler to handle similar devices with different memory banks, as the board-id values or masks can be used to match devices. Signed-off-by: Michael Pratt Signed-off-by: Simon Glass Reviewed-by: Vadim Bendebury --- include/fdtdec.h | 38 +++++++++++++++++++++++++++++++++++++- 1 file changed, 37 insertions(+), 1 deletion(-) (limited to 'include/fdtdec.h') diff --git a/include/fdtdec.h b/include/fdtdec.h index c15b2a04a7..332105504b 100644 --- a/include/fdtdec.h +++ b/include/fdtdec.h @@ -41,6 +41,8 @@ struct fdt_memory { fdt_addr_t end; }; +struct bd_info; + #ifdef CONFIG_SPL_BUILD #define SPL_BUILD 1 #else @@ -993,6 +995,40 @@ int fdtdec_setup(void); * Called when CONFIG_OF_BOARD is defined, or if CONFIG_OF_SEPARATE is defined * and the board implements it. */ -void *board_fdt_blob_setup(void); + +/* + * Decode the size of memory + * + * RAM size is normally set in a /memory node and consists of a list of + * (base, size) cells in the 'reg' property. This information is used to + * determine the total available memory as well as the address and size + * of each bank. + * + * Optionally the memory configuration can vary depending on a board id, + * typically read from strapping resistors or an EEPROM on the board. + * + * Finally, memory size can be detected (within certain limits) by probing + * the available memory. It is safe to do so within the limits provides by + * the board's device tree information. This makes it possible to produce + * boards with different memory sizes, where the device tree specifies the + * maximum memory configuration, and the smaller memory configuration is + * probed. + * + * This function decodes that information, returning the memory base address, + * size and bank information. See the memory.txt binding for full + * documentation. + * + * @param blob Device tree blob + * @param area Name of node to check (NULL means "/memory") + * @param board_id Board ID to look up + * @param basep Returns base address of first memory bank (NULL to + * ignore) + * @param sizep Returns total memory size (NULL to ignore) + * @param bd Updated with the memory bank information (NULL to skip) + * @return 0 if OK, -ve on error + */ +int fdtdec_decode_ram_size(const void *blob, const char *area, int board_id, + phys_addr_t *basep, phys_size_t *sizep, + struct bd_info *bd); #endif -- cgit