From 19dbffd010af7713156ccfeecd019a6e8eedefaf Mon Sep 17 00:00:00 2001 From: Subrata Banik Date: Sun, 10 Sep 2017 20:06:22 +0530 Subject: arch/x86: Add ebda read/write functions into EBDA library This patch provides new APIs to write into EBDA area and read from EBDA area based on user input structure. Change-Id: I26d5c0ba82c842f0b734a8e0f03abf148737c5c4 Signed-off-by: Subrata Banik Reviewed-on: https://review.coreboot.org/21536 Tested-by: build bot (Jenkins) Reviewed-by: Aaron Durbin Reviewed-by: Sumeet R Pawnikar --- src/arch/x86/ebda.c | 59 +++++++++++++++++++++++++++++++++++++++- src/arch/x86/include/arch/ebda.h | 20 ++++++++++++++ 2 files changed, 78 insertions(+), 1 deletion(-) (limited to 'src/arch') diff --git a/src/arch/x86/ebda.c b/src/arch/x86/ebda.c index c828aa4f76..ba02e50401 100644 --- a/src/arch/x86/ebda.c +++ b/src/arch/x86/ebda.c @@ -20,6 +20,63 @@ #include #include #include +#include + +static void *get_ebda_start(void) +{ + return (void *)((uintptr_t)DEFAULT_EBDA_SEGMENT << 4); +} + +static bool is_length_valid(size_t dlength) +{ + /* Check if input data length is > DEFAULT_EBDA_SIZE */ + if (dlength > DEFAULT_EBDA_SIZE) + return false; + + /* Valid data length */ + return true; +} + +/* + * EBDA area is representing a 1KB memory area just below + * the top of conventional memory (below 1MB) + */ + +/* + * write_ebda_data is a wrapper function to write into EBDA area + * + * data = data to be written into EBDA area + * length = input data size. + */ +void write_ebda_data(const void *data, size_t length) +{ + void *ebda; + + if (!is_length_valid(length)) + die("Input data length is > EBDA default size (1KiB)!"); + + ebda = get_ebda_start(); + + memcpy(ebda, data, length); +} + +/* + * read_ebda_data is a wrapper function to read from EBDA area + * + * data = data read from EBDA area based on input size + * length = read data size. + */ +void read_ebda_data(void *data, size_t length) +{ + void *ebda; + + if (!is_length_valid(length)) + die("Input data length is > EBDA default size (1KiB)!"); + + ebda = get_ebda_start(); + + memcpy(data, ebda, length); +} void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size) { @@ -36,7 +93,7 @@ void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size) low_memory_kb = low_memory_size >> 10; ebda_kb = ebda_size >> 10; - ebda = (void *)((uintptr_t)ebda_segment << 4); + ebda = get_ebda_start(); /* clear BIOS DATA AREA */ zero_n(X86_BDA_BASE, X86_BDA_SIZE); diff --git a/src/arch/x86/include/arch/ebda.h b/src/arch/x86/include/arch/ebda.h index 428bc92c27..2347ea5318 100644 --- a/src/arch/x86/include/arch/ebda.h +++ b/src/arch/x86/include/arch/ebda.h @@ -32,4 +32,24 @@ void setup_ebda(u32 low_memory_size, u16 ebda_segment, u16 ebda_size); void setup_default_ebda(void); +/* + * This read/write API only allows and assumes + * a single EBDA structure type for a platform. + */ + +/* + * write_ebda_data is a wrapper function to write into EBDA area + * + * data = data to be written into EBDA area + * length = input data size. + */ +void write_ebda_data(const void *data, size_t length); +/* + * read_ebda_data is a wrapper function to read from EBDA area + * + * data = data read from EBDA area based on input size + * length = read data size. + */ +void read_ebda_data(void *data, size_t length); + #endif -- cgit v1.2.3