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authorSubrata Banik <subrata.banik@intel.com>2017-09-10 20:06:22 +0530
committerAaron Durbin <adurbin@chromium.org>2017-09-22 15:29:38 +0000
commit19dbffd010af7713156ccfeecd019a6e8eedefaf (patch)
treea705aa97941bf4c6907a6dd1b8e34d7d65ed6060
parentc7590cd9f3ca6242dd05e2a35b16c256a8759087 (diff)
downloadcoreboot-19dbffd010af7713156ccfeecd019a6e8eedefaf.tar.xz
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 <subrata.banik@intel.com> Reviewed-on: https://review.coreboot.org/21536 Tested-by: build bot (Jenkins) <no-reply@coreboot.org> Reviewed-by: Aaron Durbin <adurbin@chromium.org> Reviewed-by: Sumeet R Pawnikar <sumeet.r.pawnikar@intel.com>
-rw-r--r--src/arch/x86/ebda.c59
-rw-r--r--src/arch/x86/include/arch/ebda.h20
2 files changed, 78 insertions, 1 deletions
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 <arch/ebda.h>
#include <arch/acpi.h>
#include <commonlib/endian.h>
+#include <console/console.h>
+
+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