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authorNikita Kiryanov <nikita@compulab.co.il>2013-02-24 21:28:43 +0000
committerTom Rini <trini@ti.com>2013-03-11 11:06:09 -0400
commitc08804853361bb7c6e2f9e0cdcdc0b327f71fe35 (patch)
treec534705bdd53f50cdf361b5715b93aaa46a055ed
parent48ec52910047e048a5857fdaf00679b85a952ec5 (diff)
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lcd: implement a callback for splashimage
On some architectures certain values of splashimage will lead to a data abort exception. Document the problem, and implement a callback for splashimage to reject such values. Cc: Anatolij Gustschin <agust@denx.de> Cc: Wolfgang Denk <wd@denx.de> Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il> Acked-by: Igor Grinberg <grinberg@compulab.co.il>
-rw-r--r--README11
-rw-r--r--common/lcd.c26
-rw-r--r--doc/README.displaying-bmps27
-rw-r--r--include/env_callback.h7
4 files changed, 71 insertions, 0 deletions
diff --git a/README b/README
index b8ed1f1..398d70d 100644
--- a/README
+++ b/README
@@ -1530,6 +1530,17 @@ CBFS (Coreboot Filesystem) support
allows for a "silent" boot where a splash screen is
loaded very quickly after power-on.
+ CONFIG_SPLASHIMAGE_GUARD
+
+ If this option is set, then U-Boot will prevent the environment
+ variable "splashimage" from being set to a problematic address
+ (see README.displaying-bmps and README.arm-unaligned-accesses).
+ This option is useful for targets where, due to alignment
+ restrictions, an improperly aligned BMP image will cause a data
+ abort. If you think you will not have problems with unaligned
+ accesses (for example because your toolchain prevents them)
+ there is no need to set this option.
+
CONFIG_SPLASH_SCREEN_ALIGN
If this option is set the splash image can be freely positioned
diff --git a/common/lcd.c b/common/lcd.c
index ba6975b..590bbb9 100644
--- a/common/lcd.c
+++ b/common/lcd.c
@@ -33,6 +33,8 @@
#include <common.h>
#include <command.h>
#include <stdarg.h>
+#include <search.h>
+#include <env_callback.h>
#include <linux/types.h>
#include <stdio_dev.h>
#if defined(CONFIG_POST)
@@ -1099,6 +1101,30 @@ static void *lcd_logo(void)
#endif /* CONFIG_LCD_LOGO && !CONFIG_LCD_INFO_BELOW_LOGO */
}
+#ifdef CONFIG_SPLASHIMAGE_GUARD
+static int on_splashimage(const char *name, const char *value, enum env_op op,
+ int flags)
+{
+ ulong addr;
+ int aligned;
+
+ if (op == env_op_delete)
+ return 0;
+
+ addr = simple_strtoul(value, NULL, 16);
+ /* See README.displaying-bmps */
+ aligned = (addr % 4 == 2);
+ if (!aligned) {
+ printf("Invalid splashimage value. Value must be 16 bit aligned, but not 32 bit aligned\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+U_BOOT_ENV_CALLBACK(splashimage, on_splashimage);
+#endif
+
void lcd_position_cursor(unsigned col, unsigned row)
{
console_col = min(col, CONSOLE_COLS - 1);
diff --git a/doc/README.displaying-bmps b/doc/README.displaying-bmps
new file mode 100644
index 0000000..3311541
--- /dev/null
+++ b/doc/README.displaying-bmps
@@ -0,0 +1,27 @@
+If you are experiencing hangups/data-aborts when trying to display a BMP image,
+the following might be relevant to your situation...
+
+Some architectures cannot handle unaligned memory accesses, and an attempt to
+perform one will lead to a data abort. On such architectures it is necessary to
+make sure all data is properly aligned, and in many situations simply choosing
+a 32 bit aligned address is enough to ensure proper alignment. This is not
+always the case when dealing with data that has an internal layout such as a
+BMP image:
+
+BMP images have a header that starts with 2 byte-size fields followed by mostly
+32 bit fields. The packed struct that represents this header can be seen below:
+
+typedef struct bmp_header {
+ /* Header */
+ char signature[2];
+ __u32 file_size;
+ __u32 reserved;
+ __u32 data_offset;
+ ... etc
+} __attribute__ ((packed)) bmp_header_t;
+
+When placed in an aligned address such as 0x80a00000, char signature offsets
+the __u32 fields into unaligned addresses (in our example 0x80a00002,
+0x80a00006, and so on...). When these fields are accessed by U-Boot, a 32 bit
+access is generated at a non-32-bit-aligned address, causing a data abort.
+The proper alignment for BMP images is therefore: 32-bit-aligned-address + 2.
diff --git a/include/env_callback.h b/include/env_callback.h
index c583120..62428d1 100644
--- a/include/env_callback.h
+++ b/include/env_callback.h
@@ -41,6 +41,12 @@
#define SILENT_CALLBACK
#endif
+#ifdef CONFIG_SPLASHIMAGE_GUARD
+#define SPLASHIMAGE_CALLBACK "splashimage:splashimage,"
+#else
+#define SPLASHIMAGE_CALLBACK
+#endif
+
/*
* This list of callback bindings is static, but may be overridden by defining
* a new association in the ".callbacks" environment variable.
@@ -51,6 +57,7 @@
"bootfile:bootfile," \
"loadaddr:loadaddr," \
SILENT_CALLBACK \
+ SPLASHIMAGE_CALLBACK \
"stdin:console,stdout:console,stderr:console," \
CONFIG_ENV_CALLBACK_LIST_STATIC