The firmware running on the bcm2835 SoC's VideoCore CPU determines how
much of the system RAM is available for use by the ARM CPU. Previously,
U-Boot assumed that only 128MB was available, since this was the
smallest value configured by any public firmware. However, we can now
query the actual value at run-time from the firmware using the mbox
property protocol.
Signed-off-by: Stephen Warren <swar...@wwwdotorg.org>
---
board/raspberrypi/rpi_b/rpi_b.c | 20 +++++++++++++++++++-
1 file changed, 19 insertions(+), 1 deletion(-)
diff --git a/board/raspberrypi/rpi_b/rpi_b.c b/board/raspberrypi/rpi_b/rpi_b.c
index 688b0aa..88f8c58 100644
--- a/board/raspberrypi/rpi_b/rpi_b.c
+++ b/board/raspberrypi/rpi_b/rpi_b.c
@@ -15,13 +15,31 @@
*/
#include <common.h>
+#include <asm/arch/mbox.h>
#include <asm/global_data.h>
DECLARE_GLOBAL_DATA_PTR;
int dram_init(void)
{
- gd->ram_size = CONFIG_SYS_SDRAM_SIZE;
+ ALLOC_ALIGN_BUFFER(struct bcm2835_mbox_buf_get_arm_mem, buf, 1, 16);
+
+ memset(buf, 0, sizeof(*buf));
+ buf->hdr.buf_size = sizeof(*buf);
+ buf->hdr.code = BCM2835_MBOX_REQ_CODE;
+ buf->tag_hdr.tag = BCM2835_MBOX_TAG_GET_ARM_MEMORY;
+ buf->tag_hdr.val_buf_size = sizeof(buf->body);
+ buf->tag_hdr.val_len = sizeof(buf->body.req);
+
+ bcm2835_mbox_call_prop(BCM2835_MBOX_PROP_CHAN, &buf->hdr);
+
+ if ((buf->hdr.code != BCM2835_MBOX_RESP_CODE_SUCCESS) ||
+ (!(buf->tag_hdr.val_len & BCM2835_MBOX_TAG_VAL_LEN_RESPONSE))) {
+ printf("BCM2835_MBOX_TAG_GET_ARM_MEMORY failed\n");
+ return -1;
+ }
+
+ gd->ram_size = buf->body.resp.mem_size;
return 0;
}
--
1.7.9.5
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