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 swarren@wwwdotorg.org --- v3: No change. v2: Updated to use macros etc. added in v2 of mbox driver patch. --- board/raspberrypi/rpi_b/rpi_b.c | 21 ++++++++++++++++++++- 1 file changed, 20 insertions(+), 1 deletion(-)
diff --git a/board/raspberrypi/rpi_b/rpi_b.c b/board/raspberrypi/rpi_b/rpi_b.c index 688b0aa..3c654a1 100644 --- a/board/raspberrypi/rpi_b/rpi_b.c +++ b/board/raspberrypi/rpi_b/rpi_b.c @@ -15,13 +15,32 @@ */
#include <common.h> +#include <asm/arch/mbox.h> #include <asm/global_data.h>
DECLARE_GLOBAL_DATA_PTR;
+struct msg_get_arm_mem { + struct bcm2835_mbox_hdr hdr; + struct bcm2835_mbox_tag_get_arm_mem get_arm_mem; + u32 end_tag; +}; + int dram_init(void) { - gd->ram_size = CONFIG_SYS_SDRAM_SIZE; + ALLOC_ALIGN_BUFFER(struct msg_get_arm_mem, msg, 1, 16); + int ret; + + BCM2835_MBOX_INIT_HDR(msg); + BCM2835_MBOX_INIT_TAG(&msg->get_arm_mem, GET_ARM_MEMORY); + + ret = bcm2835_mbox_call_prop(BCM2835_MBOX_PROP_CHAN, &msg->hdr); + if (ret) { + printf("bcm2835: Could not query ARM memory size\n"); + return -1; + } + + gd->ram_size = msg->get_arm_mem.body.resp.mem_size;
return 0; }