On 28.10.18 13:30, Baruch Siach wrote:
Some Armada 8K boards like Macchiatobin and Clearfog GT-8K use RAM from
external DIMM. Hard coding the RAM size in the device-tree is not
convenient. Fortunately, the ATF that initializes the RAM knows the size
of RAM, and U-Boot can query the ATF using a SMC call.

This code in this commit is mostly taken from downstream Marvell U-Boot
code by Grzegorz Jaszczyk.

CONFIG_NR_DRAM_BANKS must be set to 2 to use more than 3GB RAM.

Cc: Grzegorz Jaszczyk <j...@semihalf.com>
Signed-off-by: Baruch Siach <bar...@tkos.co.il>
---
  arch/arm/mach-mvebu/arm64-common.c | 47 +++++++++++++++++++++++++++++-
  1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/arch/arm/mach-mvebu/arm64-common.c 
b/arch/arm/mach-mvebu/arm64-common.c
index f47273fde9c6..7ba7301c7a8c 100644
--- a/arch/arm/mach-mvebu/arm64-common.c
+++ b/arch/arm/mach-mvebu/arm64-common.c
@@ -7,6 +7,7 @@
  #include <dm.h>
  #include <fdtdec.h>
  #include <linux/libfdt.h>
+#include <linux/sizes.h>
  #include <pci.h>
  #include <asm/io.h>
  #include <asm/system.h>
@@ -45,15 +46,59 @@ const struct mbus_dram_target_info 
*mvebu_mbus_dram_info(void)
/* DRAM init code ... */ +#define MV_SIP_DRAM_SIZE 0x82000010
+
+static u64 a8k_dram_scan_ap_sz(void)
+{
+       struct pt_regs pregs;
+
+       pregs.regs[0] = MV_SIP_DRAM_SIZE;
+       pregs.regs[1] = SOC_REGS_PHY_BASE;
+       smc_call(&pregs);
+
+       return pregs.regs[0];
+}
+
+static void a8k_dram_init_banksize(void)
+{
+       /*
+        * Config 2 DRAM banks:
+        * Bank 0 - max size 4G - 1G
+        * Bank 1 - ram size - 4G + 1G
+        */
+       phys_size_t max_bank0_size = SZ_4G - SZ_1G;
+
+       gd->bd->bi_dram[0].start = CONFIG_SYS_SDRAM_BASE;
+       if (gd->ram_size <= max_bank0_size) {
+               gd->bd->bi_dram[0].size = gd->ram_size;
+               return;
+       }
+
+       gd->bd->bi_dram[0].size = max_bank0_size;
+       if (CONFIG_NR_DRAM_BANKS > 1) {
+               gd->bd->bi_dram[1].start = SZ_4G;
+               gd->bd->bi_dram[1].size = gd->ram_size - max_bank0_size;
+       }

Is CONFIG_NR_DRAM_BANKS > 2 possible on one of these platforms?

Also I find the splitting of the available RAM size (detected via ATF)
onto the multiple banks not intuitive. Could you please explain the
1GiB hole in the bi_dram[x] struct? I suspect that this might have
something to do with the internal register address space. But I fail
to see, if this should be reflected in these bi_dram[x] values.

Thanks,
Stefan
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