From: Igor Opaniuk <igor.opan...@toradex.com>

i.MX 7's Cortex-M4 core can run from DDR and uses DDR memory for
the rpmsg communication. Both use cases need a fixed location of
memory reserved. For the rpmsg use case the reserved area needs
to be in sync with the kernel's hardcoded vring descriptor location.

Use the linux,usable-memory property to carve out 1MB of memory
in case the M4 core is running. Also make sure that the i.MX 7
specific rpmsg driver does not get loaded in case we do not carve
out memory.

Signed-off-by: Stefan Agner <stefan.ag...@toradex.com>
Signed-off-by: Igor Opaniuk <igor.opan...@toradex.com>
Reviewed-by: Oleksandr Suvorov <oleksandr.suvo...@toradex.com>
---

 arch/arm/include/asm/mach-imx/sys_proto.h |  2 ++
 board/toradex/colibri_imx7/colibri_imx7.c | 37 +++++++++++++++++++++++
 2 files changed, 39 insertions(+)

diff --git a/arch/arm/include/asm/mach-imx/sys_proto.h 
b/arch/arm/include/asm/mach-imx/sys_proto.h
index 52c83ba9e4..c9b509e6a7 100644
--- a/arch/arm/include/asm/mach-imx/sys_proto.h
+++ b/arch/arm/include/asm/mach-imx/sys_proto.h
@@ -153,6 +153,8 @@ void init_src(void);
 void init_snvs(void);
 void imx_wdog_disable_powerdown(void);
 
+int arch_auxiliary_core_check_up(u32 core_id);
+
 int board_mmc_get_env_dev(int devno);
 
 int nxp_board_rev(void);
diff --git a/board/toradex/colibri_imx7/colibri_imx7.c 
b/board/toradex/colibri_imx7/colibri_imx7.c
index c001316591..b0914a9ead 100644
--- a/board/toradex/colibri_imx7/colibri_imx7.c
+++ b/board/toradex/colibri_imx7/colibri_imx7.c
@@ -333,6 +333,43 @@ int checkboard(void)
 #if defined(CONFIG_OF_LIBFDT) && defined(CONFIG_OF_BOARD_SETUP)
 int ft_board_setup(void *blob, bd_t *bd)
 {
+#if defined(CONFIG_IMX_BOOTAUX) && defined(CONFIG_ARCH_FIXUP_FDT_MEMORY)
+       int up;
+
+       up = arch_auxiliary_core_check_up(0);
+       if (up) {
+               int ret;
+               int areas = 1;
+               u64 start[2], size[2];
+
+               /*
+                * Reserve 1MB of memory for M4 (1MiB is also the minimum
+                * alignment for Linux due to MMU section size restrictions).
+                */
+               start[0] = gd->bd->bi_dram[0].start;
+               size[0] = SZ_256M - SZ_1M;
+
+               /* If needed, create a second entry for memory beyond 256M */
+               if (gd->bd->bi_dram[0].size > SZ_256M) {
+                       start[1] = gd->bd->bi_dram[0].start + SZ_256M;
+                       size[1] = gd->bd->bi_dram[0].size - SZ_256M;
+                       areas = 2;
+               }
+
+               ret = fdt_set_usable_memory(blob, start, size, areas);
+               if (ret) {
+                       eprintf("Cannot set usable memory\n");
+                       return ret;
+               }
+       } else {
+               int off;
+
+               off = fdt_node_offset_by_compatible(blob, -1,
+                                                   "fsl,imx7d-rpmsg");
+               if (off > 0)
+                       fdt_status_disabled(blob, off);
+       }
+#endif
 #if defined(CONFIG_FDT_FIXUP_PARTITIONS)
        static const struct node_info nodes[] = {
                { "fsl,imx7d-gpmi-nand", MTD_DEV_TYPE_NAND, }, /* NAND flash */
-- 
2.17.1

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