[PATCH 5/6] remoteproc: mtk_apu: Don't try to use the APU local RAM

[Alexandre Bailon]

Currently, this local RAM is not accessible from the CPU.
If the CPU tries to access it, then the CPU will hang.

Remoteproc may try to use it when it load a firmware
that has some sections in the local RAM.
This workarounds the issue by skiping this section.

Signed-off-by: Alexandre Bailon <abailon at baylibre.com>
---
 drivers/remoteproc/mtk_apu_rproc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/drivers/remoteproc/mtk_apu_rproc.c b/drivers/remoteproc/mtk_apu_rproc.c
index 565b3adca5de..e16d3258a785 100644
--- a/drivers/remoteproc/mtk_apu_rproc.c
+++ b/drivers/remoteproc/mtk_apu_rproc.c
@@ -57,6 +57,9 @@
 #define CORE_DEFAULT2_SPIDEN			BIT(0)
 #define CORE_XTENSA_ALTRESETVEC			(0x000001F8)
 
+#define DRAM0_START				(0x7ff00000)
+#define IRAM0_END				(0x7ff80000)
+
 struct mtk_vpu_rproc {
 	struct device *dev;
 	struct rproc *rproc;
@@ -139,6 +142,7 @@ static void mtk_vpu_rproc_kick(struct rproc *rproc, int vqid)
 
 int mtk_vpu_elf_sanity_check(struct rproc *rproc, const struct firmware *fw)
 {
+	struct mtk_vpu_rproc *vpu_rproc = rproc->priv;
 	const u8 *elf_data = fw->data;
 	struct elf32_hdr *ehdr;
 	struct elf32_phdr *phdr;
@@ -156,6 +160,16 @@ int mtk_vpu_elf_sanity_check(struct rproc *rproc, const struct firmware *fw)
 		/* Remove empty PT_LOAD section */
 		if (phdr->p_type == PT_LOAD && !phdr->p_paddr)
 			phdr->p_type = PT_NULL;
+		/*
+		 * Workaround: Currently, the CPU can't access to the APU
+		 * local RAM. This removes the local RAM section from the
+		 * firmware. Please note that may cause some issues.
+		 */
+		if (phdr->p_paddr >= DRAM0_START && phdr->p_paddr < IRAM0_END) {
+			dev_warn_once(vpu_rproc->dev,
+				      "Skipping the APU local RAM section\n");
+			phdr->p_type = PT_NULL;
+		}
 	}
 
 	return 0;
-- 
2.26.2