[PATCH 3/3] remoteproc/mediatek: read IPI buffer offset from FW

[Tzung-Bi Shih]

Reads the IPI buffer offset from the FW binary.  The information resides
in addr of .ipi_buffer section.

Moves scp_ipi_init() to scp_load() phase.  The IPI buffer can be
initialized only if the offset is clear.

To backward compatible to MT8183 SCP, specify the offset in the board
specific mtk_scp_of_data.

Signed-off-by: Tzung-Bi Shih <tzungbi at google.com>
---
 drivers/remoteproc/mtk_scp.c | 73 ++++++++++++++++++++++++------------
 1 file changed, 49 insertions(+), 24 deletions(-)

diff --git a/drivers/remoteproc/mtk_scp.c b/drivers/remoteproc/mtk_scp.c
index 60ba4cece074..80ab5a30ea47 100644
--- a/drivers/remoteproc/mtk_scp.c
+++ b/drivers/remoteproc/mtk_scp.c
@@ -21,7 +21,7 @@
 #include "remoteproc_internal.h"
 
 #define MAX_CODE_SIZE 0x500000
-#define SCP_FW_END 0x7C000
+#define SECTION_NAME_IPI_BUFFER ".ipi_buffer"
 
 /**
  * scp_get() - get a reference to SCP.
@@ -119,16 +119,24 @@ static void scp_ipi_handler(struct mtk_scp *scp)
 	wake_up(&scp->ack_wq);
 }
 
-static int scp_ipi_init(struct mtk_scp *scp)
+static int scp_elf_read_ipi_buf_addr(struct mtk_scp *scp,
+				     const struct firmware *fw,
+				     size_t *offset);
+
+static int scp_ipi_init(struct mtk_scp *scp, const struct firmware *fw)
 {
-	size_t send_offset = SCP_FW_END - sizeof(struct mtk_share_obj);
-	size_t recv_offset = send_offset - sizeof(struct mtk_share_obj);
+	int ret;
+	size_t offset;
+
+	ret = scp_elf_read_ipi_buf_addr(scp, fw, &offset);
+	if (ret)
+		return ret;
+	dev_info(scp->dev, "IPI buf addr %#010zx\n", offset);
 
-	/* shared buffer initialization */
-	scp->recv_buf =
-		(struct mtk_share_obj __iomem *)(scp->sram_base + recv_offset);
-	scp->send_buf =
-		(struct mtk_share_obj __iomem *)(scp->sram_base + send_offset);
+	scp->recv_buf = (struct mtk_share_obj __iomem *)
+			(scp->sram_base + offset);
+	scp->send_buf = (struct mtk_share_obj __iomem *)
+			(scp->sram_base + offset + sizeof(*scp->recv_buf));
 	memset_io(scp->recv_buf, 0, sizeof(*scp->recv_buf));
 	memset_io(scp->send_buf, 0, sizeof(*scp->send_buf));
 
@@ -271,6 +279,32 @@ static int scp_elf_load_segments(struct rproc *rproc, const struct firmware *fw)
 	return ret;
 }
 
+static int scp_elf_read_ipi_buf_addr(struct mtk_scp *scp,
+				     const struct firmware *fw,
+				     size_t *offset)
+{
+	struct elf32_hdr *ehdr;
+	struct elf32_shdr *shdr, *shdr_strtab;
+	int i;
+	const u8 *elf_data = fw->data;
+	const char *strtab;
+
+	ehdr = (struct elf32_hdr *)elf_data;
+	shdr = (struct elf32_shdr *)(elf_data + ehdr->e_shoff);
+	shdr_strtab = shdr + ehdr->e_shstrndx;
+	strtab = (const char *)(elf_data + shdr_strtab->sh_offset);
+
+	for (i = 0; i < ehdr->e_shnum; i++, shdr++) {
+		if (strcmp(strtab + shdr->sh_name,
+			   SECTION_NAME_IPI_BUFFER) == 0) {
+			*offset = shdr->sh_addr;
+			return 0;
+		}
+	}
+
+	return -ENOENT;
+}
+
 static int mt8183_scp_before_load(struct mtk_scp *scp)
 {
 	/* Clear SCP to host interrupt */
@@ -350,11 +384,15 @@ static int scp_load(struct rproc *rproc, const struct firmware *fw)
 
 	ret = scp->data->scp_before_load(scp);
 	if (ret < 0)
-		return ret;
+		goto leave;
 
 	ret = scp_elf_load_segments(rproc, fw);
-	clk_disable_unprepare(scp->clk);
+	if (ret)
+		goto leave;
 
+	ret = scp_ipi_init(scp, fw);
+leave:
+	clk_disable_unprepare(scp->clk);
 	return ret;
 }
 
@@ -680,19 +718,6 @@ static int scp_probe(struct platform_device *pdev)
 		goto release_dev_mem;
 	}
 
-	ret = clk_prepare_enable(scp->clk);
-	if (ret) {
-		dev_err(dev, "failed to enable clocks\n");
-		goto release_dev_mem;
-	}
-
-	ret = scp_ipi_init(scp);
-	clk_disable_unprepare(scp->clk);
-	if (ret) {
-		dev_err(dev, "Failed to init ipi\n");
-		goto release_dev_mem;
-	}
-
 	/* register SCP initialization IPI */
 	ret = scp_ipi_register(scp, SCP_IPI_INIT, scp_init_ipi_handler, scp);
 	if (ret) {
-- 
2.29.2.299.gdc1121823c-goog