remoteproc/mediatek: read IPI buffer offset from FW

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

Moves scp_ipi_init() to rproc_ops::parse_fw() 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.  Reads the default offset if the firmware
doesn't have it.
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20201202044609.2501913-1-tzungbi@google.comSigned-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

drivers/remoteproc/mtk_common.h

@@ -78,6 +78,8 @@ struct mtk_scp_of_data {
 
 	u32 host_to_scp_reg;
 	u32 host_to_scp_int_bit;
+
+	size_t ipi_buf_offset;
 };
 
 struct mtk_scp {

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 +119,29 @@ 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;
+
+	/* read the ipi buf addr from FW itself first */
+	ret = scp_elf_read_ipi_buf_addr(scp, fw, &offset);
+	if (ret) {
+		/* use default ipi buf addr if the FW doesn't have it */
+		offset = scp->data->ipi_buf_offset;
+		if (!offset)
+			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 +284,32 @@ 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 */
@@ -359,6 +398,23 @@ static int scp_load(struct rproc *rproc, const struct firmware *fw)
 	return ret;
 }
 
+static int scp_parse_fw(struct rproc *rproc, const struct firmware *fw)
+{
+	struct mtk_scp *scp = rproc->priv;
+	struct device *dev = scp->dev;
+	int ret;
+
+	ret = clk_prepare_enable(scp->clk);
+	if (ret) {
+		dev_err(dev, "failed to enable clocks\n");
+		return ret;
+	}
+
+	ret = scp_ipi_init(scp, fw);
+	clk_disable_unprepare(scp->clk);
+	return ret;
+}
+
 static int scp_start(struct rproc *rproc)
 {
 	struct mtk_scp *scp = (struct mtk_scp *)rproc->priv;
@@ -462,6 +518,7 @@ static const struct rproc_ops scp_ops = {
 	.stop		= scp_stop,
 	.load		= scp_load,
 	.da_to_va	= scp_da_to_va,
+	.parse_fw	= scp_parse_fw,
 };
 
 /**
@@ -681,19 +738,6 @@ 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) {
@@ -761,6 +805,7 @@ static const struct mtk_scp_of_data mt8183_of_data = {
 	.scp_stop = mt8183_scp_stop,
 	.host_to_scp_reg = MT8183_HOST_TO_SCP,
 	.host_to_scp_int_bit = MT8183_HOST_IPC_INT_BIT,
+	.ipi_buf_offset = 0x7bdb0,
 };
 
 static const struct mtk_scp_of_data mt8192_of_data = {