[PATCH v2 2/3] remoteproc: imx_rproc: Pass bootaddr to SM CPU/LMM reset vector

[Peng Fan (OSS)]

From: Peng Fan <peng.fan at nxp.com>

Cortex-M[7,33] processors use a fixed reset vector table format:

  0x00  Initial SP value
  0x04  Reset vector
  0x08  NMI
  0x0C  ...
  ...
  IRQ[n]

In ELF images, the corresponding layout is:

reset_vectors:  --> hardware reset address
        .word __stack_end__
        .word Reset_Handler
        .word NMI_Handler
        .word HardFault_Handler
        ...
        .word UART_IRQHandler
        .word SPI_IRQHandler
        ...

Reset_Handler:  --> ELF entry point address
        ...

The hardware fetches the first two words from reset_vectors and populates
SP with __stack_end__ and PC with Reset_Handler. Execution proceeds from
Reset_Handler.

However, the ELF entry point does not always match the hardware reset
address. For example, on i.MX94 CM33S:

  ELF entry point:     0x0ffc211d
  hardware reset base: 0x0ffc0000 (default reset value, sw programmable)

To derive the correct hardware reset address, the unused lower bits must
be masked off. The boot code should apply a SoC-specific mask before
programming the reset address registers, e.g.:

  reset_address = entry & reset_vector_mask

Current driver always programs the reset vector as 0. But i.MX94 CM33S's
default reset base is 0x0ffc0000, so the correct reset vector must be
passed to the SM API; otherwise the M33 Sync core cannot boot successfully.

rproc_elf_get_boot_addr() returns the ELF entry point, which is not the
hardware reset vector address. To derive the proper reset vector, this
patch introduces imx_rproc_get_boot_addr(), which masks the ELF entry
point using the SoC‑specific 'reset_vector_mask'. The resulting reset
vector address is then passed to the SM CPU/LMM reset vector API calls.

Signed-off-by: Peng Fan <peng.fan at nxp.com>
---
 drivers/remoteproc/imx_rproc.c | 17 ++++++++++++++---
 drivers/remoteproc/imx_rproc.h |  2 ++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
index 0dd80e688b0ea3df4c66e5726884dc86c8a5a881..d8ead42640881bd523d605fa7002935ef6e98077 100644
--- a/drivers/remoteproc/imx_rproc.c
+++ b/drivers/remoteproc/imx_rproc.c
@@ -345,7 +345,7 @@ static int imx_rproc_sm_cpu_start(struct rproc *rproc)
 	const struct imx_rproc_dcfg *dcfg = priv->dcfg;
 	int ret;
 
-	ret = scmi_imx_cpu_reset_vector_set(dcfg->cpuid, 0, true, false, false);
+	ret = scmi_imx_cpu_reset_vector_set(dcfg->cpuid, rproc->bootaddr, true, false, false);
 	if (ret) {
 		dev_err(priv->dev, "Failed to set reset vector cpuid(%u): %d\n", dcfg->cpuid, ret);
 		return ret;
@@ -365,7 +365,7 @@ static int imx_rproc_sm_lmm_start(struct rproc *rproc)
 	 * If the remoteproc core can't start the M7, it will already be
 	 * handled in imx_rproc_sm_lmm_prepare().
 	 */
-	ret = scmi_imx_lmm_reset_vector_set(dcfg->lmid, dcfg->cpuid, 0, 0);
+	ret = scmi_imx_lmm_reset_vector_set(dcfg->lmid, dcfg->cpuid, 0, rproc->bootaddr);
 	if (ret) {
 		dev_err(dev, "Failed to set reset vector lmid(%u), cpuid(%u): %d\n",
 			dcfg->lmid, dcfg->cpuid, ret);
@@ -739,6 +739,17 @@ imx_rproc_elf_find_loaded_rsc_table(struct rproc *rproc, const struct firmware *
 	return rproc_elf_find_loaded_rsc_table(rproc, fw);
 }
 
+static u64 imx_rproc_get_boot_addr(struct rproc *rproc, const struct firmware *fw)
+{
+	struct imx_rproc *priv = rproc->priv;
+	u32 reset_vector_mask = GENMASK_U32(31, 0);
+
+	if (priv->dcfg->reset_vector_mask)
+		reset_vector_mask = priv->dcfg->reset_vector_mask;
+
+	return rproc_elf_get_boot_addr(rproc, fw) & reset_vector_mask;
+}
+
 static const struct rproc_ops imx_rproc_ops = {
 	.prepare	= imx_rproc_prepare,
 	.attach		= imx_rproc_attach,
@@ -752,7 +763,7 @@ static const struct rproc_ops imx_rproc_ops = {
 	.find_loaded_rsc_table = imx_rproc_elf_find_loaded_rsc_table,
 	.get_loaded_rsc_table = imx_rproc_get_loaded_rsc_table,
 	.sanity_check	= rproc_elf_sanity_check,
-	.get_boot_addr	= rproc_elf_get_boot_addr,
+	.get_boot_addr	= imx_rproc_get_boot_addr,
 };
 
 static int imx_rproc_addr_init(struct imx_rproc *priv,
diff --git a/drivers/remoteproc/imx_rproc.h b/drivers/remoteproc/imx_rproc.h
index d37e6f90548cec727b4aeb874680b42af85bdbb4..0d7d48352a1091ad24e8e083172ce6da6d26ae10 100644
--- a/drivers/remoteproc/imx_rproc.h
+++ b/drivers/remoteproc/imx_rproc.h
@@ -41,6 +41,8 @@ struct imx_rproc_dcfg {
 	/* For System Manager(SM) based SoCs */
 	u32				cpuid; /* ID of the remote core */
 	u32				lmid;  /* ID of the Logcial Machine */
+	/* reset_vector = elf_entry_addr & reset_vector_mask */
+	u32				reset_vector_mask;
 };
 
 #endif /* _IMX_RPROC_H */

-- 
2.37.1