Re: [PATCH V2 5/6] remoteproc: imx_rproc: set Cortex-M stack/pc to TCML

[Mathieu Poirier]

On Fri, Jan 27, 2023 at 05:22:45PM +0800, Peng Fan (OSS) wrote:
> From: Peng Fan <peng.fan@xxxxxxx>
> 
> The i.MX8M Cortex-M core not has ROM. It has a requirement is
> the stack, pc value should be set in address 0 and 4 from the view of
> itself. From Cortex-A core view, the region is at TCML start address.
> 
> The stack and pc value are the first two words stored in section
> ".interrupts" of the firmware, and the section is the first section in
> the firmware.
> 
> When the firmware is built to run in TCML, there is no issue, because
> when copying elf segments, the first two words are copied to TCML also.
> 
> However when the firmware is built ro run in DDR, the first two words
> are not copied to TCML start address.
> 
> This patch is to find the ".interrupts" section, read out the first
> two words and write to TCML start address at offset 0 and 4.
> 
> Signed-off-by: Peng Fan <peng.fan@xxxxxxx>
> ---
>  drivers/remoteproc/imx_rproc.c | 37 +++++++++++++++++++++++++++++++++-
>  1 file changed, 36 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/remoteproc/imx_rproc.c b/drivers/remoteproc/imx_rproc.c
> index 295e0e0e869a..f5ee0c9bb09d 100644
> --- a/drivers/remoteproc/imx_rproc.c
> +++ b/drivers/remoteproc/imx_rproc.c
> @@ -7,6 +7,7 @@
>  #include <linux/arm-smccc.h>
>  #include <linux/clk.h>
>  #include <linux/err.h>
> +#include <linux/firmware.h>
>  #include <linux/firmware/imx/sci.h>
>  #include <linux/interrupt.h>
>  #include <linux/kernel.h>
> @@ -23,6 +24,7 @@
>  #include <linux/workqueue.h>
>  
>  #include "imx_rproc.h"
> +#include "remoteproc_elf_helpers.h"
>  #include "remoteproc_internal.h"
>  
>  #define IMX7D_SRC_SCR			0x0C
> @@ -634,6 +636,39 @@ static struct resource_table *imx_rproc_get_loaded_rsc_table(struct rproc *rproc
>  	return (struct resource_table __force *)priv->rsc_table;
>  }
>  
> +static u64 imx_rproc_get_boot_addr(struct rproc *rproc, const struct firmware *fw)
> +{
> +	struct imx_rproc *priv = rproc->priv;
> +	const u8 *elf_data = (void *)fw->data;
> +	u8 class = fw_elf_get_class(fw);
> +	u64 bootaddr = rproc_elf_get_boot_addr(rproc, fw);
> +	const void *shdr;
> +	void __iomem *va;
> +	u64 sh_addr, offset;
> +
> +	if (priv->dcfg->devtype == IMX_RPROC_IMX8M) {
> +		/*
> +		 * i.MX8M Cortex-M requires [stack, pc] be put in address
> +		 * [0, 4], so the da address is 0, size is 8 words.
> +		 */
> +		va = (__force void __iomem *)rproc_da_to_va(rproc, 0, 8, NULL);
> +		shdr = rproc_elf_find_shdr(rproc, fw, ".interrupts");
> +		if (!shdr || !va)
> +			return bootaddr;
> +		sh_addr = elf_shdr_get_sh_addr(class, shdr);

This isn't used - why is it still there? 

> +		offset = elf_shdr_get_sh_offset(class, shdr);
> +
> +		/*
> +		 * Write stack, pc to TCML start address. The TCML region
> +		 * is marked with ATT_IOMEM, so use writel.
> +		 */
> +		writel(*(u32 *)(elf_data + offset), va);
> +		writel(*(u32 *)(elf_data + offset + 4), va + 4);

Here you are writing 2 words at address 0x0 and 2 words at address 0x4. Why are
you saying the size is 8 words in the comment above?

> +	}
> +
> +	return bootaddr;
> +}
> +
>  static const struct rproc_ops imx_rproc_ops = {
>  	.prepare	= imx_rproc_prepare,
>  	.attach		= imx_rproc_attach,
> @@ -647,7 +682,7 @@ static const struct rproc_ops imx_rproc_ops = {
>  	.find_loaded_rsc_table = 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,
> -- 
> 2.37.1
>