Re: [PATCH 3/5] armv8: fsl-layerscape: create bypass smmu mapping for MC

[Robin Murphy <robin.murphy@arm.com>]

On 2023-09-06 17:01, Laurentiu Tudor wrote:
> MC being a plain DMA master as any other device in the SoC and
> being live at OS boot time, as soon as the SMMU is probed it
> will immediately start triggering faults because there is no
> mapping in the SMMU for the MC. Pre-create such a mapping in
> the SMMU, being the OS's responsibility to preserve it.

Does U-Boot enable the SMMU? AFAICS the only thing it knows how to do is 
explicitly turn it *off*, therefore programming other registers appears 
to be a complete waste of time.

All that should matter to the OS, and that it is responsible for 
upholding, is the reserved memory regions from patch #2. For instance, 
if the OS is Linux, literally the first thing arm_smmu_device_reset() 
does is rewrite all the S2CRs and SMRs without so much as looking.

Thanks,
Robin.

> Signed-off-by: Laurentiu Tudor <laurentiu.tudor@nxp.com>
> ---
>   arch/arm/cpu/armv8/fsl-layerscape/soc.c       | 26 ++++++++++++++++---
>   .../asm/arch-fsl-layerscape/immap_lsch3.h     |  9 +++++++
>   2 files changed, 32 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/cpu/armv8/fsl-layerscape/soc.c b/arch/arm/cpu/armv8/fsl-layerscape/soc.c
> index 3bfdc3f77431..870b99838ab5 100644
> --- a/arch/arm/cpu/armv8/fsl-layerscape/soc.c
> +++ b/arch/arm/cpu/armv8/fsl-layerscape/soc.c
> @@ -376,6 +376,18 @@ void bypass_smmu(void)
>   	val = (in_le32(SMMU_NSCR0) | SCR0_CLIENTPD_MASK) & ~(SCR0_USFCFG_MASK);
>   	out_le32(SMMU_NSCR0, val);
>   }
> +
> +void setup_smmu_mc_bypass(int icid, int mask)
> +{
> +	u32 val;
> +
> +	val = SMMU_SMR_VALID_MASK | (icid << SMMU_SMR_ID_SHIFT) |
> +		(mask << SMMU_SMR_MASK_SHIFT);
> +	out_le32(SMMU_REG_SMR(0), val);
> +	val = SMMU_S2CR_EXIDVALID_VALID_MASK | SMMU_S2CR_TYPE_BYPASS_MASK;
> +	out_le32(SMMU_REG_S2CR(0), val);
> +}
> +
>   void fsl_lsch3_early_init_f(void)
>   {
>   	erratum_rcw_src();
> @@ -402,10 +414,18 @@ void fsl_lsch3_early_init_f(void)
>   		bypass_smmu();
>   #endif
>   
> -#if defined(CONFIG_ARCH_LS1088A) || defined(CONFIG_ARCH_LS1028A) || \
> -	defined(CONFIG_ARCH_LS2080A) || defined(CONFIG_ARCH_LX2160A) || \
> -	defined(CONFIG_ARCH_LX2162A)
> +#ifdef CONFIG_ARCH_LS1028A
> +	set_icids();
> +#endif
> +
> +#if defined(CONFIG_ARCH_LS1088A) || defined(CONFIG_ARCH_LS2080A)
> +	set_icids();
> +	setup_smmu_mc_bypass(0x300, 0);
> +#endif
> +
> +#if defined(CONFIG_ARCH_LX2160A) || defined(CONFIG_ARCH_LX2162A)
>   	set_icids();
> +	setup_smmu_mc_bypass(0x4000, 0);
>   #endif
>   }
>   
> diff --git a/arch/arm/include/asm/arch-fsl-layerscape/immap_lsch3.h b/arch/arm/include/asm/arch-fsl-layerscape/immap_lsch3.h
> index ca5e33379ba9..bec5355adaed 100644
> --- a/arch/arm/include/asm/arch-fsl-layerscape/immap_lsch3.h
> +++ b/arch/arm/include/asm/arch-fsl-layerscape/immap_lsch3.h
> @@ -190,6 +190,15 @@
>   #define SCR0_CLIENTPD_MASK		0x00000001
>   #define SCR0_USFCFG_MASK		0x00000400
>   
> +#define SMMU_REG_SMR(n)			(SMMU_BASE + 0x800 + ((n) << 2))
> +#define SMMU_REG_S2CR(n)		(SMMU_BASE + 0xc00 + ((n) << 2))
> +#define SMMU_SMR_VALID_MASK		0x80000000
> +#define SMMU_SMR_MASK_MASK		0xffff0000
> +#define SMMU_SMR_MASK_SHIFT		16
> +#define SMMU_SMR_ID_MASK		0x0000ffff
> +#define SMMU_SMR_ID_SHIFT		0
> +#define SMMU_S2CR_EXIDVALID_VALID_MASK	0x00000400
> +#define SMMU_S2CR_TYPE_BYPASS_MASK	0x00010000
>   
>   /* PCIe */
>   #define CFG_SYS_PCIE1_ADDR			(CONFIG_SYS_IMMR + 0x2400000)