linux-kernel - Re: [PATCH v2 5/7] iommu/exynos: Check if SysMMU v7 has VM registers

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Message-ID: <00191759-df90-c020-92e8-37454edba6e1@samsung.com>
Date:   Tue, 12 Jul 2022 17:47:46 +0200
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Sam Protsenko <semen.protsenko@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
Cc:     Joerg Roedel <joro@...tes.org>, Will Deacon <will@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Janghyuck Kim <janghyuck.kim@...sung.com>,
        Cho KyongHo <pullip.cho@...sung.com>,
        Daniel Mentz <danielmentz@...gle.com>,
        David Virag <virag.david003@...il.com>,
        Sumit Semwal <sumit.semwal@...aro.org>, iommu@...ts.linux.dev,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 5/7] iommu/exynos: Check if SysMMU v7 has VM
 registers


On 11.07.2022 01:06, Sam Protsenko wrote:
> SysMMU v7 can have Virtual Machine registers, which implement multiple
> translation domains. The driver should know if it's true or not, as VM
> registers shouldn't be accessed if not present. Read corresponding
> capabilities register to obtain that info, and store it in driver data.
>
> Signed-off-by: Sam Protsenko <semen.protsenko@...aro.org>

I would merge this with the next one. Imho this change doesn't make much 
sense on it's own.

> ---
> Changes in v2:
>    - Removed the 'const' qualifier for local non-pointer variables
>
>   drivers/iommu/exynos-iommu.c | 26 ++++++++++++++++++++++++++
>   1 file changed, 26 insertions(+)
>
> diff --git a/drivers/iommu/exynos-iommu.c b/drivers/iommu/exynos-iommu.c
> index 0cb1ce10db51..48681189ccf8 100644
> --- a/drivers/iommu/exynos-iommu.c
> +++ b/drivers/iommu/exynos-iommu.c
> @@ -135,6 +135,9 @@ static u32 lv2ent_offset(sysmmu_iova_t iova)
>   #define CFG_SYSSEL	(1 << 22) /* System MMU 3.2 only */
>   #define CFG_FLPDCACHE	(1 << 20) /* System MMU 3.2+ only */
>   
> +#define CAPA0_CAPA1_EXIST		BIT(11)
> +#define CAPA1_VCR_ENABLED		BIT(14)
> +
>   /* common registers */
>   #define REG_MMU_VERSION		0x034
>   
> @@ -154,6 +157,10 @@ static u32 lv2ent_offset(sysmmu_iova_t iova)
>   #define REG_V5_FAULT_AR_VA	0x070
>   #define REG_V5_FAULT_AW_VA	0x080
>   
> +/* v7.x registers */
> +#define REG_V7_CAPA0		0x870
> +#define REG_V7_CAPA1		0x874
> +
>   #define has_sysmmu(dev)		(dev_iommu_priv_get(dev) != NULL)
>   
>   enum {
> @@ -298,6 +305,9 @@ struct sysmmu_drvdata {
>   
>   	struct iommu_device iommu;	/* IOMMU core handle */
>   	const unsigned int *regs;	/* register set */
> +
> +	/* v7 fields */
> +	bool has_vcr;			/* virtual machine control register */
>   };
>   
>   static struct exynos_iommu_domain *to_exynos_domain(struct iommu_domain *dom)
> @@ -411,11 +421,27 @@ static void __sysmmu_get_version(struct sysmmu_drvdata *data)
>   		MMU_MAJ_VER(data->version), MMU_MIN_VER(data->version));
>   }
>   
> +static bool __sysmmu_has_capa1(struct sysmmu_drvdata *data)
> +{
> +	u32 capa0 = readl(data->sfrbase + REG_V7_CAPA0);
> +
> +	return capa0 & CAPA0_CAPA1_EXIST;
> +}
> +
> +static void __sysmmu_get_vcr(struct sysmmu_drvdata *data)
> +{
> +	u32 capa1 = readl(data->sfrbase + REG_V7_CAPA1);
> +
> +	data->has_vcr = capa1 & CAPA1_VCR_ENABLED;
> +}
> +
>   static void sysmmu_get_hw_info(struct sysmmu_drvdata *data)
>   {
>   	__sysmmu_enable_clocks(data);
>   
>   	__sysmmu_get_version(data);
> +	if (MMU_MAJ_VER(data->version) >= 7 && __sysmmu_has_capa1(data))
> +		__sysmmu_get_vcr(data);
>   	if (MMU_MAJ_VER(data->version) < 5)
>   		data->regs = sysmmu_regs[REG_SET_V1];
>   	else

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland