linux-kernel - Re: [PATCH 4/7] iommu: dart: Support a variable number of TTBRs per stream

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Message-Id: <6852ebfa-bebc-48cf-a31c-04801fc90af1@app.fastmail.com>
Date:   Wed, 04 Jan 2023 14:18:52 +0100
From:   "Sven Peter" <sven@...npeter.dev>
To:     "Hector Martin" <marcan@...can.st>,
        "Joerg Roedel" <joro@...tes.org>, "Will Deacon" <will@...nel.org>,
        "Robin Murphy" <robin.murphy@....com>
Cc:     "Alyssa Rosenzweig" <alyssa@...enzweig.io>,
        "Janne Grunau" <j@...nau.net>, "Rob Herring" <robh+dt@...nel.org>,
        "Krzysztof Kozlowski" <krzysztof.kozlowski+dt@...aro.org>,
        devicetree@...r.kernel.org, iommu@...ts.linux.dev,
        asahi@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] iommu: dart: Support a variable number of TTBRs per stream

On Wed, Jan 4, 2023, at 12:00, Hector Martin wrote:
> T8110 only has one TTBR per stream, so un-hardcode that.
>
> Signed-off-by: Hector Martin <marcan@...can.st>
> ---
>  drivers/iommu/apple-dart.c | 26 ++++++++++++++++++--------
>  1 file changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/iommu/apple-dart.c b/drivers/iommu/apple-dart.c
> index 48743bcd5b9d..189487c1d978 100644
> --- a/drivers/iommu/apple-dart.c
> +++ b/drivers/iommu/apple-dart.c
> @@ -77,15 +77,21 @@
>  #define DART_TCR_BYPASS0_ENABLE BIT(8)
>  #define DART_TCR_BYPASS1_ENABLE BIT(12)
> 
> -#define DART_TTBR(sid, idx) (0x200 + 16 * (sid) + 4 * (idx))
>  #define DART_TTBR_VALID BIT(31)
>  #define DART_TTBR_SHIFT 12
> 
> +#define DART_TTBR(dart, sid, idx) (0x200 + \
> +				   (((dart)->hw->ttbr_count * (sid)) << 2) + \
> +				   ((idx) << 2))
> +
> +
>  struct apple_dart_hw {
>  	u32 oas;
>  	enum io_pgtable_fmt fmt;
> 
>  	int max_sid_count;
> +
> +	int ttbr_count;
>  };
> 
>  /*
> @@ -245,7 +251,7 @@ static void apple_dart_hw_set_ttbr(struct 
> apple_dart_stream_map *stream_map,
>  	WARN_ON(paddr & ((1 << DART_TTBR_SHIFT) - 1));
>  	for_each_set_bit(sid, stream_map->sidmap, dart->num_streams)
>  		writel(DART_TTBR_VALID | (paddr >> DART_TTBR_SHIFT),
> -		       dart->regs + DART_TTBR(sid, idx));
> +		       dart->regs + DART_TTBR(dart, sid, idx));
>  }
> 
>  static void apple_dart_hw_clear_ttbr(struct apple_dart_stream_map 
> *stream_map,
> @@ -255,7 +261,7 @@ static void apple_dart_hw_clear_ttbr(struct 
> apple_dart_stream_map *stream_map,
>  	int sid;
> 
>  	for_each_set_bit(sid, stream_map->sidmap, dart->num_streams)
> -		writel(0, dart->regs + DART_TTBR(sid, idx));
> +		writel(0, dart->regs + DART_TTBR(dart, sid, idx));
>  }
> 
>  static void
> @@ -263,7 +269,7 @@ apple_dart_hw_clear_all_ttbrs(struct 
> apple_dart_stream_map *stream_map)
>  {
>  	int i;
> 
> -	for (i = 0; i < DART_MAX_TTBR; ++i)
> +	for (i = 0; i < stream_map->dart->hw->ttbr_count; ++i)
>  		apple_dart_hw_clear_ttbr(stream_map, i);
>  }
> 
> @@ -415,7 +421,7 @@ apple_dart_setup_translation(struct 
> apple_dart_domain *domain,
>  	for (i = 0; i < pgtbl_cfg->apple_dart_cfg.n_ttbrs; ++i)
>  		apple_dart_hw_set_ttbr(stream_map, i,
>  				       pgtbl_cfg->apple_dart_cfg.ttbr[i]);
> -	for (; i < DART_MAX_TTBR; ++i)
> +	for (; i < stream_map->dart->hw->ttbr_count; ++i)
>  		apple_dart_hw_clear_ttbr(stream_map, i);
> 
>  	apple_dart_hw_enable_translation(stream_map);
> @@ -956,11 +962,15 @@ static const struct apple_dart_hw apple_dart_hw_t8103 = {
>  	.oas = 36,
>  	.fmt = APPLE_DART,
>  	.max_sid_count = 16,
> +
> +	.ttbr_count = 4,
>  };
>  static const struct apple_dart_hw apple_dart_hw_t6000 = {
>  	.oas = 42,
>  	.fmt = APPLE_DART2,
>  	.max_sid_count = 16,
> +
> +	.ttbr_count = 4,
>  };
> 
>  static __maybe_unused int apple_dart_suspend(struct device *dev)
> @@ -970,9 +980,9 @@ static __maybe_unused int apple_dart_suspend(struct 
> device *dev)
> 
>  	for (sid = 0; sid < dart->num_streams; sid++) {
>  		dart->save_tcr[sid] = readl_relaxed(dart->regs + DART_TCR(sid));
> -		for (idx = 0; idx < DART_MAX_TTBR; idx++)
> +		for (idx = 0; idx < dart->hw->ttbr_count; idx++)
>  			dart->save_ttbr[sid][idx] =
> -				readl(dart->regs + DART_TTBR(sid, idx));
> +				readl(dart->regs + DART_TTBR(dart, sid, idx));
>  	}
> 
>  	return 0;
> @@ -993,7 +1003,7 @@ static __maybe_unused int apple_dart_resume(struct 
> device *dev)
>  	for (sid = 0; sid < dart->num_streams; sid++) {
>  		for (idx = 0; idx < DART_MAX_TTBR; idx++)

s/DART_MAX_TTBR/dart->hw->ttbr_count/ I think.

With that fixed:

Reviewed-by: Sven Peter <sven@...npeter.dev>



Sven