linux-kernel - Re: [PATCH 01/10] dmaengine: sun6i: Correct setting of clock autogating register for A83T/H3

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Date:   Mon, 4 Sep 2017 00:23:09 +0100
From:   André Przywara <andre.przywara@....com>
To:     Stefan Brüns <stefan.bruens@...h-aachen.de>,
        linux-sunxi@...glegroups.com
Cc:     devicetree@...r.kernel.org, dmaengine@...r.kernel.org,
        Vinod Koul <vinod.koul@...el.com>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>, Rob Herring <robh+dt@...nel.org>,
        Code Kipper <codekipper@...il.com>
Subject: Re: [PATCH 01/10] dmaengine: sun6i: Correct setting of clock
 autogating register for A83T/H3

On 03/09/17 23:40, Stefan Brüns wrote:
> The H83T uses a compatible string different from the A23, but requires

      A83T

> the same clock autogating register setting.
> 
> The H3 also requires setting the clock autogating register, but has
> the register at a different offset.
> 
> Some currently available SoCs not yet supported by the sun6i-dma driver
> will require new compatible strings. These SoCs either follow the A23
> register model (e.g. V3s) or the H3 register model (A64, R40), so a new
> variable is added to the config struct to group SoCs with common register
> models.

As mentioned in that other mail, using the actual properties as names
here instead of grouping them to rather arbitrary groups seems more
useful and future-proof to me and should be easier to read.
In this case this should simplify this patch:
sun8i_a23_dma_cfg = {
 	.nr_max_channels = 8,
 	.nr_max_requests = 24,
 	.nr_max_vchans   = 37,
+	.auto_clock_gate = 0x20,
...
-	if (of_device_is_compatible(pdev->dev.of_node,
-				    "allwinner,sun8i-a23-dma"))
-		writel(SUN8I_DMA_GATE_ENABLE, sdc->base + SUN8I_DMA_GATE);
+	if (sdc->cfg->auto_clock_gate)
+		writel(SUN8I_DMA_GATE_ENABLE,
+		       sdc->base + sdc->cfg->auto_clock_gate);

> Signed-off-by: Stefan Brüns <stefan.bruens@...h-aachen.de>
> ---
>  drivers/dma/sun6i-dma.c | 34 +++++++++++++++++++++++++++++++---
>  1 file changed, 31 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> index a2358780ab2c..1d9b3be30d22 100644
> --- a/drivers/dma/sun6i-dma.c
> +++ b/drivers/dma/sun6i-dma.c
> @@ -48,6 +48,9 @@
>  #define SUN8I_DMA_GATE		0x20
>  #define SUN8I_DMA_GATE_ENABLE	0x4
>  
> +#define SUNXI_H3_SECURITE_REG		0x20

typo?	   SUNXI_H3_SECURITY_REG ?

Cheers,
Andre.

> +#define SUNXI_H3_DMA_GATE		0x28
> +#define SUNXI_H3_DMA_GATE_ENABLE	0x4
>  /*
>   * Channels specific registers
>   */
> @@ -90,6 +93,21 @@
>  #define NORMAL_WAIT	8
>  #define DRQ_SDRAM	1
>  
> +/*
> + * DMA Controller generations
> + *
> + * Newer SoC generations changed or added some register definitions:
> + * - A23 added a clock gate register
> + * - H3 has a different offset for the clock gating register,
> + *   the burst length field has a different offset in the channel
> + *   configuration register, also additional burst lengths/widths.
> + */
> +enum dmac_variant {
> +	DMAC_VARIANT_A31,
> +	DMAC_VARIANT_A23,
> +	DMAC_VARIANT_H3,
> +};
> +
>  /*
>   * Hardware channels / ports representation
>   *
> @@ -101,6 +119,7 @@ struct sun6i_dma_config {
>  	u32 nr_max_channels;
>  	u32 nr_max_requests;
>  	u32 nr_max_vchans;
> +	enum dmac_variant dmac_variant;
>  };
>  
>  /*
> @@ -998,6 +1017,7 @@ static struct sun6i_dma_config sun6i_a31_dma_cfg = {
>  	.nr_max_channels = 16,
>  	.nr_max_requests = 30,
>  	.nr_max_vchans   = 53,
> +	.dmac_variant    = DMAC_VARIANT_A31,
>  };
>  
>  /*
> @@ -1009,23 +1029,29 @@ static struct sun6i_dma_config sun8i_a23_dma_cfg = {
>  	.nr_max_channels = 8,
>  	.nr_max_requests = 24,
>  	.nr_max_vchans   = 37,
> +	.dmac_variant    = DMAC_VARIANT_A23,
>  };
>  
>  static struct sun6i_dma_config sun8i_a83t_dma_cfg = {
>  	.nr_max_channels = 8,
>  	.nr_max_requests = 28,
>  	.nr_max_vchans   = 39,
> +	.dmac_variant    = DMAC_VARIANT_A23,
>  };
>  
>  /*
>   * The H3 has 12 physical channels, a maximum DRQ port id of 27,
>   * and a total of 34 usable source and destination endpoints.
> + * It also supports additional burst lengths and bus widths,
> + * and the burst length fields have different offsets.
>   */
>  
>  static struct sun6i_dma_config sun8i_h3_dma_cfg = {
>  	.nr_max_channels = 12,
>  	.nr_max_requests = 27,
>  	.nr_max_vchans   = 34,
> +	.dmac_variant    = DMAC_VARIANT_H3,
> +};
>  };
>  
>  static const struct of_device_id sun6i_dma_match[] = {
> @@ -1177,11 +1203,13 @@ static int sun6i_dma_probe(struct platform_device *pdev)
>  	/*
>  	 * sun8i variant requires us to toggle a dma gating register,
>  	 * as seen in Allwinner's SDK. This register is not documented
> -	 * in the A23 user manual.
> +	 * in the A23 user manual, but appears in e.g. the H83T manual.
> +	 * For the H3, H5 and A64, the register has a different location
>  	 */
> -	if (of_device_is_compatible(pdev->dev.of_node,
> -				    "allwinner,sun8i-a23-dma"))
> +	if (sdc->cfg->dmac_variant == DMAC_VARIANT_A23)
>  		writel(SUN8I_DMA_GATE_ENABLE, sdc->base + SUN8I_DMA_GATE);
> +	else if (sdc->cfg->dmac_variant == DMAC_VARIANT_H3)
> +		writel(SUNXI_H3_DMA_GATE_ENABLE, sdc->base + SUNXI_H3_DMA_GATE);
>  
>  	return 0;
>  
>