On Sat, Sep 13, 2014 at 09:53:00PM +0800, Chen-Yu Tsai wrote:
> The A23 SoC has the same dma engine as the A31 (sun6i), with a
> reduced amount of endpoints and physical channels. Add the proper
> config data and compatible string to support it.
>
> A slight difference in sun8i is an undocumented register needs
> to be toggled for dma to function.
>
> Signed-off-by: Chen-Yu Tsai <wens@xxxxxxxx>
> ---
> Documentation/devicetree/bindings/dma/sun6i-dma.txt | 2 +-
> drivers/dma/Kconfig | 4 ++--
> drivers/dma/sun6i-dma.c | 20 ++++++++++++++++++++
> 3 files changed, 23 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/dma/sun6i-dma.txt b/Documentation/devicetree/bindings/dma/sun6i-dma.txt
> index 3e145c1..9cdcba24d 100644
> --- a/Documentation/devicetree/bindings/dma/sun6i-dma.txt
> +++ b/Documentation/devicetree/bindings/dma/sun6i-dma.txt
> @@ -4,7 +4,7 @@ This driver follows the generic DMA bindings defined in dma.txt.
>
> Required properties:
>
> -- compatible: Must be "allwinner,sun6i-a31-dma"
> +- compatible: Must be "allwinner,sun6i-a31-dma" or "allwinner,sun8i-a23-dma"
> - reg: Should contain the registers base address and length
> - interrupts: Should contain a reference to the interrupt used by this device
> - clocks: Should contain a reference to the parent AHB clock
> diff --git a/drivers/dma/Kconfig b/drivers/dma/Kconfig
> index 9b1ea0e..5361aa7 100644
> --- a/drivers/dma/Kconfig
> +++ b/drivers/dma/Kconfig
> @@ -395,12 +395,12 @@ config XILINX_VDMA
>
> config DMA_SUN6I
> tristate "Allwinner A31 SoCs DMA support"
> - depends on MACH_SUN6I || COMPILE_TEST
> + depends on MACH_SUN6I || MACH_SUN8I || COMPILE_TEST
> depends on RESET_CONTROLLER
> select DMA_ENGINE
> select DMA_VIRTUAL_CHANNELS
> help
> - Support for the DMA engine for Allwinner A31 SoCs.
> + Support for the DMA engine first found in Allwinner A31 SoCs.
>
> config NBPFAXI_DMA
> tristate "Renesas Type-AXI NBPF DMA support"
> diff --git a/drivers/dma/sun6i-dma.c b/drivers/dma/sun6i-dma.c
> index 89ca0c4..29667dd 100644
> --- a/drivers/dma/sun6i-dma.c
> +++ b/drivers/dma/sun6i-dma.c
> @@ -878,8 +878,20 @@ static struct sun6i_dma_config sun6i_a31_dma_cfg = {
> .nr_max_vchans = 53,
> };
>
> +/*
> + * The A23 only has 8 physical channels, a maximum DRQ port id of 24,
> + * and a total of 37 usable source and destination endpoints.
> + */
> +
> +static struct sun6i_dma_config sun8i_a23_dma_cfg = {
> + .nr_max_channels = 8,
> + .nr_max_requests = 24,
> + .nr_max_vchans = 37,
> +};
> +
> static struct of_device_id sun6i_dma_match[] = {
> { .compatible = "allwinner,sun6i-a31-dma", .data = &sun6i_a31_dma_cfg },
> + { .compatible = "allwinner,sun8i-a23-dma", .data = &sun8i_a23_dma_cfg },
> { /* sentinel */ }
> };
>
> @@ -1008,6 +1020,14 @@ static int sun6i_dma_probe(struct platform_device *pdev)
> goto err_dma_unregister;
> }
>
> + /*
> + * sun8i variant requires us to toggle an undocumented register,
> + * as seen in Allwinner's SDK.
The BSP I have has this:
static void sunxi_dma_hw_init(struct sunxi_dmadev *dev)
{
struct sunxi_dmadev *sunxi_dev = dev;
clk_prepare_enable(sunxi_dev->ahb_clk);
#ifdef CONFIG_ARCH_SUN8IW3
writel(0x04, sunxi_dev->base + DMA_GATE);
#endif
}
/* All is ok, and open the clock */
sunxi_dma_hw_init(sunxi_dev);
So I guess we can say that it's not that undocumented :)
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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