[PATCH 24/32] dmaengine: ste_dma40: Supply full Device Tree parsing support

Mon Apr 22 06:16:06 EDT 2013

On Thu, Apr 18, 2013 at 11:12:06AM +0100, Lee Jones wrote:
> Using the new DMA DT bindings and API, we can register the DMA40 driver
> as Device Tree capable. Now, when a client attempts to allocate a
> channel using the DMA DT bindings via its own node, we are able to parse
> the request and allocate a channel in the correct manor.
typo						    ^^^^^
> 
> Cc: Vinod Koul <vinod.koul at intel.com>
> Cc: Dan Williams <djbw at fb.com>
> Cc: Per Forlin <per.forlin at stericsson.com>
> Cc: Rabin Vincent <rabin at rab.in>
> Signed-off-by: Lee Jones <lee.jones at linaro.org>
> ---
>  .../devicetree/bindings/dma/ste-dma40.txt          |   66 ++++++++++++++++++++
>  drivers/dma/ste_dma40.c                            |   58 +++++++++++++++++
>  2 files changed, 124 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/dma/ste-dma40.txt
> 
> diff --git a/Documentation/devicetree/bindings/dma/ste-dma40.txt b/Documentation/devicetree/bindings/dma/ste-dma40.txt
> new file mode 100644
> index 0000000..1eb7958
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/ste-dma40.txt
> @@ -0,0 +1,66 @@
> +* DMA40 DMA Controller
> +
> +Required properties:
> +- compatible: "stericsson,dma40"
> +- reg: Address range of the DMAC registers
> +- interrupt: Should contain the DMAC interrupt number
> +- dma-channels: Number of channels supported by hardware
> +- #dma-cells: must be <3>
> +
> +Optional properties:
> +- interrupt-parent: Should be the phandle for the interrupt controller
> +  that services interrupts for this device
> +
> +Example:
> +
> +	dma: dma-controller at 801C0000 {
> +		compatible = "stericsson,db8500-dma40", "stericsson,dma40";
> +		reg = <0x801C0000 0x1000>;
> +		reg-names = "base";
> +		interrupt-parent = <&intc>;
> +		interrupts = <0 25 0x4>;
> +
> +		#dma-cells = <2>;
> +		dma-channels = <0>; /* Zero means read from H/W. */
> +	};
> +
This needs to be Acked-By Arnd..
> +Clients
> +Required properties:
> +- dmas: Comma seperated list of dma channel requests
> +- dma-names: Names of the aforementioned requested channels
> +
> +Each dmas request consists of 4 cells:
> +  1. A phandle pointing to the DMA controller
> +  2. The DMA request line number (only when 'use fixed channel' is set)
> +  3. Device Type
> +  4. A 32bit mask specifying; mode, direction and endianess [NB: This list will grow]
> +        bits 1-2: Mode:
> +          00: Logical
> +          01: Physical
> +          10: Operation
> +          11: Undefined - will most likely return an error
> +        bits 3-4: Direction:
> +          00: Mem to Mem
> +          01: Mem to Dev
> +          10: Dev to Mem
> +          11: Dev to Dev
> +        bit 5: Endianess:
> +           0: Little endian
> +           1: Big endian
> +        bit 6: Use fixed channel:
> +           0: Use automatic channel selection
> +           1: Use DMA request line number
> +
> +Example:
> +
> +	uart at 80120000 {
> +		compatible = "arm,pl011", "arm,primecell";
> +		reg = <0x80120000 0x1000>;
> +		interrupts = <0 11 0x4>;
> +
> +		dmas = <&dma 0 13 0x8>, /* Logical - DevToMem */
> +		       <&dma 0 13 0x4>; /* Logical - MemToDev */
> +		dma-names = "rx", "rx";
> +
> +		status = "disabled";
> +	};
> diff --git a/drivers/dma/ste_dma40.c b/drivers/dma/ste_dma40.c
> index 4782ee7..9115c0e 100644
> --- a/drivers/dma/ste_dma40.c
> +++ b/drivers/dma/ste_dma40.c
> @@ -18,6 +18,7 @@
>  #include <linux/pm_runtime.h>
>  #include <linux/err.h>
>  #include <linux/of.h>
> +#include <linux/of_dma.h>
>  #include <linux/amba/bus.h>
>  #include <linux/regulator/consumer.h>
>  #include <linux/platform_data/dma-ste-dma40.h>
> @@ -2409,6 +2410,56 @@ static void d40_set_prio_realtime(struct d40_chan *d40c)
>  		__d40_set_prio_rt(d40c, d40c->dma_cfg.dev_type, false);
>  }
>  
> +#define D40_DT_FLAGS_MODE(flags)       ((flags >> 0) & 0x3)
> +#define D40_DT_FLAGS_DIR(flags)        ((flags >> 2) & 0x3)
> +#define D40_DT_FLAGS_BIG_ENDIAN(flags) ((flags >> 4) & 0x1)
> +#define D40_DT_FLAGS_FIXED_CHAN(flags) ((flags >> 5) & 0x1)
> +
> +static struct dma_chan *d40_xlate(struct of_phandle_args *dma_spec,
> +				  struct of_dma *ofdma)
> +{
> +	struct stedma40_chan_cfg cfg;
> +	dma_cap_mask_t cap;
> +	u32 flags;
> +
> +	memset(&cfg, 0, sizeof(struct stedma40_chan_cfg));
> +
> +	dma_cap_zero(cap);
> +	dma_cap_set(DMA_SLAVE, cap);
> +
> +	cfg.dev_type = dma_spec->args[1];
> +	flags = dma_spec->args[2];
> +
> +	switch (D40_DT_FLAGS_MODE(flags)) {
> +	case 0: cfg.mode = STEDMA40_MODE_LOGICAL; break;
> +	case 1: cfg.mode = STEDMA40_MODE_PHYSICAL; break;
> +	case 2: cfg.mode = STEDMA40_MODE_OPERATION; break;
> +	default:
> +		pr_err("dma40: Unknown mode read from DT (%d)\n",
> +		       D40_DT_FLAGS_MODE(flags));
> +		return NULL;
> +	}
> +
> +	switch (D40_DT_FLAGS_DIR(flags)) {
> +	case 0: cfg.dir = STEDMA40_MEM_TO_MEM; break;
> +	case 1: cfg.dir = STEDMA40_MEM_TO_PERIPH; break;
> +	case 2: cfg.dir = STEDMA40_PERIPH_TO_MEM; break;
> +	case 3: cfg.dir = STEDMA40_PERIPH_TO_PERIPH; break;
this looks ugly to me, Checkpatch should have complained..
Break could be on subsequent lines...
> +	}
> +
> +	if (cfg.dir == STEDMA40_PERIPH_TO_MEM)
> +		cfg.src_info.big_endian = D40_DT_FLAGS_BIG_ENDIAN(flags);
> +	if (cfg.dir == STEDMA40_MEM_TO_PERIPH)
> +		cfg.dst_info.big_endian = D40_DT_FLAGS_BIG_ENDIAN(flags);
> +
> +	if (D40_DT_FLAGS_FIXED_CHAN(flags)) {
> +		cfg.phy_channel = dma_spec->args[0];
> +		cfg.use_fixed_channel = true;
> +	}
> +
> +	return dma_request_channel(cap, stedma40_filter, &cfg);
> +}
> +
>  /* DMA ENGINE functions */
>  static int d40_alloc_chan_resources(struct dma_chan *chan)
>  {
> @@ -3615,6 +3666,13 @@ static int __init d40_probe(struct platform_device *pdev)
>  
>  	d40_hw_init(base);
>  
> +	if (np) {
> +		err = of_dma_controller_register(np, d40_xlate, NULL);
> +		if (err && err != -ENODEV)
> +			dev_err(&pdev->dev,
> +				"could not register of_dma_controller\n");
> +	}
> +
>  	dev_info(base->dev, "initialized\n");
>  	return 0;
>  
> -- 
> 1.7.10.4
>