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Message-ID: <20130422101606.GR24632@intel.com>
Date: Mon, 22 Apr 2013 15:46:06 +0530
From: Vinod Koul <vinod.koul@...el.com>
To: Lee Jones <lee.jones@...aro.org>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
arnd@...db.de, linus.walleij@...ricsson.com,
Dan Williams <djbw@...com>,
Per Forlin <per.forlin@...ricsson.com>,
Rabin Vincent <rabin@....in>
Subject: Re: [PATCH 24/32] dmaengine: ste_dma40: Supply full Device Tree
parsing support
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@...el.com>
> Cc: Dan Williams <djbw@...com>
> Cc: Per Forlin <per.forlin@...ricsson.com>
> Cc: Rabin Vincent <rabin@....in>
> Signed-off-by: Lee Jones <lee.jones@...aro.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@...C0000 {
> + 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@...20000 {
> + 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
>
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