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Message-ID: <20130802140951.GP2884@e106331-lin.cambridge.arm.com>
Date: Fri, 2 Aug 2013 15:09:51 +0100
From: Mark Rutland <mark.rutland@....com>
To: Jonas Jensen <jonas.jensen@...il.com>
Cc: "linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"linux@....linux.org.uk" <linux@....linux.org.uk>,
"arnd@...db.de" <arnd@...db.de>,
"vinod.koul@...el.com" <vinod.koul@...el.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"arm@...nel.org" <arm@...nel.org>, "djbw@...com" <djbw@...com>
Subject: Re: [PATCH v6] dmaengine: Add MOXA ART DMA engine driver
On Fri, Aug 02, 2013 at 02:28:45PM +0100, Jonas Jensen wrote:
> Add dmaengine driver for MOXA ART SoCs.
>
> Signed-off-by: Jonas Jensen <jonas.jensen@...il.com>
> ---
>
> Notes:
> Preemptively submitting a new version that has the previously
> mentioned two cell xlate.
>
> Changes since v5:
>
> 1. add line request number and use two cell xlate
>
> device tree bindings document:
> 2. update description, describe the two cells of #dma-cells
>
> Applies to next-20130802
>
> .../devicetree/bindings/dma/moxa,moxart-dma.txt | 21 +
> drivers/dma/Kconfig | 7 +
> drivers/dma/Makefile | 1 +
> drivers/dma/moxart-dma.c | 610 +++++++++++++++++++++
> 4 files changed, 639 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/dma/moxa,moxart-dma.txt
> create mode 100644 drivers/dma/moxart-dma.c
>
> diff --git a/Documentation/devicetree/bindings/dma/moxa,moxart-dma.txt b/Documentation/devicetree/bindings/dma/moxa,moxart-dma.txt
> new file mode 100644
> index 0000000..dc2b686
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/dma/moxa,moxart-dma.txt
> @@ -0,0 +1,21 @@
> +MOXA ART DMA Controller
> +
> +See dma.txt first
> +
> +Required properties:
> +
> +- compatible : Must be "moxa,moxart-dma"
> +- reg : Should contain registers location and length
> +- interrupts : Should contain the interrupt number
> +- #dma-cells : Should be 2
> + cell index 0: channel number between 0-3
> + cell index 1: line request number
> +
> +Example:
> +
> + dma: dma@...00000 {
> + compatible = "moxa,moxart-dma";
> + reg = <0x90500000 0x1000>;
> + interrupts = <24 0>;
> + #dma-cells = <1>;
This should be #dma-cells = <2>;
[...]
> +struct moxart_dma_reg {
> + u32 source_addr;
> + u32 dest_addr;
> +#define APB_DMA_CYCLES_MASK 0x00ffffff
> + u32 cycles; /* depend on burst mode */
> + u32 ctrl;
> +};
I'm not keen on relying on structs for register offsets, but at least
they're exact width u32s.
[...]
> +static int moxart_alloc_chan_resources(struct dma_chan *chan)
> +{
> + struct moxart_dma_chan *mchan = to_moxart_dma_chan(chan);
> + int i;
> + bool found = false;
> +
> + for (i = 0; i < APB_DMA_MAX_CHANNEL; i++) {
> + if (i == mchan->ch_num
> + && !mchan->allocated) {
> + dev_dbg(chan2dev(chan), "%s: allocating channel #%d\n",
> + __func__, mchan->ch_num);
> + mchan->allocated = true;
> + found = true;
Why not return 0 here...
> + break;
> + }
> + }
...and always return -ENODEV here?
That way you can also get rid of the found variable.
> +
> + if (!found)
> + return -ENODEV;
> +
> + return 0;
> +}
[...]
> +static struct irqaction moxart_dma_irq = {
> + .name = "moxart-dma-engine",
> + .flags = IRQF_DISABLED,
> + .handler = moxart_dma_interrupt,
> +};
> +
> +static int moxart_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct device_node *node = dev->of_node;
> + struct resource *res;
> + static void __iomem *dma_base_addr;
> + int ret, i;
> + unsigned int irq;
> + struct moxart_dma_chan *mchan;
> + struct moxart_dma_container *mdc;
> +
> + mdc = devm_kzalloc(dev, sizeof(*mdc), GFP_KERNEL);
> + if (!mdc) {
> + dev_err(dev, "can't allocate DMA container\n");
> + return -ENOMEM;
> + }
> +
> + irq = irq_of_parse_and_map(node, 0);
What if this fails (where irq == 0)?.
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + dma_base_addr = devm_ioremap_resource(dev, res);
> + if (IS_ERR(dma_base_addr)) {
> + dev_err(dev, "devm_ioremap_resource failed\n");
> + return PTR_ERR(dma_base_addr);
> + }
> +
> + mdc->ctlr = pdev->id;
> + spin_lock_init(&mdc->dma_lock);
> +
> + dma_cap_zero(mdc->dma_slave.cap_mask);
> + dma_cap_set(DMA_SLAVE, mdc->dma_slave.cap_mask);
> +
> + moxart_dma_init(&mdc->dma_slave, dev);
> +
> + mchan = &mdc->slave_chans[0];
> + for (i = 0; i < APB_DMA_MAX_CHANNEL; i++, mchan++) {
> + mchan->ch_num = i;
> + mchan->reg = (struct moxart_dma_reg *)(dma_base_addr + 0x80
> + + i * sizeof(struct moxart_dma_reg));
> + mchan->callback = NULL;
> + mchan->allocated = 0;
> + mchan->callback_param = NULL;
> +
> + dma_cookie_init(&mchan->chan);
> + mchan->chan.device = &mdc->dma_slave;
> + list_add_tail(&mchan->chan.device_node,
> + &mdc->dma_slave.channels);
> +
> + dev_dbg(dev, "%s: mchans[%d]: mchan->ch_num=%d mchan->reg=%p\n",
> + __func__, i, mchan->ch_num, mchan->reg);
> + }
> +
> + ret = dma_async_device_register(&mdc->dma_slave);
> + platform_set_drvdata(pdev, mdc);
> +
> + of_dma_controller_register(node, moxart_of_xlate, &moxart_dma_info);
> +
> + moxart_dma_irq.dev_id = &mdc->dma_slave;
> + setup_irq(irq, &moxart_dma_irq);
What if this fails?
Is there any reason you can't use request_irq over setup_irq?
> +
> + dev_dbg(dev, "%s: IRQ=%d\n", __func__, irq);
> +
> + return ret;
> +}
Thanks,
Mark.
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