On Monday 15 September 2014, Ludovic Desroches wrote:
>
> +config AT_XDMAC
> + tristate "Atmel XDMA support"
> + depends on ARCH_AT91
> + select DMA_ENGINE
> + help
> + Support the Atmel XDMA controller.
This should depend on (ARCH_AT91 || COMPILE_TEST) and built on x86 to
get into the usual automated build checkers.
> +static struct dma_chan *at_xdmac_xlate(struct of_phandle_args *dma_spec,
> + struct of_dma *of_dma)
> +{
> + struct at_xdmac *atxdmac = of_dma->of_dma_data;
> + struct at_xdmac_chan *atchan;
> + struct dma_chan *chan;
> + struct device *dev = atxdmac->dma.dev;
> + dma_cap_mask_t mask;
> +
> + if (dma_spec->args_count != 2) {
> + dev_err(dev, "dma phandler args: bad number of args\n");
> + return NULL;
> + }
> +
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_SLAVE, mask);
The mask is unused, just remove it.
> + chan = dma_get_any_slave_channel(&atxdmac->dma);
> + if (!chan) {
> + dev_err(dev, "can't get a dma channel\n");
> + return NULL;
> + }
> +
> + atchan = to_at_xdmac_chan(chan);
> + atchan->memif = AT91_XDMAC_DT_GET_MEM_IF(dma_spec->args[0]);
> + atchan->perif = AT91_XDMAC_DT_GET_PER_IF(dma_spec->args[0]);
> + atchan->perid = AT91_XDMAC_DT_GET_PERID(dma_spec->args[1]);
> + dev_info(dev, "chan dt cfg: memif=%u perif=%u perid=%u\n",
> + atchan->memif, atchan->perif, atchan->perid);
Maybe dev_dbg instead of dev_info?
I think having three cells would be nicer here, so you can get rid of the
macros.
> diff --git a/drivers/dma/at_xdmac.h b/drivers/dma/at_xdmac.h
> new file mode 100644
> index 0000000..5f4d898
> --- /dev/null
> +++ b/drivers/dma/at_xdmac.h
The header is only used in one file, so just move the contents into that file.
> +
> +static inline void __iomem *at_xdmac_chan_reg_base(struct at_xdmac *atxdmac, unsigned int chan_nb)
> +{
> + return (void __iomem *)(atxdmac->regs + (AT_XDMAC_CHAN_REG_BASE + chan_nb * 0x40));
> +}
That type cast should not be needed. Is atxdmac->regs not already a void __iomem *
> +#define at_xdmac_read(atxdmac, reg) readl_relaxed((atxdmac)->regs + (reg))
> +#define at_xdmac_write(atxdmac, reg, value) \
> + writel_relaxed((value), (atxdmac)->regs + (reg))
> +
> +#define at_xdmac_chan_read(atchan, reg) readl_relaxed((atchan)->ch_regs + (reg))
> +#define at_xdmac_chan_write(atchan, reg, value) writel_relaxed((value), (atchan)->ch_regs + (reg))
Is writel_relaxed the right accessor here? I haven't reviewed all uses of this,
but you have to ensure that every use that needs synchronization against the
actual DMA has explicit barriers here.
(0x2 << AT91_DMA_CFG_FIFOCFG_OFFSET) /* single AHB access */
>
> +
> +/* ---------- XDMAC ---------- */
> +#define AT91_XDMAC_DT_MEM_IF_MASK (0x1)
> +#define AT91_XDMAC_DT_MEM_IF_OFFSET (16)
> +#define AT91_XDMAC_DT_MEM_IF(mem_if) (((mem_if) & AT91_XDMAC_DT_MEM_IF_MASK) \
> + << AT91_XDMAC_DT_MEM_IF_OFFSET)
> +#define AT91_XDMAC_DT_GET_MEM_IF(cfg) (((cfg) >> AT91_XDMAC_DT_MEM_IF_OFFSET) \
> + & AT91_XDMAC_DT_MEM_IF_MASK)
> +
> +#define AT91_XDMAC_DT_PER_IF_MASK (0x1)
> +#define AT91_XDMAC_DT_PER_IF_OFFSET (0)
> +#define AT91_XDMAC_DT_PER_IF(per_if) (((per_if) & AT91_XDMAC_DT_PER_IF_MASK) \
> + << AT91_XDMAC_DT_PER_IF_OFFSET)
> +#define AT91_XDMAC_DT_GET_PER_IF(cfg) (((cfg) >> AT91_XDMAC_DT_PER_IF_OFFSET) \
> + & AT91_XDMAC_DT_PER_IF_MASK)
> +
> +#define AT91_XDMAC_DT_PERID_MASK (0x7f)
> +#define AT91_XDMAC_DT_PERID_OFFSET (24)
> +#define AT91_XDMAC_DT_PERID(perid) (((perid) & AT91_XDMAC_DT_PERID_MASK) \
> + << AT91_XDMAC_DT_PERID_OFFSET)
> +#define AT91_XDMAC_DT_GET_PERID(cfg) (((cfg) >> AT91_XDMAC_DT_PERID_OFFSET) \
> + & AT91_XDMAC_DT_PERID_MASK)
As mentioned, I think it would be much better to keep the macros inside of the
driver and not visible to the binding, so you can use simple numbers in DT.
Arnd
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