[PATCH RFC v9 2/6] dma: mpc512x: add support for peripheral transfers

[Andy Shevchenko]

On Wed, 2014-03-12 at 15:47 +0400, Alexander Popov wrote:
> Introduce support for slave s/g transfer preparation and the associated
> device control callback in the MPC512x DMA controller driver, which adds
> support for data transfers between memory and peripheral I/O to the
> previously supported mem-to-mem transfers.


> --- a/drivers/dma/mpc512x_dma.c
> +++ b/drivers/dma/mpc512x_dma.c
> @@ -2,6 +2,7 @@
>   * Copyright (C) Freescale Semicondutor, Inc. 2007, 2008.
>   * Copyright (C) Semihalf 2009
>   * Copyright (C) Ilya Yanok, Emcraft Systems 2010
> + * Copyright (C) Alexander Popov, Promcontroller 2013

2014?

[]

> +static int mpc_dma_device_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
> +							unsigned long arg)
> +{
> +	struct mpc_dma_chan *mchan;
> +	struct mpc_dma *mdma;
> +	struct dma_slave_config *cfg;
> +	unsigned long flags;
> +
> +	mchan = dma_chan_to_mpc_dma_chan(chan);
> +	switch (cmd) {
> +	case DMA_TERMINATE_ALL:
> +		/* Disable channel requests */
> +		mdma = dma_chan_to_mpc_dma(chan);
> +
> +		spin_lock_irqsave(&mchan->lock, flags);
> +
> +		out_8(&mdma->regs->dmacerq, chan->chan_id);
> +		list_splice_tail_init(&mchan->prepared, &mchan->free);
> +		list_splice_tail_init(&mchan->queued, &mchan->free);
> +		list_splice_tail_init(&mchan->active, &mchan->free);
> +
> +		spin_unlock_irqrestore(&mchan->lock, flags);
> +
> +		return 0;
> +	case DMA_SLAVE_CONFIG:
> +		/* Constraints:
> +		 *  - only transfers between a peripheral device and
> +		 *     memory are supported;
> +		 *  - minimal transfer chunk is 4 bytes and consequently
> +		 *     source and destination addresses must be 4-byte aligned
> +		 *     and transfer size must be aligned on (4 * maxburst)
> +		 *     boundary;
> +		 *  - during the transfer RAM address is being incremented by
> +		 *     the size of minimal transfer chunk;
> +		 *  - peripheral port's address is constant during the transfer.
> +		 */
> +
> +		cfg = (void *)arg;
> +
> +		if (!is_slave_direction(cfg->direction))
> +			return -EINVAL;

As far as I understand the intention you have not to use direction field
in the dma_slave_config. It will be removed once.

> +
> +		if (cfg->src_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES &&
> +			cfg->dst_addr_width != DMA_SLAVE_BUSWIDTH_4_BYTES)
> +			return -EINVAL;
> +
> +		spin_lock_irqsave(&mchan->lock, flags);
> +
> +		if (cfg->direction == DMA_DEV_TO_MEM) {
> +			mchan->per_paddr = cfg->src_addr;
> +			mchan->tcd_nunits = cfg->src_maxburst;
> +		} else {
> +			mchan->per_paddr = cfg->dst_addr;
> +			mchan->tcd_nunits = cfg->dst_maxburst;
> +		}

Ditto.


-- 
Andy Shevchenko <andriy.shevchenko at linux.intel.com>
Intel Finland Oy