On Mon, 2014-02-24 at 15:09 +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.
>
Few comments below.
> Signed-off-by: Alexander Popov <a13xp0p0v88@xxxxxxxxx>
> ---
> drivers/dma/mpc512x_dma.c | 235 +++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 230 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/dma/mpc512x_dma.c b/drivers/dma/mpc512x_dma.c
> index 2ce248b..8f504cb 100644
> --- 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
> *
> * Written by Piotr Ziecik <kosmo@xxxxxxxxxxxx>. Hardware description
> * (defines, structures and comments) was taken from MPC5121 DMA driver
> @@ -29,8 +30,17 @@
> */
>
> /*
> - * This is initial version of MPC5121 DMA driver. Only memory to memory
> - * transfers are supported (tested using dmatest module).
> + * MPC512x and MPC8308 DMA driver. It supports
> + * memory to memory data transfers (tested using dmatest module) and
> + * data transfers between memory and peripheral I/O memory
> + * by means of slave s/g with these limitations:
> + * - chunked transfers (transfers with more than one part) are refused
> + * as long as proper support for scatter/gather is missing;
> + * - transfers on MPC8308 always start from software as this SoC appears
> + * not to have external request lines for peripheral flow control;
> + * - minimal memory <-> I/O memory 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;
> */
>
> #include <linux/module.h>
> @@ -189,6 +199,7 @@ struct mpc_dma_desc {
> dma_addr_t tcd_paddr;
> int error;
> struct list_head node;
> + int will_access_peripheral;
> };
>
> struct mpc_dma_chan {
> @@ -201,6 +212,10 @@ struct mpc_dma_chan {
> struct mpc_dma_tcd *tcd;
> dma_addr_t tcd_paddr;
>
> + /* Settings for access to peripheral FIFO */
> + dma_addr_t per_paddr; /* FIFO address */
> + u32 tcd_nunits;
> +
> /* Lock for this structure */
> spinlock_t lock;
> };
> @@ -251,8 +266,23 @@ static void mpc_dma_execute(struct mpc_dma_chan *mchan)
> struct mpc_dma_desc *mdesc;
> int cid = mchan->chan.chan_id;
>
> - /* Move all queued descriptors to active list */
> - list_splice_tail_init(&mchan->queued, &mchan->active);
> + while (!list_empty(&mchan->queued)) {
> + mdesc = list_first_entry(&mchan->queued,
> + struct mpc_dma_desc, node);
> + /*
> + * Grab either several mem-to-mem transfer descriptors
> + * or one peripheral transfer descriptor,
> + * don't mix mem-to-mem and peripheral transfer descriptors
> + * within the same 'active' list.
> + */
> + if (mdesc->will_access_peripheral) {
> + if (list_empty(&mchan->active))
> + list_move_tail(&mdesc->node, &mchan->active);
> + break;
> + } else {
> + list_move_tail(&mdesc->node, &mchan->active);
> + }
> + }
>
> /* Chain descriptors into one transaction */
> list_for_each_entry(mdesc, &mchan->active, node) {
> @@ -278,7 +308,17 @@ static void mpc_dma_execute(struct mpc_dma_chan *mchan)
>
> if (first != prev)
> mdma->tcd[cid].e_sg = 1;
> - out_8(&mdma->regs->dmassrt, cid);
> +
> + if (mdma->is_mpc8308) {
> + /* MPC8308, no request lines, software initiated start */
> + out_8(&mdma->regs->dmassrt, cid);
> + } else if (first->will_access_peripheral) {
> + /* peripherals involved, start by external request signal */
Probably you have to keep style of all comments in the code. For
example, let's start sentences from a capital letter.
> + out_8(&mdma->regs->dmaserq, cid);
> + } else {
> + /* memory to memory transfer, software initiated start */
> + out_8(&mdma->regs->dmassrt, cid);
> + }
> }
>
> /* Handle interrupt on one half of DMA controller (32 channels) */
> @@ -596,6 +636,7 @@ mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src,
> }
>
> mdesc->error = 0;
> + mdesc->will_access_peripheral = 0;
> tcd = mdesc->tcd;
>
> /* Prepare Transfer Control Descriptor for this transaction */
> @@ -643,6 +684,187 @@ mpc_dma_prep_memcpy(struct dma_chan *chan, dma_addr_t dst, dma_addr_t src,
> return &mdesc->desc;
> }
>
> +static struct dma_async_tx_descriptor *
> +mpc_dma_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> + unsigned int sg_len, enum dma_transfer_direction direction,
> + unsigned long flags, void *context)
> +{
> + struct mpc_dma *mdma = dma_chan_to_mpc_dma(chan);
> + struct mpc_dma_chan *mchan = dma_chan_to_mpc_dma_chan(chan);
> + struct mpc_dma_desc *mdesc = NULL;
> + dma_addr_t per_paddr;
> + u32 tcd_nunits;
> + struct mpc_dma_tcd *tcd;
> + unsigned long iflags;
> + struct scatterlist *sg;
> + size_t len;
> + int iter, i;
> +
> + /* currently there is no proper support for scatter/gather */
> + if (sg_len != 1)
> + return NULL;
You may check direction right there using is_slave_direction().
> +
> + for_each_sg(sgl, sg, sg_len, i) {
> + spin_lock_irqsave(&mchan->lock, iflags);
> +
> + mdesc = list_first_entry(&mchan->free,
> + struct mpc_dma_desc, node);
> + if (!mdesc) {
> + spin_unlock_irqrestore(&mchan->lock, iflags);
> + /* try to free completed descriptors */
> + mpc_dma_process_completed(mdma);
> + return NULL;
> + }
> +
> + list_del(&mdesc->node);
> +
> + per_paddr = mchan->per_paddr;
> + tcd_nunits = mchan->tcd_nunits;
> +
> + spin_unlock_irqrestore(&mchan->lock, iflags);
> +
> + if (per_paddr == 0 || tcd_nunits == 0)
> + goto err_prep;
> +
> + mdesc->error = 0;
> + mdesc->will_access_peripheral = 1;
> + tcd = mdesc->tcd;
> +
> + /* Prepare Transfer Control Descriptor for this transaction */
> +
Maybe instead of empty line you can move tcd assignment here.
> + memset(tcd, 0, sizeof(struct mpc_dma_tcd));
> +
> + if (!IS_ALIGNED(sg_dma_address(sg), 4))
> + goto err_prep;
> +
> + if (direction == DMA_DEV_TO_MEM) {
> + tcd->saddr = per_paddr;
> + tcd->daddr = sg_dma_address(sg);
> + tcd->soff = 0;
> + tcd->doff = 4;
> + } else if (direction == DMA_MEM_TO_DEV) {
> + tcd->saddr = sg_dma_address(sg);
> + tcd->daddr = per_paddr;
> + tcd->soff = 4;
> + tcd->doff = 0;
> + } else
> + goto err_prep;
First, keep style of conditionals, second, you may remove this branch
and previous if in case of checking direction outside of loop.
> +
> + tcd->ssize = MPC_DMA_TSIZE_4;
> + tcd->dsize = MPC_DMA_TSIZE_4;
> +
> + len = sg_dma_len(sg);
> + tcd->nbytes = tcd_nunits * 4;
> + if (!IS_ALIGNED(len, tcd->nbytes))
> + goto err_prep;
> +
> + iter = len / tcd->nbytes;
> + if (iter >= 1 << 15) {
> + /* len is too big */
> + goto err_prep;
> + } else {
Redundant else branch.
> + /* citer_linkch contains the high bits of iter */
> + tcd->biter = iter & 0x1ff;
> + tcd->biter_linkch = iter >> 9;
> + tcd->citer = tcd->biter;
> + tcd->citer_linkch = tcd->biter_linkch;
> + }
> +
> + tcd->e_sg = 0;
> + tcd->d_req = 1;
> +
> + /* Place descriptor in prepared list */
> + spin_lock_irqsave(&mchan->lock, iflags);
> + list_add_tail(&mdesc->node, &mchan->prepared);
> + spin_unlock_irqrestore(&mchan->lock, iflags);
> + }
> +
> + return &mdesc->desc;
> +
> +err_prep:
> + /* Put the descriptor back */
> + spin_lock_irqsave(&mchan->lock, iflags);
> + list_add_tail(&mdesc->node, &mchan->free);
> + spin_unlock_irqrestore(&mchan->lock, iflags);
> +
> + return NULL;
> +}
> +
> +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 (cfg->direction != DMA_DEV_TO_MEM &&
> + cfg->direction != DMA_MEM_TO_DEV)
> + return -EINVAL;
is_slave_direction()
> +
> + 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;
> + }
> +
> + if (!IS_ALIGNED(mchan->per_paddr, 4)) {
> + spin_unlock_irqrestore(&mchan->lock, flags);
> + return -EINVAL;
> + }
> +
> + if (mchan->tcd_nunits == 0)
> + mchan->tcd_nunits = 1; /* apply default */
> +
> + spin_unlock_irqrestore(&mchan->lock, flags);
> +
> + return 0;
> + default:
> + return -ENOSYS;
Use break here.
> + }
> +
> + return -EINVAL;
> +}
> +
> static int mpc_dma_probe(struct platform_device *op)
> {
> struct device_node *dn = op->dev.of_node;
> @@ -727,9 +949,12 @@ static int mpc_dma_probe(struct platform_device *op)
> dma->device_issue_pending = mpc_dma_issue_pending;
> dma->device_tx_status = mpc_dma_tx_status;
> dma->device_prep_dma_memcpy = mpc_dma_prep_memcpy;
> + dma->device_prep_slave_sg = mpc_dma_prep_slave_sg;
> + dma->device_control = mpc_dma_device_control;
>
> INIT_LIST_HEAD(&dma->channels);
> dma_cap_set(DMA_MEMCPY, dma->cap_mask);
> + dma_cap_set(DMA_SLAVE, dma->cap_mask);
>
> for (i = 0; i < dma->chancnt; i++) {
> mchan = &mdma->channels[i];
--
Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Intel Finland Oy
--
To unsubscribe from this list: send the line "unsubscribe dmaengine" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
