Hi Vinod,
Thanks for a review.
On Wed, 7 May 2014, Vinod Koul wrote:
> On Sat, Apr 26, 2014 at 02:03:44PM +0200, Guennadi Liakhovetski wrote:
> > This patch adds a driver for NBPF DMAC IP cores from Renesas, designed for
> > the AMBA AXI bus.
> >
>
> > diff --git a/Documentation/devicetree/bindings/dma/nbpfaxi.txt b/Documentation/devicetree/bindings/dma/nbpfaxi.txt
> > new file mode 100644
> > index 0000000..d5e2522
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/dma/nbpfaxi.txt
> > @@ -0,0 +1,61 @@
> > +* Renesas "Type-AXI" NBPFAXI* DMA controllers
> > +
> > +* DMA controller
> > +
> > +Required properties
> > +
> > +- compatible: must be one of
> > + "renesas,nbpfaxi64dmac1b4"
> > + "renesas,nbpfaxi64dmac1b8"
> > + "renesas,nbpfaxi64dmac1b16"
> > + "renesas,nbpfaxi64dmac4b4"
> > + "renesas,nbpfaxi64dmac4b8"
> > + "renesas,nbpfaxi64dmac4b16"
> > + "renesas,nbpfaxi64dmac8b4"
> > + "renesas,nbpfaxi64dmac8b8"
> > + "renesas,nbpfaxi64dmac8b16"
> > +- #dma-cells: must be 2: the first integer is a terminal number, to which this
> > + slave is connected, the second one is flags. Flags is a bitmask
> > + with the following bits defined:
> > +
> > +#define NBPF_SLAVE_RQ_HIGH 1
> > +#define NBPF_SLAVE_RQ_LOW 2
> > +#define NBPF_SLAVE_RQ_LEVEL 4
> > +
> > +Optional properties:
> > +
> > +You can use dma-channels and dma-requests as described in dma.txt, although they
> > +won't be used, this information is derived from the compatibility string.
> > +
> > +Example:
> > +
> > + dma: dma-controller@48000000 {
> > + compatible = "renesas,nbpfaxi64dmac8b4";
> > + reg = <0x48000000 0x400>;
> > + interrupts = <0 12 0x4
> > + 0 13 0x4
> > + 0 14 0x4
> > + 0 15 0x4
> > + 0 16 0x4
> > + 0 17 0x4
> > + 0 18 0x4
> > + 0 19 0x4>;
> > + #dma-cells = <2>;
> > + dma-channels = <8>;
> > + dma-requests = <8>;
> > + };
> > +
> > +* DMA client
> > +
> > +Required properties:
> > +
> > +dmas and dma-names are required, as described in dma.txt.
> > +
> > +Example:
> > +
> > +#include <dt-bindings/dma/nbpfaxi.h>
> > +
> > +...
> > + dmas = <&dma 0 (NBPF_SLAVE_RQ_HIGH | NBPF_SLAVE_RQ_LEVEL)
> > + &dma 1 (NBPF_SLAVE_RQ_HIGH | NBPF_SLAVE_RQ_LEVEL)>;
> > + dma-names = "rx", "tx";
>
> Pls split the DT bindings to seprate patch. This part needs ack from DT folks
I thaught it would be preferable for both to go into the tree
simultaneously, i.e. as a single patch, they can review and ack this patch
too, but ok, can do, np.
> > +static size_t nbpf_xfer_size(struct nbpf_device *nbpf,
> > + enum dma_slave_buswidth width, u32 burst)
> > +{
> > + size_t size;
> > +
> > + if (!burst)
> > + burst = 1;
> > +
> > + switch (width) {
> > + case DMA_SLAVE_BUSWIDTH_8_BYTES:
> > + size = 8 * burst;
> > + break;
> > + case DMA_SLAVE_BUSWIDTH_4_BYTES:
> > + size = 4 * burst;
> > + break;
> > + case DMA_SLAVE_BUSWIDTH_2_BYTES:
> > + size = 2 * burst;
> why not
> size = width * burst;
> for all these three cases?
because width is an enum, that "accidentally" coincides with the
respective numerical value. I find this confusing - if it's an enum, you
shouldn't use it in calculations. If it's a numerical value, just use it
explicitly, but mixing both...
> > + break;
> > + default:
> > + pr_warn("%s(): invalid bus width %u\n", __func__, width);
> > + case DMA_SLAVE_BUSWIDTH_1_BYTE:
> > + size = burst;
> this would fit too in above :)
>
> > +static void nbpf_cookie_update(struct nbpf_channel *chan, dma_cookie_t cookie)
> > +{
> > + dma_cookie_t forgotten = cookie - NBPF_STATUS_KEEP;
> > +
> > + if (cookie < NBPF_STATUS_KEEP && !chan->cookie_forgotten)
> > + /* Not forgetting yet */
> > + return;
> > +
> > + if (forgotten < DMA_MIN_COOKIE)
> > + /* Wrapped */
> > + forgotten = (DMA_MAX_COOKIE & ~NBPF_STATUS_MASK) + cookie;
> > + chan->cookie_forgotten = forgotten;
> > +}
> why dont use core handler for this? Why do you need to track forgotten?
This has been discussed in
http://thread.gmane.org/gmane.linux.kernel/1573412, where I mentioned,
that only an extended cookie handling algorithm in respective drivers can
provide status of failed / aborted transfers. You also proposed a patch
"[PATCH] dmaengine: add error callback for reporting transaction errors"
but it has been "put on hold" too. The above is such an attempt of
extended status handling, caching several latest transactions' status and
using that cache to report back to the user. But if it's not desired, I
can remove it, np.
> > +
> > +static bool nbpf_cookie_in_cache(struct nbpf_channel *chan,
> > + dma_cookie_t cookie, struct dma_tx_state *state)
> > +{
> > + if (cookie > chan->cookie_forgotten)
> > + return true;
> > +
> > + /*
> > + * We still remember the cookie, if it has wrapped beyond INT_MAX:
> > + * (1) forgotten is almost INT_MAX
> > + * cookie_forgotten >> NBPF_STATUS_SHIFT == DMA_MAX_COOKIE >> NBPF_STATUS_SHIFT
> > + * and enquired is small
> > + * (2)
> > + * cookie & ~NBPF_STATUS_MASK == 0
> Again this logic is handled so driver shoudl worry about this
>
> > + */
> > +
> > + return chan->cookie_forgotten >> NBPF_STATUS_SHIFT ==
> > + DMA_MAX_COOKIE >> NBPF_STATUS_SHIFT &&
> > + !(cookie < ~NBPF_STATUS_MASK);
> > +}
> > +
>
> > +static enum dma_status nbpf_tx_status(struct dma_chan *dchan,
> > + dma_cookie_t cookie, struct dma_tx_state *state)
> > +{
> > + struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > + enum dma_status status = dma_cookie_status(dchan, cookie, state);
> > + dma_cookie_t running = chan->running ? chan->running->async_tx.cookie : -EINVAL;
> > +
> > + if (chan->paused)
> > + status = DMA_PAUSED;
> > +
> > + /* Note: we cannot return residues for old cookies */
> ??? If cookie is completed then reside is 0. So how is this comment valid?
For completed ones it's 0, sure.
> > + if (state && cookie == running) {
> > + state->residue = nbpf_bytes_left(chan);
> > + dev_dbg(dchan->device->dev, "%s(): residue %u\n", __func__,
> > + state->residue);
> > + }
> > +
> > + if (status == DMA_IN_PROGRESS || status == DMA_PAUSED)
> > + return status;
> no residue here?
I only report back residue of the currently active transfer, or do you
mean I should put the complete size as a residue for not yet started
transfers?
> > +
> > + if (nbpf_cookie_in_cache(chan, cookie, state))
> > + return nbpf_cookie_cached(chan, cookie, state);
> > +
> > + return status;
> > +}
> > +
>
> > +static int nbpf_control(struct dma_chan *dchan, enum dma_ctrl_cmd cmd,
> > + unsigned long arg)
> > +{
> > + struct nbpf_channel *chan = nbpf_to_chan(dchan);
> > + struct dma_slave_config *config;
> > +
> > + dev_dbg(dchan->device->dev, "Entry %s(%d)\n", __func__, cmd);
> > +
> > + switch (cmd) {
> > + case DMA_TERMINATE_ALL:
> > + dev_dbg(dchan->device->dev, "Terminating\n");
> > + nbpf_chan_halt(chan);
> > + nbpf_chan_idle(chan);
> > + break;
> > + case DMA_SLAVE_CONFIG:
> > + if (!arg)
> > + return -EINVAL;
> > + config = (struct dma_slave_config *)arg;
> > +
> > + /*
> > + * We could check config->slave_id to match chan->terminal here,
> > + * but with DT they would be coming from the same source, so
> > + * such a check would be superflous
> > + */
> > +
> > + switch (config->direction) {
> > + case DMA_MEM_TO_DEV:
> > + chan->slave_addr = config->dst_addr;
> > + chan->slave_width = nbpf_xfer_size(chan->nbpf,
> > + config->dst_addr_width, 1);
> > + chan->slave_burst = nbpf_xfer_size(chan->nbpf,
> > + config->dst_addr_width,
> > + config->dst_maxburst);
> > + break;
> > + case DMA_DEV_TO_MEM:
> > + chan->slave_addr = config->src_addr;
> > + chan->slave_width = nbpf_xfer_size(chan->nbpf,
> > + config->src_addr_width, 1);
> > + chan->slave_burst = nbpf_xfer_size(chan->nbpf,
> > + config->src_addr_width,
> > + config->src_maxburst);
> pls store all as direction makes no sense here and will be removed.
> Now based on descriptor direction you need to use one set of above.
Hm, I find it a pity, since we don't actually need both. In this and most
other drivers, I think, only one side can be a slave device, the other
side is always RAM. So, we only need to configure addresses and burst
sizes of the slave size?
> > + break;
> > + default:
> > + return -EINVAL;
> > + }
> > + break;
> > + case DMA_PAUSE:
> > + chan->paused = true;
> > + nbpf_pause(chan);
> > + break;
> > + case DMA_RESUME:
> > + /* Leave unimplemented until we get a use case. */
> why not remove?
Ok
> > + default:
> > + return -ENXIO;
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static struct dma_async_tx_descriptor *nbpf_prep_sg(struct nbpf_channel *chan,
> > + struct scatterlist *src_sg, struct scatterlist *dst_sg,
> > + size_t len, enum dma_transfer_direction direction,
> > + unsigned long flags)
> > +{
> > + struct nbpf_link_desc *ldesc;
> > + struct scatterlist *mem_sg;
> > + struct nbpf_desc *desc;
> > + bool inc_src, inc_dst;
> > + int i = 0;
> > +
> > + switch (direction) {
> > + case DMA_DEV_TO_MEM:
> > + mem_sg = dst_sg;
> > + inc_src = false;
> > + inc_dst = true;
> > + break;
> empty line here and similar instance pls
Is this specified in the CodingStyle document or does checkpatch.pl
complain about such cases?...
> > + case DMA_MEM_TO_DEV:
> > + mem_sg = src_sg;
> > + inc_src = true;
> > + inc_dst = false;
> > + break;
> > + default:
> > + case DMA_MEM_TO_MEM:
> > + mem_sg = src_sg;
> > + inc_src = true;
> > + inc_dst = true;
> > + }
> > +
> > + desc = nbpf_desc_get(chan, len);
> > + if (!desc)
> > + return NULL;
> > +
> > + desc->async_tx.flags = flags;
> > + desc->async_tx.cookie = -EBUSY;
> > + desc->user_wait = false;
> > +
>
> > +static int nbpf_probe(struct platform_device *pdev)
> > +{
> > + struct device *dev = &pdev->dev;
> > + const struct of_device_id *of_id = of_match_device(nbpf_match, dev);
> > + struct device_node *np = dev->of_node;
> > + struct nbpf_device *nbpf;
> > + struct dma_device *dma_dev;
> > + struct resource *iomem, *irq_res;
> > + const struct nbpf_config *cfg;
> > + int num_channels;
> > + int ret, irq, eirq, i;
> > + int irqbuf[9] /* maximum 8 channels + error IRQ */;
> > + unsigned int irqs = 0;
> > +
> > + BUILD_BUG_ON(sizeof(struct nbpf_desc_page) > PAGE_SIZE);
> > +
> > + /* DT only */
> > + if (!np || !of_id || !of_id->data)
> > + return -ENODEV;
> > +
> > + cfg = of_id->data;
> > + num_channels = cfg->num_channels;
> > +
> > + nbpf = devm_kzalloc(dev, sizeof(*nbpf) + num_channels *
> > + sizeof(nbpf->chan[0]), GFP_KERNEL);
> I think we have devm_kcalloc for these things?
Ah, ok, missed this, thanks, will update!
Regards
Guennadi
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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