Re: [PATCH 08/18] dmaengine: bcm2835: pass dma_chan to generic functions

[Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>]

Hi Frank.

On Wed, 5 Jun 2024 at 19:05, Frank Li <Frank.li@xxxxxxx> wrote:
>
> On Fri, May 24, 2024 at 07:26:52PM +0100, Dave Stevenson wrote:
> > From: Stefan Wahren <stefan.wahren@xxxxxxxx>
> >
> > In preparation to support more platforms pass the dma_chan to the
> > generic functions. This provides access to the DMA device and possible
> > platform specific data.
>
> why need this change? you can easy convert between dma_chan and
> bcm2835_chan.

These patches are leading to adding a bcm2711_chan structure for a new
(but very closely related) variant of the DMA controller.

dma_chan is the generic structure, therefore we can keep more
commonality between the variants if we use that wherever possible.

  Dave

> >
> > Signed-off-by: Stefan Wahren <wahrenst@xxxxxxx>
> > Signed-off-by: Dave Stevenson <dave.stevenson@xxxxxxxxxxxxxxx>
> > ---
> >  drivers/dma/bcm2835-dma.c | 24 ++++++++++++++----------
> >  1 file changed, 14 insertions(+), 10 deletions(-)
> >
> > diff --git a/drivers/dma/bcm2835-dma.c b/drivers/dma/bcm2835-dma.c
> > index e2f9c8692e6b..aefaa1f01d7f 100644
> > --- a/drivers/dma/bcm2835-dma.c
> > +++ b/drivers/dma/bcm2835-dma.c
> > @@ -288,12 +288,13 @@ static void bcm2835_dma_desc_free(struct virt_dma_desc *vd)
> >  }
> >
> >  static bool
> > -bcm2835_dma_create_cb_set_length(struct bcm2835_chan *chan,
> > +bcm2835_dma_create_cb_set_length(struct dma_chan *chan,
> >                                struct bcm2835_dma_cb *control_block,
> >                                size_t len, size_t period_len,
> >                                size_t *total_len)
> >  {
> > -     size_t max_len = bcm2835_dma_max_frame_length(chan);
> > +     struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> > +     size_t max_len = bcm2835_dma_max_frame_length(c);
> >
> >       /* set the length taking lite-channel limitations into account */
> >       control_block->length = min_t(u32, len, max_len);
> > @@ -417,7 +418,7 @@ static struct bcm2835_desc *bcm2835_dma_create_cb_chain(
> >               /* set up length in control_block if requested */
> >               if (buf_len) {
> >                       /* calculate length honoring period_length */
> > -                     if (bcm2835_dma_create_cb_set_length(c, control_block,
> > +                     if (bcm2835_dma_create_cb_set_length(chan, control_block,
> >                                                            len, period_len,
> >                                                            &total_len)) {
> >                               /* add extrainfo bits in info */
> > @@ -485,8 +486,9 @@ static void bcm2835_dma_fill_cb_chain_with_sg(
> >       }
> >  }
> >
> > -static void bcm2835_dma_abort(struct bcm2835_chan *c)
> > +static void bcm2835_dma_abort(struct dma_chan *chan)
> >  {
> > +     struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> >       void __iomem *chan_base = c->chan_base;
> >       long int timeout = 10000;
> >
> > @@ -513,8 +515,9 @@ static void bcm2835_dma_abort(struct bcm2835_chan *c)
> >       writel(BCM2835_DMA_RESET, chan_base + BCM2835_DMA_CS);
> >  }
> >
> > -static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
> > +static void bcm2835_dma_start_desc(struct dma_chan *chan)
> >  {
> > +     struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> >       struct virt_dma_desc *vd = vchan_next_desc(&c->vc);
> >       struct bcm2835_desc *d;
> >
> > @@ -533,7 +536,8 @@ static void bcm2835_dma_start_desc(struct bcm2835_chan *c)
> >
> >  static irqreturn_t bcm2835_dma_callback(int irq, void *data)
> >  {
> > -     struct bcm2835_chan *c = data;
> > +     struct dma_chan *chan = data;
> > +     struct bcm2835_chan *c = to_bcm2835_dma_chan(chan);
> >       struct bcm2835_desc *d;
> >       unsigned long flags;
> >
> > @@ -566,7 +570,7 @@ static irqreturn_t bcm2835_dma_callback(int irq, void *data)
> >                       vchan_cyclic_callback(&d->vd);
> >               } else if (!readl(c->chan_base + BCM2835_DMA_ADDR)) {
> >                       vchan_cookie_complete(&c->desc->vd);
> > -                     bcm2835_dma_start_desc(c);
> > +                     bcm2835_dma_start_desc(chan);
> >               }
> >       }
> >
> > @@ -594,7 +598,7 @@ static int bcm2835_dma_alloc_chan_resources(struct dma_chan *chan)
> >       }
> >
> >       return request_irq(c->irq_number, bcm2835_dma_callback,
> > -                        c->irq_flags, "DMA IRQ", c);
> > +                        c->irq_flags, "DMA IRQ", chan);
> >  }
> >
> >  static void bcm2835_dma_free_chan_resources(struct dma_chan *chan)
> > @@ -682,7 +686,7 @@ static void bcm2835_dma_issue_pending(struct dma_chan *chan)
> >
> >       spin_lock_irqsave(&c->vc.lock, flags);
> >       if (vchan_issue_pending(&c->vc) && !c->desc)
> > -             bcm2835_dma_start_desc(c);
> > +             bcm2835_dma_start_desc(chan);
> >
> >       spin_unlock_irqrestore(&c->vc.lock, flags);
> >  }
> > @@ -846,7 +850,7 @@ static int bcm2835_dma_terminate_all(struct dma_chan *chan)
> >       if (c->desc) {
> >               vchan_terminate_vdesc(&c->desc->vd);
> >               c->desc = NULL;
> > -             bcm2835_dma_abort(c);
> > +             bcm2835_dma_abort(chan);
> >       }
> >
> >       vchan_get_all_descriptors(&c->vc, &head);
> > --
> > 2.34.1
> >