This is the only patch in the series, non-trivially touching Documentation/devicetree/bindings, let's cc it to devicetree mailing lists.
Thanks Guennadi On Tue, 23 Jul 2013, Guennadi Liakhovetski wrote: > Currently shdma DT nodes have to be placed under a multiplexer node. DMA > slave DT nodes then use that multiplexer's phandle in their "dmas" > properties. However, sometimes it can be necessary to let DMA slaves only > use a specific DMAC instance. In this case it would be logical to just use > the respective phandle in that slave's "dmas" property. For this to work > the referenced DMAC has to register a struct of_dma instance, which isn't > presently done. Instead the driver currently only registers one struct > of_dma for the multiplexer. This patch adds support for such > configurations. To enable this option a "#dma-cells" property also must be > added to the respective DMAC DT node. > > Signed-off-by: Guennadi Liakhovetski <[email protected]> > --- > > As mentioned in the cover letter patch, this is an RFC. We are certain, > that we want to be able to reference specific DMACs within multiplexers. > However, with the current implementation this cannot work, because single > DMAC DT nodes don't have of_dma objects associated with them, currently > there is only one such object per multiplexer. The proposal is to > implement such direct referencing by adding a "#dma-cells" property to > respective DT nodes, in which case an of_dma object will be allocated for > them too. > > Documentation/devicetree/bindings/dma/shdma.txt | 16 ++++++ > drivers/dma/sh/shdma.h | 7 +++ > drivers/dma/sh/shdmac.c | 66 > +++++++++++++++++++++++ > 3 files changed, 89 insertions(+), 0 deletions(-) > > diff --git a/Documentation/devicetree/bindings/dma/shdma.txt > b/Documentation/devicetree/bindings/dma/shdma.txt > index 6b015d6..aeed9b8 100644 > --- a/Documentation/devicetree/bindings/dma/shdma.txt > +++ b/Documentation/devicetree/bindings/dma/shdma.txt > @@ -27,6 +27,22 @@ Required properties: > "renesas,shdma-r8a7740" for the DMACs (not RTDMAC) on r8a7740 > "renesas,shdma-sh73a0" for the DMACs on sh73a0 > > +Optional properties: > +- #dma-cells: this property is only needed in one specific case: if > DMA slaves > + have to be able to request channels specifically from this DMAC, > + not from anyone from the multiplexer. In such a case the board > + .dts file can contain code, similar to this: > + > +&dma1 { > + #dma-cells = <1>; > +}; > + > +&mmc0 { > + dmas = <&dma1 0xd1 > + &dma1 0xd2>; > + dma-names = "tx", "rx"; > +}; > + > Example: > dmac: dma-mux0 { > compatible = "renesas,shdma-mux"; > diff --git a/drivers/dma/sh/shdma.h b/drivers/dma/sh/shdma.h > index 8394424..991316f 100644 > --- a/drivers/dma/sh/shdma.h > +++ b/drivers/dma/sh/shdma.h > @@ -23,6 +23,7 @@ > #define SH_DMAE_TCR_MAX 0x00FFFFFF /* 16MB */ > > struct device; > +struct device_node; > > struct sh_dmae_chan { > struct shdma_chan shdma_chan; > @@ -33,6 +34,11 @@ struct sh_dmae_chan { > int pm_error; > }; > > +struct sh_dmae_filter_info { > + u32 hw_req; > + struct device_node *of_node; > +}; > + > struct sh_dmae_device { > struct shdma_dev shdma_dev; > struct sh_dmae_chan *chan[SH_DMAE_MAX_CHANNELS]; > @@ -42,6 +48,7 @@ struct sh_dmae_device { > void __iomem *dmars; > unsigned int chcr_offset; > u32 chcr_ie_bit; > + struct sh_dmae_filter_info filter_info; > }; > > struct sh_dmae_regs { > diff --git a/drivers/dma/sh/shdmac.c b/drivers/dma/sh/shdmac.c > index 9ee3c28..fcaed8d 100644 > --- a/drivers/dma/sh/shdmac.c > +++ b/drivers/dma/sh/shdmac.c > @@ -22,6 +22,7 @@ > #include <linux/module.h> > #include <linux/of.h> > #include <linux/of_device.h> > +#include <linux/of_dma.h> > #include <linux/slab.h> > #include <linux/interrupt.h> > #include <linux/dmaengine.h> > @@ -665,6 +666,63 @@ static const struct shdma_ops sh_dmae_shdma_ops = { > .get_partial = sh_dmae_get_partial, > }; > > +static bool sh_dmae_chan_filter(struct dma_chan *chan, void *arg) > +{ > + struct sh_dmae_filter_info *info = arg; > + struct shdma_chan *schan = to_shdma_chan(chan); > + int match = info->hw_req; > + > + if (match < 0) > + /* No slave requested - arbitrary channel */ > + return true; > + > + dev_dbg(schan->dev, "%s(): trying %s for 0x%x\n", __func__, > + info->of_node->full_name, match); > + > + if (schan->dev->of_node != info->of_node) > + return false; > + > + return !sh_dmae_set_slave(schan, match, true); > +} > + > +static struct dma_chan *sh_dmae_of_xlate(struct of_phandle_args *dma_spec, > + struct of_dma *ofdma) > +{ > + struct sh_dmae_filter_info *info = ofdma->of_dma_data; > + u32 id = dma_spec->args[0]; > + dma_cap_mask_t mask; > + struct dma_chan *chan; > + > + if (dma_spec->args_count != 1) > + return NULL; > + > + dma_cap_zero(mask); > + /* Only slave DMA channels can be allocated via DT */ > + dma_cap_set(DMA_SLAVE, mask); > + > + info->hw_req = id; > + info->of_node = dma_spec->np; > + > + chan = dma_request_channel(mask, sh_dmae_chan_filter, info); > + if (chan) > + to_shdma_chan(chan)->hw_req = id; > + > + return chan; > +} > + > +static int sh_dmae_of_add(struct device *dev, struct sh_dmae_device *shdev) > +{ > + u32 cells; > + int ret = of_property_read_u32(dev->of_node, "#dma-cells", &cells); > + > + dev_dbg(dev, "%s(): %u (%d)\n", __func__, cells, ret); > + if (ret < 0 || !cells) > + return 0; > + > + return of_dma_controller_register(dev->of_node, > + sh_dmae_of_xlate, > &shdev->filter_info); > +} > + > static const struct of_device_id sh_dmae_of_match[] = { > {.compatible = "renesas,shdma-r8a73a4", .data = r8a73a4_shdma_devid,}, > {.compatible = "renesas,shdma-r8a7740", .data = r8a7740_shdma_devid,}, > @@ -845,6 +903,10 @@ static int sh_dmae_probe(struct platform_device *pdev) > } while (irq_cnt < pdata->channel_num && chanirq_res); > } > > + err = sh_dmae_of_add(&pdev->dev, shdev); > + if (err < 0) > + goto of_add_err; > + > /* Create DMA Channel */ > for (i = 0; i < irq_cnt; i++) { > err = sh_dmae_chan_probe(shdev, i, chan_irq[i], chan_flag[i]); > @@ -869,6 +931,8 @@ edmadevreg: > pm_runtime_get(&pdev->dev); > > chan_probe_err: > + of_dma_controller_free(pdev->dev.of_node); > +of_add_err: > sh_dmae_chan_remove(shdev); > > #if defined(CONFIG_CPU_SH4) || defined(CONFIG_ARCH_SHMOBILE) > @@ -895,6 +959,8 @@ static int sh_dmae_remove(struct platform_device *pdev) > struct sh_dmae_device *shdev = platform_get_drvdata(pdev); > struct dma_device *dma_dev = &shdev->shdma_dev.dma_dev; > > + of_dma_controller_free(pdev->dev.of_node); > + > dma_async_device_unregister(dma_dev); > > spin_lock_irq(&sh_dmae_lock); > -- > 1.7.2.5 > --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
