[RFC v2 PATCH] at_hdmac: move to generic DMA binding
Jean-Christophe PLAGNIOL-VILLARD
plagnioj at jcrosoft.com
Mon Apr 8 06:55:15 EDT 2013
On 08:43 Mon 08 Apr , ludovic.desroches at atmel.com wrote:
> From: Ludovic Desroches <ludovic.desroches at atmel.com>
>
> Signed-off-by: Ludovic Desroches <ludovic.desroches at atmel.com>
> ---
>
> Hi,
>
> Here is a second try to move at_hdmac to generic DMA binding. I have updated
> bindings according to Arnd comments ie I have removed chunk transfer size.
>
> I have added the implementation but I am not very happy with the translation
> function. I have tried to not break old stuff: slave ask for a channel giving
> an atslave structure (passed through pdata) as a parameter for the filter
> function which saves this structure into chan->private. Then chan->private
> contains the configuration for the channel CFG register which is done when
> calling device_alloc_chan_resources.
>
> If I allocate the atslave structure in the xlate function, where should be the
> right place to deallocate it? For the moment, I choose to add the atslave
> structure to the at_dma_chan structure but I am not happy with writing the
> channel configuration register into the xlate function. I would like to keep
> the same path as before.
so allow with devm_
>
> Regards
>
> Ludovic
>
>
> .../devicetree/bindings/dma/atmel-dma.txt | 27 +++++++-
> arch/arm/boot/dts/sama5d3.dtsi | 2 +
> drivers/dma/at_hdmac.c | 71 ++++++++++++++++++++--
> drivers/dma/at_hdmac_regs.h | 7 +++
> 4 files changed, 99 insertions(+), 8 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/dma/atmel-dma.txt b/Documentation/devicetree/bindings/dma/atmel-dma.txt
> index 3c046ee..2d6f0f3 100644
> --- a/Documentation/devicetree/bindings/dma/atmel-dma.txt
> +++ b/Documentation/devicetree/bindings/dma/atmel-dma.txt
> @@ -4,11 +4,34 @@ Required properties:
> - compatible: Should be "atmel,<chip>-dma"
> - reg: Should contain DMA registers location and length
> - interrupts: Should contain DMA interrupt
> +- #dma-cells: Must be <2>
>
> -Examples:
> +Example:
>
> -dma at ffffec00 {
> +dma0: dma at ffffec00 {
> compatible = "atmel,at91sam9g45-dma";
> reg = <0xffffec00 0x200>;
> interrupts = <21>;
> + #dma-cells = <2>;
> +};
> +
> +DMA clients connected to the Atmel DMA controller must use the format
> +described in the dma.txt file, using a three-cell specifier for each channel.
> +The three cells in order are:
> +
> +1. A phandle pointing to the DMA controller
> +2. The memory interface (16 most significant bits), the peripheral interface
> +(16 less significant bits)
> +3. The peripheral identifier (can be different for tx and rx)
> +
> +Example:
> +
> +i2c0 at i2c@f8010000 {
> + compatible = "atmel,at91sam9x5-i2c";
> + reg = <0xf8010000 0x100>;
> + interrupts = <9 4 6>;
> + dmas = <&dma0 1 7>,
> + <&dma0 1 8>;
> + dma-names = "tx", "rx"
> };
> diff --git a/arch/arm/boot/dts/sama5d3.dtsi b/arch/arm/boot/dts/sama5d3.dtsi
> index 39b0458..9232143 100644
> --- a/arch/arm/boot/dts/sama5d3.dtsi
> +++ b/arch/arm/boot/dts/sama5d3.dtsi
> @@ -349,6 +349,7 @@
> reg = <0xffffe600 0x200>;
> interrupts = <30 4 0>;
> #dma-cells = <1>;
> + #dma-cells = <2>;
??
2 dma-cells?
> };
>
> dma1: dma-controller at ffffe800 {
> @@ -356,6 +357,7 @@
> reg = <0xffffe800 0x200>;
> interrupts = <31 4 0>;
> #dma-cells = <1>;
> + #dma-cells = <2>;
ditto
> };
>
> ramc0: ramc at ffffea00 {
> diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
> index 8415467..ec7f561 100644
> --- a/drivers/dma/at_hdmac.c
> +++ b/drivers/dma/at_hdmac.c
> @@ -24,6 +24,7 @@
> #include <linux/slab.h>
> #include <linux/of.h>
> #include <linux/of_device.h>
> +#include <linux/of_dma.h>
>
> #include "at_hdmac_regs.h"
> #include "dmaengine.h"
> @@ -676,7 +677,7 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> ctrlb |= ATC_DST_ADDR_MODE_FIXED
> | ATC_SRC_ADDR_MODE_INCR
> | ATC_FC_MEM2PER
> - | ATC_SIF(AT_DMA_MEM_IF) | ATC_DIF(AT_DMA_PER_IF);
> + | ATC_SIF(atchan->mem_if) | ATC_DIF(atchan->per_if);
> reg = sconfig->dst_addr;
> for_each_sg(sgl, sg, sg_len, i) {
> struct at_desc *desc;
> @@ -715,7 +716,7 @@ atc_prep_slave_sg(struct dma_chan *chan, struct scatterlist *sgl,
> ctrlb |= ATC_DST_ADDR_MODE_INCR
> | ATC_SRC_ADDR_MODE_FIXED
> | ATC_FC_PER2MEM
> - | ATC_SIF(AT_DMA_PER_IF) | ATC_DIF(AT_DMA_MEM_IF);
> + | ATC_SIF(atchan->per_if) | ATC_DIF(atchan->mem_if);
>
> reg = sconfig->src_addr;
> for_each_sg(sgl, sg, sg_len, i) {
> @@ -821,8 +822,8 @@ atc_dma_cyclic_fill_desc(struct dma_chan *chan, struct at_desc *desc,
> desc->lli.ctrlb = ATC_DST_ADDR_MODE_FIXED
> | ATC_SRC_ADDR_MODE_INCR
> | ATC_FC_MEM2PER
> - | ATC_SIF(AT_DMA_MEM_IF)
> - | ATC_DIF(AT_DMA_PER_IF);
> + | ATC_SIF(atchan->mem_if)
> + | ATC_DIF(atchan->per_if);
> break;
>
> case DMA_DEV_TO_MEM:
> @@ -832,8 +833,8 @@ atc_dma_cyclic_fill_desc(struct dma_chan *chan, struct at_desc *desc,
> desc->lli.ctrlb = ATC_DST_ADDR_MODE_INCR
> | ATC_SRC_ADDR_MODE_FIXED
> | ATC_FC_PER2MEM
> - | ATC_SIF(AT_DMA_PER_IF)
> - | ATC_DIF(AT_DMA_MEM_IF);
> + | ATC_SIF(atchan->per_if)
> + | ATC_DIF(atchan->mem_if);
> break;
>
> default:
> @@ -1189,6 +1190,55 @@ static void atc_free_chan_resources(struct dma_chan *chan)
> dev_vdbg(chan2dev(chan), "free_chan_resources: done\n");
> }
>
> +static bool at_dma_filter(struct dma_chan *chan, void *dma_dev)
> +{
> + if (dma_dev == chan->device->dev)
> + return true;
> + else
> + return false;
> +}
> +
> +static struct dma_chan *at_dma_xlate(struct of_phandle_args *dma_spec,
> + struct of_dma *of_dma)
> +{
> + struct dma_chan *chan;
> + struct at_dma_chan *atchan;
> + struct at_dma_slave *atslave;
> + dma_cap_mask_t mask;
> + unsigned int per_id;
> + struct platform_device *dmac_pdev;
> +
> + if (dma_spec->args_count != 2)
> + return NULL;
> +
> + dmac_pdev = of_find_device_by_node(dma_spec->np);
> +
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_SLAVE, mask);
> +
> + chan = dma_request_channel(mask, at_dma_filter, &dmac_pdev->dev);
> + if (!chan)
> + return NULL;
> +
> + atchan = to_at_dma_chan(chan);
> + atchan->per_if = dma_spec->args[0] & 0xff;
> + atchan->mem_if = (dma_spec->args[0] >> 16) & 0xff;
> +
> + atslave = &atchan->atslave;
> + /*
> + * We can fill both SRC_PER and DST_PER, one of these fields will be
> + * ignored depending on DMA transfer direction.
> + */
> + per_id = dma_spec->args[1];
> + atslave->cfg = ATC_FIFOCFG_HALFFIFO | ATC_DST_H2SEL_HW
> + | ATC_SRC_H2SEL_HW | ATC_DST_PER(per_id)
> + | ATC_SRC_PER(per_id);
> + atslave->dma_dev = &dmac_pdev->dev;
> + chan->private = atslave;
> + channel_writel(atchan, CFG, atslave->cfg);
> +
> + return chan;
> +}
>
> /*-- Module Management -----------------------------------------------*/
>
> @@ -1389,6 +1439,15 @@ static int __init at_dma_probe(struct platform_device *pdev)
>
> dma_async_device_register(&atdma->dma_common);
>
> + if (pdev->dev.of_node) {
more simple return if NULL
> + printk("=== of_dma_controller_register ===\n");
drop this
> + err = of_dma_controller_register(pdev->dev.of_node,
> + at_dma_xlate, atdma);
> + if (err && err != -ENODEV)
> + dev_err(&pdev->dev,
> + "could not register of_dma_controller\n");
if err you need to return err
> + }
> +
> return 0;
>
> err_pool_create:
> diff --git a/drivers/dma/at_hdmac_regs.h b/drivers/dma/at_hdmac_regs.h
> index 0eb3c13..e3d2f12 100644
> --- a/drivers/dma/at_hdmac_regs.h
> +++ b/drivers/dma/at_hdmac_regs.h
> @@ -220,6 +220,8 @@ enum atc_status {
> * @device: parent device
> * @ch_regs: memory mapped register base
> * @mask: channel index in a mask
> + * @per_if: peripheral interface
> + * @mem_if: memory interface
> * @status: transmit status information from irq/prep* functions
> * to tasklet (use atomic operations)
> * @tasklet: bottom half to finish transaction work
> @@ -227,6 +229,8 @@ enum atc_status {
> * @save_dscr: for cyclic operations, preserve next descriptor address in
> * the cyclic list on suspend/resume cycle
> * @dma_sconfig: configuration for slave transfers, passed via DMA_SLAVE_CONFIG
> + * @atslave: hardware configuration for slave transfers which is not passed via
> + * DMA_SLAVE_CONFIG
> * @lock: serializes enqueue/dequeue operations to descriptors lists
> * @active_list: list of descriptors dmaengine is being running on
> * @queue: list of descriptors ready to be submitted to engine
> @@ -238,11 +242,14 @@ struct at_dma_chan {
> struct at_dma *device;
> void __iomem *ch_regs;
> u8 mask;
> + u8 per_if;
> + u8 mem_if;
> unsigned long status;
> struct tasklet_struct tasklet;
> u32 save_cfg;
> u32 save_dscr;
> struct dma_slave_config dma_sconfig;
> + struct at_dma_slave atslave;
>
> spinlock_t lock;
>
> --
> 1.7.11.3
>
More information about the linux-arm-kernel
mailing list