Hi,
On Wed, Apr 08, 2015 at 04:14:45PM +0300, Peter Ujfalusi wrote:
> DMA routers are transparent devices used to mux DMA requests from
> peripherals to DMA controllers. They are used when the SoC integrates more
> devices with DMA requests then their controller can handle.
> DRA7x is one example of such SoC, where the sDMA can hanlde 128 DMA request
> lines, but in SoC level it has 205 DMA requests.
>
> The of_dma_router will be registered as of_dma_controller with special
> xlate function and additional parameters. The driver for the router is
> responsible to craft the dma_spec (in the of_dma_route_allocate callback)
> which can be used to requests a DMA channel from the real DMA controller.
> This way the router can be transparent for the system while remaining generic
> enough to be used in different environments.
>
> Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx>
> ---
> Documentation/devicetree/bindings/dma/dma.txt | 28 +++++++++
> drivers/dma/dmaengine.c | 7 +++
> drivers/dma/of-dma.c | 86 +++++++++++++++++++++++++++
> include/linux/dmaengine.h | 17 ++++++
> include/linux/of_dma.h | 21 +++++++
> 5 files changed, 159 insertions(+)
Can that be moved to a header / C file of its own?
There's a lot of various code already in dmaengine.h and dmaengine.c,
it would be really great to avoid adding more random stuff in there.
>
> diff --git a/Documentation/devicetree/bindings/dma/dma.txt b/Documentation/devicetree/bindings/dma/dma.txt
> index 82104271e754..6312fb00ce8d 100644
> --- a/Documentation/devicetree/bindings/dma/dma.txt
> +++ b/Documentation/devicetree/bindings/dma/dma.txt
> @@ -31,6 +31,34 @@ Example:
> dma-requests = <127>;
> };
>
> +* DMA router
> +
> +DMA routers are transparent IP blocks used to route DMA request lines from
> +devices to the DMA controller. Some SoCs (like TI DRA7x) have more peripherals
> +integrated with DMA requests than what the DMA controller can handle directly.
> +
> +Required property:
> +- dma-masters: phandle of the DMA controller or list of phandles for
> + the DMA controllers the router can direct the signal to.
> +- #dma-cells: Must be at least 1. Used to provide DMA router specific
> + information. See DMA client binding below for more
> + details.
> +
> +Optional properties:
> +- dma-requests: Number of incoming request lines the router can handle.
> +- In the node pointed by the dma-masters:
> + - dma-requests: The router driver might need to look for this in order
> + to configure the routing.
> +
> +Example:
> + sdma_xbar: dma-router@4a002b78 {
> + compatible = "ti,dra7-dma-crossbar";
> + reg = <0x4a002b78 0xfc>;
> + #dma-cells = <1>;
> + dma-requests = <205>;
> + ti,dma-safe-map = <0>;
> + dma-masters = <&sdma>;
> + };
>
> * DMA client
>
> diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
> index 24967c89f5d4..c7aa232b4a59 100644
> --- a/drivers/dma/dmaengine.c
> +++ b/drivers/dma/dmaengine.c
> @@ -267,6 +267,13 @@ static void dma_chan_put(struct dma_chan *chan)
> /* This channel is not in use anymore, free it */
> if (!chan->client_count && chan->device->device_free_chan_resources)
> chan->device->device_free_chan_resources(chan);
> +
> + /* If the channel is used via a DMA request router, free the mapping */
> + if (chan->router && chan->router->route_free) {
> + chan->router->route_free(chan->router->dev, chan->route_data);
> + chan->router = NULL;
> + chan->route_data = NULL;
> + }
> }
>
> enum dma_status dma_sync_wait(struct dma_chan *chan, dma_cookie_t cookie)
> diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
> index cbd4a8aff120..98b3b61624f0 100644
> --- a/drivers/dma/of-dma.c
> +++ b/drivers/dma/of-dma.c
> @@ -45,6 +45,47 @@ static struct of_dma *of_dma_find_controller(struct of_phandle_args *dma_spec)
> }
>
> /**
> + * of_dma_router_xlate - translation function for router devices
> + * @dma_spec: pointer to DMA specifier as found in the device tree
> + * @of_dma: pointer to DMA controller data (router information)
> + *
> + * The function creates new dma_spec to be passed to the router driver's
> + * of_dma_route_allocate() function to prepare a dma_spec which will be used
> + * to request channel from the real DMA controller.
> + */
> +static struct dma_chan *of_dma_router_xlate(struct of_phandle_args *dma_spec,
> + struct of_dma *ofdma)
> +{
> + struct dma_chan *chan;
> + struct of_dma *ofdma_target;
> + struct of_phandle_args dma_spec_target;
> + void *route_data;
> +
> + /* translate the request for the real DMA controller */
> + memcpy(&dma_spec_target, dma_spec, sizeof(dma_spec_target));
> + route_data = ofdma->of_dma_route_allocate(&dma_spec_target, ofdma);
> +
> + ofdma_target = of_dma_find_controller(&dma_spec_target);
> + if (!ofdma_target)
> + return NULL;
> +
> + chan = ofdma_target->of_dma_xlate(&dma_spec_target, ofdma_target);
> + if (chan) {
> + chan->router = ofdma->dma_router;
> + chan->route_data = route_data;
> + } else {
> + ofdma->dma_router->route_free(ofdma->dma_router->dev, route_data);
This line is over 80 characters.
> + }
> +
> + /*
> + * Need to put the node back since the ofdma->of_dma_route_allocate
> + * has taken it for generating the new, translated dma_spec
> + */
> + of_node_put(dma_spec_target.np);
> + return chan;
> +}
> +
> +/**
> * of_dma_controller_register - Register a DMA controller to DT DMA helpers
> * @np: device node of DMA controller
> * @of_dma_xlate: translation function which converts a phandle
> @@ -110,6 +151,51 @@ void of_dma_controller_free(struct device_node *np)
> EXPORT_SYMBOL_GPL(of_dma_controller_free);
>
> /**
> + * of_dma_router_register - Register a DMA router to DT DMA helpers as a
> + * controller
> + * @np: device node of DMA router
> + * @of_dma_route_allocate: setup function for the router which need to
> + * modify the dma_spec for the DMA controller to
> + * use and to set up the requested route.
> + * @dma_router: pointer to dma_router structure to be used when
> + * the route need to be free up.
> + *
> + * Returns 0 on success or appropriate errno value on error.
> + *
> + * Allocated memory should be freed with appropriate of_dma_controller_free()
> + * call.
> + */
> +int of_dma_router_register(struct device_node *np,
> + void *(*of_dma_route_allocate)
> + (struct of_phandle_args *, struct of_dma *),
> + struct dma_router *dma_router)
> +{
> + struct of_dma *ofdma;
> +
> + if (!np || !of_dma_route_allocate || !dma_router) {
> + pr_err("%s: not enough information provided\n", __func__);
> + return -EINVAL;
> + }
> +
> + ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL);
> + if (!ofdma)
> + return -ENOMEM;
Is that expected that you allocate through kzalloc, but never have a
matching free function implemented?
> + ofdma->of_node = np;
> + ofdma->of_dma_xlate = of_dma_router_xlate;
> + ofdma->of_dma_route_allocate = of_dma_route_allocate;
> + ofdma->dma_router = dma_router;
> +
> + /* Now queue of_dma controller structure in list */
> + mutex_lock(&of_dma_lock);
> + list_add_tail(&ofdma->of_dma_controllers, &of_dma_list);
> + mutex_unlock(&of_dma_lock);
> +
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(of_dma_router_register);
> +
> +/**
> * of_dma_match_channel - Check if a DMA specifier matches name
> * @np: device node to look for DMA channels
> * @name: channel name to be matched
> diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
> index ad419757241f..abf63ceabef9 100644
> --- a/include/linux/dmaengine.h
> +++ b/include/linux/dmaengine.h
> @@ -222,6 +222,16 @@ struct dma_chan_percpu {
> };
>
> /**
> + * struct dma_router - DMA router structure
> + * @dev: pointer to the DMA router device
> + * @route_free: function to be called when the route can be disconnected
> + */
> +struct dma_router {
> + struct device *dev;
> + void (*route_free)(struct device *dev, void *route_data);
> +};
> +
> +/**
> * struct dma_chan - devices supply DMA channels, clients use them
> * @device: ptr to the dma device who supplies this channel, always !%NULL
> * @cookie: last cookie value returned to client
> @@ -232,6 +242,8 @@ struct dma_chan_percpu {
> * @local: per-cpu pointer to a struct dma_chan_percpu
> * @client_count: how many clients are using this channel
> * @table_count: number of appearances in the mem-to-mem allocation table
> + * @router: pointer to the DMA router structure
> + * @route_data: channel specific data for the router
> * @private: private data for certain client-channel associations
> */
> struct dma_chan {
> @@ -247,6 +259,11 @@ struct dma_chan {
> struct dma_chan_percpu __percpu *local;
> int client_count;
> int table_count;
> +
> + /* DMA router */
> + struct dma_router *router;
> + void *route_data;
> +
> void *private;
> };
>
> diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h
> index 56bc026c143f..734e449f87c1 100644
> --- a/include/linux/of_dma.h
> +++ b/include/linux/of_dma.h
> @@ -23,6 +23,9 @@ struct of_dma {
> struct device_node *of_node;
> struct dma_chan *(*of_dma_xlate)
> (struct of_phandle_args *, struct of_dma *);
> + void *(*of_dma_route_allocate)
> + (struct of_phandle_args *, struct of_dma *);
> + struct dma_router *dma_router;
I don't really see why this is really tied to the device tree.
Couldn't we use the device_alloc_chan_resources to do that?
Thanks,
Maxime
--
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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