On Wed, Feb 29, 2012 at 03:54:08PM +0100, Nicolas Ferre wrote: > By making DMA controllers register a generic translation > function, we allow the management of any type of DMA requests > specification. > The void * output of an of_dma_xlate() function that will be implemented > by the DMA controller can carry any type of "dma-request" argument. > > The DMA client will search its associated DMA controller in the list > and call the registered of_dam_xlate() function to retrieve the > request values. > > One simple xlate function is provided for the "single number" type > of request biding. > > This implementation is independent from dmaengine so it can also be > used by legacy drivers. > > Signed-off-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx> > Cc: Benoit Cousson <b-cousson@xxxxxx> > Cc: Stephen Warren <swarren@xxxxxxxxxx> > Cc: Grant Likely <grant.likely@xxxxxxxxxxxx> > Cc: Russell King <linux@xxxxxxxxxxxxxxxx> > Cc: Rob Herring <rob.herring@xxxxxxxxxxx> > --- > Hi all, > > Here are my thoughts about the DMA helpers for device tree. > This patch goes on top of Benoit's ones. My goal was to keep this separated > from any DMA infrastructure (dmaengine not needed, nor any other DMA > implementation). > > It is to keep the ball rolling, so do not hesitate to comment. > > Best regards, > > > Documentation/devicetree/bindings/dma/dma.txt | 29 +++-- > drivers/of/dma.c | 161 ++++++++++++++++++++++--- > include/linux/of_dma.h | 33 +++++- > 3 files changed, 186 insertions(+), 37 deletions(-) > > diff --git a/Documentation/devicetree/bindings/dma/dma.txt b/Documentation/devicetree/bindings/dma/dma.txt > index 7f2a301..c49e98d 100644 > --- a/Documentation/devicetree/bindings/dma/dma.txt > +++ b/Documentation/devicetree/bindings/dma/dma.txt > @@ -6,9 +6,8 @@ DMA request line that goes from an IP to a DMA controller. > > * DMA controller > > -Required properties: > - - dma-controller: Mark the device as a DMA controller > - - #dma-cells: Number of cell for each DMA line, must be one. > +Required property: > + - #dma-cells: Number of cells for each DMA line. > > > Example: > @@ -17,7 +16,6 @@ Example: > compatible = "ti,sdma-omap4" > reg = <0x48000000 0x1000>; > interrupts = <12>; > - dma-controller; > #dma-cells = <1>; > }; > > @@ -25,20 +23,23 @@ Example: > > * DMA client > > -Client drivers should specify the DMA request numbers using a phandle to > -the controller + the DMA request number on that controller. > +Client drivers should specify the DMA request property using a phandle to > +the controller. If needed, the DMA request identity on that controller is then > +added followed by optional request specifications. > > -Required properties: > - - dma-request: List of pair phandle + dma-request per line > +Required property: > + - dma-request: List of phandle + dma-request + request specifications, > + one group per request "line". > +Optional property: > - dma-request-names: list of strings in the same order as the dma-request > in the dma-request property. > > > Example: > > - i2c1: i2c@1 { > - ... > - dma-request = <&sdma 2 &sdma 3>; > - dma-request-names = "tx", "rx"; > - ... > - }; > + i2c1: i2c@1 { > + ... > + dma-request = <&sdma 2 &sdma 3>; > + dma-request-names = "tx", "rx"; > + ... > + }; > diff --git a/drivers/of/dma.c b/drivers/of/dma.c > index d4927e2..e0c6fd9 100644 > --- a/drivers/of/dma.c > +++ b/drivers/of/dma.c > @@ -13,41 +13,145 @@ > #include <linux/device.h> > #include <linux/err.h> > #include <linux/module.h> > +#include <linux/rculist.h> > +#include <linux/slab.h> > #include <linux/of.h> > #include <linux/of_dma.h> > > +static LIST_HEAD(of_dma_list); > + > +/** > + * of_dma_find_controller() - Find a DMA controller in DT DMA helpers list > + * @np: device node of DMA controller > + */ > +static struct of_dma *of_dma_find_controller(struct device_node *np) > +{ > + struct of_dma *ofdma; > + > + list_for_each_entry_rcu(ofdma, &of_dma_list, of_dma_controllers) { > + if (ofdma->of_node == np) > + return ofdma; > + } > + > + return NULL; > +} > + > /** > - * of_get_dma_request() - Get a DMA request number and dma-controller node > + * of_dma_controller_register() - Register a DMA controller to DT DMA helpers > + * @np: device node of DMA controller > + * @of_dma_xlate: generic translation function which converts a phandle > + * arguments list into a generic output value > + * > + * Returns 0 on success or appropriate errno value on error. > + * > + * If #dma-cells is not specified in DMA controller device tree node, we assume > + * that the DMA controller phandle will come without argument. > + * > + * Allocated memory sould be freed with apropriate of_dma_controller_free() > + * call. > + */ > +int of_dma_controller_register(struct device_node *np, > + int (*of_dma_xlate)(struct of_phandle_args *, void *)) > +{ > + struct of_dma *ofdma; > + int *nbcells; > + > + if (!np || !of_dma_xlate) { > + pr_err("%s: not enouth information provided\n", __func__); > + return -EINVAL; > + } > + > + ofdma = kzalloc(sizeof(*ofdma), GFP_KERNEL); > + if (!ofdma) > + return -ENOMEM; > + > + nbcells = (int *)of_get_property(np, "#dma-cells", NULL); No cast required; but nbcells should be a (const __be32 *) instead of an int*. > + if (!nbcells) > + /* > + * no #dma-cells properties: assume no argument to > + * dma-request property on slave side > + */ > + ofdma->of_dma_n_cells = 0; > + else > + ofdma->of_dma_n_cells = be32_to_cpup(nbcells); > + > + ofdma->of_node = np; > + ofdma->of_dma_xlate = of_dma_xlate; > + > + /* Now queue of_dma controller structure in list */ > + list_add_tail_rcu(&ofdma->of_dma_controllers, &of_dma_list); > + > + return 0; > +} > +EXPORT_SYMBOL(of_dma_controller_register); EXPORT_SYMBOL_GPL > + > +/** > + * of_dma_controller_free() - Remove a DMA controller from DT DMA helpers list > + * @np: device node of DMA controller > + * > + * Memory allocated by of_dma_controller_register() is freed here. > + */ > +void of_dma_controller_free(struct device_node *np) > +{ > + struct of_dma *ofdma; > + > + ofdma = of_dma_find_controller(np); > + if (ofdma) { > + list_del_rcu(&ofdma->of_dma_controllers); > + kfree(ofdma); > + } > +} > +EXPORT_SYMBOL(of_dma_controller_free); > + > +/** > + * of_get_dma_request() - Get the associated DMA request data > * @np: device node to get DMA request from > - * @propname: property name containing DMA specifier(s) > * @index: index of the DMA request > - * @ctrl_np: a device_node pointer to fill in > + * @out_data: a output that can be filled in by the of_dma_xlate() function > * > - * Returns DMA number along to the dma controller node, or one of the errno > - * value on the error condition. If @ctrl_np is not NULL the function also > - * fills in the DMA controller device_node pointer. > + * Returns return value of of_dma_xlate() and fills out_data (if provided). > + * On error returns the appropriate errno value. > */ > int of_get_dma_request(struct device_node *np, int index, > - struct device_node **ctrl_np) > + void *out_data) > { > - int ret = -EINVAL; > - struct of_phandle_args dma_spec; > + struct of_phandle_args dma_spec; > + struct of_dma *ofdma; > + int ret; > > ret = of_parse_phandle_with_args(np, "dma-request", "#dma-cells", > index, &dma_spec); > if (ret) { > - pr_debug("%s: can't parse dma property\n", __func__); > + pr_err("%s: can't parse dma property\n", np->full_name); > goto err0; > } > > - if (dma_spec.args_count > 0) > - ret = dma_spec.args[0]; > + if (list_empty(&of_dma_list)) { > + pr_debug("%s: empty DMA controller list\n", > + np->full_name); > + ret = -ENOENT; > + goto err1; > + } > > - if (ctrl_np) > - *ctrl_np = dma_spec.np; > - else > - of_node_put(dma_spec.np); > + ofdma = of_dma_find_controller(dma_spec.np); > + if (!ofdma) { > + pr_debug("%s: DMA controller %s isn't registered\n", > + np->full_name, dma_spec.np->full_name); > + ret = -ENODEV; > + goto err1; > + } > > + if (dma_spec.args_count != ofdma->of_dma_n_cells) { > + pr_debug("%s: wrong #dma-cells for %s\n", > + np->full_name, dma_spec.np->full_name); > + ret = -EINVAL; > + goto err1; > + } > + > + ret = ofdma->of_dma_xlate(&dma_spec, out_data); > + > +err1: > + of_node_put(dma_spec.np); > err0: > pr_debug("%s exited with status %d\n", __func__, ret); > return ret; > @@ -55,6 +159,24 @@ err0: > EXPORT_SYMBOL(of_get_dma_request); > > /** > + * of_dma_xlate_onenumbercell() - Generic DMA xlate for direct one cell bindings > + * > + * Device Tree DMA translation function which works with one cell bindings > + * where the cell values map directly to the hardware request number understood > + * by the DMA controller. > + */ > +int of_dma_xlate_onenumbercell(struct of_phandle_args *dma_spec, void *req_nbr) > +{ > + if (!dma_spec) > + return -EINVAL; > + if (WARN_ON(dma_spec->args_count != 1)) > + return -EINVAL; > + *(int *)req_nbr = dma_spec->args[0]; > + return 0; > +} > +EXPORT_SYMBOL(of_dma_xlate_onenumbercell); > + > +/** > * of_dma_count - Count DMA requests for a device > * @np: device node to count DMAs for > * > @@ -105,13 +227,14 @@ int of_dma_to_resource(struct device_node *dev, int index, struct resource *r) > { > const char *name = NULL; > int dma; > + int ret; > > if (!r) > return -EINVAL; > > - dma = of_get_dma_request(dev, index, NULL); > - if (dma < 0) > - return dma; > + ret = of_get_dma_request(dev, index, &dma); > + if (ret < 0) > + return ret; > > /* > * Get optional "dma-request-names" property to add a name > diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h > index 575163d..fbf98de 100644 > --- a/include/linux/of_dma.h > +++ b/include/linux/of_dma.h > @@ -17,18 +17,38 @@ > > struct device_node; > > -#ifdef CONFIG_OF_GPIO > +#ifdef CONFIG_OF_DMA > > +struct of_dma { > + struct list_head of_dma_controllers; > + struct device_node *of_node; > + int of_dma_n_cells; > + int (*of_dma_xlate)(struct of_phandle_args *dma_spec, void *data); > +}; The api makes struct of_dma private; so this should be moved to the .c file. Otherwise, this looks okay to me. g. > + > +extern int of_dma_controller_register(struct device_node *np, > + int (*of_dma_xlate)(struct of_phandle_args *, void *)); > +extern void of_dma_controller_free(struct device_node *np); > extern int of_get_dma_request(struct device_node *np, int index, > - struct device_node **ctrl_np); > + void *out_data); > extern unsigned int of_dma_count(struct device_node *np); > extern int of_dma_to_resource(struct device_node *dev, int index, > struct resource *r); > > +extern int of_dma_xlate_onenumbercell(struct of_phandle_args *dma_spec, > + void *req_nbr); > #else /* CONFIG_OF_DMA */ > > -static int of_get_dma_request(struct device_node *np, int index, > - struct device_node **ctrl_np); > +static int of_dma_controller_register(struct device_node *np, > + int (*of_dma_xlate)(struct of_phandle_args *, void *)) > +{ > + return -ENOSYS; > +} > + > +static void of_dma_controller_free(struct device_node *np) {} > + > +extern int of_get_dma_request(struct device_node *np, int index, > + void *out_data) > { > return -ENOSYS; > } > @@ -44,6 +64,11 @@ static int of_dma_to_resource(struct device_node *dev, int index, > return -ENOSYS; > } > > +static int of_dma_xlate_onenumbercell(struct of_phandle_args *dma_spec, > + void *req_nbr) > +{ > + return -ENOSYS; > +} > #endif /* CONFIG_OF_DMA */ > > #endif /* __LINUX_OF_DMA_H */ > -- > 1.7.9 > -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html