The two API function can cover most, if not all current APIs used to request a channel. With minimal effort dmaengine drivers, platforms and dmaengine user drivers can be converted to use the two function. struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask); To request any channel matching with the requested capabilities, can be used to request channel for memcpy, memset, xor, etc where no hardware synchronization is needed. struct dma_chan *dma_request_chan(struct device *dev, const char *name); To request a slave channel. The dma_request_chan() will try to find the channel via DT, ACPI or in case if the kernel booted in non DT/ACPI mode it will use a filter lookup table and retrieves the needed information from the dma_filter_map provided by the DMA drivers. This legacy mode needs changes in platform code, in dmaengine drivers and finally the dmaengine user drivers can be converted: For each dmaengine driver an array of DMA device, slave and the parameter for the filter function needs to be added: static struct dma_filter_map da830_edma_map[] = { DMA_FILTER_ENTRY("davinci-mcasp.0", "rx", EDMA_CTLR_CHAN(0, 0)), DMA_FILTER_ENTRY("davinci-mcasp.0", "tx", EDMA_CTLR_CHAN(0, 1)), DMA_FILTER_ENTRY("davinci-mcasp.1", "rx", EDMA_CTLR_CHAN(0, 2)), DMA_FILTER_ENTRY("davinci-mcasp.1", "tx", EDMA_CTLR_CHAN(0, 3)), DMA_FILTER_ENTRY("davinci-mcasp.2", "rx", EDMA_CTLR_CHAN(0, 4)), DMA_FILTER_ENTRY("davinci-mcasp.2", "tx", EDMA_CTLR_CHAN(0, 5)), DMA_FILTER_ENTRY("spi_davinci.0", "rx", EDMA_CTLR_CHAN(0, 14)), DMA_FILTER_ENTRY("spi_davinci.0", "tx", EDMA_CTLR_CHAN(0, 15)), DMA_FILTER_ENTRY("da830-mmc.0", "rx", EDMA_CTLR_CHAN(0, 16)), DMA_FILTER_ENTRY("da830-mmc.0", "tx", EDMA_CTLR_CHAN(0, 17)), DMA_FILTER_ENTRY("spi_davinci.1", "rx", EDMA_CTLR_CHAN(0, 18)), DMA_FILTER_ENTRY("spi_davinci.1", "tx", EDMA_CTLR_CHAN(0, 19)), }; This information is going to be needed by the dmaengine driver, so modification to the platform_data is needed, and the driver map should be added to the pdata of the DMA driver: da8xx_edma0_pdata.filter_map = da830_edma_map; da8xx_edma0_pdata.filtercnt = ARRAY_SIZE(da830_edma_map); The DMA driver then needs to convigure the needed device -> filter_fn mapping before it registers with dma_async_device_register() : if (info->filter_map) { ecc->dma_slave.filter_map.map = info->filter_map; ecc->dma_slave.filter_map.mapcnt = info->filtercnt; ecc->dma_slave.filter_map.filter_fn = edma_filter_for_map; } When neither DT or ACPI lookup is available the dma_request_chan() will try to match the requester's device name with the filter_map's list of device names, when a match found it will use the information from the dma_filter_map to get the channel with the dma_get_channel() internal function. Signed-off-by: Peter Ujfalusi <peter.ujfalusi@xxxxxx> --- drivers/dma/dmaengine.c | 76 +++++++++++++++++++++++++++++++++++++++++++++++ include/linux/dmaengine.h | 31 +++++++++++++++++++ 2 files changed, 107 insertions(+) diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index 1249165fb4b2..bd774adff697 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -43,6 +43,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/platform_device.h> #include <linux/dma-mapping.h> #include <linux/init.h> #include <linux/module.h> @@ -715,6 +716,81 @@ struct dma_chan *dma_request_slave_channel(struct device *dev, } EXPORT_SYMBOL_GPL(dma_request_slave_channel); +static struct dma_filter_map *dma_filter_match(struct dma_device *device, + const char *name, + struct device *dev) +{ + struct dma_filter_map *map_found = NULL; + int i; + + if (!device->filter_map.mapcnt) + return NULL; + + for (i = 0; i < device->filter_map.mapcnt; i++) { + struct dma_filter_map *map = &device->filter_map.map[i]; + + if (!strcmp(map->devname, dev_name(dev)) && + !strcmp(map->slave, name)) { + map_found = map; + break; + } + } + + return map_found; +} + +struct dma_chan *dma_request_chan(struct device *dev, const char *name) +{ + struct dma_device *device, *_d; + struct dma_chan *chan = NULL; + + /* If device-tree is present get slave info from here */ + if (dev->of_node) + chan = of_dma_request_slave_channel(dev->of_node, name); + + /* If device was enumerated by ACPI get slave info from here */ + if (ACPI_HANDLE(dev) && !chan) + chan = acpi_dma_request_slave_chan_by_name(dev, name); + + if (chan) + return chan; + + /* Try to find the channel via the DMA filter map(s) */ + mutex_lock(&dma_list_mutex); + list_for_each_entry_safe(device, _d, &dma_device_list, global_node) { + struct dma_filter_map *map = dma_filter_match(device, name, + dev); + + if (!map) + continue; + + chan = dma_get_channel(device, NULL, + device->filter_map.filter_fn, + map->param); + if (!IS_ERR(chan)) + break; + } + mutex_unlock(&dma_list_mutex); + + return chan ? chan : ERR_PTR(-EPROBE_DEFER); +} +EXPORT_SYMBOL_GPL(dma_request_chan); + +struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask) +{ + struct dma_chan *chan; + + if (!mask) + return ERR_PTR(-ENODEV); + + chan = __dma_request_channel(mask, NULL, NULL); + if (!chan) + chan = ERR_PTR(-ENODEV); + + return chan; +} +EXPORT_SYMBOL_GPL(dma_request_chan_by_mask); + void dma_release_channel(struct dma_chan *chan) { mutex_lock(&dma_list_mutex); diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index a2b7c2071cf4..f7b06ff982c8 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -606,6 +606,24 @@ enum dmaengine_alignment { DMAENGINE_ALIGN_64_BYTES = 6, }; +struct dma_filter_map { + char *devname; + char *slave; + void *param; +}; +#define DMA_FILTER_ENTRY(_devname, _slave, _param) \ + { \ + .devname = _devname, \ + .slave = _slave, \ + .param = (void*)_param, \ + } + +struct dma_filter { + dma_filter_fn filter_fn; + int mapcnt; + struct dma_filter_map *map; +}; + /** * struct dma_device - info on the entity supplying DMA services * @chancnt: how many DMA channels are supported @@ -669,6 +687,7 @@ struct dma_device { unsigned int privatecnt; struct list_head channels; struct list_head global_node; + struct dma_filter filter_map; dma_cap_mask_t cap_mask; unsigned short max_xor; unsigned short max_pq; @@ -1235,6 +1254,10 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask, struct dma_chan *dma_request_slave_channel_reason(struct device *dev, const char *name); struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name); + +struct dma_chan *dma_request_chan(struct device *dev, const char *name); +struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask); + void dma_release_channel(struct dma_chan *chan); int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps); #else @@ -1268,6 +1291,14 @@ static inline struct dma_chan *dma_request_slave_channel(struct device *dev, { return NULL; } +static inline struct dma_chan *dma_request_chan(struct device *dev) +{ + return ERR_PTR(-ENODEV); +} +static inline struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask) +{ + return ERR_PTR(-ENODEV); +} static inline void dma_release_channel(struct dma_chan *chan) { } -- 2.6.3 -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html