dmaengine: core: Introduce new, universal API to request a channel
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_slave_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 const struct dma_slave_map da830_edma_map[] = {
{ "davinci-mcasp.0", "rx", EDMA_FILTER_PARAM(0, 0) },
{ "davinci-mcasp.0", "tx", EDMA_FILTER_PARAM(0, 1) },
{ "davinci-mcasp.1", "rx", EDMA_FILTER_PARAM(0, 2) },
{ "davinci-mcasp.1", "tx", EDMA_FILTER_PARAM(0, 3) },
{ "davinci-mcasp.2", "rx", EDMA_FILTER_PARAM(0, 4) },
{ "davinci-mcasp.2", "tx", EDMA_FILTER_PARAM(0, 5) },
{ "spi_davinci.0", "rx", EDMA_FILTER_PARAM(0, 14) },
{ "spi_davinci.0", "tx", EDMA_FILTER_PARAM(0, 15) },
{ "da830-mmc.0", "rx", EDMA_FILTER_PARAM(0, 16) },
{ "da830-mmc.0", "tx", EDMA_FILTER_PARAM(0, 17) },
{ "spi_davinci.1", "rx", EDMA_FILTER_PARAM(0, 18) },
{ "spi_davinci.1", "tx", EDMA_FILTER_PARAM(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.slave_map = da830_edma_map;
da8xx_edma0_pdata.slavecnt = ARRAY_SIZE(da830_edma_map);
The DMA driver then needs to configure the needed device -> filter_fn
mapping before it registers with dma_async_device_register() :
ecc->dma_slave.filter_map.map = info->slave_map;
ecc->dma_slave.filter_map.mapcnt = info->slavecnt;
ecc->dma_slave.filter_map.fn = edma_filter_fn;
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_slave_map to get the channel with the dma_get_channel() internal
function.
Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
This commit is contained in:
Peter Ujfalusi
Vinod Koul
Родитель
7bd903c5ca
Коммит
a8135d0d79
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@ -22,25 +22,14 @@ The slave DMA usage consists of following steps:
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Channel allocation is slightly different in the slave DMA context,
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client drivers typically need a channel from a particular DMA
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controller only and even in some cases a specific channel is desired.
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To request a channel dma_request_channel() API is used.
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To request a channel dma_request_chan() API is used.
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Interface:
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struct dma_chan *dma_request_channel(dma_cap_mask_t mask,
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dma_filter_fn filter_fn,
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void *filter_param);
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where dma_filter_fn is defined as:
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typedef bool (*dma_filter_fn)(struct dma_chan *chan, void *filter_param);
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struct dma_chan *dma_request_chan(struct device *dev, const char *name);
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The 'filter_fn' parameter is optional, but highly recommended for
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slave and cyclic channels as they typically need to obtain a specific
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DMA channel.
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When the optional 'filter_fn' parameter is NULL, dma_request_channel()
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simply returns the first channel that satisfies the capability mask.
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Otherwise, the 'filter_fn' routine will be called once for each free
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channel which has a capability in 'mask'. 'filter_fn' is expected to
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return 'true' when the desired DMA channel is found.
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Which will find and return the 'name' DMA channel associated with the 'dev'
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device. The association is done via DT, ACPI or board file based
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dma_slave_map matching table.
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A channel allocated via this interface is exclusive to the caller,
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until dma_release_channel() is called.
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@ -43,6 +43,7 @@
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/platform_device.h>
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#include <linux/dma-mapping.h>
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#include <linux/init.h>
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#include <linux/module.h>
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@ -665,27 +666,73 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
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}
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EXPORT_SYMBOL_GPL(__dma_request_channel);
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static const struct dma_slave_map *dma_filter_match(struct dma_device *device,
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const char *name,
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struct device *dev)
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{
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int i;
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if (!device->filter.mapcnt)
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return NULL;
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for (i = 0; i < device->filter.mapcnt; i++) {
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const struct dma_slave_map *map = &device->filter.map[i];
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if (!strcmp(map->devname, dev_name(dev)) &&
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!strcmp(map->slave, name))
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return map;
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}
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return NULL;
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}
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/**
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* dma_request_slave_channel_reason - try to allocate an exclusive slave channel
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* dma_request_chan - try to allocate an exclusive slave channel
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* @dev: pointer to client device structure
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* @name: slave channel name
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*
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* Returns pointer to appropriate DMA channel on success or an error pointer.
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*/
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struct dma_chan *dma_request_slave_channel_reason(struct device *dev,
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const char *name)
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struct dma_chan *dma_request_chan(struct device *dev, const char *name)
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{
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struct dma_device *d, *_d;
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struct dma_chan *chan = NULL;
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/* If device-tree is present get slave info from here */
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if (dev->of_node)
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return of_dma_request_slave_channel(dev->of_node, name);
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chan = of_dma_request_slave_channel(dev->of_node, name);
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/* If device was enumerated by ACPI get slave info from here */
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if (ACPI_HANDLE(dev))
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return acpi_dma_request_slave_chan_by_name(dev, name);
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if (has_acpi_companion(dev) && !chan)
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chan = acpi_dma_request_slave_chan_by_name(dev, name);
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return ERR_PTR(-ENODEV);
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if (chan) {
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/* Valid channel found or requester need to be deferred */
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if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER)
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return chan;
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}
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/* Try to find the channel via the DMA filter map(s) */
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mutex_lock(&dma_list_mutex);
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list_for_each_entry_safe(d, _d, &dma_device_list, global_node) {
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dma_cap_mask_t mask;
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const struct dma_slave_map *map = dma_filter_match(d, name, dev);
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if (!map)
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continue;
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dma_cap_zero(mask);
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dma_cap_set(DMA_SLAVE, mask);
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chan = find_candidate(d, &mask, d->filter.fn, map->param);
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if (!IS_ERR(chan))
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break;
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}
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mutex_unlock(&dma_list_mutex);
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return chan ? chan : ERR_PTR(-EPROBE_DEFER);
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}
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EXPORT_SYMBOL_GPL(dma_request_slave_channel_reason);
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EXPORT_SYMBOL_GPL(dma_request_chan);
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/**
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* dma_request_slave_channel - try to allocate an exclusive slave channel
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@ -697,17 +744,35 @@ EXPORT_SYMBOL_GPL(dma_request_slave_channel_reason);
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struct dma_chan *dma_request_slave_channel(struct device *dev,
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const char *name)
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{
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struct dma_chan *ch = dma_request_slave_channel_reason(dev, name);
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struct dma_chan *ch = dma_request_chan(dev, name);
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if (IS_ERR(ch))
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return NULL;
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dma_cap_set(DMA_PRIVATE, ch->device->cap_mask);
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ch->device->privatecnt++;
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return ch;
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}
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EXPORT_SYMBOL_GPL(dma_request_slave_channel);
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/**
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* dma_request_chan_by_mask - allocate a channel satisfying certain capabilities
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* @mask: capabilities that the channel must satisfy
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*
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* Returns pointer to appropriate DMA channel on success or an error pointer.
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*/
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struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask)
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{
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struct dma_chan *chan;
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if (!mask)
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return ERR_PTR(-ENODEV);
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chan = __dma_request_channel(mask, NULL, NULL);
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if (!chan)
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chan = ERR_PTR(-ENODEV);
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return chan;
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}
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EXPORT_SYMBOL_GPL(dma_request_chan_by_mask);
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void dma_release_channel(struct dma_chan *chan)
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{
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mutex_lock(&dma_list_mutex);
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@ -606,12 +606,39 @@ enum dmaengine_alignment {
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DMAENGINE_ALIGN_64_BYTES = 6,
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};
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/**
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* struct dma_slave_map - associates slave device and it's slave channel with
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* parameter to be used by a filter function
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* @devname: name of the device
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* @slave: slave channel name
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* @param: opaque parameter to pass to struct dma_filter.fn
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*/
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struct dma_slave_map {
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const char *devname;
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const char *slave;
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void *param;
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};
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/**
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* struct dma_filter - information for slave device/channel to filter_fn/param
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* mapping
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* @fn: filter function callback
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* @mapcnt: number of slave device/channel in the map
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* @map: array of channel to filter mapping data
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*/
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struct dma_filter {
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dma_filter_fn fn;
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int mapcnt;
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const struct dma_slave_map *map;
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};
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/**
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* struct dma_device - info on the entity supplying DMA services
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* @chancnt: how many DMA channels are supported
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* @privatecnt: how many DMA channels are requested by dma_request_channel
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* @channels: the list of struct dma_chan
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* @global_node: list_head for global dma_device_list
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* @filter: information for device/slave to filter function/param mapping
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* @cap_mask: one or more dma_capability flags
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* @max_xor: maximum number of xor sources, 0 if no capability
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* @max_pq: maximum number of PQ sources and PQ-continue capability
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@ -666,6 +693,7 @@ struct dma_device {
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unsigned int privatecnt;
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struct list_head channels;
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struct list_head global_node;
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struct dma_filter filter;
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dma_cap_mask_t cap_mask;
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unsigned short max_xor;
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unsigned short max_pq;
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@ -1140,9 +1168,11 @@ enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
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void dma_issue_pending_all(void);
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struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
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dma_filter_fn fn, void *fn_param);
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struct dma_chan *dma_request_slave_channel_reason(struct device *dev,
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const char *name);
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struct dma_chan *dma_request_slave_channel(struct device *dev, const char *name);
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struct dma_chan *dma_request_chan(struct device *dev, const char *name);
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struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask);
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void dma_release_channel(struct dma_chan *chan);
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int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps);
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#else
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@ -1166,16 +1196,21 @@ static inline struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
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{
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return NULL;
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}
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static inline struct dma_chan *dma_request_slave_channel_reason(
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struct device *dev, const char *name)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline struct dma_chan *dma_request_slave_channel(struct device *dev,
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const char *name)
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{
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return NULL;
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}
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static inline struct dma_chan *dma_request_chan(struct device *dev,
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const char *name)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline struct dma_chan *dma_request_chan_by_mask(
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const dma_cap_mask_t *mask)
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{
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return ERR_PTR(-ENODEV);
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}
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static inline void dma_release_channel(struct dma_chan *chan)
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{
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}
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@ -1186,6 +1221,8 @@ static inline int dma_get_slave_caps(struct dma_chan *chan,
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}
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#endif
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#define dma_request_slave_channel_reason(dev, name) dma_request_chan(dev, name)
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static inline int dmaengine_desc_set_reuse(struct dma_async_tx_descriptor *tx)
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{
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struct dma_slave_caps caps;
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