Channel allocation is slightly different in the slave DMA context,
client drivers typically need a channel from a particular DMA
controller only and even in some cases a specific channel is desired.
- To request a channel dma_request_channel() API is used.
+ To request a channel dma_request_chan() API is used.
Interface:
- struct dma_chan *dma_request_channel(dma_cap_mask_t mask,
- dma_filter_fn filter_fn,
- void *filter_param);
- where dma_filter_fn is defined as:
- typedef bool (*dma_filter_fn)(struct dma_chan *chan, void *filter_param);
-
- The 'filter_fn' parameter is optional, but highly recommended for
- slave and cyclic channels as they typically need to obtain a specific
- DMA channel.
-
- When the optional 'filter_fn' parameter is NULL, dma_request_channel()
- simply returns the first channel that satisfies the capability mask.
-
- Otherwise, the 'filter_fn' routine will be called once for each free
- channel which has a capability in 'mask'. 'filter_fn' is expected to
- return 'true' when the desired DMA channel is found.
+ struct dma_chan *dma_request_chan(struct device *dev, const char *name);
+
+ Which will find and return the 'name' DMA channel associated with the 'dev'
+ device. The association is done via DT, ACPI or board file based
+ dma_slave_map matching table.
A channel allocated via this interface is exclusive to the caller,
until dma_release_channel() is called.
#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>
}
EXPORT_SYMBOL_GPL(__dma_request_channel);
+static const struct dma_slave_map *dma_filter_match(struct dma_device *device,
+ const char *name,
+ struct device *dev)
+{
+ int i;
+
+ if (!device->filter.mapcnt)
+ return NULL;
+
+ for (i = 0; i < device->filter.mapcnt; i++) {
+ const struct dma_slave_map *map = &device->filter.map[i];
+
+ if (!strcmp(map->devname, dev_name(dev)) &&
+ !strcmp(map->slave, name))
+ return map;
+ }
+
+ return NULL;
+}
+
/**
- * dma_request_slave_channel_reason - try to allocate an exclusive slave channel
+ * dma_request_chan - try to allocate an exclusive slave channel
* @dev: pointer to client device structure
* @name: slave channel name
*
* Returns pointer to appropriate DMA channel on success or an error pointer.
*/
-struct dma_chan *dma_request_slave_channel_reason(struct device *dev,
- const char *name)
+struct dma_chan *dma_request_chan(struct device *dev, const char *name)
{
+ struct dma_device *d, *_d;
+ struct dma_chan *chan = NULL;
+
/* If device-tree is present get slave info from here */
if (dev->of_node)
- return of_dma_request_slave_channel(dev->of_node, name);
+ 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))
- return acpi_dma_request_slave_chan_by_name(dev, name);
+ if (has_acpi_companion(dev) && !chan)
+ chan = acpi_dma_request_slave_chan_by_name(dev, name);
+
+ if (chan) {
+ /* Valid channel found or requester need to be deferred */
+ if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER)
+ return chan;
+ }
+
+ /* Try to find the channel via the DMA filter map(s) */
+ mutex_lock(&dma_list_mutex);
+ list_for_each_entry_safe(d, _d, &dma_device_list, global_node) {
+ dma_cap_mask_t mask;
+ const struct dma_slave_map *map = dma_filter_match(d, name, dev);
+
+ if (!map)
+ continue;
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_SLAVE, mask);
- return ERR_PTR(-ENODEV);
+ chan = find_candidate(d, &mask, d->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_slave_channel_reason);
+EXPORT_SYMBOL_GPL(dma_request_chan);
/**
* dma_request_slave_channel - try to allocate an exclusive slave channel
struct dma_chan *dma_request_slave_channel(struct device *dev,
const char *name)
{
- struct dma_chan *ch = dma_request_slave_channel_reason(dev, name);
+ struct dma_chan *ch = dma_request_chan(dev, name);
if (IS_ERR(ch))
return NULL;
- dma_cap_set(DMA_PRIVATE, ch->device->cap_mask);
- ch->device->privatecnt++;
-
return ch;
}
EXPORT_SYMBOL_GPL(dma_request_slave_channel);
+/**
+ * dma_request_chan_by_mask - allocate a channel satisfying certain capabilities
+ * @mask: capabilities that the channel must satisfy
+ *
+ * Returns pointer to appropriate DMA channel on success or an error pointer.
+ */
+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);
DMAENGINE_ALIGN_64_BYTES = 6,
};
+/**
+ * struct dma_slave_map - associates slave device and it's slave channel with
+ * parameter to be used by a filter function
+ * @devname: name of the device
+ * @slave: slave channel name
+ * @param: opaque parameter to pass to struct dma_filter.fn
+ */
+struct dma_slave_map {
+ const char *devname;
+ const char *slave;
+ void *param;
+};
+
+/**
+ * struct dma_filter - information for slave device/channel to filter_fn/param
+ * mapping
+ * @fn: filter function callback
+ * @mapcnt: number of slave device/channel in the map
+ * @map: array of channel to filter mapping data
+ */
+struct dma_filter {
+ dma_filter_fn fn;
+ int mapcnt;
+ const struct dma_slave_map *map;
+};
+
/**
* struct dma_device - info on the entity supplying DMA services
* @chancnt: how many DMA channels are supported
* @privatecnt: how many DMA channels are requested by dma_request_channel
* @channels: the list of struct dma_chan
* @global_node: list_head for global dma_device_list
+ * @filter: information for device/slave to filter function/param mapping
* @cap_mask: one or more dma_capability flags
* @max_xor: maximum number of xor sources, 0 if no capability
* @max_pq: maximum number of PQ sources and PQ-continue capability
unsigned int privatecnt;
struct list_head channels;
struct list_head global_node;
+ struct dma_filter filter;
dma_cap_mask_t cap_mask;
unsigned short max_xor;
unsigned short max_pq;
void dma_issue_pending_all(void);
struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
dma_filter_fn fn, void *fn_param);
-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
{
return NULL;
}
-static inline struct dma_chan *dma_request_slave_channel_reason(
- struct device *dev, const char *name)
-{
- return ERR_PTR(-ENODEV);
-}
static inline struct dma_chan *dma_request_slave_channel(struct device *dev,
const char *name)
{
return NULL;
}
+static inline struct dma_chan *dma_request_chan(struct device *dev,
+ const char *name)
+{
+ 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)
{
}
}
#endif
+#define dma_request_slave_channel_reason(dev, name) dma_request_chan(dev, name)
+
static inline int dmaengine_desc_set_reuse(struct dma_async_tx_descriptor *tx)
{
struct dma_slave_caps caps;
projects / GitHub / moto-9609 / android_kernel_motorola_exynos9610.git / commitdiff