Commit a8135d0d authored by Peter Ujfalusi's avatar Peter Ujfalusi Committed by Vinod Koul

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: default avatarPeter Ujfalusi <peter.ujfalusi@ti.com>
Reviewed-by: default avatarArnd Bergmann <arnd@arndb.de>
Signed-off-by: default avatarVinod Koul <vinod.koul@intel.com>
parent 7bd903c5
......@@ -22,25 +22,14 @@ The slave DMA usage consists of following steps:
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.
......
......@@ -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>
......@@ -665,27 +666,73 @@ struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
}
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);
return ERR_PTR(-ENODEV);
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);
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
......@@ -697,17 +744,35 @@ EXPORT_SYMBOL_GPL(dma_request_slave_channel_reason);
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);
......
......@@ -606,12 +606,39 @@ enum dmaengine_alignment {
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
......@@ -666,6 +693,7 @@ struct dma_device {
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;
......@@ -1140,9 +1168,11 @@ enum dma_status dma_wait_for_async_tx(struct dma_async_tx_descriptor *tx);
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
......@@ -1166,16 +1196,21 @@ static inline struct dma_chan *__dma_request_channel(const dma_cap_mask_t *mask,
{
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)
{
}
......@@ -1186,6 +1221,8 @@ static inline int dma_get_slave_caps(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;
......
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