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335 lines
12 KiB
335 lines
12 KiB
From a8135d0d79e9d0ad3a4ff494fceeaae838becf38 Mon Sep 17 00:00:00 2001
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From: Peter Ujfalusi <peter.ujfalusi@ti.com>
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Date: Mon, 14 Dec 2015 22:47:40 +0200
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Subject: [PATCH 2/3] dmaengine: core: Introduce new, universal API to request
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a channel
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The two API function can cover most, if not all current APIs used to
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request a channel. With minimal effort dmaengine drivers, platforms and
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dmaengine user drivers can be converted to use the two function.
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struct dma_chan *dma_request_chan_by_mask(const dma_cap_mask_t *mask);
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To request any channel matching with the requested capabilities, can be
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used to request channel for memcpy, memset, xor, etc where no hardware
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synchronization is needed.
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struct dma_chan *dma_request_chan(struct device *dev, const char *name);
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To request a slave channel. The dma_request_chan() will try to find the
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channel via DT, ACPI or in case if the kernel booted in non DT/ACPI mode
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it will use a filter lookup table and retrieves the needed information from
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the dma_slave_map provided by the DMA drivers.
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This legacy mode needs changes in platform code, in dmaengine drivers and
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finally the dmaengine user drivers can be converted:
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For each dmaengine driver an array of DMA device, slave and the parameter
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for the filter function needs to be added:
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static const struct dma_slave_map da830_edma_map[] = {
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{ "davinci-mcasp.0", "rx", EDMA_FILTER_PARAM(0, 0) },
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{ "davinci-mcasp.0", "tx", EDMA_FILTER_PARAM(0, 1) },
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{ "davinci-mcasp.1", "rx", EDMA_FILTER_PARAM(0, 2) },
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{ "davinci-mcasp.1", "tx", EDMA_FILTER_PARAM(0, 3) },
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{ "davinci-mcasp.2", "rx", EDMA_FILTER_PARAM(0, 4) },
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{ "davinci-mcasp.2", "tx", EDMA_FILTER_PARAM(0, 5) },
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{ "spi_davinci.0", "rx", EDMA_FILTER_PARAM(0, 14) },
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{ "spi_davinci.0", "tx", EDMA_FILTER_PARAM(0, 15) },
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{ "da830-mmc.0", "rx", EDMA_FILTER_PARAM(0, 16) },
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{ "da830-mmc.0", "tx", EDMA_FILTER_PARAM(0, 17) },
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{ "spi_davinci.1", "rx", EDMA_FILTER_PARAM(0, 18) },
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{ "spi_davinci.1", "tx", EDMA_FILTER_PARAM(0, 19) },
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};
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This information is going to be needed by the dmaengine driver, so
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modification to the platform_data is needed, and the driver map should be
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added to the pdata of the DMA driver:
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da8xx_edma0_pdata.slave_map = da830_edma_map;
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da8xx_edma0_pdata.slavecnt = ARRAY_SIZE(da830_edma_map);
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The DMA driver then needs to configure the needed device -> filter_fn
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mapping before it registers with dma_async_device_register() :
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ecc->dma_slave.filter_map.map = info->slave_map;
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ecc->dma_slave.filter_map.mapcnt = info->slavecnt;
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ecc->dma_slave.filter_map.fn = edma_filter_fn;
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When neither DT or ACPI lookup is available the dma_request_chan() will
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try to match the requester's device name with the filter_map's list of
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device names, when a match found it will use the information from the
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dma_slave_map to get the channel with the dma_get_channel() internal
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function.
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Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
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Reviewed-by: Arnd Bergmann <arnd@arndb.de>
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Signed-off-by: Vinod Koul <vinod.koul@intel.com>
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---
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Documentation/dmaengine/client.txt | 23 +++-------
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drivers/dma/dmaengine.c | 89 +++++++++++++++++++++++++++++++++-----
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include/linux/dmaengine.h | 51 +++++++++++++++++++---
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3 files changed, 127 insertions(+), 36 deletions(-)
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--- a/Documentation/dmaengine/client.txt
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+++ b/Documentation/dmaengine/client.txt
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@@ -22,25 +22,14 @@ The slave DMA usage consists of followin
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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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-
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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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-
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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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--- a/drivers/dma/dmaengine.c
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+++ b/drivers/dma/dmaengine.c
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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(c
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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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+
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+ if (!device->filter.mapcnt)
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+ return NULL;
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+
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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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+
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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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+
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+ return NULL;
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+}
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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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+
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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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+
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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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+
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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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+
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+ if (!map)
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+ continue;
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+
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+ dma_cap_zero(mask);
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+ dma_cap_set(DMA_SLAVE, mask);
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- return ERR_PTR(-ENODEV);
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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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+
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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_chan
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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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-
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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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+
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+ if (!mask)
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+ return ERR_PTR(-ENODEV);
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+
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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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+
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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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+
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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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--- a/include/linux/dmaengine.h
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+++ b/include/linux/dmaengine.h
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@@ -607,11 +607,38 @@ enum dmaengine_alignment {
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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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+/**
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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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+/**
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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(st
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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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+
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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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+
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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_req
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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(str
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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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+
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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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