| Message ID | 1449153192-9082-4-git-send-email-peter.ujfalusi@ti.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thursday 03 December 2015 16:33:11 Peter Ujfalusi wrote: > + > +/** > + * 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_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) > + chan = of_dma_request_slave_channel(dev->of_node, name); > + > + /* If device was enumerated by ACPI get slave info from here */ > + if (has_acpi_companion(dev) && !chan) > + chan = acpi_dma_request_slave_chan_by_name(dev, name); I just noticed that you are creating this as a new interface, rather than changing dma_request_slave_channel_reason() and making the old interface a static inline wrapper. What is the reasoning behind that? I think if we make both interfaces do the same thing, it's easier to do the migration. > + if (chan) { > + /* Valid channel found */ > + if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER) > + return chan; > + > + pr_warn("%s: %s DMA request failed, falling back to legacy\n", > + __func__, dev->of_node ? "OF" : "ACPI"); > + } Maybe print the error code as well? Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On 12/03/2015 05:32 PM, Arnd Bergmann wrote: > On Thursday 03 December 2015 16:33:11 Peter Ujfalusi wrote: >> + >> +/** >> + * 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_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) >> + chan = of_dma_request_slave_channel(dev->of_node, name); >> + >> + /* If device was enumerated by ACPI get slave info from here */ >> + if (has_acpi_companion(dev) && !chan) >> + chan = acpi_dma_request_slave_chan_by_name(dev, name); > > I just noticed that you are creating this as a new interface, rather than > changing dma_request_slave_channel_reason() and making the old interface > a static inline wrapper. What is the reasoning behind that? Oh, it was in my plans. Will do it for v02 > I think if we make both interfaces do the same thing, it's easier > to do the migration. > >> + if (chan) { >> + /* Valid channel found */ >> + if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER) >> + return chan; >> + >> + pr_warn("%s: %s DMA request failed, falling back to legacy\n", >> + __func__, dev->of_node ? "OF" : "ACPI"); >> + } > > Maybe print the error code as well? Or remove the print altogether? In a healthy system we will either get the channel or the EPROBE_DEFER, in case of the platforms where the DT lookup does not work we expect errors and it is 'normal'. I think if we fail via DT/ACPI and we fail with legacy also then the client driver will say something about it anyways, or deal with it as it see fits.
On Thursday 03 December 2015 17:42:31 Peter Ujfalusi wrote: > > > >> + if (chan) { > >> + /* Valid channel found */ > >> + if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER) > >> + return chan; > >> + > >> + pr_warn("%s: %s DMA request failed, falling back to legacy\n", > >> + __func__, dev->of_node ? "OF" : "ACPI"); > >> + } > > > > Maybe print the error code as well? > > Or remove the print altogether? > In a healthy system we will either get the channel or the EPROBE_DEFER, in > case of the platforms where the DT lookup does not work we expect errors and > it is 'normal'. > I think if we fail via DT/ACPI and we fail with legacy also then the client > driver will say something about it anyways, or deal with it as it see fits. > Right, that works too. It took me a while to figure out that we only get there on systems that have ACPI or DT enabled for a particular device, but where the normal method failed, rather than also systems with traditional board files. Without the pr_warn, I would not have needed to think about this ;-) Arnd -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Thu, Dec 3, 2015 at 4:33 PM, Peter Ujfalusi <peter.ujfalusi@ti.com> wrote: > 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() : > > if (info->slave_map) { > ecc->dma_slave.filter_map.map = info->slave_map; > ecc->dma_slave.filter_map.mapcnt = info->slavecnt; > ecc->dma_slave.filter_map.filter_fn = edma_filter_fn; One nitpick here. I think filter_map.filter_fn naming is duplicate. What about dma_device .filter -> filter data (or .filter_data) .map -> mappings .map_count -> # of entries in mappings .fn -> filter function What do you think? > } > > 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.
diff --git a/Documentation/dmaengine/client.txt b/Documentation/dmaengine/client.txt index d9f9f461102a..9e33189745f0 100644 --- a/Documentation/dmaengine/client.txt +++ b/Documentation/dmaengine/client.txt @@ -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. diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c index ea9d66982d40..fee4912d64d6 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> @@ -712,6 +713,99 @@ struct dma_chan *dma_request_slave_channel(struct device *dev, } EXPORT_SYMBOL_GPL(dma_request_slave_channel); +const static struct dma_slave_map *dma_filter_match(struct dma_device *device, + const char *name, + struct device *dev) +{ + int i; + + if (!device->filter_map.mapcnt) + return NULL; + + for (i = 0; i < device->filter_map.mapcnt; i++) { + const struct dma_slave_map *map = &device->filter_map.map[i]; + + if (!strcmp(map->devname, dev_name(dev)) && + !strcmp(map->slave, name)) + return map; + } + + return NULL; +} + +/** + * 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_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) + chan = of_dma_request_slave_channel(dev->of_node, name); + + /* If device was enumerated by ACPI get slave info from here */ + if (has_acpi_companion(dev) && !chan) + chan = acpi_dma_request_slave_chan_by_name(dev, name); + + if (chan) { + /* Valid channel found */ + if (!IS_ERR(chan) || PTR_ERR(chan) == -EPROBE_DEFER) + return chan; + + pr_warn("%s: %s DMA request failed, falling back to legacy\n", + __func__, dev->of_node ? "OF" : "ACPI"); + } + + /* 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_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); + +/** + * 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); diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h index a2b7c2071cf4..1c3997461ae7 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -607,11 +607,38 @@ enum dmaengine_alignment { }; /** + * 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.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 + * @filter_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 filter_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_map: 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 @@ -669,6 +696,7 @@ 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 +1263,10 @@ 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 +1300,16 @@ 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, + 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) { }
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() : if (info->slave_map) { ecc->dma_slave.filter_map.map = info->slave_map; ecc->dma_slave.filter_map.mapcnt = info->slavecnt; ecc->dma_slave.filter_map.filter_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> --- Documentation/dmaengine/client.txt | 23 +++------- drivers/dma/dmaengine.c | 94 ++++++++++++++++++++++++++++++++++++++ include/linux/dmaengine.h | 42 +++++++++++++++++ 3 files changed, 142 insertions(+), 17 deletions(-)