Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758642AbbLBOGZ (ORCPT ); Wed, 2 Dec 2015 09:06:25 -0500 Received: from bear.ext.ti.com ([192.94.94.41]:50324 "EHLO bear.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758347AbbLBOAN (ORCPT ); Wed, 2 Dec 2015 09:00:13 -0500 From: Peter Ujfalusi To: , , CC: , , , , , , , Subject: [RFC v03 03/15] dmaengine: core: Introduce new, universal API to request a channel Date: Wed, 2 Dec 2015 15:59:13 +0200 Message-ID: <1449064765-27427-4-git-send-email-peter.ujfalusi@ti.com> X-Mailer: git-send-email 2.6.3 In-Reply-To: <1449064765-27427-1-git-send-email-peter.ujfalusi@ti.com> References: <1449064765-27427-1-git-send-email-peter.ujfalusi@ti.com> MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 9918 Lines: 284 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_filter_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_filter_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_filter_map to get the channel with the dma_get_channel() internal function. Signed-off-by: Peter Ujfalusi --- Documentation/dmaengine/client.txt | 23 +++------ drivers/dma/dmaengine.c | 98 ++++++++++++++++++++++++++++++++++++++ include/linux/dmaengine.h | 27 +++++++++++ 3 files changed, 131 insertions(+), 17 deletions(-) diff --git a/Documentation/dmaengine/client.txt b/Documentation/dmaengine/client.txt index d9f9f461102a..6c72a06eb1a5 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_map_filter 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..b9dc1512c4aa 100644 --- a/drivers/dma/dmaengine.c +++ b/drivers/dma/dmaengine.c @@ -43,6 +43,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include #include #include #include @@ -712,6 +713,103 @@ struct dma_chan *dma_request_slave_channel(struct device *dev, } EXPORT_SYMBOL_GPL(dma_request_slave_channel); +const static struct dma_filter_map *dma_filter_match(struct dma_device *device, + const char *name, + struct device *dev) +{ + const struct dma_filter_map *map_found = NULL; + int i; + + if (!device->filter_map.mapcnt) + return NULL; + + for (i = 0; i < device->filter_map.mapcnt; i++) { + const struct dma_filter_map *map = &device->filter_map.map[i]; + + if (!strcmp(map->devname, dev_name(dev)) && + !strcmp(map->slave, name)) { + map_found = map; + break; + } + } + + return map_found; +} + +/** + * 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 *device, *_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)) + 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(device, _d, &dma_device_list, global_node) { + dma_cap_mask_t mask; + const struct dma_filter_map *map = dma_filter_match(device, + name, dev); + + if (!map) + continue; + + dma_cap_zero(mask); + dma_cap_set(DMA_SLAVE, mask); + + chan = find_candidate(device, &mask, + device->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..49d48e69c179 100644 --- a/include/linux/dmaengine.h +++ b/include/linux/dmaengine.h @@ -606,6 +606,18 @@ enum dmaengine_alignment { DMAENGINE_ALIGN_64_BYTES = 6, }; +struct dma_filter_map { + char *devname; + char *slave; + void *param; +}; + +struct dma_filter { + dma_filter_fn filter_fn; + int mapcnt; + const struct dma_filter_map *map; +}; + /** * struct dma_device - info on the entity supplying DMA services * @chancnt: how many DMA channels are supported @@ -669,6 +681,7 @@ 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 +1248,10 @@ 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 +1285,16 @@ 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) { } -- 2.6.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/