From: Thomas Zimmermann <tzimmermann@suse.de>
To: maarten.lankhorst@linux.intel.com, mripard@kernel.org,
airlied@linux.ie, daniel@ffwll.ch, sam@ravnborg.org,
alexander.deucher@amd.com, christian.koenig@amd.com,
kraxel@redhat.com, l.stach@pengutronix.de,
linux+etnaviv@armlinux.org.uk, christian.gmeiner@gmail.com,
inki.dae@samsung.com, jy0922.shim@samsung.com,
sw0312.kim@samsung.com, kyungmin.park@samsung.com,
kgene@kernel.org, krzk@kernel.org, yuq825@gmail.com,
bskeggs@redhat.com, robh@kernel.org, tomeu.vizoso@collabora.com,
steven.price@arm.com, alyssa.rosenzweig@collabora.com,
hjc@rock-chips.com, heiko@sntech.de, hdegoede@redhat.com,
sean@poorly.run, eric@anholt.net,
oleksandr_andrushchenko@epam.com, ray.huang@amd.com,
sumit.semwal@linaro.org, emil.velikov@collabora.com,
luben.tuikov@amd.com, apaneers@amd.com, linus.walleij@linaro.org,
melissa.srw@gmail.com, chris@chris-wilson.co.uk,
miaoqinglang@huawei.com
Cc: linux-samsung-soc@vger.kernel.org, lima@lists.freedesktop.org,
nouveau@lists.freedesktop.org, etnaviv@lists.freedesktop.org,
amd-gfx@lists.freedesktop.org,
virtualization@lists.linux-foundation.org,
linaro-mm-sig@lists.linaro.org,
linux-rockchip@lists.infradead.org,
dri-devel@lists.freedesktop.org,
Thomas Zimmermann <tzimmermann@suse.de>,
xen-devel@lists.xenproject.org,
spice-devel@lists.freedesktop.org,
linux-arm-kernel@lists.infradead.org,
linux-media@vger.kernel.org
Subject: [PATCH v6 09/10] dma-buf-map: Add memcpy and pointer-increment interfaces
Date: Wed, 28 Oct 2020 20:35:20 +0100 [thread overview]
Message-ID: <20201028193521.2489-10-tzimmermann@suse.de> (raw)
In-Reply-To: <20201028193521.2489-1-tzimmermann@suse.de>
To do framebuffer updates, one needs memcpy from system memory and a
pointer-increment function. Add both interfaces with documentation.
v5:
* include <linux/string.h> to build on sparc64 (Sam)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Tested-by: Sam Ravnborg <sam@ravnborg.org>
---
include/linux/dma-buf-map.h | 73 ++++++++++++++++++++++++++++++++-----
1 file changed, 63 insertions(+), 10 deletions(-)
diff --git a/include/linux/dma-buf-map.h b/include/linux/dma-buf-map.h
index 2e8bbecb5091..583a3a1f9447 100644
--- a/include/linux/dma-buf-map.h
+++ b/include/linux/dma-buf-map.h
@@ -7,6 +7,7 @@
#define __DMA_BUF_MAP_H__
#include <linux/io.h>
+#include <linux/string.h>
/**
* DOC: overview
@@ -32,6 +33,14 @@
* accessing the buffer. Use the returned instance and the helper functions
* to access the buffer's memory in the correct way.
*
+ * The type :c:type:`struct dma_buf_map <dma_buf_map>` and its helpers are
+ * actually independent from the dma-buf infrastructure. When sharing buffers
+ * among devices, drivers have to know the location of the memory to access
+ * the buffers in a safe way. :c:type:`struct dma_buf_map <dma_buf_map>`
+ * solves this problem for dma-buf and its users. If other drivers or
+ * sub-systems require similar functionality, the type could be generalized
+ * and moved to a more prominent header file.
+ *
* Open-coding access to :c:type:`struct dma_buf_map <dma_buf_map>` is
* considered bad style. Rather then accessing its fields directly, use one
* of the provided helper functions, or implement your own. For example,
@@ -51,6 +60,14 @@
*
* dma_buf_map_set_vaddr_iomem(&map. 0xdeadbeaf);
*
+ * Instances of struct dma_buf_map do not have to be cleaned up, but
+ * can be cleared to NULL with dma_buf_map_clear(). Cleared mappings
+ * always refer to system memory.
+ *
+ * .. code-block:: c
+ *
+ * dma_buf_map_clear(&map);
+ *
* Test if a mapping is valid with either dma_buf_map_is_set() or
* dma_buf_map_is_null().
*
@@ -73,17 +90,19 @@
* if (dma_buf_map_is_equal(&sys_map, &io_map))
* // always false
*
- * Instances of struct dma_buf_map do not have to be cleaned up, but
- * can be cleared to NULL with dma_buf_map_clear(). Cleared mappings
- * always refer to system memory.
+ * A set up instance of struct dma_buf_map can be used to access or manipulate
+ * the buffer memory. Depending on the location of the memory, the provided
+ * helpers will pick the correct operations. Data can be copied into the memory
+ * with dma_buf_map_memcpy_to(). The address can be manipulated with
+ * dma_buf_map_incr().
*
- * The type :c:type:`struct dma_buf_map <dma_buf_map>` and its helpers are
- * actually independent from the dma-buf infrastructure. When sharing buffers
- * among devices, drivers have to know the location of the memory to access
- * the buffers in a safe way. :c:type:`struct dma_buf_map <dma_buf_map>`
- * solves this problem for dma-buf and its users. If other drivers or
- * sub-systems require similar functionality, the type could be generalized
- * and moved to a more prominent header file.
+ * .. code-block:: c
+ *
+ * const void *src = ...; // source buffer
+ * size_t len = ...; // length of src
+ *
+ * dma_buf_map_memcpy_to(&map, src, len);
+ * dma_buf_map_incr(&map, len); // go to first byte after the memcpy
*/
/**
@@ -210,4 +229,38 @@ static inline void dma_buf_map_clear(struct dma_buf_map *map)
}
}
+/**
+ * dma_buf_map_memcpy_to - Memcpy into dma-buf mapping
+ * @dst: The dma-buf mapping structure
+ * @src: The source buffer
+ * @len: The number of byte in src
+ *
+ * Copies data into a dma-buf mapping. The source buffer is in system
+ * memory. Depending on the buffer's location, the helper picks the correct
+ * method of accessing the memory.
+ */
+static inline void dma_buf_map_memcpy_to(struct dma_buf_map *dst, const void *src, size_t len)
+{
+ if (dst->is_iomem)
+ memcpy_toio(dst->vaddr_iomem, src, len);
+ else
+ memcpy(dst->vaddr, src, len);
+}
+
+/**
+ * dma_buf_map_incr - Increments the address stored in a dma-buf mapping
+ * @map: The dma-buf mapping structure
+ * @incr: The number of bytes to increment
+ *
+ * Increments the address stored in a dma-buf mapping. Depending on the
+ * buffer's location, the correct value will be updated.
+ */
+static inline void dma_buf_map_incr(struct dma_buf_map *map, size_t incr)
+{
+ if (map->is_iomem)
+ map->vaddr_iomem += incr;
+ else
+ map->vaddr += incr;
+}
+
#endif /* __DMA_BUF_MAP_H__ */
--
2.29.0
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next prev parent reply other threads:[~2020-10-28 19:36 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-28 19:35 [PATCH v6 00/10] Support GEM object mappings from I/O memory Thomas Zimmermann
2020-10-28 19:35 ` [PATCH v6 01/10] drm/vram-helper: Remove invariant parameters from internal kmap function Thomas Zimmermann
2020-10-28 19:35 ` [PATCH v6 02/10] drm/cma-helper: Remove empty drm_gem_cma_prime_vunmap() Thomas Zimmermann
2020-10-28 19:35 ` [PATCH v6 03/10] drm/etnaviv: Remove empty etnaviv_gem_prime_vunmap() Thomas Zimmermann
2020-10-28 19:35 ` [PATCH v6 04/10] drm/exynos: Remove empty exynos_drm_gem_prime_{vmap, vunmap}() Thomas Zimmermann
2020-10-28 19:35 ` [PATCH v6 05/10] drm/ttm: Add vmap/vunmap to TTM and TTM GEM helpers Thomas Zimmermann
2020-10-28 19:35 ` [PATCH v6 06/10] drm/gem: Use struct dma_buf_map in GEM vmap ops and convert GEM backends Thomas Zimmermann
2020-10-28 19:35 ` [PATCH v6 07/10] drm/gem: Update internal GEM vmap/vunmap interfaces to use struct dma_buf_map Thomas Zimmermann
2020-10-28 19:35 ` [PATCH v6 08/10] drm/gem: Store client buffer mappings as " Thomas Zimmermann
2020-10-28 19:35 ` Thomas Zimmermann [this message]
2020-10-28 19:35 ` [PATCH v6 10/10] drm/fb_helper: Support framebuffers in I/O memory Thomas Zimmermann
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