From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 914DEC433FE for ; Tue, 8 Feb 2022 22:54:12 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A935A10E27A; Tue, 8 Feb 2022 22:54:07 +0000 (UTC) Received: from mga14.intel.com (mga14.intel.com [192.55.52.115]) by gabe.freedesktop.org (Postfix) with ESMTPS id 3920E10E1E6; Tue, 8 Feb 2022 22:54:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1644360846; x=1675896846; h=date:from:to:subject:message-id:references:mime-version: content-transfer-encoding:in-reply-to; bh=aPL35BSNappDsCRv+IIKJajTLjOCNHovIoDVmKD82rE=; b=WA+0DILJXbzSLu9tsPVvuQT6hEHTejXmZrNWUP2WHaoFA6c3KwyvX+Kj dtLyEpNh1LS9O8DhUIdfo6Me456u2dPZF5FR761tr42Rv5joxtvs1bGDm x28ESV8A+0hRowy79vrINM4cMvWcmny47Y6HqZtiDktWnGhOalGSGCl9g +trujhPhHnuDTk/K2BPDiVztqGld7DnXu9lzKH3aFEdAmNBOU9Mko99VD QOWQ7HxenRPxPVYhihDI+uHIYgMaHMJaaX6zRkIV2Ne/f+0fb/MUa0c4k WV8S+5Aa6y1N7wry+21FlA6MAleUD+vMt31EvR0dPaOrkjlbwGcdfDP7D Q==; X-IronPort-AV: E=McAfee;i="6200,9189,10252"; a="249277028" X-IronPort-AV: E=Sophos;i="5.88,354,1635231600"; d="scan'208";a="249277028" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Feb 2022 14:54:05 -0800 X-IronPort-AV: E=Sophos;i="5.88,354,1635231600"; d="scan'208";a="601401972" Received: from mduanebx-mobl1.amr.corp.intel.com (HELO msatwood-mobl) ([10.212.243.149]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Feb 2022 14:54:05 -0800 Date: Tue, 8 Feb 2022 14:53:41 -0800 From: Matt Atwood To: Lucas De Marchi ;, intel-gfx@lists.freedesktop.org;, dri-devel@lists.freedesktop.org Subject: Re: [Intel-gfx] [PATCH v2 02/18] iosys-map: Add a few more helpers Message-ID: <20220208225341.GA11859@msatwood-mobl> References: <20220208104524.2516209-1-lucas.demarchi@intel.com> <20220208104524.2516209-3-lucas.demarchi@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20220208104524.2516209-3-lucas.demarchi@intel.com> X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Tue, Feb 08, 2022 at 02:45:08AM -0800, Lucas De Marchi wrote: > First the simplest ones: > > - iosys_map_memset(): when abstracting system and I/O memory, > just like the memcpy() use case, memset() also has dedicated > functions to be called for using IO memory. > - iosys_map_memcpy_from(): we may need to copy data from I/O > memory, not only to. > > In certain situations it's useful to be able to read or write to an > offset that is calculated by having the memory layout given by a struct > declaration. Usually we are going to read/write a u8, u16, u32 or u64. > > As a pre-requisite for the implementation, add iosys_map_memcpy_from() > to be the equivalent of iosys_map_memcpy_to(), but in the other > direction. Then add 2 pairs of macros: > > - iosys_map_rd() / iosys_map_wr() > - iosys_map_rd_field() / iosys_map_wr_field() > > The first pair takes the C-type and offset to read/write. The second > pair uses a struct describing the layout of the mapping in order to > calculate the offset and size being read/written. > > We could use readb, readw, readl, readq and the write* counterparts, > however due to alignment issues this may not work on all architectures. > If alignment needs to be checked to call the right function, it's not > possible to decide at compile-time which function to call: so just leave > the decision to the memcpy function that will do exactly that. > > Finally, in order to use the above macros with a map derived from > another, add another initializer: IOSYS_MAP_INIT_OFFSET(). > > v2: > - Rework IOSYS_MAP_INIT_OFFSET() so it doesn't rely on aliasing rules > within the union > - Add offset to both iosys_map_rd_field() and iosys_map_wr_field() to > allow the struct itself to be at an offset from the mapping > - Add documentation to iosys_map_rd_field() with example and expected > memory layout > > Cc: Sumit Semwal > Cc: Christian König > Cc: Thomas Zimmermann > Cc: Mauro Carvalho Chehab > Cc: dri-devel@lists.freedesktop.org > Cc: linux-kernel@vger.kernel.org Reviewed-by: Matt Atwood > Signed-off-by: Lucas De Marchi > --- > include/linux/iosys-map.h | 202 ++++++++++++++++++++++++++++++++++++++ > 1 file changed, 202 insertions(+) > > diff --git a/include/linux/iosys-map.h b/include/linux/iosys-map.h > index edd730b1e899..c6b223534b21 100644 > --- a/include/linux/iosys-map.h > +++ b/include/linux/iosys-map.h > @@ -6,6 +6,7 @@ > #ifndef __IOSYS_MAP_H__ > #define __IOSYS_MAP_H__ > > +#include > #include > #include > > @@ -120,6 +121,45 @@ struct iosys_map { > .is_iomem = false, \ > } > > +/** > + * IOSYS_MAP_INIT_OFFSET - Initializes struct iosys_map from another iosys_map > + * @map_: The dma-buf mapping structure to copy from > + * @offset_: Offset to add to the other mapping > + * > + * Initializes a new iosys_map struct based on another passed as argument. It > + * does a shallow copy of the struct so it's possible to update the back storage > + * without changing where the original map points to. It is the equivalent of > + * doing: > + * > + * .. code-block:: c > + * > + * iosys_map map = other_map; > + * iosys_map_incr(&map, &offset); > + * > + * Example usage: > + * > + * .. code-block:: c > + * > + * void foo(struct device *dev, struct iosys_map *base_map) > + * { > + * ... > + * struct iosys_map map = IOSYS_MAP_INIT_OFFSET(base_map, FIELD_OFFSET); > + * ... > + * } > + * > + * The advantage of using the initializer over just increasing the offset with > + * iosys_map_incr() like above is that the new map will always point to the > + * right place of the buffer during its scope. It reduces the risk of updating > + * the wrong part of the buffer and having no compiler warning about that. If > + * the assignment to IOSYS_MAP_INIT_OFFSET() is forgotten, the compiler can warn > + * about the use of uninitialized variable. > + */ > +#define IOSYS_MAP_INIT_OFFSET(map_, offset_) ({ \ > + struct iosys_map copy = *map_; \ > + iosys_map_incr(©, offset_); \ > + copy; \ > +}) > + > /** > * iosys_map_set_vaddr - Sets a iosys mapping structure to an address in system memory > * @map: The iosys_map structure > @@ -239,6 +279,26 @@ static inline void iosys_map_memcpy_to(struct iosys_map *dst, size_t dst_offset, > memcpy(dst->vaddr + dst_offset, src, len); > } > > +/** > + * iosys_map_memcpy_from - Memcpy from iosys_map into system memory > + * @dst: Destination in system memory > + * @src: The iosys_map structure > + * @src_offset: The offset from which to copy > + * @len: The number of byte in src > + * > + * Copies data from a iosys_map with an offset. The dest buffer is in > + * system memory. Depending on the mapping location, the helper picks the > + * correct method of accessing the memory. > + */ > +static inline void iosys_map_memcpy_from(void *dst, const struct iosys_map *src, > + size_t src_offset, size_t len) > +{ > + if (src->is_iomem) > + memcpy_fromio(dst, src->vaddr_iomem + src_offset, len); > + else > + memcpy(dst, src->vaddr + src_offset, len); > +} > + > /** > * iosys_map_incr - Increments the address stored in a iosys mapping > * @map: The iosys_map structure > @@ -255,4 +315,146 @@ static inline void iosys_map_incr(struct iosys_map *map, size_t incr) > map->vaddr += incr; > } > > +/** > + * iosys_map_memset - Memset iosys_map > + * @dst: The iosys_map structure > + * @offset: Offset from dst where to start setting value > + * @value: The value to set > + * @len: The number of bytes to set in dst > + * > + * Set value in iosys_map. Depending on the buffer's location, the helper > + * picks the correct method of accessing the memory. > + */ > +static inline void iosys_map_memset(struct iosys_map *dst, size_t offset, > + int value, size_t len) > +{ > + if (dst->is_iomem) > + memset_io(dst->vaddr_iomem + offset, value, len); > + else > + memset(dst->vaddr + offset, value, len); > +} > + > +/** > + * iosys_map_rd - Read a C-type value from the iosys_map > + * > + * @map__: The iosys_map structure > + * @offset__: The offset from which to read > + * @type__: Type of the value being read > + * > + * Read a C type value from iosys_map, handling possible un-aligned accesses to > + * the mapping. > + * > + * Returns: > + * The value read from the mapping. > + */ > +#define iosys_map_rd(map__, offset__, type__) ({ \ > + type__ val; \ > + iosys_map_memcpy_from(&val, map__, offset__, sizeof(val)); \ > + val; \ > +}) > + > +/** > + * iosys_map_wr - Write a C-type value to the iosys_map > + * > + * @map__: The iosys_map structure > + * @offset__: The offset from the mapping to write to > + * @type__: Type of the value being written > + * @val__: Value to write > + * > + * Write a C-type value to the iosys_map, handling possible un-aligned accesses > + * to the mapping. > + */ > +#define iosys_map_wr(map__, offset__, type__, val__) ({ \ > + type__ val = (val__); \ > + iosys_map_memcpy_to(map__, offset__, &val, sizeof(val)); \ > +}) > + > +/** > + * iosys_map_rd_field - Read a member from a struct in the iosys_map > + * > + * @map__: The iosys_map structure > + * @struct_offset__: Offset from the beggining of the map, where the struct > + * is located > + * @struct_type__: The struct describing the layout of the mapping > + * @field__: Member of the struct to read > + * > + * Read a value from iosys_map considering its layout is described by a C struct > + * starting at @struct_offset__. The field offset and size is calculated and its > + * value read handling possible un-aligned memory accesses. For example: suppose > + * there is a @struct foo defined as below and the value ``foo.field2.inner2`` > + * needs to be read from the iosys_map: > + * > + * .. code-block:: c > + * > + * struct foo { > + * int field1; > + * struct { > + * int inner1; > + * int inner2; > + * } field2; > + * int field3; > + * } __packed; > + * > + * This is the expected memory layout of a buffer using iosys_map_rd_field(): > + * > + * +------------------------------+--------------------------+ > + * | Address | Content | > + * +==============================+==========================+ > + * | buffer + 0000 | start of mmapped buffer | > + * | | pointed by iosys_map | > + * +------------------------------+--------------------------+ > + * | ... | ... | > + * +------------------------------+--------------------------+ > + * | buffer + ``struct_offset__`` | start of ``struct foo`` | > + * +------------------------------+--------------------------+ > + * | ... | ... | > + * +------------------------------+--------------------------+ > + * | buffer + wwww | ``foo.field2.inner2`` | > + * +------------------------------+--------------------------+ > + * | ... | ... | > + * +------------------------------+--------------------------+ > + * | buffer + yyyy | end of ``struct foo`` | > + * +------------------------------+--------------------------+ > + * | ... | ... | > + * +------------------------------+--------------------------+ > + * | buffer + zzzz | end of mmaped buffer | > + * +------------------------------+--------------------------+ > + * > + * Values automatically calculated by this macro or not needed are denoted by > + * wwww, yyyy and zzzz. This is the code to read that value: > + * > + * .. code-block:: c > + * > + * x = iosys_map_rd_field(&map, offset, struct foo, field2.inner2); > + * > + * Returns: > + * The value read from the mapping. > + */ > +#define iosys_map_rd_field(map__, struct_offset__, struct_type__, field__) ({ \ > + struct_type__ *s; \ > + iosys_map_rd(map__, struct_offset__ + offsetof(struct_type__, field__), \ > + typeof(s->field__)); \ > +}) > + > +/** > + * iosys_map_wr_field - Write to a member of a struct in the iosys_map > + * > + * @map__: The iosys_map structure > + * @struct_offset__: Offset from the beggining of the map, where the struct > + * is located > + * @struct_type__: The struct describing the layout of the mapping > + * @field__: Member of the struct to read > + * @val__: Value to write > + * > + * Write a value to the iosys_map considering its layout is described by a C struct > + * starting at @struct_offset__. The field offset and size is calculated and the > + * @val__ is written handling possible un-aligned memory accesses. Refer to > + * iosys_map_rd_field() for expected usage and memory layout. > + */ > +#define iosys_map_wr_field(map__, struct_offset__, struct_type__, field__, val__) ({ \ > + struct_type__ *s; \ > + iosys_map_wr(map__, struct_offset__ + offsetof(struct_type__, field__), \ > + typeof(s->field__), val__); \ > +}) > + > #endif /* __IOSYS_MAP_H__ */ > -- > 2.35.1 >