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Re: [PATCH V19 09/13] MIPS: Loongson: Add swiotlb to support All-Memory

To: "Aurelien Jarno" <aurelien@aurel32.net>
Subject: Re: [PATCH V19 09/13] MIPS: Loongson: Add swiotlb to support All-Memory DMA
From: "陈华才" <chenhc@lemote.com>
Date: Mon, 17 Feb 2014 13:41:49 +0800
Cc: "Ralf Baechle" <ralf@linux-mips.org>, "John Crispin" <john@phrozen.org>, "Steven J. Hill" <steven.hill@imgtec.com>, linux-mips@linux-mips.org, "Fuxin Zhang" <zhangfx@lemote.com>, "Zhangjin Wu" <wuzhangjin@gmail.com>, "Hongliang Tao" <taohl@lemote.com>, "Hua Yan" <yanh@lemote.com>
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References: <1392537690-5961-1-git-send-email-chenhc@lemote.com> <1392537690-5961-10-git-send-email-chenhc@lemote.com> <20140216211206.GA491@hall.aurel32.net>
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> On Sun, Feb 16, 2014 at 04:01:26PM +0800, Huacai Chen wrote:
>> Loongson doesn't support DMA address above 4GB traditionally. If memory
>> is more than 4GB, CONFIG_SWIOTLB and ZONE_DMA32 should be selected. In
>> this way, DMA pages are allocated below 4GB preferably. However, if low
>> memory is not enough, high pages are allocated and swiotlb is used for
>> bouncing.
>>
>> Moreover, we provide a platform-specific dma_map_ops::set_dma_mask() to
>> set a device's dma_mask and coherent_dma_mask. We use these masks to
>> distinguishes an allocated page can be used for DMA directly, or need
>> swiotlb to bounce.
>>
>> Recently, we found that 32-bit DMA isn't a hardware bug, but a hardware
>> configuration issue. So, latest firmware has enable the DMA support as
>> high as 40-bit. To support all-memory DMA for all devices (besides the
>> Loongson platform limit, there are still some devices have their own
>> DMA32 limit), and also to be compatible with old firmware, we keep use
>> swiotlb.
>>
>> Signed-off-by: Huacai Chen <chenhc@lemote.com>
>> Signed-off-by: Hongliang Tao <taohl@lemote.com>
>> Signed-off-by: Hua Yan <yanh@lemote.com>
>> Tested-by: Alex Smith <alex.smith@imgtec.com>
>> Reviewed-by: Alex Smith <alex.smith@imgtec.com>
>> ---
>>  arch/mips/include/asm/dma-mapping.h                |    5 +
>>  .../mips/include/asm/mach-loongson/dma-coherence.h |   22 +++-
>>  arch/mips/loongson/common/Makefile                 |    5 +
>>  arch/mips/loongson/common/dma-swiotlb.c            |  136
>> ++++++++++++++++++++
>>  4 files changed, 167 insertions(+), 1 deletions(-)
>>  create mode 100644 arch/mips/loongson/common/dma-swiotlb.c
>>
>> diff --git a/arch/mips/include/asm/dma-mapping.h
>> b/arch/mips/include/asm/dma-mapping.h
>> index 84238c5..06412aa 100644
>> --- a/arch/mips/include/asm/dma-mapping.h
>> +++ b/arch/mips/include/asm/dma-mapping.h
>> @@ -49,9 +49,14 @@ static inline int dma_mapping_error(struct device
>> *dev, u64 mask)
>>  static inline int
>>  dma_set_mask(struct device *dev, u64 mask)
>>  {
>> +    struct dma_map_ops *ops = get_dma_ops(dev);
>> +
>>      if(!dev->dma_mask || !dma_supported(dev, mask))
>>              return -EIO;
>>
>> +    if (ops->set_dma_mask)
>> +            return ops->set_dma_mask(dev, mask);
>> +
>>      *dev->dma_mask = mask;
>>
>>      return 0;
>> diff --git a/arch/mips/include/asm/mach-loongson/dma-coherence.h
>> b/arch/mips/include/asm/mach-loongson/dma-coherence.h
>> index aeb2c05..6a90275 100644
>> --- a/arch/mips/include/asm/mach-loongson/dma-coherence.h
>> +++ b/arch/mips/include/asm/mach-loongson/dma-coherence.h
>> @@ -11,24 +11,40 @@
>>  #ifndef __ASM_MACH_LOONGSON_DMA_COHERENCE_H
>>  #define __ASM_MACH_LOONGSON_DMA_COHERENCE_H
>>
>> +#ifdef CONFIG_SWIOTLB
>> +#include <linux/swiotlb.h>
>> +#endif
>> +
>>  struct device;
>>
>> +extern dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr);
>> +extern phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr);
>>  static inline dma_addr_t plat_map_dma_mem(struct device *dev, void
>> *addr,
>>                                        size_t size)
>>  {
>> +#ifdef CONFIG_CPU_LOONGSON3
>> +    return virt_to_phys(addr);
>> +#else
>>      return virt_to_phys(addr) | 0x80000000;
>> +#endif
>>  }
>>
>>  static inline dma_addr_t plat_map_dma_mem_page(struct device *dev,
>>                                             struct page *page)
>>  {
>> +#ifdef CONFIG_CPU_LOONGSON3
>> +    return page_to_phys(page);
>> +#else
>>      return page_to_phys(page) | 0x80000000;
>> +#endif
>>  }
>>
>>  static inline unsigned long plat_dma_addr_to_phys(struct device *dev,
>>      dma_addr_t dma_addr)
>>  {
>> -#if defined(CONFIG_CPU_LOONGSON2F) && defined(CONFIG_64BIT)
>> +#if defined(CONFIG_CPU_LOONGSON3) && defined(CONFIG_64BIT)
>> +    return dma_addr;
>> +#elif defined(CONFIG_CPU_LOONGSON2F) && defined(CONFIG_64BIT)
>>      return (dma_addr > 0x8fffffff) ? dma_addr : (dma_addr & 0x0fffffff);
>>  #else
>>      return dma_addr & 0x7fffffff;
>> @@ -55,7 +71,11 @@ static inline int plat_dma_supported(struct device
>> *dev, u64 mask)
>>
>>  static inline int plat_device_is_coherent(struct device *dev)
>>  {
>> +#ifdef CONFIG_DMA_NONCOHERENT
>>      return 0;
>> +#else
>> +    return 1;
>> +#endif /* CONFIG_DMA_NONCOHERENT */
>>  }
>>
>>  #endif /* __ASM_MACH_LOONGSON_DMA_COHERENCE_H */
>> diff --git a/arch/mips/loongson/common/Makefile
>> b/arch/mips/loongson/common/Makefile
>> index 9e4484c..0bb9cc9 100644
>> --- a/arch/mips/loongson/common/Makefile
>> +++ b/arch/mips/loongson/common/Makefile
>> @@ -26,3 +26,8 @@ obj-$(CONFIG_CS5536) += cs5536/
>>  #
>>
>>  obj-$(CONFIG_LOONGSON_SUSPEND) += pm.o
>> +
>> +#
>> +# Big Memory (SWIOTLB) Support
>> +#
>> +obj-$(CONFIG_SWIOTLB) += dma-swiotlb.o
>> diff --git a/arch/mips/loongson/common/dma-swiotlb.c
>> b/arch/mips/loongson/common/dma-swiotlb.c
>> new file mode 100644
>> index 0000000..c2be01f
>> --- /dev/null
>> +++ b/arch/mips/loongson/common/dma-swiotlb.c
>> @@ -0,0 +1,136 @@
>> +#include <linux/mm.h>
>> +#include <linux/init.h>
>> +#include <linux/dma-mapping.h>
>> +#include <linux/scatterlist.h>
>> +#include <linux/swiotlb.h>
>> +#include <linux/bootmem.h>
>> +
>> +#include <asm/bootinfo.h>
>> +#include <boot_param.h>
>> +#include <dma-coherence.h>
>> +
>> +static void *loongson_dma_alloc_coherent(struct device *dev, size_t
>> size,
>> +            dma_addr_t *dma_handle, gfp_t gfp, struct dma_attrs *attrs)
>> +{
>> +    void *ret;
>> +
>> +    if (dma_alloc_from_coherent(dev, size, dma_handle, &ret))
>> +            return ret;
>> +
>> +    /* ignore region specifiers */
>> +    gfp &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM);
>> +
>> +#ifdef CONFIG_ISA
>> +    if (dev == NULL)
>> +            gfp |= __GFP_DMA;
>> +    else
>> +#endif
>> +#ifdef CONFIG_ZONE_DMA
>> +    if (dev->coherent_dma_mask < DMA_BIT_MASK(32))
>> +            gfp |= __GFP_DMA;
>> +    else
>> +#endif
>> +#ifdef CONFIG_ZONE_DMA32
>> +    if (dev->coherent_dma_mask < DMA_BIT_MASK(40))
>> +            gfp |= __GFP_DMA32;
>> +    else
>
> I think the same logic as in loongson_dma_set_mask should be used there,
> so that the bounce buffer is not used when it is possible to directly
> allocate the memory correctly. Something like this should work:
It seems like that we needn't to do so. Assume that loongson_sysconf.
dma_mask_bits is 41 and a device's dma_mask is 40. DMA32 zone is very
limited, but all physical memory addresses are below 40bit. If using
 __GFP_DMA32, swiotlb is probably needed because DMA32 zone is exhausted
by those dma32 devices; but if not using __GFP_DMA32, swiotlb isn't need
completely.

Huacai

>
> #ifdef CONFIG_ZONE_DMA32
>       if (dev->coherent_dma_mask <
> DMA_BIT_MASK(loongson_sysconf.dma_mask_bits))
>               gfp |= __GFP_DMA32;
>       else
> #endif
>
>> +#endif
>> +    ;
>> +    gfp |= __GFP_NORETRY;
>> +
>> +    ret = swiotlb_alloc_coherent(dev, size, dma_handle, gfp);
>> +    mb();
>> +    return ret;
>> +}
>> +
>> +static void loongson_dma_free_coherent(struct device *dev, size_t size,
>> +            void *vaddr, dma_addr_t dma_handle, struct dma_attrs *attrs)
>> +{
>> +    int order = get_order(size);
>> +
>> +    if (dma_release_from_coherent(dev, order, vaddr))
>> +            return;
>> +
>> +    swiotlb_free_coherent(dev, size, vaddr, dma_handle);
>> +}
>> +
>> +static dma_addr_t loongson_dma_map_page(struct device *dev, struct page
>> *page,
>> +                            unsigned long offset, size_t size,
>> +                            enum dma_data_direction dir,
>> +                            struct dma_attrs *attrs)
>> +{
>> +    dma_addr_t daddr = swiotlb_map_page(dev, page, offset, size,
>> +                                    dir, attrs);
>> +    mb();
>> +    return daddr;
>> +}
>> +
>> +static int loongson_dma_map_sg(struct device *dev, struct scatterlist
>> *sg,
>> +                            int nents, enum dma_data_direction dir,
>> +                            struct dma_attrs *attrs)
>> +{
>> +    int r = swiotlb_map_sg_attrs(dev, sg, nents, dir, NULL);
>> +    mb();
>> +
>> +    return r;
>> +}
>> +
>> +static void loongson_dma_sync_single_for_device(struct device *dev,
>> +                            dma_addr_t dma_handle, size_t size,
>> +                            enum dma_data_direction dir)
>> +{
>> +    swiotlb_sync_single_for_device(dev, dma_handle, size, dir);
>> +    mb();
>> +}
>> +
>> +static void loongson_dma_sync_sg_for_device(struct device *dev,
>> +                            struct scatterlist *sg, int nents,
>> +                            enum dma_data_direction dir)
>> +{
>> +    swiotlb_sync_sg_for_device(dev, sg, nents, dir);
>> +    mb();
>> +}
>> +
>> +static int loongson_dma_set_mask(struct device *dev, u64 mask)
>> +{
>> +    if (mask > DMA_BIT_MASK(loongson_sysconf.dma_mask_bits)) {
>> +            *dev->dma_mask = DMA_BIT_MASK(loongson_sysconf.dma_mask_bits);
>> +            return -EIO;
>> +    }
>> +
>> +    *dev->dma_mask = mask;
>> +
>> +    return 0;
>> +}
>> +
>> +dma_addr_t phys_to_dma(struct device *dev, phys_addr_t paddr)
>> +{
>> +    return paddr;
>> +}
>> +
>> +phys_addr_t dma_to_phys(struct device *dev, dma_addr_t daddr)
>> +{
>> +    return daddr;
>> +}
>> +
>> +static struct dma_map_ops loongson_dma_map_ops = {
>> +    .alloc = loongson_dma_alloc_coherent,
>> +    .free = loongson_dma_free_coherent,
>> +    .map_page = loongson_dma_map_page,
>> +    .unmap_page = swiotlb_unmap_page,
>> +    .map_sg = loongson_dma_map_sg,
>> +    .unmap_sg = swiotlb_unmap_sg_attrs,
>> +    .sync_single_for_cpu = swiotlb_sync_single_for_cpu,
>> +    .sync_single_for_device = loongson_dma_sync_single_for_device,
>> +    .sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
>> +    .sync_sg_for_device = loongson_dma_sync_sg_for_device,
>> +    .mapping_error = swiotlb_dma_mapping_error,
>> +    .dma_supported = swiotlb_dma_supported,
>> +    .set_dma_mask = loongson_dma_set_mask
>> +};
>> +
>> +void __init plat_swiotlb_setup(void)
>> +{
>> +    swiotlb_init(1);
>> +    mips_dma_map_ops = &loongson_dma_map_ops;
>> +}
>> --
>> 1.7.7.3
>>
>>
>
> --
> Aurelien Jarno                                GPG: 1024D/F1BCDB73
> aurelien@aurel32.net                 http://www.aurel32.net
>



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