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Sun, 17 Oct 2021 02:28:50 -0700 (PDT) Subject: Re: [RFC PATCH v2 07/11] riscv: cmo: Add dma-noncoherency support To: guoren@kernel.org, anup.patel@wdc.com, palmerdabbelt@google.com, arnd@arndb.de, wens@csie.org, maxime@cerno.tech, drew@beagleboard.org, liush@allwinnertech.com, lazyparser@gmail.com, wefu@redhat.com Cc: linux-riscv@lists.infradead.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, linux-sunxi@lists.linux.dev, Guo Ren , Christoph Hellwig References: <1622970249-50770-1-git-send-email-guoren@kernel.org> <1622970249-50770-11-git-send-email-guoren@kernel.org> From: twd2 Message-ID: Date: Sun, 17 Oct 2021 17:28:43 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 In-Reply-To: <1622970249-50770-11-git-send-email-guoren@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit On 2021/6/6 17:04, guoren@kernel.org wrote: > From: Guo Ren > > To support DMA device in a non-coherent interconnect SOC system, > we need the below facilities: > - Changing a virtual memory mapping region attributes from > cacheable to noncache + strong order which used in DMA > descriptors. > - Add noncache + weakorder virtual memory attributes for dma > mapping. > - Syncing the cache with memory before DMA start and after DMA > end with vendor custom CMO instructions. > > This patch enables linux kernel generic dma-noncoherency > infrastructure and introduces new sbi_ecall API for dma_sync. > > @@ -27,6 +27,7 @@ enum sbi_ext_id { > + SBI_EXT_DMA = 0xAB150401, > > Signed-off-by: Guo Ren > Signed-off-by: Liu Shaohua > Cc: Palmer Dabbelt > Cc: Christoph Hellwig > Cc: Anup Patel > Cc: Arnd Bergmann > Cc: Drew Fustini > Cc: Wei Fu > Cc: Wei Wu > Cc: Chen-Yu Tsai > Cc: Maxime Ripard > --- > arch/riscv/Kconfig | 5 ++++ > arch/riscv/include/asm/pgtable.h | 26 ++++++++++++++++++++ > arch/riscv/include/asm/sbi.h | 15 ++++++++++++ > arch/riscv/kernel/sbi.c | 19 ++++++++++++++ > arch/riscv/mm/Makefile | 1 + > arch/riscv/mm/dma-mapping.c | 53 ++++++++++++++++++++++++++++++++++++++++ > 6 files changed, 119 insertions(+) > create mode 100644 arch/riscv/mm/dma-mapping.c > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > index 05c4976..817a9bb 100644 > --- a/arch/riscv/Kconfig > +++ b/arch/riscv/Kconfig > @@ -20,6 +20,10 @@ config RISCV > select ARCH_HAS_DEBUG_VM_PGTABLE > select ARCH_HAS_DEBUG_VIRTUAL if MMU > select ARCH_HAS_DEBUG_WX > + select ARCH_HAS_DMA_PREP_COHERENT > + select ARCH_HAS_SYNC_DMA_FOR_CPU > + select ARCH_HAS_SYNC_DMA_FOR_DEVICE > + select ARCH_HAS_DMA_WRITE_COMBINE > select ARCH_HAS_FORTIFY_SOURCE > select ARCH_HAS_GCOV_PROFILE_ALL > select ARCH_HAS_GIGANTIC_PAGE > @@ -43,6 +47,7 @@ config RISCV > select CLONE_BACKWARDS > select CLINT_TIMER if !MMU > select COMMON_CLK > + select DMA_DIRECT_REMAP > select EDAC_SUPPORT > select GENERIC_ARCH_TOPOLOGY if SMP > select GENERIC_ATOMIC64 if !64BIT > diff --git a/arch/riscv/include/asm/pgtable.h b/arch/riscv/include/asm/pgtable.h > index 6ddeb49..e1a82b6 100644 > --- a/arch/riscv/include/asm/pgtable.h > +++ b/arch/riscv/include/asm/pgtable.h > @@ -462,6 +462,32 @@ static inline int ptep_clear_flush_young(struct vm_area_struct *vma, > return ptep_test_and_clear_young(vma, address, ptep); > } > > +#define pgprot_noncached pgprot_noncached > +static inline pgprot_t pgprot_noncached(pgprot_t _prot) > +{ > + unsigned long prot = pgprot_val(_prot); > + > + prot &= ~_PAGE_DMA_MASK; > + prot |= _PAGE_DMA_IO; > + > + return __pgprot(prot); > +} > + > +#define pgprot_writecombine pgprot_writecombine > +static inline pgprot_t pgprot_writecombine(pgprot_t _prot) > +{ > + unsigned long prot = pgprot_val(_prot); > + > + prot &= ~_PAGE_DMA_MASK; > + prot |= _PAGE_DMA_WC; > + > + return __pgprot(prot); > +} > + > +#define __HAVE_PHYS_MEM_ACCESS_PROT > +extern pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > + unsigned long size, pgprot_t vma_prot); > + > /* > * Encode and decode a swap entry > * > diff --git a/arch/riscv/include/asm/sbi.h b/arch/riscv/include/asm/sbi.h > index 0d42693..133e88a 100644 > --- a/arch/riscv/include/asm/sbi.h > +++ b/arch/riscv/include/asm/sbi.h > @@ -27,6 +27,7 @@ enum sbi_ext_id { > SBI_EXT_IPI = 0x735049, > SBI_EXT_RFENCE = 0x52464E43, > SBI_EXT_HSM = 0x48534D, > + SBI_EXT_DMA = 0xAB150401, > }; > > enum sbi_ext_base_fid { > @@ -63,6 +64,17 @@ enum sbi_ext_hsm_fid { > SBI_EXT_HSM_HART_STATUS, > }; > > +enum sbi_ext_dma_fid { > + SBI_DMA_SYNC = 0, > +}; > + > +enum sbi_dma_sync_data_direction { > + SBI_DMA_BIDIRECTIONAL = 0, > + SBI_DMA_TO_DEVICE = 1, > + SBI_DMA_FROM_DEVICE = 2, > + SBI_DMA_NONE = 3, > +}; > + > enum sbi_hsm_hart_status { > SBI_HSM_HART_STATUS_STARTED = 0, > SBI_HSM_HART_STATUS_STOPPED, > @@ -128,6 +140,9 @@ int sbi_remote_hfence_vvma_asid(const unsigned long *hart_mask, > unsigned long size, > unsigned long asid); > int sbi_probe_extension(int ext); > +void sbi_dma_sync(unsigned long start, > + unsigned long size, > + enum sbi_dma_sync_data_direction dir); > > /* Check if current SBI specification version is 0.1 or not */ > static inline int sbi_spec_is_0_1(void) > diff --git a/arch/riscv/kernel/sbi.c b/arch/riscv/kernel/sbi.c > index 7402a41..c936019 100644 > --- a/arch/riscv/kernel/sbi.c > +++ b/arch/riscv/kernel/sbi.c > @@ -521,6 +521,25 @@ int sbi_probe_extension(int extid) > } > EXPORT_SYMBOL(sbi_probe_extension); > > +void sbi_dma_sync(unsigned long start, > + unsigned long size, > + enum sbi_dma_sync_data_direction dir) > +{ > +#if 0 > + sbi_ecall(SBI_EXT_DMA, SBI_DMA_SYNC, start, size, dir, > + 0, 0, 0); > +#else > + /* Just for try, it should be in sbi ecall and will be removed before merged */ > + register unsigned long i asm("a0") = start & ~(L1_CACHE_BYTES - 1); > + > + for (; i < ALIGN(start + size, L1_CACHE_BYTES); i += L1_CACHE_BYTES) > + __asm__ __volatile__(".long 0x02b5000b"); > + Hi, I'm trying to use this patch for my D1 board. Though the above code will be removed, I notice that the use of the inline assembly is wrong and `i` (i.e. `a0`) might not be correctly passed to the assembly code when we are using some other compilers. It should be `__asm__ __volatile__(".long 0x02b5000b" : : "r"(i))`. Thanks, Wende > + __asm__ __volatile__(".long 0x01b0000b"); > +#endif > +} > +EXPORT_SYMBOL(sbi_dma_sync); > + > static long __sbi_base_ecall(int fid) > { > struct sbiret ret; > diff --git a/arch/riscv/mm/Makefile b/arch/riscv/mm/Makefile > index 7ebaef1..ca0ff90 100644 > --- a/arch/riscv/mm/Makefile > +++ b/arch/riscv/mm/Makefile > @@ -13,6 +13,7 @@ obj-y += extable.o > obj-$(CONFIG_MMU) += fault.o pageattr.o > obj-y += cacheflush.o > obj-y += context.o > +obj-y += dma-mapping.o > > ifeq ($(CONFIG_MMU),y) > obj-$(CONFIG_SMP) += tlbflush.o > diff --git a/arch/riscv/mm/dma-mapping.c b/arch/riscv/mm/dma-mapping.c > new file mode 100644 > index 00000000..4afd9dc > --- /dev/null > +++ b/arch/riscv/mm/dma-mapping.c > @@ -0,0 +1,53 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include > +#include > + > +void arch_dma_prep_coherent(struct page *page, size_t size) > +{ > + void *ptr = page_address(page); > + > + memset(ptr, 0, size); > + sbi_dma_sync(page_to_phys(page), size, SBI_DMA_BIDIRECTIONAL); > +} > + > +void arch_sync_dma_for_device(phys_addr_t paddr, size_t size, > + enum dma_data_direction dir) > +{ > + switch (dir) { > + case DMA_TO_DEVICE: > + case DMA_FROM_DEVICE: > + case DMA_BIDIRECTIONAL: > + sbi_dma_sync(paddr, size, dir); > + break; > + default: > + BUG(); > + } > +} > + > +void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size, > + enum dma_data_direction dir) > +{ > + switch (dir) { > + case DMA_TO_DEVICE: > + return; > + case DMA_FROM_DEVICE: > + case DMA_BIDIRECTIONAL: > + sbi_dma_sync(paddr, size, dir); > + break; > + default: > + BUG(); > + } > +} > + > +pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn, > + unsigned long size, pgprot_t vma_prot) > +{ > + if (!pfn_valid(pfn)) > + return pgprot_noncached(vma_prot); > + else if (file->f_flags & O_SYNC) > + return pgprot_writecombine(vma_prot); > + > + return vma_prot; > +} > +EXPORT_SYMBOL(phys_mem_access_prot); -- Best wishes! Sincerely, twd2 https://twd2.me