diff mbox series

[05/12] riscv: Implement non-coherent DMA support via SiFive cache flushing

Message ID 20230211031821.976408-6-cristian.ciocaltea@collabora.com
State New
Headers
Series Enable networking support for StarFive JH7100 SoC |

Commit Message

Cristian Ciocaltea Feb. 11, 2023, 3:18 a.m. UTC 
  From: Emil Renner Berthing <kernel@esmil.dk>

This variant is used on the StarFive JH7100 SoC.

Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
---
 arch/riscv/Kconfig              |  6 ++++--
 arch/riscv/mm/dma-noncoherent.c | 37 +++++++++++++++++++++++++++++++--
 2 files changed, 39 insertions(+), 4 deletions(-)

Comments

Ben Dooks Feb. 13, 2023, 8:30 a.m. UTC | #1 
On 11/02/2023 03:18, Cristian Ciocaltea wrote:
> From: Emil Renner Berthing <kernel@esmil.dk>
> 
> This variant is used on the StarFive JH7100 SoC.
> 
> Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
> ---
>   arch/riscv/Kconfig              |  6 ++++--
>   arch/riscv/mm/dma-noncoherent.c | 37 +++++++++++++++++++++++++++++++--
>   2 files changed, 39 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 9c687da7756d..05f6c77faf6f 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -232,12 +232,14 @@ config LOCKDEP_SUPPORT
>   	def_bool y
>   
>   config RISCV_DMA_NONCOHERENT
> -	bool
> +	bool "Support non-coherent DMA"
> +	default SOC_STARFIVE
>   	select ARCH_HAS_DMA_PREP_COHERENT
> +	select ARCH_HAS_DMA_SET_UNCACHED
> +	select ARCH_HAS_DMA_CLEAR_UNCACHED
>   	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
>   	select ARCH_HAS_SYNC_DMA_FOR_CPU
>   	select ARCH_HAS_SETUP_DMA_OPS
> -	select DMA_DIRECT_REMAP
>   
>   config AS_HAS_INSN
>   	def_bool $(as-instr,.insn r 51$(comma) 0$(comma) 0$(comma) t0$(comma) t0$(comma) zero)
> diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
> index d919efab6eba..e07e53aea537 100644
> --- a/arch/riscv/mm/dma-noncoherent.c
> +++ b/arch/riscv/mm/dma-noncoherent.c
> @@ -9,14 +9,21 @@
>   #include <linux/dma-map-ops.h>
>   #include <linux/mm.h>
>   #include <asm/cacheflush.h>
> +#include <soc/sifive/sifive_ccache.h>
>   
>   static bool noncoherent_supported;
>   
>   void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
>   			      enum dma_data_direction dir)
>   {
> -	void *vaddr = phys_to_virt(paddr);
> +	void *vaddr;
>   
> +	if (sifive_ccache_handle_noncoherent()) {
> +		sifive_ccache_flush_range(paddr, size);
> +		return;
> +	}
> +
> +	vaddr = phys_to_virt(paddr);
>   	switch (dir) {
>   	case DMA_TO_DEVICE:
>   		ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
> @@ -35,8 +42,14 @@ void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
>   void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
>   			   enum dma_data_direction dir)
>   {
> -	void *vaddr = phys_to_virt(paddr);
> +	void *vaddr;
> +
> +	if (sifive_ccache_handle_noncoherent()) {
> +		sifive_ccache_flush_range(paddr, size);
> +		return;
> +	}

ok, what happens if we have an system where the ccache and another level
of cache also requires maintenance operations?

>   
> +	vaddr = phys_to_virt(paddr);
>   	switch (dir) {
>   	case DMA_TO_DEVICE:
>   		break;
> @@ -49,10 +62,30 @@ void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
>   	}
>   }
>   
> +void *arch_dma_set_uncached(void *addr, size_t size)
> +{
> +	if (sifive_ccache_handle_noncoherent())
> +		return sifive_ccache_set_uncached(addr, size);
> +
> +	return addr;
> +}
> +
> +void arch_dma_clear_uncached(void *addr, size_t size)
> +{
> +	if (sifive_ccache_handle_noncoherent())
> +		sifive_ccache_clear_uncached(addr, size);
> +}
> +
>   void arch_dma_prep_coherent(struct page *page, size_t size)
>   {
>   	void *flush_addr = page_address(page);
>   
> +	if (sifive_ccache_handle_noncoherent()) {
> +		memset(flush_addr, 0, size);
> +		sifive_ccache_flush_range(__pa(flush_addr), size);
> +		return;
> +	}
> +
>   	ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size);
>   }
>
Cristian Ciocaltea Feb. 14, 2023, 6:06 p.m. UTC | #2 
On 2/13/23 10:30, Ben Dooks wrote:
> On 11/02/2023 03:18, Cristian Ciocaltea wrote:
>> From: Emil Renner Berthing <kernel@esmil.dk>
>>
>> This variant is used on the StarFive JH7100 SoC.
>>
>> Signed-off-by: Emil Renner Berthing <kernel@esmil.dk>
>> Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
>> ---
>>   arch/riscv/Kconfig              |  6 ++++--
>>   arch/riscv/mm/dma-noncoherent.c | 37 +++++++++++++++++++++++++++++++--
>>   2 files changed, 39 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
>> index 9c687da7756d..05f6c77faf6f 100644
>> --- a/arch/riscv/Kconfig
>> +++ b/arch/riscv/Kconfig
>> @@ -232,12 +232,14 @@ config LOCKDEP_SUPPORT
>>       def_bool y
>>   config RISCV_DMA_NONCOHERENT
>> -    bool
>> +    bool "Support non-coherent DMA"
>> +    default SOC_STARFIVE
>>       select ARCH_HAS_DMA_PREP_COHERENT
>> +    select ARCH_HAS_DMA_SET_UNCACHED
>> +    select ARCH_HAS_DMA_CLEAR_UNCACHED
>>       select ARCH_HAS_SYNC_DMA_FOR_DEVICE
>>       select ARCH_HAS_SYNC_DMA_FOR_CPU
>>       select ARCH_HAS_SETUP_DMA_OPS
>> -    select DMA_DIRECT_REMAP
>>   config AS_HAS_INSN
>>       def_bool $(as-instr,.insn r 51$(comma) 0$(comma) 0$(comma) 
>> t0$(comma) t0$(comma) zero)
>> diff --git a/arch/riscv/mm/dma-noncoherent.c 
>> b/arch/riscv/mm/dma-noncoherent.c
>> index d919efab6eba..e07e53aea537 100644
>> --- a/arch/riscv/mm/dma-noncoherent.c
>> +++ b/arch/riscv/mm/dma-noncoherent.c
>> @@ -9,14 +9,21 @@
>>   #include <linux/dma-map-ops.h>
>>   #include <linux/mm.h>
>>   #include <asm/cacheflush.h>
>> +#include <soc/sifive/sifive_ccache.h>
>>   static bool noncoherent_supported;
>>   void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
>>                     enum dma_data_direction dir)
>>   {
>> -    void *vaddr = phys_to_virt(paddr);
>> +    void *vaddr;
>> +    if (sifive_ccache_handle_noncoherent()) {
>> +        sifive_ccache_flush_range(paddr, size);
>> +        return;
>> +    }
>> +
>> +    vaddr = phys_to_virt(paddr);
>>       switch (dir) {
>>       case DMA_TO_DEVICE:
>>           ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
>> @@ -35,8 +42,14 @@ void arch_sync_dma_for_device(phys_addr_t paddr, 
>> size_t size,
>>   void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
>>                  enum dma_data_direction dir)
>>   {
>> -    void *vaddr = phys_to_virt(paddr);
>> +    void *vaddr;
>> +
>> +    if (sifive_ccache_handle_noncoherent()) {
>> +        sifive_ccache_flush_range(paddr, size);
>> +        return;
>> +    }
> 
> ok, what happens if we have an system where the ccache and another level
> of cache also requires maintenance operations?

According to [1], the handling of non-coherent DMA on RISC-V is 
currently being worked on, so I will respin the series as soon as the 
proper support arrives.

[1] https://lore.kernel.org/lkml/Y+d36nz0xdfXmDI1@spud/


>> +    vaddr = phys_to_virt(paddr);
>>       switch (dir) {
>>       case DMA_TO_DEVICE:
>>           break;
>> @@ -49,10 +62,30 @@ void arch_sync_dma_for_cpu(phys_addr_t paddr, 
>> size_t size,
>>       }
>>   }
>> +void *arch_dma_set_uncached(void *addr, size_t size)
>> +{
>> +    if (sifive_ccache_handle_noncoherent())
>> +        return sifive_ccache_set_uncached(addr, size);
>> +
>> +    return addr;
>> +}
>> +
>> +void arch_dma_clear_uncached(void *addr, size_t size)
>> +{
>> +    if (sifive_ccache_handle_noncoherent())
>> +        sifive_ccache_clear_uncached(addr, size);
>> +}
>> +
>>   void arch_dma_prep_coherent(struct page *page, size_t size)
>>   {
>>       void *flush_addr = page_address(page);
>> +    if (sifive_ccache_handle_noncoherent()) {
>> +        memset(flush_addr, 0, size);
>> +        sifive_ccache_flush_range(__pa(flush_addr), size);
>> +        return;
>> +    }
>> +
>>       ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size);
>>   }
>
Conor Dooley Feb. 14, 2023, 6:17 p.m. UTC | #3 
On Tue, Feb 14, 2023 at 08:06:49PM +0200, Cristian Ciocaltea wrote:
> On 2/13/23 10:30, Ben Dooks wrote:
> > On 11/02/2023 03:18, Cristian Ciocaltea wrote:
> > > From: Emil Renner Berthing <kernel@esmil.dk>

> > > diff --git a/arch/riscv/mm/dma-noncoherent.c
> > > b/arch/riscv/mm/dma-noncoherent.c
> > > index d919efab6eba..e07e53aea537 100644
> > > --- a/arch/riscv/mm/dma-noncoherent.c
> > > +++ b/arch/riscv/mm/dma-noncoherent.c
> > > @@ -9,14 +9,21 @@
> > >   #include <linux/dma-map-ops.h>
> > >   #include <linux/mm.h>
> > >   #include <asm/cacheflush.h>
> > > +#include <soc/sifive/sifive_ccache.h>
> > >   static bool noncoherent_supported;
> > >   void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
> > >                     enum dma_data_direction dir)
> > >   {
> > > -    void *vaddr = phys_to_virt(paddr);
> > > +    void *vaddr;
> > > +    if (sifive_ccache_handle_noncoherent()) {
> > > +        sifive_ccache_flush_range(paddr, size);
> > > +        return;
> > > +    }
> > > +
> > > +    vaddr = phys_to_virt(paddr);
> > >       switch (dir) {
> > >       case DMA_TO_DEVICE:
> > >           ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
> > > @@ -35,8 +42,14 @@ void arch_sync_dma_for_device(phys_addr_t paddr,
> > > size_t size,
> > >   void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
> > >                  enum dma_data_direction dir)
> > >   {
> > > -    void *vaddr = phys_to_virt(paddr);
> > > +    void *vaddr;
> > > +
> > > +    if (sifive_ccache_handle_noncoherent()) {
> > > +        sifive_ccache_flush_range(paddr, size);
> > > +        return;
> > > +    }
> > 
> > ok, what happens if we have an system where the ccache and another level
> > of cache also requires maintenance operations?

TBH, I'd hope that a system with that complexity is also not trying to
manage the cache in this manner!

> According to [1], the handling of non-coherent DMA on RISC-V is currently
> being worked on, so I will respin the series as soon as the proper support
> arrives.

But yeah, once that stuff lands we can carry out these operations only
for the platforms that need/"need" it.

Cheers,
Conor.
diff mbox series

Patch

diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
index 9c687da7756d..05f6c77faf6f 100644
--- a/arch/riscv/Kconfig
+++ b/arch/riscv/Kconfig
@@ -232,12 +232,14 @@  config LOCKDEP_SUPPORT
 	def_bool y
 
 config RISCV_DMA_NONCOHERENT
-	bool
+	bool "Support non-coherent DMA"
+	default SOC_STARFIVE
 	select ARCH_HAS_DMA_PREP_COHERENT
+	select ARCH_HAS_DMA_SET_UNCACHED
+	select ARCH_HAS_DMA_CLEAR_UNCACHED
 	select ARCH_HAS_SYNC_DMA_FOR_DEVICE
 	select ARCH_HAS_SYNC_DMA_FOR_CPU
 	select ARCH_HAS_SETUP_DMA_OPS
-	select DMA_DIRECT_REMAP
 
 config AS_HAS_INSN
 	def_bool $(as-instr,.insn r 51$(comma) 0$(comma) 0$(comma) t0$(comma) t0$(comma) zero)
diff --git a/arch/riscv/mm/dma-noncoherent.c b/arch/riscv/mm/dma-noncoherent.c
index d919efab6eba..e07e53aea537 100644
--- a/arch/riscv/mm/dma-noncoherent.c
+++ b/arch/riscv/mm/dma-noncoherent.c
@@ -9,14 +9,21 @@ 
 #include <linux/dma-map-ops.h>
 #include <linux/mm.h>
 #include <asm/cacheflush.h>
+#include <soc/sifive/sifive_ccache.h>
 
 static bool noncoherent_supported;
 
 void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
 			      enum dma_data_direction dir)
 {
-	void *vaddr = phys_to_virt(paddr);
+	void *vaddr;
 
+	if (sifive_ccache_handle_noncoherent()) {
+		sifive_ccache_flush_range(paddr, size);
+		return;
+	}
+
+	vaddr = phys_to_virt(paddr);
 	switch (dir) {
 	case DMA_TO_DEVICE:
 		ALT_CMO_OP(clean, vaddr, size, riscv_cbom_block_size);
@@ -35,8 +42,14 @@  void arch_sync_dma_for_device(phys_addr_t paddr, size_t size,
 void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
 			   enum dma_data_direction dir)
 {
-	void *vaddr = phys_to_virt(paddr);
+	void *vaddr;
+
+	if (sifive_ccache_handle_noncoherent()) {
+		sifive_ccache_flush_range(paddr, size);
+		return;
+	}
 
+	vaddr = phys_to_virt(paddr);
 	switch (dir) {
 	case DMA_TO_DEVICE:
 		break;
@@ -49,10 +62,30 @@  void arch_sync_dma_for_cpu(phys_addr_t paddr, size_t size,
 	}
 }
 
+void *arch_dma_set_uncached(void *addr, size_t size)
+{
+	if (sifive_ccache_handle_noncoherent())
+		return sifive_ccache_set_uncached(addr, size);
+
+	return addr;
+}
+
+void arch_dma_clear_uncached(void *addr, size_t size)
+{
+	if (sifive_ccache_handle_noncoherent())
+		sifive_ccache_clear_uncached(addr, size);
+}
+
 void arch_dma_prep_coherent(struct page *page, size_t size)
 {
 	void *flush_addr = page_address(page);
 
+	if (sifive_ccache_handle_noncoherent()) {
+		memset(flush_addr, 0, size);
+		sifive_ccache_flush_range(__pa(flush_addr), size);
+		return;
+	}
+
 	ALT_CMO_OP(flush, flush_addr, size, riscv_cbom_block_size);
 }