回复:[PATCH 4/6] MIPS: Loongson: Add DMA support for 7A1000

[Jiaxun Yang <jiaxun.yang@flygoat.com>]

 ---- 在 星期一, 2020-03-09 16:23:24 Tiezhu Yang <yangtiezhu@loongson.cn> 撰写 ----
 > Implement __phys_to_dma() and __dma_to_phys() according to the
 > node id offset in 7A1000 DMA route config register.

That design shocked me a lot. And It is known that some firmware didn't configure
HT Recieve window correctly to make it work. So probably for mainline kernel,
just set DMA_MASK to limit LS7A DMA address to Node0 would be a better Option?
 
 > Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
 > ---
 >  arch/mips/include/asm/mach-loongson64/boot_param.h |  1 +
 >  arch/mips/loongson64/dma.c                         | 49 +++++++++++++++++++++-
 >  arch/mips/loongson64/init.c                        | 13 ++++++
 >  3 files changed, 61 insertions(+), 2 deletions(-)
 > 
 > diff --git a/arch/mips/include/asm/mach-loongson64/boot_param.h b/arch/mips/include/asm/mach-loongson64/boot_param.h
 > index 225a563..60e7a7e 100644
 > --- a/arch/mips/include/asm/mach-loongson64/boot_param.h
 > +++ b/arch/mips/include/asm/mach-loongson64/boot_param.h
 > @@ -218,5 +218,6 @@ struct loongson_system_configuration {
 >  extern struct efi_memory_map_loongson *loongson_memmap;
 >  extern struct loongson_system_configuration loongson_sysconf;
 >  extern struct board_devices *eboard;
 > +extern u32 node_id_offset;
 >  
 >  #endif
 > diff --git a/arch/mips/loongson64/dma.c b/arch/mips/loongson64/dma.c
 > index 5e86635..997c257 100644
 > --- a/arch/mips/loongson64/dma.c
 > +++ b/arch/mips/loongson64/dma.c
 > @@ -2,24 +2,69 @@
 >  #include <linux/dma-direct.h>
 >  #include <linux/init.h>
 >  #include <linux/swiotlb.h>
 > +#include <boot_param.h>
 >  
 > -dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
 > +struct loongson_dma_ops {
 > +    dma_addr_t (*phys_to_dma)(struct device *dev, phys_addr_t paddr);
 > +    phys_addr_t (*dma_to_phys)(struct device *dev, dma_addr_t daddr);
 > +};
 > +
 > +struct loongson_dma_ops loongson_dma;
 > +
 > +dma_addr_t __rs780e_phys_to_dma(struct device *dev, phys_addr_t paddr)
 >  {
 >      /* We extract 2bit node id (bit 44~47, only bit 44~45 used now) from
 >       * Loongson-3's 48bit address space and embed it into 40bit */
 >      long nid = (paddr >> 44) & 0x3;
 > +
 >      return ((nid << 44) ^ paddr) | (nid << 37);
 >  }
 >  
 > -phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr)
 > +dma_addr_t __ls7a_phys_to_dma(struct device *dev, phys_addr_t paddr)
 > +{
 > +    long nid = (paddr >> 44) & 0x3;
 > +
 > +    return ((nid << 44) ^ paddr) | (nid << (36 + node_id_offset));
 > +}
 > +
 > +
 > +dma_addr_t __phys_to_dma(struct device *dev, phys_addr_t paddr)
 > +{
 > +    return loongson_dma.phys_to_dma(dev, paddr);
 > +}
 > +
 > +phys_addr_t __rs780e_dma_to_phys(struct device *dev, dma_addr_t daddr)
 >  {
 >      /* We extract 2bit node id (bit 44~47, only bit 44~45 used now) from
 >       * Loongson-3's 48bit address space and embed it into 40bit */
 >      long nid = (daddr >> 37) & 0x3;
 > +
 >      return ((nid << 37) ^ daddr) | (nid << 44);
 >  }
 >  
 > +phys_addr_t __ls7a_dma_to_phys(struct device *dev, dma_addr_t daddr)
 > +{
 > +    long nid = (daddr >> (36 + node_id_offset)) & 0x3;
 > +
 > +    return ((nid << (36 + node_id_offset)) ^ daddr) | (nid << 44);
 > +}
 > +
 > +phys_addr_t __dma_to_phys(struct device *dev, dma_addr_t daddr)
 > +{
 > +    return loongson_dma.dma_to_phys(dev, daddr);
 > +}
 > +
 >  void __init plat_swiotlb_setup(void)
 >  {
 >      swiotlb_init(1);
 > +
 > +    if (strstr(eboard->name, "780E")) {
 > +        loongson_dma.phys_to_dma = __rs780e_phys_to_dma;
 > +        loongson_dma.dma_to_phys = __rs780e_dma_to_phys;
 > +    }
 > +
 > +    if (strstr(eboard->name, "7A1000")) {
 > +        loongson_dma.phys_to_dma = __ls7a_phys_to_dma;
 > +        loongson_dma.dma_to_phys = __ls7a_dma_to_phys;
 > +    }
 >  }
 > diff --git a/arch/mips/loongson64/init.c b/arch/mips/loongson64/init.c
 > index 5ac1a0f..dd8463d 100644
 > --- a/arch/mips/loongson64/init.c
 > +++ b/arch/mips/loongson64/init.c
 > @@ -12,6 +12,11 @@
 >  #include <asm/fw/fw.h>
 >  
 >  #include <loongson.h>
 > +#include <boot_param.h>
 > +
 > +#define NODE_ID_OFFSET_ADDR     0x90000E001001041CULL
 > +
 > +u32 node_id_offset;
 >  
 >  static void __init mips_nmi_setup(void)
 >  {
 > @@ -23,6 +28,11 @@ static void __init mips_nmi_setup(void)
 >      flush_icache_range((unsigned long)base, (unsigned long)base + 0x80);
 >  }
 >  
 > +static void ls7a_early_config(void)
 > +{
 > +    node_id_offset = (*(u32 *)NODE_ID_OFFSET_ADDR >> 8) & 0x1F;

Please avoid raw pointer. Use readl/writel instead.

 > +}
 > +
 >  void __init prom_init(void)
 >  {
 >      fw_init_cmdline();
 > @@ -32,6 +42,9 @@ void __init prom_init(void)
 >      set_io_port_base((unsigned long)
 >          ioremap(LOONGSON_PCIIO_BASE, LOONGSON_PCIIO_SIZE));
 >  
 > +    if (strstr(eboard->name, "7A1000"))
 > +        ls7a_early_config();
 > +
 >      prom_init_numa_memory();
 >  
 >      /* Hardcode to CPU UART 0 */
 > -- 
 > 2.1.0
 > 
 >