[PATCH v2 3/4] riscv: Provide a mechanism for riscv boards to parse reserved memory

[Bin Meng]

Hi Atish,

On Sat, Mar 14, 2020 at 8:54 AM Atish Patra <atishp at atishpatra.org> wrote:
>
> On Fri, Mar 13, 2020 at 5:12 PM Atish Patra <atish.patra at wdc.com> wrote:
> >
> > In RISC-V, M-mode software can reserve physical memory regions
> > by setting appropriate physical memory protection (PMP) csr. As the
> > PMP csr are accessible only in M-mode, S-mode U-Boot can not read
> > this configuration directly. However, M-mode software can pass this
> > information via reserved-memory node in device tree so that S-mode
> > software can access this information.
> >
> > In U-boot, any board may use the DT in following ways.

nits: U-Boot

> > 1. OF_SEPARTE: It ignores the DT from previous stage and uses the DT

typo: OF_SEPARATE

> > from U-Boot sources.
> > 2. OF_PRIOR_STATE: It reuses the DT from previous stage.

typo: OF_PRIOR_STAGE

> > For case 1: U-Boot needs to parse the reserved-memory node from the
> > DT passed from the previous stage and update the DT in use.
> >
> > This patch provides a framework to do that from any RISC-V boards.
> >
> > Signed-off-by: Atish Patra <atish.patra at wdc.com>
> > ---
> >  arch/riscv/cpu/start.S                |  1 +
> >  arch/riscv/include/asm/global_data.h  |  1 +
> >  arch/riscv/include/asm/u-boot-riscv.h |  1 +
> >  arch/riscv/lib/asm-offsets.c          |  1 +
> >  arch/riscv/lib/bootm.c                | 37 +++++++++++++++++++++++++++
> >  5 files changed, 41 insertions(+)
> >
> > diff --git a/arch/riscv/cpu/start.S b/arch/riscv/cpu/start.S
> > index 6b3ff99c3882..0282685c2906 100644
> > --- a/arch/riscv/cpu/start.S
> > +++ b/arch/riscv/cpu/start.S
> > @@ -121,6 +121,7 @@ call_board_init_f_0:
> >
> >         jal     board_init_f_init_reserve
> >
> > +       SREG    s1, GD_FIRMWARE_FDT_ADDR(gp)
> >         /* save the boot hart id to global_data */
> >         SREG    tp, GD_BOOT_HART(gp)
> >
> > diff --git a/arch/riscv/include/asm/global_data.h b/arch/riscv/include/asm/global_data.h
> > index b74bd7e738bb..51ac8d1c98e2 100644
> > --- a/arch/riscv/include/asm/global_data.h
> > +++ b/arch/riscv/include/asm/global_data.h
> > @@ -15,6 +15,7 @@
> >  /* Architecture-specific global data */
> >  struct arch_global_data {
> >         long boot_hart;         /* boot hart id */
> > +       phys_addr_t firmware_fdt_addr;
> >  #ifdef CONFIG_SIFIVE_CLINT
> >         void __iomem *clint;    /* clint base address */
> >  #endif
> > diff --git a/arch/riscv/include/asm/u-boot-riscv.h b/arch/riscv/include/asm/u-boot-riscv.h
> > index 49febd588102..b7bea0ba184d 100644
> > --- a/arch/riscv/include/asm/u-boot-riscv.h
> > +++ b/arch/riscv/include/asm/u-boot-riscv.h
> > @@ -17,5 +17,6 @@ int cleanup_before_linux(void);
> >  /* board/.../... */
> >  int board_init(void);
> >  void board_quiesce_devices(void);
> > +int riscv_board_reserved_mem_fixup(void *fdt);
> >
> >  #endif /* _U_BOOT_RISCV_H_ */
> > diff --git a/arch/riscv/lib/asm-offsets.c b/arch/riscv/lib/asm-offsets.c
> > index 4fa4fd371473..7301c1b98e23 100644
> > --- a/arch/riscv/lib/asm-offsets.c
> > +++ b/arch/riscv/lib/asm-offsets.c
> > @@ -14,6 +14,7 @@
> >  int main(void)
> >  {
> >         DEFINE(GD_BOOT_HART, offsetof(gd_t, arch.boot_hart));
> > +       DEFINE(GD_FIRMWARE_FDT_ADDR, offsetof(gd_t, arch.firmware_fdt_addr));
> >  #ifndef CONFIG_XIP
> >         DEFINE(GD_AVAILABLE_HARTS, offsetof(gd_t, arch.available_harts));
> >  #endif
> > diff --git a/arch/riscv/lib/bootm.c b/arch/riscv/lib/bootm.c
> > index f927694ae32f..3a4d0bf14c86 100644
> > --- a/arch/riscv/lib/bootm.c
> > +++ b/arch/riscv/lib/bootm.c
> > @@ -19,6 +19,7 @@
> >  #include <dm/device.h>
> >  #include <dm/root.h>
> >  #include <u-boot/zlib.h>
> > +#include <mapmem.h>
> >
> >  DECLARE_GLOBAL_DATA_PTR;
> >
> > @@ -26,6 +27,42 @@ __weak void board_quiesce_devices(void)
> >  {
> >  }
> >
> > +int riscv_board_reserved_mem_fixup(void *fdt)
> > +{
> > +       uint32_t phandle;
> > +       struct fdt_memory pmp_mem;
> > +       int err;
> > +       void *src_fdt_addr;
> > +       int offset, node;
> > +       phys_addr_t addr, size;
> > +
> > +       src_fdt_addr = map_sysmem(gd->arch.firmware_fdt_addr, 0);
> > +       offset = fdt_path_offset(src_fdt_addr, "/reserved-memory");
> > +       if (offset < 0) {
> > +               printf("No reserved memory region found in FDT\n");
> > +               return offset;

We should return 0 to allow cases that do not have /reserved-memory
node. Otherwise we are mandating a newer OpenSBI version to work with
us.

> > +       }
> > +
> > +       fdt_for_each_subnode(node, src_fdt_addr, offset) {
> > +               const char *name = fdt_get_name(src_fdt_addr, node, NULL);
> > +
> > +               addr = fdtdec_get_addr_size(src_fdt_addr, node, "reg", &size);
> > +               if (addr == FDT_ADDR_T_NONE) {
> > +                       debug("failed to read address/size for %s\n", name);
> > +                       continue;
> > +               }
> > +               pmp_mem.start = addr;
> > +               pmp_mem.end = addr + size;
> > +               err = fdtdec_add_reserved_memory(fdt, name, &pmp_mem, &phandle);
> > +               if (err < 0) {
> > +                       printf("failed to add reserved memory: %d\n", err);
> > +                       return err;
> > +               }
> > +       }
> > +
> > +       return 0;
> > +}
> > +
> >  int arch_fixup_fdt(void *blob)
> >  {
> >         u32 size;
> > --

Regards,
Bin