Extend MMU Flags to 64-bit for T-Head C906 and Svpbmt

Currently RISC-V NuttX supports 32-bit MMU Flags inside a Page Table Entry. This PR extends the MMU Flags to 64-bit, to support T-Head C906 Core and the new RISC-V Svpbmt Extension.

T-Head C906 uses Bits 59 to 63 in a Leaf Page Table Entry to configure the Memory Type: Cacheable / Bufferable / Strongly-Ordered. For the upcoming port of NuttX to PINE64 Ox64 BL808 SBC, we need to set the Memory Type to Strongly-Ordered for I/O Memory, which requires 64-bit MMU Flags.

Details of C906 MMU: https://lupyuen.github.io/articles/plic3#t-head-errata

Newer RISC-V Cores will use the Svpbmt Extension to configure the Memory Type (Cacheable / Strongly-Ordered). Svpbmt uses Bits 61 to 62 in a Leaf Page Table Entry to define the Memory Type. This also requires 64-bit MMU Flags.

Details of Svpbmt: https://github.com/riscv/riscv-isa-manual/blob/main/src/supervisor.adoc#svpbmt

arch/risc-v/src/common/riscv_mmu.c

@@ -60,7 +60,7 @@ static const size_t g_pgt_sizes[] =
  ****************************************************************************/
 
 void mmu_ln_setentry(uint32_t ptlevel, uintptr_t lnvaddr, uintptr_t paddr,
-                     uintptr_t vaddr, uint32_t mmuflags)
+                     uintptr_t vaddr, uint64_t mmuflags)
 {
   uintptr_t *lntable = (uintptr_t *)lnvaddr;
   uint32_t   index;
@@ -136,7 +136,7 @@ void mmu_ln_restore(uint32_t ptlevel, uintptr_t lnvaddr, uintptr_t vaddr,
 }
 
 void mmu_ln_map_region(uint32_t ptlevel, uintptr_t lnvaddr, uintptr_t paddr,
-                       uintptr_t vaddr, size_t size, uint32_t mmuflags)
+                       uintptr_t vaddr, size_t size, uint64_t mmuflags)
 {
   uintptr_t end_paddr = paddr + size;
   size_t    page_size = g_pgt_sizes[ptlevel - 1];

arch/risc-v/src/common/riscv_mmu.h

@@ -367,7 +367,7 @@ static inline uintptr_t mmu_get_satp_pgbase(void)
  ****************************************************************************/
 
 void mmu_ln_setentry(uint32_t ptlevel, uintptr_t lnvaddr, uintptr_t paddr,
-                     uintptr_t vaddr, uint32_t mmuflags);
+                     uintptr_t vaddr, uint64_t mmuflags);
 
 /****************************************************************************
  * Name: mmu_ln_getentry
@@ -448,7 +448,7 @@ void mmu_ln_restore(uint32_t ptlevel, uintptr_t lnvaddr, uintptr_t vaddr,
  ****************************************************************************/
 
 void mmu_ln_map_region(uint32_t ptlevel, uintptr_t lnvaddr, uintptr_t paddr,
-                       uintptr_t vaddr, size_t size, uint32_t mmuflags);
+                       uintptr_t vaddr, size_t size, uint64_t mmuflags);
 
 /****************************************************************************
  * Name: mmu_ln_map_region