diff options
Diffstat (limited to 'arch/avr32')
| -rw-r--r-- | arch/avr32/cpu/at32ap700x/Makefile | 2 | ||||
| -rw-r--r-- | arch/avr32/cpu/at32ap700x/mmu.c | 78 | ||||
| -rw-r--r-- | arch/avr32/cpu/start.S | 19 | ||||
| -rw-r--r-- | arch/avr32/include/asm/arch-at32ap700x/addrspace.h | 5 | ||||
| -rw-r--r-- | arch/avr32/include/asm/arch-at32ap700x/mmu.h | 66 | ||||
| -rw-r--r-- | arch/avr32/lib/board.c | 4 |
6 files changed, 163 insertions, 11 deletions
diff --git a/arch/avr32/cpu/at32ap700x/Makefile b/arch/avr32/cpu/at32ap700x/Makefile index 46e6ef6..30ea925 100644 --- a/arch/avr32/cpu/at32ap700x/Makefile +++ b/arch/avr32/cpu/at32ap700x/Makefile @@ -24,7 +24,7 @@ include $(TOPDIR)/config.mk LIB := $(obj)lib$(SOC).a -COBJS := portmux.o clk.o +COBJS := portmux.o clk.o mmu.o SRCS := $(SOBJS:.o=.S) $(COBJS:.o=.c) OBJS := $(addprefix $(obj),$(SOBJS) $(COBJS)) diff --git a/arch/avr32/cpu/at32ap700x/mmu.c b/arch/avr32/cpu/at32ap700x/mmu.c new file mode 100644 index 0000000..c3a1b93 --- /dev/null +++ b/arch/avr32/cpu/at32ap700x/mmu.c @@ -0,0 +1,78 @@ +#include <common.h> +#include <asm/arch/mmu.h> +#include <asm/sysreg.h> + +void mmu_init_r(unsigned long dest_addr) +{ + uintptr_t vmr_table_addr; + + /* Round monitor address down to the nearest page boundary */ + dest_addr &= PAGE_ADDR_MASK; + + /* Initialize TLB entry 0 to cover the monitor, and lock it */ + sysreg_write(TLBEHI, dest_addr | SYSREG_BIT(TLBEHI_V)); + sysreg_write(TLBELO, dest_addr | MMU_VMR_CACHE_WRBACK); + sysreg_write(MMUCR, SYSREG_BF(DRP, 0) | SYSREG_BF(DLA, 1) + | SYSREG_BIT(MMUCR_S) | SYSREG_BIT(M)); + __builtin_tlbw(); + + /* + * Calculate the address of the VM range table in a PC-relative + * manner to make sure we hit the SDRAM and not the flash. + */ + vmr_table_addr = (uintptr_t)&mmu_vmr_table; + sysreg_write(PTBR, vmr_table_addr); + printf("VMR table @ 0x%08x\n", vmr_table_addr); + + /* Enable paging */ + sysreg_write(MMUCR, SYSREG_BF(DRP, 1) | SYSREG_BF(DLA, 1) + | SYSREG_BIT(MMUCR_S) | SYSREG_BIT(M) | SYSREG_BIT(E)); +} + +int mmu_handle_tlb_miss(void) +{ + const struct mmu_vm_range *vmr_table; + const struct mmu_vm_range *vmr; + unsigned int fault_pgno; + int first, last; + + fault_pgno = sysreg_read(TLBEAR) >> PAGE_SHIFT; + vmr_table = (const struct mmu_vm_range *)sysreg_read(PTBR); + + /* Do a binary search through the VM ranges */ + first = 0; + last = CONFIG_SYS_NR_VM_REGIONS; + while (first < last) { + unsigned int start; + int middle; + + /* Pick the entry in the middle of the remaining range */ + middle = (first + last) >> 1; + vmr = &vmr_table[middle]; + start = vmr->virt_pgno; + + /* Do the bisection thing */ + if (fault_pgno < start) { + last = middle; + } else if (fault_pgno >= (start + vmr->nr_pages)) { + first = middle + 1; + } else { + /* Got it; let's slam it into the TLB */ + uint32_t tlbelo; + + tlbelo = vmr->phys & ~PAGE_ADDR_MASK; + tlbelo |= fault_pgno << PAGE_SHIFT; + sysreg_write(TLBELO, tlbelo); + __builtin_tlbw(); + + /* Zero means success */ + return 0; + } + } + + /* + * Didn't find any matching entries. Return a nonzero value to + * indicate that this should be treated as a fatal exception. + */ + return -1; +} diff --git a/arch/avr32/cpu/start.S b/arch/avr32/cpu/start.S index 99c9e06..06bf4c6 100644 --- a/arch/avr32/cpu/start.S +++ b/arch/avr32/cpu/start.S @@ -82,12 +82,19 @@ _evba: .org 0x44 rjmp unknown_exception /* DTLB Modified */ - .org 0x50 - rjmp unknown_exception /* ITLB Miss */ - .org 0x60 - rjmp unknown_exception /* DTLB Miss (read) */ - .org 0x70 - rjmp unknown_exception /* DTLB Miss (write) */ + .org 0x50 /* ITLB Miss */ + pushm r8-r12,lr + rjmp 1f + .org 0x60 /* DTLB Miss (read) */ + pushm r8-r12,lr + rjmp 1f + .org 0x70 /* DTLB Miss (write) */ + pushm r8-r12,lr +1: mov r12, sp + rcall mmu_handle_tlb_miss + popm r8-r12,lr + brne unknown_exception + rete .size _evba, . - _evba diff --git a/arch/avr32/include/asm/arch-at32ap700x/addrspace.h b/arch/avr32/include/asm/arch-at32ap700x/addrspace.h index 409eee3..4edc1bd 100644 --- a/arch/avr32/include/asm/arch-at32ap700x/addrspace.h +++ b/arch/avr32/include/asm/arch-at32ap700x/addrspace.h @@ -75,10 +75,7 @@ static inline void * phys_to_virt(unsigned long address) static inline void * map_physmem(phys_addr_t paddr, unsigned long len, unsigned long flags) { - if (flags == MAP_WRBACK) - return (void *)P1SEGADDR(paddr); - else - return (void *)P2SEGADDR(paddr); + return (void *)paddr; } #endif /* __ASM_AVR32_ADDRSPACE_H */ diff --git a/arch/avr32/include/asm/arch-at32ap700x/mmu.h b/arch/avr32/include/asm/arch-at32ap700x/mmu.h new file mode 100644 index 0000000..fcd9a05 --- /dev/null +++ b/arch/avr32/include/asm/arch-at32ap700x/mmu.h @@ -0,0 +1,66 @@ +/* + * In order to deal with the hardcoded u-boot requirement that virtual + * addresses are always mapped 1:1 with physical addresses, we implement + * a small virtual memory manager so that we can use the MMU hardware in + * order to get the caching properties right. + * + * A few pages (or possibly just one) are locked in the TLB permanently + * in order to avoid recursive TLB misses, but most pages are faulted in + * on demand. + */ +#ifndef __ASM_ARCH_MMU_H +#define __ASM_ARCH_MMU_H + +#include <asm/sysreg.h> + +#define PAGE_SHIFT 20 +#define PAGE_SIZE (1UL << PAGE_SHIFT) +#define PAGE_ADDR_MASK (~(PAGE_SIZE - 1)) + +#define MMU_VMR_CACHE_NONE \ + (SYSREG_BF(AP, 3) | SYSREG_BF(SZ, 3) | SYSREG_BIT(TLBELO_D)) +#define MMU_VMR_CACHE_WBUF \ + (MMU_VMR_CACHE_NONE | SYSREG_BIT(B)) +#define MMU_VMR_CACHE_WRTHRU \ + (MMU_VMR_CACHE_NONE | SYSREG_BIT(TLBELO_C) | SYSREG_BIT(W)) +#define MMU_VMR_CACHE_WRBACK \ + (MMU_VMR_CACHE_WBUF | SYSREG_BIT(TLBELO_C)) + +/* + * This structure is used in our "page table". Instead of the usual + * x86-inspired radix tree, we let each entry cover an arbitrary-sized + * virtual address range and store them in a binary search tree. This is + * somewhat slower, but should use significantly less RAM, and we + * shouldn't get many TLB misses when using 1 MB pages anyway. + * + * With 1 MB pages, we need 12 bits to store the page number. In + * addition, we stick an Invalid bit in the high bit of virt_pgno (if + * set, it cannot possibly match any faulting page), and all the bits + * that need to be written to TLBELO in phys_pgno. + */ +struct mmu_vm_range { + uint16_t virt_pgno; + uint16_t nr_pages; + uint32_t phys; +}; + +/* + * An array of mmu_vm_range objects describing all pageable addresses. + * The array is sorted by virt_pgno so that the TLB miss exception + * handler can do a binary search to find the correct entry. + */ +extern struct mmu_vm_range mmu_vmr_table[]; + +/* + * Initialize the MMU. This will set up a fixed TLB entry for the static + * u-boot image at dest_addr and enable paging. + */ +void mmu_init_r(unsigned long dest_addr); + +/* + * Handle a TLB miss exception. This function is called directly from + * the exception vector table written in assembly. + */ +int mmu_handle_tlb_miss(void); + +#endif /* __ASM_ARCH_MMU_H */ diff --git a/arch/avr32/lib/board.c b/arch/avr32/lib/board.c index 9e741d2..aa589bb 100644 --- a/arch/avr32/lib/board.c +++ b/arch/avr32/lib/board.c @@ -33,6 +33,7 @@ #include <asm/initcalls.h> #include <asm/sections.h> +#include <asm/arch/mmu.h> #ifndef CONFIG_IDENT_STRING #define CONFIG_IDENT_STRING "" @@ -265,6 +266,9 @@ void board_init_r(gd_t *new_gd, ulong dest_addr) gd->flags |= GD_FLG_RELOC; gd->reloc_off = dest_addr - CONFIG_SYS_MONITOR_BASE; + /* Enable the MMU so that we can keep u-boot simple */ + mmu_init_r(dest_addr); + board_early_init_r(); monitor_flash_len = _edata - _text; |