libfdt seems to work

At least as far as reading memory info, cool.

One issue I have is that .(ro)data is apparently accessed by absolute
addresses, so I need to know at which address the kernel is going to be
loaded. I would prefer completely position independent code, but if
that's not possible then eh.

2 files changed, 32 insertions, 103 deletions

diff --git a/arch/riscv/init/head.S b/arch/riscv/init/head.S
index 703d265..bbd2945 100644
--- a/arch/riscv/init/head.S
+++ b/arch/riscv/init/head.S
@@ -2,9 +2,6 @@
 .global _start
 .type _start, @function
 _start:
-	/* store kernel load address */
-	auipc a4, 0
-	/* stack grows downward */
-	mv sp, a4
+	/* stack pointer is whatever? */	
 	/* go to proper init */
 	j init
diff --git a/arch/riscv/init/init.c b/arch/riscv/init/init.c
index 30c60ac..bb16876 100644
--- a/arch/riscv/init/init.c
+++ b/arch/riscv/init/init.c
@@ -1,118 +1,50 @@
 #include <apos/init.h>
 #include <apos/sizes.h>
 #include <apos/types.h>
+#include <libfdt.h>
 #include <pages.h>
 #include <csr.h>
 #include <vmap.h>
 
-struct page_ret {
-	size_t left;
-	size_t num;
-	size_t top;
+struct mem_layout {
+	pm_t base;
+	pm_t top;
 };
 
-extern void main(struct mm_pagearr_info *pageinfo);
-
-void __init init_zero(size_t ptr, size_t bytes)
+struct mem_layout get_memlayout(void *fdt)
 {
-	char *byte_ptr = (char *)ptr;
-
-	/* Not entirely sure if it would be faster to use a larget type than
-	 * char, Linux seems to have memset16/32/64 but I guess I should check
-	 * the generated assembly.
-	 */
-	while(bytes--)
-		*byte_ptr++ = 0;
-}
+	fdt32_t *size_ptr = (fdt32_t *)fdt_getprop(fdt, 0, "#size-cells", NULL);
+	fdt32_t *addr_ptr = (fdt32_t *)fdt_getprop(fdt, 0, "#address-cells", NULL);
 
-struct page_ret __init init_pages(size_t ram_size, size_t ram_top,
-		size_t page_size, size_t struct_size)
-{
-	size_t num_pages = ram_size / page_size;
-	size_t size_pages = num_pages * struct_size;
+	uint32_t size_cells = fdt32_to_cpu(*size_ptr);
+	uint32_t addr_cells = fdt32_to_cpu(*addr_ptr);
 
-	struct page_ret pageret;
-	pageret.top = ram_top - size_pages;
-	pageret.num = num_pages;
-	pageret.left = ram_size - (num_pages * page_size);
+	int mem_offset = fdt_path_offset(fdt, "/memory");
+	uint8_t *mem_reg = (uint8_t *)fdt_getprop(fdt, mem_offset, "reg", NULL);
 
-	init_zero(pageret.top, size_pages);
+	pm_t base;
+	/* if riscv128 comes around we will probably see addr_cells == 4, but
+	 * I'm not too concerned about it at the moment */
+	if (addr_cells == 2) {
+		base = fdt64_to_cpu(*(fdt64_t *)mem_reg);
+		mem_reg += sizeof(fdt64_t);
+	} else {
+		base = fdt32_to_cpu(*(fdt32_t *)mem_reg);
+		mem_reg += sizeof(fdt32_t);
+	}
 
-	return pageret;
-};
-
-size_t __init init_align_down(size_t num, size_t a)
-{
-	size_t rem = num % a;
-	return num - rem;
-}
-
-size_t __init init_align_up(size_t num, size_t a)
-{
-	return init_align_down(num, a) + a;
-}
-
-void __init init_enter_vm(unsigned long *root_page)
-{
-	asm volatile ("csrw 0x180, %0\n" "sfence.vma\n"
-			:
-			: "rK" (SATP_MODE_39 | ((unsigned long)root_page >> 12))
-			: "memory");
-}
+	pm_t top;
+	if (size_cells == 2)
+		top = fdt64_to_cpu(*(fdt64_t *)mem_reg) + base;
+	else
+		top = fdt32_to_cpu(*(fdt64_t *)mem_reg) + base;
 
-void __init call_main()
-{
-	while(1){};
+	struct mem_layout ret = {base, top};
+	return ret;
 }
 
-void __init init(void *ram_base, void *ram_top, void *initrd, void *fdt, void *boot)
+void init(void *fdt)
 {
-	size_t ram_size = ram_top - ram_base;
-
-	struct mm_pagearr_info pagearr;
-	struct page_ret pageret;
-
-	/* create crude page status map at the top of physical RAM */
-	pageret = init_pages(ram_size, (size_t)ram_top,
-			SZ_512G, sizeof(struct terapages));
-	pagearr.tera_top = (struct terapages *)pageret.top;
-	pagearr.tera_num = pageret.num;
-	
-	pageret = init_pages(pageret.left, pageret.top,
-			SZ_1G, sizeof(struct gigapages));
-	pagearr.giga_top = (struct gigapages *)pageret.top;
-	pagearr.giga_num = pageret.num;
-
-	pageret = init_pages(pageret.left, pageret.top,
-			SZ_2M, sizeof(struct megapages));
-	pagearr.mega_top = (struct megapages *)pageret.top;
-	pagearr.mega_num = pageret.num;
-
-	pageret = init_pages(pageret.left, pageret.top,
-			SZ_4K, sizeof(struct kilopages));
-	pagearr.kilo_top = (struct kilopages *)pageret.top;
-	pagearr.kilo_num = pageret.num;
-
-	unsigned long *root_page = (unsigned long *)
-		(init_align_down((size_t)pagearr.kilo_top, SZ_4K) - SZ_4K);
-
-	unsigned long *mid_page = (unsigned long)root_page - SZ_4K;
-	unsigned long *bot_page = (unsigned long)mid_page - SZ_4K;
-
-	/* TODO: should init insert page data into the created arrays? */
-	unsigned long root_addr = (((unsigned long)boot >> 12) >> 18) & 0x1ff;
-	unsigned long mid_addr = (((unsigned long)boot >> 12) >> 9) & 0x1ff;
-	unsigned long bot_addr = (((unsigned long)boot >> 12) >> 0) & 0x1ff;
-
-	root_page[root_addr] = (((unsigned long)mid_page & ~0x3ff) >> 2) | VM_V;
-	mid_page[mid_addr] = ((unsigned long)bot_page & ~0x3ff) >> 2 | VM_V;
-	bot_page[bot_addr] = (((unsigned long)boot & ~0x3ff) >> 2) | VM_V | VM_R | VM_W | VM_X;
-
-	//root_page[0] = (((unsigned long)ram_base & ~0x3ff) >> 2) | VM_V | VM_R | VM_W | VM_X;
-
-	/* enter virtual memory */
-	init_enter_vm(root_page);
-
-	/* enter main */
-	call_main();
+	struct mem_layout pmem = get_memlayout(fdt);
+	/* struct mm_ptinfo ptbl = create_pagetable(pmem); */
 }