xref: /openbmc/linux/arch/m68k/mm/motorola.c (revision 337cbeb2)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * linux/arch/m68k/mm/motorola.c
4  *
5  * Routines specific to the Motorola MMU, originally from:
6  * linux/arch/m68k/init.c
7  * which are Copyright (C) 1995 Hamish Macdonald
8  *
9  * Moved 8/20/1999 Sam Creasey
10  */
11 
12 #include <linux/module.h>
13 #include <linux/signal.h>
14 #include <linux/sched.h>
15 #include <linux/mm.h>
16 #include <linux/swap.h>
17 #include <linux/kernel.h>
18 #include <linux/string.h>
19 #include <linux/types.h>
20 #include <linux/init.h>
21 #include <linux/memblock.h>
22 #include <linux/gfp.h>
23 
24 #include <asm/setup.h>
25 #include <linux/uaccess.h>
26 #include <asm/page.h>
27 #include <asm/pgalloc.h>
28 #include <asm/machdep.h>
29 #include <asm/io.h>
30 #include <asm/dma.h>
31 #ifdef CONFIG_ATARI
32 #include <asm/atari_stram.h>
33 #endif
34 #include <asm/sections.h>
35 
36 #undef DEBUG
37 
38 #ifndef mm_cachebits
39 /*
40  * Bits to add to page descriptors for "normal" caching mode.
41  * For 68020/030 this is 0.
42  * For 68040, this is _PAGE_CACHE040 (cachable, copyback)
43  */
44 unsigned long mm_cachebits;
45 EXPORT_SYMBOL(mm_cachebits);
46 #endif
47 
48 
49 /*
50  * Motorola 680x0 user's manual recommends using uncached memory for address
51  * translation tables.
52  *
53  * Seeing how the MMU can be external on (some of) these chips, that seems like
54  * a very important recommendation to follow. Provide some helpers to combat
55  * 'variation' amongst the users of this.
56  */
57 
58 void mmu_page_ctor(void *page)
59 {
60 	__flush_page_to_ram(page);
61 	flush_tlb_kernel_page(page);
62 	nocache_page(page);
63 }
64 
65 void mmu_page_dtor(void *page)
66 {
67 	cache_page(page);
68 }
69 
70 /* ++andreas: {get,free}_pointer_table rewritten to use unused fields from
71    struct page instead of separately kmalloced struct.  Stolen from
72    arch/sparc/mm/srmmu.c ... */
73 
74 typedef struct list_head ptable_desc;
75 
76 static struct list_head ptable_list[2] = {
77 	LIST_HEAD_INIT(ptable_list[0]),
78 	LIST_HEAD_INIT(ptable_list[1]),
79 };
80 
81 #define PD_PTABLE(page) ((ptable_desc *)&(virt_to_page(page)->lru))
82 #define PD_PAGE(ptable) (list_entry(ptable, struct page, lru))
83 #define PD_MARKBITS(dp) (*(unsigned int *)&PD_PAGE(dp)->index)
84 
85 static const int ptable_shift[2] = {
86 	7+2, /* PGD, PMD */
87 	6+2, /* PTE */
88 };
89 
90 #define ptable_size(type) (1U << ptable_shift[type])
91 #define ptable_mask(type) ((1U << (PAGE_SIZE / ptable_size(type))) - 1)
92 
93 void __init init_pointer_table(void *table, int type)
94 {
95 	ptable_desc *dp;
96 	unsigned long ptable = (unsigned long)table;
97 	unsigned long page = ptable & PAGE_MASK;
98 	unsigned int mask = 1U << ((ptable - page)/ptable_size(type));
99 
100 	dp = PD_PTABLE(page);
101 	if (!(PD_MARKBITS(dp) & mask)) {
102 		PD_MARKBITS(dp) = ptable_mask(type);
103 		list_add(dp, &ptable_list[type]);
104 	}
105 
106 	PD_MARKBITS(dp) &= ~mask;
107 	pr_debug("init_pointer_table: %lx, %x\n", ptable, PD_MARKBITS(dp));
108 
109 	/* unreserve the page so it's possible to free that page */
110 	__ClearPageReserved(PD_PAGE(dp));
111 	init_page_count(PD_PAGE(dp));
112 
113 	return;
114 }
115 
116 void *get_pointer_table(int type)
117 {
118 	ptable_desc *dp = ptable_list[type].next;
119 	unsigned int mask = list_empty(&ptable_list[type]) ? 0 : PD_MARKBITS(dp);
120 	unsigned int tmp, off;
121 
122 	/*
123 	 * For a pointer table for a user process address space, a
124 	 * table is taken from a page allocated for the purpose.  Each
125 	 * page can hold 8 pointer tables.  The page is remapped in
126 	 * virtual address space to be noncacheable.
127 	 */
128 	if (mask == 0) {
129 		void *page;
130 		ptable_desc *new;
131 
132 		if (!(page = (void *)get_zeroed_page(GFP_KERNEL)))
133 			return NULL;
134 
135 		if (type == TABLE_PTE) {
136 			/*
137 			 * m68k doesn't have SPLIT_PTE_PTLOCKS for not having
138 			 * SMP.
139 			 */
140 			pgtable_pte_page_ctor(virt_to_page(page));
141 		}
142 
143 		mmu_page_ctor(page);
144 
145 		new = PD_PTABLE(page);
146 		PD_MARKBITS(new) = ptable_mask(type) - 1;
147 		list_add_tail(new, dp);
148 
149 		return (pmd_t *)page;
150 	}
151 
152 	for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += ptable_size(type))
153 		;
154 	PD_MARKBITS(dp) = mask & ~tmp;
155 	if (!PD_MARKBITS(dp)) {
156 		/* move to end of list */
157 		list_move_tail(dp, &ptable_list[type]);
158 	}
159 	return page_address(PD_PAGE(dp)) + off;
160 }
161 
162 int free_pointer_table(void *table, int type)
163 {
164 	ptable_desc *dp;
165 	unsigned long ptable = (unsigned long)table;
166 	unsigned long page = ptable & PAGE_MASK;
167 	unsigned int mask = 1U << ((ptable - page)/ptable_size(type));
168 
169 	dp = PD_PTABLE(page);
170 	if (PD_MARKBITS (dp) & mask)
171 		panic ("table already free!");
172 
173 	PD_MARKBITS (dp) |= mask;
174 
175 	if (PD_MARKBITS(dp) == ptable_mask(type)) {
176 		/* all tables in page are free, free page */
177 		list_del(dp);
178 		mmu_page_dtor((void *)page);
179 		if (type == TABLE_PTE)
180 			pgtable_pte_page_dtor(virt_to_page(page));
181 		free_page (page);
182 		return 1;
183 	} else if (ptable_list[type].next != dp) {
184 		/*
185 		 * move this descriptor to the front of the list, since
186 		 * it has one or more free tables.
187 		 */
188 		list_move(dp, &ptable_list[type]);
189 	}
190 	return 0;
191 }
192 
193 /* size of memory already mapped in head.S */
194 extern __initdata unsigned long m68k_init_mapped_size;
195 
196 extern unsigned long availmem;
197 
198 static pte_t *last_pte_table __initdata = NULL;
199 
200 static pte_t * __init kernel_page_table(void)
201 {
202 	pte_t *pte_table = last_pte_table;
203 
204 	if (((unsigned long)last_pte_table & ~PAGE_MASK) == 0) {
205 		pte_table = (pte_t *)memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
206 		if (!pte_table) {
207 			panic("%s: Failed to allocate %lu bytes align=%lx\n",
208 					__func__, PAGE_SIZE, PAGE_SIZE);
209 		}
210 
211 		clear_page(pte_table);
212 		mmu_page_ctor(pte_table);
213 
214 		last_pte_table = pte_table;
215 	}
216 
217 	last_pte_table += PTRS_PER_PTE;
218 
219 	return pte_table;
220 }
221 
222 static pmd_t *last_pmd_table __initdata = NULL;
223 
224 static pmd_t * __init kernel_ptr_table(void)
225 {
226 	if (!last_pmd_table) {
227 		unsigned long pmd, last;
228 		int i;
229 
230 		/* Find the last ptr table that was used in head.S and
231 		 * reuse the remaining space in that page for further
232 		 * ptr tables.
233 		 */
234 		last = (unsigned long)kernel_pg_dir;
235 		for (i = 0; i < PTRS_PER_PGD; i++) {
236 			pud_t *pud = (pud_t *)(&kernel_pg_dir[i]);
237 
238 			if (!pud_present(*pud))
239 				continue;
240 			pmd = pgd_page_vaddr(kernel_pg_dir[i]);
241 			if (pmd > last)
242 				last = pmd;
243 		}
244 
245 		last_pmd_table = (pmd_t *)last;
246 #ifdef DEBUG
247 		printk("kernel_ptr_init: %p\n", last_pmd_table);
248 #endif
249 	}
250 
251 	last_pmd_table += PTRS_PER_PMD;
252 	if (((unsigned long)last_pmd_table & ~PAGE_MASK) == 0) {
253 		last_pmd_table = (pmd_t *)memblock_alloc_low(PAGE_SIZE,
254 							   PAGE_SIZE);
255 		if (!last_pmd_table)
256 			panic("%s: Failed to allocate %lu bytes align=%lx\n",
257 			      __func__, PAGE_SIZE, PAGE_SIZE);
258 
259 		clear_page(last_pmd_table);
260 		mmu_page_ctor(last_pmd_table);
261 	}
262 
263 	return last_pmd_table;
264 }
265 
266 static void __init map_node(int node)
267 {
268 	unsigned long physaddr, virtaddr, size;
269 	pgd_t *pgd_dir;
270 	p4d_t *p4d_dir;
271 	pud_t *pud_dir;
272 	pmd_t *pmd_dir;
273 	pte_t *pte_dir;
274 
275 	size = m68k_memory[node].size;
276 	physaddr = m68k_memory[node].addr;
277 	virtaddr = (unsigned long)phys_to_virt(physaddr);
278 	physaddr |= m68k_supervisor_cachemode |
279 		    _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY;
280 	if (CPU_IS_040_OR_060)
281 		physaddr |= _PAGE_GLOBAL040;
282 
283 	while (size > 0) {
284 #ifdef DEBUG
285 		if (!(virtaddr & (PMD_SIZE-1)))
286 			printk ("\npa=%#lx va=%#lx ", physaddr & PAGE_MASK,
287 				virtaddr);
288 #endif
289 		pgd_dir = pgd_offset_k(virtaddr);
290 		if (virtaddr && CPU_IS_020_OR_030) {
291 			if (!(virtaddr & (PGDIR_SIZE-1)) &&
292 			    size >= PGDIR_SIZE) {
293 #ifdef DEBUG
294 				printk ("[very early term]");
295 #endif
296 				pgd_val(*pgd_dir) = physaddr;
297 				size -= PGDIR_SIZE;
298 				virtaddr += PGDIR_SIZE;
299 				physaddr += PGDIR_SIZE;
300 				continue;
301 			}
302 		}
303 		p4d_dir = p4d_offset(pgd_dir, virtaddr);
304 		pud_dir = pud_offset(p4d_dir, virtaddr);
305 		if (!pud_present(*pud_dir)) {
306 			pmd_dir = kernel_ptr_table();
307 #ifdef DEBUG
308 			printk ("[new pointer %p]", pmd_dir);
309 #endif
310 			pud_set(pud_dir, pmd_dir);
311 		} else
312 			pmd_dir = pmd_offset(pud_dir, virtaddr);
313 
314 		if (CPU_IS_020_OR_030) {
315 			if (virtaddr) {
316 #ifdef DEBUG
317 				printk ("[early term]");
318 #endif
319 				pmd_val(*pmd_dir) = physaddr;
320 				physaddr += PMD_SIZE;
321 			} else {
322 				int i;
323 #ifdef DEBUG
324 				printk ("[zero map]");
325 #endif
326 				pte_dir = kernel_page_table();
327 				pmd_set(pmd_dir, pte_dir);
328 
329 				pte_val(*pte_dir++) = 0;
330 				physaddr += PAGE_SIZE;
331 				for (i = 1; i < PTRS_PER_PTE; physaddr += PAGE_SIZE, i++)
332 					pte_val(*pte_dir++) = physaddr;
333 			}
334 			size -= PMD_SIZE;
335 			virtaddr += PMD_SIZE;
336 		} else {
337 			if (!pmd_present(*pmd_dir)) {
338 #ifdef DEBUG
339 				printk ("[new table]");
340 #endif
341 				pte_dir = kernel_page_table();
342 				pmd_set(pmd_dir, pte_dir);
343 			}
344 			pte_dir = pte_offset_kernel(pmd_dir, virtaddr);
345 
346 			if (virtaddr) {
347 				if (!pte_present(*pte_dir))
348 					pte_val(*pte_dir) = physaddr;
349 			} else
350 				pte_val(*pte_dir) = 0;
351 			size -= PAGE_SIZE;
352 			virtaddr += PAGE_SIZE;
353 			physaddr += PAGE_SIZE;
354 		}
355 
356 	}
357 #ifdef DEBUG
358 	printk("\n");
359 #endif
360 }
361 
362 /*
363  * paging_init() continues the virtual memory environment setup which
364  * was begun by the code in arch/head.S.
365  */
366 void __init paging_init(void)
367 {
368 	unsigned long zones_size[MAX_NR_ZONES] = { 0, };
369 	unsigned long min_addr, max_addr;
370 	unsigned long addr;
371 	int i;
372 
373 #ifdef DEBUG
374 	printk ("start of paging_init (%p, %lx)\n", kernel_pg_dir, availmem);
375 #endif
376 
377 	/* Fix the cache mode in the page descriptors for the 680[46]0.  */
378 	if (CPU_IS_040_OR_060) {
379 		int i;
380 #ifndef mm_cachebits
381 		mm_cachebits = _PAGE_CACHE040;
382 #endif
383 		for (i = 0; i < 16; i++)
384 			pgprot_val(protection_map[i]) |= _PAGE_CACHE040;
385 	}
386 
387 	min_addr = m68k_memory[0].addr;
388 	max_addr = min_addr + m68k_memory[0].size;
389 	memblock_add(m68k_memory[0].addr, m68k_memory[0].size);
390 	for (i = 1; i < m68k_num_memory;) {
391 		if (m68k_memory[i].addr < min_addr) {
392 			printk("Ignoring memory chunk at 0x%lx:0x%lx before the first chunk\n",
393 				m68k_memory[i].addr, m68k_memory[i].size);
394 			printk("Fix your bootloader or use a memfile to make use of this area!\n");
395 			m68k_num_memory--;
396 			memmove(m68k_memory + i, m68k_memory + i + 1,
397 				(m68k_num_memory - i) * sizeof(struct m68k_mem_info));
398 			continue;
399 		}
400 		memblock_add(m68k_memory[i].addr, m68k_memory[i].size);
401 		addr = m68k_memory[i].addr + m68k_memory[i].size;
402 		if (addr > max_addr)
403 			max_addr = addr;
404 		i++;
405 	}
406 	m68k_memoffset = min_addr - PAGE_OFFSET;
407 	m68k_virt_to_node_shift = fls(max_addr - min_addr - 1) - 6;
408 
409 	module_fixup(NULL, __start_fixup, __stop_fixup);
410 	flush_icache();
411 
412 	high_memory = phys_to_virt(max_addr);
413 
414 	min_low_pfn = availmem >> PAGE_SHIFT;
415 	max_pfn = max_low_pfn = max_addr >> PAGE_SHIFT;
416 
417 	/* Reserve kernel text/data/bss and the memory allocated in head.S */
418 	memblock_reserve(m68k_memory[0].addr, availmem - m68k_memory[0].addr);
419 
420 	/*
421 	 * Map the physical memory available into the kernel virtual
422 	 * address space. Make sure memblock will not try to allocate
423 	 * pages beyond the memory we already mapped in head.S
424 	 */
425 	memblock_set_bottom_up(true);
426 
427 	for (i = 0; i < m68k_num_memory; i++) {
428 		m68k_setup_node(i);
429 		map_node(i);
430 	}
431 
432 	flush_tlb_all();
433 
434 	/*
435 	 * initialize the bad page table and bad page to point
436 	 * to a couple of allocated pages
437 	 */
438 	empty_zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
439 	if (!empty_zero_page)
440 		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
441 		      __func__, PAGE_SIZE, PAGE_SIZE);
442 
443 	/*
444 	 * Set up SFC/DFC registers
445 	 */
446 	set_fs(KERNEL_DS);
447 
448 #ifdef DEBUG
449 	printk ("before free_area_init\n");
450 #endif
451 	for (i = 0; i < m68k_num_memory; i++) {
452 		zones_size[ZONE_DMA] = m68k_memory[i].size >> PAGE_SHIFT;
453 		free_area_init_node(i, zones_size,
454 				    m68k_memory[i].addr >> PAGE_SHIFT, NULL);
455 		if (node_present_pages(i))
456 			node_set_state(i, N_NORMAL_MEMORY);
457 	}
458 }
459