xref: /openbmc/linux/arch/m68k/mm/motorola.c (revision 36de991e) 
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 /* Prior to calling these routines, the page should have been flushed
49  * from both the cache and ATC, or the CPU might not notice that the
50  * cache setting for the page has been changed. -jskov
51  */
52 static inline void nocache_page(void *vaddr)
53 {
54 	unsigned long addr = (unsigned long)vaddr;
55 
56 	if (CPU_IS_040_OR_060) {
57 		pte_t *ptep = virt_to_kpte(addr);
58 
59 		*ptep = pte_mknocache(*ptep);
60 	}
61 }
62 
63 static inline void cache_page(void *vaddr)
64 {
65 	unsigned long addr = (unsigned long)vaddr;
66 
67 	if (CPU_IS_040_OR_060) {
68 		pte_t *ptep = virt_to_kpte(addr);
69 
70 		*ptep = pte_mkcache(*ptep);
71 	}
72 }
73 
74 /*
75  * Motorola 680x0 user's manual recommends using uncached memory for address
76  * translation tables.
77  *
78  * Seeing how the MMU can be external on (some of) these chips, that seems like
79  * a very important recommendation to follow. Provide some helpers to combat
80  * 'variation' amongst the users of this.
81  */
82 
83 void mmu_page_ctor(void *page)
84 {
85 	__flush_page_to_ram(page);
86 	flush_tlb_kernel_page(page);
87 	nocache_page(page);
88 }
89 
90 void mmu_page_dtor(void *page)
91 {
92 	cache_page(page);
93 }
94 
95 /* ++andreas: {get,free}_pointer_table rewritten to use unused fields from
96    struct page instead of separately kmalloced struct.  Stolen from
97    arch/sparc/mm/srmmu.c ... */
98 
99 typedef struct list_head ptable_desc;
100 
101 static struct list_head ptable_list[2] = {
102 	LIST_HEAD_INIT(ptable_list[0]),
103 	LIST_HEAD_INIT(ptable_list[1]),
104 };
105 
106 #define PD_PTABLE(page) ((ptable_desc *)&(virt_to_page(page)->lru))
107 #define PD_PAGE(ptable) (list_entry(ptable, struct page, lru))
108 #define PD_MARKBITS(dp) (*(unsigned int *)&PD_PAGE(dp)->index)
109 
110 static const int ptable_shift[2] = {
111 	7+2, /* PGD, PMD */
112 	6+2, /* PTE */
113 };
114 
115 #define ptable_size(type) (1U << ptable_shift[type])
116 #define ptable_mask(type) ((1U << (PAGE_SIZE / ptable_size(type))) - 1)
117 
118 void __init init_pointer_table(void *table, int type)
119 {
120 	ptable_desc *dp;
121 	unsigned long ptable = (unsigned long)table;
122 	unsigned long page = ptable & PAGE_MASK;
123 	unsigned int mask = 1U << ((ptable - page)/ptable_size(type));
124 
125 	dp = PD_PTABLE(page);
126 	if (!(PD_MARKBITS(dp) & mask)) {
127 		PD_MARKBITS(dp) = ptable_mask(type);
128 		list_add(dp, &ptable_list[type]);
129 	}
130 
131 	PD_MARKBITS(dp) &= ~mask;
132 	pr_debug("init_pointer_table: %lx, %x\n", ptable, PD_MARKBITS(dp));
133 
134 	/* unreserve the page so it's possible to free that page */
135 	__ClearPageReserved(PD_PAGE(dp));
136 	init_page_count(PD_PAGE(dp));
137 
138 	return;
139 }
140 
141 void *get_pointer_table(int type)
142 {
143 	ptable_desc *dp = ptable_list[type].next;
144 	unsigned int mask = list_empty(&ptable_list[type]) ? 0 : PD_MARKBITS(dp);
145 	unsigned int tmp, off;
146 
147 	/*
148 	 * For a pointer table for a user process address space, a
149 	 * table is taken from a page allocated for the purpose.  Each
150 	 * page can hold 8 pointer tables.  The page is remapped in
151 	 * virtual address space to be noncacheable.
152 	 */
153 	if (mask == 0) {
154 		void *page;
155 		ptable_desc *new;
156 
157 		if (!(page = (void *)get_zeroed_page(GFP_KERNEL)))
158 			return NULL;
159 
160 		if (type == TABLE_PTE) {
161 			/*
162 			 * m68k doesn't have SPLIT_PTE_PTLOCKS for not having
163 			 * SMP.
164 			 */
165 			pgtable_pte_page_ctor(virt_to_page(page));
166 		}
167 
168 		mmu_page_ctor(page);
169 
170 		new = PD_PTABLE(page);
171 		PD_MARKBITS(new) = ptable_mask(type) - 1;
172 		list_add_tail(new, dp);
173 
174 		return (pmd_t *)page;
175 	}
176 
177 	for (tmp = 1, off = 0; (mask & tmp) == 0; tmp <<= 1, off += ptable_size(type))
178 		;
179 	PD_MARKBITS(dp) = mask & ~tmp;
180 	if (!PD_MARKBITS(dp)) {
181 		/* move to end of list */
182 		list_move_tail(dp, &ptable_list[type]);
183 	}
184 	return page_address(PD_PAGE(dp)) + off;
185 }
186 
187 int free_pointer_table(void *table, int type)
188 {
189 	ptable_desc *dp;
190 	unsigned long ptable = (unsigned long)table;
191 	unsigned long page = ptable & PAGE_MASK;
192 	unsigned int mask = 1U << ((ptable - page)/ptable_size(type));
193 
194 	dp = PD_PTABLE(page);
195 	if (PD_MARKBITS (dp) & mask)
196 		panic ("table already free!");
197 
198 	PD_MARKBITS (dp) |= mask;
199 
200 	if (PD_MARKBITS(dp) == ptable_mask(type)) {
201 		/* all tables in page are free, free page */
202 		list_del(dp);
203 		mmu_page_dtor((void *)page);
204 		if (type == TABLE_PTE)
205 			pgtable_pte_page_dtor(virt_to_page(page));
206 		free_page (page);
207 		return 1;
208 	} else if (ptable_list[type].next != dp) {
209 		/*
210 		 * move this descriptor to the front of the list, since
211 		 * it has one or more free tables.
212 		 */
213 		list_move(dp, &ptable_list[type]);
214 	}
215 	return 0;
216 }
217 
218 /* size of memory already mapped in head.S */
219 extern __initdata unsigned long m68k_init_mapped_size;
220 
221 extern unsigned long availmem;
222 
223 static pte_t *last_pte_table __initdata = NULL;
224 
225 static pte_t * __init kernel_page_table(void)
226 {
227 	pte_t *pte_table = last_pte_table;
228 
229 	if (PAGE_ALIGNED(last_pte_table)) {
230 		pte_table = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
231 		if (!pte_table) {
232 			panic("%s: Failed to allocate %lu bytes align=%lx\n",
233 					__func__, PAGE_SIZE, PAGE_SIZE);
234 		}
235 
236 		clear_page(pte_table);
237 		mmu_page_ctor(pte_table);
238 
239 		last_pte_table = pte_table;
240 	}
241 
242 	last_pte_table += PTRS_PER_PTE;
243 
244 	return pte_table;
245 }
246 
247 static pmd_t *last_pmd_table __initdata = NULL;
248 
249 static pmd_t * __init kernel_ptr_table(void)
250 {
251 	if (!last_pmd_table) {
252 		unsigned long pmd, last;
253 		int i;
254 
255 		/* Find the last ptr table that was used in head.S and
256 		 * reuse the remaining space in that page for further
257 		 * ptr tables.
258 		 */
259 		last = (unsigned long)kernel_pg_dir;
260 		for (i = 0; i < PTRS_PER_PGD; i++) {
261 			pud_t *pud = (pud_t *)(&kernel_pg_dir[i]);
262 
263 			if (!pud_present(*pud))
264 				continue;
265 			pmd = pgd_page_vaddr(kernel_pg_dir[i]);
266 			if (pmd > last)
267 				last = pmd;
268 		}
269 
270 		last_pmd_table = (pmd_t *)last;
271 #ifdef DEBUG
272 		printk("kernel_ptr_init: %p\n", last_pmd_table);
273 #endif
274 	}
275 
276 	last_pmd_table += PTRS_PER_PMD;
277 	if (PAGE_ALIGNED(last_pmd_table)) {
278 		last_pmd_table = memblock_alloc_low(PAGE_SIZE, PAGE_SIZE);
279 		if (!last_pmd_table)
280 			panic("%s: Failed to allocate %lu bytes align=%lx\n",
281 			      __func__, PAGE_SIZE, PAGE_SIZE);
282 
283 		clear_page(last_pmd_table);
284 		mmu_page_ctor(last_pmd_table);
285 	}
286 
287 	return last_pmd_table;
288 }
289 
290 static void __init map_node(int node)
291 {
292 	unsigned long physaddr, virtaddr, size;
293 	pgd_t *pgd_dir;
294 	p4d_t *p4d_dir;
295 	pud_t *pud_dir;
296 	pmd_t *pmd_dir;
297 	pte_t *pte_dir;
298 
299 	size = m68k_memory[node].size;
300 	physaddr = m68k_memory[node].addr;
301 	virtaddr = (unsigned long)phys_to_virt(physaddr);
302 	physaddr |= m68k_supervisor_cachemode |
303 		    _PAGE_PRESENT | _PAGE_ACCESSED | _PAGE_DIRTY;
304 	if (CPU_IS_040_OR_060)
305 		physaddr |= _PAGE_GLOBAL040;
306 
307 	while (size > 0) {
308 #ifdef DEBUG
309 		if (!(virtaddr & (PMD_SIZE-1)))
310 			printk ("\npa=%#lx va=%#lx ", physaddr & PAGE_MASK,
311 				virtaddr);
312 #endif
313 		pgd_dir = pgd_offset_k(virtaddr);
314 		if (virtaddr && CPU_IS_020_OR_030) {
315 			if (!(virtaddr & (PGDIR_SIZE-1)) &&
316 			    size >= PGDIR_SIZE) {
317 #ifdef DEBUG
318 				printk ("[very early term]");
319 #endif
320 				pgd_val(*pgd_dir) = physaddr;
321 				size -= PGDIR_SIZE;
322 				virtaddr += PGDIR_SIZE;
323 				physaddr += PGDIR_SIZE;
324 				continue;
325 			}
326 		}
327 		p4d_dir = p4d_offset(pgd_dir, virtaddr);
328 		pud_dir = pud_offset(p4d_dir, virtaddr);
329 		if (!pud_present(*pud_dir)) {
330 			pmd_dir = kernel_ptr_table();
331 #ifdef DEBUG
332 			printk ("[new pointer %p]", pmd_dir);
333 #endif
334 			pud_set(pud_dir, pmd_dir);
335 		} else
336 			pmd_dir = pmd_offset(pud_dir, virtaddr);
337 
338 		if (CPU_IS_020_OR_030) {
339 			if (virtaddr) {
340 #ifdef DEBUG
341 				printk ("[early term]");
342 #endif
343 				pmd_val(*pmd_dir) = physaddr;
344 				physaddr += PMD_SIZE;
345 			} else {
346 				int i;
347 #ifdef DEBUG
348 				printk ("[zero map]");
349 #endif
350 				pte_dir = kernel_page_table();
351 				pmd_set(pmd_dir, pte_dir);
352 
353 				pte_val(*pte_dir++) = 0;
354 				physaddr += PAGE_SIZE;
355 				for (i = 1; i < PTRS_PER_PTE; physaddr += PAGE_SIZE, i++)
356 					pte_val(*pte_dir++) = physaddr;
357 			}
358 			size -= PMD_SIZE;
359 			virtaddr += PMD_SIZE;
360 		} else {
361 			if (!pmd_present(*pmd_dir)) {
362 #ifdef DEBUG
363 				printk ("[new table]");
364 #endif
365 				pte_dir = kernel_page_table();
366 				pmd_set(pmd_dir, pte_dir);
367 			}
368 			pte_dir = pte_offset_kernel(pmd_dir, virtaddr);
369 
370 			if (virtaddr) {
371 				if (!pte_present(*pte_dir))
372 					pte_val(*pte_dir) = physaddr;
373 			} else
374 				pte_val(*pte_dir) = 0;
375 			size -= PAGE_SIZE;
376 			virtaddr += PAGE_SIZE;
377 			physaddr += PAGE_SIZE;
378 		}
379 
380 	}
381 #ifdef DEBUG
382 	printk("\n");
383 #endif
384 }
385 
386 /*
387  * paging_init() continues the virtual memory environment setup which
388  * was begun by the code in arch/head.S.
389  */
390 void __init paging_init(void)
391 {
392 	unsigned long max_zone_pfn[MAX_NR_ZONES] = { 0, };
393 	unsigned long min_addr, max_addr;
394 	unsigned long addr;
395 	int i;
396 
397 #ifdef DEBUG
398 	printk ("start of paging_init (%p, %lx)\n", kernel_pg_dir, availmem);
399 #endif
400 
401 	/* Fix the cache mode in the page descriptors for the 680[46]0.  */
402 	if (CPU_IS_040_OR_060) {
403 		int i;
404 #ifndef mm_cachebits
405 		mm_cachebits = _PAGE_CACHE040;
406 #endif
407 		for (i = 0; i < 16; i++)
408 			pgprot_val(protection_map[i]) |= _PAGE_CACHE040;
409 	}
410 
411 	min_addr = m68k_memory[0].addr;
412 	max_addr = min_addr + m68k_memory[0].size;
413 	memblock_add_node(m68k_memory[0].addr, m68k_memory[0].size, 0,
414 			  MEMBLOCK_NONE);
415 	for (i = 1; i < m68k_num_memory;) {
416 		if (m68k_memory[i].addr < min_addr) {
417 			printk("Ignoring memory chunk at 0x%lx:0x%lx before the first chunk\n",
418 				m68k_memory[i].addr, m68k_memory[i].size);
419 			printk("Fix your bootloader or use a memfile to make use of this area!\n");
420 			m68k_num_memory--;
421 			memmove(m68k_memory + i, m68k_memory + i + 1,
422 				(m68k_num_memory - i) * sizeof(struct m68k_mem_info));
423 			continue;
424 		}
425 		memblock_add_node(m68k_memory[i].addr, m68k_memory[i].size, i,
426 				  MEMBLOCK_NONE);
427 		addr = m68k_memory[i].addr + m68k_memory[i].size;
428 		if (addr > max_addr)
429 			max_addr = addr;
430 		i++;
431 	}
432 	m68k_memoffset = min_addr - PAGE_OFFSET;
433 	m68k_virt_to_node_shift = fls(max_addr - min_addr - 1) - 6;
434 
435 	module_fixup(NULL, __start_fixup, __stop_fixup);
436 	flush_icache();
437 
438 	high_memory = phys_to_virt(max_addr);
439 
440 	min_low_pfn = availmem >> PAGE_SHIFT;
441 	max_pfn = max_low_pfn = max_addr >> PAGE_SHIFT;
442 
443 	/* Reserve kernel text/data/bss and the memory allocated in head.S */
444 	memblock_reserve(m68k_memory[0].addr, availmem - m68k_memory[0].addr);
445 
446 	/*
447 	 * Map the physical memory available into the kernel virtual
448 	 * address space. Make sure memblock will not try to allocate
449 	 * pages beyond the memory we already mapped in head.S
450 	 */
451 	memblock_set_bottom_up(true);
452 
453 	for (i = 0; i < m68k_num_memory; i++) {
454 		m68k_setup_node(i);
455 		map_node(i);
456 	}
457 
458 	flush_tlb_all();
459 
460 	/*
461 	 * initialize the bad page table and bad page to point
462 	 * to a couple of allocated pages
463 	 */
464 	empty_zero_page = memblock_alloc(PAGE_SIZE, PAGE_SIZE);
465 	if (!empty_zero_page)
466 		panic("%s: Failed to allocate %lu bytes align=0x%lx\n",
467 		      __func__, PAGE_SIZE, PAGE_SIZE);
468 
469 	/*
470 	 * Set up SFC/DFC registers
471 	 */
472 	set_fc(USER_DATA);
473 
474 #ifdef DEBUG
475 	printk ("before free_area_init\n");
476 #endif
477 	for (i = 0; i < m68k_num_memory; i++)
478 		if (node_present_pages(i))
479 			node_set_state(i, N_NORMAL_MEMORY);
480 
481 	max_zone_pfn[ZONE_DMA] = memblock_end_of_DRAM();
482 	free_area_init(max_zone_pfn);
483 }
484