1/*
2 * Register cache access API - LZO caching support
3 *
4 * Copyright 2011 Wolfson Microelectronics plc
5 *
6 * Author: Dimitris Papastamos <dp@opensource.wolfsonmicro.com>
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 */
12
13#include <linux/slab.h>
14#include <linux/device.h>
15#include <linux/lzo.h>
16
17#include "internal.h"
18
19static int regcache_lzo_exit(struct regmap *map);
20
21struct regcache_lzo_ctx {
22	void *wmem;
23	void *dst;
24	const void *src;
25	size_t src_len;
26	size_t dst_len;
27	size_t decompressed_size;
28	unsigned long *sync_bmp;
29	int sync_bmp_nbits;
30};
31
32#define LZO_BLOCK_NUM 8
33static int regcache_lzo_block_count(struct regmap *map)
34{
35	return LZO_BLOCK_NUM;
36}
37
38static int regcache_lzo_prepare(struct regcache_lzo_ctx *lzo_ctx)
39{
40	lzo_ctx->wmem = kmalloc(LZO1X_MEM_COMPRESS, GFP_KERNEL);
41	if (!lzo_ctx->wmem)
42		return -ENOMEM;
43	return 0;
44}
45
46static int regcache_lzo_compress(struct regcache_lzo_ctx *lzo_ctx)
47{
48	size_t compress_size;
49	int ret;
50
51	ret = lzo1x_1_compress(lzo_ctx->src, lzo_ctx->src_len,
52			       lzo_ctx->dst, &compress_size, lzo_ctx->wmem);
53	if (ret != LZO_E_OK || compress_size > lzo_ctx->dst_len)
54		return -EINVAL;
55	lzo_ctx->dst_len = compress_size;
56	return 0;
57}
58
59static int regcache_lzo_decompress(struct regcache_lzo_ctx *lzo_ctx)
60{
61	size_t dst_len;
62	int ret;
63
64	dst_len = lzo_ctx->dst_len;
65	ret = lzo1x_decompress_safe(lzo_ctx->src, lzo_ctx->src_len,
66				    lzo_ctx->dst, &dst_len);
67	if (ret != LZO_E_OK || dst_len != lzo_ctx->dst_len)
68		return -EINVAL;
69	return 0;
70}
71
72static int regcache_lzo_compress_cache_block(struct regmap *map,
73		struct regcache_lzo_ctx *lzo_ctx)
74{
75	int ret;
76
77	lzo_ctx->dst_len = lzo1x_worst_compress(PAGE_SIZE);
78	lzo_ctx->dst = kmalloc(lzo_ctx->dst_len, GFP_KERNEL);
79	if (!lzo_ctx->dst) {
80		lzo_ctx->dst_len = 0;
81		return -ENOMEM;
82	}
83
84	ret = regcache_lzo_compress(lzo_ctx);
85	if (ret < 0)
86		return ret;
87	return 0;
88}
89
90static int regcache_lzo_decompress_cache_block(struct regmap *map,
91		struct regcache_lzo_ctx *lzo_ctx)
92{
93	int ret;
94
95	lzo_ctx->dst_len = lzo_ctx->decompressed_size;
96	lzo_ctx->dst = kmalloc(lzo_ctx->dst_len, GFP_KERNEL);
97	if (!lzo_ctx->dst) {
98		lzo_ctx->dst_len = 0;
99		return -ENOMEM;
100	}
101
102	ret = regcache_lzo_decompress(lzo_ctx);
103	if (ret < 0)
104		return ret;
105	return 0;
106}
107
108static inline int regcache_lzo_get_blkindex(struct regmap *map,
109					    unsigned int reg)
110{
111	return (reg * map->cache_word_size) /
112		DIV_ROUND_UP(map->cache_size_raw,
113			     regcache_lzo_block_count(map));
114}
115
116static inline int regcache_lzo_get_blkpos(struct regmap *map,
117					  unsigned int reg)
118{
119	return reg % (DIV_ROUND_UP(map->cache_size_raw,
120				   regcache_lzo_block_count(map)) /
121		      map->cache_word_size);
122}
123
124static inline int regcache_lzo_get_blksize(struct regmap *map)
125{
126	return DIV_ROUND_UP(map->cache_size_raw,
127			    regcache_lzo_block_count(map));
128}
129
130static int regcache_lzo_init(struct regmap *map)
131{
132	struct regcache_lzo_ctx **lzo_blocks;
133	size_t bmp_size;
134	int ret, i, blksize, blkcount;
135	const char *p, *end;
136	unsigned long *sync_bmp;
137
138	ret = 0;
139
140	blkcount = regcache_lzo_block_count(map);
141	map->cache = kzalloc(blkcount * sizeof *lzo_blocks,
142			     GFP_KERNEL);
143	if (!map->cache)
144		return -ENOMEM;
145	lzo_blocks = map->cache;
146
147	/*
148	 * allocate a bitmap to be used when syncing the cache with
149	 * the hardware.  Each time a register is modified, the corresponding
150	 * bit is set in the bitmap, so we know that we have to sync
151	 * that register.
152	 */
153	bmp_size = map->num_reg_defaults_raw;
154	sync_bmp = kmalloc(BITS_TO_LONGS(bmp_size) * sizeof(long),
155			   GFP_KERNEL);
156	if (!sync_bmp) {
157		ret = -ENOMEM;
158		goto err;
159	}
160	bitmap_zero(sync_bmp, bmp_size);
161
162	/* allocate the lzo blocks and initialize them */
163	for (i = 0; i < blkcount; i++) {
164		lzo_blocks[i] = kzalloc(sizeof **lzo_blocks,
165					GFP_KERNEL);
166		if (!lzo_blocks[i]) {
167			kfree(sync_bmp);
168			ret = -ENOMEM;
169			goto err;
170		}
171		lzo_blocks[i]->sync_bmp = sync_bmp;
172		lzo_blocks[i]->sync_bmp_nbits = bmp_size;
173		/* alloc the working space for the compressed block */
174		ret = regcache_lzo_prepare(lzo_blocks[i]);
175		if (ret < 0)
176			goto err;
177	}
178
179	blksize = regcache_lzo_get_blksize(map);
180	p = map->reg_defaults_raw;
181	end = map->reg_defaults_raw + map->cache_size_raw;
182	/* compress the register map and fill the lzo blocks */
183	for (i = 0; i < blkcount; i++, p += blksize) {
184		lzo_blocks[i]->src = p;
185		if (p + blksize > end)
186			lzo_blocks[i]->src_len = end - p;
187		else
188			lzo_blocks[i]->src_len = blksize;
189		ret = regcache_lzo_compress_cache_block(map,
190						       lzo_blocks[i]);
191		if (ret < 0)
192			goto err;
193		lzo_blocks[i]->decompressed_size =
194			lzo_blocks[i]->src_len;
195	}
196
197	return 0;
198err:
199	regcache_lzo_exit(map);
200	return ret;
201}
202
203static int regcache_lzo_exit(struct regmap *map)
204{
205	struct regcache_lzo_ctx **lzo_blocks;
206	int i, blkcount;
207
208	lzo_blocks = map->cache;
209	if (!lzo_blocks)
210		return 0;
211
212	blkcount = regcache_lzo_block_count(map);
213	/*
214	 * the pointer to the bitmap used for syncing the cache
215	 * is shared amongst all lzo_blocks.  Ensure it is freed
216	 * only once.
217	 */
218	if (lzo_blocks[0])
219		kfree(lzo_blocks[0]->sync_bmp);
220	for (i = 0; i < blkcount; i++) {
221		if (lzo_blocks[i]) {
222			kfree(lzo_blocks[i]->wmem);
223			kfree(lzo_blocks[i]->dst);
224		}
225		/* each lzo_block is a pointer returned by kmalloc or NULL */
226		kfree(lzo_blocks[i]);
227	}
228	kfree(lzo_blocks);
229	map->cache = NULL;
230	return 0;
231}
232
233static int regcache_lzo_read(struct regmap *map,
234			     unsigned int reg, unsigned int *value)
235{
236	struct regcache_lzo_ctx *lzo_block, **lzo_blocks;
237	int ret, blkindex, blkpos;
238	size_t blksize, tmp_dst_len;
239	void *tmp_dst;
240
241	/* index of the compressed lzo block */
242	blkindex = regcache_lzo_get_blkindex(map, reg);
243	/* register index within the decompressed block */
244	blkpos = regcache_lzo_get_blkpos(map, reg);
245	/* size of the compressed block */
246	blksize = regcache_lzo_get_blksize(map);
247	lzo_blocks = map->cache;
248	lzo_block = lzo_blocks[blkindex];
249
250	/* save the pointer and length of the compressed block */
251	tmp_dst = lzo_block->dst;
252	tmp_dst_len = lzo_block->dst_len;
253
254	/* prepare the source to be the compressed block */
255	lzo_block->src = lzo_block->dst;
256	lzo_block->src_len = lzo_block->dst_len;
257
258	/* decompress the block */
259	ret = regcache_lzo_decompress_cache_block(map, lzo_block);
260	if (ret >= 0)
261		/* fetch the value from the cache */
262		*value = regcache_get_val(lzo_block->dst, blkpos,
263					  map->cache_word_size);
264
265	kfree(lzo_block->dst);
266	/* restore the pointer and length of the compressed block */
267	lzo_block->dst = tmp_dst;
268	lzo_block->dst_len = tmp_dst_len;
269
270	return ret;
271}
272
273static int regcache_lzo_write(struct regmap *map,
274			      unsigned int reg, unsigned int value)
275{
276	struct regcache_lzo_ctx *lzo_block, **lzo_blocks;
277	int ret, blkindex, blkpos;
278	size_t blksize, tmp_dst_len;
279	void *tmp_dst;
280
281	/* index of the compressed lzo block */
282	blkindex = regcache_lzo_get_blkindex(map, reg);
283	/* register index within the decompressed block */
284	blkpos = regcache_lzo_get_blkpos(map, reg);
285	/* size of the compressed block */
286	blksize = regcache_lzo_get_blksize(map);
287	lzo_blocks = map->cache;
288	lzo_block = lzo_blocks[blkindex];
289
290	/* save the pointer and length of the compressed block */
291	tmp_dst = lzo_block->dst;
292	tmp_dst_len = lzo_block->dst_len;
293
294	/* prepare the source to be the compressed block */
295	lzo_block->src = lzo_block->dst;
296	lzo_block->src_len = lzo_block->dst_len;
297
298	/* decompress the block */
299	ret = regcache_lzo_decompress_cache_block(map, lzo_block);
300	if (ret < 0) {
301		kfree(lzo_block->dst);
302		goto out;
303	}
304
305	/* write the new value to the cache */
306	if (regcache_set_val(lzo_block->dst, blkpos, value,
307			     map->cache_word_size)) {
308		kfree(lzo_block->dst);
309		goto out;
310	}
311
312	/* prepare the source to be the decompressed block */
313	lzo_block->src = lzo_block->dst;
314	lzo_block->src_len = lzo_block->dst_len;
315
316	/* compress the block */
317	ret = regcache_lzo_compress_cache_block(map, lzo_block);
318	if (ret < 0) {
319		kfree(lzo_block->dst);
320		kfree(lzo_block->src);
321		goto out;
322	}
323
324	/* set the bit so we know we have to sync this register */
325	set_bit(reg, lzo_block->sync_bmp);
326	kfree(tmp_dst);
327	kfree(lzo_block->src);
328	return 0;
329out:
330	lzo_block->dst = tmp_dst;
331	lzo_block->dst_len = tmp_dst_len;
332	return ret;
333}
334
335static int regcache_lzo_sync(struct regmap *map, unsigned int min,
336			     unsigned int max)
337{
338	struct regcache_lzo_ctx **lzo_blocks;
339	unsigned int val;
340	int i;
341	int ret;
342
343	lzo_blocks = map->cache;
344	i = min;
345	for_each_set_bit_from(i, lzo_blocks[0]->sync_bmp,
346			      lzo_blocks[0]->sync_bmp_nbits) {
347		if (i > max)
348			continue;
349
350		ret = regcache_read(map, i, &val);
351		if (ret)
352			return ret;
353
354		/* Is this the hardware default?  If so skip. */
355		ret = regcache_lookup_reg(map, i);
356		if (ret > 0 && val == map->reg_defaults[ret].def)
357			continue;
358
359		map->cache_bypass = 1;
360		ret = _regmap_write(map, i, val);
361		map->cache_bypass = 0;
362		if (ret)
363			return ret;
364		dev_dbg(map->dev, "Synced register %#x, value %#x\n",
365			i, val);
366	}
367
368	return 0;
369}
370
371struct regcache_ops regcache_lzo_ops = {
372	.type = REGCACHE_COMPRESSED,
373	.name = "lzo",
374	.init = regcache_lzo_init,
375	.exit = regcache_lzo_exit,
376	.read = regcache_lzo_read,
377	.write = regcache_lzo_write,
378	.sync = regcache_lzo_sync
379};
380