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Linux/drivers/misc/sram.c

  1 /*
  2  * Generic on-chip SRAM allocation driver
  3  *
  4  * Copyright (C) 2012 Philipp Zabel, Pengutronix
  5  *
  6  * This program is free software; you can redistribute it and/or
  7  * modify it under the terms of the GNU General Public License
  8  * as published by the Free Software Foundation; either version 2
  9  * of the License, or (at your option) any later version.
 10  * This program is distributed in the hope that it will be useful,
 11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13  * GNU General Public License for more details.
 14  *
 15  * You should have received a copy of the GNU General Public License
 16  * along with this program; if not, write to the Free Software
 17  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
 18  * MA 02110-1301, USA.
 19  */
 20 
 21 #include <linux/clk.h>
 22 #include <linux/genalloc.h>
 23 #include <linux/io.h>
 24 #include <linux/list_sort.h>
 25 #include <linux/of_address.h>
 26 #include <linux/platform_device.h>
 27 #include <linux/slab.h>
 28 
 29 #define SRAM_GRANULARITY        32
 30 
 31 struct sram_dev {
 32         struct device *dev;
 33         void __iomem *virt_base;
 34 
 35         struct gen_pool *pool;
 36         struct clk *clk;
 37 };
 38 
 39 struct sram_reserve {
 40         struct list_head list;
 41         u32 start;
 42         u32 size;
 43 };
 44 
 45 static int sram_reserve_cmp(void *priv, struct list_head *a,
 46                                         struct list_head *b)
 47 {
 48         struct sram_reserve *ra = list_entry(a, struct sram_reserve, list);
 49         struct sram_reserve *rb = list_entry(b, struct sram_reserve, list);
 50 
 51         return ra->start - rb->start;
 52 }
 53 
 54 static int sram_reserve_regions(struct sram_dev *sram, struct resource *res)
 55 {
 56         struct device_node *np = sram->dev->of_node, *child;
 57         unsigned long size, cur_start, cur_size;
 58         struct sram_reserve *rblocks, *block;
 59         struct list_head reserve_list;
 60         unsigned int nblocks;
 61         int ret = 0;
 62 
 63         INIT_LIST_HEAD(&reserve_list);
 64 
 65         size = resource_size(res);
 66 
 67         /*
 68          * We need an additional block to mark the end of the memory region
 69          * after the reserved blocks from the dt are processed.
 70          */
 71         nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
 72         rblocks = kmalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
 73         if (!rblocks)
 74                 return -ENOMEM;
 75 
 76         block = &rblocks[0];
 77         for_each_available_child_of_node(np, child) {
 78                 struct resource child_res;
 79 
 80                 ret = of_address_to_resource(child, 0, &child_res);
 81                 if (ret < 0) {
 82                         dev_err(sram->dev,
 83                                 "could not get address for node %s\n",
 84                                 child->full_name);
 85                         of_node_put(child);
 86                         goto err_chunks;
 87                 }
 88 
 89                 if (child_res.start < res->start || child_res.end > res->end) {
 90                         dev_err(sram->dev,
 91                                 "reserved block %s outside the sram area\n",
 92                                 child->full_name);
 93                         ret = -EINVAL;
 94                         of_node_put(child);
 95                         goto err_chunks;
 96                 }
 97 
 98                 block->start = child_res.start - res->start;
 99                 block->size = resource_size(&child_res);
100                 list_add_tail(&block->list, &reserve_list);
101 
102                 dev_dbg(sram->dev, "found reserved block 0x%x-0x%x\n",
103                         block->start, block->start + block->size);
104 
105                 block++;
106         }
107 
108         /* the last chunk marks the end of the region */
109         rblocks[nblocks - 1].start = size;
110         rblocks[nblocks - 1].size = 0;
111         list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);
112 
113         list_sort(NULL, &reserve_list, sram_reserve_cmp);
114 
115         cur_start = 0;
116 
117         list_for_each_entry(block, &reserve_list, list) {
118                 /* can only happen if sections overlap */
119                 if (block->start < cur_start) {
120                         dev_err(sram->dev,
121                                 "block at 0x%x starts after current offset 0x%lx\n",
122                                 block->start, cur_start);
123                         ret = -EINVAL;
124                         goto err_chunks;
125                 }
126 
127                 /* current start is in a reserved block, so continue after it */
128                 if (block->start == cur_start) {
129                         cur_start = block->start + block->size;
130                         continue;
131                 }
132 
133                 /*
134                  * allocate the space between the current starting
135                  * address and the following reserved block, or the
136                  * end of the region.
137                  */
138                 cur_size = block->start - cur_start;
139 
140                 dev_dbg(sram->dev, "adding chunk 0x%lx-0x%lx\n",
141                         cur_start, cur_start + cur_size);
142 
143                 ret = gen_pool_add_virt(sram->pool,
144                                 (unsigned long)sram->virt_base + cur_start,
145                                 res->start + cur_start, cur_size, -1);
146                 if (ret < 0)
147                         goto err_chunks;
148 
149                 /* next allocation after this reserved block */
150                 cur_start = block->start + block->size;
151         }
152 
153  err_chunks:
154         kfree(rblocks);
155 
156         return ret;
157 }
158 
159 static int sram_probe(struct platform_device *pdev)
160 {
161         struct sram_dev *sram;
162         struct resource *res;
163         size_t size;
164         int ret;
165 
166         sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
167         if (!sram)
168                 return -ENOMEM;
169 
170         sram->dev = &pdev->dev;
171 
172         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
173         if (!res) {
174                 dev_err(sram->dev, "found no memory resource\n");
175                 return -EINVAL;
176         }
177 
178         size = resource_size(res);
179 
180         if (!devm_request_mem_region(sram->dev, res->start, size, pdev->name)) {
181                 dev_err(sram->dev, "could not request region for resource\n");
182                 return -EBUSY;
183         }
184 
185         sram->virt_base = devm_ioremap_wc(sram->dev, res->start, size);
186         if (IS_ERR(sram->virt_base))
187                 return PTR_ERR(sram->virt_base);
188 
189         sram->pool = devm_gen_pool_create(sram->dev,
190                                           ilog2(SRAM_GRANULARITY), -1);
191         if (!sram->pool)
192                 return -ENOMEM;
193 
194         ret = sram_reserve_regions(sram, res);
195         if (ret)
196                 return ret;
197 
198         sram->clk = devm_clk_get(sram->dev, NULL);
199         if (IS_ERR(sram->clk))
200                 sram->clk = NULL;
201         else
202                 clk_prepare_enable(sram->clk);
203 
204         platform_set_drvdata(pdev, sram);
205 
206         dev_dbg(sram->dev, "SRAM pool: %zu KiB @ 0x%p\n",
207                 gen_pool_size(sram->pool) / 1024, sram->virt_base);
208 
209         return 0;
210 }
211 
212 static int sram_remove(struct platform_device *pdev)
213 {
214         struct sram_dev *sram = platform_get_drvdata(pdev);
215 
216         if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
217                 dev_err(sram->dev, "removed while SRAM allocated\n");
218 
219         if (sram->clk)
220                 clk_disable_unprepare(sram->clk);
221 
222         return 0;
223 }
224 
225 #ifdef CONFIG_OF
226 static const struct of_device_id sram_dt_ids[] = {
227         { .compatible = "mmio-sram" },
228         {}
229 };
230 #endif
231 
232 static struct platform_driver sram_driver = {
233         .driver = {
234                 .name = "sram",
235                 .of_match_table = of_match_ptr(sram_dt_ids),
236         },
237         .probe = sram_probe,
238         .remove = sram_remove,
239 };
240 
241 static int __init sram_init(void)
242 {
243         return platform_driver_register(&sram_driver);
244 }
245 
246 postcore_initcall(sram_init);
247 

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