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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/kernel.h>
 22 #include <linux/init.h>
 23 #include <linux/clk.h>
 24 #include <linux/err.h>
 25 #include <linux/io.h>
 26 #include <linux/of.h>
 27 #include <linux/of_address.h>
 28 #include <linux/list.h>
 29 #include <linux/list_sort.h>
 30 #include <linux/platform_device.h>
 31 #include <linux/slab.h>
 32 #include <linux/spinlock.h>
 33 #include <linux/genalloc.h>
 34 
 35 #define SRAM_GRANULARITY        32
 36 
 37 struct sram_dev {
 38         struct gen_pool *pool;
 39         struct clk *clk;
 40 };
 41 
 42 struct sram_reserve {
 43         struct list_head list;
 44         u32 start;
 45         u32 size;
 46 };
 47 
 48 static int sram_reserve_cmp(void *priv, struct list_head *a,
 49                                         struct list_head *b)
 50 {
 51         struct sram_reserve *ra = list_entry(a, struct sram_reserve, list);
 52         struct sram_reserve *rb = list_entry(b, struct sram_reserve, list);
 53 
 54         return ra->start - rb->start;
 55 }
 56 
 57 static int sram_probe(struct platform_device *pdev)
 58 {
 59         void __iomem *virt_base;
 60         struct sram_dev *sram;
 61         struct resource *res;
 62         struct device_node *np = pdev->dev.of_node, *child;
 63         unsigned long size, cur_start, cur_size;
 64         struct sram_reserve *rblocks, *block;
 65         struct list_head reserve_list;
 66         unsigned int nblocks;
 67         int ret;
 68 
 69         INIT_LIST_HEAD(&reserve_list);
 70 
 71         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 72         virt_base = devm_ioremap_resource(&pdev->dev, res);
 73         if (IS_ERR(virt_base))
 74                 return PTR_ERR(virt_base);
 75 
 76         size = resource_size(res);
 77 
 78         sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
 79         if (!sram)
 80                 return -ENOMEM;
 81 
 82         sram->clk = devm_clk_get(&pdev->dev, NULL);
 83         if (IS_ERR(sram->clk))
 84                 sram->clk = NULL;
 85         else
 86                 clk_prepare_enable(sram->clk);
 87 
 88         sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -1);
 89         if (!sram->pool)
 90                 return -ENOMEM;
 91 
 92         /*
 93          * We need an additional block to mark the end of the memory region
 94          * after the reserved blocks from the dt are processed.
 95          */
 96         nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
 97         rblocks = kmalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
 98         if (!rblocks) {
 99                 ret = -ENOMEM;
100                 goto err_alloc;
101         }
102 
103         block = &rblocks[0];
104         for_each_available_child_of_node(np, child) {
105                 struct resource child_res;
106 
107                 ret = of_address_to_resource(child, 0, &child_res);
108                 if (ret < 0) {
109                         dev_err(&pdev->dev,
110                                 "could not get address for node %s\n",
111                                 child->full_name);
112                         goto err_chunks;
113                 }
114 
115                 if (child_res.start < res->start || child_res.end > res->end) {
116                         dev_err(&pdev->dev,
117                                 "reserved block %s outside the sram area\n",
118                                 child->full_name);
119                         ret = -EINVAL;
120                         goto err_chunks;
121                 }
122 
123                 block->start = child_res.start - res->start;
124                 block->size = resource_size(&child_res);
125                 list_add_tail(&block->list, &reserve_list);
126 
127                 dev_dbg(&pdev->dev, "found reserved block 0x%x-0x%x\n",
128                         block->start,
129                         block->start + block->size);
130 
131                 block++;
132         }
133 
134         /* the last chunk marks the end of the region */
135         rblocks[nblocks - 1].start = size;
136         rblocks[nblocks - 1].size = 0;
137         list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);
138 
139         list_sort(NULL, &reserve_list, sram_reserve_cmp);
140 
141         cur_start = 0;
142 
143         list_for_each_entry(block, &reserve_list, list) {
144                 /* can only happen if sections overlap */
145                 if (block->start < cur_start) {
146                         dev_err(&pdev->dev,
147                                 "block at 0x%x starts after current offset 0x%lx\n",
148                                 block->start, cur_start);
149                         ret = -EINVAL;
150                         goto err_chunks;
151                 }
152 
153                 /* current start is in a reserved block, so continue after it */
154                 if (block->start == cur_start) {
155                         cur_start = block->start + block->size;
156                         continue;
157                 }
158 
159                 /*
160                  * allocate the space between the current starting
161                  * address and the following reserved block, or the
162                  * end of the region.
163                  */
164                 cur_size = block->start - cur_start;
165 
166                 dev_dbg(&pdev->dev, "adding chunk 0x%lx-0x%lx\n",
167                         cur_start, cur_start + cur_size);
168                 ret = gen_pool_add_virt(sram->pool,
169                                 (unsigned long)virt_base + cur_start,
170                                 res->start + cur_start, cur_size, -1);
171                 if (ret < 0)
172                         goto err_chunks;
173 
174                 /* next allocation after this reserved block */
175                 cur_start = block->start + block->size;
176         }
177 
178         kfree(rblocks);
179 
180         platform_set_drvdata(pdev, sram);
181 
182         dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);
183 
184         return 0;
185 
186 err_chunks:
187         kfree(rblocks);
188 err_alloc:
189         if (sram->clk)
190                 clk_disable_unprepare(sram->clk);
191         return ret;
192 }
193 
194 static int sram_remove(struct platform_device *pdev)
195 {
196         struct sram_dev *sram = platform_get_drvdata(pdev);
197 
198         if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
199                 dev_dbg(&pdev->dev, "removed while SRAM allocated\n");
200 
201         if (sram->clk)
202                 clk_disable_unprepare(sram->clk);
203 
204         return 0;
205 }
206 
207 #ifdef CONFIG_OF
208 static struct of_device_id sram_dt_ids[] = {
209         { .compatible = "mmio-sram" },
210         {}
211 };
212 #endif
213 
214 static struct platform_driver sram_driver = {
215         .driver = {
216                 .name = "sram",
217                 .of_match_table = of_match_ptr(sram_dt_ids),
218         },
219         .probe = sram_probe,
220         .remove = sram_remove,
221 };
222 
223 static int __init sram_init(void)
224 {
225         return platform_driver_register(&sram_driver);
226 }
227 
228 postcore_initcall(sram_init);
229 

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