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, ilog2(SRAM_GRANULARITY),
 190                                           NUMA_NO_NODE, NULL);
 191         if (IS_ERR(sram->pool))
 192                 return PTR_ERR(sram->pool);
 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);