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         if (!res) {
  73                 dev_err(&pdev->dev, "found no memory resource\n");
  74                 return -EINVAL;
  75         }
  76
  77         size = resource_size(res);
  78
  79         if (!devm_request_mem_region(&pdev->dev,
  80                         res->start, size, pdev->name)) {
  81                 dev_err(&pdev->dev, "could not request region for resource\n");
  82                 return -EBUSY;
  83         }
  84
  85         virt_base = devm_ioremap_wc(&pdev->dev, res->start, size);
  86         if (IS_ERR(virt_base))
  87                 return PTR_ERR(virt_base);
  88
  89         sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
  90         if (!sram)
  91                 return -ENOMEM;
  92
  93         sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -1);
  94         if (!sram->pool)
  95                 return -ENOMEM;
  96
  97         /*
  98          * We need an additional block to mark the end of the memory region
  99          * after the reserved blocks from the dt are processed.
 100          */
 101         nblocks = (np) ? of_get_available_child_count(np) + 1 : 1;
 102         rblocks = kmalloc((nblocks) * sizeof(*rblocks), GFP_KERNEL);
 103         if (!rblocks)
 104                 return -ENOMEM;
 105
 106         block = &rblocks[0];
 107         for_each_available_child_of_node(np, child) {
 108                 struct resource child_res;
 109
 110                 ret = of_address_to_resource(child, 0, &child_res);
 111                 if (ret < 0) {
 112                         dev_err(&pdev->dev,
 113                                 "could not get address for node %s\n",
 114                                 child->full_name);
 115                         of_node_put(child);
 116                         goto err_chunks;
 117                 }
 118
 119                 if (child_res.start < res->start || child_res.end > res->end) {
 120                         dev_err(&pdev->dev,
 121                                 "reserved block %s outside the sram area\n",
 122                                 child->full_name);
 123                         ret = -EINVAL;
 124                         of_node_put(child);
 125                         goto err_chunks;
 126                 }
 127
 128                 block->start = child_res.start - res->start;
 129                 block->size = resource_size(&child_res);
 130                 list_add_tail(&block->list, &reserve_list);
 131
 132                 dev_dbg(&pdev->dev, "found reserved block 0x%x-0x%x\n",
 133                         block->start,
 134                         block->start + block->size);
 135
 136                 block++;
 137         }
 138
 139         /* the last chunk marks the end of the region */
 140         rblocks[nblocks - 1].start = size;
 141         rblocks[nblocks - 1].size = 0;
 142         list_add_tail(&rblocks[nblocks - 1].list, &reserve_list);
 143
 144         list_sort(NULL, &reserve_list, sram_reserve_cmp);
 145
 146         cur_start = 0;
 147
 148         list_for_each_entry(block, &reserve_list, list) {
 149                 /* can only happen if sections overlap */
 150                 if (block->start < cur_start) {
 151                         dev_err(&pdev->dev,
 152                                 "block at 0x%x starts after current offset 0x%lx\n",
 153                                 block->start, cur_start);
 154                         ret = -EINVAL;
 155                         goto err_chunks;
 156                 }
 157
 158                 /* current start is in a reserved block, so continue after it */
 159                 if (block->start == cur_start) {
 160                         cur_start = block->start + block->size;
 161                         continue;
 162                 }
 163
 164                 /*
 165                  * allocate the space between the current starting
 166                  * address and the following reserved block, or the
 167                  * end of the region.
 168                  */
 169                 cur_size = block->start - cur_start;
 170
 171                 dev_dbg(&pdev->dev, "adding chunk 0x%lx-0x%lx\n",
 172                         cur_start, cur_start + cur_size);
 173                 ret = gen_pool_add_virt(sram->pool,
 174                                 (unsigned long)virt_base + cur_start,
 175                                 res->start + cur_start, cur_size, -1);
 176                 if (ret < 0)
 177                         goto err_chunks;
 178
 179                 /* next allocation after this reserved block */
 180                 cur_start = block->start + block->size;
 181         }
 182
 183         kfree(rblocks);
 184
 185         sram->clk = devm_clk_get(&pdev->dev, NULL);
 186         if (IS_ERR(sram->clk))
 187                 sram->clk = NULL;
 188         else
 189                 clk_prepare_enable(sram->clk);
 190
 191         platform_set_drvdata(pdev, sram);
 192
 193         dev_dbg(&pdev->dev, "SRAM pool: %zu KiB @ 0x%p\n",
 194                 gen_pool_size(sram->pool) / 1024, virt_base);
 195
 196         return 0;
 197
 198 err_chunks:
 199         kfree(rblocks);
 200
 201         return ret;
 202 }
 203
 204 static int sram_remove(struct platform_device *pdev)
 205 {
 206         struct sram_dev *sram = platform_get_drvdata(pdev);
 207
 208         if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
 209                 dev_err(&pdev->dev, "removed while SRAM allocated\n");
 210
 211         if (sram->clk)
 212                 clk_disable_unprepare(sram->clk);
 213
 214         return 0;
 215 }
 216
 217 #ifdef CONFIG_OF
 218 static const struct of_device_id sram_dt_ids[] = {
 219         { .compatible = "mmio-sram" },
 220         {}
 221 };
 222 #endif
 223
 224 static struct platform_driver sram_driver = {
 225         .driver = {
 226                 .name = "sram",
 227                 .of_match_table = of_match_ptr(sram_dt_ids),
 228         },
 229         .probe = sram_probe,
 230         .remove = sram_remove,
 231 };
 232
 233 static int __init sram_init(void)
 234 {
 235         return platform_driver_register(&sram_driver);
 236 }
 237
 238 postcore_initcall(sram_init);