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/platform_device.h>
  28 #include <linux/slab.h>
  29 #include <linux/spinlock.h>
  30 #include <linux/genalloc.h>
  31
  32 #define SRAM_GRANULARITY        32
  33
  34 struct sram_dev {
  35         struct gen_pool *pool;
  36         struct clk *clk;
  37 };
  38
  39 static int sram_probe(struct platform_device *pdev)
  40 {
  41         void __iomem *virt_base;
  42         struct sram_dev *sram;
  43         struct resource *res;
  44         unsigned long size;
  45         int ret;
  46
  47         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  48         virt_base = devm_ioremap_resource(&pdev->dev, res);
  49         if (IS_ERR(virt_base))
  50                 return PTR_ERR(virt_base);
  51
  52         size = resource_size(res);
  53
  54         sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
  55         if (!sram)
  56                 return -ENOMEM;
  57
  58         sram->clk = devm_clk_get(&pdev->dev, NULL);
  59         if (IS_ERR(sram->clk))
  60                 sram->clk = NULL;
  61         else
  62                 clk_prepare_enable(sram->clk);
  63
  64         sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -1);
  65         if (!sram->pool)
  66                 return -ENOMEM;
  67
  68         ret = gen_pool_add_virt(sram->pool, (unsigned long)virt_base,
  69                                 res->start, size, -1);
  70         if (ret < 0) {
  71                 gen_pool_destroy(sram->pool);
  72                 return ret;
  73         }
  74
  75         platform_set_drvdata(pdev, sram);
  76
  77         dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p\n", size / 1024, virt_base);
  78
  79         return 0;
  80 }
  81
  82 static int sram_remove(struct platform_device *pdev)
  83 {
  84         struct sram_dev *sram = platform_get_drvdata(pdev);
  85
  86         if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
  87                 dev_dbg(&pdev->dev, "removed while SRAM allocated\n");
  88
  89         gen_pool_destroy(sram->pool);
  90
  91         if (sram->clk)
  92                 clk_disable_unprepare(sram->clk);
  93
  94         return 0;
  95 }
  96
  97 #ifdef CONFIG_OF
  98 static struct of_device_id sram_dt_ids[] = {
  99         { .compatible = "mmio-sram" },
 100         {}
 101 };
 102 #endif
 103
 104 static struct platform_driver sram_driver = {
 105         .driver = {
 106                 .name = "sram",
 107                 .of_match_table = of_match_ptr(sram_dt_ids),
 108         },
 109         .probe = sram_probe,
 110         .remove = sram_remove,
 111 };
 112
 113 static int __init sram_init(void)
 114 {
 115         return platform_driver_register(&sram_driver);
 116 }
 117
 118 postcore_initcall(sram_init);