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kernel/linux-imx6_3.14.28/drivers/misc/sram.c 2.83 KB
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  /*
   * Generic on-chip SRAM allocation driver
   *
   * Copyright (C) 2012 Philipp Zabel, Pengutronix
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License
   * as published by the Free Software Foundation; either version 2
   * of the License, or (at your option) any later version.
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   * MA 02110-1301, USA.
   */
  
  #include <linux/kernel.h>
  #include <linux/init.h>
  #include <linux/clk.h>
  #include <linux/err.h>
  #include <linux/io.h>
  #include <linux/of.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>
  #include <linux/genalloc.h>
  
  #define SRAM_GRANULARITY	4096
  
  struct sram_dev {
  	struct gen_pool *pool;
  	struct clk *clk;
  };
  
  static int sram_probe(struct platform_device *pdev)
  {
  	void __iomem *virt_base;
  	struct sram_dev *sram;
  	struct resource *res;
  	unsigned long size;
  	int ret;
  
  	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	virt_base = devm_ioremap_resource(&pdev->dev, res);
  	if (IS_ERR(virt_base))
  		return PTR_ERR(virt_base);
  
  	size = resource_size(res);
  
  	sram = devm_kzalloc(&pdev->dev, sizeof(*sram), GFP_KERNEL);
  	if (!sram)
  		return -ENOMEM;
  
  	sram->clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(sram->clk))
  		sram->clk = NULL;
  	else
  		clk_prepare_enable(sram->clk);
  
  	sram->pool = devm_gen_pool_create(&pdev->dev, ilog2(SRAM_GRANULARITY), -1);
  	if (!sram->pool)
  		return -ENOMEM;
  
  	ret = gen_pool_add_virt(sram->pool, (unsigned long)virt_base,
  				res->start, size, -1);
  	if (ret < 0) {
  		if (sram->clk)
  			clk_disable_unprepare(sram->clk);
  		return ret;
  	}
  
  	platform_set_drvdata(pdev, sram);
  
  	dev_dbg(&pdev->dev, "SRAM pool: %ld KiB @ 0x%p
  ", size / 1024, virt_base);
  
  	return 0;
  }
  
  static int sram_remove(struct platform_device *pdev)
  {
  	struct sram_dev *sram = platform_get_drvdata(pdev);
  
  	if (gen_pool_avail(sram->pool) < gen_pool_size(sram->pool))
  		dev_dbg(&pdev->dev, "removed while SRAM allocated
  ");
  
  	gen_pool_destroy(sram->pool);
  
  	if (sram->clk)
  		clk_disable_unprepare(sram->clk);
  
  	return 0;
  }
  
  #ifdef CONFIG_OF
  static struct of_device_id sram_dt_ids[] = {
  	{ .compatible = "mmio-sram" },
  	{}
  };
  #endif
  
  static struct platform_driver sram_driver = {
  	.driver = {
  		.name = "sram",
  		.of_match_table = of_match_ptr(sram_dt_ids),
  	},
  	.probe = sram_probe,
  	.remove = sram_remove,
  };
  
  static int __init sram_init(void)
  {
  	return platform_driver_register(&sram_driver);
  }
  
  postcore_initcall(sram_init);