arch/arm/mach-imx/mmdc.c

   1 /*
   2  * Copyright 2011 Freescale Semiconductor, Inc.
   3  * Copyright 2011 Linaro Ltd.
   4  *
   5  * The code contained herein is licensed under the GNU General Public
   6  * License. You may obtain a copy of the GNU General Public License
   7  * Version 2 or later at the following locations:
   8  *
   9  * http://www.opensource.org/licenses/gpl-license.html
  10  * http://www.gnu.org/copyleft/gpl.html
  11  */
  12
  13 #include <linux/init.h>
  14 #include <linux/io.h>
  15 #include <linux/module.h>
  16 #include <linux/of.h>
  17 #include <linux/of_address.h>
  18 #include <linux/of_device.h>
  19
  20 #define MMDC_MAPSR              0x404
  21 #define BP_MMDC_MAPSR_PSD       0
  22 #define BP_MMDC_MAPSR_PSS       4
  23
  24 static int imx_mmdc_probe(struct platform_device *pdev)
  25 {
  26         struct device_node *np = pdev->dev.of_node;
  27         void __iomem *mmdc_base, *reg;
  28         u32 val;
  29         int timeout = 0x400;
  30
  31         mmdc_base = of_iomap(np, 0);
  32         WARN_ON(!mmdc_base);
  33
  34         reg = mmdc_base + MMDC_MAPSR;
  35
  36         /* Enable automatic power saving */
  37         val = readl_relaxed(reg);
  38         val &= ~(1 << BP_MMDC_MAPSR_PSD);
  39         writel_relaxed(val, reg);
  40
  41         /* Ensure it's successfully enabled */
  42         while (!(readl_relaxed(reg) & 1 << BP_MMDC_MAPSR_PSS) && --timeout)
  43                 cpu_relax();
  44
  45         if (unlikely(!timeout)) {
  46                 pr_warn("%s: failed to enable automatic power saving\n",
  47                         __func__);
  48                 return -EBUSY;
  49         }
  50
  51         return 0;
  52 }
  53
  54 static struct of_device_id imx_mmdc_dt_ids[] = {
  55         { .compatible = "fsl,imx6q-mmdc", },
  56         { /* sentinel */ }
  57 };
  58
  59 static struct platform_driver imx_mmdc_driver = {
  60         .driver         = {
  61                 .name   = "imx-mmdc",
  62                 .owner  = THIS_MODULE,
  63                 .of_match_table = imx_mmdc_dt_ids,
  64         },
  65         .probe          = imx_mmdc_probe,
  66 };
  67
  68 static int __init imx_mmdc_init(void)
  69 {
  70         return platform_driver_register(&imx_mmdc_driver);
  71 }
  72 postcore_initcall(imx_mmdc_init);