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 #define MMDC_MDMISC             0x18
  25 #define BM_MMDC_MDMISC_DDR_TYPE 0x18
  26 #define BP_MMDC_MDMISC_DDR_TYPE 0x3
  27
  28 static int ddr_type;
  29
  30 static int imx_mmdc_probe(struct platform_device *pdev)
  31 {
  32         struct device_node *np = pdev->dev.of_node;
  33         void __iomem *mmdc_base, *reg;
  34         u32 val;
  35         int timeout = 0x400;
  36
  37         mmdc_base = of_iomap(np, 0);
  38         WARN_ON(!mmdc_base);
  39
  40         reg = mmdc_base + MMDC_MDMISC;
  41         /* Get ddr type */
  42         val = readl_relaxed(reg);
  43         ddr_type = (val & BM_MMDC_MDMISC_DDR_TYPE) >>
  44                  BP_MMDC_MDMISC_DDR_TYPE;
  45
  46         reg = mmdc_base + MMDC_MAPSR;
  47
  48         /* Enable automatic power saving */
  49         val = readl_relaxed(reg);
  50         val &= ~(1 << BP_MMDC_MAPSR_PSD);
  51         writel_relaxed(val, reg);
  52
  53         /* Ensure it's successfully enabled */
  54         while (!(readl_relaxed(reg) & 1 << BP_MMDC_MAPSR_PSS) && --timeout)
  55                 cpu_relax();
  56
  57         if (unlikely(!timeout)) {
  58                 pr_warn("%s: failed to enable automatic power saving\n",
  59                         __func__);
  60                 return -EBUSY;
  61         }
  62
  63         return 0;
  64 }
  65
  66 int imx_mmdc_get_ddr_type(void)
  67 {
  68         return ddr_type;
  69 }
  70
  71 static const struct of_device_id imx_mmdc_dt_ids[] = {
  72         { .compatible = "fsl,imx6q-mmdc", },
  73         { /* sentinel */ }
  74 };
  75
  76 static struct platform_driver imx_mmdc_driver = {
  77         .driver         = {
  78                 .name   = "imx-mmdc",
  79                 .of_match_table = imx_mmdc_dt_ids,
  80         },
  81         .probe          = imx_mmdc_probe,
  82 };
  83
  84 static int __init imx_mmdc_init(void)
  85 {
  86         return platform_driver_register(&imx_mmdc_driver);
  87 }
  88 postcore_initcall(imx_mmdc_init);