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); 73