kernel/drivers/cpuidle/cpuidle-kirkwood.c

   1 /*
   2  * CPU idle Marvell Kirkwood SoCs
   3  *
   4  * This file is licensed under the terms of the GNU General Public
   5  * License version 2.  This program is licensed "as is" without any
   6  * warranty of any kind, whether express or implied.
   7  *
   8  * The cpu idle uses wait-for-interrupt and DDR self refresh in order
   9  * to implement two idle states -
  10  * #1 wait-for-interrupt
  11  * #2 wait-for-interrupt and DDR self refresh
  12  *
  13  * Maintainer: Jason Cooper <jason@lakedaemon.net>
  14  * Maintainer: Andrew Lunn <andrew@lunn.ch>
  15  */
  16
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/init.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/cpuidle.h>
  22 #include <linux/io.h>
  23 #include <linux/export.h>
  24 #include <asm/cpuidle.h>
  25
  26 #define KIRKWOOD_MAX_STATES     2
  27
  28 static void __iomem *ddr_operation_base;
  29
  30 /* Actual code that puts the SoC in different idle states */
  31 static int kirkwood_enter_idle(struct cpuidle_device *dev,
  32                                struct cpuidle_driver *drv,
  33                                int index)
  34 {
  35         writel(0x7, ddr_operation_base);
  36         cpu_do_idle();
  37
  38         return index;
  39 }
  40
  41 static struct cpuidle_driver kirkwood_idle_driver = {
  42         .name                   = "kirkwood_idle",
  43         .owner                  = THIS_MODULE,
  44         .states[0]              = ARM_CPUIDLE_WFI_STATE,
  45         .states[1]              = {
  46                 .enter                  = kirkwood_enter_idle,
  47                 .exit_latency           = 10,
  48                 .target_residency       = 100000,
  49                 .name                   = "DDR SR",
  50                 .desc                   = "WFI and DDR Self Refresh",
  51         },
  52         .state_count = KIRKWOOD_MAX_STATES,
  53 };
  54
  55 /* Initialize CPU idle by registering the idle states */
  56 static int kirkwood_cpuidle_probe(struct platform_device *pdev)
  57 {
  58         struct resource *res;
  59
  60         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  61         ddr_operation_base = devm_ioremap_resource(&pdev->dev, res);
  62         if (IS_ERR(ddr_operation_base))
  63                 return PTR_ERR(ddr_operation_base);
  64
  65         return cpuidle_register(&kirkwood_idle_driver, NULL);
  66 }
  67
  68 static int kirkwood_cpuidle_remove(struct platform_device *pdev)
  69 {
  70         cpuidle_unregister(&kirkwood_idle_driver);
  71         return 0;
  72 }
  73
  74 static struct platform_driver kirkwood_cpuidle_driver = {
  75         .probe = kirkwood_cpuidle_probe,
  76         .remove = kirkwood_cpuidle_remove,
  77         .driver = {
  78                    .name = "kirkwood_cpuidle",
  79                    },
  80 };
  81
  82 module_platform_driver(kirkwood_cpuidle_driver);
  83
  84 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
  85 MODULE_DESCRIPTION("Kirkwood cpu idle driver");
  86 MODULE_LICENSE("GPL v2");
  87 MODULE_ALIAS("platform:kirkwood-cpuidle");