linux/drivers/cpuidle/cpuidle-kirkwood.c
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   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
  28static void __iomem *ddr_operation_base;
  29
  30/* Actual code that puts the SoC in different idle states */
  31static 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
  41static 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 */
  56static int kirkwood_cpuidle_probe(struct platform_device *pdev)
  57{
  58        ddr_operation_base = devm_platform_ioremap_resource(pdev, 0);
  59        if (IS_ERR(ddr_operation_base))
  60                return PTR_ERR(ddr_operation_base);
  61
  62        return cpuidle_register(&kirkwood_idle_driver, NULL);
  63}
  64
  65static int kirkwood_cpuidle_remove(struct platform_device *pdev)
  66{
  67        cpuidle_unregister(&kirkwood_idle_driver);
  68        return 0;
  69}
  70
  71static struct platform_driver kirkwood_cpuidle_driver = {
  72        .probe = kirkwood_cpuidle_probe,
  73        .remove = kirkwood_cpuidle_remove,
  74        .driver = {
  75                   .name = "kirkwood_cpuidle",
  76                   },
  77};
  78
  79module_platform_driver(kirkwood_cpuidle_driver);
  80
  81MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
  82MODULE_DESCRIPTION("Kirkwood cpu idle driver");
  83MODULE_LICENSE("GPL v2");
  84MODULE_ALIAS("platform:kirkwood-cpuidle");
  85