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/proc-fns.h>
  25#include <asm/cpuidle.h>
  26
  27#define KIRKWOOD_MAX_STATES     2
  28
  29static void __iomem *ddr_operation_base;
  30
  31/* Actual code that puts the SoC in different idle states */
  32static int kirkwood_enter_idle(struct cpuidle_device *dev,
  33                               struct cpuidle_driver *drv,
  34                               int index)
  35{
  36        writel(0x7, ddr_operation_base);
  37        cpu_do_idle();
  38
  39        return index;
  40}
  41
  42static struct cpuidle_driver kirkwood_idle_driver = {
  43        .name                   = "kirkwood_idle",
  44        .owner                  = THIS_MODULE,
  45        .states[0]              = ARM_CPUIDLE_WFI_STATE,
  46        .states[1]              = {
  47                .enter                  = kirkwood_enter_idle,
  48                .exit_latency           = 10,
  49                .target_residency       = 100000,
  50                .flags                  = CPUIDLE_FLAG_TIME_VALID,
  51                .name                   = "DDR SR",
  52                .desc                   = "WFI and DDR Self Refresh",
  53        },
  54        .state_count = KIRKWOOD_MAX_STATES,
  55};
  56
  57/* Initialize CPU idle by registering the idle states */
  58static int kirkwood_cpuidle_probe(struct platform_device *pdev)
  59{
  60        struct resource *res;
  61
  62        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  63        ddr_operation_base = devm_ioremap_resource(&pdev->dev, res);
  64        if (IS_ERR(ddr_operation_base))
  65                return PTR_ERR(ddr_operation_base);
  66
  67        return cpuidle_register(&kirkwood_idle_driver, NULL);
  68}
  69
  70static int kirkwood_cpuidle_remove(struct platform_device *pdev)
  71{
  72        cpuidle_unregister(&kirkwood_idle_driver);
  73        return 0;
  74}
  75
  76static struct platform_driver kirkwood_cpuidle_driver = {
  77        .probe = kirkwood_cpuidle_probe,
  78        .remove = kirkwood_cpuidle_remove,
  79        .driver = {
  80                   .name = "kirkwood_cpuidle",
  81                   .owner = THIS_MODULE,
  82                   },
  83};
  84
  85module_platform_driver(kirkwood_cpuidle_driver);
  86
  87MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
  88MODULE_DESCRIPTION("Kirkwood cpu idle driver");
  89MODULE_LICENSE("GPL v2");
  90MODULE_ALIAS("platform:kirkwood-cpuidle");
  91
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