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 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 65 static int kirkwood_cpuidle_remove(struct platform_device *pdev) 66 { 67 cpuidle_unregister(&kirkwood_idle_driver); 68 return 0; 69 } 70 71 static 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 79 module_platform_driver(kirkwood_cpuidle_driver); 80 81 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>"); 82 MODULE_DESCRIPTION("Kirkwood cpu idle driver"); 83 MODULE_LICENSE("GPL v2"); 84 MODULE_ALIAS("platform:kirkwood-cpuidle"); 85