1 /* 2 * Copyright (C) 2012-2013 Xilinx 3 * 4 * CPU idle support for Xilinx Zynq 5 * 6 * based on arch/arm/mach-at91/cpuidle.c 7 * 8 * This program is free software; you can redistribute it and/or modify it 9 * under the terms and conditions of the GNU General Public License, 10 * version 2, as published by the Free Software Foundation. 11 * 12 * This program is distributed in the hope it will be useful, but WITHOUT 13 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 14 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for 15 * more details. 16 * 17 * You should have received a copy of the GNU General Public License along with 18 * this program. If not, see <http://www.gnu.org/licenses/>. 19 * 20 * The cpu idle uses wait-for-interrupt and RAM self refresh in order 21 * to implement two idle states - 22 * #1 wait-for-interrupt 23 * #2 wait-for-interrupt and RAM self refresh 24 * 25 * Maintainer: Michal Simek <michal.simek@xilinx.com> 26 */ 27 28 #include <linux/init.h> 29 #include <linux/cpuidle.h> 30 #include <linux/platform_device.h> 31 #include <asm/proc-fns.h> 32 #include <asm/cpuidle.h> 33 34 #define ZYNQ_MAX_STATES 2 35 36 /* Actual code that puts the SoC in different idle states */ 37 static int zynq_enter_idle(struct cpuidle_device *dev, 38 struct cpuidle_driver *drv, int index) 39 { 40 /* Add code for DDR self refresh start */ 41 cpu_do_idle(); 42 43 return index; 44 } 45 46 static struct cpuidle_driver zynq_idle_driver = { 47 .name = "zynq_idle", 48 .owner = THIS_MODULE, 49 .states = { 50 ARM_CPUIDLE_WFI_STATE, 51 { 52 .enter = zynq_enter_idle, 53 .exit_latency = 10, 54 .target_residency = 10000, 55 .name = "RAM_SR", 56 .desc = "WFI and RAM Self Refresh", 57 }, 58 }, 59 .safe_state_index = 0, 60 .state_count = ZYNQ_MAX_STATES, 61 }; 62 63 /* Initialize CPU idle by registering the idle states */ 64 static int zynq_cpuidle_probe(struct platform_device *pdev) 65 { 66 pr_info("Xilinx Zynq CpuIdle Driver started\n"); 67 68 return cpuidle_register(&zynq_idle_driver, NULL); 69 } 70 71 static struct platform_driver zynq_cpuidle_driver = { 72 .driver = { 73 .name = "cpuidle-zynq", 74 }, 75 .probe = zynq_cpuidle_probe, 76 }; 77 78 module_platform_driver(zynq_cpuidle_driver); 79