1 /* 2 * Copyright 2011 Freescale Semiconductor, Inc. 3 * Copyright 2011 Linaro Ltd. 4 * 5 * The code contained herein is licensed under the GNU General Public 6 * License. You may obtain a copy of the GNU General Public License 7 * Version 2 or later at the following locations: 8 * 9 * http://www.opensource.org/licenses/gpl-license.html 10 * http://www.gnu.org/copyleft/gpl.html 11 */ 12 13 #include <linux/errno.h> 14 #include <linux/jiffies.h> 15 #include <asm/cp15.h> 16 #include <asm/proc-fns.h> 17 18 #include "common.h" 19 20 static inline void cpu_enter_lowpower(void) 21 { 22 unsigned int v; 23 24 asm volatile( 25 "mcr p15, 0, %1, c7, c5, 0\n" 26 " mcr p15, 0, %1, c7, c10, 4\n" 27 /* 28 * Turn off coherency 29 */ 30 " mrc p15, 0, %0, c1, c0, 1\n" 31 " bic %0, %0, %3\n" 32 " mcr p15, 0, %0, c1, c0, 1\n" 33 " mrc p15, 0, %0, c1, c0, 0\n" 34 " bic %0, %0, %2\n" 35 " mcr p15, 0, %0, c1, c0, 0\n" 36 : "=&r" (v) 37 : "r" (0), "Ir" (CR_C), "Ir" (0x40) 38 : "cc"); 39 } 40 41 /* 42 * platform-specific code to shutdown a CPU 43 * 44 * Called with IRQs disabled 45 */ 46 void imx_cpu_die(unsigned int cpu) 47 { 48 cpu_enter_lowpower(); 49 /* 50 * We use the cpu jumping argument register to sync with 51 * imx_cpu_kill() which is running on cpu0 and waiting for 52 * the register being cleared to kill the cpu. 53 */ 54 imx_set_cpu_arg(cpu, ~0); 55 56 while (1) 57 cpu_do_idle(); 58 } 59 60 int imx_cpu_kill(unsigned int cpu) 61 { 62 unsigned long timeout = jiffies + msecs_to_jiffies(50); 63 64 while (imx_get_cpu_arg(cpu) == 0) 65 if (time_after(jiffies, timeout)) 66 return 0; 67 imx_enable_cpu(cpu, false); 68 imx_set_cpu_arg(cpu, 0); 69 return 1; 70 } 71