1 /* 2 * linux/arch/arm/kernel/smp_scu.c 3 * 4 * Copyright (C) 2002 ARM Ltd. 5 * All Rights Reserved 6 * 7 * This program is free software; you can redistribute it and/or modify 8 * it under the terms of the GNU General Public License version 2 as 9 * published by the Free Software Foundation. 10 */ 11 #include <linux/init.h> 12 #include <linux/io.h> 13 14 #include <asm/smp_scu.h> 15 #include <asm/cacheflush.h> 16 17 #define SCU_CTRL 0x00 18 #define SCU_CONFIG 0x04 19 #define SCU_CPU_STATUS 0x08 20 #define SCU_INVALIDATE 0x0c 21 #define SCU_FPGA_REVISION 0x10 22 23 /* 24 * Get the number of CPU cores from the SCU configuration 25 */ 26 unsigned int __init scu_get_core_count(void __iomem *scu_base) 27 { 28 unsigned int ncores = __raw_readl(scu_base + SCU_CONFIG); 29 return (ncores & 0x03) + 1; 30 } 31 32 /* 33 * Enable the SCU 34 */ 35 void __init scu_enable(void __iomem *scu_base) 36 { 37 u32 scu_ctrl; 38 39 scu_ctrl = __raw_readl(scu_base + SCU_CTRL); 40 /* already enabled? */ 41 if (scu_ctrl & 1) 42 return; 43 44 scu_ctrl |= 1; 45 __raw_writel(scu_ctrl, scu_base + SCU_CTRL); 46 47 /* 48 * Ensure that the data accessed by CPU0 before the SCU was 49 * initialised is visible to the other CPUs. 50 */ 51 flush_cache_all(); 52 } 53 54 /* 55 * Set the executing CPUs power mode as defined. This will be in 56 * preparation for it executing a WFI instruction. 57 * 58 * This function must be called with preemption disabled, and as it 59 * has the side effect of disabling coherency, caches must have been 60 * flushed. Interrupts must also have been disabled. 61 */ 62 int scu_power_mode(void __iomem *scu_base, unsigned int mode) 63 { 64 unsigned int val; 65 int cpu = smp_processor_id(); 66 67 if (mode > 3 || mode == 1 || cpu > 3) 68 return -EINVAL; 69 70 val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03; 71 val |= mode; 72 __raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu); 73 74 return 0; 75 } 76