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 #ifdef CONFIG_SMP 24 /* 25 * Get the number of CPU cores from the SCU configuration 26 */ 27 unsigned int __init scu_get_core_count(void __iomem *scu_base) 28 { 29 unsigned int ncores = __raw_readl(scu_base + SCU_CONFIG); 30 return (ncores & 0x03) + 1; 31 } 32 33 /* 34 * Enable the SCU 35 */ 36 void __init scu_enable(void __iomem *scu_base) 37 { 38 u32 scu_ctrl; 39 40 scu_ctrl = __raw_readl(scu_base + SCU_CTRL); 41 /* already enabled? */ 42 if (scu_ctrl & 1) 43 return; 44 45 scu_ctrl |= 1; 46 __raw_writel(scu_ctrl, scu_base + SCU_CTRL); 47 48 /* 49 * Ensure that the data accessed by CPU0 before the SCU was 50 * initialised is visible to the other CPUs. 51 */ 52 flush_cache_all(); 53 } 54 #endif 55 56 /* 57 * Set the executing CPUs power mode as defined. This will be in 58 * preparation for it executing a WFI instruction. 59 * 60 * This function must be called with preemption disabled, and as it 61 * has the side effect of disabling coherency, caches must have been 62 * flushed. Interrupts must also have been disabled. 63 */ 64 int scu_power_mode(void __iomem *scu_base, unsigned int mode) 65 { 66 unsigned int val; 67 int cpu = smp_processor_id(); 68 69 if (mode > 3 || mode == 1 || cpu > 3) 70 return -EINVAL; 71 72 val = __raw_readb(scu_base + SCU_CPU_STATUS + cpu) & ~0x03; 73 val |= mode; 74 __raw_writeb(val, scu_base + SCU_CPU_STATUS + cpu); 75 76 return 0; 77 } 78