/* * Copyright (C) ST-Ericsson SA 2011 * * License Terms: GNU General Public License v2 * Author: Mattias Wallin <mattias.wallin@stericsson.com> for ST-Ericsson * Author: Sundar Iyer for ST-Ericsson * sched_clock implementation is based on: * plat-nomadik/timer.c Linus Walleij <linus.walleij@stericsson.com> * * DBx500-PRCMU Timer * The PRCMU has 5 timers which are available in a always-on * power domain. We use the Timer 4 for our always-on clock * source on DB8500 and Timer 3 on DB5500. */ #include <linux/clockchips.h> #include <linux/clksrc-dbx500-prcmu.h> #include <asm/sched_clock.h> #include <mach/setup.h> #include <mach/hardware.h> #define RATE_32K 32768 #define TIMER_MODE_CONTINOUS 0x1 #define TIMER_DOWNCOUNT_VAL 0xffffffff #define PRCMU_TIMER_REF 0 #define PRCMU_TIMER_DOWNCOUNT 0x4 #define PRCMU_TIMER_MODE 0x8 #define SCHED_CLOCK_MIN_WRAP 131072 /* 2^32 / 32768 */ static void __iomem *clksrc_dbx500_timer_base; static cycle_t clksrc_dbx500_prcmu_read(struct clocksource *cs) { u32 count, count2; do { count = readl(clksrc_dbx500_timer_base + PRCMU_TIMER_DOWNCOUNT); count2 = readl(clksrc_dbx500_timer_base + PRCMU_TIMER_DOWNCOUNT); } while (count2 != count); /* Negate because the timer is a decrementing counter */ return ~count; } static struct clocksource clocksource_dbx500_prcmu = { .name = "dbx500-prcmu-timer", .rating = 300, .read = clksrc_dbx500_prcmu_read, .shift = 10, .mask = CLOCKSOURCE_MASK(32), .flags = CLOCK_SOURCE_IS_CONTINUOUS, }; #ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK static u32 notrace dbx500_prcmu_sched_clock_read(void) { if (unlikely(!clksrc_dbx500_timer_base)) return 0; return clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu); } #endif void __init clksrc_dbx500_prcmu_init(void __iomem *base) { clksrc_dbx500_timer_base = base; /* * The A9 sub system expects the timer to be configured as * a continous looping timer. * The PRCMU should configure it but if it for some reason * don't we do it here. */ if (readl(clksrc_dbx500_timer_base + PRCMU_TIMER_MODE) != TIMER_MODE_CONTINOUS) { writel(TIMER_MODE_CONTINOUS, clksrc_dbx500_timer_base + PRCMU_TIMER_MODE); writel(TIMER_DOWNCOUNT_VAL, clksrc_dbx500_timer_base + PRCMU_TIMER_REF); } #ifdef CONFIG_CLKSRC_DBX500_PRCMU_SCHED_CLOCK setup_sched_clock(dbx500_prcmu_sched_clock_read, 32, RATE_32K); #endif clocksource_calc_mult_shift(&clocksource_dbx500_prcmu, RATE_32K, SCHED_CLOCK_MIN_WRAP); clocksource_register(&clocksource_dbx500_prcmu); }