From 489bccea6334514a8e13436f10d0a274777bf17a Mon Sep 17 00:00:00 2001 From: Mattias Wallin Date: Fri, 27 May 2011 10:30:12 +0200 Subject: clocksource: add DBX500 PRCMU Timer support This patch adds the DBX500 PRCMU Timer driver as a clocksource and as sched_clock. Cc: Thomas Gleixner Signed-off-by: Mattias Wallin Signed-off-by: Jonas Aaberg Signed-off-by: Linus Walleij --- drivers/clocksource/clksrc-dbx500-prcmu.c | 104 ++++++++++++++++++++++++++++++ 1 file changed, 104 insertions(+) create mode 100644 drivers/clocksource/clksrc-dbx500-prcmu.c (limited to 'drivers/clocksource/clksrc-dbx500-prcmu.c') diff --git a/drivers/clocksource/clksrc-dbx500-prcmu.c b/drivers/clocksource/clksrc-dbx500-prcmu.c new file mode 100644 index 000000000000..0ac5093a053a --- /dev/null +++ b/drivers/clocksource/clksrc-dbx500-prcmu.c @@ -0,0 +1,104 @@ +/* + * Copyright (C) ST-Ericsson SA 2011 + * + * License Terms: GNU General Public License v2 + * Author: Mattias Wallin for ST-Ericsson + * Author: Sundar Iyer for ST-Ericsson + * sched_clock implementation is based on: + * plat-nomadik/timer.c Linus Walleij + * + * 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 +#include + +#include + +#include +#include + +#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 */ + +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 DEFINE_CLOCK_DATA(cd); + +unsigned long long notrace sched_clock(void) +{ + u32 cyc; + + if (unlikely(!clksrc_dbx500_timer_base)) + return 0; + + cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu); + + return cyc_to_sched_clock(&cd, cyc, (u32)~0); +} + +static void notrace clksrc_dbx500_prcmu_update_sched_clock(void) +{ + u32 cyc = clksrc_dbx500_prcmu_read(&clocksource_dbx500_prcmu); + update_sched_clock(&cd, cyc, (u32)~0); +} +#endif + +void __init clksrc_dbx500_prcmu_init(void) +{ + /* + * 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 + init_sched_clock(&cd, clksrc_dbx500_prcmu_update_sched_clock, + 32, RATE_32K); +#endif + clocksource_calc_mult_shift(&clocksource_dbx500_prcmu, + RATE_32K, SCHED_CLOCK_MIN_WRAP); + clocksource_register(&clocksource_dbx500_prcmu); +} -- cgit v1.2.3