diff options
Diffstat (limited to '')
-rw-r--r-- | drivers/clocksource/clksrc-dbx500-prcmu.c | 72 |
1 files changed, 72 insertions, 0 deletions
diff --git a/drivers/clocksource/clksrc-dbx500-prcmu.c b/drivers/clocksource/clksrc-dbx500-prcmu.c new file mode 100644 index 000000000..2fc93e46c --- /dev/null +++ b/drivers/clocksource/clksrc-dbx500-prcmu.c @@ -0,0 +1,72 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Copyright (C) ST-Ericsson SA 2011 + * + * 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. + */ +#include <linux/of.h> +#include <linux/of_address.h> +#include <linux/clockchips.h> + +#define RATE_32K 32768 + +#define TIMER_MODE_CONTINUOUS 0x1 +#define TIMER_DOWNCOUNT_VAL 0xffffffff + +#define PRCMU_TIMER_REF 0 +#define PRCMU_TIMER_DOWNCOUNT 0x4 +#define PRCMU_TIMER_MODE 0x8 + +static void __iomem *clksrc_dbx500_timer_base; + +static u64 notrace clksrc_dbx500_prcmu_read(struct clocksource *cs) +{ + void __iomem *base = clksrc_dbx500_timer_base; + u32 count, count2; + + do { + count = readl_relaxed(base + PRCMU_TIMER_DOWNCOUNT); + count2 = readl_relaxed(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 = 100, + .read = clksrc_dbx500_prcmu_read, + .mask = CLOCKSOURCE_MASK(32), + .flags = CLOCK_SOURCE_IS_CONTINUOUS | CLOCK_SOURCE_SUSPEND_NONSTOP, +}; + +static int __init clksrc_dbx500_prcmu_init(struct device_node *node) +{ + clksrc_dbx500_timer_base = of_iomap(node, 0); + + /* + * The A9 sub system expects the timer to be configured as + * a continuous 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_CONTINUOUS) { + writel(TIMER_MODE_CONTINUOUS, + clksrc_dbx500_timer_base + PRCMU_TIMER_MODE); + writel(TIMER_DOWNCOUNT_VAL, + clksrc_dbx500_timer_base + PRCMU_TIMER_REF); + } + return clocksource_register_hz(&clocksource_dbx500_prcmu, RATE_32K); +} +TIMER_OF_DECLARE(dbx500_prcmu, "stericsson,db8500-prcmu-timer-4", + clksrc_dbx500_prcmu_init); |