diff options
Diffstat (limited to 'arch/arm/mach-prima2/timer.c')
| -rw-r--r-- | arch/arm/mach-prima2/timer.c | 218 |
1 files changed, 218 insertions, 0 deletions
diff --git a/arch/arm/mach-prima2/timer.c b/arch/arm/mach-prima2/timer.c new file mode 100644 index 00000000000..ed7ec48d11d --- /dev/null +++ b/arch/arm/mach-prima2/timer.c @@ -0,0 +1,218 @@ +/* + * System timer for CSR SiRFprimaII + * + * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company. + * + * Licensed under GPLv2 or later. + */ + +#include <linux/kernel.h> +#include <linux/interrupt.h> +#include <linux/clockchips.h> +#include <linux/clocksource.h> +#include <linux/bitops.h> +#include <linux/irq.h> +#include <linux/clk.h> +#include <linux/err.h> +#include <linux/slab.h> +#include <linux/of.h> +#include <linux/of_address.h> +#include <mach/map.h> +#include <asm/mach/time.h> + +#define SIRFSOC_TIMER_COUNTER_LO 0x0000 +#define SIRFSOC_TIMER_COUNTER_HI 0x0004 +#define SIRFSOC_TIMER_MATCH_0 0x0008 +#define SIRFSOC_TIMER_MATCH_1 0x000C +#define SIRFSOC_TIMER_MATCH_2 0x0010 +#define SIRFSOC_TIMER_MATCH_3 0x0014 +#define SIRFSOC_TIMER_MATCH_4 0x0018 +#define SIRFSOC_TIMER_MATCH_5 0x001C +#define SIRFSOC_TIMER_STATUS 0x0020 +#define SIRFSOC_TIMER_INT_EN 0x0024 +#define SIRFSOC_TIMER_WATCHDOG_EN 0x0028 +#define SIRFSOC_TIMER_DIV 0x002C +#define SIRFSOC_TIMER_LATCH 0x0030 +#define SIRFSOC_TIMER_LATCHED_LO 0x0034 +#define SIRFSOC_TIMER_LATCHED_HI 0x0038 + +#define SIRFSOC_TIMER_WDT_INDEX 5 + +#define SIRFSOC_TIMER_LATCH_BIT BIT(0) + +static void __iomem *sirfsoc_timer_base; +static void __init sirfsoc_of_timer_map(void); + +/* timer0 interrupt handler */ +static irqreturn_t sirfsoc_timer_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *ce = dev_id; + + WARN_ON(!(readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_STATUS) & BIT(0))); + + /* clear timer0 interrupt */ + writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS); + + ce->event_handler(ce); + + return IRQ_HANDLED; +} + +/* read 64-bit timer counter */ +static cycle_t sirfsoc_timer_read(struct clocksource *cs) +{ + u64 cycles; + + /* latch the 64-bit timer counter */ + writel_relaxed(SIRFSOC_TIMER_LATCH_BIT, sirfsoc_timer_base + SIRFSOC_TIMER_LATCH); + cycles = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_HI); + cycles = (cycles << 32) | readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO); + + return cycles; +} + +static int sirfsoc_timer_set_next_event(unsigned long delta, + struct clock_event_device *ce) +{ + unsigned long now, next; + + writel_relaxed(SIRFSOC_TIMER_LATCH_BIT, sirfsoc_timer_base + SIRFSOC_TIMER_LATCH); + now = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO); + next = now + delta; + writel_relaxed(next, sirfsoc_timer_base + SIRFSOC_TIMER_MATCH_0); + writel_relaxed(SIRFSOC_TIMER_LATCH_BIT, sirfsoc_timer_base + SIRFSOC_TIMER_LATCH); + now = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_LATCHED_LO); + + return next - now > delta ? -ETIME : 0; +} + +static void sirfsoc_timer_set_mode(enum clock_event_mode mode, + struct clock_event_device *ce) +{ + u32 val = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN); + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + WARN_ON(1); + break; + case CLOCK_EVT_MODE_ONESHOT: + writel_relaxed(val | BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN); + break; + case CLOCK_EVT_MODE_SHUTDOWN: + writel_relaxed(val & ~BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_INT_EN); + break; + case CLOCK_EVT_MODE_UNUSED: + case CLOCK_EVT_MODE_RESUME: + break; + } +} + +static struct clock_event_device sirfsoc_clockevent = { + .name = "sirfsoc_clockevent", + .rating = 200, + .features = CLOCK_EVT_FEAT_ONESHOT, + .set_mode = sirfsoc_timer_set_mode, + .set_next_event = sirfsoc_timer_set_next_event, +}; + +static struct clocksource sirfsoc_clocksource = { + .name = "sirfsoc_clocksource", + .rating = 200, + .mask = CLOCKSOURCE_MASK(64), + .flags = CLOCK_SOURCE_IS_CONTINUOUS, + .read = sirfsoc_timer_read, +}; + +static struct irqaction sirfsoc_timer_irq = { + .name = "sirfsoc_timer0", + .flags = IRQF_TIMER, + .irq = 0, + .handler = sirfsoc_timer_interrupt, + .dev_id = &sirfsoc_clockevent, +}; + +/* Overwrite weak default sched_clock with more precise one */ +unsigned long long notrace sched_clock(void) +{ + static int is_mapped = 0; + + /* + * sched_clock is called earlier than .init of sys_timer + * if we map timer memory in .init of sys_timer, system + * will panic due to illegal memory access + */ + if(!is_mapped) { + sirfsoc_of_timer_map(); + is_mapped = 1; + } + + return sirfsoc_timer_read(NULL) * (NSEC_PER_SEC / CLOCK_TICK_RATE); +} + +static void __init sirfsoc_clockevent_init(void) +{ + clockevents_calc_mult_shift(&sirfsoc_clockevent, CLOCK_TICK_RATE, 60); + + sirfsoc_clockevent.max_delta_ns = + clockevent_delta2ns(-2, &sirfsoc_clockevent); + sirfsoc_clockevent.min_delta_ns = + clockevent_delta2ns(2, &sirfsoc_clockevent); + + sirfsoc_clockevent.cpumask = cpumask_of(0); + clockevents_register_device(&sirfsoc_clockevent); +} + +/* initialize the kernel jiffy timer source */ +static void __init sirfsoc_timer_init(void) +{ + unsigned long rate; + + /* timer's input clock is io clock */ + struct clk *clk = clk_get_sys("io", NULL); + + BUG_ON(IS_ERR(clk)); + + rate = clk_get_rate(clk); + + BUG_ON(rate < CLOCK_TICK_RATE); + BUG_ON(rate % CLOCK_TICK_RATE); + + writel_relaxed(rate / CLOCK_TICK_RATE / 2 - 1, sirfsoc_timer_base + SIRFSOC_TIMER_DIV); + writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_LO); + writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_HI); + writel_relaxed(BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_STATUS); + + BUG_ON(clocksource_register_hz(&sirfsoc_clocksource, CLOCK_TICK_RATE)); + + BUG_ON(setup_irq(sirfsoc_timer_irq.irq, &sirfsoc_timer_irq)); + + sirfsoc_clockevent_init(); +} + +static struct of_device_id timer_ids[] = { + { .compatible = "sirf,prima2-tick" }, + {}, +}; + +static void __init sirfsoc_of_timer_map(void) +{ + struct device_node *np; + const unsigned int *intspec; + + np = of_find_matching_node(NULL, timer_ids); + if (!np) + panic("unable to find compatible timer node in dtb\n"); + sirfsoc_timer_base = of_iomap(np, 0); + if (!sirfsoc_timer_base) + panic("unable to map timer cpu registers\n"); + + /* Get the interrupts property */ + intspec = of_get_property(np, "interrupts", NULL); + BUG_ON(!intspec); + sirfsoc_timer_irq.irq = be32_to_cpup(intspec); + + of_node_put(np); +} + +struct sys_timer sirfsoc_timer = { + .init = sirfsoc_timer_init, +}; |