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Diffstat (limited to '')
| -rw-r--r-- | drivers/clocksource/pxa_timer.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/drivers/clocksource/pxa_timer.c b/drivers/clocksource/pxa_timer.c new file mode 100644 index 000000000..08cd6eaf3 --- /dev/null +++ b/drivers/clocksource/pxa_timer.c @@ -0,0 +1,236 @@ +/* + * arch/arm/mach-pxa/time.c + * + * PXA clocksource, clockevents, and OST interrupt handlers. + * Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>. + * + * Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001 + * by MontaVista Software, Inc. (Nico, your code rocks!) + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#include <linux/kernel.h> +#include <linux/init.h> +#include <linux/interrupt.h> +#include <linux/clk.h> +#include <linux/clockchips.h> +#include <linux/of_address.h> +#include <linux/of_irq.h> +#include <linux/sched/clock.h> +#include <linux/sched_clock.h> + +#include <clocksource/pxa.h> + +#include <asm/div64.h> + +#define OSMR0 0x00 /* OS Timer 0 Match Register */ +#define OSMR1 0x04 /* OS Timer 1 Match Register */ +#define OSMR2 0x08 /* OS Timer 2 Match Register */ +#define OSMR3 0x0C /* OS Timer 3 Match Register */ + +#define OSCR 0x10 /* OS Timer Counter Register */ +#define OSSR 0x14 /* OS Timer Status Register */ +#define OWER 0x18 /* OS Timer Watchdog Enable Register */ +#define OIER 0x1C /* OS Timer Interrupt Enable Register */ + +#define OSSR_M3 (1 << 3) /* Match status channel 3 */ +#define OSSR_M2 (1 << 2) /* Match status channel 2 */ +#define OSSR_M1 (1 << 1) /* Match status channel 1 */ +#define OSSR_M0 (1 << 0) /* Match status channel 0 */ + +#define OIER_E0 (1 << 0) /* Interrupt enable channel 0 */ + +/* + * This is PXA's sched_clock implementation. This has a resolution + * of at least 308 ns and a maximum value of 208 days. + * + * The return value is guaranteed to be monotonic in that range as + * long as there is always less than 582 seconds between successive + * calls to sched_clock() which should always be the case in practice. + */ + +#define timer_readl(reg) readl_relaxed(timer_base + (reg)) +#define timer_writel(val, reg) writel_relaxed((val), timer_base + (reg)) + +static void __iomem *timer_base; + +static u64 notrace pxa_read_sched_clock(void) +{ + return timer_readl(OSCR); +} + + +#define MIN_OSCR_DELTA 16 + +static irqreturn_t +pxa_ost0_interrupt(int irq, void *dev_id) +{ + struct clock_event_device *c = dev_id; + + /* Disarm the compare/match, signal the event. */ + timer_writel(timer_readl(OIER) & ~OIER_E0, OIER); + timer_writel(OSSR_M0, OSSR); + c->event_handler(c); + + return IRQ_HANDLED; +} + +static int +pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev) +{ + unsigned long next, oscr; + + timer_writel(timer_readl(OIER) | OIER_E0, OIER); + next = timer_readl(OSCR) + delta; + timer_writel(next, OSMR0); + oscr = timer_readl(OSCR); + + return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0; +} + +static int pxa_osmr0_shutdown(struct clock_event_device *evt) +{ + /* initializing, released, or preparing for suspend */ + timer_writel(timer_readl(OIER) & ~OIER_E0, OIER); + timer_writel(OSSR_M0, OSSR); + return 0; +} + +#ifdef CONFIG_PM +static unsigned long osmr[4], oier, oscr; + +static void pxa_timer_suspend(struct clock_event_device *cedev) +{ + osmr[0] = timer_readl(OSMR0); + osmr[1] = timer_readl(OSMR1); + osmr[2] = timer_readl(OSMR2); + osmr[3] = timer_readl(OSMR3); + oier = timer_readl(OIER); + oscr = timer_readl(OSCR); +} + +static void pxa_timer_resume(struct clock_event_device *cedev) +{ + /* + * Ensure that we have at least MIN_OSCR_DELTA between match + * register 0 and the OSCR, to guarantee that we will receive + * the one-shot timer interrupt. We adjust OSMR0 in preference + * to OSCR to guarantee that OSCR is monotonically incrementing. + */ + if (osmr[0] - oscr < MIN_OSCR_DELTA) + osmr[0] += MIN_OSCR_DELTA; + + timer_writel(osmr[0], OSMR0); + timer_writel(osmr[1], OSMR1); + timer_writel(osmr[2], OSMR2); + timer_writel(osmr[3], OSMR3); + timer_writel(oier, OIER); + timer_writel(oscr, OSCR); +} +#else +#define pxa_timer_suspend NULL +#define pxa_timer_resume NULL +#endif + +static struct clock_event_device ckevt_pxa_osmr0 = { + .name = "osmr0", + .features = CLOCK_EVT_FEAT_ONESHOT, + .rating = 200, + .set_next_event = pxa_osmr0_set_next_event, + .set_state_shutdown = pxa_osmr0_shutdown, + .set_state_oneshot = pxa_osmr0_shutdown, + .suspend = pxa_timer_suspend, + .resume = pxa_timer_resume, +}; + +static struct irqaction pxa_ost0_irq = { + .name = "ost0", + .flags = IRQF_TIMER | IRQF_IRQPOLL, + .handler = pxa_ost0_interrupt, + .dev_id = &ckevt_pxa_osmr0, +}; + +static int __init pxa_timer_common_init(int irq, unsigned long clock_tick_rate) +{ + int ret; + + timer_writel(0, OIER); + timer_writel(OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3, OSSR); + + sched_clock_register(pxa_read_sched_clock, 32, clock_tick_rate); + + ckevt_pxa_osmr0.cpumask = cpumask_of(0); + + ret = setup_irq(irq, &pxa_ost0_irq); + if (ret) { + pr_err("Failed to setup irq\n"); + return ret; + } + + ret = clocksource_mmio_init(timer_base + OSCR, "oscr0", clock_tick_rate, 200, + 32, clocksource_mmio_readl_up); + if (ret) { + pr_err("Failed to init clocksource\n"); + return ret; + } + + clockevents_config_and_register(&ckevt_pxa_osmr0, clock_tick_rate, + MIN_OSCR_DELTA * 2, 0x7fffffff); + + return 0; +} + +static int __init pxa_timer_dt_init(struct device_node *np) +{ + struct clk *clk; + int irq, ret; + + /* timer registers are shared with watchdog timer */ + timer_base = of_iomap(np, 0); + if (!timer_base) { + pr_err("%s: unable to map resource\n", np->name); + return -ENXIO; + } + + clk = of_clk_get(np, 0); + if (IS_ERR(clk)) { + pr_crit("%s: unable to get clk\n", np->name); + return PTR_ERR(clk); + } + + ret = clk_prepare_enable(clk); + if (ret) { + pr_crit("Failed to prepare clock\n"); + return ret; + } + + /* we are only interested in OS-timer0 irq */ + irq = irq_of_parse_and_map(np, 0); + if (irq <= 0) { + pr_crit("%s: unable to parse OS-timer0 irq\n", np->name); + return -EINVAL; + } + + return pxa_timer_common_init(irq, clk_get_rate(clk)); +} +TIMER_OF_DECLARE(pxa_timer, "marvell,pxa-timer", pxa_timer_dt_init); + +/* + * Legacy timer init for non device-tree boards. + */ +void __init pxa_timer_nodt_init(int irq, void __iomem *base) +{ + struct clk *clk; + + timer_base = base; + clk = clk_get(NULL, "OSTIMER0"); + if (clk && !IS_ERR(clk)) { + clk_prepare_enable(clk); + pxa_timer_common_init(irq, clk_get_rate(clk)); + } else { + pr_crit("%s: unable to get clk\n", __func__); + } +} |