| /* |
| * arch/arm/mach-vt8500/timer.c |
| * |
| * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz> |
| * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License as published by |
| * the Free Software Foundation; either version 2 of the License, or |
| * (at your option) any later version. |
| * |
| * This program is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| * GNU General Public License for more details. |
| * |
| * You should have received a copy of the GNU General Public License |
| * along with this program; if not, write to the Free Software |
| * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| */ |
| |
| /* |
| * This file is copied and modified from the original timer.c provided by |
| * Alexey Charkov. Minor changes have been made for Device Tree Support. |
| */ |
| |
| #include <linux/io.h> |
| #include <linux/irq.h> |
| #include <linux/interrupt.h> |
| #include <linux/clocksource.h> |
| #include <linux/clockchips.h> |
| #include <linux/delay.h> |
| #include <asm/mach/time.h> |
| |
| #include <linux/of.h> |
| #include <linux/of_address.h> |
| #include <linux/of_irq.h> |
| |
| #define VT8500_TIMER_OFFSET 0x0100 |
| #define VT8500_TIMER_HZ 3000000 |
| #define TIMER_MATCH_VAL 0x0000 |
| #define TIMER_COUNT_VAL 0x0010 |
| #define TIMER_STATUS_VAL 0x0014 |
| #define TIMER_IER_VAL 0x001c /* interrupt enable */ |
| #define TIMER_CTRL_VAL 0x0020 |
| #define TIMER_AS_VAL 0x0024 /* access status */ |
| #define TIMER_COUNT_R_ACTIVE (1 << 5) /* not ready for read */ |
| #define TIMER_COUNT_W_ACTIVE (1 << 4) /* not ready for write */ |
| #define TIMER_MATCH_W_ACTIVE (1 << 0) /* not ready for write */ |
| |
| #define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t) |
| |
| #define MIN_OSCR_DELTA 16 |
| |
| static void __iomem *regbase; |
| |
| static cycle_t vt8500_timer_read(struct clocksource *cs) |
| { |
| int loops = msecs_to_loops(10); |
| writel(3, regbase + TIMER_CTRL_VAL); |
| while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE) |
| && --loops) |
| cpu_relax(); |
| return readl(regbase + TIMER_COUNT_VAL); |
| } |
| |
| static struct clocksource clocksource = { |
| .name = "vt8500_timer", |
| .rating = 200, |
| .read = vt8500_timer_read, |
| .mask = CLOCKSOURCE_MASK(32), |
| .flags = CLOCK_SOURCE_IS_CONTINUOUS, |
| }; |
| |
| static int vt8500_timer_set_next_event(unsigned long cycles, |
| struct clock_event_device *evt) |
| { |
| int loops = msecs_to_loops(10); |
| cycle_t alarm = clocksource.read(&clocksource) + cycles; |
| while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE) |
| && --loops) |
| cpu_relax(); |
| writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL); |
| |
| if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA) |
| return -ETIME; |
| |
| writel(1, regbase + TIMER_IER_VAL); |
| |
| return 0; |
| } |
| |
| static void vt8500_timer_set_mode(enum clock_event_mode mode, |
| struct clock_event_device *evt) |
| { |
| switch (mode) { |
| case CLOCK_EVT_MODE_RESUME: |
| case CLOCK_EVT_MODE_PERIODIC: |
| break; |
| case CLOCK_EVT_MODE_ONESHOT: |
| case CLOCK_EVT_MODE_UNUSED: |
| case CLOCK_EVT_MODE_SHUTDOWN: |
| writel(readl(regbase + TIMER_CTRL_VAL) | 1, |
| regbase + TIMER_CTRL_VAL); |
| writel(0, regbase + TIMER_IER_VAL); |
| break; |
| } |
| } |
| |
| static struct clock_event_device clockevent = { |
| .name = "vt8500_timer", |
| .features = CLOCK_EVT_FEAT_ONESHOT, |
| .rating = 200, |
| .set_next_event = vt8500_timer_set_next_event, |
| .set_mode = vt8500_timer_set_mode, |
| }; |
| |
| static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id) |
| { |
| struct clock_event_device *evt = dev_id; |
| writel(0xf, regbase + TIMER_STATUS_VAL); |
| evt->event_handler(evt); |
| |
| return IRQ_HANDLED; |
| } |
| |
| static struct irqaction irq = { |
| .name = "vt8500_timer", |
| .flags = IRQF_TIMER | IRQF_IRQPOLL, |
| .handler = vt8500_timer_interrupt, |
| .dev_id = &clockevent, |
| }; |
| |
| static void __init vt8500_timer_init(struct device_node *np) |
| { |
| int timer_irq; |
| |
| regbase = of_iomap(np, 0); |
| if (!regbase) { |
| pr_err("%s: Missing iobase description in Device Tree\n", |
| __func__); |
| return; |
| } |
| timer_irq = irq_of_parse_and_map(np, 0); |
| if (!timer_irq) { |
| pr_err("%s: Missing irq description in Device Tree\n", |
| __func__); |
| return; |
| } |
| |
| writel(1, regbase + TIMER_CTRL_VAL); |
| writel(0xf, regbase + TIMER_STATUS_VAL); |
| writel(~0, regbase + TIMER_MATCH_VAL); |
| |
| if (clocksource_register_hz(&clocksource, VT8500_TIMER_HZ)) |
| pr_err("%s: vt8500_timer_init: clocksource_register failed for %s\n", |
| __func__, clocksource.name); |
| |
| clockevent.cpumask = cpumask_of(0); |
| |
| if (setup_irq(timer_irq, &irq)) |
| pr_err("%s: setup_irq failed for %s\n", __func__, |
| clockevent.name); |
| clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ, |
| MIN_OSCR_DELTA * 2, 0xf0000000); |
| } |
| |
| CLOCKSOURCE_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init); |