diff options
Diffstat (limited to 'drivers/clocksource/timer-vt8500.c')
| -rw-r--r-- | drivers/clocksource/timer-vt8500.c | 168 |
1 files changed, 168 insertions, 0 deletions
diff --git a/drivers/clocksource/timer-vt8500.c b/drivers/clocksource/timer-vt8500.c new file mode 100644 index 000000000..e0f7489cf --- /dev/null +++ b/drivers/clocksource/timer-vt8500.c @@ -0,0 +1,168 @@ +/* + * 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 <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 u64 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); + u64 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 int vt8500_shutdown(struct clock_event_device *evt) +{ + writel(readl(regbase + TIMER_CTRL_VAL) | 1, regbase + TIMER_CTRL_VAL); + writel(0, regbase + TIMER_IER_VAL); + return 0; +} + +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_state_shutdown = vt8500_shutdown, + .set_state_oneshot = vt8500_shutdown, +}; + +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 int __init vt8500_timer_init(struct device_node *np) +{ + int timer_irq, ret; + + regbase = of_iomap(np, 0); + if (!regbase) { + pr_err("%s: Missing iobase description in Device Tree\n", + __func__); + return -ENXIO; + } + + timer_irq = irq_of_parse_and_map(np, 0); + if (!timer_irq) { + pr_err("%s: Missing irq description in Device Tree\n", + __func__); + return -EINVAL; + } + + writel(1, regbase + TIMER_CTRL_VAL); + writel(0xf, regbase + TIMER_STATUS_VAL); + writel(~0, regbase + TIMER_MATCH_VAL); + + ret = clocksource_register_hz(&clocksource, VT8500_TIMER_HZ); + if (ret) { + pr_err("%s: vt8500_timer_init: clocksource_register failed for %s\n", + __func__, clocksource.name); + return ret; + } + + clockevent.cpumask = cpumask_of(0); + + ret = setup_irq(timer_irq, &irq); + if (ret) { + pr_err("%s: setup_irq failed for %s\n", __func__, + clockevent.name); + return ret; + } + + clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ, + MIN_OSCR_DELTA * 2, 0xf0000000); + + return 0; +} + +TIMER_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init); |