1/*
  2 * arch/arm/mach-netx/time.c
  3 *
  4 * Copyright (c) 2005 Sascha Hauer <s.hauer@pengutronix.de>, Pengutronix
  5 *
  6 * This program is free software; you can redistribute it and/or modify
  7 * it under the terms of the GNU General Public License version 2
  8 * as published by the Free Software Foundation.
  9 *
 10 * This program is distributed in the hope that it will be useful,
 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 13 * GNU General Public License for more details.
 14 *
 15 * You should have received a copy of the GNU General Public License
 16 * along with this program; if not, write to the Free Software
 17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 18 */
 19
 20#include <linux/init.h>
 21#include <linux/interrupt.h>
 22#include <linux/irq.h>
 23#include <linux/clocksource.h>
 24#include <linux/clockchips.h>
 25#include <linux/io.h>
 26
 27#include <mach/hardware.h>
 28#include <asm/mach/time.h>
 29#include <mach/netx-regs.h>
 30
 31#define NETX_CLOCK_FREQ 100000000
 32#define NETX_LATCH DIV_ROUND_CLOSEST(NETX_CLOCK_FREQ, HZ)
 33
 34#define TIMER_CLOCKEVENT 0
 35#define TIMER_CLOCKSOURCE 1
 36
 37static inline void timer_shutdown(struct clock_event_device *evt)
 38{
 39	/* disable timer */
 40	writel(0, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKEVENT));
 41}
 42
 43static int netx_shutdown(struct clock_event_device *evt)
 44{
 45	timer_shutdown(evt);
 46
 47	return 0;
 48}
 49
 50static int netx_set_oneshot(struct clock_event_device *evt)
 51{
 52	u32 tmode = NETX_GPIO_COUNTER_CTRL_IRQ_EN | NETX_GPIO_COUNTER_CTRL_RUN;
 53
 54	timer_shutdown(evt);
 55	writel(0, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKEVENT));
 56	writel(tmode, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKEVENT));
 57
 58	return 0;
 59}
 60
 61static int netx_set_periodic(struct clock_event_device *evt)
 62{
 63	u32 tmode = NETX_GPIO_COUNTER_CTRL_RST_EN |
 64		    NETX_GPIO_COUNTER_CTRL_IRQ_EN | NETX_GPIO_COUNTER_CTRL_RUN;
 65
 66	timer_shutdown(evt);
 67	writel(NETX_LATCH, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKEVENT));
 68	writel(tmode, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKEVENT));
 69
 70	return 0;
 71}
 72
 73static int netx_set_next_event(unsigned long evt,
 74		struct clock_event_device *clk)
 75{
 76	writel(0 - evt, NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKEVENT));
 77	return 0;
 78}
 79
 80static struct clock_event_device netx_clockevent = {
 81	.name = "netx-timer" __stringify(TIMER_CLOCKEVENT),
 82	.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
 83	.set_next_event = netx_set_next_event,
 84	.set_state_shutdown = netx_shutdown,
 85	.set_state_periodic = netx_set_periodic,
 86	.set_state_oneshot = netx_set_oneshot,
 87	.tick_resume = netx_shutdown,
 88};
 89
 90/*
 91 * IRQ handler for the timer
 92 */
 93static irqreturn_t
 94netx_timer_interrupt(int irq, void *dev_id)
 95{
 96	struct clock_event_device *evt = &netx_clockevent;
 97
 98	/* acknowledge interrupt */
 99	writel(COUNTER_BIT(0), NETX_GPIO_IRQ);
100
101	evt->event_handler(evt);
102
103	return IRQ_HANDLED;
104}
105
106static struct irqaction netx_timer_irq = {
107	.name		= "NetX Timer Tick",
108	.flags		= IRQF_TIMER | IRQF_IRQPOLL,
109	.handler	= netx_timer_interrupt,
110};
111
112/*
113 * Set up timer interrupt
114 */
115void __init netx_timer_init(void)
116{
117	/* disable timer initially */
118	writel(0, NETX_GPIO_COUNTER_CTRL(0));
119
120	/* Reset the timer value to zero */
121	writel(0, NETX_GPIO_COUNTER_CURRENT(0));
122
123	writel(NETX_LATCH, NETX_GPIO_COUNTER_MAX(0));
124
125	/* acknowledge interrupt */
126	writel(COUNTER_BIT(0), NETX_GPIO_IRQ);
127
128	/* Enable the interrupt in the specific timer
129	 * register and start timer
130	 */
131	writel(COUNTER_BIT(0), NETX_GPIO_IRQ_ENABLE);
132	writel(NETX_GPIO_COUNTER_CTRL_IRQ_EN | NETX_GPIO_COUNTER_CTRL_RUN,
133			NETX_GPIO_COUNTER_CTRL(0));
134
135	setup_irq(NETX_IRQ_TIMER0, &netx_timer_irq);
136
137	/* Setup timer one for clocksource */
138	writel(0, NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKSOURCE));
139	writel(0, NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKSOURCE));
140	writel(0xffffffff, NETX_GPIO_COUNTER_MAX(TIMER_CLOCKSOURCE));
141
142	writel(NETX_GPIO_COUNTER_CTRL_RUN,
143			NETX_GPIO_COUNTER_CTRL(TIMER_CLOCKSOURCE));
144
145	clocksource_mmio_init(NETX_GPIO_COUNTER_CURRENT(TIMER_CLOCKSOURCE),
146		"netx_timer", NETX_CLOCK_FREQ, 200, 32, clocksource_mmio_readl_up);
147
148	/* with max_delta_ns >= delta2ns(0x800) the system currently runs fine.
149	 * Adding some safety ... */
150	netx_clockevent.cpumask = cpumask_of(0);
151	clockevents_config_and_register(&netx_clockevent, NETX_CLOCK_FREQ,
152					0xa00, 0xfffffffe);
153}