2 * Copyright (C) 2012 Broadcom Corporation
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License as
6 * published by the Free Software Foundation version 2.
8 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
9 * kind, whether express or implied; without even the implied warranty
10 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 * GNU General Public License for more details.
14 #include <linux/init.h>
15 #include <linux/irq.h>
16 #include <linux/interrupt.h>
17 #include <linux/jiffies.h>
18 #include <linux/clockchips.h>
19 #include <linux/types.h>
22 #include <asm/mach/time.h>
25 #include <linux/of_address.h>
26 #include <linux/of_irq.h>
29 #define KONA_GPTIMER_STCS_OFFSET 0x00000000
30 #define KONA_GPTIMER_STCLO_OFFSET 0x00000004
31 #define KONA_GPTIMER_STCHI_OFFSET 0x00000008
32 #define KONA_GPTIMER_STCM0_OFFSET 0x0000000C
34 #define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT 0
35 #define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT 4
37 struct kona_bcm_timers {
39 void __iomem *tmr_regs;
42 static struct kona_bcm_timers timers;
44 static u32 arch_timer_rate;
47 * We use the peripheral timers for system tick, the cpu global timer for
50 static void kona_timer_disable_and_clear(void __iomem *base)
55 * clear and disable interrupts
56 * We are using compare/match register 0 for our system interrupts
58 reg = readl(base + KONA_GPTIMER_STCS_OFFSET);
60 /* Clear compare (0) interrupt */
61 reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;
63 reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
65 writel(reg, base + KONA_GPTIMER_STCS_OFFSET);
70 kona_timer_get_counter(void *timer_base, uint32_t *msw, uint32_t *lsw)
72 void __iomem *base = IOMEM(timer_base);
76 * Read 64-bit free running counter
79 * 3. Read hi-word again
81 * if new hi-word is not equal to previously read hi-word, then
84 * if new hi-word is equal to previously read hi-word then stop.
87 while (--loop_limit) {
88 *msw = readl(base + KONA_GPTIMER_STCHI_OFFSET);
89 *lsw = readl(base + KONA_GPTIMER_STCLO_OFFSET);
90 if (*msw == readl(base + KONA_GPTIMER_STCHI_OFFSET))
94 pr_err("bcm_kona_timer: getting counter failed.\n");
95 pr_err(" Timer will be impacted\n");
101 static void __init kona_timers_init(struct device_node *node)
105 if (!of_property_read_u32(node, "clock-frequency", &freq))
106 arch_timer_rate = freq;
108 panic("clock-frequency not set in the .dts file");
110 /* Setup IRQ numbers */
111 timers.tmr_irq = irq_of_parse_and_map(node, 0);
113 /* Setup IO addresses */
114 timers.tmr_regs = of_iomap(node, 0);
116 kona_timer_disable_and_clear(timers.tmr_regs);
119 static int kona_timer_set_next_event(unsigned long clc,
120 struct clock_event_device *unused)
123 * timer (0) is disabled by the timer interrupt already
124 * so, here we reload the next event value and re-enable
127 * This way, we are potentially losing the time between
128 * timer-interrupt->set_next_event. CPU local timers, when
129 * they come in should get rid of skew.
135 kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
137 /* Load the "next" event tick value */
138 writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);
141 reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
142 reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
143 writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
148 static void kona_timer_set_mode(enum clock_event_mode mode,
149 struct clock_event_device *unused)
152 case CLOCK_EVT_MODE_ONESHOT:
153 /* by default mode is one shot don't do any thing */
155 case CLOCK_EVT_MODE_UNUSED:
156 case CLOCK_EVT_MODE_SHUTDOWN:
158 kona_timer_disable_and_clear(timers.tmr_regs);
162 static struct clock_event_device kona_clockevent_timer = {
164 .features = CLOCK_EVT_FEAT_ONESHOT,
165 .set_next_event = kona_timer_set_next_event,
166 .set_mode = kona_timer_set_mode
169 static void __init kona_timer_clockevents_init(void)
171 kona_clockevent_timer.cpumask = cpumask_of(0);
172 clockevents_config_and_register(&kona_clockevent_timer,
173 arch_timer_rate, 6, 0xffffffff);
176 static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)
178 struct clock_event_device *evt = &kona_clockevent_timer;
180 kona_timer_disable_and_clear(timers.tmr_regs);
181 evt->event_handler(evt);
185 static struct irqaction kona_timer_irq = {
186 .name = "Kona Timer Tick",
188 .handler = kona_timer_interrupt,
191 static void __init kona_timer_init(struct device_node *node)
193 kona_timers_init(node);
194 kona_timer_clockevents_init();
195 setup_irq(timers.tmr_irq, &kona_timer_irq);
196 kona_timer_set_next_event((arch_timer_rate / HZ), NULL);
199 CLOCKSOURCE_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);
201 * bcm,kona-timer is deprecated by brcm,kona-timer
202 * being kept here for driver compatibility
204 CLOCKSOURCE_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);