2 * Moschip MCS814x timer routines
4 * Copyright (C) 2012, Florian Fainelli <florian@openwrt.org>
8 #include <linux/kernel.h>
9 #include <linux/interrupt.h>
10 #include <linux/time.h>
11 #include <linux/timex.h>
12 #include <linux/irq.h>
13 #include <linux/err.h>
14 #include <linux/clk.h>
17 #include <linux/of_address.h>
19 #include <asm/mach/time.h>
20 #include <mach/mcs814x.h>
22 /* Timer block registers */
23 #define TIMER_VAL 0x00
24 #define TIMER_CTL 0x04
25 #define TIMER_CTL_EN 0x01
26 #define TIMER_CTL_DBG 0x02
28 static u32 last_reload
;
29 static u32 timer_correct
;
30 static u32 clock_rate
;
31 static u32 timer_reload_value
;
32 static void __iomem
*mcs814x_timer_base
;
34 static inline unsigned long ticks2usecs(u32 x
)
36 return x
/ (clock_rate
/ 1000000);
40 * Returns number of ms since last clock interrupt. Note that interrupts
41 * will have been disabled by do_gettimeoffset()
43 static unsigned long mcs814x_gettimeoffset(void)
45 u32 ticks
= readl_relaxed(mcs814x_timer_base
+ TIMER_VAL
);
47 if (ticks
< last_reload
)
48 return ticks2usecs(ticks
+ (u32
)(0xffffffff - last_reload
));
50 return ticks2usecs(ticks
- last_reload
);
54 static irqreturn_t
mcs814x_timer_interrupt(int irq
, void *dev_id
)
56 u32 count
= readl_relaxed(mcs814x_timer_base
+ TIMER_VAL
);
58 /* take into account delay up to this moment */
59 last_reload
= count
+ timer_correct
+ timer_reload_value
;
61 if (last_reload
< timer_reload_value
) {
62 last_reload
= timer_reload_value
;
64 if (timer_correct
== 0)
65 timer_correct
= readl_relaxed(mcs814x_timer_base
+ TIMER_VAL
) - count
;
67 writel_relaxed(last_reload
, mcs814x_timer_base
+ TIMER_VAL
);
74 static struct irqaction mcs814x_timer_irq
= {
75 .name
= "mcs814x-timer",
76 .flags
= IRQF_DISABLED
| IRQF_TIMER
| IRQF_IRQPOLL
,
77 .handler
= mcs814x_timer_interrupt
,
80 static struct of_device_id mcs814x_timer_ids
[] = {
81 { .compatible
= "moschip,mcs814x-timer" },
85 static void __init
mcs814x_of_timer_init(void)
87 struct device_node
*np
;
88 const unsigned int *intspec
;
90 np
= of_find_matching_node(NULL
, mcs814x_timer_ids
);
92 panic("unable to find compatible timer node in dtb");
94 mcs814x_timer_base
= of_iomap(np
, 0);
95 if (!mcs814x_timer_base
)
96 panic("unable to remap timer cpu registers");
98 intspec
= of_get_property(np
, "interrupts", NULL
);
100 panic("no interrupts property for timer");
102 mcs814x_timer_irq
.irq
= be32_to_cpup(intspec
);
105 static void __init
mcs814x_timer_init(void)
109 clk
= clk_get_sys("timer0", NULL
);
110 if (IS_ERR_OR_NULL(clk
))
111 panic("unable to get timer0 clock");
113 clock_rate
= clk_get_rate(clk
);
116 mcs814x_of_timer_init();
118 pr_info("Timer frequency: %d (kHz)\n", clock_rate
/ 1000);
120 timer_reload_value
= 0xffffffff - (clock_rate
/ HZ
);
123 writel_relaxed(~TIMER_CTL_EN
, mcs814x_timer_base
+ TIMER_CTL
);
124 writel_relaxed(timer_reload_value
, mcs814x_timer_base
+ TIMER_VAL
);
125 last_reload
= timer_reload_value
;
127 setup_irq(mcs814x_timer_irq
.irq
, &mcs814x_timer_irq
);
128 /* enable timer, stop timer in debug mode */
129 writel_relaxed(TIMER_CTL_EN
| TIMER_CTL_DBG
,
130 mcs814x_timer_base
+ TIMER_CTL
);
133 struct sys_timer mcs814x_timer
= {
134 .init
= mcs814x_timer_init
,
135 .offset
= mcs814x_gettimeoffset
,