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>
18 #include <linux/of_irq.h>
20 #include <asm/mach/time.h>
21 #include <mach/mcs814x.h>
23 /* Timer block registers */
24 #define TIMER_VAL 0x00
25 #define TIMER_CTL 0x04
26 #define TIMER_CTL_EN 0x01
27 #define TIMER_CTL_DBG 0x02
29 static u32 last_reload
;
30 static u32 timer_correct
;
31 static u32 clock_rate
;
32 static u32 timer_reload_value
;
33 static void __iomem
*mcs814x_timer_base
;
35 static inline u32
ticks2usecs(u32 x
)
37 return x
/ (clock_rate
/ 1000000);
41 * Returns number of ms since last clock interrupt. Note that interrupts
42 * will have been disabled by do_gettimeoffset()
44 static u32
mcs814x_gettimeoffset(void)
46 u32 ticks
= readl_relaxed(mcs814x_timer_base
+ TIMER_VAL
);
48 if (ticks
< last_reload
)
49 return ticks2usecs(ticks
+ (u32
)(0xffffffff - last_reload
));
51 return ticks2usecs(ticks
- last_reload
);
55 static irqreturn_t
mcs814x_timer_interrupt(int irq
, void *dev_id
)
57 u32 count
= readl_relaxed(mcs814x_timer_base
+ TIMER_VAL
);
59 /* take into account delay up to this moment */
60 last_reload
= count
+ timer_correct
+ timer_reload_value
;
62 if (last_reload
< timer_reload_value
) {
63 last_reload
= timer_reload_value
;
65 if (timer_correct
== 0)
66 timer_correct
= readl_relaxed(mcs814x_timer_base
+ TIMER_VAL
) - count
;
68 writel_relaxed(last_reload
, mcs814x_timer_base
+ TIMER_VAL
);
75 static struct of_device_id mcs814x_timer_ids
[] = {
76 { .compatible
= "moschip,mcs814x-timer" },
80 static int __init
mcs814x_of_timer_init(void)
82 struct device_node
*np
;
85 np
= of_find_matching_node(NULL
, mcs814x_timer_ids
);
87 panic("unable to find compatible timer node in dtb");
89 mcs814x_timer_base
= of_iomap(np
, 0);
90 if (!mcs814x_timer_base
)
91 panic("unable to remap timer cpu registers");
93 irq
= irq_of_parse_and_map(np
, 0);
95 panic("no interrupts property/mapping failed for timer");
100 void __init
mcs814x_timer_init(void)
105 arch_gettimeoffset
= mcs814x_gettimeoffset
;
107 clk
= clk_get_sys("timer0", NULL
);
108 if (IS_ERR_OR_NULL(clk
))
109 panic("unable to get timer0 clock");
111 clock_rate
= clk_get_rate(clk
);
113 irq
= mcs814x_of_timer_init();
115 pr_info("Timer frequency: %d (kHz)\n", clock_rate
/ 1000);
117 timer_reload_value
= 0xffffffff - (clock_rate
/ HZ
);
120 writel_relaxed(~TIMER_CTL_EN
, mcs814x_timer_base
+ TIMER_CTL
);
121 writel_relaxed(timer_reload_value
, mcs814x_timer_base
+ TIMER_VAL
);
122 last_reload
= timer_reload_value
;
124 if (request_irq(irq
, mcs814x_timer_interrupt
,
125 IRQF_DISABLED
| IRQF_TIMER
| IRQF_IRQPOLL
,
126 "mcs814x-timer", NULL
))
127 panic("unable to request timer0 irq %d", irq
);
129 /* enable timer, stop timer in debug mode */
130 writel_relaxed(TIMER_CTL_EN
| TIMER_CTL_DBG
,
131 mcs814x_timer_base
+ TIMER_CTL
);