2 * arch/sh/kernel/timers/timer-cmt.c - CMT Timer Support
4 * Copyright (C) 2005 Yoshinori Sato
6 * This file is subject to the terms and conditions of the GNU General Public
7 * License. See the file "COPYING" in the main directory of this archive
11 #include <linux/init.h>
12 #include <linux/kernel.h>
13 #include <linux/interrupt.h>
14 #include <linux/seqlock.h>
15 #include <asm/timer.h>
19 #include <asm/clock.h>
21 #if defined(CONFIG_CPU_SUBTYPE_SH7619)
22 #define CMT_CMSTR 0xf84a0070
23 #define CMT_CMCSR_0 0xf84a0072
24 #define CMT_CMCNT_0 0xf84a0074
25 #define CMT_CMCOR_0 0xf84a0076
26 #define CMT_CMCSR_1 0xf84a0078
27 #define CMT_CMCNT_1 0xf84a007a
28 #define CMT_CMCOR_1 0xf84a007c
30 #define STBCR3 0xf80a0000
31 #define cmt_clock_enable() do { ctrl_outb(ctrl_inb(STBCR3) & ~0x10, STBCR3); } while(0)
32 #define CMT_CMCSR_INIT 0x0040
33 #define CMT_CMCSR_CALIB 0x0000
34 #elif defined(CONFIG_CPU_SUBTYPE_SH7206)
35 #define CMT_CMSTR 0xfffec000
36 #define CMT_CMCSR_0 0xfffec002
37 #define CMT_CMCNT_0 0xfffec004
38 #define CMT_CMCOR_0 0xfffec006
40 #define STBCR4 0xfffe040c
41 #define cmt_clock_enable() do { ctrl_outb(ctrl_inb(STBCR4) & ~0x04, STBCR4); } while(0)
42 #define CMT_CMCSR_INIT 0x0040
43 #define CMT_CMCSR_CALIB 0x0000
45 #error "Unknown CPU SUBTYPE"
48 static unsigned long cmt_timer_get_offset(void)
51 static unsigned short count_p
= 0xffff; /* for the first call after boot */
52 static unsigned long jiffies_p
= 0;
55 * cache volatile jiffies temporarily; we have IRQs turned off.
57 unsigned long jiffies_t
;
59 /* timer count may underflow right here */
60 count
= ctrl_inw(CMT_CMCOR_0
);
61 count
-= ctrl_inw(CMT_CMCNT_0
);
66 * avoiding timer inconsistencies (they are rare, but they happen)...
67 * there is one kind of problem that must be avoided here:
68 * 1. the timer counter underflows
71 if (jiffies_t
== jiffies_p
) {
72 if (count
> count_p
) {
74 if (ctrl_inw(CMT_CMCSR_0
) & 0x80) { /* Check CMF bit */
77 printk("%s (): hardware timer problem?\n",
82 jiffies_p
= jiffies_t
;
86 count
= ((LATCH
-1) - count
) * TICK_SIZE
;
87 count
= (count
+ LATCH
/2) / LATCH
;
92 static irqreturn_t
cmt_timer_interrupt(int irq
, void *dev_id
)
94 unsigned long timer_status
;
97 timer_status
= ctrl_inw(CMT_CMCSR_0
);
98 timer_status
&= ~0x80;
99 ctrl_outw(timer_status
, CMT_CMCSR_0
);
102 * Here we are in the timer irq handler. We just have irqs locally
103 * disabled but we don't know if the timer_bh is running on the other
104 * CPU. We need to avoid to SMP race with it. NOTE: we don' t need
105 * the irq version of write_lock because as just said we have irq
106 * locally disabled. -arca
108 write_seqlock(&xtime_lock
);
110 write_sequnlock(&xtime_lock
);
115 static struct irqaction cmt_irq
= {
117 .handler
= cmt_timer_interrupt
,
118 .flags
= IRQF_DISABLED
| IRQF_TIMER
| IRQF_IRQPOLL
,
119 .mask
= CPU_MASK_NONE
,
122 static void cmt_clk_init(struct clk
*clk
)
124 u8 divisor
= CMT_CMCSR_INIT
& 0x3;
125 ctrl_inw(CMT_CMCSR_0
);
126 ctrl_outw(CMT_CMCSR_INIT
, CMT_CMCSR_0
);
127 clk
->parent
= clk_get(NULL
, "module_clk");
128 clk
->rate
= clk
->parent
->rate
/ (8 << (divisor
<< 1));
131 static void cmt_clk_recalc(struct clk
*clk
)
133 u8 divisor
= ctrl_inw(CMT_CMCSR_0
) & 0x3;
134 clk
->rate
= clk
->parent
->rate
/ (8 << (divisor
<< 1));
137 static struct clk_ops cmt_clk_ops
= {
138 .init
= cmt_clk_init
,
139 .recalc
= cmt_clk_recalc
,
142 static struct clk cmt0_clk
= {
147 static int cmt_timer_start(void)
149 ctrl_outw(ctrl_inw(CMT_CMSTR
) | 0x01, CMT_CMSTR
);
153 static int cmt_timer_stop(void)
155 ctrl_outw(ctrl_inw(CMT_CMSTR
) & ~0x01, CMT_CMSTR
);
159 static int cmt_timer_init(void)
161 unsigned long interval
;
165 setup_irq(CONFIG_SH_TIMER_IRQ
, &cmt_irq
);
167 cmt0_clk
.parent
= clk_get(NULL
, "module_clk");
171 interval
= cmt0_clk
.parent
->rate
/ 8 / HZ
;
172 printk(KERN_INFO
"Interval = %ld\n", interval
);
174 ctrl_outw(interval
, CMT_CMCOR_0
);
176 clk_register(&cmt0_clk
);
177 clk_enable(&cmt0_clk
);
184 struct sys_timer_ops cmt_timer_ops
= {
185 .init
= cmt_timer_init
,
186 .start
= cmt_timer_start
,
187 .stop
= cmt_timer_stop
,
188 #ifndef CONFIG_GENERIC_TIME
189 .get_offset
= cmt_timer_get_offset
,
193 struct sys_timer cmt_timer
= {
195 .ops
= &cmt_timer_ops
,