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c53c9cf6 AV |
1 | /* |
2 | * arch/arm/mach-ks8695/time.c | |
3 | * | |
4 | * Copyright (C) 2006 Ben Dooks <ben@simtec.co.uk> | |
5 | * Copyright (C) 2006 Simtec Electronics | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or modify | |
8 | * it under the terms of the GNU General Public License as published by | |
9 | * the Free Software Foundation; either version 2 of the License, or | |
10 | * (at your option) any later version. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, | |
13 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
15 | * GNU General Public License for more details. | |
16 | * | |
17 | * You should have received a copy of the GNU General Public License | |
18 | * along with this program; if not, write to the Free Software | |
19 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA | |
20 | */ | |
21 | ||
22 | #include <linux/init.h> | |
23 | #include <linux/interrupt.h> | |
24 | #include <linux/irq.h> | |
25 | #include <linux/kernel.h> | |
26 | #include <linux/sched.h> | |
27 | ||
28 | #include <asm/io.h> | |
29 | #include <asm/mach/time.h> | |
30 | ||
a09e64fb RK |
31 | #include <mach/regs-timer.h> |
32 | #include <mach/regs-irq.h> | |
c53c9cf6 AV |
33 | |
34 | #include "generic.h" | |
35 | ||
36 | /* | |
37 | * Returns number of ms since last clock interrupt. Note that interrupts | |
38 | * will have been disabled by do_gettimeoffset() | |
39 | */ | |
40 | static unsigned long ks8695_gettimeoffset (void) | |
41 | { | |
42 | unsigned long elapsed, tick2, intpending; | |
43 | ||
44 | /* | |
45 | * Get the current number of ticks. Note that there is a race | |
46 | * condition between us reading the timer and checking for an | |
47 | * interrupt. We solve this by ensuring that the counter has not | |
48 | * reloaded between our two reads. | |
49 | */ | |
50 | elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD); | |
51 | do { | |
52 | tick2 = elapsed; | |
53 | intpending = __raw_readl(KS8695_IRQ_VA + KS8695_INTST) & (1 << KS8695_IRQ_TIMER1); | |
54 | elapsed = __raw_readl(KS8695_TMR_VA + KS8695_T1TC) + __raw_readl(KS8695_TMR_VA + KS8695_T1PD); | |
55 | } while (elapsed > tick2); | |
56 | ||
57 | /* Convert to number of ticks expired (not remaining) */ | |
58 | elapsed = (CLOCK_TICK_RATE / HZ) - elapsed; | |
59 | ||
60 | /* Is interrupt pending? If so, then timer has been reloaded already. */ | |
61 | if (intpending) | |
62 | elapsed += (CLOCK_TICK_RATE / HZ); | |
63 | ||
64 | /* Convert ticks to usecs */ | |
65 | return (unsigned long)(elapsed * (tick_nsec / 1000)) / LATCH; | |
66 | } | |
67 | ||
68 | /* | |
69 | * IRQ handler for the timer. | |
70 | */ | |
71 | static irqreturn_t ks8695_timer_interrupt(int irq, void *dev_id) | |
72 | { | |
c53c9cf6 | 73 | timer_tick(); |
c53c9cf6 AV |
74 | return IRQ_HANDLED; |
75 | } | |
76 | ||
77 | static struct irqaction ks8695_timer_irq = { | |
78 | .name = "ks8695_tick", | |
79 | .flags = IRQF_DISABLED | IRQF_TIMER, | |
80 | .handler = ks8695_timer_interrupt, | |
81 | }; | |
82 | ||
83 | static void ks8695_timer_setup(void) | |
84 | { | |
85 | unsigned long tmout = CLOCK_TICK_RATE / HZ; | |
86 | unsigned long tmcon; | |
87 | ||
88 | /* disable timer1 */ | |
89 | tmcon = __raw_readl(KS8695_TMR_VA + KS8695_TMCON); | |
90 | __raw_writel(tmcon & ~TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON); | |
91 | ||
92 | __raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1TC); | |
93 | __raw_writel(tmout / 2, KS8695_TMR_VA + KS8695_T1PD); | |
94 | ||
95 | /* re-enable timer1 */ | |
96 | __raw_writel(tmcon | TMCON_T1EN, KS8695_TMR_VA + KS8695_TMCON); | |
97 | } | |
98 | ||
99 | static void __init ks8695_timer_init (void) | |
100 | { | |
101 | ks8695_timer_setup(); | |
102 | ||
103 | /* Enable timer interrupts */ | |
104 | setup_irq(KS8695_IRQ_TIMER1, &ks8695_timer_irq); | |
105 | } | |
106 | ||
107 | struct sys_timer ks8695_timer = { | |
108 | .init = ks8695_timer_init, | |
109 | .offset = ks8695_gettimeoffset, | |
110 | .resume = ks8695_timer_setup, | |
111 | }; |