diff options
author | Russell King <rmk@dyn-67.arm.linux.org.uk> | 2005-11-09 05:50:29 -0500 |
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committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2005-11-09 05:50:29 -0500 |
commit | 2a98beb6390aef8fad85103ea25b3b1ace8015b5 (patch) | |
tree | 09f3e0de9a49f0f61d7f44c6c03218bf29f5d1dd /arch/arm/mach-realview/localtimer.c | |
parent | 37ee16ae93a3e4ae7dd51beb81d249f5f12a55c2 (diff) |
[ARM SMP] Add local timer support for Realview MPcore
Add platform specific parts for local timer support for the
Realview board.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Diffstat (limited to 'arch/arm/mach-realview/localtimer.c')
-rw-r--r-- | arch/arm/mach-realview/localtimer.c | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/arch/arm/mach-realview/localtimer.c b/arch/arm/mach-realview/localtimer.c new file mode 100644 index 000000000000..5e917e37d095 --- /dev/null +++ b/arch/arm/mach-realview/localtimer.c | |||
@@ -0,0 +1,130 @@ | |||
1 | /* | ||
2 | * linux/arch/arm/mach-realview/localtimer.c | ||
3 | * | ||
4 | * Copyright (C) 2002 ARM Ltd. | ||
5 | * All Rights Reserved | ||
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 version 2 as | ||
9 | * published by the Free Software Foundation. | ||
10 | */ | ||
11 | #include <linux/init.h> | ||
12 | #include <linux/kernel.h> | ||
13 | #include <linux/delay.h> | ||
14 | #include <linux/device.h> | ||
15 | #include <linux/smp.h> | ||
16 | |||
17 | #include <asm/mach/time.h> | ||
18 | #include <asm/hardware/arm_twd.h> | ||
19 | #include <asm/hardware/gic.h> | ||
20 | #include <asm/hardware.h> | ||
21 | #include <asm/io.h> | ||
22 | #include <asm/irq.h> | ||
23 | |||
24 | #include "core.h" | ||
25 | |||
26 | #define TWD_BASE(cpu) (__io_address(REALVIEW_TWD_BASE) + \ | ||
27 | ((cpu) * REALVIEW_TWD_SIZE)) | ||
28 | |||
29 | static unsigned long mpcore_timer_rate; | ||
30 | |||
31 | /* | ||
32 | * local_timer_ack: checks for a local timer interrupt. | ||
33 | * | ||
34 | * If a local timer interrupt has occured, acknowledge and return 1. | ||
35 | * Otherwise, return 0. | ||
36 | */ | ||
37 | int local_timer_ack(void) | ||
38 | { | ||
39 | void __iomem *base = TWD_BASE(smp_processor_id()); | ||
40 | |||
41 | if (__raw_readl(base + TWD_TIMER_INTSTAT)) { | ||
42 | __raw_writel(1, base + TWD_TIMER_INTSTAT); | ||
43 | return 1; | ||
44 | } | ||
45 | |||
46 | return 0; | ||
47 | } | ||
48 | |||
49 | void __cpuinit local_timer_setup(unsigned int cpu) | ||
50 | { | ||
51 | void __iomem *base = TWD_BASE(cpu); | ||
52 | unsigned int load, offset; | ||
53 | u64 waitjiffies; | ||
54 | unsigned int count; | ||
55 | |||
56 | /* | ||
57 | * If this is the first time round, we need to work out how fast | ||
58 | * the timer ticks | ||
59 | */ | ||
60 | if (mpcore_timer_rate == 0) { | ||
61 | printk("Calibrating local timer... "); | ||
62 | |||
63 | /* Wait for a tick to start */ | ||
64 | waitjiffies = get_jiffies_64() + 1; | ||
65 | |||
66 | while (get_jiffies_64() < waitjiffies) | ||
67 | udelay(10); | ||
68 | |||
69 | /* OK, now the tick has started, let's get the timer going */ | ||
70 | waitjiffies += 5; | ||
71 | |||
72 | /* enable, no interrupt or reload */ | ||
73 | __raw_writel(0x1, base + TWD_TIMER_CONTROL); | ||
74 | |||
75 | /* maximum value */ | ||
76 | __raw_writel(0xFFFFFFFFU, base + TWD_TIMER_COUNTER); | ||
77 | |||
78 | while (get_jiffies_64() < waitjiffies) | ||
79 | udelay(10); | ||
80 | |||
81 | count = __raw_readl(base + TWD_TIMER_COUNTER); | ||
82 | |||
83 | mpcore_timer_rate = (0xFFFFFFFFU - count) * (HZ / 5); | ||
84 | |||
85 | printk("%lu.%02luMHz.\n", mpcore_timer_rate / 1000000, | ||
86 | (mpcore_timer_rate / 100000) % 100); | ||
87 | } | ||
88 | |||
89 | load = mpcore_timer_rate / HZ; | ||
90 | |||
91 | __raw_writel(load, base + TWD_TIMER_LOAD); | ||
92 | __raw_writel(0x7, base + TWD_TIMER_CONTROL); | ||
93 | |||
94 | /* | ||
95 | * Now maneuver our local tick into the right part of the jiffy. | ||
96 | * Start by working out where within the tick our local timer | ||
97 | * interrupt should go. | ||
98 | */ | ||
99 | offset = ((mpcore_timer_rate / HZ) / (NR_CPUS + 1)) * (cpu + 1); | ||
100 | |||
101 | /* | ||
102 | * gettimeoffset() will return a number of us since the last tick. | ||
103 | * Convert this number of us to a local timer tick count. | ||
104 | * Be careful of integer overflow whilst keeping maximum precision. | ||
105 | * | ||
106 | * with HZ=100 and 1MHz (fpga) ~ 1GHz processor: | ||
107 | * load = 1 ~ 10,000 | ||
108 | * mpcore_timer_rate/10000 = 100 ~ 100,000 | ||
109 | * | ||
110 | * so the multiply value will be less than 10^9 always. | ||
111 | */ | ||
112 | load = (system_timer->offset() * (mpcore_timer_rate / 10000)) / 100; | ||
113 | |||
114 | /* Add on our offset to get the load value */ | ||
115 | load = (load + offset) % (mpcore_timer_rate / HZ); | ||
116 | |||
117 | __raw_writel(load, base + TWD_TIMER_COUNTER); | ||
118 | |||
119 | /* Make sure our local interrupt controller has this enabled */ | ||
120 | __raw_writel(1 << IRQ_LOCALTIMER, | ||
121 | __io_address(REALVIEW_GIC_DIST_BASE) + GIC_DIST_ENABLE_SET); | ||
122 | } | ||
123 | |||
124 | /* | ||
125 | * take a local timer down | ||
126 | */ | ||
127 | void __cpuexit local_timer_stop(unsigned int cpu) | ||
128 | { | ||
129 | __raw_writel(0, TWD_BASE(cpu) + TWD_TIMER_CONTROL); | ||
130 | } | ||