| 1 | /* |
| 2 | * Cpufreq driver for the loongson-2 processors |
| 3 | * |
| 4 | * The 2E revision of loongson processor not support this feature. |
| 5 | * |
| 6 | * Copyright (C) 2006 - 2008 Lemote Inc. & Institute of Computing Technology |
| 7 | * Author: Yanhua, yanh@lemote.com |
| 8 | * |
| 9 | * This file is subject to the terms and conditions of the GNU General Public |
| 10 | * License. See the file "COPYING" in the main directory of this archive |
| 11 | * for more details. |
| 12 | */ |
| 13 | |
| 14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| 15 | |
| 16 | #include <linux/cpufreq.h> |
| 17 | #include <linux/module.h> |
| 18 | #include <linux/err.h> |
| 19 | #include <linux/delay.h> |
| 20 | #include <linux/platform_device.h> |
| 21 | |
| 22 | #include <asm/idle.h> |
| 23 | |
| 24 | #include <asm/mach-loongson2ef/loongson.h> |
| 25 | |
| 26 | static uint nowait; |
| 27 | |
| 28 | static void (*saved_cpu_wait) (void); |
| 29 | |
| 30 | static int loongson2_cpu_freq_notifier(struct notifier_block *nb, |
| 31 | unsigned long val, void *data); |
| 32 | |
| 33 | static struct notifier_block loongson2_cpufreq_notifier_block = { |
| 34 | .notifier_call = loongson2_cpu_freq_notifier |
| 35 | }; |
| 36 | |
| 37 | static int loongson2_cpu_freq_notifier(struct notifier_block *nb, |
| 38 | unsigned long val, void *data) |
| 39 | { |
| 40 | if (val == CPUFREQ_POSTCHANGE) |
| 41 | current_cpu_data.udelay_val = loops_per_jiffy; |
| 42 | |
| 43 | return 0; |
| 44 | } |
| 45 | |
| 46 | /* |
| 47 | * Here we notify other drivers of the proposed change and the final change. |
| 48 | */ |
| 49 | static int loongson2_cpufreq_target(struct cpufreq_policy *policy, |
| 50 | unsigned int index) |
| 51 | { |
| 52 | unsigned int freq; |
| 53 | |
| 54 | freq = |
| 55 | ((cpu_clock_freq / 1000) * |
| 56 | loongson2_clockmod_table[index].driver_data) / 8; |
| 57 | |
| 58 | /* setting the cpu frequency */ |
| 59 | loongson2_cpu_set_rate(freq); |
| 60 | |
| 61 | return 0; |
| 62 | } |
| 63 | |
| 64 | static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy) |
| 65 | { |
| 66 | int i; |
| 67 | unsigned long rate; |
| 68 | int ret; |
| 69 | |
| 70 | rate = cpu_clock_freq / 1000; |
| 71 | if (!rate) |
| 72 | return -EINVAL; |
| 73 | |
| 74 | /* clock table init */ |
| 75 | for (i = 2; |
| 76 | (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END); |
| 77 | i++) |
| 78 | loongson2_clockmod_table[i].frequency = (rate * i) / 8; |
| 79 | |
| 80 | ret = loongson2_cpu_set_rate(rate); |
| 81 | if (ret) |
| 82 | return ret; |
| 83 | |
| 84 | cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0); |
| 85 | return 0; |
| 86 | } |
| 87 | |
| 88 | static struct cpufreq_driver loongson2_cpufreq_driver = { |
| 89 | .name = "loongson2", |
| 90 | .init = loongson2_cpufreq_cpu_init, |
| 91 | .verify = cpufreq_generic_frequency_table_verify, |
| 92 | .target_index = loongson2_cpufreq_target, |
| 93 | .get = cpufreq_generic_get, |
| 94 | .attr = cpufreq_generic_attr, |
| 95 | }; |
| 96 | |
| 97 | static const struct platform_device_id platform_device_ids[] = { |
| 98 | { |
| 99 | .name = "loongson2_cpufreq", |
| 100 | }, |
| 101 | {} |
| 102 | }; |
| 103 | |
| 104 | MODULE_DEVICE_TABLE(platform, platform_device_ids); |
| 105 | |
| 106 | static struct platform_driver platform_driver = { |
| 107 | .driver = { |
| 108 | .name = "loongson2_cpufreq", |
| 109 | }, |
| 110 | .id_table = platform_device_ids, |
| 111 | }; |
| 112 | |
| 113 | /* |
| 114 | * This is the simple version of Loongson-2 wait, Maybe we need do this in |
| 115 | * interrupt disabled context. |
| 116 | */ |
| 117 | |
| 118 | static DEFINE_SPINLOCK(loongson2_wait_lock); |
| 119 | |
| 120 | static void loongson2_cpu_wait(void) |
| 121 | { |
| 122 | unsigned long flags; |
| 123 | u32 cpu_freq; |
| 124 | |
| 125 | spin_lock_irqsave(&loongson2_wait_lock, flags); |
| 126 | cpu_freq = readl(LOONGSON_CHIPCFG); |
| 127 | /* Put CPU into wait mode */ |
| 128 | writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG); |
| 129 | /* Restore CPU state */ |
| 130 | writel(cpu_freq, LOONGSON_CHIPCFG); |
| 131 | spin_unlock_irqrestore(&loongson2_wait_lock, flags); |
| 132 | local_irq_enable(); |
| 133 | } |
| 134 | |
| 135 | static int __init cpufreq_init(void) |
| 136 | { |
| 137 | int ret; |
| 138 | |
| 139 | /* Register platform stuff */ |
| 140 | ret = platform_driver_register(&platform_driver); |
| 141 | if (ret) |
| 142 | return ret; |
| 143 | |
| 144 | pr_info("Loongson-2F CPU frequency driver\n"); |
| 145 | |
| 146 | cpufreq_register_notifier(&loongson2_cpufreq_notifier_block, |
| 147 | CPUFREQ_TRANSITION_NOTIFIER); |
| 148 | |
| 149 | ret = cpufreq_register_driver(&loongson2_cpufreq_driver); |
| 150 | |
| 151 | if (!ret && !nowait) { |
| 152 | saved_cpu_wait = cpu_wait; |
| 153 | cpu_wait = loongson2_cpu_wait; |
| 154 | } |
| 155 | |
| 156 | return ret; |
| 157 | } |
| 158 | |
| 159 | static void __exit cpufreq_exit(void) |
| 160 | { |
| 161 | if (!nowait && saved_cpu_wait) |
| 162 | cpu_wait = saved_cpu_wait; |
| 163 | cpufreq_unregister_driver(&loongson2_cpufreq_driver); |
| 164 | cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block, |
| 165 | CPUFREQ_TRANSITION_NOTIFIER); |
| 166 | |
| 167 | platform_driver_unregister(&platform_driver); |
| 168 | } |
| 169 | |
| 170 | module_init(cpufreq_init); |
| 171 | module_exit(cpufreq_exit); |
| 172 | |
| 173 | module_param(nowait, uint, 0644); |
| 174 | MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait"); |
| 175 | |
| 176 | MODULE_AUTHOR("Yanhua <yanh@lemote.com>"); |
| 177 | MODULE_DESCRIPTION("cpufreq driver for Loongson2F"); |
| 178 | MODULE_LICENSE("GPL"); |