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/sched.h> /* set_cpus_allowed() */ 20 #include <linux/delay.h> 21 #include <linux/platform_device.h> 22 23 #include <asm/clock.h> 24 #include <asm/idle.h> 25 26 #include <asm/mach-loongson2ef/loongson.h> 27 28 static uint nowait; 29 30 static void (*saved_cpu_wait) (void); 31 32 static int loongson2_cpu_freq_notifier(struct notifier_block *nb, 33 unsigned long val, void *data); 34 35 static struct notifier_block loongson2_cpufreq_notifier_block = { 36 .notifier_call = loongson2_cpu_freq_notifier 37 }; 38 39 static int loongson2_cpu_freq_notifier(struct notifier_block *nb, 40 unsigned long val, void *data) 41 { 42 if (val == CPUFREQ_POSTCHANGE) 43 current_cpu_data.udelay_val = loops_per_jiffy; 44 45 return 0; 46 } 47 48 /* 49 * Here we notify other drivers of the proposed change and the final change. 50 */ 51 static int loongson2_cpufreq_target(struct cpufreq_policy *policy, 52 unsigned int index) 53 { 54 unsigned int freq; 55 56 freq = 57 ((cpu_clock_freq / 1000) * 58 loongson2_clockmod_table[index].driver_data) / 8; 59 60 /* setting the cpu frequency */ 61 clk_set_rate(policy->clk, freq * 1000); 62 63 return 0; 64 } 65 66 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy) 67 { 68 struct clk *cpuclk; 69 int i; 70 unsigned long rate; 71 int ret; 72 73 cpuclk = clk_get(NULL, "cpu_clk"); 74 if (IS_ERR(cpuclk)) { 75 pr_err("couldn't get CPU clk\n"); 76 return PTR_ERR(cpuclk); 77 } 78 79 rate = cpu_clock_freq / 1000; 80 if (!rate) { 81 clk_put(cpuclk); 82 return -EINVAL; 83 } 84 85 /* clock table init */ 86 for (i = 2; 87 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END); 88 i++) 89 loongson2_clockmod_table[i].frequency = (rate * i) / 8; 90 91 ret = clk_set_rate(cpuclk, rate * 1000); 92 if (ret) { 93 clk_put(cpuclk); 94 return ret; 95 } 96 97 policy->clk = cpuclk; 98 cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0); 99 return 0; 100 } 101 102 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy) 103 { 104 clk_put(policy->clk); 105 return 0; 106 } 107 108 static struct cpufreq_driver loongson2_cpufreq_driver = { 109 .name = "loongson2", 110 .init = loongson2_cpufreq_cpu_init, 111 .verify = cpufreq_generic_frequency_table_verify, 112 .target_index = loongson2_cpufreq_target, 113 .get = cpufreq_generic_get, 114 .exit = loongson2_cpufreq_exit, 115 .attr = cpufreq_generic_attr, 116 }; 117 118 static const struct platform_device_id platform_device_ids[] = { 119 { 120 .name = "loongson2_cpufreq", 121 }, 122 {} 123 }; 124 125 MODULE_DEVICE_TABLE(platform, platform_device_ids); 126 127 static struct platform_driver platform_driver = { 128 .driver = { 129 .name = "loongson2_cpufreq", 130 }, 131 .id_table = platform_device_ids, 132 }; 133 134 /* 135 * This is the simple version of Loongson-2 wait, Maybe we need do this in 136 * interrupt disabled context. 137 */ 138 139 static DEFINE_SPINLOCK(loongson2_wait_lock); 140 141 static void loongson2_cpu_wait(void) 142 { 143 unsigned long flags; 144 u32 cpu_freq; 145 146 spin_lock_irqsave(&loongson2_wait_lock, flags); 147 cpu_freq = readl(LOONGSON_CHIPCFG); 148 /* Put CPU into wait mode */ 149 writel(readl(LOONGSON_CHIPCFG) & ~0x7, LOONGSON_CHIPCFG); 150 /* Restore CPU state */ 151 writel(cpu_freq, LOONGSON_CHIPCFG); 152 spin_unlock_irqrestore(&loongson2_wait_lock, flags); 153 local_irq_enable(); 154 } 155 156 static int __init cpufreq_init(void) 157 { 158 int ret; 159 160 /* Register platform stuff */ 161 ret = platform_driver_register(&platform_driver); 162 if (ret) 163 return ret; 164 165 pr_info("Loongson-2F CPU frequency driver\n"); 166 167 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block, 168 CPUFREQ_TRANSITION_NOTIFIER); 169 170 ret = cpufreq_register_driver(&loongson2_cpufreq_driver); 171 172 if (!ret && !nowait) { 173 saved_cpu_wait = cpu_wait; 174 cpu_wait = loongson2_cpu_wait; 175 } 176 177 return ret; 178 } 179 180 static void __exit cpufreq_exit(void) 181 { 182 if (!nowait && saved_cpu_wait) 183 cpu_wait = saved_cpu_wait; 184 cpufreq_unregister_driver(&loongson2_cpufreq_driver); 185 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block, 186 CPUFREQ_TRANSITION_NOTIFIER); 187 188 platform_driver_unregister(&platform_driver); 189 } 190 191 module_init(cpufreq_init); 192 module_exit(cpufreq_exit); 193 194 module_param(nowait, uint, 0644); 195 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait"); 196 197 MODULE_AUTHOR("Yanhua <yanh@lemote.com>"); 198 MODULE_DESCRIPTION("cpufreq driver for Loongson2F"); 199 MODULE_LICENSE("GPL"); 200