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-loongson64/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 cpu = policy->cpu; 55 cpumask_t cpus_allowed; 56 unsigned int freq; 57 58 cpus_allowed = current->cpus_allowed; 59 set_cpus_allowed_ptr(current, cpumask_of(cpu)); 60 61 freq = 62 ((cpu_clock_freq / 1000) * 63 loongson2_clockmod_table[index].driver_data) / 8; 64 65 set_cpus_allowed_ptr(current, &cpus_allowed); 66 67 /* setting the cpu frequency */ 68 clk_set_rate(policy->clk, freq * 1000); 69 70 return 0; 71 } 72 73 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy) 74 { 75 struct clk *cpuclk; 76 int i; 77 unsigned long rate; 78 int ret; 79 80 cpuclk = clk_get(NULL, "cpu_clk"); 81 if (IS_ERR(cpuclk)) { 82 pr_err("couldn't get CPU clk\n"); 83 return PTR_ERR(cpuclk); 84 } 85 86 rate = cpu_clock_freq / 1000; 87 if (!rate) { 88 clk_put(cpuclk); 89 return -EINVAL; 90 } 91 92 /* clock table init */ 93 for (i = 2; 94 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END); 95 i++) 96 loongson2_clockmod_table[i].frequency = (rate * i) / 8; 97 98 ret = clk_set_rate(cpuclk, rate * 1000); 99 if (ret) { 100 clk_put(cpuclk); 101 return ret; 102 } 103 104 policy->clk = cpuclk; 105 return cpufreq_generic_init(policy, &loongson2_clockmod_table[0], 0); 106 } 107 108 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy) 109 { 110 clk_put(policy->clk); 111 return 0; 112 } 113 114 static struct cpufreq_driver loongson2_cpufreq_driver = { 115 .name = "loongson2", 116 .init = loongson2_cpufreq_cpu_init, 117 .verify = cpufreq_generic_frequency_table_verify, 118 .target_index = loongson2_cpufreq_target, 119 .get = cpufreq_generic_get, 120 .exit = loongson2_cpufreq_exit, 121 .attr = cpufreq_generic_attr, 122 }; 123 124 static struct platform_device_id platform_device_ids[] = { 125 { 126 .name = "loongson2_cpufreq", 127 }, 128 {} 129 }; 130 131 MODULE_DEVICE_TABLE(platform, platform_device_ids); 132 133 static struct platform_driver platform_driver = { 134 .driver = { 135 .name = "loongson2_cpufreq", 136 }, 137 .id_table = platform_device_ids, 138 }; 139 140 /* 141 * This is the simple version of Loongson-2 wait, Maybe we need do this in 142 * interrupt disabled context. 143 */ 144 145 static DEFINE_SPINLOCK(loongson2_wait_lock); 146 147 static void loongson2_cpu_wait(void) 148 { 149 unsigned long flags; 150 u32 cpu_freq; 151 152 spin_lock_irqsave(&loongson2_wait_lock, flags); 153 cpu_freq = LOONGSON_CHIPCFG(0); 154 LOONGSON_CHIPCFG(0) &= ~0x7; /* Put CPU into wait mode */ 155 LOONGSON_CHIPCFG(0) = cpu_freq; /* Restore CPU state */ 156 spin_unlock_irqrestore(&loongson2_wait_lock, flags); 157 local_irq_enable(); 158 } 159 160 static int __init cpufreq_init(void) 161 { 162 int ret; 163 164 /* Register platform stuff */ 165 ret = platform_driver_register(&platform_driver); 166 if (ret) 167 return ret; 168 169 pr_info("Loongson-2F CPU frequency driver\n"); 170 171 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block, 172 CPUFREQ_TRANSITION_NOTIFIER); 173 174 ret = cpufreq_register_driver(&loongson2_cpufreq_driver); 175 176 if (!ret && !nowait) { 177 saved_cpu_wait = cpu_wait; 178 cpu_wait = loongson2_cpu_wait; 179 } 180 181 return ret; 182 } 183 184 static void __exit cpufreq_exit(void) 185 { 186 if (!nowait && saved_cpu_wait) 187 cpu_wait = saved_cpu_wait; 188 cpufreq_unregister_driver(&loongson2_cpufreq_driver); 189 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block, 190 CPUFREQ_TRANSITION_NOTIFIER); 191 192 platform_driver_unregister(&platform_driver); 193 } 194 195 module_init(cpufreq_init); 196 module_exit(cpufreq_exit); 197 198 module_param(nowait, uint, 0644); 199 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait"); 200 201 MODULE_AUTHOR("Yanhua <yanh@lemote.com>"); 202 MODULE_DESCRIPTION("cpufreq driver for Loongson2F"); 203 MODULE_LICENSE("GPL"); 204