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. & Insititute 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 #include <linux/cpufreq.h> 14 #include <linux/module.h> 15 #include <linux/err.h> 16 #include <linux/sched.h> /* set_cpus_allowed() */ 17 #include <linux/delay.h> 18 #include <linux/platform_device.h> 19 20 #include <asm/clock.h> 21 22 #include <asm/mach-loongson/loongson.h> 23 24 static uint nowait; 25 26 static struct clk *cpuclk; 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 static unsigned int loongson2_cpufreq_get(unsigned int cpu) 47 { 48 return clk_get_rate(cpuclk); 49 } 50 51 /* 52 * Here we notify other drivers of the proposed change and the final change. 53 */ 54 static int loongson2_cpufreq_target(struct cpufreq_policy *policy, 55 unsigned int target_freq, 56 unsigned int relation) 57 { 58 unsigned int cpu = policy->cpu; 59 unsigned int newstate = 0; 60 cpumask_t cpus_allowed; 61 struct cpufreq_freqs freqs; 62 unsigned int freq; 63 64 cpus_allowed = current->cpus_allowed; 65 set_cpus_allowed_ptr(current, cpumask_of(cpu)); 66 67 if (cpufreq_frequency_table_target 68 (policy, &loongson2_clockmod_table[0], target_freq, relation, 69 &newstate)) 70 return -EINVAL; 71 72 freq = 73 ((cpu_clock_freq / 1000) * 74 loongson2_clockmod_table[newstate].index) / 8; 75 if (freq < policy->min || freq > policy->max) 76 return -EINVAL; 77 78 pr_debug("cpufreq: requested frequency %u Hz\n", target_freq * 1000); 79 80 freqs.old = loongson2_cpufreq_get(cpu); 81 freqs.new = freq; 82 freqs.flags = 0; 83 84 if (freqs.new == freqs.old) 85 return 0; 86 87 /* notifiers */ 88 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); 89 90 set_cpus_allowed_ptr(current, &cpus_allowed); 91 92 /* setting the cpu frequency */ 93 clk_set_rate(cpuclk, freq); 94 95 /* notifiers */ 96 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); 97 98 pr_debug("cpufreq: set frequency %u kHz\n", freq); 99 100 return 0; 101 } 102 103 static int loongson2_cpufreq_cpu_init(struct cpufreq_policy *policy) 104 { 105 int i; 106 unsigned long rate; 107 int ret; 108 109 cpuclk = clk_get(NULL, "cpu_clk"); 110 if (IS_ERR(cpuclk)) { 111 printk(KERN_ERR "cpufreq: couldn't get CPU clk\n"); 112 return PTR_ERR(cpuclk); 113 } 114 115 rate = cpu_clock_freq / 1000; 116 if (!rate) { 117 clk_put(cpuclk); 118 return -EINVAL; 119 } 120 ret = clk_set_rate(cpuclk, rate); 121 if (ret) { 122 clk_put(cpuclk); 123 return ret; 124 } 125 126 /* clock table init */ 127 for (i = 2; 128 (loongson2_clockmod_table[i].frequency != CPUFREQ_TABLE_END); 129 i++) 130 loongson2_clockmod_table[i].frequency = (rate * i) / 8; 131 132 policy->cur = loongson2_cpufreq_get(policy->cpu); 133 134 cpufreq_frequency_table_get_attr(&loongson2_clockmod_table[0], 135 policy->cpu); 136 137 return cpufreq_frequency_table_cpuinfo(policy, 138 &loongson2_clockmod_table[0]); 139 } 140 141 static int loongson2_cpufreq_verify(struct cpufreq_policy *policy) 142 { 143 return cpufreq_frequency_table_verify(policy, 144 &loongson2_clockmod_table[0]); 145 } 146 147 static int loongson2_cpufreq_exit(struct cpufreq_policy *policy) 148 { 149 clk_put(cpuclk); 150 return 0; 151 } 152 153 static struct freq_attr *loongson2_table_attr[] = { 154 &cpufreq_freq_attr_scaling_available_freqs, 155 NULL, 156 }; 157 158 static struct cpufreq_driver loongson2_cpufreq_driver = { 159 .owner = THIS_MODULE, 160 .name = "loongson2", 161 .init = loongson2_cpufreq_cpu_init, 162 .verify = loongson2_cpufreq_verify, 163 .target = loongson2_cpufreq_target, 164 .get = loongson2_cpufreq_get, 165 .exit = loongson2_cpufreq_exit, 166 .attr = loongson2_table_attr, 167 }; 168 169 static struct platform_device_id platform_device_ids[] = { 170 { 171 .name = "loongson2_cpufreq", 172 }, 173 {} 174 }; 175 176 MODULE_DEVICE_TABLE(platform, platform_device_ids); 177 178 static struct platform_driver platform_driver = { 179 .driver = { 180 .name = "loongson2_cpufreq", 181 .owner = THIS_MODULE, 182 }, 183 .id_table = platform_device_ids, 184 }; 185 186 /* 187 * This is the simple version of Loongson-2 wait, Maybe we need do this in 188 * interrupt disabled context. 189 */ 190 191 static DEFINE_SPINLOCK(loongson2_wait_lock); 192 193 static void loongson2_cpu_wait(void) 194 { 195 unsigned long flags; 196 u32 cpu_freq; 197 198 spin_lock_irqsave(&loongson2_wait_lock, flags); 199 cpu_freq = LOONGSON_CHIPCFG0; 200 LOONGSON_CHIPCFG0 &= ~0x7; /* Put CPU into wait mode */ 201 LOONGSON_CHIPCFG0 = cpu_freq; /* Restore CPU state */ 202 spin_unlock_irqrestore(&loongson2_wait_lock, flags); 203 } 204 205 static int __init cpufreq_init(void) 206 { 207 int ret; 208 209 /* Register platform stuff */ 210 ret = platform_driver_register(&platform_driver); 211 if (ret) 212 return ret; 213 214 pr_info("cpufreq: Loongson-2F CPU frequency driver.\n"); 215 216 cpufreq_register_notifier(&loongson2_cpufreq_notifier_block, 217 CPUFREQ_TRANSITION_NOTIFIER); 218 219 ret = cpufreq_register_driver(&loongson2_cpufreq_driver); 220 221 if (!ret && !nowait) { 222 saved_cpu_wait = cpu_wait; 223 cpu_wait = loongson2_cpu_wait; 224 } 225 226 return ret; 227 } 228 229 static void __exit cpufreq_exit(void) 230 { 231 if (!nowait && saved_cpu_wait) 232 cpu_wait = saved_cpu_wait; 233 cpufreq_unregister_driver(&loongson2_cpufreq_driver); 234 cpufreq_unregister_notifier(&loongson2_cpufreq_notifier_block, 235 CPUFREQ_TRANSITION_NOTIFIER); 236 237 platform_driver_unregister(&platform_driver); 238 } 239 240 module_init(cpufreq_init); 241 module_exit(cpufreq_exit); 242 243 module_param(nowait, uint, 0644); 244 MODULE_PARM_DESC(nowait, "Disable Loongson-2F specific wait"); 245 246 MODULE_AUTHOR("Yanhua <yanh@lemote.com>"); 247 MODULE_DESCRIPTION("cpufreq driver for Loongson2F"); 248 MODULE_LICENSE("GPL"); 249