1 /* 2 * CPU frequency scaling for OMAP using OPP information 3 * 4 * Copyright (C) 2005 Nokia Corporation 5 * Written by Tony Lindgren <tony@atomide.com> 6 * 7 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King 8 * 9 * Copyright (C) 2007-2011 Texas Instruments, Inc. 10 * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar 11 * 12 * This program is free software; you can redistribute it and/or modify 13 * it under the terms of the GNU General Public License version 2 as 14 * published by the Free Software Foundation. 15 */ 16 #include <linux/types.h> 17 #include <linux/kernel.h> 18 #include <linux/sched.h> 19 #include <linux/cpufreq.h> 20 #include <linux/delay.h> 21 #include <linux/init.h> 22 #include <linux/err.h> 23 #include <linux/clk.h> 24 #include <linux/io.h> 25 #include <linux/opp.h> 26 #include <linux/cpu.h> 27 #include <linux/module.h> 28 #include <linux/regulator/consumer.h> 29 30 #include <asm/smp_plat.h> 31 #include <asm/cpu.h> 32 33 /* OPP tolerance in percentage */ 34 #define OPP_TOLERANCE 4 35 36 static struct cpufreq_frequency_table *freq_table; 37 static atomic_t freq_table_users = ATOMIC_INIT(0); 38 static struct clk *mpu_clk; 39 static struct device *mpu_dev; 40 static struct regulator *mpu_reg; 41 42 static int omap_verify_speed(struct cpufreq_policy *policy) 43 { 44 if (!freq_table) 45 return -EINVAL; 46 return cpufreq_frequency_table_verify(policy, freq_table); 47 } 48 49 static unsigned int omap_getspeed(unsigned int cpu) 50 { 51 unsigned long rate; 52 53 if (cpu >= NR_CPUS) 54 return 0; 55 56 rate = clk_get_rate(mpu_clk) / 1000; 57 return rate; 58 } 59 60 static int omap_target(struct cpufreq_policy *policy, 61 unsigned int target_freq, 62 unsigned int relation) 63 { 64 unsigned int i; 65 int r, ret = 0; 66 struct cpufreq_freqs freqs; 67 struct opp *opp; 68 unsigned long freq, volt = 0, volt_old = 0, tol = 0; 69 70 if (!freq_table) { 71 dev_err(mpu_dev, "%s: cpu%d: no freq table!\n", __func__, 72 policy->cpu); 73 return -EINVAL; 74 } 75 76 ret = cpufreq_frequency_table_target(policy, freq_table, target_freq, 77 relation, &i); 78 if (ret) { 79 dev_dbg(mpu_dev, "%s: cpu%d: no freq match for %d(ret=%d)\n", 80 __func__, policy->cpu, target_freq, ret); 81 return ret; 82 } 83 freqs.new = freq_table[i].frequency; 84 if (!freqs.new) { 85 dev_err(mpu_dev, "%s: cpu%d: no match for freq %d\n", __func__, 86 policy->cpu, target_freq); 87 return -EINVAL; 88 } 89 90 freqs.old = omap_getspeed(policy->cpu); 91 freqs.cpu = policy->cpu; 92 93 if (freqs.old == freqs.new && policy->cur == freqs.new) 94 return ret; 95 96 /* notifiers */ 97 for_each_cpu(i, policy->cpus) { 98 freqs.cpu = i; 99 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); 100 } 101 102 freq = freqs.new * 1000; 103 ret = clk_round_rate(mpu_clk, freq); 104 if (IS_ERR_VALUE(ret)) { 105 dev_warn(mpu_dev, 106 "CPUfreq: Cannot find matching frequency for %lu\n", 107 freq); 108 return ret; 109 } 110 freq = ret; 111 112 if (mpu_reg) { 113 opp = opp_find_freq_ceil(mpu_dev, &freq); 114 if (IS_ERR(opp)) { 115 dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n", 116 __func__, freqs.new); 117 return -EINVAL; 118 } 119 volt = opp_get_voltage(opp); 120 tol = volt * OPP_TOLERANCE / 100; 121 volt_old = regulator_get_voltage(mpu_reg); 122 } 123 124 dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n", 125 freqs.old / 1000, volt_old ? volt_old / 1000 : -1, 126 freqs.new / 1000, volt ? volt / 1000 : -1); 127 128 /* scaling up? scale voltage before frequency */ 129 if (mpu_reg && (freqs.new > freqs.old)) { 130 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol); 131 if (r < 0) { 132 dev_warn(mpu_dev, "%s: unable to scale voltage up.\n", 133 __func__); 134 freqs.new = freqs.old; 135 goto done; 136 } 137 } 138 139 ret = clk_set_rate(mpu_clk, freqs.new * 1000); 140 141 /* scaling down? scale voltage after frequency */ 142 if (mpu_reg && (freqs.new < freqs.old)) { 143 r = regulator_set_voltage(mpu_reg, volt - tol, volt + tol); 144 if (r < 0) { 145 dev_warn(mpu_dev, "%s: unable to scale voltage down.\n", 146 __func__); 147 ret = clk_set_rate(mpu_clk, freqs.old * 1000); 148 freqs.new = freqs.old; 149 goto done; 150 } 151 } 152 153 freqs.new = omap_getspeed(policy->cpu); 154 155 done: 156 /* notifiers */ 157 for_each_cpu(i, policy->cpus) { 158 freqs.cpu = i; 159 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); 160 } 161 162 return ret; 163 } 164 165 static inline void freq_table_free(void) 166 { 167 if (atomic_dec_and_test(&freq_table_users)) 168 opp_free_cpufreq_table(mpu_dev, &freq_table); 169 } 170 171 static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy) 172 { 173 int result = 0; 174 175 mpu_clk = clk_get(NULL, "cpufreq_ck"); 176 if (IS_ERR(mpu_clk)) 177 return PTR_ERR(mpu_clk); 178 179 if (policy->cpu >= NR_CPUS) { 180 result = -EINVAL; 181 goto fail_ck; 182 } 183 184 policy->cur = policy->min = policy->max = omap_getspeed(policy->cpu); 185 186 if (!freq_table) 187 result = opp_init_cpufreq_table(mpu_dev, &freq_table); 188 189 if (result) { 190 dev_err(mpu_dev, "%s: cpu%d: failed creating freq table[%d]\n", 191 __func__, policy->cpu, result); 192 goto fail_ck; 193 } 194 195 atomic_inc_return(&freq_table_users); 196 197 result = cpufreq_frequency_table_cpuinfo(policy, freq_table); 198 if (result) 199 goto fail_table; 200 201 cpufreq_frequency_table_get_attr(freq_table, policy->cpu); 202 203 policy->min = policy->cpuinfo.min_freq; 204 policy->max = policy->cpuinfo.max_freq; 205 policy->cur = omap_getspeed(policy->cpu); 206 207 /* 208 * On OMAP SMP configuartion, both processors share the voltage 209 * and clock. So both CPUs needs to be scaled together and hence 210 * needs software co-ordination. Use cpufreq affected_cpus 211 * interface to handle this scenario. Additional is_smp() check 212 * is to keep SMP_ON_UP build working. 213 */ 214 if (is_smp()) { 215 policy->shared_type = CPUFREQ_SHARED_TYPE_ANY; 216 cpumask_setall(policy->cpus); 217 } 218 219 /* FIXME: what's the actual transition time? */ 220 policy->cpuinfo.transition_latency = 300 * 1000; 221 222 return 0; 223 224 fail_table: 225 freq_table_free(); 226 fail_ck: 227 clk_put(mpu_clk); 228 return result; 229 } 230 231 static int omap_cpu_exit(struct cpufreq_policy *policy) 232 { 233 freq_table_free(); 234 clk_put(mpu_clk); 235 return 0; 236 } 237 238 static struct freq_attr *omap_cpufreq_attr[] = { 239 &cpufreq_freq_attr_scaling_available_freqs, 240 NULL, 241 }; 242 243 static struct cpufreq_driver omap_driver = { 244 .flags = CPUFREQ_STICKY, 245 .verify = omap_verify_speed, 246 .target = omap_target, 247 .get = omap_getspeed, 248 .init = omap_cpu_init, 249 .exit = omap_cpu_exit, 250 .name = "omap", 251 .attr = omap_cpufreq_attr, 252 }; 253 254 static int __init omap_cpufreq_init(void) 255 { 256 mpu_dev = get_cpu_device(0); 257 if (!mpu_dev) { 258 pr_warning("%s: unable to get the mpu device\n", __func__); 259 return -EINVAL; 260 } 261 262 mpu_reg = regulator_get(mpu_dev, "vcc"); 263 if (IS_ERR(mpu_reg)) { 264 pr_warning("%s: unable to get MPU regulator\n", __func__); 265 mpu_reg = NULL; 266 } else { 267 /* 268 * Ensure physical regulator is present. 269 * (e.g. could be dummy regulator.) 270 */ 271 if (regulator_get_voltage(mpu_reg) < 0) { 272 pr_warn("%s: physical regulator not present for MPU\n", 273 __func__); 274 regulator_put(mpu_reg); 275 mpu_reg = NULL; 276 } 277 } 278 279 return cpufreq_register_driver(&omap_driver); 280 } 281 282 static void __exit omap_cpufreq_exit(void) 283 { 284 cpufreq_unregister_driver(&omap_driver); 285 } 286 287 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs"); 288 MODULE_LICENSE("GPL"); 289 module_init(omap_cpufreq_init); 290 module_exit(omap_cpufreq_exit); 291