1/* 2 * CPU frequency scaling for DaVinci 3 * 4 * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/ 5 * 6 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows: 7 * 8 * Copyright (C) 2005 Nokia Corporation 9 * Written by Tony Lindgren <tony@atomide.com> 10 * 11 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King 12 * 13 * Copyright (C) 2007-2008 Texas Instruments, Inc. 14 * Updated to support OMAP3 15 * Rajendra Nayak <rnayak@ti.com> 16 * 17 * This program is free software; you can redistribute it and/or modify 18 * it under the terms of the GNU General Public License version 2 as 19 * published by the Free Software Foundation. 20 */ 21#include <linux/types.h> 22#include <linux/cpufreq.h> 23#include <linux/init.h> 24#include <linux/err.h> 25#include <linux/clk.h> 26#include <linux/platform_device.h> 27#include <linux/export.h> 28 29#include <mach/hardware.h> 30#include <mach/cpufreq.h> 31#include <mach/common.h> 32 33#include "clock.h" 34 35struct davinci_cpufreq { 36 struct device *dev; 37 struct clk *armclk; 38 struct clk *asyncclk; 39 unsigned long asyncrate; 40}; 41static struct davinci_cpufreq cpufreq; 42 43static int davinci_verify_speed(struct cpufreq_policy *policy) 44{ 45 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 46 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 47 struct clk *armclk = cpufreq.armclk; 48 49 if (freq_table) 50 return cpufreq_frequency_table_verify(policy, freq_table); 51 52 if (policy->cpu) 53 return -EINVAL; 54 55 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, 56 policy->cpuinfo.max_freq); 57 58 policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000; 59 policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000; 60 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, 61 policy->cpuinfo.max_freq); 62 return 0; 63} 64 65static unsigned int davinci_getspeed(unsigned int cpu) 66{ 67 if (cpu) 68 return 0; 69 70 return clk_get_rate(cpufreq.armclk) / 1000; 71} 72 73static int davinci_target(struct cpufreq_policy *policy, 74 unsigned int target_freq, unsigned int relation) 75{ 76 int ret = 0; 77 unsigned int idx; 78 struct cpufreq_freqs freqs; 79 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 80 struct clk *armclk = cpufreq.armclk; 81 82 /* 83 * Ensure desired rate is within allowed range. Some govenors 84 * (ondemand) will just pass target_freq=0 to get the minimum. 85 */ 86 if (target_freq < policy->cpuinfo.min_freq) 87 target_freq = policy->cpuinfo.min_freq; 88 if (target_freq > policy->cpuinfo.max_freq) 89 target_freq = policy->cpuinfo.max_freq; 90 91 freqs.old = davinci_getspeed(0); 92 freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000; 93 freqs.cpu = 0; 94 95 if (freqs.old == freqs.new) 96 return ret; 97 98 dev_dbg(cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new); 99 100 ret = cpufreq_frequency_table_target(policy, pdata->freq_table, 101 freqs.new, relation, &idx); 102 if (ret) 103 return -EINVAL; 104 105 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); 106 107 /* if moving to higher frequency, up the voltage beforehand */ 108 if (pdata->set_voltage && freqs.new > freqs.old) { 109 ret = pdata->set_voltage(idx); 110 if (ret) 111 goto out; 112 } 113 114 ret = clk_set_rate(armclk, idx); 115 if (ret) 116 goto out; 117 118 if (cpufreq.asyncclk) { 119 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate); 120 if (ret) 121 goto out; 122 } 123 124 /* if moving to lower freq, lower the voltage after lowering freq */ 125 if (pdata->set_voltage && freqs.new < freqs.old) 126 pdata->set_voltage(idx); 127 128out: 129 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); 130 131 return ret; 132} 133 134static int davinci_cpu_init(struct cpufreq_policy *policy) 135{ 136 int result = 0; 137 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 138 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 139 140 if (policy->cpu != 0) 141 return -EINVAL; 142 143 /* Finish platform specific initialization */ 144 if (pdata->init) { 145 result = pdata->init(); 146 if (result) 147 return result; 148 } 149 150 policy->cur = policy->min = policy->max = davinci_getspeed(0); 151 152 if (freq_table) { 153 result = cpufreq_frequency_table_cpuinfo(policy, freq_table); 154 if (!result) 155 cpufreq_frequency_table_get_attr(freq_table, 156 policy->cpu); 157 } else { 158 policy->cpuinfo.min_freq = policy->min; 159 policy->cpuinfo.max_freq = policy->max; 160 } 161 162 policy->min = policy->cpuinfo.min_freq; 163 policy->max = policy->cpuinfo.max_freq; 164 policy->cur = davinci_getspeed(0); 165 166 /* 167 * Time measurement across the target() function yields ~1500-1800us 168 * time taken with no drivers on notification list. 169 * Setting the latency to 2000 us to accommodate addition of drivers 170 * to pre/post change notification list. 171 */ 172 policy->cpuinfo.transition_latency = 2000 * 1000; 173 return 0; 174} 175 176static int davinci_cpu_exit(struct cpufreq_policy *policy) 177{ 178 cpufreq_frequency_table_put_attr(policy->cpu); 179 return 0; 180} 181 182static struct freq_attr *davinci_cpufreq_attr[] = { 183 &cpufreq_freq_attr_scaling_available_freqs, 184 NULL, 185}; 186 187static struct cpufreq_driver davinci_driver = { 188 .flags = CPUFREQ_STICKY, 189 .verify = davinci_verify_speed, 190 .target = davinci_target, 191 .get = davinci_getspeed, 192 .init = davinci_cpu_init, 193 .exit = davinci_cpu_exit, 194 .name = "davinci", 195 .attr = davinci_cpufreq_attr, 196}; 197 198static int __init davinci_cpufreq_probe(struct platform_device *pdev) 199{ 200 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; 201 struct clk *asyncclk; 202 203 if (!pdata) 204 return -EINVAL; 205 if (!pdata->freq_table) 206 return -EINVAL; 207 208 cpufreq.dev = &pdev->dev; 209 210 cpufreq.armclk = clk_get(NULL, "arm"); 211 if (IS_ERR(cpufreq.armclk)) { 212 dev_err(cpufreq.dev, "Unable to get ARM clock\n"); 213 return PTR_ERR(cpufreq.armclk); 214 } 215 216 asyncclk = clk_get(cpufreq.dev, "async"); 217 if (!IS_ERR(asyncclk)) { 218 cpufreq.asyncclk = asyncclk; 219 cpufreq.asyncrate = clk_get_rate(asyncclk); 220 } 221 222 return cpufreq_register_driver(&davinci_driver); 223} 224 225static int __exit davinci_cpufreq_remove(struct platform_device *pdev) 226{ 227 clk_put(cpufreq.armclk); 228 229 if (cpufreq.asyncclk) 230 clk_put(cpufreq.asyncclk); 231 232 return cpufreq_unregister_driver(&davinci_driver); 233} 234 235static struct platform_driver davinci_cpufreq_driver = { 236 .driver = { 237 .name = "cpufreq-davinci", 238 .owner = THIS_MODULE, 239 }, 240 .remove = __exit_p(davinci_cpufreq_remove), 241}; 242 243static int __init davinci_cpufreq_init(void) 244{ 245 return platform_driver_probe(&davinci_cpufreq_driver, 246 davinci_cpufreq_probe); 247} 248late_initcall(davinci_cpufreq_init); 249 250