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 28#include <mach/hardware.h> 29#include <mach/cpufreq.h> 30#include <mach/common.h> 31 32#include "clock.h" 33 34struct davinci_cpufreq { 35 struct device *dev; 36 struct clk *armclk; 37}; 38static struct davinci_cpufreq cpufreq; 39 40static int davinci_verify_speed(struct cpufreq_policy *policy) 41{ 42 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 43 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 44 struct clk *armclk = cpufreq.armclk; 45 46 if (freq_table) 47 return cpufreq_frequency_table_verify(policy, freq_table); 48 49 if (policy->cpu) 50 return -EINVAL; 51 52 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, 53 policy->cpuinfo.max_freq); 54 55 policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000; 56 policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000; 57 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, 58 policy->cpuinfo.max_freq); 59 return 0; 60} 61 62static unsigned int davinci_getspeed(unsigned int cpu) 63{ 64 if (cpu) 65 return 0; 66 67 return clk_get_rate(cpufreq.armclk) / 1000; 68} 69 70static int davinci_target(struct cpufreq_policy *policy, 71 unsigned int target_freq, unsigned int relation) 72{ 73 int ret = 0; 74 unsigned int idx; 75 struct cpufreq_freqs freqs; 76 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 77 struct clk *armclk = cpufreq.armclk; 78 79 /* 80 * Ensure desired rate is within allowed range. Some govenors 81 * (ondemand) will just pass target_freq=0 to get the minimum. 82 */ 83 if (target_freq < policy->cpuinfo.min_freq) 84 target_freq = policy->cpuinfo.min_freq; 85 if (target_freq > policy->cpuinfo.max_freq) 86 target_freq = policy->cpuinfo.max_freq; 87 88 freqs.old = davinci_getspeed(0); 89 freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000; 90 freqs.cpu = 0; 91 92 if (freqs.old == freqs.new) 93 return ret; 94 95 cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER, 96 dev_driver_string(cpufreq.dev), 97 "transition: %u --> %u\n", freqs.old, freqs.new); 98 99 ret = cpufreq_frequency_table_target(policy, pdata->freq_table, 100 freqs.new, relation, &idx); 101 if (ret) 102 return -EINVAL; 103 104 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); 105 106 /* if moving to higher frequency, up the voltage beforehand */ 107 if (pdata->set_voltage && freqs.new > freqs.old) 108 pdata->set_voltage(idx); 109 110 ret = clk_set_rate(armclk, idx); 111 112 /* if moving to lower freq, lower the voltage after lowering freq */ 113 if (pdata->set_voltage && freqs.new < freqs.old) 114 pdata->set_voltage(idx); 115 116 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); 117 118 return ret; 119} 120 121static int __init davinci_cpu_init(struct cpufreq_policy *policy) 122{ 123 int result = 0; 124 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 125 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 126 127 if (policy->cpu != 0) 128 return -EINVAL; 129 130 /* Finish platform specific initialization */ 131 if (pdata->init) { 132 result = pdata->init(); 133 if (result) 134 return result; 135 } 136 137 policy->cur = policy->min = policy->max = davinci_getspeed(0); 138 139 if (freq_table) { 140 result = cpufreq_frequency_table_cpuinfo(policy, freq_table); 141 if (!result) 142 cpufreq_frequency_table_get_attr(freq_table, 143 policy->cpu); 144 } else { 145 policy->cpuinfo.min_freq = policy->min; 146 policy->cpuinfo.max_freq = policy->max; 147 } 148 149 policy->min = policy->cpuinfo.min_freq; 150 policy->max = policy->cpuinfo.max_freq; 151 policy->cur = davinci_getspeed(0); 152 153 /* 154 * Time measurement across the target() function yields ~1500-1800us 155 * time taken with no drivers on notification list. 156 * Setting the latency to 2000 us to accomodate addition of drivers 157 * to pre/post change notification list. 158 */ 159 policy->cpuinfo.transition_latency = 2000 * 1000; 160 return 0; 161} 162 163static int davinci_cpu_exit(struct cpufreq_policy *policy) 164{ 165 cpufreq_frequency_table_put_attr(policy->cpu); 166 return 0; 167} 168 169static struct freq_attr *davinci_cpufreq_attr[] = { 170 &cpufreq_freq_attr_scaling_available_freqs, 171 NULL, 172}; 173 174static struct cpufreq_driver davinci_driver = { 175 .flags = CPUFREQ_STICKY, 176 .verify = davinci_verify_speed, 177 .target = davinci_target, 178 .get = davinci_getspeed, 179 .init = davinci_cpu_init, 180 .exit = davinci_cpu_exit, 181 .name = "davinci", 182 .attr = davinci_cpufreq_attr, 183}; 184 185static int __init davinci_cpufreq_probe(struct platform_device *pdev) 186{ 187 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; 188 189 if (!pdata) 190 return -EINVAL; 191 if (!pdata->freq_table) 192 return -EINVAL; 193 194 cpufreq.dev = &pdev->dev; 195 196 cpufreq.armclk = clk_get(NULL, "arm"); 197 if (IS_ERR(cpufreq.armclk)) { 198 dev_err(cpufreq.dev, "Unable to get ARM clock\n"); 199 return PTR_ERR(cpufreq.armclk); 200 } 201 202 return cpufreq_register_driver(&davinci_driver); 203} 204 205static int __exit davinci_cpufreq_remove(struct platform_device *pdev) 206{ 207 clk_put(cpufreq.armclk); 208 209 return cpufreq_unregister_driver(&davinci_driver); 210} 211 212static struct platform_driver davinci_cpufreq_driver = { 213 .driver = { 214 .name = "cpufreq-davinci", 215 .owner = THIS_MODULE, 216 }, 217 .remove = __exit_p(davinci_cpufreq_remove), 218}; 219 220static int __init davinci_cpufreq_init(void) 221{ 222 return platform_driver_probe(&davinci_cpufreq_driver, 223 davinci_cpufreq_probe); 224} 225late_initcall(davinci_cpufreq_init); 226