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 struct davinci_cpufreq { 34 struct device *dev; 35 struct clk *armclk; 36 struct clk *asyncclk; 37 unsigned long asyncrate; 38 }; 39 static struct davinci_cpufreq cpufreq; 40 41 static int davinci_verify_speed(struct cpufreq_policy *policy) 42 { 43 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 44 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 45 struct clk *armclk = cpufreq.armclk; 46 47 if (freq_table) 48 return cpufreq_frequency_table_verify(policy, freq_table); 49 50 if (policy->cpu) 51 return -EINVAL; 52 53 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, 54 policy->cpuinfo.max_freq); 55 56 policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000; 57 policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000; 58 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, 59 policy->cpuinfo.max_freq); 60 return 0; 61 } 62 63 static unsigned int davinci_getspeed(unsigned int cpu) 64 { 65 if (cpu) 66 return 0; 67 68 return clk_get_rate(cpufreq.armclk) / 1000; 69 } 70 71 static int davinci_target(struct cpufreq_policy *policy, 72 unsigned int target_freq, unsigned int relation) 73 { 74 int ret = 0; 75 unsigned int idx; 76 struct cpufreq_freqs freqs; 77 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 78 struct clk *armclk = cpufreq.armclk; 79 80 freqs.old = davinci_getspeed(0); 81 freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000; 82 83 if (freqs.old == freqs.new) 84 return ret; 85 86 dev_dbg(cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new); 87 88 ret = cpufreq_frequency_table_target(policy, pdata->freq_table, 89 freqs.new, relation, &idx); 90 if (ret) 91 return -EINVAL; 92 93 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); 94 95 /* if moving to higher frequency, up the voltage beforehand */ 96 if (pdata->set_voltage && freqs.new > freqs.old) { 97 ret = pdata->set_voltage(idx); 98 if (ret) 99 goto out; 100 } 101 102 ret = clk_set_rate(armclk, idx); 103 if (ret) 104 goto out; 105 106 if (cpufreq.asyncclk) { 107 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate); 108 if (ret) 109 goto out; 110 } 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 out: 117 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); 118 119 return ret; 120 } 121 122 static int davinci_cpu_init(struct cpufreq_policy *policy) 123 { 124 int result = 0; 125 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 126 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 127 128 if (policy->cpu != 0) 129 return -EINVAL; 130 131 /* Finish platform specific initialization */ 132 if (pdata->init) { 133 result = pdata->init(); 134 if (result) 135 return result; 136 } 137 138 policy->cur = davinci_getspeed(0); 139 140 result = cpufreq_frequency_table_cpuinfo(policy, freq_table); 141 if (result) { 142 pr_err("%s: cpufreq_frequency_table_cpuinfo() failed", 143 __func__); 144 return result; 145 } 146 147 cpufreq_frequency_table_get_attr(freq_table, policy->cpu); 148 149 /* 150 * Time measurement across the target() function yields ~1500-1800us 151 * time taken with no drivers on notification list. 152 * Setting the latency to 2000 us to accommodate addition of drivers 153 * to pre/post change notification list. 154 */ 155 policy->cpuinfo.transition_latency = 2000 * 1000; 156 return 0; 157 } 158 159 static int davinci_cpu_exit(struct cpufreq_policy *policy) 160 { 161 cpufreq_frequency_table_put_attr(policy->cpu); 162 return 0; 163 } 164 165 static struct freq_attr *davinci_cpufreq_attr[] = { 166 &cpufreq_freq_attr_scaling_available_freqs, 167 NULL, 168 }; 169 170 static struct cpufreq_driver davinci_driver = { 171 .flags = CPUFREQ_STICKY, 172 .verify = davinci_verify_speed, 173 .target = davinci_target, 174 .get = davinci_getspeed, 175 .init = davinci_cpu_init, 176 .exit = davinci_cpu_exit, 177 .name = "davinci", 178 .attr = davinci_cpufreq_attr, 179 }; 180 181 static int __init davinci_cpufreq_probe(struct platform_device *pdev) 182 { 183 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; 184 struct clk *asyncclk; 185 186 if (!pdata) 187 return -EINVAL; 188 if (!pdata->freq_table) 189 return -EINVAL; 190 191 cpufreq.dev = &pdev->dev; 192 193 cpufreq.armclk = clk_get(NULL, "arm"); 194 if (IS_ERR(cpufreq.armclk)) { 195 dev_err(cpufreq.dev, "Unable to get ARM clock\n"); 196 return PTR_ERR(cpufreq.armclk); 197 } 198 199 asyncclk = clk_get(cpufreq.dev, "async"); 200 if (!IS_ERR(asyncclk)) { 201 cpufreq.asyncclk = asyncclk; 202 cpufreq.asyncrate = clk_get_rate(asyncclk); 203 } 204 205 return cpufreq_register_driver(&davinci_driver); 206 } 207 208 static int __exit davinci_cpufreq_remove(struct platform_device *pdev) 209 { 210 clk_put(cpufreq.armclk); 211 212 if (cpufreq.asyncclk) 213 clk_put(cpufreq.asyncclk); 214 215 return cpufreq_unregister_driver(&davinci_driver); 216 } 217 218 static struct platform_driver davinci_cpufreq_driver = { 219 .driver = { 220 .name = "cpufreq-davinci", 221 .owner = THIS_MODULE, 222 }, 223 .remove = __exit_p(davinci_cpufreq_remove), 224 }; 225 226 int __init davinci_cpufreq_init(void) 227 { 228 return platform_driver_probe(&davinci_cpufreq_driver, 229 davinci_cpufreq_probe); 230 } 231 232