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_cpu_limits(policy); 54 policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000; 55 policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000; 56 cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, 57 policy->cpuinfo.max_freq); 58 return 0; 59 } 60 61 static int davinci_target(struct cpufreq_policy *policy, unsigned int idx) 62 { 63 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 64 struct clk *armclk = cpufreq.armclk; 65 unsigned int old_freq, new_freq; 66 int ret = 0; 67 68 old_freq = policy->cur; 69 new_freq = pdata->freq_table[idx].frequency; 70 71 /* if moving to higher frequency, up the voltage beforehand */ 72 if (pdata->set_voltage && new_freq > old_freq) { 73 ret = pdata->set_voltage(idx); 74 if (ret) 75 return ret; 76 } 77 78 ret = clk_set_rate(armclk, idx); 79 if (ret) 80 return ret; 81 82 if (cpufreq.asyncclk) { 83 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate); 84 if (ret) 85 return ret; 86 } 87 88 /* if moving to lower freq, lower the voltage after lowering freq */ 89 if (pdata->set_voltage && new_freq < old_freq) 90 pdata->set_voltage(idx); 91 92 return 0; 93 } 94 95 static int davinci_cpu_init(struct cpufreq_policy *policy) 96 { 97 int result = 0; 98 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 99 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 100 101 if (policy->cpu != 0) 102 return -EINVAL; 103 104 /* Finish platform specific initialization */ 105 if (pdata->init) { 106 result = pdata->init(); 107 if (result) 108 return result; 109 } 110 111 policy->clk = cpufreq.armclk; 112 113 /* 114 * Time measurement across the target() function yields ~1500-1800us 115 * time taken with no drivers on notification list. 116 * Setting the latency to 2000 us to accommodate addition of drivers 117 * to pre/post change notification list. 118 */ 119 return cpufreq_generic_init(policy, freq_table, 2000 * 1000); 120 } 121 122 static struct cpufreq_driver davinci_driver = { 123 .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK, 124 .verify = davinci_verify_speed, 125 .target_index = davinci_target, 126 .get = cpufreq_generic_get, 127 .init = davinci_cpu_init, 128 .name = "davinci", 129 .attr = cpufreq_generic_attr, 130 }; 131 132 static int __init davinci_cpufreq_probe(struct platform_device *pdev) 133 { 134 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; 135 struct clk *asyncclk; 136 137 if (!pdata) 138 return -EINVAL; 139 if (!pdata->freq_table) 140 return -EINVAL; 141 142 cpufreq.dev = &pdev->dev; 143 144 cpufreq.armclk = clk_get(NULL, "arm"); 145 if (IS_ERR(cpufreq.armclk)) { 146 dev_err(cpufreq.dev, "Unable to get ARM clock\n"); 147 return PTR_ERR(cpufreq.armclk); 148 } 149 150 asyncclk = clk_get(cpufreq.dev, "async"); 151 if (!IS_ERR(asyncclk)) { 152 cpufreq.asyncclk = asyncclk; 153 cpufreq.asyncrate = clk_get_rate(asyncclk); 154 } 155 156 return cpufreq_register_driver(&davinci_driver); 157 } 158 159 static int __exit davinci_cpufreq_remove(struct platform_device *pdev) 160 { 161 clk_put(cpufreq.armclk); 162 163 if (cpufreq.asyncclk) 164 clk_put(cpufreq.asyncclk); 165 166 return cpufreq_unregister_driver(&davinci_driver); 167 } 168 169 static struct platform_driver davinci_cpufreq_driver = { 170 .driver = { 171 .name = "cpufreq-davinci", 172 }, 173 .remove = __exit_p(davinci_cpufreq_remove), 174 }; 175 176 int __init davinci_cpufreq_init(void) 177 { 178 return platform_driver_probe(&davinci_cpufreq_driver, 179 davinci_cpufreq_probe); 180 } 181 182