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_target(struct cpufreq_policy *policy, unsigned int idx) 42 { 43 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 44 struct clk *armclk = cpufreq.armclk; 45 unsigned int old_freq, new_freq; 46 int ret = 0; 47 48 old_freq = policy->cur; 49 new_freq = pdata->freq_table[idx].frequency; 50 51 /* if moving to higher frequency, up the voltage beforehand */ 52 if (pdata->set_voltage && new_freq > old_freq) { 53 ret = pdata->set_voltage(idx); 54 if (ret) 55 return ret; 56 } 57 58 ret = clk_set_rate(armclk, idx); 59 if (ret) 60 return ret; 61 62 if (cpufreq.asyncclk) { 63 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate); 64 if (ret) 65 return ret; 66 } 67 68 /* if moving to lower freq, lower the voltage after lowering freq */ 69 if (pdata->set_voltage && new_freq < old_freq) 70 pdata->set_voltage(idx); 71 72 return 0; 73 } 74 75 static int davinci_cpu_init(struct cpufreq_policy *policy) 76 { 77 int result = 0; 78 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 79 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 80 81 if (policy->cpu != 0) 82 return -EINVAL; 83 84 /* Finish platform specific initialization */ 85 if (pdata->init) { 86 result = pdata->init(); 87 if (result) 88 return result; 89 } 90 91 policy->clk = cpufreq.armclk; 92 93 /* 94 * Time measurement across the target() function yields ~1500-1800us 95 * time taken with no drivers on notification list. 96 * Setting the latency to 2000 us to accommodate addition of drivers 97 * to pre/post change notification list. 98 */ 99 return cpufreq_generic_init(policy, freq_table, 2000 * 1000); 100 } 101 102 static struct cpufreq_driver davinci_driver = { 103 .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK, 104 .verify = cpufreq_generic_frequency_table_verify, 105 .target_index = davinci_target, 106 .get = cpufreq_generic_get, 107 .init = davinci_cpu_init, 108 .name = "davinci", 109 .attr = cpufreq_generic_attr, 110 }; 111 112 static int __init davinci_cpufreq_probe(struct platform_device *pdev) 113 { 114 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; 115 struct clk *asyncclk; 116 117 if (!pdata) 118 return -EINVAL; 119 if (!pdata->freq_table) 120 return -EINVAL; 121 122 cpufreq.dev = &pdev->dev; 123 124 cpufreq.armclk = clk_get(NULL, "arm"); 125 if (IS_ERR(cpufreq.armclk)) { 126 dev_err(cpufreq.dev, "Unable to get ARM clock\n"); 127 return PTR_ERR(cpufreq.armclk); 128 } 129 130 asyncclk = clk_get(cpufreq.dev, "async"); 131 if (!IS_ERR(asyncclk)) { 132 cpufreq.asyncclk = asyncclk; 133 cpufreq.asyncrate = clk_get_rate(asyncclk); 134 } 135 136 return cpufreq_register_driver(&davinci_driver); 137 } 138 139 static int __exit davinci_cpufreq_remove(struct platform_device *pdev) 140 { 141 clk_put(cpufreq.armclk); 142 143 if (cpufreq.asyncclk) 144 clk_put(cpufreq.asyncclk); 145 146 return cpufreq_unregister_driver(&davinci_driver); 147 } 148 149 static struct platform_driver davinci_cpufreq_driver = { 150 .driver = { 151 .name = "cpufreq-davinci", 152 }, 153 .remove = __exit_p(davinci_cpufreq_remove), 154 }; 155 156 int __init davinci_cpufreq_init(void) 157 { 158 return platform_driver_probe(&davinci_cpufreq_driver, 159 davinci_cpufreq_probe); 160 } 161 162