1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * CPU frequency scaling for DaVinci 4 * 5 * Copyright (C) 2009 Texas Instruments Incorporated - https://www.ti.com/ 6 * 7 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows: 8 * 9 * Copyright (C) 2005 Nokia Corporation 10 * Written by Tony Lindgren <tony@atomide.com> 11 * 12 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King 13 * 14 * Copyright (C) 2007-2008 Texas Instruments, Inc. 15 * Updated to support OMAP3 16 * Rajendra Nayak <rnayak@ti.com> 17 */ 18 #include <linux/types.h> 19 #include <linux/cpufreq.h> 20 #include <linux/init.h> 21 #include <linux/err.h> 22 #include <linux/clk.h> 23 #include <linux/platform_data/davinci-cpufreq.h> 24 #include <linux/platform_device.h> 25 #include <linux/export.h> 26 27 struct davinci_cpufreq { 28 struct device *dev; 29 struct clk *armclk; 30 struct clk *asyncclk; 31 unsigned long asyncrate; 32 }; 33 static struct davinci_cpufreq cpufreq; 34 35 static int davinci_target(struct cpufreq_policy *policy, unsigned int idx) 36 { 37 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 38 struct clk *armclk = cpufreq.armclk; 39 unsigned int old_freq, new_freq; 40 int ret = 0; 41 42 old_freq = policy->cur; 43 new_freq = pdata->freq_table[idx].frequency; 44 45 /* if moving to higher frequency, up the voltage beforehand */ 46 if (pdata->set_voltage && new_freq > old_freq) { 47 ret = pdata->set_voltage(idx); 48 if (ret) 49 return ret; 50 } 51 52 ret = clk_set_rate(armclk, new_freq * 1000); 53 if (ret) 54 return ret; 55 56 if (cpufreq.asyncclk) { 57 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate); 58 if (ret) 59 return ret; 60 } 61 62 /* if moving to lower freq, lower the voltage after lowering freq */ 63 if (pdata->set_voltage && new_freq < old_freq) 64 pdata->set_voltage(idx); 65 66 return 0; 67 } 68 69 static int davinci_cpu_init(struct cpufreq_policy *policy) 70 { 71 int result = 0; 72 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; 73 struct cpufreq_frequency_table *freq_table = pdata->freq_table; 74 75 if (policy->cpu != 0) 76 return -EINVAL; 77 78 /* Finish platform specific initialization */ 79 if (pdata->init) { 80 result = pdata->init(); 81 if (result) 82 return result; 83 } 84 85 policy->clk = cpufreq.armclk; 86 87 /* 88 * Time measurement across the target() function yields ~1500-1800us 89 * time taken with no drivers on notification list. 90 * Setting the latency to 2000 us to accommodate addition of drivers 91 * to pre/post change notification list. 92 */ 93 cpufreq_generic_init(policy, freq_table, 2000 * 1000); 94 return 0; 95 } 96 97 static struct cpufreq_driver davinci_driver = { 98 .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, 99 .verify = cpufreq_generic_frequency_table_verify, 100 .target_index = davinci_target, 101 .get = cpufreq_generic_get, 102 .init = davinci_cpu_init, 103 .name = "davinci", 104 .attr = cpufreq_generic_attr, 105 }; 106 107 static int __init davinci_cpufreq_probe(struct platform_device *pdev) 108 { 109 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; 110 struct clk *asyncclk; 111 112 if (!pdata) 113 return -EINVAL; 114 if (!pdata->freq_table) 115 return -EINVAL; 116 117 cpufreq.dev = &pdev->dev; 118 119 cpufreq.armclk = clk_get(NULL, "arm"); 120 if (IS_ERR(cpufreq.armclk)) { 121 dev_err(cpufreq.dev, "Unable to get ARM clock\n"); 122 return PTR_ERR(cpufreq.armclk); 123 } 124 125 asyncclk = clk_get(cpufreq.dev, "async"); 126 if (!IS_ERR(asyncclk)) { 127 cpufreq.asyncclk = asyncclk; 128 cpufreq.asyncrate = clk_get_rate(asyncclk); 129 } 130 131 return cpufreq_register_driver(&davinci_driver); 132 } 133 134 static int __exit davinci_cpufreq_remove(struct platform_device *pdev) 135 { 136 cpufreq_unregister_driver(&davinci_driver); 137 138 clk_put(cpufreq.armclk); 139 140 if (cpufreq.asyncclk) 141 clk_put(cpufreq.asyncclk); 142 143 return 0; 144 } 145 146 static struct platform_driver davinci_cpufreq_driver = { 147 .driver = { 148 .name = "cpufreq-davinci", 149 }, 150 .remove = __exit_p(davinci_cpufreq_remove), 151 }; 152 153 int __init davinci_cpufreq_init(void) 154 { 155 return platform_driver_probe(&davinci_cpufreq_driver, 156 davinci_cpufreq_probe); 157 } 158 159