| 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 | |