/* * CPU frequency scaling for DaVinci * * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/ * * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows: * * Copyright (C) 2005 Nokia Corporation * Written by Tony Lindgren <tony@atomide.com> * * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King * * Copyright (C) 2007-2008 Texas Instruments, Inc. * Updated to support OMAP3 * Rajendra Nayak <rnayak@ti.com> * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. */ #include <linux/types.h> #include <linux/cpufreq.h> #include <linux/init.h> #include <linux/err.h> #include <linux/clk.h> #include <linux/platform_device.h> #include <linux/export.h> #include <mach/hardware.h> #include <mach/cpufreq.h> #include <mach/common.h> struct davinci_cpufreq { struct device *dev; struct clk *armclk; struct clk *asyncclk; unsigned long asyncrate; }; static struct davinci_cpufreq cpufreq; static int davinci_verify_speed(struct cpufreq_policy *policy) { struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; struct cpufreq_frequency_table *freq_table = pdata->freq_table; struct clk *armclk = cpufreq.armclk; if (freq_table) return cpufreq_frequency_table_verify(policy, freq_table); if (policy->cpu) return -EINVAL; cpufreq_verify_within_cpu_limits(policy); policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000; policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000; cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq, policy->cpuinfo.max_freq); return 0; } static int davinci_target(struct cpufreq_policy *policy, unsigned int idx) { struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; struct clk *armclk = cpufreq.armclk; unsigned int old_freq, new_freq; int ret = 0; old_freq = policy->cur; new_freq = pdata->freq_table[idx].frequency; /* if moving to higher frequency, up the voltage beforehand */ if (pdata->set_voltage && new_freq > old_freq) { ret = pdata->set_voltage(idx); if (ret) return ret; } ret = clk_set_rate(armclk, idx); if (ret) return ret; if (cpufreq.asyncclk) { ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate); if (ret) return ret; } /* if moving to lower freq, lower the voltage after lowering freq */ if (pdata->set_voltage && new_freq < old_freq) pdata->set_voltage(idx); return 0; } static int davinci_cpu_init(struct cpufreq_policy *policy) { int result = 0; struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data; struct cpufreq_frequency_table *freq_table = pdata->freq_table; if (policy->cpu != 0) return -EINVAL; /* Finish platform specific initialization */ if (pdata->init) { result = pdata->init(); if (result) return result; } policy->clk = cpufreq.armclk; /* * Time measurement across the target() function yields ~1500-1800us * time taken with no drivers on notification list. * Setting the latency to 2000 us to accommodate addition of drivers * to pre/post change notification list. */ return cpufreq_generic_init(policy, freq_table, 2000 * 1000); } static struct cpufreq_driver davinci_driver = { .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK, .verify = davinci_verify_speed, .target_index = davinci_target, .get = cpufreq_generic_get, .init = davinci_cpu_init, .name = "davinci", .attr = cpufreq_generic_attr, }; static int __init davinci_cpufreq_probe(struct platform_device *pdev) { struct davinci_cpufreq_config *pdata = pdev->dev.platform_data; struct clk *asyncclk; if (!pdata) return -EINVAL; if (!pdata->freq_table) return -EINVAL; cpufreq.dev = &pdev->dev; cpufreq.armclk = clk_get(NULL, "arm"); if (IS_ERR(cpufreq.armclk)) { dev_err(cpufreq.dev, "Unable to get ARM clock\n"); return PTR_ERR(cpufreq.armclk); } asyncclk = clk_get(cpufreq.dev, "async"); if (!IS_ERR(asyncclk)) { cpufreq.asyncclk = asyncclk; cpufreq.asyncrate = clk_get_rate(asyncclk); } return cpufreq_register_driver(&davinci_driver); } static int __exit davinci_cpufreq_remove(struct platform_device *pdev) { clk_put(cpufreq.armclk); if (cpufreq.asyncclk) clk_put(cpufreq.asyncclk); return cpufreq_unregister_driver(&davinci_driver); } static struct platform_driver davinci_cpufreq_driver = { .driver = { .name = "cpufreq-davinci", .owner = THIS_MODULE, }, .remove = __exit_p(davinci_cpufreq_remove), }; int __init davinci_cpufreq_init(void) { return platform_driver_probe(&davinci_cpufreq_driver, davinci_cpufreq_probe); }