![Sekhar Nori](/assets/img/avatar_default.png)
On OMAP-L138 SoC, some of the sysclks need not be at a fixed ratio to CPU clock and can be kept at a relatively constant rate by adjusting the PLLDIVn ratio even as cpufreq goes ahead and changes the CPU clock. This feature can be used to keep the EMIFA (PLL0 SYSCLK3) clock at a constant rate so that the EMIF timings need not be re-programmed whenever the CPU frequency changes. This patch adds the required suppport to cpufreq driver. Signed-off-by: Sekhar Nori <nsekhar@ti.com> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
251 lines
6.2 KiB
C
251 lines
6.2 KiB
C
/*
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* CPU frequency scaling for DaVinci
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*
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* Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
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*
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* Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
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*
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* Copyright (C) 2005 Nokia Corporation
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* Written by Tony Lindgren <tony@atomide.com>
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*
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* Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
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*
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* Copyright (C) 2007-2008 Texas Instruments, Inc.
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* Updated to support OMAP3
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* Rajendra Nayak <rnayak@ti.com>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/types.h>
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#include <linux/cpufreq.h>
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#include <linux/init.h>
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#include <linux/err.h>
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#include <linux/clk.h>
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#include <linux/platform_device.h>
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#include <mach/hardware.h>
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#include <mach/cpufreq.h>
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#include <mach/common.h>
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#include "clock.h"
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struct davinci_cpufreq {
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struct device *dev;
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struct clk *armclk;
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struct clk *asyncclk;
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unsigned long asyncrate;
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};
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static struct davinci_cpufreq cpufreq;
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static int davinci_verify_speed(struct cpufreq_policy *policy)
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{
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struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
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struct cpufreq_frequency_table *freq_table = pdata->freq_table;
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struct clk *armclk = cpufreq.armclk;
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if (freq_table)
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return cpufreq_frequency_table_verify(policy, freq_table);
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if (policy->cpu)
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return -EINVAL;
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cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
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policy->cpuinfo.max_freq);
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policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
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policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
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cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
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policy->cpuinfo.max_freq);
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return 0;
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}
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static unsigned int davinci_getspeed(unsigned int cpu)
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{
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if (cpu)
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return 0;
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return clk_get_rate(cpufreq.armclk) / 1000;
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}
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static int davinci_target(struct cpufreq_policy *policy,
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unsigned int target_freq, unsigned int relation)
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{
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int ret = 0;
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unsigned int idx;
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struct cpufreq_freqs freqs;
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struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
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struct clk *armclk = cpufreq.armclk;
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/*
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* Ensure desired rate is within allowed range. Some govenors
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* (ondemand) will just pass target_freq=0 to get the minimum.
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*/
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if (target_freq < policy->cpuinfo.min_freq)
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target_freq = policy->cpuinfo.min_freq;
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if (target_freq > policy->cpuinfo.max_freq)
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target_freq = policy->cpuinfo.max_freq;
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freqs.old = davinci_getspeed(0);
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freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
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freqs.cpu = 0;
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if (freqs.old == freqs.new)
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return ret;
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cpufreq_debug_printk(CPUFREQ_DEBUG_DRIVER,
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dev_driver_string(cpufreq.dev),
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"transition: %u --> %u\n", freqs.old, freqs.new);
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ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
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freqs.new, relation, &idx);
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if (ret)
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return -EINVAL;
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cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
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/* if moving to higher frequency, up the voltage beforehand */
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if (pdata->set_voltage && freqs.new > freqs.old) {
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ret = pdata->set_voltage(idx);
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if (ret)
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goto out;
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}
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ret = clk_set_rate(armclk, idx);
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if (ret)
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goto out;
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if (cpufreq.asyncclk) {
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ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
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if (ret)
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goto out;
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}
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/* if moving to lower freq, lower the voltage after lowering freq */
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if (pdata->set_voltage && freqs.new < freqs.old)
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pdata->set_voltage(idx);
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out:
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cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
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return ret;
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}
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static int __init davinci_cpu_init(struct cpufreq_policy *policy)
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{
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int result = 0;
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struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
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struct cpufreq_frequency_table *freq_table = pdata->freq_table;
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if (policy->cpu != 0)
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return -EINVAL;
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/* Finish platform specific initialization */
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if (pdata->init) {
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result = pdata->init();
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if (result)
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return result;
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}
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policy->cur = policy->min = policy->max = davinci_getspeed(0);
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if (freq_table) {
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result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
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if (!result)
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cpufreq_frequency_table_get_attr(freq_table,
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policy->cpu);
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} else {
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policy->cpuinfo.min_freq = policy->min;
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policy->cpuinfo.max_freq = policy->max;
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}
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policy->min = policy->cpuinfo.min_freq;
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policy->max = policy->cpuinfo.max_freq;
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policy->cur = davinci_getspeed(0);
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/*
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* Time measurement across the target() function yields ~1500-1800us
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* time taken with no drivers on notification list.
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* Setting the latency to 2000 us to accomodate addition of drivers
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* to pre/post change notification list.
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*/
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policy->cpuinfo.transition_latency = 2000 * 1000;
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return 0;
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}
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static int davinci_cpu_exit(struct cpufreq_policy *policy)
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{
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cpufreq_frequency_table_put_attr(policy->cpu);
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return 0;
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}
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static struct freq_attr *davinci_cpufreq_attr[] = {
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&cpufreq_freq_attr_scaling_available_freqs,
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NULL,
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};
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static struct cpufreq_driver davinci_driver = {
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.flags = CPUFREQ_STICKY,
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.verify = davinci_verify_speed,
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.target = davinci_target,
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.get = davinci_getspeed,
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.init = davinci_cpu_init,
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.exit = davinci_cpu_exit,
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.name = "davinci",
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.attr = davinci_cpufreq_attr,
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};
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static int __init davinci_cpufreq_probe(struct platform_device *pdev)
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{
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struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
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struct clk *asyncclk;
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if (!pdata)
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return -EINVAL;
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if (!pdata->freq_table)
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return -EINVAL;
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cpufreq.dev = &pdev->dev;
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cpufreq.armclk = clk_get(NULL, "arm");
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if (IS_ERR(cpufreq.armclk)) {
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dev_err(cpufreq.dev, "Unable to get ARM clock\n");
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return PTR_ERR(cpufreq.armclk);
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}
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asyncclk = clk_get(cpufreq.dev, "async");
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if (!IS_ERR(asyncclk)) {
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cpufreq.asyncclk = asyncclk;
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cpufreq.asyncrate = clk_get_rate(asyncclk);
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}
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return cpufreq_register_driver(&davinci_driver);
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}
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static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
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{
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clk_put(cpufreq.armclk);
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if (cpufreq.asyncclk)
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clk_put(cpufreq.asyncclk);
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return cpufreq_unregister_driver(&davinci_driver);
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}
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static struct platform_driver davinci_cpufreq_driver = {
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.driver = {
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.name = "cpufreq-davinci",
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.owner = THIS_MODULE,
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},
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.remove = __exit_p(davinci_cpufreq_remove),
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};
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static int __init davinci_cpufreq_init(void)
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{
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return platform_driver_probe(&davinci_cpufreq_driver,
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davinci_cpufreq_probe);
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}
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late_initcall(davinci_cpufreq_init);
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