157 lines
3.8 KiB
C
157 lines
3.8 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* CPU frequency scaling for DaVinci
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*
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* Copyright (C) 2009 Texas Instruments Incorporated - https://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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#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_data/davinci-cpufreq.h>
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#include <linux/platform_device.h>
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#include <linux/export.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_target(struct cpufreq_policy *policy, unsigned int idx)
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{
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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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unsigned int old_freq, new_freq;
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int ret = 0;
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old_freq = policy->cur;
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new_freq = pdata->freq_table[idx].frequency;
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/* if moving to higher frequency, up the voltage beforehand */
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if (pdata->set_voltage && new_freq > old_freq) {
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ret = pdata->set_voltage(idx);
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if (ret)
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return ret;
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}
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ret = clk_set_rate(armclk, new_freq * 1000);
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if (ret)
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return ret;
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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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return ret;
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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 && new_freq < old_freq)
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pdata->set_voltage(idx);
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return 0;
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}
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static int 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->clk = cpufreq.armclk;
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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 accommodate addition of drivers
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* to pre/post change notification list.
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*/
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cpufreq_generic_init(policy, freq_table, 2000 * 1000);
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return 0;
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}
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static struct cpufreq_driver davinci_driver = {
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.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
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.verify = cpufreq_generic_frequency_table_verify,
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.target_index = davinci_target,
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.get = cpufreq_generic_get,
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.init = davinci_cpu_init,
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.name = "davinci",
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.attr = cpufreq_generic_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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},
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.remove = __exit_p(davinci_cpufreq_remove),
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};
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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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