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9076eaca60
As multiplatform build is being adopted by more and more ARM platforms, initcall function should be used very carefully. For example, when both arm_big_little_dt and cpufreq-cpu0 drivers are compiled in, arm_big_little_dt driver may try to register even if we had platform device for cpufreq-cpu0 registered. To eliminate this undesired the effect, the patch changes arm_big_little_dt driver to have it instantiated as a platform_driver. Then it will only run on platforms that create the platform_device "arm-bL-cpufreq-dt". Reported-and-tested-by: Rob Herring <robherring2@gmail.com> Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
130 lines
3.0 KiB
C
130 lines
3.0 KiB
C
/*
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* Generic big.LITTLE CPUFreq Interface driver
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*
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* It provides necessary ops to arm_big_little cpufreq driver and gets
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* Frequency information from Device Tree. Freq table in DT must be in KHz.
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*
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* Copyright (C) 2013 Linaro.
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* Viresh Kumar <viresh.kumar@linaro.org>
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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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* This program is distributed "as is" WITHOUT ANY WARRANTY of any
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* kind, whether express or implied; without even the implied warranty
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* of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/cpu.h>
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#include <linux/cpufreq.h>
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#include <linux/device.h>
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#include <linux/export.h>
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#include <linux/module.h>
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#include <linux/of.h>
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#include <linux/opp.h>
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#include <linux/platform_device.h>
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#include <linux/slab.h>
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#include <linux/types.h>
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#include "arm_big_little.h"
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/* get cpu node with valid operating-points */
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static struct device_node *get_cpu_node_with_valid_op(int cpu)
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{
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struct device_node *np = NULL, *parent;
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int count = 0;
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parent = of_find_node_by_path("/cpus");
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if (!parent) {
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pr_err("failed to find OF /cpus\n");
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return NULL;
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}
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for_each_child_of_node(parent, np) {
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if (count++ != cpu)
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continue;
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if (!of_get_property(np, "operating-points", NULL)) {
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of_node_put(np);
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np = NULL;
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}
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break;
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}
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of_node_put(parent);
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return np;
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}
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static int dt_init_opp_table(struct device *cpu_dev)
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{
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struct device_node *np;
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int ret;
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np = get_cpu_node_with_valid_op(cpu_dev->id);
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if (!np)
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return -ENODATA;
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cpu_dev->of_node = np;
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ret = of_init_opp_table(cpu_dev);
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of_node_put(np);
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return ret;
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}
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static int dt_get_transition_latency(struct device *cpu_dev)
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{
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struct device_node *np;
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u32 transition_latency = CPUFREQ_ETERNAL;
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np = get_cpu_node_with_valid_op(cpu_dev->id);
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if (!np)
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return CPUFREQ_ETERNAL;
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of_property_read_u32(np, "clock-latency", &transition_latency);
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of_node_put(np);
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pr_debug("%s: clock-latency: %d\n", __func__, transition_latency);
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return transition_latency;
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}
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static struct cpufreq_arm_bL_ops dt_bL_ops = {
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.name = "dt-bl",
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.get_transition_latency = dt_get_transition_latency,
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.init_opp_table = dt_init_opp_table,
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};
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static int generic_bL_probe(struct platform_device *pdev)
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{
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struct device_node *np;
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np = get_cpu_node_with_valid_op(0);
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if (!np)
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return -ENODEV;
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of_node_put(np);
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return bL_cpufreq_register(&dt_bL_ops);
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}
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static int generic_bL_remove(struct platform_device *pdev)
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{
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bL_cpufreq_unregister(&dt_bL_ops);
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return 0;
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}
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static struct platform_driver generic_bL_platdrv = {
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.driver = {
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.name = "arm-bL-cpufreq-dt",
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.owner = THIS_MODULE,
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},
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.probe = generic_bL_probe,
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.remove = generic_bL_remove,
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};
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module_platform_driver(generic_bL_platdrv);
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MODULE_AUTHOR("Viresh Kumar <viresh.kumar@linaro.org>");
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MODULE_DESCRIPTION("Generic ARM big LITTLE cpufreq driver via DT");
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MODULE_LICENSE("GPL");
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