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3b7cbd308e
During cpufreq driver's registration, if the ->init() callback for all
the CPUs fail then there is not much point in keeping the driver around
as it will only account for more of unnecessary noise, for example
cpufreq core will try to suspend/resume the driver which never got
registered properly.
The removal of such a driver is avoided if the driver carries the
CPUFREQ_STICKY flag. This was added way back [1] in 2004 and perhaps no
one should ever need it now. A lot of drivers do set this flag, probably
because they just copied it from other drivers.
This was added earlier for some platforms [2] because their cpufreq
drivers were getting registered before the CPUs were registered with
subsys framework. And hence they used to fail.
The same isn't true anymore though. The current code flow in the kernel
is:
start_kernel()
-> kernel_init()
-> kernel_init_freeable()
-> do_basic_setup()
-> driver_init()
-> cpu_dev_init()
-> subsys_system_register() //For CPUs
-> do_initcalls()
-> cpufreq_register_driver()
Clearly, the CPUs will always get registered with subsys framework
before any cpufreq driver can get probed. Remove the flag and update the
relevant drivers.
Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/include/linux/cpufreq.h?id=7cc9f0d9a1ab04cedc60d64fd8dcf7df224a3b4d # [1]
Link: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git/commit/arch/arm/mach-sa1100/cpu-sa1100.c?id=f59d3bbe35f6268d729f51be82af8325d62f20f5 # [2]
Change-Id: If2509516ec7fa7518750e23e0198614654dbf9b7
Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Samuel Pascua <pascua.samuel.14@gmail.com>
Signed-off-by: Richard Raya <rdxzv.dev@gmail.com>
127 lines
3.0 KiB
C
127 lines
3.0 KiB
C
/*
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* Copyright (C) 2004-2007 Atmel Corporation
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*
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* Based on MIPS implementation arch/mips/kernel/time.c
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* Copyright 2001 MontaVista Software Inc.
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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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/*#define DEBUG*/
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#include <linux/kernel.h>
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#include <linux/types.h>
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#include <linux/init.h>
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#include <linux/cpufreq.h>
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#include <linux/io.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/export.h>
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#include <linux/slab.h>
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static struct cpufreq_frequency_table *freq_table;
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static unsigned int ref_freq;
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static unsigned long loops_per_jiffy_ref;
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static int at32_set_target(struct cpufreq_policy *policy, unsigned int index)
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{
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unsigned int old_freq, new_freq;
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old_freq = policy->cur;
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new_freq = freq_table[index].frequency;
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if (!ref_freq) {
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ref_freq = old_freq;
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loops_per_jiffy_ref = boot_cpu_data.loops_per_jiffy;
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}
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if (old_freq < new_freq)
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boot_cpu_data.loops_per_jiffy = cpufreq_scale(
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loops_per_jiffy_ref, ref_freq, new_freq);
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clk_set_rate(policy->clk, new_freq * 1000);
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if (new_freq < old_freq)
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boot_cpu_data.loops_per_jiffy = cpufreq_scale(
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loops_per_jiffy_ref, ref_freq, new_freq);
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return 0;
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}
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static int at32_cpufreq_driver_init(struct cpufreq_policy *policy)
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{
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unsigned int frequency, rate, min_freq;
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struct clk *cpuclk;
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int retval, steps, i;
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if (policy->cpu != 0)
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return -EINVAL;
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cpuclk = clk_get(NULL, "cpu");
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if (IS_ERR(cpuclk)) {
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pr_debug("cpufreq: could not get CPU clk\n");
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retval = PTR_ERR(cpuclk);
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goto out_err;
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}
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min_freq = (clk_round_rate(cpuclk, 1) + 500) / 1000;
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frequency = (clk_round_rate(cpuclk, ~0UL) + 500) / 1000;
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policy->cpuinfo.transition_latency = 0;
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/*
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* AVR32 CPU frequency rate scales in power of two between maximum and
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* minimum, also add space for the table end marker.
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*
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* Further validate that the frequency is usable, and append it to the
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* frequency table.
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*/
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steps = fls(frequency / min_freq) + 1;
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freq_table = kzalloc(steps * sizeof(struct cpufreq_frequency_table),
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GFP_KERNEL);
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if (!freq_table) {
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retval = -ENOMEM;
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goto out_err_put_clk;
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}
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for (i = 0; i < (steps - 1); i++) {
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rate = clk_round_rate(cpuclk, frequency * 1000) / 1000;
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if (rate != frequency)
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freq_table[i].frequency = CPUFREQ_ENTRY_INVALID;
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else
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freq_table[i].frequency = frequency;
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frequency /= 2;
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}
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policy->clk = cpuclk;
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freq_table[steps - 1].frequency = CPUFREQ_TABLE_END;
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retval = cpufreq_table_validate_and_show(policy, freq_table);
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if (!retval) {
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printk("cpufreq: AT32AP CPU frequency driver\n");
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return 0;
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}
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kfree(freq_table);
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out_err_put_clk:
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clk_put(cpuclk);
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out_err:
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return retval;
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}
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static struct cpufreq_driver at32_driver = {
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.name = "at32ap",
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.init = at32_cpufreq_driver_init,
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.verify = cpufreq_generic_frequency_table_verify,
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.target_index = at32_set_target,
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.get = cpufreq_generic_get,
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};
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static int __init at32_cpufreq_init(void)
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{
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return cpufreq_register_driver(&at32_driver);
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}
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late_initcall(at32_cpufreq_init);
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