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ae6b427132
Sometimes boot loaders set CPU frequency to a value outside of frequency table present with cpufreq core. In such cases CPU might be unstable if it has to run on that frequency for long duration of time and so its better to set it to a frequency which is specified in frequency table. On some systems we can't really say what frequency we're running at the moment and so for these we shouldn't check if we are running at a frequency present in frequency table. And so we really can't force this for all the cpufreq drivers. Hence we are created another flag here: CPUFREQ_NEED_INITIAL_FREQ_CHECK that will be marked by platforms which want to go for this check at boot time. Initially this is done for all ARM platforms but others may follow if required. Signed-off-by: Viresh Kumar <viresh.kumar@linaro.org> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
102 lines
2.7 KiB
C
102 lines
2.7 KiB
C
/*
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* Copyright (C) STMicroelectronics 2009
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* Copyright (C) ST-Ericsson SA 2010-2012
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*
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* License Terms: GNU General Public License v2
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* Author: Sundar Iyer <sundar.iyer@stericsson.com>
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* Author: Martin Persson <martin.persson@stericsson.com>
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* Author: Jonas Aaberg <jonas.aberg@stericsson.com>
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/cpufreq.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <linux/platform_device.h>
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#include <linux/clk.h>
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static struct cpufreq_frequency_table *freq_table;
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static struct clk *armss_clk;
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static int dbx500_cpufreq_target(struct cpufreq_policy *policy,
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unsigned int index)
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{
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/* update armss clk frequency */
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return clk_set_rate(armss_clk, freq_table[index].frequency * 1000);
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}
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static unsigned int dbx500_cpufreq_getspeed(unsigned int cpu)
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{
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int i = 0;
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unsigned long freq = clk_get_rate(armss_clk) / 1000;
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/* The value is rounded to closest frequency in the defined table. */
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while (freq_table[i + 1].frequency != CPUFREQ_TABLE_END) {
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if (freq < freq_table[i].frequency +
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(freq_table[i + 1].frequency - freq_table[i].frequency) / 2)
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return freq_table[i].frequency;
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i++;
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}
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return freq_table[i].frequency;
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}
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static int dbx500_cpufreq_init(struct cpufreq_policy *policy)
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{
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return cpufreq_generic_init(policy, freq_table, 20 * 1000);
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}
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static struct cpufreq_driver dbx500_cpufreq_driver = {
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.flags = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS |
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CPUFREQ_NEED_INITIAL_FREQ_CHECK,
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.verify = cpufreq_generic_frequency_table_verify,
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.target_index = dbx500_cpufreq_target,
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.get = dbx500_cpufreq_getspeed,
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.init = dbx500_cpufreq_init,
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.name = "DBX500",
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.attr = cpufreq_generic_attr,
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};
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static int dbx500_cpufreq_probe(struct platform_device *pdev)
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{
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int i = 0;
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freq_table = dev_get_platdata(&pdev->dev);
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if (!freq_table) {
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pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
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return -ENODEV;
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}
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armss_clk = clk_get(&pdev->dev, "armss");
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if (IS_ERR(armss_clk)) {
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pr_err("dbx500-cpufreq: Failed to get armss clk\n");
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return PTR_ERR(armss_clk);
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}
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pr_info("dbx500-cpufreq: Available frequencies:\n");
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while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
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pr_info(" %d Mhz\n", freq_table[i].frequency/1000);
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i++;
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}
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return cpufreq_register_driver(&dbx500_cpufreq_driver);
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}
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static struct platform_driver dbx500_cpufreq_plat_driver = {
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.driver = {
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.name = "cpufreq-ux500",
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.owner = THIS_MODULE,
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},
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.probe = dbx500_cpufreq_probe,
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};
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static int __init dbx500_cpufreq_register(void)
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{
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return platform_driver_register(&dbx500_cpufreq_plat_driver);
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}
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device_initcall(dbx500_cpufreq_register);
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MODULE_LICENSE("GPL v2");
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MODULE_DESCRIPTION("cpufreq driver for DBX500");
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