2 * Copyright (C) STMicroelectronics 2009
3 * Copyright (C) ST-Ericsson SA 2010-2012
5 * License Terms: GNU General Public License v2
6 * Author: Sundar Iyer <sundar.iyer@stericsson.com>
7 * Author: Martin Persson <martin.persson@stericsson.com>
8 * Author: Jonas Aaberg <jonas.aberg@stericsson.com>
11 #include <linux/module.h>
12 #include <linux/kernel.h>
13 #include <linux/cpufreq.h>
14 #include <linux/delay.h>
15 #include <linux/slab.h>
16 #include <linux/platform_device.h>
17 #include <linux/clk.h>
19 static struct cpufreq_frequency_table *freq_table;
20 static struct clk *armss_clk;
22 static int dbx500_cpufreq_target(struct cpufreq_policy *policy,
23 unsigned int target_freq,
24 unsigned int relation)
26 struct cpufreq_freqs freqs;
30 /* Lookup the next frequency */
31 if (cpufreq_frequency_table_target(policy, freq_table, target_freq,
35 freqs.old = policy->cur;
36 freqs.new = freq_table[idx].frequency;
38 if (freqs.old == freqs.new)
41 /* pre-change notification */
42 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
44 /* update armss clk frequency */
45 ret = clk_set_rate(armss_clk, freqs.new * 1000);
48 pr_err("dbx500-cpufreq: Failed to set armss_clk to %d Hz: error %d\n",
49 freqs.new * 1000, ret);
50 freqs.new = freqs.old;
53 /* post change notification */
54 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
59 static unsigned int dbx500_cpufreq_getspeed(unsigned int cpu)
62 unsigned long freq = clk_get_rate(armss_clk) / 1000;
64 /* The value is rounded to closest frequency in the defined table. */
65 while (freq_table[i + 1].frequency != CPUFREQ_TABLE_END) {
66 if (freq < freq_table[i].frequency +
67 (freq_table[i + 1].frequency - freq_table[i].frequency) / 2)
68 return freq_table[i].frequency;
72 return freq_table[i].frequency;
75 static int dbx500_cpufreq_init(struct cpufreq_policy *policy)
79 /* get policy fields based on the table */
80 res = cpufreq_table_validate_and_show(policy, freq_table);
82 pr_err("dbx500-cpufreq: Failed to read policy table\n");
86 policy->min = policy->cpuinfo.min_freq;
87 policy->max = policy->cpuinfo.max_freq;
88 policy->cur = dbx500_cpufreq_getspeed(policy->cpu);
89 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
92 * FIXME : Need to take time measurement across the target()
93 * function with no/some/all drivers in the notification
96 policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
98 /* policy sharing between dual CPUs */
99 cpumask_setall(policy->cpus);
104 static struct cpufreq_driver dbx500_cpufreq_driver = {
105 .flags = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS,
106 .verify = cpufreq_generic_frequency_table_verify,
107 .target = dbx500_cpufreq_target,
108 .get = dbx500_cpufreq_getspeed,
109 .init = dbx500_cpufreq_init,
111 .attr = cpufreq_generic_attr,
114 static int dbx500_cpufreq_probe(struct platform_device *pdev)
118 freq_table = dev_get_platdata(&pdev->dev);
120 pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
124 armss_clk = clk_get(&pdev->dev, "armss");
125 if (IS_ERR(armss_clk)) {
126 pr_err("dbx500-cpufreq: Failed to get armss clk\n");
127 return PTR_ERR(armss_clk);
130 pr_info("dbx500-cpufreq: Available frequencies:\n");
131 while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
132 pr_info(" %d Mhz\n", freq_table[i].frequency/1000);
136 return cpufreq_register_driver(&dbx500_cpufreq_driver);
139 static struct platform_driver dbx500_cpufreq_plat_driver = {
141 .name = "cpufreq-ux500",
142 .owner = THIS_MODULE,
144 .probe = dbx500_cpufreq_probe,
147 static int __init dbx500_cpufreq_register(void)
149 return platform_driver_register(&dbx500_cpufreq_plat_driver);
151 device_initcall(dbx500_cpufreq_register);
153 MODULE_LICENSE("GPL v2");
154 MODULE_DESCRIPTION("cpufreq driver for DBX500");