1 /*
2 * Copyright (C) STMicroelectronics 2009
3 * Copyright (C) ST-Ericsson SA 2010-2012
4 *
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>
9 */
10
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>
18
19 static struct cpufreq_frequency_table *freq_table;
20 static struct clk *armss_clk;
21
22 static struct freq_attr *dbx500_cpufreq_attr[] = {
23 &cpufreq_freq_attr_scaling_available_freqs,
24 NULL,
25 };
26
dbx500_cpufreq_verify_speed(struct cpufreq_policy * policy)27 static int dbx500_cpufreq_verify_speed(struct cpufreq_policy *policy)
28 {
29 return cpufreq_frequency_table_verify(policy, freq_table);
30 }
31
dbx500_cpufreq_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)32 static int dbx500_cpufreq_target(struct cpufreq_policy *policy,
33 unsigned int target_freq,
34 unsigned int relation)
35 {
36 struct cpufreq_freqs freqs;
37 unsigned int idx;
38 int ret;
39
40 /* Lookup the next frequency */
41 if (cpufreq_frequency_table_target(policy, freq_table, target_freq,
42 relation, &idx))
43 return -EINVAL;
44
45 freqs.old = policy->cur;
46 freqs.new = freq_table[idx].frequency;
47
48 if (freqs.old == freqs.new)
49 return 0;
50
51 /* pre-change notification */
52 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
53
54 /* update armss clk frequency */
55 ret = clk_set_rate(armss_clk, freqs.new * 1000);
56
57 if (ret) {
58 pr_err("dbx500-cpufreq: Failed to set armss_clk to %d Hz: error %d\n",
59 freqs.new * 1000, ret);
60 return ret;
61 }
62
63 /* post change notification */
64 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
65
66 return 0;
67 }
68
dbx500_cpufreq_getspeed(unsigned int cpu)69 static unsigned int dbx500_cpufreq_getspeed(unsigned int cpu)
70 {
71 int i = 0;
72 unsigned long freq = clk_get_rate(armss_clk) / 1000;
73
74 /* The value is rounded to closest frequency in the defined table. */
75 while (freq_table[i + 1].frequency != CPUFREQ_TABLE_END) {
76 if (freq < freq_table[i].frequency +
77 (freq_table[i + 1].frequency - freq_table[i].frequency) / 2)
78 return freq_table[i].frequency;
79 i++;
80 }
81
82 return freq_table[i].frequency;
83 }
84
dbx500_cpufreq_init(struct cpufreq_policy * policy)85 static int __cpuinit dbx500_cpufreq_init(struct cpufreq_policy *policy)
86 {
87 int res;
88
89 /* get policy fields based on the table */
90 res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
91 if (!res)
92 cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
93 else {
94 pr_err("dbx500-cpufreq: Failed to read policy table\n");
95 return res;
96 }
97
98 policy->min = policy->cpuinfo.min_freq;
99 policy->max = policy->cpuinfo.max_freq;
100 policy->cur = dbx500_cpufreq_getspeed(policy->cpu);
101 policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
102
103 /*
104 * FIXME : Need to take time measurement across the target()
105 * function with no/some/all drivers in the notification
106 * list.
107 */
108 policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
109
110 /* policy sharing between dual CPUs */
111 cpumask_setall(policy->cpus);
112
113 return 0;
114 }
115
116 static struct cpufreq_driver dbx500_cpufreq_driver = {
117 .flags = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS,
118 .verify = dbx500_cpufreq_verify_speed,
119 .target = dbx500_cpufreq_target,
120 .get = dbx500_cpufreq_getspeed,
121 .init = dbx500_cpufreq_init,
122 .name = "DBX500",
123 .attr = dbx500_cpufreq_attr,
124 };
125
dbx500_cpufreq_probe(struct platform_device * pdev)126 static int dbx500_cpufreq_probe(struct platform_device *pdev)
127 {
128 int i = 0;
129
130 freq_table = dev_get_platdata(&pdev->dev);
131 if (!freq_table) {
132 pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
133 return -ENODEV;
134 }
135
136 armss_clk = clk_get(&pdev->dev, "armss");
137 if (IS_ERR(armss_clk)) {
138 pr_err("dbx500-cpufreq: Failed to get armss clk\n");
139 return PTR_ERR(armss_clk);
140 }
141
142 pr_info("dbx500-cpufreq: Available frequencies:\n");
143 while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
144 pr_info(" %d Mhz\n", freq_table[i].frequency/1000);
145 i++;
146 }
147
148 return cpufreq_register_driver(&dbx500_cpufreq_driver);
149 }
150
151 static struct platform_driver dbx500_cpufreq_plat_driver = {
152 .driver = {
153 .name = "cpufreq-ux500",
154 .owner = THIS_MODULE,
155 },
156 .probe = dbx500_cpufreq_probe,
157 };
158
dbx500_cpufreq_register(void)159 static int __init dbx500_cpufreq_register(void)
160 {
161 return platform_driver_register(&dbx500_cpufreq_plat_driver);
162 }
163 device_initcall(dbx500_cpufreq_register);
164
165 MODULE_LICENSE("GPL v2");
166 MODULE_DESCRIPTION("cpufreq driver for DBX500");
167