cpufreq: OMAP: deny initialization if no mpudev
[linux-2.6.git] / drivers / cpufreq / omap-cpufreq.c
1 /*
2  *  CPU frequency scaling for OMAP
3  *
4  *  Copyright (C) 2005 Nokia Corporation
5  *  Written by Tony Lindgren <tony@atomide.com>
6  *
7  *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
8  *
9  * Copyright (C) 2007-2011 Texas Instruments, Inc.
10  * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar
11  *
12  * This program is free software; you can redistribute it and/or modify
13  * it under the terms of the GNU General Public License version 2 as
14  * published by the Free Software Foundation.
15  */
16 #include <linux/types.h>
17 #include <linux/kernel.h>
18 #include <linux/sched.h>
19 #include <linux/cpufreq.h>
20 #include <linux/delay.h>
21 #include <linux/init.h>
22 #include <linux/err.h>
23 #include <linux/clk.h>
24 #include <linux/io.h>
25 #include <linux/opp.h>
26 #include <linux/cpu.h>
27
28 #include <asm/system.h>
29 #include <asm/smp_plat.h>
30 #include <asm/cpu.h>
31
32 #include <plat/clock.h>
33 #include <plat/omap-pm.h>
34 #include <plat/common.h>
35
36 #include <mach/hardware.h>
37
38 #define VERY_HI_RATE    900000000
39
40 #ifdef CONFIG_SMP
41 struct lpj_info {
42         unsigned long   ref;
43         unsigned int    freq;
44 };
45
46 static DEFINE_PER_CPU(struct lpj_info, lpj_ref);
47 static struct lpj_info global_lpj_ref;
48 #endif
49
50 static struct cpufreq_frequency_table *freq_table;
51 static struct clk *mpu_clk;
52 static char *mpu_clk_name;
53 static struct device *mpu_dev;
54
55 static int omap_verify_speed(struct cpufreq_policy *policy)
56 {
57         if (freq_table)
58                 return cpufreq_frequency_table_verify(policy, freq_table);
59
60         if (policy->cpu)
61                 return -EINVAL;
62
63         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
64                                      policy->cpuinfo.max_freq);
65
66         policy->min = clk_round_rate(mpu_clk, policy->min * 1000) / 1000;
67         policy->max = clk_round_rate(mpu_clk, policy->max * 1000) / 1000;
68         cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
69                                      policy->cpuinfo.max_freq);
70         return 0;
71 }
72
73 static unsigned int omap_getspeed(unsigned int cpu)
74 {
75         unsigned long rate;
76
77         if (cpu >= NR_CPUS)
78                 return 0;
79
80         rate = clk_get_rate(mpu_clk) / 1000;
81         return rate;
82 }
83
84 static int omap_target(struct cpufreq_policy *policy,
85                        unsigned int target_freq,
86                        unsigned int relation)
87 {
88         int i, ret = 0;
89         struct cpufreq_freqs freqs;
90
91         /* Ensure desired rate is within allowed range.  Some govenors
92          * (ondemand) will just pass target_freq=0 to get the minimum. */
93         if (target_freq < policy->min)
94                 target_freq = policy->min;
95         if (target_freq > policy->max)
96                 target_freq = policy->max;
97
98         freqs.old = omap_getspeed(policy->cpu);
99         freqs.new = clk_round_rate(mpu_clk, target_freq * 1000) / 1000;
100         freqs.cpu = policy->cpu;
101
102         if (freqs.old == freqs.new && policy->cur == freqs.new)
103                 return ret;
104
105         /* notifiers */
106         for_each_cpu(i, policy->cpus) {
107                 freqs.cpu = i;
108                 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
109         }
110
111 #ifdef CONFIG_CPU_FREQ_DEBUG
112         pr_info("cpufreq-omap: transition: %u --> %u\n", freqs.old, freqs.new);
113 #endif
114
115         ret = clk_set_rate(mpu_clk, freqs.new * 1000);
116         freqs.new = omap_getspeed(policy->cpu);
117
118 #ifdef CONFIG_SMP
119         /*
120          * Note that loops_per_jiffy is not updated on SMP systems in
121          * cpufreq driver. So, update the per-CPU loops_per_jiffy value
122          * on frequency transition. We need to update all dependent CPUs.
123          */
124         for_each_cpu(i, policy->cpus) {
125                 struct lpj_info *lpj = &per_cpu(lpj_ref, i);
126                 if (!lpj->freq) {
127                         lpj->ref = per_cpu(cpu_data, i).loops_per_jiffy;
128                         lpj->freq = freqs.old;
129                 }
130
131                 per_cpu(cpu_data, i).loops_per_jiffy =
132                         cpufreq_scale(lpj->ref, lpj->freq, freqs.new);
133         }
134
135         /* And don't forget to adjust the global one */
136         if (!global_lpj_ref.freq) {
137                 global_lpj_ref.ref = loops_per_jiffy;
138                 global_lpj_ref.freq = freqs.old;
139         }
140         loops_per_jiffy = cpufreq_scale(global_lpj_ref.ref, global_lpj_ref.freq,
141                                         freqs.new);
142 #endif
143
144         /* notifiers */
145         for_each_cpu(i, policy->cpus) {
146                 freqs.cpu = i;
147                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
148         }
149
150         return ret;
151 }
152
153 static int __cpuinit omap_cpu_init(struct cpufreq_policy *policy)
154 {
155         int result = 0;
156
157         mpu_clk = clk_get(NULL, mpu_clk_name);
158         if (IS_ERR(mpu_clk))
159                 return PTR_ERR(mpu_clk);
160
161         if (policy->cpu >= NR_CPUS)
162                 return -EINVAL;
163
164         policy->cur = policy->min = policy->max = omap_getspeed(policy->cpu);
165         opp_init_cpufreq_table(mpu_dev, &freq_table);
166
167         if (freq_table) {
168                 result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
169                 if (!result)
170                         cpufreq_frequency_table_get_attr(freq_table,
171                                                         policy->cpu);
172         } else {
173                 policy->cpuinfo.min_freq = clk_round_rate(mpu_clk, 0) / 1000;
174                 policy->cpuinfo.max_freq = clk_round_rate(mpu_clk,
175                                                         VERY_HI_RATE) / 1000;
176         }
177
178         policy->min = policy->cpuinfo.min_freq;
179         policy->max = policy->cpuinfo.max_freq;
180         policy->cur = omap_getspeed(policy->cpu);
181
182         /*
183          * On OMAP SMP configuartion, both processors share the voltage
184          * and clock. So both CPUs needs to be scaled together and hence
185          * needs software co-ordination. Use cpufreq affected_cpus
186          * interface to handle this scenario. Additional is_smp() check
187          * is to keep SMP_ON_UP build working.
188          */
189         if (is_smp()) {
190                 policy->shared_type = CPUFREQ_SHARED_TYPE_ANY;
191                 cpumask_setall(policy->cpus);
192         }
193
194         /* FIXME: what's the actual transition time? */
195         policy->cpuinfo.transition_latency = 300 * 1000;
196
197         return 0;
198 }
199
200 static int omap_cpu_exit(struct cpufreq_policy *policy)
201 {
202         clk_exit_cpufreq_table(&freq_table);
203         clk_put(mpu_clk);
204         return 0;
205 }
206
207 static struct freq_attr *omap_cpufreq_attr[] = {
208         &cpufreq_freq_attr_scaling_available_freqs,
209         NULL,
210 };
211
212 static struct cpufreq_driver omap_driver = {
213         .flags          = CPUFREQ_STICKY,
214         .verify         = omap_verify_speed,
215         .target         = omap_target,
216         .get            = omap_getspeed,
217         .init           = omap_cpu_init,
218         .exit           = omap_cpu_exit,
219         .name           = "omap",
220         .attr           = omap_cpufreq_attr,
221 };
222
223 static int __init omap_cpufreq_init(void)
224 {
225         if (cpu_is_omap24xx())
226                 mpu_clk_name = "virt_prcm_set";
227         else if (cpu_is_omap34xx())
228                 mpu_clk_name = "dpll1_ck";
229         else if (cpu_is_omap44xx())
230                 mpu_clk_name = "dpll_mpu_ck";
231
232         if (!mpu_clk_name) {
233                 pr_err("%s: unsupported Silicon?\n", __func__);
234                 return -EINVAL;
235         }
236
237         mpu_dev = omap2_get_mpuss_device();
238         if (!mpu_dev) {
239                 pr_warning("%s: unable to get the mpu device\n", __func__);
240                 return -EINVAL;
241         }
242
243         return cpufreq_register_driver(&omap_driver);
244 }
245
246 static void __exit omap_cpufreq_exit(void)
247 {
248         cpufreq_unregister_driver(&omap_driver);
249 }
250
251 MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs");
252 MODULE_LICENSE("GPL");
253 module_init(omap_cpufreq_init);
254 module_exit(omap_cpufreq_exit);