Merge branch 'kvm-updates/2.6.28' of git://git.kernel.org/pub/scm/linux/kernel/git...
[linux-2.6] / arch / powerpc / platforms / cell / cbe_cpufreq.c
1 /*
2  * cpufreq driver for the cell processor
3  *
4  * (C) Copyright IBM Deutschland Entwicklung GmbH 2005-2007
5  *
6  * Author: Christian Krafft <krafft@de.ibm.com>
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2, or (at your option)
11  * any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21  */
22
23 #include <linux/cpufreq.h>
24 #include <linux/of_platform.h>
25
26 #include <asm/machdep.h>
27 #include <asm/prom.h>
28 #include <asm/cell-regs.h>
29 #include "cbe_cpufreq.h"
30
31 static DEFINE_MUTEX(cbe_switch_mutex);
32
33
34 /* the CBE supports an 8 step frequency scaling */
35 static struct cpufreq_frequency_table cbe_freqs[] = {
36         {1,     0},
37         {2,     0},
38         {3,     0},
39         {4,     0},
40         {5,     0},
41         {6,     0},
42         {8,     0},
43         {10,    0},
44         {0,     CPUFREQ_TABLE_END},
45 };
46
47 /*
48  * hardware specific functions
49  */
50
51 static int set_pmode(unsigned int cpu, unsigned int slow_mode)
52 {
53         int rc;
54
55         if (cbe_cpufreq_has_pmi)
56                 rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);
57         else
58                 rc = cbe_cpufreq_set_pmode(cpu, slow_mode);
59
60         pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));
61
62         return rc;
63 }
64
65 /*
66  * cpufreq functions
67  */
68
69 static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
70 {
71         const u32 *max_freqp;
72         u32 max_freq;
73         int i, cur_pmode;
74         struct device_node *cpu;
75
76         cpu = of_get_cpu_node(policy->cpu, NULL);
77
78         if (!cpu)
79                 return -ENODEV;
80
81         pr_debug("init cpufreq on CPU %d\n", policy->cpu);
82
83         /*
84          * Let's check we can actually get to the CELL regs
85          */
86         if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
87             !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
88                 pr_info("invalid CBE regs pointers for cpufreq\n");
89                 return -EINVAL;
90         }
91
92         max_freqp = of_get_property(cpu, "clock-frequency", NULL);
93
94         of_node_put(cpu);
95
96         if (!max_freqp)
97                 return -EINVAL;
98
99         /* we need the freq in kHz */
100         max_freq = *max_freqp / 1000;
101
102         pr_debug("max clock-frequency is at %u kHz\n", max_freq);
103         pr_debug("initializing frequency table\n");
104
105         /* initialize frequency table */
106         for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
107                 cbe_freqs[i].frequency = max_freq / cbe_freqs[i].index;
108                 pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
109         }
110
111         /* if DEBUG is enabled set_pmode() measures the latency
112          * of a transition */
113         policy->cpuinfo.transition_latency = 25000;
114
115         cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
116         pr_debug("current pmode is at %d\n",cur_pmode);
117
118         policy->cur = cbe_freqs[cur_pmode].frequency;
119
120 #ifdef CONFIG_SMP
121         policy->cpus = per_cpu(cpu_sibling_map, policy->cpu);
122 #endif
123
124         cpufreq_frequency_table_get_attr(cbe_freqs, policy->cpu);
125
126         /* this ensures that policy->cpuinfo_min
127          * and policy->cpuinfo_max are set correctly */
128         return cpufreq_frequency_table_cpuinfo(policy, cbe_freqs);
129 }
130
131 static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
132 {
133         cpufreq_frequency_table_put_attr(policy->cpu);
134         return 0;
135 }
136
137 static int cbe_cpufreq_verify(struct cpufreq_policy *policy)
138 {
139         return cpufreq_frequency_table_verify(policy, cbe_freqs);
140 }
141
142 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
143                               unsigned int target_freq,
144                               unsigned int relation)
145 {
146         int rc;
147         struct cpufreq_freqs freqs;
148         unsigned int cbe_pmode_new;
149
150         cpufreq_frequency_table_target(policy,
151                                        cbe_freqs,
152                                        target_freq,
153                                        relation,
154                                        &cbe_pmode_new);
155
156         freqs.old = policy->cur;
157         freqs.new = cbe_freqs[cbe_pmode_new].frequency;
158         freqs.cpu = policy->cpu;
159
160         mutex_lock(&cbe_switch_mutex);
161         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
162
163         pr_debug("setting frequency for cpu %d to %d kHz, " \
164                  "1/%d of max frequency\n",
165                  policy->cpu,
166                  cbe_freqs[cbe_pmode_new].frequency,
167                  cbe_freqs[cbe_pmode_new].index);
168
169         rc = set_pmode(policy->cpu, cbe_pmode_new);
170
171         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
172         mutex_unlock(&cbe_switch_mutex);
173
174         return rc;
175 }
176
177 static struct cpufreq_driver cbe_cpufreq_driver = {
178         .verify         = cbe_cpufreq_verify,
179         .target         = cbe_cpufreq_target,
180         .init           = cbe_cpufreq_cpu_init,
181         .exit           = cbe_cpufreq_cpu_exit,
182         .name           = "cbe-cpufreq",
183         .owner          = THIS_MODULE,
184         .flags          = CPUFREQ_CONST_LOOPS,
185 };
186
187 /*
188  * module init and destoy
189  */
190
191 static int __init cbe_cpufreq_init(void)
192 {
193         if (!machine_is(cell))
194                 return -ENODEV;
195
196         return cpufreq_register_driver(&cbe_cpufreq_driver);
197 }
198
199 static void __exit cbe_cpufreq_exit(void)
200 {
201         cpufreq_unregister_driver(&cbe_cpufreq_driver);
202 }
203
204 module_init(cbe_cpufreq_init);
205 module_exit(cbe_cpufreq_exit);
206
207 MODULE_LICENSE("GPL");
208 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");