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/module.h>
25 #include <linux/of_platform.h>
26
27 #include <asm/machdep.h>
28 #include <asm/prom.h>
29 #include <asm/cell-regs.h>
30
31 #include "ppc_cbe_cpufreq.h"
32
33 static DEFINE_MUTEX(cbe_switch_mutex);
34
35
36 /* the CBE supports an 8 step frequency scaling */
37 static struct cpufreq_frequency_table cbe_freqs[] = {
38 {1, 0},
39 {2, 0},
40 {3, 0},
41 {4, 0},
42 {5, 0},
43 {6, 0},
44 {8, 0},
45 {10, 0},
46 {0, CPUFREQ_TABLE_END},
47 };
48
49 /*
50 * hardware specific functions
51 */
52
set_pmode(unsigned int cpu,unsigned int slow_mode)53 static int set_pmode(unsigned int cpu, unsigned int slow_mode)
54 {
55 int rc;
56
57 if (cbe_cpufreq_has_pmi)
58 rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);
59 else
60 rc = cbe_cpufreq_set_pmode(cpu, slow_mode);
61
62 pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));
63
64 return rc;
65 }
66
67 /*
68 * cpufreq functions
69 */
70
cbe_cpufreq_cpu_init(struct cpufreq_policy * policy)71 static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
72 {
73 const u32 *max_freqp;
74 u32 max_freq;
75 int i, cur_pmode;
76 struct device_node *cpu;
77
78 cpu = of_get_cpu_node(policy->cpu, NULL);
79
80 if (!cpu)
81 return -ENODEV;
82
83 pr_debug("init cpufreq on CPU %d\n", policy->cpu);
84
85 /*
86 * Let's check we can actually get to the CELL regs
87 */
88 if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
89 !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
90 pr_info("invalid CBE regs pointers for cpufreq\n");
91 return -EINVAL;
92 }
93
94 max_freqp = of_get_property(cpu, "clock-frequency", NULL);
95
96 of_node_put(cpu);
97
98 if (!max_freqp)
99 return -EINVAL;
100
101 /* we need the freq in kHz */
102 max_freq = *max_freqp / 1000;
103
104 pr_debug("max clock-frequency is at %u kHz\n", max_freq);
105 pr_debug("initializing frequency table\n");
106
107 /* initialize frequency table */
108 for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
109 cbe_freqs[i].frequency = max_freq / cbe_freqs[i].index;
110 pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
111 }
112
113 /* if DEBUG is enabled set_pmode() measures the latency
114 * of a transition */
115 policy->cpuinfo.transition_latency = 25000;
116
117 cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
118 pr_debug("current pmode is at %d\n",cur_pmode);
119
120 policy->cur = cbe_freqs[cur_pmode].frequency;
121
122 #ifdef CONFIG_SMP
123 cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
124 #endif
125
126 cpufreq_frequency_table_get_attr(cbe_freqs, policy->cpu);
127
128 /* this ensures that policy->cpuinfo_min
129 * and policy->cpuinfo_max are set correctly */
130 return cpufreq_frequency_table_cpuinfo(policy, cbe_freqs);
131 }
132
cbe_cpufreq_cpu_exit(struct cpufreq_policy * policy)133 static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
134 {
135 cpufreq_frequency_table_put_attr(policy->cpu);
136 return 0;
137 }
138
cbe_cpufreq_verify(struct cpufreq_policy * policy)139 static int cbe_cpufreq_verify(struct cpufreq_policy *policy)
140 {
141 return cpufreq_frequency_table_verify(policy, cbe_freqs);
142 }
143
cbe_cpufreq_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)144 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
145 unsigned int target_freq,
146 unsigned int relation)
147 {
148 int rc;
149 struct cpufreq_freqs freqs;
150 unsigned int cbe_pmode_new;
151
152 cpufreq_frequency_table_target(policy,
153 cbe_freqs,
154 target_freq,
155 relation,
156 &cbe_pmode_new);
157
158 freqs.old = policy->cur;
159 freqs.new = cbe_freqs[cbe_pmode_new].frequency;
160
161 mutex_lock(&cbe_switch_mutex);
162 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
163
164 pr_debug("setting frequency for cpu %d to %d kHz, " \
165 "1/%d of max frequency\n",
166 policy->cpu,
167 cbe_freqs[cbe_pmode_new].frequency,
168 cbe_freqs[cbe_pmode_new].index);
169
170 rc = set_pmode(policy->cpu, cbe_pmode_new);
171
172 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
173 mutex_unlock(&cbe_switch_mutex);
174
175 return rc;
176 }
177
178 static struct cpufreq_driver cbe_cpufreq_driver = {
179 .verify = cbe_cpufreq_verify,
180 .target = cbe_cpufreq_target,
181 .init = cbe_cpufreq_cpu_init,
182 .exit = cbe_cpufreq_cpu_exit,
183 .name = "cbe-cpufreq",
184 .owner = THIS_MODULE,
185 .flags = CPUFREQ_CONST_LOOPS,
186 };
187
188 /*
189 * module init and destoy
190 */
191
cbe_cpufreq_init(void)192 static int __init cbe_cpufreq_init(void)
193 {
194 if (!machine_is(cell))
195 return -ENODEV;
196
197 return cpufreq_register_driver(&cbe_cpufreq_driver);
198 }
199
cbe_cpufreq_exit(void)200 static void __exit cbe_cpufreq_exit(void)
201 {
202 cpufreq_unregister_driver(&cbe_cpufreq_driver);
203 }
204
205 module_init(cbe_cpufreq_init);
206 module_exit(cbe_cpufreq_exit);
207
208 MODULE_LICENSE("GPL");
209 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
210