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/* the CBE supports an 8 step frequency scaling */
34static struct cpufreq_frequency_table cbe_freqs[] = {
35	{0, 1,	0},
36	{0, 2,	0},
37	{0, 3,	0},
38	{0, 4,	0},
39	{0, 5,	0},
40	{0, 6,	0},
41	{0, 8,	0},
42	{0, 10,	0},
43	{0, 0,	CPUFREQ_TABLE_END},
44};
45
46/*
47 * hardware specific functions
48 */
49
50static int set_pmode(unsigned int cpu, unsigned int slow_mode)
51{
52	int rc;
53
54	if (cbe_cpufreq_has_pmi)
55		rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);
56	else
57		rc = cbe_cpufreq_set_pmode(cpu, slow_mode);
58
59	pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));
60
61	return rc;
62}
63
64/*
65 * cpufreq functions
66 */
67
68static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
69{
70	struct cpufreq_frequency_table *pos;
71	const u32 *max_freqp;
72	u32 max_freq;
73	int 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	cpufreq_for_each_entry(pos, cbe_freqs) {
107		pos->frequency = max_freq / pos->driver_data;
108		pr_debug("%d: %d\n", (int)(pos - cbe_freqs), pos->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	cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
122#endif
123
124	/* this ensures that policy->cpuinfo_min
125	 * and policy->cpuinfo_max are set correctly */
126	return cpufreq_table_validate_and_show(policy, cbe_freqs);
127}
128
129static int cbe_cpufreq_target(struct cpufreq_policy *policy,
130			      unsigned int cbe_pmode_new)
131{
132	pr_debug("setting frequency for cpu %d to %d kHz, " \
133		 "1/%d of max frequency\n",
134		 policy->cpu,
135		 cbe_freqs[cbe_pmode_new].frequency,
136		 cbe_freqs[cbe_pmode_new].driver_data);
137
138	return set_pmode(policy->cpu, cbe_pmode_new);
139}
140
141static struct cpufreq_driver cbe_cpufreq_driver = {
142	.verify		= cpufreq_generic_frequency_table_verify,
143	.target_index	= cbe_cpufreq_target,
144	.init		= cbe_cpufreq_cpu_init,
145	.name		= "cbe-cpufreq",
146	.flags		= CPUFREQ_CONST_LOOPS,
147};
148
149/*
150 * module init and destoy
151 */
152
153static int __init cbe_cpufreq_init(void)
154{
155	if (!machine_is(cell))
156		return -ENODEV;
157
158	return cpufreq_register_driver(&cbe_cpufreq_driver);
159}
160
161static void __exit cbe_cpufreq_exit(void)
162{
163	cpufreq_unregister_driver(&cbe_cpufreq_driver);
164}
165
166module_init(cbe_cpufreq_init);
167module_exit(cbe_cpufreq_exit);
168
169MODULE_LICENSE("GPL");
170MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
171