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 */
34 static 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 
50 static 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 
68 static 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 		of_node_put(cpu);
90 		return -EINVAL;
91 	}
92 
93 	max_freqp = of_get_property(cpu, "clock-frequency", NULL);
94 
95 	of_node_put(cpu);
96 
97 	if (!max_freqp)
98 		return -EINVAL;
99 
100 	/* we need the freq in kHz */
101 	max_freq = *max_freqp / 1000;
102 
103 	pr_debug("max clock-frequency is at %u kHz\n", max_freq);
104 	pr_debug("initializing frequency table\n");
105 
106 	/* initialize frequency table */
107 	cpufreq_for_each_entry(pos, cbe_freqs) {
108 		pos->frequency = max_freq / pos->driver_data;
109 		pr_debug("%d: %d\n", (int)(pos - cbe_freqs), pos->frequency);
110 	}
111 
112 	/* if DEBUG is enabled set_pmode() measures the latency
113 	 * of a transition */
114 	policy->cpuinfo.transition_latency = 25000;
115 
116 	cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
117 	pr_debug("current pmode is at %d\n",cur_pmode);
118 
119 	policy->cur = cbe_freqs[cur_pmode].frequency;
120 
121 #ifdef CONFIG_SMP
122 	cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
123 #endif
124 
125 	policy->freq_table = cbe_freqs;
126 	return 0;
127 }
128 
129 static 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 
141 static 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 
153 static 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 
161 static void __exit cbe_cpufreq_exit(void)
162 {
163 	cpufreq_unregister_driver(&cbe_cpufreq_driver);
164 }
165 
166 module_init(cbe_cpufreq_init);
167 module_exit(cbe_cpufreq_exit);
168 
169 MODULE_LICENSE("GPL");
170 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
171