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 	const u32 *max_freqp;
71 	u32 max_freq;
72 	int i, cur_pmode;
73 	struct device_node *cpu;
74 
75 	cpu = of_get_cpu_node(policy->cpu, NULL);
76 
77 	if (!cpu)
78 		return -ENODEV;
79 
80 	pr_debug("init cpufreq on CPU %d\n", policy->cpu);
81 
82 	/*
83 	 * Let's check we can actually get to the CELL regs
84 	 */
85 	if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
86 	    !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
87 		pr_info("invalid CBE regs pointers for cpufreq\n");
88 		return -EINVAL;
89 	}
90 
91 	max_freqp = of_get_property(cpu, "clock-frequency", NULL);
92 
93 	of_node_put(cpu);
94 
95 	if (!max_freqp)
96 		return -EINVAL;
97 
98 	/* we need the freq in kHz */
99 	max_freq = *max_freqp / 1000;
100 
101 	pr_debug("max clock-frequency is at %u kHz\n", max_freq);
102 	pr_debug("initializing frequency table\n");
103 
104 	/* initialize frequency table */
105 	for (i=0; cbe_freqs[i].frequency!=CPUFREQ_TABLE_END; i++) {
106 		cbe_freqs[i].frequency = max_freq / cbe_freqs[i].driver_data;
107 		pr_debug("%d: %d\n", i, cbe_freqs[i].frequency);
108 	}
109 
110 	/* if DEBUG is enabled set_pmode() measures the latency
111 	 * of a transition */
112 	policy->cpuinfo.transition_latency = 25000;
113 
114 	cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
115 	pr_debug("current pmode is at %d\n",cur_pmode);
116 
117 	policy->cur = cbe_freqs[cur_pmode].frequency;
118 
119 #ifdef CONFIG_SMP
120 	cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
121 #endif
122 
123 	/* this ensures that policy->cpuinfo_min
124 	 * and policy->cpuinfo_max are set correctly */
125 	return cpufreq_table_validate_and_show(policy, cbe_freqs);
126 }
127 
128 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
129 			      unsigned int cbe_pmode_new)
130 {
131 	pr_debug("setting frequency for cpu %d to %d kHz, " \
132 		 "1/%d of max frequency\n",
133 		 policy->cpu,
134 		 cbe_freqs[cbe_pmode_new].frequency,
135 		 cbe_freqs[cbe_pmode_new].driver_data);
136 
137 	return set_pmode(policy->cpu, cbe_pmode_new);
138 }
139 
140 static struct cpufreq_driver cbe_cpufreq_driver = {
141 	.verify		= cpufreq_generic_frequency_table_verify,
142 	.target_index	= cbe_cpufreq_target,
143 	.init		= cbe_cpufreq_cpu_init,
144 	.name		= "cbe-cpufreq",
145 	.flags		= CPUFREQ_CONST_LOOPS,
146 };
147 
148 /*
149  * module init and destoy
150  */
151 
152 static int __init cbe_cpufreq_init(void)
153 {
154 	if (!machine_is(cell))
155 		return -ENODEV;
156 
157 	return cpufreq_register_driver(&cbe_cpufreq_driver);
158 }
159 
160 static void __exit cbe_cpufreq_exit(void)
161 {
162 	cpufreq_unregister_driver(&cbe_cpufreq_driver);
163 }
164 
165 module_init(cbe_cpufreq_init);
166 module_exit(cbe_cpufreq_exit);
167 
168 MODULE_LICENSE("GPL");
169 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
170