xref: /linux/drivers/cpufreq/ppc_cbe_cpufreq.c (revision a6021aa24f6417416d93318bbfa022ab229c33c8)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * cpufreq driver for the cell processor
4  *
5  * (C) Copyright IBM Deutschland Entwicklung GmbH 2005-2007
6  *
7  * Author: Christian Krafft <krafft@de.ibm.com>
8  */
9 
10 #include <linux/cpufreq.h>
11 #include <linux/module.h>
12 #include <linux/of.h>
13 
14 #include <asm/machdep.h>
15 #include <asm/cell-regs.h>
16 
17 #include "ppc_cbe_cpufreq.h"
18 
19 /* the CBE supports an 8 step frequency scaling */
20 static struct cpufreq_frequency_table cbe_freqs[] = {
21 	{0, 1,	0},
22 	{0, 2,	0},
23 	{0, 3,	0},
24 	{0, 4,	0},
25 	{0, 5,	0},
26 	{0, 6,	0},
27 	{0, 8,	0},
28 	{0, 10,	0},
29 	{0, 0,	CPUFREQ_TABLE_END},
30 };
31 
32 /*
33  * hardware specific functions
34  */
35 
36 static int set_pmode(unsigned int cpu, unsigned int slow_mode)
37 {
38 	int rc;
39 
40 	if (cbe_cpufreq_has_pmi)
41 		rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);
42 	else
43 		rc = cbe_cpufreq_set_pmode(cpu, slow_mode);
44 
45 	pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));
46 
47 	return rc;
48 }
49 
50 /*
51  * cpufreq functions
52  */
53 
54 static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
55 {
56 	struct cpufreq_frequency_table *pos;
57 	const u32 *max_freqp;
58 	u32 max_freq;
59 	int cur_pmode;
60 	struct device_node *cpu;
61 
62 	cpu = of_get_cpu_node(policy->cpu, NULL);
63 
64 	if (!cpu)
65 		return -ENODEV;
66 
67 	pr_debug("init cpufreq on CPU %d\n", policy->cpu);
68 
69 	/*
70 	 * Let's check we can actually get to the CELL regs
71 	 */
72 	if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
73 	    !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
74 		pr_info("invalid CBE regs pointers for cpufreq\n");
75 		of_node_put(cpu);
76 		return -EINVAL;
77 	}
78 
79 	max_freqp = of_get_property(cpu, "clock-frequency", NULL);
80 
81 	of_node_put(cpu);
82 
83 	if (!max_freqp)
84 		return -EINVAL;
85 
86 	/* we need the freq in kHz */
87 	max_freq = *max_freqp / 1000;
88 
89 	pr_debug("max clock-frequency is at %u kHz\n", max_freq);
90 	pr_debug("initializing frequency table\n");
91 
92 	/* initialize frequency table */
93 	cpufreq_for_each_entry(pos, cbe_freqs) {
94 		pos->frequency = max_freq / pos->driver_data;
95 		pr_debug("%d: %d\n", (int)(pos - cbe_freqs), pos->frequency);
96 	}
97 
98 	/* if DEBUG is enabled set_pmode() measures the latency
99 	 * of a transition */
100 	policy->cpuinfo.transition_latency = 25000;
101 
102 	cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
103 	pr_debug("current pmode is at %d\n",cur_pmode);
104 
105 	policy->cur = cbe_freqs[cur_pmode].frequency;
106 
107 #ifdef CONFIG_SMP
108 	cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
109 #endif
110 
111 	policy->freq_table = cbe_freqs;
112 	cbe_cpufreq_pmi_policy_init(policy);
113 	return 0;
114 }
115 
116 static void cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
117 {
118 	cbe_cpufreq_pmi_policy_exit(policy);
119 }
120 
121 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
122 			      unsigned int cbe_pmode_new)
123 {
124 	pr_debug("setting frequency for cpu %d to %d kHz, " \
125 		 "1/%d of max frequency\n",
126 		 policy->cpu,
127 		 cbe_freqs[cbe_pmode_new].frequency,
128 		 cbe_freqs[cbe_pmode_new].driver_data);
129 
130 	return set_pmode(policy->cpu, cbe_pmode_new);
131 }
132 
133 static struct cpufreq_driver cbe_cpufreq_driver = {
134 	.verify		= cpufreq_generic_frequency_table_verify,
135 	.target_index	= cbe_cpufreq_target,
136 	.init		= cbe_cpufreq_cpu_init,
137 	.exit		= cbe_cpufreq_cpu_exit,
138 	.name		= "cbe-cpufreq",
139 	.flags		= CPUFREQ_CONST_LOOPS,
140 };
141 
142 /*
143  * module init and destoy
144  */
145 
146 static int __init cbe_cpufreq_init(void)
147 {
148 	int ret;
149 
150 	if (!machine_is(cell))
151 		return -ENODEV;
152 
153 	cbe_cpufreq_pmi_init();
154 
155 	ret = cpufreq_register_driver(&cbe_cpufreq_driver);
156 	if (ret)
157 		cbe_cpufreq_pmi_exit();
158 
159 	return ret;
160 }
161 
162 static void __exit cbe_cpufreq_exit(void)
163 {
164 	cpufreq_unregister_driver(&cbe_cpufreq_driver);
165 	cbe_cpufreq_pmi_exit();
166 }
167 
168 module_init(cbe_cpufreq_init);
169 module_exit(cbe_cpufreq_exit);
170 
171 MODULE_DESCRIPTION("cpufreq driver for Cell BE processors");
172 MODULE_LICENSE("GPL");
173 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
174