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
set_pmode(unsigned int cpu,unsigned int slow_mode)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
cbe_cpufreq_cpu_init(struct cpufreq_policy * policy)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
cbe_cpufreq_cpu_exit(struct cpufreq_policy * policy)116 static void cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
117 {
118 cbe_cpufreq_pmi_policy_exit(policy);
119 }
120
cbe_cpufreq_target(struct cpufreq_policy * policy,unsigned int cbe_pmode_new)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
cbe_cpufreq_init(void)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
cbe_cpufreq_exit(void)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