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_platform.h>
13
14 #include <asm/machdep.h>
15 #include <asm/prom.h>
16 #include <asm/cell-regs.h>
17
18 #include "ppc_cbe_cpufreq.h"
19
20 /* the CBE supports an 8 step frequency scaling */
21 static struct cpufreq_frequency_table cbe_freqs[] = {
22 {0, 1, 0},
23 {0, 2, 0},
24 {0, 3, 0},
25 {0, 4, 0},
26 {0, 5, 0},
27 {0, 6, 0},
28 {0, 8, 0},
29 {0, 10, 0},
30 {0, 0, CPUFREQ_TABLE_END},
31 };
32
33 /*
34 * hardware specific functions
35 */
36
set_pmode(unsigned int cpu,unsigned int slow_mode)37 static int set_pmode(unsigned int cpu, unsigned int slow_mode)
38 {
39 int rc;
40
41 if (cbe_cpufreq_has_pmi)
42 rc = cbe_cpufreq_set_pmode_pmi(cpu, slow_mode);
43 else
44 rc = cbe_cpufreq_set_pmode(cpu, slow_mode);
45
46 pr_debug("register contains slow mode %d\n", cbe_cpufreq_get_pmode(cpu));
47
48 return rc;
49 }
50
51 /*
52 * cpufreq functions
53 */
54
cbe_cpufreq_cpu_init(struct cpufreq_policy * policy)55 static int cbe_cpufreq_cpu_init(struct cpufreq_policy *policy)
56 {
57 struct cpufreq_frequency_table *pos;
58 const u32 *max_freqp;
59 u32 max_freq;
60 int cur_pmode;
61 struct device_node *cpu;
62
63 cpu = of_get_cpu_node(policy->cpu, NULL);
64
65 if (!cpu)
66 return -ENODEV;
67
68 pr_debug("init cpufreq on CPU %d\n", policy->cpu);
69
70 /*
71 * Let's check we can actually get to the CELL regs
72 */
73 if (!cbe_get_cpu_pmd_regs(policy->cpu) ||
74 !cbe_get_cpu_mic_tm_regs(policy->cpu)) {
75 pr_info("invalid CBE regs pointers for cpufreq\n");
76 of_node_put(cpu);
77 return -EINVAL;
78 }
79
80 max_freqp = of_get_property(cpu, "clock-frequency", NULL);
81
82 of_node_put(cpu);
83
84 if (!max_freqp)
85 return -EINVAL;
86
87 /* we need the freq in kHz */
88 max_freq = *max_freqp / 1000;
89
90 pr_debug("max clock-frequency is at %u kHz\n", max_freq);
91 pr_debug("initializing frequency table\n");
92
93 /* initialize frequency table */
94 cpufreq_for_each_entry(pos, cbe_freqs) {
95 pos->frequency = max_freq / pos->driver_data;
96 pr_debug("%d: %d\n", (int)(pos - cbe_freqs), pos->frequency);
97 }
98
99 /* if DEBUG is enabled set_pmode() measures the latency
100 * of a transition */
101 policy->cpuinfo.transition_latency = 25000;
102
103 cur_pmode = cbe_cpufreq_get_pmode(policy->cpu);
104 pr_debug("current pmode is at %d\n",cur_pmode);
105
106 policy->cur = cbe_freqs[cur_pmode].frequency;
107
108 #ifdef CONFIG_SMP
109 cpumask_copy(policy->cpus, cpu_sibling_mask(policy->cpu));
110 #endif
111
112 policy->freq_table = cbe_freqs;
113 cbe_cpufreq_pmi_policy_init(policy);
114 return 0;
115 }
116
cbe_cpufreq_cpu_exit(struct cpufreq_policy * policy)117 static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
118 {
119 cbe_cpufreq_pmi_policy_exit(policy);
120 return 0;
121 }
122
cbe_cpufreq_target(struct cpufreq_policy * policy,unsigned int cbe_pmode_new)123 static int cbe_cpufreq_target(struct cpufreq_policy *policy,
124 unsigned int cbe_pmode_new)
125 {
126 pr_debug("setting frequency for cpu %d to %d kHz, " \
127 "1/%d of max frequency\n",
128 policy->cpu,
129 cbe_freqs[cbe_pmode_new].frequency,
130 cbe_freqs[cbe_pmode_new].driver_data);
131
132 return set_pmode(policy->cpu, cbe_pmode_new);
133 }
134
135 static struct cpufreq_driver cbe_cpufreq_driver = {
136 .verify = cpufreq_generic_frequency_table_verify,
137 .target_index = cbe_cpufreq_target,
138 .init = cbe_cpufreq_cpu_init,
139 .exit = cbe_cpufreq_cpu_exit,
140 .name = "cbe-cpufreq",
141 .flags = CPUFREQ_CONST_LOOPS,
142 };
143
144 /*
145 * module init and destoy
146 */
147
cbe_cpufreq_init(void)148 static int __init cbe_cpufreq_init(void)
149 {
150 int ret;
151
152 if (!machine_is(cell))
153 return -ENODEV;
154
155 cbe_cpufreq_pmi_init();
156
157 ret = cpufreq_register_driver(&cbe_cpufreq_driver);
158 if (ret)
159 cbe_cpufreq_pmi_exit();
160
161 return ret;
162 }
163
cbe_cpufreq_exit(void)164 static void __exit cbe_cpufreq_exit(void)
165 {
166 cpufreq_unregister_driver(&cbe_cpufreq_driver);
167 cbe_cpufreq_pmi_exit();
168 }
169
170 module_init(cbe_cpufreq_init);
171 module_exit(cbe_cpufreq_exit);
172
173 MODULE_LICENSE("GPL");
174 MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
175