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 */
20static 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
36static 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
54static 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
116static int cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
117{
118	cbe_cpufreq_pmi_policy_exit(policy);
119	return 0;
120}
121
122static int cbe_cpufreq_target(struct cpufreq_policy *policy,
123			      unsigned int cbe_pmode_new)
124{
125	pr_debug("setting frequency for cpu %d to %d kHz, " \
126		 "1/%d of max frequency\n",
127		 policy->cpu,
128		 cbe_freqs[cbe_pmode_new].frequency,
129		 cbe_freqs[cbe_pmode_new].driver_data);
130
131	return set_pmode(policy->cpu, cbe_pmode_new);
132}
133
134static struct cpufreq_driver cbe_cpufreq_driver = {
135	.verify		= cpufreq_generic_frequency_table_verify,
136	.target_index	= cbe_cpufreq_target,
137	.init		= cbe_cpufreq_cpu_init,
138	.exit		= cbe_cpufreq_cpu_exit,
139	.name		= "cbe-cpufreq",
140	.flags		= CPUFREQ_CONST_LOOPS,
141};
142
143/*
144 * module init and destoy
145 */
146
147static int __init cbe_cpufreq_init(void)
148{
149	int ret;
150
151	if (!machine_is(cell))
152		return -ENODEV;
153
154	cbe_cpufreq_pmi_init();
155
156	ret = cpufreq_register_driver(&cbe_cpufreq_driver);
157	if (ret)
158		cbe_cpufreq_pmi_exit();
159
160	return ret;
161}
162
163static void __exit cbe_cpufreq_exit(void)
164{
165	cpufreq_unregister_driver(&cbe_cpufreq_driver);
166	cbe_cpufreq_pmi_exit();
167}
168
169module_init(cbe_cpufreq_init);
170module_exit(cbe_cpufreq_exit);
171
172MODULE_LICENSE("GPL");
173MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");
174