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 void cbe_cpufreq_cpu_exit(struct cpufreq_policy *policy)
117{
118	cbe_cpufreq_pmi_policy_exit(policy);
119}
120
121static 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
133static 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
146static 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
162static void __exit cbe_cpufreq_exit(void)
163{
164	cpufreq_unregister_driver(&cbe_cpufreq_driver);
165	cbe_cpufreq_pmi_exit();
166}
167
168module_init(cbe_cpufreq_init);
169module_exit(cbe_cpufreq_exit);
170
171MODULE_DESCRIPTION("cpufreq driver for Cell BE processors");
172MODULE_LICENSE("GPL");
173MODULE_AUTHOR("Christian Krafft <krafft@de.ibm.com>");