summaryrefslogtreecommitdiffstats
path: root/drivers/cpufreq/cpufreq-cpu0.c
blob: 4e5b7fb8927cb5304e3baf37dc3ccb87e71c31b9 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
/*
 * Copyright (C) 2012 Freescale Semiconductor, Inc.
 *
 * The OPP code in function cpu0_set_target() is reused from
 * drivers/cpufreq/omap-cpufreq.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#define pr_fmt(fmt)	KBUILD_MODNAME ": " fmt

#include <linux/clk.h>
#include <linux/cpufreq.h>
#include <linux/err.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/opp.h>
#include <linux/platform_device.h>
#include <linux/regulator/consumer.h>
#include <linux/slab.h>

static unsigned int transition_latency;
static unsigned int voltage_tolerance; /* in percentage */

static struct device *cpu_dev;
static struct clk *cpu_clk;
static struct regulator *cpu_reg;
static struct cpufreq_frequency_table *freq_table;

static int cpu0_verify_speed(struct cpufreq_policy *policy)
{
	return cpufreq_frequency_table_verify(policy, freq_table);
}

static unsigned int cpu0_get_speed(unsigned int cpu)
{
	return clk_get_rate(cpu_clk) / 1000;
}

static int cpu0_set_target(struct cpufreq_policy *policy,
			   unsigned int target_freq, unsigned int relation)
{
	struct cpufreq_freqs freqs;
	struct opp *opp;
	unsigned long freq_Hz, volt = 0, volt_old = 0, tol = 0;
	unsigned int index, cpu;
	int ret;

	ret = cpufreq_frequency_table_target(policy, freq_table, target_freq,
					     relation, &index);
	if (ret) {
		pr_err("failed to match target freqency %d: %d\n",
		       target_freq, ret);
		return ret;
	}

	freq_Hz = clk_round_rate(cpu_clk, freq_table[index].frequency * 1000);
	if (freq_Hz < 0)
		freq_Hz = freq_table[index].frequency * 1000;
	freqs.new = freq_Hz / 1000;
	freqs.old = clk_get_rate(cpu_clk) / 1000;

	if (freqs.old == freqs.new)
		return 0;

	for_each_online_cpu(cpu) {
		freqs.cpu = cpu;
		cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
	}

	if (cpu_reg) {
		rcu_read_lock();
		opp = opp_find_freq_ceil(cpu_dev, &freq_Hz);
		if (IS_ERR(opp)) {
			rcu_read_unlock();
			pr_err("failed to find OPP for %ld\n", freq_Hz);
			return PTR_ERR(opp);
		}
		volt = opp_get_voltage(opp);
		rcu_read_unlock();
		tol = volt * voltage_tolerance / 100;
		volt_old = regulator_get_voltage(cpu_reg);
	}

	pr_debug("%u MHz, %ld mV --> %u MHz, %ld mV\n",
		 freqs.old / 1000, volt_old ? volt_old / 1000 : -1,
		 freqs.new / 1000, volt ? volt / 1000 : -1);

	/* scaling up?  scale voltage before frequency */
	if (cpu_reg && freqs.new > freqs.old) {
		ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
		if (ret) {
			pr_err("failed to scale voltage up: %d\n", ret);
			freqs.new = freqs.old;
			return ret;
		}
	}

	ret = clk_set_rate(cpu_clk, freqs.new * 1000);
	if (ret) {
		pr_err("failed to set clock rate: %d\n", ret);
		if (cpu_reg)
			regulator_set_voltage_tol(cpu_reg, volt_old, tol);
		return ret;
	}

	/* scaling down?  scale voltage after frequency */
	if (cpu_reg && freqs.new < freqs.old) {
		ret = regulator_set_voltage_tol(cpu_reg, volt, tol);
		if (ret) {
			pr_err("failed to scale voltage down: %d\n", ret);
			clk_set_rate(cpu_clk, freqs.old * 1000);
			freqs.new = freqs.old;
			return ret;
		}
	}

	for_each_online_cpu(cpu) {
		freqs.cpu = cpu;
		cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
	}

	return 0;
}

static int cpu0_cpufreq_init(struct cpufreq_policy *policy)
{
	int ret;

	if (policy->cpu != 0)
		return -EINVAL;

	ret = cpufreq_frequency_table_cpuinfo(policy, freq_table);
	if (ret) {
		pr_err("invalid frequency table: %d\n", ret);
		return ret;
	}

	policy->cpuinfo.transition_latency = transition_latency;
	policy->cur = clk_get_rate(cpu_clk) / 1000;

	/*
	 * The driver only supports the SMP configuartion where all processors
	 * share the clock and voltage and clock.  Use cpufreq affected_cpus
	 * interface to have all CPUs scaled together.
	 */
	cpumask_setall(policy->cpus);

	cpufreq_frequency_table_get_attr(freq_table, policy->cpu);

	return 0;
}

static int cpu0_cpufreq_exit(struct cpufreq_policy *policy)
{
	cpufreq_frequency_table_put_attr(policy->cpu);

	return 0;
}

static struct freq_attr *cpu0_cpufreq_attr[] = {
	&cpufreq_freq_attr_scaling_available_freqs,
	NULL,
};

static struct cpufreq_driver cpu0_cpufreq_driver = {
	.flags = CPUFREQ_STICKY,
	.verify = cpu0_verify_speed,
	.target = cpu0_set_target,
	.get = cpu0_get_speed,
	.init = cpu0_cpufreq_init,
	.exit = cpu0_cpufreq_exit,
	.name = "generic_cpu0",
	.attr = cpu0_cpufreq_attr,
};

static int cpu0_cpufreq_probe(struct platform_device *pdev)
{
	struct device_node *np;
	int ret;

	for_each_child_of_node(of_find_node_by_path("/cpus"), np) {
		if (of_get_property(np, "operating-points", NULL))
			break;
	}

	if (!np) {
		pr_err("failed to find cpu0 node\n");
		return -ENOENT;
	}

	cpu_dev = &pdev->dev;
	cpu_dev->of_node = np;

	cpu_clk = devm_clk_get(cpu_dev, NULL);
	if (IS_ERR(cpu_clk)) {
		ret = PTR_ERR(cpu_clk);
		pr_err("failed to get cpu0 clock: %d\n", ret);
		goto out_put_node;
	}

	cpu_reg = devm_regulator_get(cpu_dev, "cpu0");
	if (IS_ERR(cpu_reg)) {
		pr_warn("failed to get cpu0 regulator\n");
		cpu_reg = NULL;
	}

	ret = of_init_opp_table(cpu_dev);
	if (ret) {
		pr_err("failed to init OPP table: %d\n", ret);
		goto out_put_node;
	}

	ret = opp_init_cpufreq_table(cpu_dev, &freq_table);
	if (ret) {
		pr_err("failed to init cpufreq table: %d\n", ret);
		goto out_put_node;
	}

	of_property_read_u32(np, "voltage-tolerance", &voltage_tolerance);

	if (of_property_read_u32(np, "clock-latency", &transition_latency))
		transition_latency = CPUFREQ_ETERNAL;

	if (cpu_reg) {
		struct opp *opp;
		unsigned long min_uV, max_uV;
		int i;

		/*
		 * OPP is maintained in order of increasing frequency, and
		 * freq_table initialised from OPP is therefore sorted in the
		 * same order.
		 */
		for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
			;
		rcu_read_lock();
		opp = opp_find_freq_exact(cpu_dev,
				freq_table[0].frequency * 1000, true);
		min_uV = opp_get_voltage(opp);
		opp = opp_find_freq_exact(cpu_dev,
				freq_table[i-1].frequency * 1000, true);
		max_uV = opp_get_voltage(opp);
		rcu_read_unlock();
		ret = regulator_set_voltage_time(cpu_reg, min_uV, max_uV);
		if (ret > 0)
			transition_latency += ret * 1000;
	}

	ret = cpufreq_register_driver(&cpu0_cpufreq_driver);
	if (ret) {
		pr_err("failed register driver: %d\n", ret);
		goto out_free_table;
	}

	of_node_put(np);
	return 0;

out_free_table:
	opp_free_cpufreq_table(cpu_dev, &freq_table);
out_put_node:
	of_node_put(np);
	return ret;
}

static int cpu0_cpufreq_remove(struct platform_device *pdev)
{
	cpufreq_unregister_driver(&cpu0_cpufreq_driver);
	opp_free_cpufreq_table(cpu_dev, &freq_table);

	return 0;
}

static struct platform_driver cpu0_cpufreq_platdrv = {
	.driver = {
		.name	= "cpufreq-cpu0",
		.owner	= THIS_MODULE,
	},
	.probe		= cpu0_cpufreq_probe,
	.remove		= cpu0_cpufreq_remove,
};
module_platform_driver(cpu0_cpufreq_platdrv);

MODULE_AUTHOR("Shawn Guo <shawn.guo@linaro.org>");
MODULE_DESCRIPTION("Generic CPU0 cpufreq driver");
MODULE_LICENSE("GPL");