aboutsummaryrefslogtreecommitdiff
path: root/drivers/cpufreq/sun50i-cpufreq-nvmem.c
blob: 2deed8d8773fa6c3ff37d0ed958dca7803aab6d8 (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
// SPDX-License-Identifier: GPL-2.0
/*
 * Allwinner CPUFreq nvmem based driver
 *
 * The sun50i-cpufreq-nvmem driver reads the efuse value from the SoC to
 * provide the OPP framework with required information.
 *
 * Copyright (C) 2019 Yangtao Li <tiny.windzz@gmail.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/module.h>
#include <linux/nvmem-consumer.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pm_opp.h>
#include <linux/slab.h>

#define MAX_NAME_LEN	7

#define NVMEM_MASK	0x7
#define NVMEM_SHIFT	5

static struct platform_device *cpufreq_dt_pdev, *sun50i_cpufreq_pdev;

/**
 * sun50i_cpufreq_get_efuse() - Determine speed grade from efuse value
 * @versions: Set to the value parsed from efuse
 *
 * Returns 0 if success.
 */
static int sun50i_cpufreq_get_efuse(u32 *versions)
{
	struct nvmem_cell *speedbin_nvmem;
	struct device_node *np;
	struct device *cpu_dev;
	u32 *speedbin, efuse_value;
	size_t len;
	int ret;

	cpu_dev = get_cpu_device(0);
	if (!cpu_dev)
		return -ENODEV;

	np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
	if (!np)
		return -ENOENT;

	ret = of_device_is_compatible(np,
				      "allwinner,sun50i-h6-operating-points");
	if (!ret) {
		of_node_put(np);
		return -ENOENT;
	}

	speedbin_nvmem = of_nvmem_cell_get(np, NULL);
	of_node_put(np);
	if (IS_ERR(speedbin_nvmem)) {
		if (PTR_ERR(speedbin_nvmem) != -EPROBE_DEFER)
			pr_err("Could not get nvmem cell: %ld\n",
			       PTR_ERR(speedbin_nvmem));
		return PTR_ERR(speedbin_nvmem);
	}

	speedbin = nvmem_cell_read(speedbin_nvmem, &len);
	nvmem_cell_put(speedbin_nvmem);
	if (IS_ERR(speedbin))
		return PTR_ERR(speedbin);

	efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;

	/*
	 * We treat unexpected efuse values as if the SoC was from
	 * the slowest bin. Expected efuse values are 1-3, slowest
	 * to fastest.
	 */
	if (efuse_value >= 1 && efuse_value <= 3)
		*versions = efuse_value - 1;
	else
		*versions = 0;

	kfree(speedbin);
	return 0;
};

static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
{
	struct opp_table **opp_tables;
	char name[MAX_NAME_LEN];
	unsigned int cpu;
	u32 speed = 0;
	int ret;

	opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
			     GFP_KERNEL);
	if (!opp_tables)
		return -ENOMEM;

	ret = sun50i_cpufreq_get_efuse(&speed);
	if (ret)
		return ret;

	snprintf(name, MAX_NAME_LEN, "speed%d", speed);

	for_each_possible_cpu(cpu) {
		struct device *cpu_dev = get_cpu_device(cpu);

		if (!cpu_dev) {
			ret = -ENODEV;
			goto free_opp;
		}

		opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
		if (IS_ERR(opp_tables[cpu])) {
			ret = PTR_ERR(opp_tables[cpu]);
			pr_err("Failed to set prop name\n");
			goto free_opp;
		}
	}

	cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
							  NULL, 0);
	if (!IS_ERR(cpufreq_dt_pdev)) {
		platform_set_drvdata(pdev, opp_tables);
		return 0;
	}

	ret = PTR_ERR(cpufreq_dt_pdev);
	pr_err("Failed to register platform device\n");

free_opp:
	for_each_possible_cpu(cpu) {
		if (IS_ERR_OR_NULL(opp_tables[cpu]))
			break;
		dev_pm_opp_put_prop_name(opp_tables[cpu]);
	}
	kfree(opp_tables);

	return ret;
}

static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
{
	struct opp_table **opp_tables = platform_get_drvdata(pdev);
	unsigned int cpu;

	platform_device_unregister(cpufreq_dt_pdev);

	for_each_possible_cpu(cpu)
		dev_pm_opp_put_prop_name(opp_tables[cpu]);

	kfree(opp_tables);

	return 0;
}

static struct platform_driver sun50i_cpufreq_driver = {
	.probe = sun50i_cpufreq_nvmem_probe,
	.remove = sun50i_cpufreq_nvmem_remove,
	.driver = {
		.name = "sun50i-cpufreq-nvmem",
	},
};

static const struct of_device_id sun50i_cpufreq_match_list[] = {
	{ .compatible = "allwinner,sun50i-h6" },
	{}
};
MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);

static const struct of_device_id *sun50i_cpufreq_match_node(void)
{
	const struct of_device_id *match;
	struct device_node *np;

	np = of_find_node_by_path("/");
	match = of_match_node(sun50i_cpufreq_match_list, np);
	of_node_put(np);

	return match;
}

/*
 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
 * all the real activity is done in the probe, which may be defered as well.
 * The init here is only registering the driver and the platform device.
 */
static int __init sun50i_cpufreq_init(void)
{
	const struct of_device_id *match;
	int ret;

	match = sun50i_cpufreq_match_node();
	if (!match)
		return -ENODEV;

	ret = platform_driver_register(&sun50i_cpufreq_driver);
	if (unlikely(ret < 0))
		return ret;

	sun50i_cpufreq_pdev =
		platform_device_register_simple("sun50i-cpufreq-nvmem",
						-1, NULL, 0);
	ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
	if (ret == 0)
		return 0;

	platform_driver_unregister(&sun50i_cpufreq_driver);
	return ret;
}
module_init(sun50i_cpufreq_init);

static void __exit sun50i_cpufreq_exit(void)
{
	platform_device_unregister(sun50i_cpufreq_pdev);
	platform_driver_unregister(&sun50i_cpufreq_driver);
}
module_exit(sun50i_cpufreq_exit);

MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
MODULE_LICENSE("GPL v2");