1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Allwinner CPUFreq nvmem based driver
4 *
5 * The sun50i-cpufreq-nvmem driver reads the efuse value from the SoC to
6 * provide the OPP framework with required information.
7 *
8 * Copyright (C) 2019 Yangtao Li <tiny.windzz@gmail.com>
9 */
10
11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12
13#include <linux/module.h>
14#include <linux/nvmem-consumer.h>
15#include <linux/of_device.h>
16#include <linux/platform_device.h>
17#include <linux/pm_opp.h>
18#include <linux/slab.h>
19
20#define MAX_NAME_LEN	7
21
22#define NVMEM_MASK	0x7
23#define NVMEM_SHIFT	5
24
25static struct platform_device *cpufreq_dt_pdev, *sun50i_cpufreq_pdev;
26
27/**
28 * sun50i_cpufreq_get_efuse() - Determine speed grade from efuse value
29 * @versions: Set to the value parsed from efuse
30 *
31 * Returns 0 if success.
32 */
33static int sun50i_cpufreq_get_efuse(u32 *versions)
34{
35	struct nvmem_cell *speedbin_nvmem;
36	struct device_node *np;
37	struct device *cpu_dev;
38	u32 *speedbin, efuse_value;
39	size_t len;
40	int ret;
41
42	cpu_dev = get_cpu_device(0);
43	if (!cpu_dev)
44		return -ENODEV;
45
46	np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
47	if (!np)
48		return -ENOENT;
49
50	ret = of_device_is_compatible(np,
51				      "allwinner,sun50i-h6-operating-points");
52	if (!ret) {
53		of_node_put(np);
54		return -ENOENT;
55	}
56
57	speedbin_nvmem = of_nvmem_cell_get(np, NULL);
58	of_node_put(np);
59	if (IS_ERR(speedbin_nvmem)) {
60		if (PTR_ERR(speedbin_nvmem) != -EPROBE_DEFER)
61			pr_err("Could not get nvmem cell: %ld\n",
62			       PTR_ERR(speedbin_nvmem));
63		return PTR_ERR(speedbin_nvmem);
64	}
65
66	speedbin = nvmem_cell_read(speedbin_nvmem, &len);
67	nvmem_cell_put(speedbin_nvmem);
68	if (IS_ERR(speedbin))
69		return PTR_ERR(speedbin);
70
71	efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
72
73	/*
74	 * We treat unexpected efuse values as if the SoC was from
75	 * the slowest bin. Expected efuse values are 1-3, slowest
76	 * to fastest.
77	 */
78	if (efuse_value >= 1 && efuse_value <= 3)
79		*versions = efuse_value - 1;
80	else
81		*versions = 0;
82
83	kfree(speedbin);
84	return 0;
85};
86
87static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
88{
89	struct opp_table **opp_tables;
90	char name[MAX_NAME_LEN];
91	unsigned int cpu;
92	u32 speed = 0;
93	int ret;
94
95	opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
96			     GFP_KERNEL);
97	if (!opp_tables)
98		return -ENOMEM;
99
100	ret = sun50i_cpufreq_get_efuse(&speed);
101	if (ret) {
102		kfree(opp_tables);
103		return ret;
104	}
105
106	snprintf(name, MAX_NAME_LEN, "speed%d", speed);
107
108	for_each_possible_cpu(cpu) {
109		struct device *cpu_dev = get_cpu_device(cpu);
110
111		if (!cpu_dev) {
112			ret = -ENODEV;
113			goto free_opp;
114		}
115
116		opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
117		if (IS_ERR(opp_tables[cpu])) {
118			ret = PTR_ERR(opp_tables[cpu]);
119			pr_err("Failed to set prop name\n");
120			goto free_opp;
121		}
122	}
123
124	cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
125							  NULL, 0);
126	if (!IS_ERR(cpufreq_dt_pdev)) {
127		platform_set_drvdata(pdev, opp_tables);
128		return 0;
129	}
130
131	ret = PTR_ERR(cpufreq_dt_pdev);
132	pr_err("Failed to register platform device\n");
133
134free_opp:
135	for_each_possible_cpu(cpu) {
136		if (IS_ERR_OR_NULL(opp_tables[cpu]))
137			break;
138		dev_pm_opp_put_prop_name(opp_tables[cpu]);
139	}
140	kfree(opp_tables);
141
142	return ret;
143}
144
145static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
146{
147	struct opp_table **opp_tables = platform_get_drvdata(pdev);
148	unsigned int cpu;
149
150	platform_device_unregister(cpufreq_dt_pdev);
151
152	for_each_possible_cpu(cpu)
153		dev_pm_opp_put_prop_name(opp_tables[cpu]);
154
155	kfree(opp_tables);
156
157	return 0;
158}
159
160static struct platform_driver sun50i_cpufreq_driver = {
161	.probe = sun50i_cpufreq_nvmem_probe,
162	.remove = sun50i_cpufreq_nvmem_remove,
163	.driver = {
164		.name = "sun50i-cpufreq-nvmem",
165	},
166};
167
168static const struct of_device_id sun50i_cpufreq_match_list[] = {
169	{ .compatible = "allwinner,sun50i-h6" },
170	{}
171};
172MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
173
174static const struct of_device_id *sun50i_cpufreq_match_node(void)
175{
176	const struct of_device_id *match;
177	struct device_node *np;
178
179	np = of_find_node_by_path("/");
180	match = of_match_node(sun50i_cpufreq_match_list, np);
181	of_node_put(np);
182
183	return match;
184}
185
186/*
187 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
188 * all the real activity is done in the probe, which may be defered as well.
189 * The init here is only registering the driver and the platform device.
190 */
191static int __init sun50i_cpufreq_init(void)
192{
193	const struct of_device_id *match;
194	int ret;
195
196	match = sun50i_cpufreq_match_node();
197	if (!match)
198		return -ENODEV;
199
200	ret = platform_driver_register(&sun50i_cpufreq_driver);
201	if (unlikely(ret < 0))
202		return ret;
203
204	sun50i_cpufreq_pdev =
205		platform_device_register_simple("sun50i-cpufreq-nvmem",
206						-1, NULL, 0);
207	ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
208	if (ret == 0)
209		return 0;
210
211	platform_driver_unregister(&sun50i_cpufreq_driver);
212	return ret;
213}
214module_init(sun50i_cpufreq_init);
215
216static void __exit sun50i_cpufreq_exit(void)
217{
218	platform_device_unregister(sun50i_cpufreq_pdev);
219	platform_driver_unregister(&sun50i_cpufreq_driver);
220}
221module_exit(sun50i_cpufreq_exit);
222
223MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
224MODULE_LICENSE("GPL v2");
225