xref: /linux/drivers/cpufreq/sun50i-cpufreq-nvmem.c (revision a6021aa24f6417416d93318bbfa022ab229c33c8)
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/arm-smccc.h>
14 #include <linux/cpu.h>
15 #include <linux/module.h>
16 #include <linux/nvmem-consumer.h>
17 #include <linux/of.h>
18 #include <linux/platform_device.h>
19 #include <linux/pm_opp.h>
20 #include <linux/slab.h>
21 
22 #define NVMEM_MASK	0x7
23 #define NVMEM_SHIFT	5
24 
25 static struct platform_device *cpufreq_dt_pdev, *sun50i_cpufreq_pdev;
26 
27 struct sunxi_cpufreq_data {
28 	u32 (*efuse_xlate)(u32 speedbin);
29 };
30 
31 static u32 sun50i_h6_efuse_xlate(u32 speedbin)
32 {
33 	u32 efuse_value;
34 
35 	efuse_value = (speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
36 
37 	/*
38 	 * We treat unexpected efuse values as if the SoC was from
39 	 * the slowest bin. Expected efuse values are 1-3, slowest
40 	 * to fastest.
41 	 */
42 	if (efuse_value >= 1 && efuse_value <= 3)
43 		return efuse_value - 1;
44 	else
45 		return 0;
46 }
47 
48 static int get_soc_id_revision(void)
49 {
50 #ifdef CONFIG_HAVE_ARM_SMCCC_DISCOVERY
51 	return arm_smccc_get_soc_id_revision();
52 #else
53 	return SMCCC_RET_NOT_SUPPORTED;
54 #endif
55 }
56 
57 /*
58  * Judging by the OPP tables in the vendor BSP, the quality order of the
59  * returned speedbin index is 4 -> 0/2 -> 3 -> 1, from worst to best.
60  * 0 and 2 seem identical from the OPP tables' point of view.
61  */
62 static u32 sun50i_h616_efuse_xlate(u32 speedbin)
63 {
64 	int ver_bits = get_soc_id_revision();
65 	u32 value = 0;
66 
67 	switch (speedbin & 0xffff) {
68 	case 0x2000:
69 		value = 0;
70 		break;
71 	case 0x2400:
72 	case 0x7400:
73 	case 0x2c00:
74 	case 0x7c00:
75 		if (ver_bits != SMCCC_RET_NOT_SUPPORTED && ver_bits <= 1) {
76 			/* ic version A/B */
77 			value = 1;
78 		} else {
79 			/* ic version C and later version */
80 			value = 2;
81 		}
82 		break;
83 	case 0x5000:
84 	case 0x5400:
85 	case 0x6000:
86 		value = 3;
87 		break;
88 	case 0x5c00:
89 		value = 4;
90 		break;
91 	case 0x5d00:
92 		value = 0;
93 		break;
94 	case 0x6c00:
95 		value = 5;
96 		break;
97 	default:
98 		pr_warn("sun50i-cpufreq-nvmem: unknown speed bin 0x%x, using default bin 0\n",
99 			speedbin & 0xffff);
100 		value = 0;
101 		break;
102 	}
103 
104 	return value;
105 }
106 
107 static struct sunxi_cpufreq_data sun50i_h6_cpufreq_data = {
108 	.efuse_xlate = sun50i_h6_efuse_xlate,
109 };
110 
111 static struct sunxi_cpufreq_data sun50i_h616_cpufreq_data = {
112 	.efuse_xlate = sun50i_h616_efuse_xlate,
113 };
114 
115 static const struct of_device_id cpu_opp_match_list[] = {
116 	{ .compatible = "allwinner,sun50i-h6-operating-points",
117 	  .data = &sun50i_h6_cpufreq_data,
118 	},
119 	{ .compatible = "allwinner,sun50i-h616-operating-points",
120 	  .data = &sun50i_h616_cpufreq_data,
121 	},
122 	{}
123 };
124 
125 /**
126  * dt_has_supported_hw() - Check if any OPPs use opp-supported-hw
127  *
128  * If we ask the cpufreq framework to use the opp-supported-hw feature, it
129  * will ignore every OPP node without that DT property. If none of the OPPs
130  * have it, the driver will fail probing, due to the lack of OPPs.
131  *
132  * Returns true if we have at least one OPP with the opp-supported-hw property.
133  */
134 static bool dt_has_supported_hw(void)
135 {
136 	bool has_opp_supported_hw = false;
137 	struct device *cpu_dev;
138 
139 	cpu_dev = get_cpu_device(0);
140 	if (!cpu_dev)
141 		return false;
142 
143 	struct device_node *np __free(device_node) =
144 		dev_pm_opp_of_get_opp_desc_node(cpu_dev);
145 	if (!np)
146 		return false;
147 
148 	for_each_child_of_node_scoped(np, opp) {
149 		if (of_property_present(opp, "opp-supported-hw")) {
150 			has_opp_supported_hw = true;
151 			break;
152 		}
153 	}
154 
155 	return has_opp_supported_hw;
156 }
157 
158 /**
159  * sun50i_cpufreq_get_efuse() - Determine speed grade from efuse value
160  *
161  * Returns non-negative speed bin index on success, a negative error
162  * value otherwise.
163  */
164 static int sun50i_cpufreq_get_efuse(void)
165 {
166 	const struct sunxi_cpufreq_data *opp_data;
167 	struct nvmem_cell *speedbin_nvmem;
168 	const struct of_device_id *match;
169 	struct device *cpu_dev;
170 	u32 *speedbin;
171 	int ret;
172 
173 	cpu_dev = get_cpu_device(0);
174 	if (!cpu_dev)
175 		return -ENODEV;
176 
177 	struct device_node *np __free(device_node) =
178 		dev_pm_opp_of_get_opp_desc_node(cpu_dev);
179 	if (!np)
180 		return -ENOENT;
181 
182 	match = of_match_node(cpu_opp_match_list, np);
183 	if (!match)
184 		return -ENOENT;
185 
186 	opp_data = match->data;
187 
188 	speedbin_nvmem = of_nvmem_cell_get(np, NULL);
189 	if (IS_ERR(speedbin_nvmem))
190 		return dev_err_probe(cpu_dev, PTR_ERR(speedbin_nvmem),
191 				     "Could not get nvmem cell\n");
192 
193 	speedbin = nvmem_cell_read(speedbin_nvmem, NULL);
194 	nvmem_cell_put(speedbin_nvmem);
195 	if (IS_ERR(speedbin))
196 		return PTR_ERR(speedbin);
197 
198 	ret = opp_data->efuse_xlate(*speedbin);
199 
200 	kfree(speedbin);
201 
202 	return ret;
203 };
204 
205 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
206 {
207 	int *opp_tokens;
208 	char name[] = "speedXXXXXXXXXXX"; /* Integers can take 11 chars max */
209 	unsigned int cpu, supported_hw;
210 	struct dev_pm_opp_config config = {};
211 	int speed;
212 	int ret;
213 
214 	opp_tokens = kcalloc(num_possible_cpus(), sizeof(*opp_tokens),
215 			     GFP_KERNEL);
216 	if (!opp_tokens)
217 		return -ENOMEM;
218 
219 	speed = sun50i_cpufreq_get_efuse();
220 	if (speed < 0) {
221 		kfree(opp_tokens);
222 		return speed;
223 	}
224 
225 	/*
226 	 * We need at least one OPP with the "opp-supported-hw" property,
227 	 * or else the upper layers will ignore every OPP and will bail out.
228 	 */
229 	if (dt_has_supported_hw()) {
230 		supported_hw = 1U << speed;
231 		config.supported_hw = &supported_hw;
232 		config.supported_hw_count = 1;
233 	}
234 
235 	snprintf(name, sizeof(name), "speed%d", speed);
236 	config.prop_name = name;
237 
238 	for_each_possible_cpu(cpu) {
239 		struct device *cpu_dev = get_cpu_device(cpu);
240 
241 		if (!cpu_dev) {
242 			ret = -ENODEV;
243 			goto free_opp;
244 		}
245 
246 		ret = dev_pm_opp_set_config(cpu_dev, &config);
247 		if (ret < 0)
248 			goto free_opp;
249 
250 		opp_tokens[cpu] = ret;
251 	}
252 
253 	cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
254 							  NULL, 0);
255 	if (!IS_ERR(cpufreq_dt_pdev)) {
256 		platform_set_drvdata(pdev, opp_tokens);
257 		return 0;
258 	}
259 
260 	ret = PTR_ERR(cpufreq_dt_pdev);
261 	pr_err("Failed to register platform device\n");
262 
263 free_opp:
264 	for_each_possible_cpu(cpu)
265 		dev_pm_opp_clear_config(opp_tokens[cpu]);
266 	kfree(opp_tokens);
267 
268 	return ret;
269 }
270 
271 static void sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
272 {
273 	int *opp_tokens = platform_get_drvdata(pdev);
274 	unsigned int cpu;
275 
276 	platform_device_unregister(cpufreq_dt_pdev);
277 
278 	for_each_possible_cpu(cpu)
279 		dev_pm_opp_clear_config(opp_tokens[cpu]);
280 
281 	kfree(opp_tokens);
282 }
283 
284 static struct platform_driver sun50i_cpufreq_driver = {
285 	.probe = sun50i_cpufreq_nvmem_probe,
286 	.remove_new = sun50i_cpufreq_nvmem_remove,
287 	.driver = {
288 		.name = "sun50i-cpufreq-nvmem",
289 	},
290 };
291 
292 static const struct of_device_id sun50i_cpufreq_match_list[] = {
293 	{ .compatible = "allwinner,sun50i-h6" },
294 	{ .compatible = "allwinner,sun50i-h616" },
295 	{ .compatible = "allwinner,sun50i-h618" },
296 	{ .compatible = "allwinner,sun50i-h700" },
297 	{}
298 };
299 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
300 
301 static const struct of_device_id *sun50i_cpufreq_match_node(void)
302 {
303 	struct device_node *np __free(device_node) = of_find_node_by_path("/");
304 
305 	return of_match_node(sun50i_cpufreq_match_list, np);
306 }
307 
308 /*
309  * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
310  * all the real activity is done in the probe, which may be defered as well.
311  * The init here is only registering the driver and the platform device.
312  */
313 static int __init sun50i_cpufreq_init(void)
314 {
315 	const struct of_device_id *match;
316 	int ret;
317 
318 	match = sun50i_cpufreq_match_node();
319 	if (!match)
320 		return -ENODEV;
321 
322 	ret = platform_driver_register(&sun50i_cpufreq_driver);
323 	if (unlikely(ret < 0))
324 		return ret;
325 
326 	sun50i_cpufreq_pdev =
327 		platform_device_register_simple("sun50i-cpufreq-nvmem",
328 						-1, NULL, 0);
329 	ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
330 	if (ret == 0)
331 		return 0;
332 
333 	platform_driver_unregister(&sun50i_cpufreq_driver);
334 	return ret;
335 }
336 module_init(sun50i_cpufreq_init);
337 
338 static void __exit sun50i_cpufreq_exit(void)
339 {
340 	platform_device_unregister(sun50i_cpufreq_pdev);
341 	platform_driver_unregister(&sun50i_cpufreq_driver);
342 }
343 module_exit(sun50i_cpufreq_exit);
344 
345 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
346 MODULE_LICENSE("GPL v2");
347