1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * System Control Driver
4  *
5  * Copyright (C) 2012 Freescale Semiconductor, Inc.
6  * Copyright (C) 2012 Linaro Ltd.
7  *
8  * Author: Dong Aisheng <dong.aisheng@linaro.org>
9  */
10 
11 #include <linux/cleanup.h>
12 #include <linux/clk.h>
13 #include <linux/err.h>
14 #include <linux/hwspinlock.h>
15 #include <linux/io.h>
16 #include <linux/init.h>
17 #include <linux/list.h>
18 #include <linux/of.h>
19 #include <linux/of_address.h>
20 #include <linux/of_platform.h>
21 #include <linux/platform_data/syscon.h>
22 #include <linux/platform_device.h>
23 #include <linux/regmap.h>
24 #include <linux/reset.h>
25 #include <linux/mfd/syscon.h>
26 #include <linux/slab.h>
27 
28 static struct platform_driver syscon_driver;
29 
30 static DEFINE_SPINLOCK(syscon_list_slock);
31 static LIST_HEAD(syscon_list);
32 
33 struct syscon {
34 	struct device_node *np;
35 	struct regmap *regmap;
36 	struct reset_control *reset;
37 	struct list_head list;
38 };
39 
40 static const struct regmap_config syscon_regmap_config = {
41 	.reg_bits = 32,
42 	.val_bits = 32,
43 	.reg_stride = 4,
44 };
45 
of_syscon_register(struct device_node * np,bool check_res)46 static struct syscon *of_syscon_register(struct device_node *np, bool check_res)
47 {
48 	struct clk *clk;
49 	struct regmap *regmap;
50 	void __iomem *base;
51 	u32 reg_io_width;
52 	int ret;
53 	struct regmap_config syscon_config = syscon_regmap_config;
54 	struct resource res;
55 	struct reset_control *reset;
56 
57 	struct syscon *syscon __free(kfree) = kzalloc(sizeof(*syscon), GFP_KERNEL);
58 	if (!syscon)
59 		return ERR_PTR(-ENOMEM);
60 
61 	if (of_address_to_resource(np, 0, &res))
62 		return ERR_PTR(-ENOMEM);
63 
64 	base = of_iomap(np, 0);
65 	if (!base)
66 		return ERR_PTR(-ENOMEM);
67 
68 	/* Parse the device's DT node for an endianness specification */
69 	if (of_property_read_bool(np, "big-endian"))
70 		syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;
71 	else if (of_property_read_bool(np, "little-endian"))
72 		syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
73 	else if (of_property_read_bool(np, "native-endian"))
74 		syscon_config.val_format_endian = REGMAP_ENDIAN_NATIVE;
75 
76 	/*
77 	 * search for reg-io-width property in DT. If it is not provided,
78 	 * default to 4 bytes. regmap_init_mmio will return an error if values
79 	 * are invalid so there is no need to check them here.
80 	 */
81 	ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
82 	if (ret)
83 		reg_io_width = 4;
84 
85 	ret = of_hwspin_lock_get_id(np, 0);
86 	if (ret > 0 || (IS_ENABLED(CONFIG_HWSPINLOCK) && ret == 0)) {
87 		syscon_config.use_hwlock = true;
88 		syscon_config.hwlock_id = ret;
89 		syscon_config.hwlock_mode = HWLOCK_IRQSTATE;
90 	} else if (ret < 0) {
91 		switch (ret) {
92 		case -ENOENT:
93 			/* Ignore missing hwlock, it's optional. */
94 			break;
95 		default:
96 			pr_err("Failed to retrieve valid hwlock: %d\n", ret);
97 			fallthrough;
98 		case -EPROBE_DEFER:
99 			goto err_regmap;
100 		}
101 	}
102 
103 	syscon_config.name = kasprintf(GFP_KERNEL, "%pOFn@%pa", np, &res.start);
104 	if (!syscon_config.name) {
105 		ret = -ENOMEM;
106 		goto err_regmap;
107 	}
108 	syscon_config.reg_stride = reg_io_width;
109 	syscon_config.val_bits = reg_io_width * 8;
110 	syscon_config.max_register = resource_size(&res) - reg_io_width;
111 
112 	regmap = regmap_init_mmio(NULL, base, &syscon_config);
113 	kfree(syscon_config.name);
114 	if (IS_ERR(regmap)) {
115 		pr_err("regmap init failed\n");
116 		ret = PTR_ERR(regmap);
117 		goto err_regmap;
118 	}
119 
120 	if (check_res) {
121 		clk = of_clk_get(np, 0);
122 		if (IS_ERR(clk)) {
123 			ret = PTR_ERR(clk);
124 			/* clock is optional */
125 			if (ret != -ENOENT)
126 				goto err_clk;
127 		} else {
128 			ret = regmap_mmio_attach_clk(regmap, clk);
129 			if (ret)
130 				goto err_attach_clk;
131 		}
132 
133 		reset = of_reset_control_get_optional_exclusive(np, NULL);
134 		if (IS_ERR(reset)) {
135 			ret = PTR_ERR(reset);
136 			goto err_attach_clk;
137 		}
138 
139 		ret = reset_control_deassert(reset);
140 		if (ret)
141 			goto err_reset;
142 	}
143 
144 	syscon->regmap = regmap;
145 	syscon->np = np;
146 
147 	spin_lock(&syscon_list_slock);
148 	list_add_tail(&syscon->list, &syscon_list);
149 	spin_unlock(&syscon_list_slock);
150 
151 	return_ptr(syscon);
152 
153 err_reset:
154 	reset_control_put(reset);
155 err_attach_clk:
156 	if (!IS_ERR(clk))
157 		clk_put(clk);
158 err_clk:
159 	regmap_exit(regmap);
160 err_regmap:
161 	iounmap(base);
162 	return ERR_PTR(ret);
163 }
164 
device_node_get_regmap(struct device_node * np,bool check_res)165 static struct regmap *device_node_get_regmap(struct device_node *np,
166 					     bool check_res)
167 {
168 	struct syscon *entry, *syscon = NULL;
169 
170 	spin_lock(&syscon_list_slock);
171 
172 	list_for_each_entry(entry, &syscon_list, list)
173 		if (entry->np == np) {
174 			syscon = entry;
175 			break;
176 		}
177 
178 	spin_unlock(&syscon_list_slock);
179 
180 	if (!syscon)
181 		syscon = of_syscon_register(np, check_res);
182 
183 	if (IS_ERR(syscon))
184 		return ERR_CAST(syscon);
185 
186 	return syscon->regmap;
187 }
188 
189 /**
190  * of_syscon_register_regmap() - Register regmap for specified device node
191  * @np: Device tree node
192  * @regmap: Pointer to regmap object
193  *
194  * Register an externally created regmap object with syscon for the specified
195  * device tree node. This regmap will then be returned to client drivers using
196  * the syscon_regmap_lookup_by_phandle() API.
197  *
198  * Return: 0 on success, negative error code on failure.
199  */
of_syscon_register_regmap(struct device_node * np,struct regmap * regmap)200 int of_syscon_register_regmap(struct device_node *np, struct regmap *regmap)
201 {
202 	struct syscon *entry, *syscon = NULL;
203 	int ret;
204 
205 	if (!np || !regmap)
206 		return -EINVAL;
207 
208 	syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
209 	if (!syscon)
210 		return -ENOMEM;
211 
212 	/* check if syscon entry already exists */
213 	spin_lock(&syscon_list_slock);
214 
215 	list_for_each_entry(entry, &syscon_list, list)
216 		if (entry->np == np) {
217 			ret = -EEXIST;
218 			goto err_unlock;
219 		}
220 
221 	syscon->regmap = regmap;
222 	syscon->np = np;
223 
224 	/* register the regmap in syscon list */
225 	list_add_tail(&syscon->list, &syscon_list);
226 	spin_unlock(&syscon_list_slock);
227 
228 	return 0;
229 
230 err_unlock:
231 	spin_unlock(&syscon_list_slock);
232 	kfree(syscon);
233 	return ret;
234 }
235 EXPORT_SYMBOL_GPL(of_syscon_register_regmap);
236 
device_node_to_regmap(struct device_node * np)237 struct regmap *device_node_to_regmap(struct device_node *np)
238 {
239 	return device_node_get_regmap(np, false);
240 }
241 EXPORT_SYMBOL_GPL(device_node_to_regmap);
242 
syscon_node_to_regmap(struct device_node * np)243 struct regmap *syscon_node_to_regmap(struct device_node *np)
244 {
245 	if (!of_device_is_compatible(np, "syscon"))
246 		return ERR_PTR(-EINVAL);
247 
248 	return device_node_get_regmap(np, true);
249 }
250 EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
251 
syscon_regmap_lookup_by_compatible(const char * s)252 struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
253 {
254 	struct device_node *syscon_np;
255 	struct regmap *regmap;
256 
257 	syscon_np = of_find_compatible_node(NULL, NULL, s);
258 	if (!syscon_np)
259 		return ERR_PTR(-ENODEV);
260 
261 	regmap = syscon_node_to_regmap(syscon_np);
262 	of_node_put(syscon_np);
263 
264 	return regmap;
265 }
266 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);
267 
syscon_regmap_lookup_by_phandle(struct device_node * np,const char * property)268 struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
269 					const char *property)
270 {
271 	struct device_node *syscon_np;
272 	struct regmap *regmap;
273 
274 	if (property)
275 		syscon_np = of_parse_phandle(np, property, 0);
276 	else
277 		syscon_np = np;
278 
279 	if (!syscon_np)
280 		return ERR_PTR(-ENODEV);
281 
282 	regmap = syscon_node_to_regmap(syscon_np);
283 
284 	if (property)
285 		of_node_put(syscon_np);
286 
287 	return regmap;
288 }
289 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
290 
syscon_regmap_lookup_by_phandle_args(struct device_node * np,const char * property,int arg_count,unsigned int * out_args)291 struct regmap *syscon_regmap_lookup_by_phandle_args(struct device_node *np,
292 					const char *property,
293 					int arg_count,
294 					unsigned int *out_args)
295 {
296 	struct device_node *syscon_np;
297 	struct of_phandle_args args;
298 	struct regmap *regmap;
299 	unsigned int index;
300 	int rc;
301 
302 	rc = of_parse_phandle_with_fixed_args(np, property, arg_count,
303 			0, &args);
304 	if (rc)
305 		return ERR_PTR(rc);
306 
307 	syscon_np = args.np;
308 	if (!syscon_np)
309 		return ERR_PTR(-ENODEV);
310 
311 	regmap = syscon_node_to_regmap(syscon_np);
312 	for (index = 0; index < arg_count; index++)
313 		out_args[index] = args.args[index];
314 	of_node_put(syscon_np);
315 
316 	return regmap;
317 }
318 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_args);
319 
320 /*
321  * It behaves the same as syscon_regmap_lookup_by_phandle() except where
322  * there is no regmap phandle. In this case, instead of returning -ENODEV,
323  * the function returns NULL.
324  */
syscon_regmap_lookup_by_phandle_optional(struct device_node * np,const char * property)325 struct regmap *syscon_regmap_lookup_by_phandle_optional(struct device_node *np,
326 					const char *property)
327 {
328 	struct regmap *regmap;
329 
330 	regmap = syscon_regmap_lookup_by_phandle(np, property);
331 	if (IS_ERR(regmap) && PTR_ERR(regmap) == -ENODEV)
332 		return NULL;
333 
334 	return regmap;
335 }
336 EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_optional);
337 
syscon_probe(struct platform_device * pdev)338 static int syscon_probe(struct platform_device *pdev)
339 {
340 	struct device *dev = &pdev->dev;
341 	struct syscon_platform_data *pdata = dev_get_platdata(dev);
342 	struct syscon *syscon;
343 	struct regmap_config syscon_config = syscon_regmap_config;
344 	struct resource *res;
345 	void __iomem *base;
346 
347 	syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
348 	if (!syscon)
349 		return -ENOMEM;
350 
351 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
352 	if (!res)
353 		return -ENOENT;
354 
355 	base = devm_ioremap(dev, res->start, resource_size(res));
356 	if (!base)
357 		return -ENOMEM;
358 
359 	syscon_config.max_register = resource_size(res) - 4;
360 	if (pdata)
361 		syscon_config.name = pdata->label;
362 	syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);
363 	if (IS_ERR(syscon->regmap)) {
364 		dev_err(dev, "regmap init failed\n");
365 		return PTR_ERR(syscon->regmap);
366 	}
367 
368 	platform_set_drvdata(pdev, syscon);
369 
370 	dev_dbg(dev, "regmap %pR registered\n", res);
371 
372 	return 0;
373 }
374 
375 static const struct platform_device_id syscon_ids[] = {
376 	{ "syscon", },
377 	{ }
378 };
379 
380 static struct platform_driver syscon_driver = {
381 	.driver = {
382 		.name = "syscon",
383 	},
384 	.probe		= syscon_probe,
385 	.id_table	= syscon_ids,
386 };
387 
syscon_init(void)388 static int __init syscon_init(void)
389 {
390 	return platform_driver_register(&syscon_driver);
391 }
392 postcore_initcall(syscon_init);
393