syscon.c

  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/list.h>
 16#include <linux/mutex.h>
 17#include <linux/of.h>
 18#include <linux/of_address.h>
 19#include <linux/regmap.h>
 20#include <linux/reset.h>
 21#include <linux/mfd/syscon.h>
 22#include <linux/slab.h>
 23
 24static DEFINE_MUTEX(syscon_list_lock);
 25static LIST_HEAD(syscon_list);
 26
 27struct syscon {
 28	struct device_node *np;
 29	struct regmap *regmap;
 30	struct reset_control *reset;
 31	struct list_head list;
 32};
 33
 34static const struct regmap_config syscon_regmap_config = {
 35	.reg_bits = 32,
 36	.val_bits = 32,
 37	.reg_stride = 4,
 38};
 39
 40static struct syscon *of_syscon_register(struct device_node *np, bool check_res)
 41{
 42	struct clk *clk;
 43	struct regmap *regmap;
 44	void __iomem *base;
 45	u32 reg_io_width;
 46	int ret;
 47	struct regmap_config syscon_config = syscon_regmap_config;
 48	struct resource res;
 49	struct reset_control *reset;
 50	resource_size_t res_size;
 51
 52	WARN_ON(!mutex_is_locked(&syscon_list_lock));
 53
 54	struct syscon *syscon __free(kfree) = kzalloc(sizeof(*syscon), GFP_KERNEL);
 55	if (!syscon)
 56		return ERR_PTR(-ENOMEM);
 57
 58	if (of_address_to_resource(np, 0, &res))
 59		return ERR_PTR(-ENOMEM);
 60
 61	base = of_iomap(np, 0);
 62	if (!base)
 63		return ERR_PTR(-ENOMEM);
 64
 65	/* Parse the device's DT node for an endianness specification */
 66	if (of_property_read_bool(np, "big-endian"))
 67		syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;
 68	else if (of_property_read_bool(np, "little-endian"))
 69		syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
 70	else if (of_property_read_bool(np, "native-endian"))
 71		syscon_config.val_format_endian = REGMAP_ENDIAN_NATIVE;
 72
 73	/*
 74	 * search for reg-io-width property in DT. If it is not provided,
 75	 * default to 4 bytes. regmap_init_mmio will return an error if values
 76	 * are invalid so there is no need to check them here.
 77	 */
 78	ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
 79	if (ret)
 80		reg_io_width = 4;
 81
 82	ret = of_hwspin_lock_get_id(np, 0);
 83	if (ret > 0 || (IS_ENABLED(CONFIG_HWSPINLOCK) && ret == 0)) {
 84		syscon_config.use_hwlock = true;
 85		syscon_config.hwlock_id = ret;
 86		syscon_config.hwlock_mode = HWLOCK_IRQSTATE;
 87	} else if (ret < 0) {
 88		switch (ret) {
 89		case -ENOENT:
 90			/* Ignore missing hwlock, it's optional. */
 91			break;
 92		default:
 93			pr_err("Failed to retrieve valid hwlock: %d\n", ret);
 94			fallthrough;
 95		case -EPROBE_DEFER:
 96			goto err_regmap;
 97		}
 98	}
 99
100	res_size = resource_size(&res);
101	if (res_size < reg_io_width) {
102		ret = -EFAULT;
103		goto err_regmap;
104	}
105
106	syscon_config.name = kasprintf(GFP_KERNEL, "%pOFn@%pa", np, &res.start);
107	if (!syscon_config.name) {
108		ret = -ENOMEM;
109		goto err_regmap;
110	}
111	syscon_config.reg_stride = reg_io_width;
112	syscon_config.val_bits = reg_io_width * 8;
113	syscon_config.max_register = res_size - reg_io_width;
114	if (!syscon_config.max_register)
115		syscon_config.max_register_is_0 = true;
116
117	regmap = regmap_init_mmio(NULL, base, &syscon_config);
118	kfree(syscon_config.name);
119	if (IS_ERR(regmap)) {
120		pr_err("regmap init failed\n");
121		ret = PTR_ERR(regmap);
122		goto err_regmap;
123	}
124
125	if (check_res) {
126		clk = of_clk_get(np, 0);
127		if (IS_ERR(clk)) {
128			ret = PTR_ERR(clk);
129			/* clock is optional */
130			if (ret != -ENOENT)
131				goto err_clk;
132		} else {
133			ret = regmap_mmio_attach_clk(regmap, clk);
134			if (ret)
135				goto err_attach_clk;
136		}
137
138		reset = of_reset_control_get_optional_exclusive(np, NULL);
139		if (IS_ERR(reset)) {
140			ret = PTR_ERR(reset);
141			goto err_attach_clk;
142		}
143
144		ret = reset_control_deassert(reset);
145		if (ret)
146			goto err_reset;
147	}
148
149	syscon->regmap = regmap;
150	syscon->np = np;
151
152	list_add_tail(&syscon->list, &syscon_list);
153
154	return_ptr(syscon);
155
156err_reset:
157	reset_control_put(reset);
158err_attach_clk:
159	if (!IS_ERR(clk))
160		clk_put(clk);
161err_clk:
162	regmap_exit(regmap);
163err_regmap:
164	iounmap(base);
165	return ERR_PTR(ret);
166}
167
168static struct regmap *device_node_get_regmap(struct device_node *np,
169					     bool create_regmap,
170					     bool check_res)
171{
172	struct syscon *entry, *syscon = NULL;
173
174	mutex_lock(&syscon_list_lock);
175
176	list_for_each_entry(entry, &syscon_list, list)
177		if (entry->np == np) {
178			syscon = entry;
179			break;
180		}
181
182	if (!syscon) {
183		if (create_regmap)
184			syscon = of_syscon_register(np, check_res);
185		else
186			syscon = ERR_PTR(-EPROBE_DEFER);
187	}
188	mutex_unlock(&syscon_list_lock);
189
190	if (IS_ERR(syscon))
191		return ERR_CAST(syscon);
192
193	return syscon->regmap;
194}
195
196/**
197 * of_syscon_register_regmap() - Register regmap for specified device node
198 * @np: Device tree node
199 * @regmap: Pointer to regmap object
200 *
201 * Register an externally created regmap object with syscon for the specified
202 * device tree node. This regmap will then be returned to client drivers using
203 * the syscon_regmap_lookup_by_phandle() API.
204 *
205 * Return: 0 on success, negative error code on failure.
206 */
207int of_syscon_register_regmap(struct device_node *np, struct regmap *regmap)
208{
209	struct syscon *entry, *syscon = NULL;
210	int ret;
211
212	if (!np || !regmap)
213		return -EINVAL;
214
215	syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
216	if (!syscon)
217		return -ENOMEM;
218
219	/* check if syscon entry already exists */
220	mutex_lock(&syscon_list_lock);
221
222	list_for_each_entry(entry, &syscon_list, list)
223		if (entry->np == np) {
224			ret = -EEXIST;
225			goto err_unlock;
226		}
227
228	syscon->regmap = regmap;
229	syscon->np = np;
230
231	/* register the regmap in syscon list */
232	list_add_tail(&syscon->list, &syscon_list);
233	mutex_unlock(&syscon_list_lock);
234
235	return 0;
236
237err_unlock:
238	mutex_unlock(&syscon_list_lock);
239	kfree(syscon);
240	return ret;
241}
242EXPORT_SYMBOL_GPL(of_syscon_register_regmap);
243
244/**
245 * device_node_to_regmap() - Get or create a regmap for specified device node
246 * @np: Device tree node
247 *
248 * Get a regmap for the specified device node. If there's not an existing
249 * regmap, then one is instantiated. This function should not be used if the
250 * device node has a custom regmap driver or has resources (clocks, resets) to
251 * be managed. Use syscon_node_to_regmap() instead for those cases.
252 *
253 * Return: regmap ptr on success, negative error code on failure.
254 */
255struct regmap *device_node_to_regmap(struct device_node *np)
256{
257	return device_node_get_regmap(np, true, false);
258}
259EXPORT_SYMBOL_GPL(device_node_to_regmap);
260
261/**
262 * syscon_node_to_regmap() - Get or create a regmap for specified syscon device node
263 * @np: Device tree node
264 *
265 * Get a regmap for the specified device node. If there's not an existing
266 * regmap, then one is instantiated if the node is a generic "syscon". This
267 * function is safe to use for a syscon registered with
268 * of_syscon_register_regmap().
269 *
270 * Return: regmap ptr on success, negative error code on failure.
271 */
272struct regmap *syscon_node_to_regmap(struct device_node *np)
273{
274	return device_node_get_regmap(np, of_device_is_compatible(np, "syscon"), true);
275}
276EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
277
278struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
279{
280	struct device_node *syscon_np;
281	struct regmap *regmap;
282
283	syscon_np = of_find_compatible_node(NULL, NULL, s);
284	if (!syscon_np)
285		return ERR_PTR(-ENODEV);
286
287	regmap = syscon_node_to_regmap(syscon_np);
288	of_node_put(syscon_np);
289
290	return regmap;
291}
292EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);
293
294struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
295					const char *property)
296{
297	struct device_node *syscon_np;
298	struct regmap *regmap;
299
300	if (property)
301		syscon_np = of_parse_phandle(np, property, 0);
302	else
303		syscon_np = np;
304
305	if (!syscon_np)
306		return ERR_PTR(-ENODEV);
307
308	regmap = syscon_node_to_regmap(syscon_np);
309
310	if (property)
311		of_node_put(syscon_np);
312
313	return regmap;
314}
315EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
316
317struct regmap *syscon_regmap_lookup_by_phandle_args(struct device_node *np,
318					const char *property,
319					int arg_count,
320					unsigned int *out_args)
321{
322	struct device_node *syscon_np;
323	struct of_phandle_args args;
324	struct regmap *regmap;
325	unsigned int index;
326	int rc;
327
328	rc = of_parse_phandle_with_fixed_args(np, property, arg_count,
329			0, &args);
330	if (rc)
331		return ERR_PTR(rc);
332
333	syscon_np = args.np;
334	if (!syscon_np)
335		return ERR_PTR(-ENODEV);
336
337	regmap = syscon_node_to_regmap(syscon_np);
338	for (index = 0; index < arg_count; index++)
339		out_args[index] = args.args[index];
340	of_node_put(syscon_np);
341
342	return regmap;
343}
344EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_args);
345
346/*
347 * It behaves the same as syscon_regmap_lookup_by_phandle() except where
348 * there is no regmap phandle. In this case, instead of returning -ENODEV,
349 * the function returns NULL.
350 */
351struct regmap *syscon_regmap_lookup_by_phandle_optional(struct device_node *np,
352					const char *property)
353{
354	struct regmap *regmap;
355
356	regmap = syscon_regmap_lookup_by_phandle(np, property);
357	if (IS_ERR(regmap) && PTR_ERR(regmap) == -ENODEV)
358		return NULL;
359
360	return regmap;
361}
362EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle_optional);