1/*
  2 * System Control Driver
  3 *
  4 * Copyright (C) 2012 Freescale Semiconductor, Inc.
  5 * Copyright (C) 2012 Linaro Ltd.
  6 *
  7 * Author: Dong Aisheng <dong.aisheng@linaro.org>
  8 *
  9 * This program is free software; you can redistribute it and/or modify
 10 * it under the terms of the GNU General Public License as published by
 11 * the Free Software Foundation; either version 2 of the License, or
 12 * (at your option) any later version.
 13 */
 14
 15#include <linux/err.h>
 16#include <linux/io.h>
 17#include <linux/module.h>
 18#include <linux/list.h>
 19#include <linux/of.h>
 20#include <linux/of_address.h>
 21#include <linux/of_platform.h>
 22#include <linux/platform_data/syscon.h>
 23#include <linux/platform_device.h>
 24#include <linux/regmap.h>
 25#include <linux/mfd/syscon.h>
 26#include <linux/slab.h>
 27
 28static struct platform_driver syscon_driver;
 29
 30static DEFINE_SPINLOCK(syscon_list_slock);
 31static LIST_HEAD(syscon_list);
 32
 33struct syscon {
 34	struct device_node *np;
 35	struct regmap *regmap;
 36	struct list_head list;
 37};
 38
 39static const struct regmap_config syscon_regmap_config = {
 40	.reg_bits = 32,
 41	.val_bits = 32,
 42	.reg_stride = 4,
 43};
 44
 45static struct syscon *of_syscon_register(struct device_node *np)
 46{
 47	struct syscon *syscon;
 48	struct regmap *regmap;
 49	void __iomem *base;
 50	u32 reg_io_width;
 51	int ret;
 52	struct regmap_config syscon_config = syscon_regmap_config;
 53	struct resource res;
 54
 55	if (!of_device_is_compatible(np, "syscon"))
 56		return ERR_PTR(-EINVAL);
 57
 58	syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
 59	if (!syscon)
 60		return ERR_PTR(-ENOMEM);
 61
 62	if (of_address_to_resource(np, 0, &res)) {
 63		ret = -ENOMEM;
 64		goto err_map;
 65	}
 66
 67	base = ioremap(res.start, resource_size(&res));
 68	if (!base) {
 69		ret = -ENOMEM;
 70		goto err_map;
 71	}
 72
 73	/* Parse the device's DT node for an endianness specification */
 74	if (of_property_read_bool(np, "big-endian"))
 75		syscon_config.val_format_endian = REGMAP_ENDIAN_BIG;
 76	else if (of_property_read_bool(np, "little-endian"))
 77		syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE;
 78	else if (of_property_read_bool(np, "native-endian"))
 79		syscon_config.val_format_endian = REGMAP_ENDIAN_NATIVE;
 80
 81	/*
 82	 * search for reg-io-width property in DT. If it is not provided,
 83	 * default to 4 bytes. regmap_init_mmio will return an error if values
 84	 * are invalid so there is no need to check them here.
 85	 */
 86	ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
 87	if (ret)
 88		reg_io_width = 4;
 89
 90	syscon_config.reg_stride = reg_io_width;
 91	syscon_config.val_bits = reg_io_width * 8;
 92	syscon_config.max_register = resource_size(&res) - reg_io_width;
 93
 94	regmap = regmap_init_mmio(NULL, base, &syscon_config);
 95	if (IS_ERR(regmap)) {
 96		pr_err("regmap init failed\n");
 97		ret = PTR_ERR(regmap);
 98		goto err_regmap;
 99	}
100
101	syscon->regmap = regmap;
102	syscon->np = np;
103
104	spin_lock(&syscon_list_slock);
105	list_add_tail(&syscon->list, &syscon_list);
106	spin_unlock(&syscon_list_slock);
107
108	return syscon;
109
110err_regmap:
111	iounmap(base);
112err_map:
113	kfree(syscon);
114	return ERR_PTR(ret);
115}
116
117struct regmap *syscon_node_to_regmap(struct device_node *np)
118{
119	struct syscon *entry, *syscon = NULL;
120
121	spin_lock(&syscon_list_slock);
122
123	list_for_each_entry(entry, &syscon_list, list)
124		if (entry->np == np) {
125			syscon = entry;
126			break;
127		}
128
129	spin_unlock(&syscon_list_slock);
130
131	if (!syscon)
132		syscon = of_syscon_register(np);
133
134	if (IS_ERR(syscon))
135		return ERR_CAST(syscon);
136
137	return syscon->regmap;
138}
139EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
140
141struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
142{
143	struct device_node *syscon_np;
144	struct regmap *regmap;
145
146	syscon_np = of_find_compatible_node(NULL, NULL, s);
147	if (!syscon_np)
148		return ERR_PTR(-ENODEV);
149
150	regmap = syscon_node_to_regmap(syscon_np);
151	of_node_put(syscon_np);
152
153	return regmap;
154}
155EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);
156
157static int syscon_match_pdevname(struct device *dev, void *data)
158{
159	return !strcmp(dev_name(dev), (const char *)data);
160}
161
162struct regmap *syscon_regmap_lookup_by_pdevname(const char *s)
163{
164	struct device *dev;
165	struct syscon *syscon;
166
167	dev = driver_find_device(&syscon_driver.driver, NULL, (void *)s,
168				 syscon_match_pdevname);
169	if (!dev)
170		return ERR_PTR(-EPROBE_DEFER);
171
172	syscon = dev_get_drvdata(dev);
173
174	return syscon->regmap;
175}
176EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_pdevname);
177
178struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
179					const char *property)
180{
181	struct device_node *syscon_np;
182	struct regmap *regmap;
183
184	if (property)
185		syscon_np = of_parse_phandle(np, property, 0);
186	else
187		syscon_np = np;
188
189	if (!syscon_np)
190		return ERR_PTR(-ENODEV);
191
192	regmap = syscon_node_to_regmap(syscon_np);
193	of_node_put(syscon_np);
194
195	return regmap;
196}
197EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
198
199static int syscon_probe(struct platform_device *pdev)
200{
201	struct device *dev = &pdev->dev;
202	struct syscon_platform_data *pdata = dev_get_platdata(dev);
203	struct syscon *syscon;
204	struct regmap_config syscon_config = syscon_regmap_config;
205	struct resource *res;
206	void __iomem *base;
207
208	syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
209	if (!syscon)
210		return -ENOMEM;
211
212	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
213	if (!res)
214		return -ENOENT;
215
216	base = devm_ioremap(dev, res->start, resource_size(res));
217	if (!base)
218		return -ENOMEM;
219
220	syscon_config.max_register = res->end - res->start - 3;
221	if (pdata)
222		syscon_config.name = pdata->label;
223	syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);
224	if (IS_ERR(syscon->regmap)) {
225		dev_err(dev, "regmap init failed\n");
226		return PTR_ERR(syscon->regmap);
227	}
228
229	platform_set_drvdata(pdev, syscon);
230
231	dev_dbg(dev, "regmap %pR registered\n", res);
232
233	return 0;
234}
235
236static const struct platform_device_id syscon_ids[] = {
237	{ "syscon", },
238	{ }
239};
240
241static struct platform_driver syscon_driver = {
242	.driver = {
243		.name = "syscon",
244	},
245	.probe		= syscon_probe,
246	.id_table	= syscon_ids,
247};
248
249static int __init syscon_init(void)
250{
251	return platform_driver_register(&syscon_driver);
252}
253postcore_initcall(syscon_init);
254
255static void __exit syscon_exit(void)
256{
257	platform_driver_unregister(&syscon_driver);
258}
259module_exit(syscon_exit);
260
261MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
262MODULE_DESCRIPTION("System Control driver");
263MODULE_LICENSE("GPL v2");