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
 79	/*
 80	 * search for reg-io-width property in DT. If it is not provided,
 81	 * default to 4 bytes. regmap_init_mmio will return an error if values
 82	 * are invalid so there is no need to check them here.
 83	 */
 84	ret = of_property_read_u32(np, "reg-io-width", &reg_io_width);
 85	if (ret)
 86		reg_io_width = 4;
 87
 88	syscon_config.reg_stride = reg_io_width;
 89	syscon_config.val_bits = reg_io_width * 8;
 90	syscon_config.max_register = resource_size(&res) - reg_io_width;
 91
 92	regmap = regmap_init_mmio(NULL, base, &syscon_config);
 93	if (IS_ERR(regmap)) {
 94		pr_err("regmap init failed\n");
 95		ret = PTR_ERR(regmap);
 96		goto err_regmap;
 97	}
 98
 99	syscon->regmap = regmap;
100	syscon->np = np;
101
102	spin_lock(&syscon_list_slock);
103	list_add_tail(&syscon->list, &syscon_list);
104	spin_unlock(&syscon_list_slock);
105
106	return syscon;
107
108err_regmap:
109	iounmap(base);
110err_map:
111	kfree(syscon);
112	return ERR_PTR(ret);
113}
114
115struct regmap *syscon_node_to_regmap(struct device_node *np)
116{
117	struct syscon *entry, *syscon = NULL;
118
119	spin_lock(&syscon_list_slock);
120
121	list_for_each_entry(entry, &syscon_list, list)
122		if (entry->np == np) {
123			syscon = entry;
124			break;
125		}
126
127	spin_unlock(&syscon_list_slock);
128
129	if (!syscon)
130		syscon = of_syscon_register(np);
131
132	if (IS_ERR(syscon))
133		return ERR_CAST(syscon);
134
135	return syscon->regmap;
136}
137EXPORT_SYMBOL_GPL(syscon_node_to_regmap);
138
139struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
140{
141	struct device_node *syscon_np;
142	struct regmap *regmap;
143
144	syscon_np = of_find_compatible_node(NULL, NULL, s);
145	if (!syscon_np)
146		return ERR_PTR(-ENODEV);
147
148	regmap = syscon_node_to_regmap(syscon_np);
149	of_node_put(syscon_np);
150
151	return regmap;
152}
153EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);
154
155static int syscon_match_pdevname(struct device *dev, void *data)
156{
157	return !strcmp(dev_name(dev), (const char *)data);
158}
159
160struct regmap *syscon_regmap_lookup_by_pdevname(const char *s)
161{
162	struct device *dev;
163	struct syscon *syscon;
164
165	dev = driver_find_device(&syscon_driver.driver, NULL, (void *)s,
166				 syscon_match_pdevname);
167	if (!dev)
168		return ERR_PTR(-EPROBE_DEFER);
169
170	syscon = dev_get_drvdata(dev);
171
172	return syscon->regmap;
173}
174EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_pdevname);
175
176struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
177					const char *property)
178{
179	struct device_node *syscon_np;
180	struct regmap *regmap;
181
182	if (property)
183		syscon_np = of_parse_phandle(np, property, 0);
184	else
185		syscon_np = np;
186
187	if (!syscon_np)
188		return ERR_PTR(-ENODEV);
189
190	regmap = syscon_node_to_regmap(syscon_np);
191	of_node_put(syscon_np);
192
193	return regmap;
194}
195EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle);
196
197static int syscon_probe(struct platform_device *pdev)
198{
199	struct device *dev = &pdev->dev;
200	struct syscon_platform_data *pdata = dev_get_platdata(dev);
201	struct syscon *syscon;
202	struct regmap_config syscon_config = syscon_regmap_config;
203	struct resource *res;
204	void __iomem *base;
205
206	syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
207	if (!syscon)
208		return -ENOMEM;
209
210	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
211	if (!res)
212		return -ENOENT;
213
214	base = devm_ioremap(dev, res->start, resource_size(res));
215	if (!base)
216		return -ENOMEM;
217
218	syscon_config.max_register = res->end - res->start - 3;
219	if (pdata)
220		syscon_config.name = pdata->label;
221	syscon->regmap = devm_regmap_init_mmio(dev, base, &syscon_config);
222	if (IS_ERR(syscon->regmap)) {
223		dev_err(dev, "regmap init failed\n");
224		return PTR_ERR(syscon->regmap);
225	}
226
227	platform_set_drvdata(pdev, syscon);
228
229	dev_dbg(dev, "regmap %pR registered\n", res);
230
231	return 0;
232}
233
234static const struct platform_device_id syscon_ids[] = {
235	{ "syscon", },
236	{ }
237};
238
239static struct platform_driver syscon_driver = {
240	.driver = {
241		.name = "syscon",
242	},
243	.probe		= syscon_probe,
244	.id_table	= syscon_ids,
245};
246
247static int __init syscon_init(void)
248{
249	return platform_driver_register(&syscon_driver);
250}
251postcore_initcall(syscon_init);
252
253static void __exit syscon_exit(void)
254{
255	platform_driver_unregister(&syscon_driver);
256}
257module_exit(syscon_exit);
258
259MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
260MODULE_DESCRIPTION("System Control driver");
261MODULE_LICENSE("GPL v2");