基于sys文件系统的LED驱动的移植【原创】 |
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基于sys文件系统的LED驱动的移植【原创】
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基于RK3188平台LED驱动程序的移植的移植。如有不正确之处，欢迎大家指点。 本文的LED驱动程序不是通过打开设备节点来访问和控制LED的，是通过sys文件系统来控制LED。 板子上有四盏灯以及对应的GPIO的引脚如下：
基于sys文件系统的LED驱动内核已经提供了，我们需要做的事情没有那么多。内核通过的LED驱动程序走的是平台总线的方式，板级文件Board-rk3188-u4301.c (kernel\arch\arm\mach-rk3188) 里添加LED的GPIO的信息。 1 static struct gpio_led rk29_leds[] = { 2 { 3 .name = "power", //在/sys/class/leds/ 目录下显示的文件名 4 .gpio = RK30_PIN0_PB4, //LED的GPIO口的引脚 5 .default_state = LEDS_GPIO_DEFSTATE_OFF, //设置默认的状态 6 }, 7 { 8 .name = "paper", 9 .gpio = RK30_PIN0_PB5, 10 .default_state = LEDS_GPIO_DEFSTATE_OFF, 11 }, 12 { 13 .name = "connect", 14 .gpio = RK30_PIN0_PB6, 15 .default_state = LEDS_GPIO_DEFSTATE_OFF, 16 }, 17 { 18 .name = "status", 19 .gpio = RK30_PIN0_PB7, 20 .default_state = LEDS_GPIO_DEFSTATE_OFF, 21 }, 22 }; 23 24 static struct gpio_led_platform_data rk29_leds_pdata = { 25 .leds = rk29_leds, 26 .num_leds = ARRAY_SIZE(rk29_leds), 27 }; 28 29 static struct platform_device rk29_device_gpio_leds = { 30 .name = "leds-gpio", //设备的名称，驱动就是根据这个文件匹配的啊。 31 .id = -1, 32 .dev = { 33 .platform_data = &rk29_leds_pdata, 34 }, 35 };我们在看看驱动文件Leds-gpio.c (\\192.168.1.144\zsf\rk3188_5.1\android\kernel\drivers\leds)  
1 /*
2 * LEDs driver for GPIOs
3 *
4 * Copyright (C) 2007 8D Technologies inc.
5 * Raphael Assenat
6 * Copyright (C) 2008 Freescale Semiconductor, Inc.
7 *
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
11 *
12 */
13 #include
14 #include
15 #include
16 #include
17 #include
18 #include
19 #include
20 #include
21
22 #include
23
24 struct gpio_led_data {
25 struct led_classdev cdev;
26 unsigned gpio;
27 struct work_struct work;
28 u8 new_level;
29 u8 can_sleep;
30 u8 active_low;
31 u8 blinking;
32 int (*platform_gpio_blink_set)(unsigned gpio, int state,
33 unsigned long *delay_on, unsigned long *delay_off);
34 };
35
36 static void gpio_led_work(struct work_struct *work)
37 {
38 struct gpio_led_data *led_dat =
39 container_of(work, struct gpio_led_data, work);
40
41 if (led_dat->blinking) {
42 led_dat->platform_gpio_blink_set(led_dat->gpio,
43 led_dat->new_level,
44 NULL, NULL);
45 led_dat->blinking = 0;
46 } else
47 gpio_set_value_cansleep(led_dat->gpio, led_dat->new_level);
48 }
49
50 static void gpio_led_set(struct led_classdev *led_cdev,
51 enum led_brightness value)
52 {
53 struct gpio_led_data *led_dat =
54 container_of(led_cdev, struct gpio_led_data, cdev);
55 int level;
56
57 if (value == LED_OFF)
58 level = 0;
59 else
60 level = 1;
61
62 if (led_dat->active_low)
63 level = !level;
64
65 /* Setting GPIOs with I2C/etc requires a task context, and we don't
66 * seem to have a reliable way to know if we're already in one; so
67 * let's just assume the worst.
68 */
69 if (led_dat->can_sleep) {
70 led_dat->new_level = level;
71 schedule_work(&led_dat->work);
72 } else {
73 if (led_dat->blinking) {
74 led_dat->platform_gpio_blink_set(led_dat->gpio, level,
75 NULL, NULL);
76 led_dat->blinking = 0;
77 } else
78 gpio_set_value(led_dat->gpio, level);
79 }
80 }
81
82 static int gpio_blink_set(struct led_classdev *led_cdev,
83 unsigned long *delay_on, unsigned long *delay_off)
84 {
85 struct gpio_led_data *led_dat =
86 container_of(led_cdev, struct gpio_led_data, cdev);
87
88 led_dat->blinking = 1;
89 return led_dat->platform_gpio_blink_set(led_dat->gpio, GPIO_LED_BLINK,
90 delay_on, delay_off);
91 }
92
93 static int __devinit create_gpio_led(const struct gpio_led *template,
94 struct gpio_led_data *led_dat, struct device *parent,
95 int (*blink_set)(unsigned, int, unsigned long *, unsigned long *))
96 {
97 int ret, state;
98
99 led_dat->gpio = -1;
100
101 /* skip leds that aren't available */
102 if (!gpio_is_valid(template->gpio)) {
103 printk(KERN_INFO "Skipping unavailable LED gpio %d (%s)\n",
104 template->gpio, template->name);
105 return 0;
106 }
107
108 ret = gpio_request(template->gpio, template->name);
109 if (ret < 0)
110 return ret;
111
112 led_dat->cdev.name = template->name;
113 led_dat->cdev.default_trigger = template->default_trigger;
114 led_dat->gpio = template->gpio;
115 led_dat->can_sleep = gpio_cansleep(template->gpio);
116 led_dat->active_low = template->active_low;
117 led_dat->blinking = 0;
118 if (blink_set) {
119 led_dat->platform_gpio_blink_set = blink_set;
120 led_dat->cdev.blink_set = gpio_blink_set;
121 }
122 led_dat->cdev.brightness_set = gpio_led_set;
123 if (template->default_state == LEDS_GPIO_DEFSTATE_KEEP)
124 state = !!gpio_get_value(led_dat->gpio) ^ led_dat->active_low;
125 else
126 state = (template->default_state == LEDS_GPIO_DEFSTATE_ON);
127 led_dat->cdev.brightness = state ? LED_FULL : LED_OFF;
128 if (!template->retain_state_suspended)
129 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
130
131 ret = gpio_direction_output(led_dat->gpio, led_dat->active_low ^ state);
132 if (ret < 0)
133 goto err;
134
135 INIT_WORK(&led_dat->work, gpio_led_work);
136
137 ret = led_classdev_register(parent, &led_dat->cdev);
138 if (ret < 0)
139 goto err;
140
141 return 0;
142 err:
143 gpio_free(led_dat->gpio);
144 return ret;
145 }
146
147 static void delete_gpio_led(struct gpio_led_data *led)
148 {
149 if (!gpio_is_valid(led->gpio))
150 return;
151 led_classdev_unregister(&led->cdev);
152 cancel_work_sync(&led->work);
153 gpio_free(led->gpio);
154 }
155
156 struct gpio_leds_priv {
157 int num_leds;
158 struct gpio_led_data leds[];
159 };
160
161 static inline int sizeof_gpio_leds_priv(int num_leds)
162 {
163 return sizeof(struct gpio_leds_priv) +
164 (sizeof(struct gpio_led_data) * num_leds);
165 }
166
167 /* Code to create from OpenFirmware platform devices */
168 #ifdef CONFIG_LEDS_GPIO_OF
169 static struct gpio_leds_priv * __devinit gpio_leds_create_of(struct platform_device *pdev)
170 {
171 struct device_node *np = pdev->dev.of_node, *child;
172 struct gpio_leds_priv *priv;
173 int count = 0, ret;
174
175 /* count LEDs in this device, so we know how much to allocate */
176 for_each_child_of_node(np, child)
177 count++;
178 if (!count)
179 return NULL;
180
181 priv = kzalloc(sizeof_gpio_leds_priv(count), GFP_KERNEL);
182 if (!priv)
183 return NULL;
184
185 for_each_child_of_node(np, child) {
186 struct gpio_led led = {};
187 enum of_gpio_flags flags;
188 const char *state;
189
190 led.gpio = of_get_gpio_flags(child, 0, &flags);
191 led.active_low = flags & OF_GPIO_ACTIVE_LOW;
192 led.name = of_get_property(child, "label", NULL) ? : child->name;
193 led.default_trigger =
194 of_get_property(child, "linux,default-trigger", NULL);
195 state = of_get_property(child, "default-state", NULL);
196 if (state) {
197 if (!strcmp(state, "keep"))
198 led.default_state = LEDS_GPIO_DEFSTATE_KEEP;
199 else if (!strcmp(state, "on"))
200 led.default_state = LEDS_GPIO_DEFSTATE_ON;
201 else
202 led.default_state = LEDS_GPIO_DEFSTATE_OFF;
203 }
204
205 ret = create_gpio_led(&led, &priv->leds[priv->num_leds++],
206 &pdev->dev, NULL);
207 if (ret < 0) {
208 of_node_put(child);
209 goto err;
210 }
211 }
212
213 return priv;
214
215 err:
216 for (count = priv->num_leds - 2; count >= 0; count--)
217 delete_gpio_led(&priv->leds[count]);
218 kfree(priv);
219 return NULL;
220 }
221
222 static const struct of_device_id of_gpio_leds_match[] = {
223 { .compatible = "gpio-leds", },
224 {},
225 };
226 #else
227 static struct gpio_leds_priv * __devinit gpio_leds_create_of(struct platform_device *pdev)
228 {
229 return NULL;
230 }
231 #define of_gpio_leds_match NULL
232 #endif
233
234
235 static int __devinit gpio_led_probe(struct platform_device *pdev)
236 {
237 struct gpio_led_platform_data *pdata = pdev->dev.platform_data;
238 struct gpio_leds_priv *priv;
239 int i, ret = 0;
240
241 if (pdata && pdata->num_leds) {
242 priv = kzalloc(sizeof_gpio_leds_priv(pdata->num_leds),
243 GFP_KERNEL);
244 if (!priv)
245 return -ENOMEM;
246
247 priv->num_leds = pdata->num_leds;
248 for (i = 0; i < priv->num_leds; i++) {
249 ret = create_gpio_led(&pdata->leds[i],
250 &priv->leds[i],
251 &pdev->dev, pdata->gpio_blink_set);
252 if (ret < 0) {
253 /* On failure: unwind the led creations */
254 for (i = i - 1; i >= 0; i--)
255 delete_gpio_led(&priv->leds[i]);
256 kfree(priv);
257 return ret;
258 }
259 }
260 } else {
261 priv = gpio_leds_create_of(pdev);
262 if (!priv)
263 return -ENODEV;
264 }
265
266 platform_set_drvdata(pdev, priv);
267
268 return 0;
269 }
270
271 static int __devexit gpio_led_remove(struct platform_device *pdev)
272 {
273 struct gpio_leds_priv *priv = dev_get_drvdata(&pdev->dev);
274 int i;
275
276 for (i = 0; i < priv->num_leds; i++)
277 delete_gpio_led(&priv->leds[i]);
278
279 dev_set_drvdata(&pdev->dev, NULL);
280 kfree(priv);
281
282 return 0;
283 }
284
285 static struct platform_driver gpio_led_driver = {
286 .probe = gpio_led_probe,
287 .remove = __devexit_p(gpio_led_remove),
288 .driver = {
289 .name = "leds-gpio",
290 .owner = THIS_MODULE,
291 .of_match_table = of_gpio_leds_match,
292 },
293 };
294
295 MODULE_ALIAS("platform:leds-gpio");
296
297 static int __init gpio_led_init(void)
298 {
299 printk(KERN_ERR"zbzhuang leds");
300
301
302 return platform_driver_register(&gpio_led_driver);
303 }
304
305 static void __exit gpio_led_exit(void)
306 {
307 platform_driver_unregister(&gpio_led_driver);
308 }
309
310 module_init(gpio_led_init);
311 module_exit(gpio_led_exit);
312
313 MODULE_AUTHOR("Raphael Assenat , Trent Piepho ");
314 MODULE_DESCRIPTION("GPIO LED driver");
315 MODULE_LICENSE("GPL");
View Code
驱动文件就是根据名字跟 设备进行匹配。匹配成功之后就会在创建sys文件系统提供接口给应用程序控制设备。
在内核执行make menuconfig，要配置LED驱动的一些功能如闪烁和呼吸灯等功能，编译进内核。
重新烧录开发板的内核。之后通过串口进入开发板。在/sys/class/leds目录下创建出了，我们板级文件下添加的4个LED驱动。
下面我们演示如何通过sys文件系统控制LED的亮灭。进入connect目录。执行下面三条命令就可控制LED灯的亮灭和进入呼吸灯的模式。
觉得不错，就给我点小支持吧，蟹蟹
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