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平台设备驱动之平台驱动

平台设备驱动之平台驱动

2023-06-07

驱动层需要实现的结构体是struct platform_driver，它用来描述一个设备的驱动信息。

结构如下（includelinuxplatform_device.h）

1 struct platform_driver {

2 int (*probe)(struct platform_device *);//探测

3 int (*remove)(struct platform_device *);//移除

4 void (*shutdown)(struct platform_device *);//关闭

5 int (*suspend)(struct platform_device *, pm_message_t state);//挂起

6 int (*resume)(struct platform_device *);//唤醒

7 struct device_driver driver;

8 struct platform_device_id *id_table;

9 };

其中probe和remove是必需实现的，跟在设备层提到的注册和注销函数有关。其他函数根据需要，自行实现。

struct device_driver中的name成员很重要，必须要和设备层struct platform_device中的name成员相同，这样才能实现驱动层和设备层的绑定。

结构如下（includelinuxdevice.h）

struct device_driver {

const char *name;

struct bus_type *bus;

struct module *owner;

const char *mod_name; /* used for built-in modules */

bool suppress_bind_attrs; /* disables bind/unbind via sysfs */

int (*probe) (struct device *dev);

int (*remove) (struct device *dev);

void (*shutdown) (struct device *dev);

int (*suspend) (struct device *dev, pm_message_t state);

int (*resume) (struct device *dev);

const struct attribute_group **groups;

const struct dev_pm_ops *pm;

struct driver_private *p;

};

平台驱动层核心API

int platform_driver_register(struct platform_driver *drv) ( driversbaseplatform.c)

void platform_driver_unregister(struct platform_driver *drv) ( driversbaseplatform.c)

struct resource *platform_get_resource( struct platform_device *dev, unsigned int type, unsigned int num) ( driversbaseplatform.c)

int platform_get_irq( struct platform_device *dev, unsigned int num) ( driversbaseplatform.c)

平台驱动的实现步骤：

1.编写probe函数

2.编写remove函数

3.定义struct platform_drv结构，并填充这个结构（注，此结构是自己定义的，结构中包含的内容也是自己定义的；这个结构其实是将驱动函数中用到的变量，写到了一起，定义成此结构，方便了其它函数的调用）

4.在模块的初始化函数中调用platform_driver_register(struct platform_driver *drv), 以注册

5.在模块卸载函数中调用platform_driver_unregister(struct platform_driver *drv), 以注销

实现代码如下：leds_platform_driver.c

1 #include

2 #include

3 #include

5 #include

6 #include

7 #include

8 #include

9 #include

10 #include

11 #include

12 #include

13 #include

14 #include

15 #include

18 #define uint unsigned int

19 #define uchar unsigned char

21 struct led_info

22 {

23 unsigned int pin_bit;

24 };

26 struct gpioreg

27 {

28 volatile unsigned long vr_gpbcon;

29 volatile unsigned long vr_gpbdat;

30 volatile unsigned long vr_gpbup;

31 };

33 //自己定义的struct platform_drv结构

34 struct s3c2440_leds_drv{

35 dev_t dev_nr;

36 struct cdev *cdev_led;

37 struct class *led_class;

38 struct resource *ledres;

39 struct led_info *led_pdata;

40 struct device *this_device;

41 struct gpioreg *vr_gpioreg;

42 struct file_operations leds_ops;

43 };

45 #define DEVICE_NAME "s3c2440leds"

46 #define LED_ON 1

47 #define LED_OFF 0

49 static struct s3c2440_leds_drv s3c2440_leds_drv_data;

50 static int leds_open(struct inode *inode, struct file *file)

51 {

52 unsigned int tmp=0, up=0, dat=0;

53 unsigned int i=0;

54 uint pin_bit=s3c2440_leds_drv_data.led_pdata->pin_bit;

56 tmp=s3c2440_leds_drv_data.vr_gpioreg->vr_gpbcon;

57 up=s3c2440_leds_drv_data.vr_gpioreg->vr_gpbcon;

58 dat=s3c2440_leds_drv_data.vr_gpioreg->vr_gpbup;

59 printk("leds_open:1111rn");

61 for(;i<16;i++)

62 {

63 if((1< 64 { //tmp的2i位置1，2i+1位置0，其他位不变，

65 tmp&=~(3< 66 tmp|=(1< 67 up|=(1< 68 dat|=(1< 69 }

70 }

72 s3c2440_leds_drv_data.vr_gpioreg->vr_gpbcon=tmp;

73 s3c2440_leds_drv_data.vr_gpioreg->vr_gpbup=up;

74 s3c2440_leds_drv_data.vr_gpioreg->vr_gpbdat=dat;

75 return 0;

76 }

78 static long leds_ioctl(struct file *filp, uint cmd, unsigned long arg)

79 {

80 uint tmp=0,i=0,j=0;

81 uint ledbit[16]={0};

82 uint pin_bit=s3c2440_leds_drv_data.led_pdata->pin_bit;

84 for(i=0;i<16;i++)

85 {

86 if((1< 87 {

88 ledbit[j]=i;

89 //printk("ledbit[%d]:%drn",j,i)

90 j++;

91 }

92 }

93 //检查传入的led的编号是否大于led总数

94 if(arg>=j)

95 return -EINVAL;

96 mb();//防止编译器对下面的代码进行优化

97 tmp=s3c2440_leds_drv_data.vr_gpioreg->vr_gpbdat;

98 mb();

100 printk("cmd:%d tmp:%drn",cmd,tmp);

101

102 switch(cmd)

103 {

104 case LED_ON:

105 tmp &=~(1<106 s3c2440_leds_drv_data.vr_gpioreg->vr_gpbdat=tmp;

107 return 0;

108

109 case LED_OFF:

110 tmp|=1<111 s3c2440_leds_drv_data.vr_gpioreg->vr_gpbdat=tmp;

112 return 0;

113

114 default:

115 printk("ioctl() cmd is errrn");

116 return -EINVAL;

117 }

118 }

119

120 static int led_probe(struct platform_device *pdev)

121 {

122 int msize,val,err;

123 // printk("%s is callrn",_FUNCTION_);

124 printk("led_probe is callrn");

125

126 //获取平台数据

127 s3c2440_leds_drv_data.led_pdata=pdev->dev.platform_data;

128

129 if(!s3c2440_leds_drv_data.led_pdata)

130 {

131 printk("get platform_data errorn");

132 return -1;

133 }

134

135 s3c2440_leds_drv_data.ledres=platform_get_resource(pdev,IORESOURCE_MEM,0);

136 if(!s3c2440_leds_drv_data.ledres)

137 {

138 printk("get resource errorn");

139 return -1;

140 }

141 //

142 msize=s3c2440_leds_drv_data.ledres->end-s3c2440_leds_drv_data.ledres->start+1;

143 //向内核申请资源

144 s3c2440_leds_drv_data.ledres=request_mem_region(

145 s3c2440_leds_drv_data.ledres->start,msize,DEVICE_NAME);

146 if(!s3c2440_leds_drv_data.ledres)

147 {

148 printk("request resource errorn");

149 return -1;

150 }

151

152 s3c2440_leds_drv_data.vr_gpioreg=ioremap_nocache(

153 s3c2440_leds_drv_data.ledres->start,msize);

154 if(!s3c2440_leds_drv_data.vr_gpioreg)

155 {

156 printk("ioremap_nocache errorn");

157 release_region( s3c2440_leds_drv_data.ledres->start,msize);

158 return -1;

159 }

160 memset( s3c2440_leds_drv_data.vr_gpioreg,0,sizeof(struct gpioreg));

161 //申请设备号

162 val=alloc_chrdev_region(&s3c2440_leds_drv_data.dev_nr,0,1,DEVICE_NAME);

文章来源于:电子工程世界原文链接

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