linux platform 总线（设备树）驱动

使用文档

设备树修改

新增一个 LED 节点 arch/arm/boot/dts/arm/vexpress-v2p-ca9.dts

	my_pl_led {compatible = "arm, cortex-a9-led";status = "okay";};

设备树编译

make dtbs

日志

  DTC     arch/arm/boot/dts/arm/vexpress-v2p-ca9.dtb

platform driver 源码

#include "linux/export.h"
#include "linux/ioport.h"
#include <linux/fs.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/types.h>
#include <linux/mod_devicetable.h>
#include <linux/of.h>#define PLATFORM_DEVICE_NAME "my_pl_led" /* 匹配设备树节点的名字 */static int my_probe(struct platform_device *device)
{printk("platform driver probe\r\n");struct device_node *my_device_node;my_device_node = of_find_node_by_name(NULL, PLATFORM_DEVICE_NAME);if (my_device_node) {printk("device node name %s \r\n", my_device_node->name);/* 获取  compatible 属性的字符串。*/const char *compatible;compatible = of_get_property(my_device_node, "compatible", NULL);if (compatible) {printk("Compatible property: %s\n", compatible);} else {printk("Compatible property not found\n");}/* 获取  status 属性的字符串。*/compatible = of_get_property(my_device_node, "status", NULL);if (compatible) {printk("status property: %s\n", compatible);} else {printk("status property not found\n");}} else {printk("can't find device node\r\n");}return 0;
}static int my_remove(struct platform_device *device)
{printk("platform driver remove\r\n");return 0;
}/*** @brief include mod_devicetable.h. 传统匹配方式ID列表* */
static const struct platform_device_id test_id_table = {.name = "low pri name", /* 用于非设备树匹配的时候，如果有设备树，可以匹配 compatible 属性的名字。 */
};/* 匹配列表 */
static const struct of_device_id led_of_match[] = {{ .compatible = "arm, cortex-a9-led" }, /* 和设备树节点 compatible 匹配的名字 */{ /* Sentinel */ },
};static struct platform_driver platform_driver_test = {.probe = my_probe,.remove = my_remove,.driver = {.of_match_table = led_of_match, /* 设备树匹配机制，匹配设备树中的 compatible 属性，优先级高 */.name = "my_pl_driver", /* platform 驱动名(ls /sys/bus/platform/drivers/my_pl_driver/) */.owner = THIS_MODULE,},.id_table   = &test_id_table, /* 旧的匹配机制，优先级低 */
};static int __init platform_driver_init(void)
{platform_driver_register(&platform_driver_test);printk("k: platform driver module init!\r\n");return 0;
}static void __exit platform_driver_exit(void)
{platform_driver_unregister(&platform_driver_test);printk("k: platform driver module exit!\r\n");
}module_init(platform_driver_init);
module_exit(platform_driver_exit);MODULE_LICENSE("GPL");
MODULE_AUTHOR("tyustli");
MODULE_INFO(intree, "Y"); /* loading out-of-tree module taints kernel */

makefile 源码

# 指定内核路径
KERNELDIR := /home/tyustli/code/open_source/kernel/linux-6.5.7
# 指定当前路径
CURRENT_PATH := $(shell pwd)
# 指定编译的模块名
obj-m := my_platform_driver.obuild: kernel_moduleskernel_modules:$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) modules
clean:$(MAKE) -C $(KERNELDIR) M=$(CURRENT_PATH) clean

编译驱动

../my_module_build.sh ../0013_dtsplatform/

查看模块 ko 文件

ls /lib/modules/6.5.7+/
my_platform_driver.ko

查看 platform 设备

ls /sys/bus/platform/devices/my_pl_led/
driver_override       power                 waiting_for_supplier
modalias              subsystem
of_node               uevent

platform 驱动

如果编译报错

 error: ‘const struct platform_device_id’ has no member named ‘name’

解决

#include <linux/mod_devicetable.h>

platform_device_id 结构体原型

struct platform_device_id {char name[PLATFORM_NAME_SIZE];kernel_ulong_t driver_data;
};

platform 驱动模块安装

modprobe my_platform_driver

匹配成功日志

platform driver probe
device node name my_pl_led 
Compatible property: arm, cortex-a9-led
status property: okay
k: platform driver module init!
drm-clcd-pl111 10020000.clcd: DVI muxed to daughterboard 1 (core tile) CLCD
drm-clcd-pl111 10020000.clcd: initializing Versatile Express PL111

查看 platform 驱动

ls /sys/bus/platform/drivers/my_pl_driver/
bind    module  uevent  unbind

退出

Ctrl + a
x

注意事项

static struct platform_driver platform_driver_test = {.probe = my_probe,.remove = my_remove,.driver = {.of_match_table = led_of_match, /* 设备树匹配机制，匹配设备树中的 compatible 属性，优先级高 */.name = "my_pl_driver", /* platform 驱动名(ls /sys/bus/platform/drivers/my_pl_driver/) */.owner = THIS_MODULE,},.id_table   = &test_id_table, /* 旧的匹配机制，优先级低 */
};