因为项目需要控制的GPIO口比较多，如果每个GPIO口都写一个驱动就显得比骄麻烦，所以就写了一个通用的GPIO口驱动。只要dts里面配置好设备GPIO相关信息就可以自动加载了。可以很充分的体现多个设备一个驱动的优良性。

dts文件

    gpio_rs485: gpio_rs485 {status = "okay";compatible = "gpio,px30-gpio";cname = "rs485";en-gpio = <&gpio3 12 GPIO_ACTIVE_HIGH>;};

驱动源代码

#include <dt-bindings/gpio/gpio.h>
#include <linux/gpio.h>
#include <linux/of_gpio.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/slab.h>struct gpio_dev_data {int en_pin;int en_val;int gpio_val;
};static struct of_device_id gpio_of_match[] = {{ .compatible = "gpio,px30-gpio" },{ }
};MODULE_DEVICE_TABLE(of, gpio_of_match);static ssize_t gpio_store_en(struct device *dev,struct device_attribute *attr,const char *buf, size_t count)
{struct gpio_dev_data *dev_data = dev_get_drvdata(dev);unsigned long value = 0;int ret;/*将echo进来的buf转换成整型*/ret = kstrtoul(buf, 16, &value);if (ret < 0) {printk( "%s:kstrtoul failed, ret=%d\n", __func__, ret);return ret;}printk("%s: en value : %d\n", __func__, (int)value);if (value) {gpio_direction_output(dev_data->en_pin, dev_data->en_val);dev_data->gpio_val = 1;} else {gpio_direction_output(dev_data->en_pin, !dev_data->en_val);dev_data->gpio_val = 0;}return count;
}static  char mybuf[10]="123";/*cat命令时,将会调用该函数*/
static ssize_t gpio_show_en(struct device *dev,struct device_attribute *attr, char *buf)
{struct gpio_dev_data *dev_data = dev_get_drvdata(dev);snprintf(mybuf,sizeof(mybuf),"%d",dev_data->gpio_val);return sprintf(buf, "%s\n", mybuf);
}static DEVICE_ATTR(gpio_en, S_IWUSR, gpio_show_en, gpio_store_en);static int gpio_probe(struct platform_device *pdev)
{struct device_node *node = pdev->dev.of_node;enum of_gpio_flags flags;int gpio;int ret;int en_value;struct class *dev_class;struct device *ctl_dev;struct gpio_dev_data *dev_data;int err;const char *class_name;printk("%s enter: %d\n", __func__, __LINE__);if (!node)return -ENODEV;/*获取gpio口*/gpio = of_get_named_gpio_flags(node, "en-gpio", 0, &flags);en_value = (flags == GPIO_ACTIVE_HIGH) ? 1 : 0;if (!gpio_is_valid(gpio)) {dev_err(&pdev->dev, "invalid en gpio%d\n", gpio);}ret = devm_gpio_request(&pdev->dev, gpio, "onoff");if (ret) {dev_err(&pdev->dev,"failed to request GPIO%d for \n",gpio);return -EINVAL;}/*设置probe的默认电平*/gpio_direction_output(gpio, !en_value);dev_data = kzalloc(sizeof(struct gpio_dev_data), GFP_KERNEL);if (dev_data == NULL) {printk("Failed to malloc gpio_dev_data\n");return -ENOMEM;}if(en_value > 0)dev_data->gpio_val = 0;elsedev_data->gpio_val = 1;/*创建class节点*/err = of_property_read_string(node, "cname", &class_name);if(err){printk("%s get class name error %d\n",__FUNCTION__,__LINE__);return -EINVAL;}dev_class = class_create(THIS_MODULE, class_name);ctl_dev = device_create(dev_class, NULL, 0, NULL, "onoff");if (IS_ERR(ctl_dev)) {dev_err(ctl_dev, "Failed to create device\n");ret = PTR_ERR(ctl_dev);goto err_create_dev;}err = device_create_file(ctl_dev, &dev_attr_gpio_en);if (err)printk("driver_create_file = %d\n", err);/*获取的gpio赋值全局变量*/dev_data->en_pin = gpio;dev_data->en_val = en_value;dev_info(ctl_dev, "%s: %d\n", __func__, __LINE__);dev_info(&pdev->dev, "%s: %d\n", __func__, __LINE__);dev_set_drvdata(ctl_dev, dev_data);dev_set_drvdata(&pdev->dev, dev_data);return 0;err_create_dev:kfree(dev_data);return ret;
}static int gpio_remove(struct platform_device *pdev)
{printk("%s: %d\n", __func__, __LINE__);return 0;
}#ifdef CONFIG_PM_SLEEP
static int gpio_suspend(struct device *dev)
{struct gpio_dev_data *dev_data = dev_get_drvdata(dev);dev_info(dev, "%s: %d\n", __func__, __LINE__);gpio_direction_output(dev_data->en_pin, !dev_data->en_val);return 0;
}static int gpio_resume(struct device *dev)
{printk("%s: %d\n", __func__, __LINE__);return 0;
}
#endifstatic const struct dev_pm_ops gpio_pm_ops = {
#ifdef CONFIG_PM_SLEEP.suspend = gpio_suspend,.resume = gpio_resume,.poweroff = gpio_suspend,.restore = gpio_resume,
#endif
};static struct platform_driver gpio_driver = {.driver     = {.name   = "gpio-en",.owner   = THIS_MODULE,.pm      = &gpio_pm_ops,.of_match_table = of_match_ptr(gpio_of_match),},.probe     = gpio_probe,.remove       = gpio_remove,
};module_platform_driver(gpio_driver);MODULE_AUTHOR("Weiqifa <329410527@qq.com>");
MODULE_DESCRIPTION("simple gpio driver");
MODULE_LICENSE("GPL");

Makefile文件

obj-$(CONFIG_GPIO_CONTROL) += gpio_control.o

Kconfig

config GPIO_CONTROLtristate "GPIO control driver"default nhelpGPIO control driver.

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