[话题]

【NanoPC-T4试用体验】3、点亮一盏LED( 下)

2018-10-24 21:32:57 6091

0 `本系列帖子是为试用Nano PC T4开发板的帖子连载篇，以下为目录：【NanoPC-T4试用体验】1、Nano PC T4开箱上电【NanoPC-T4试用体验】2、点亮一盏LED 【NanoPC-T4试用体验】3、点亮一盏LED( 下) 接上文，由于上一篇文章篇幅过长，以及编辑器的各种BUG，导致后半部分的一直没有发送成功，现在特地补一下，前面提到，我们已经搭建好了开发以及LED设备树的添加。回顾一下，LED的设备树添加如下： myleds: mygpio-leds { compatible = "mygpio-leds"; pinctrl-names = "default"; pinctrl-0 =<&myleds_gpio>; led@1 { gpios = <&gpio1 0 GPIO_ACTIVE_HIGH>; label = "my_led"; linux,default-trigger = "heartbeat"; linux,default-trigger-delay-ms = <0>; }; }; mygpio-leds { myleds_gpio: myleds-gpio { rockchip,pins = <1 0 RK_FUNC_GPIO &pcfg_pull_none>; }; }; 复制代码驱动代码主要参考了内核中提供的代码： #include #include #include #include #include #include #include #include #include #include #include struct gpio_led_data { struct led_classdev cdev; struct gpio_desc gpiod; struct work_struct work; u8 new_level; u8 can_sleep; u8 blinking; int (platform_gpio_blink_set)(struct gpio_desc desc, int state, unsigned long delay_on, unsigned long delay_off); }; static void gpio_led_work(struct work_struct work) { struct gpio_led_data led_dat = container_of(work, struct gpio_led_data, work); if (led_dat->blinking) { led_dat->platform_gpio_blink_set(led_dat->gpiod, led_dat->new_level, NULL, NULL); led_dat->blinking = 0; } else gpiod_set_value_cansleep(led_dat->gpiod, led_dat->new_level); } static void gpio_led_set(struct led_classdev led_cdev, enum led_brightness value) { struct gpio_led_data led_dat = container_of(led_cdev, struct gpio_led_data, cdev); int level; if (value == LED_OFF) level = 0; else level = 1; / Setting GPIOs with I2C/etc requires a task context, and we don't * seem to have a reliable way to know if we're already in one; so * let's just assume the worst. / if (led_dat->can_sleep) { led_dat->new_level = level; schedule_work(&led_dat->work); } else { if (led_dat->blinking) { led_dat->platform_gpio_blink_set(led_dat->gpiod, level, NULL, NULL); led_dat->blinking = 0; } else gpiod_set_value(led_dat->gpiod, level); } } static int gpio_blink_set(struct led_classdev led_cdev, unsigned long delay_on, unsigned long delay_off) { struct gpio_led_data led_dat = container_of(led_cdev, struct gpio_led_data, cdev); led_dat->blinking = 1; return led_dat->platform_gpio_blink_set(led_dat->gpiod, GPIO_LED_BLINK, delay_on, delay_off); } static int create_gpio_led(const struct gpio_led template, struct gpio_led_data led_dat, struct device parent, int (blink_set)(struct gpio_desc , int, unsigned long , unsigned long )) { int ret, state; led_dat->gpiod = template->gpiod; if (!led_dat->gpiod) { /* * This is the legacy code path for platform code that * still uses GPIO numbers. Ultimately we would like to get * rid of this block completely. / unsigned long flags = 0; / skip leds that aren't available / if (!gpio_is_valid(template->gpio)) { dev_info(parent, "Skipping unavailable LED gpio %d (%s) ", template->gpio, template->name); return 0; } if (template->active_low) flags \|= GPIOF_ACTIVE_LOW; ret = devm_gpio_request_one(parent, template->gpio, flags, template->name); if (ret < 0) return ret; led_dat->gpiod = gpio_to_desc(template->gpio); if (IS_ERR(led_dat->gpiod)) return PTR_ERR(led_dat->gpiod); } led_dat->cdev.name = template->name; led_dat->cdev.default_trigger = template->default_trigger; led_dat->can_sleep = gpiod_cansleep(led_dat->gpiod); led_dat->blinking = 0; if (blink_set) { led_dat->platform_gpio_blink_set = blink_set; led_dat->cdev.blink_set = gpio_blink_set; } led_dat->cdev.brightness_set = gpio_led_set; if (template->default_state == LEDS_GPIO_DEFSTATE_KEEP) state = !!gpiod_get_value_cansleep(led_dat->gpiod); else state = (template->default_state == LEDS_GPIO_DEFSTATE_ON); led_dat->cdev.brightness = state ? LED_FULL : LED_OFF; if (!template->retain_state_suspended) led_dat->cdev.flags \|= LED_CORE_SUSPENDRESUME; ret = gpiod_direction_output(led_dat->gpiod, state); if (ret < 0) return ret; INIT_WORK(&led_dat->work, gpio_led_work); return led_classdev_register(parent, &led_dat->cdev); } static void delete_gpio_led(struct gpio_led_data led) { led_classdev_unregister(&led->cdev); cancel_work_sync(&led->work); } struct gpio_leds_priv { int num_leds; struct gpio_led_data leds[]; }; static inline int sizeof_gpio_leds_priv(int num_leds) { return sizeof(struct gpio_leds_priv) + (sizeof(struct gpio_led_data) * num_leds); } static struct gpio_leds_priv gpio_leds_create(struct platform_device pdev) { struct device dev = &pdev->dev; struct fwnode_handle child; struct gpio_leds_priv priv; int count, ret; struct device_node np; count = device_get_child_node_count(dev); if (!count) return ERR_PTR(-ENODEV); priv = devm_kzalloc(dev, sizeof_gpio_leds_priv(count), GFP_KERNEL); if (!priv) return ERR_PTR(-ENOMEM); device_for_each_child_node(dev, child) { struct gpio_led led = {}; const char state = NULL; led.gpiod = devm_get_gpiod_from_child(dev, NULL, child); if (IS_ERR(led.gpiod)) { fwnode_handle_put(child); ret = PTR_ERR(led.gpiod); goto err; } np = to_of_node(child); if (fwnode_property_present(child, "label")) { fwnode_property_read_string(child, "label", &led.name); } else { if (IS_ENABLED(CONFIG_OF) && !led.name && np) led.name = np->name; if (!led.name) { ret = -EINVAL; goto err; } } fwnode_property_read_string(child, "linux,default-trigger", &led.default_trigger); if (!fwnode_property_read_string(child, "default-state", &state)) { if (!strcmp(state, "keep")) led.default_state = LEDS_GPIO_DEFSTATE_KEEP; else if (!strcmp(state, "on")) led.default_state = LEDS_GPIO_DEFSTATE_ON; else led.default_state = LEDS_GPIO_DEFSTATE_OFF; } if (fwnode_property_present(child, "retain-state-suspended")) led.retain_state_suspended = 1; ret = create_gpio_led(&led, &priv->leds[priv->num_leds], dev, NULL); if (ret < 0) { fwnode_handle_put(child); goto err; } priv->num_leds++; } return priv; err: for (count = priv->num_leds - 1; count >= 0; count--) delete_gpio_led(&priv->leds[count]); return ERR_PTR(ret); } static const struct of_device_id of_gpio_leds_match[] = { { .compatible = "mygpio-leds", }, {}, }; MODULE_DEVICE_TABLE(of, of_gpio_leds_match); static int gpio_led_probe(struct platform_device pdev) { struct gpio_led_platform_data pdata = dev_get_platdata(&pdev->dev); struct gpio_leds_priv priv; int i, ret = 0; if (pdata && pdata->num_leds) { priv = devm_kzalloc(&pdev->dev, sizeof_gpio_leds_priv(pdata->num_leds), GFP_KERNEL); if (!priv) return -ENOMEM; priv->num_leds = pdata->num_leds; for (i = 0; i < priv->num_leds; i++) { ret = create_gpio_led(&pdata->leds, &priv->leds, &pdev->dev, pdata->gpio_blink_set); if (ret < 0) { /* On failure: unwind the led creations / for (i = i - 1; i >= 0; i--) delete_gpio_led(&priv->leds); return ret; } } } else { priv = gpio_leds_create(pdev); if (IS_ERR(priv)) return PTR_ERR(priv); } platform_set_drvdata(pdev, priv); return 0; } static int gpio_led_remove(struct platform_device pdev) { struct gpio_leds_priv priv = platform_get_drvdata(pdev); int i; for (i = 0; i < priv->num_leds; i++) delete_gpio_led(&priv->leds); return 0; } static void gpio_led_shutdown(struct platform_device pdev) { struct gpio_leds_priv priv = platform_get_drvdata(pdev); int i; for (i = 0; i < priv->num_leds; i++) { struct gpio_led_data led = &priv->leds; gpio_led_set(&led->cdev, LED_OFF); } } static struct platform_driver gpio_led_driver = { .probe = gpio_led_probe, .remove = gpio_led_remove, .shutdown = gpio_led_shutdown, .driver = { .name = "myleds-gpio", .of_match_table = of_gpio_leds_match, }, }; module_platform_driver(gpio_led_driver); MODULE_DESCRIPTION("GPIO LED driver"); MODULE_LICENSE("GPL"); MODULE_ALIAS("platform:myleds-gpio"); 使用的makefile如下： ROOTFS_DIR = /home/pi/ ifeq ($(KERNELRELEASE), ) KERNEL_DIR = /home/pi/t4_develop/t4_kernel CUR_DIR = $(shell pwd) all : make -C $(KERNEL_DIR) M=$(CUR_DIR) modules clean : make -C $(KERNEL_DIR) M=$(CUR_DIR) clean install: cp -raf .ko $(ROOTFS_DIR) else obj-m += leds-gpio.o #obj-m += math.o endif 复制代码* 内核的地址如下： KERNEL_DIR = /home/pi/t4_develop/t4_kernel 由于我们是在板子上直接编译的，所以我们直接编译，然后安装即可。 make insmod leds-gpio.ko 复制代码安装成功，我们可以使用 lsmod指令确认一下：接下来，我们来看一下，驱动加载进去与否：可以看到，已经将设备树与驱动匹配成功了！最终效果： ` 0
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