drivers/gpu/drm/nouveau/nouveau_led.c

Source file repositories/reference/linux-study-clean/drivers/gpu/drm/nouveau/nouveau_led.c

File Facts

System
Linux kernel
Corpus path
drivers/gpu/drm/nouveau/nouveau_led.c
Extension
.c
Size
3876 bytes
Lines
141
Domain
Driver Families
Bucket
drivers/gpu
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

#include <linux/leds.h>

#include "nouveau_led.h"
#include <nvkm/subdev/gpio.h>

static enum led_brightness
nouveau_led_get_brightness(struct led_classdev *led)
{
	struct drm_device *drm_dev = container_of(led, struct nouveau_led, led)->dev;
	struct nouveau_drm *drm = nouveau_drm(drm_dev);
	struct nvif_object *device = &drm->client.device.object;
	u32 div, duty;

	div =  nvif_rd32(device, 0x61c880) & 0x00ffffff;
	duty = nvif_rd32(device, 0x61c884) & 0x00ffffff;

	if (div > 0)
		return duty * LED_FULL / div;
	else
		return 0;
}

static void
nouveau_led_set_brightness(struct led_classdev *led, enum led_brightness value)
{
	struct drm_device *drm_dev = container_of(led, struct nouveau_led, led)->dev;
	struct nouveau_drm *drm = nouveau_drm(drm_dev);
	struct nvif_object *device = &drm->client.device.object;

	u32 input_clk = 27e6; /* PDISPLAY.SOR[1].PWM is connected to the crystal */
	u32 freq = 100; /* this is what nvidia uses and it should be good-enough */
	u32 div, duty;

	div = input_clk / freq;
	duty = value * div / LED_FULL;

	/* for now, this is safe to directly poke those registers because:
	 *  - A: nvidia never puts the logo led to any other PWM controler
	 *       than PDISPLAY.SOR[1].PWM.
	 *  - B: nouveau does not touch these registers anywhere else
	 */
	nvif_wr32(device, 0x61c880, div);
	nvif_wr32(device, 0x61c884, 0xc0000000 | duty);
}


int
nouveau_led_init(struct drm_device *dev)
{
	struct nouveau_drm *drm = nouveau_drm(dev);
	struct nvkm_gpio *gpio = nvxx_gpio(drm);
	struct dcb_gpio_func logo_led;
	int ret;

	if (!gpio)
		return 0;

	/* check that there is a GPIO controlling the logo LED */
	if (nvkm_gpio_find(gpio, 0, DCB_GPIO_LOGO_LED_PWM, 0xff, &logo_led))
		return 0;

	drm->led = kzalloc_obj(*drm->led);
	if (!drm->led)
		return -ENOMEM;
	drm->led->dev = dev;

	drm->led->led.name = "nvidia-logo";
	drm->led->led.max_brightness = 255;
	drm->led->led.brightness_get = nouveau_led_get_brightness;
	drm->led->led.brightness_set = nouveau_led_set_brightness;

	ret = led_classdev_register(dev->dev, &drm->led->led);
	if (ret) {
		kfree(drm->led);
		drm->led = NULL;
		return ret;
	}

	return 0;
}

void
nouveau_led_suspend(struct drm_device *dev)
{
	struct nouveau_drm *drm = nouveau_drm(dev);

	if (drm->led)
		led_classdev_suspend(&drm->led->led);
}

Annotation

Implementation Notes