[v2,3/7] leds: add driver for LEDs from qnap-mcu devices

This adds a driver that connects to the qnap-mcu mfd driver and provides
access to the LEDs on it.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
---
 MAINTAINERS                  |   1 +
 drivers/leds/Kconfig         |  11 ++
 drivers/leds/Makefile        |   1 +
 drivers/leds/leds-qnap-mcu.c | 247 +++++++++++++++++++++++++++++++++++
 4 files changed, 260 insertions(+)
 create mode 100644 drivers/leds/leds-qnap-mcu.c

Hello Heiko,

> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index effdfc6f1e951..27eb6cd827610 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -77,6 +77,7 @@ obj-$(CONFIG_LEDS_PCA995X)		+= leds-pca995x.o
>  obj-$(CONFIG_LEDS_PM8058)		+= leds-pm8058.o
>  obj-$(CONFIG_LEDS_POWERNV)		+= leds-powernv.o
>  obj-$(CONFIG_LEDS_PWM)			+= leds-pwm.o
> +obj-$(CONFIG_LEDS_QNAP_MCU)		+= leds-qnap-mcu.o
>  obj-$(CONFIG_LEDS_REGULATOR)		+= leds-regulator.o
>  obj-$(CONFIG_LEDS_SC27XX_BLTC)		+= leds-sc27xx-bltc.o
>  obj-$(CONFIG_LEDS_SUN50I_A100)		+= leds-sun50i-a100.o
> diff --git a/drivers/leds/leds-qnap-mcu.c 
> b/drivers/leds/leds-qnap-mcu.c
> new file mode 100644
> index 0000000000000..e3244923759d2
> --- /dev/null
> +++ b/drivers/leds/leds-qnap-mcu.c
> @@ -0,0 +1,247 @@
> +// SPDX-License-Identifier: GPL-2.0-only
> +
> +/*
> + * Driver for LEDs found on QNAP MCU devices
> + *
> + * Copyright (C) 2024 Heiko Stuebner <heiko@sntech.de>
> + */
> +
> +#include <linux/leds.h>
> +#include <linux/mfd/qnap-mcu.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <uapi/linux/uleds.h>
> +
> +enum qnap_mcu_err_led_mode {
> +	QNAP_MCU_ERR_LED_ON = 0,
> +	QNAP_MCU_ERR_LED_OFF = 1,
> +	QNAP_MCU_ERR_LED_BLINK_FAST = 2,
> +	QNAP_MCU_ERR_LED_BLINK_SLOW = 3,
> +};
> +
> +struct qnap_mcu_err_led {
> +	struct qnap_mcu *mcu;
> +	struct led_classdev cdev;
> +	u8 num;
> +	u8 mode;
> +};
> +
> +static inline struct qnap_mcu_err_led *
> +		cdev_to_qnap_mcu_err_led(struct led_classdev *led_cdev)
> +{
> +	return container_of(led_cdev, struct qnap_mcu_err_led, cdev);
> +}
> +
> +static int qnap_mcu_err_led_set(struct led_classdev *led_cdev,
> +				enum led_brightness value)
> +{
> +	struct qnap_mcu_err_led *err_led = 
> cdev_to_qnap_mcu_err_led(led_cdev);
> +	u8 cmd[] = {
> +		[0] = 0x40,
> +		[1] = 0x52,
> +		[2] = 0x30 + err_led->num,
> +		[3] = 0x30
> +	};
> +
> +	/*
> +	 * If the led is off, turn it on. Otherwise don't disturb
> +	 * a possible set blink-mode.
> +	 */
> +	if (value == 0)
> +		err_led->mode = QNAP_MCU_ERR_LED_OFF;
> +	else if (err_led->mode == QNAP_MCU_ERR_LED_OFF)
> +		err_led->mode = QNAP_MCU_ERR_LED_ON;
> +
> +	cmd[3] = 0x30 + err_led->mode;
> +
> +	return qnap_mcu_exec_with_ack(err_led->mcu, cmd, sizeof(cmd));
> +}
> +
> +static int qnap_mcu_err_led_blink_set(struct led_classdev *led_cdev,
> +				      unsigned long *delay_on,
> +				      unsigned long *delay_off)
> +{
> +	struct qnap_mcu_err_led *err_led = 
> cdev_to_qnap_mcu_err_led(led_cdev);
> +	u8 cmd[] = {
> +		[0] = 0x40,
> +		[1] = 0x52,
> +		[2] = 0x30 + err_led->num,
> +		[3] = 0x30
> +	};
> +
> +	/* LED is off, nothing to do */
> +	if (err_led->mode == QNAP_MCU_ERR_LED_OFF)
> +		return 0;
> +
> +	if (*delay_on < 500) {
> +		*delay_on = 100;
> +		*delay_off = 100;
> +		err_led->mode = QNAP_MCU_ERR_LED_BLINK_FAST;
> +	} else {
> +		*delay_on = 500;
> +		*delay_off = 500;
> +		err_led->mode = QNAP_MCU_ERR_LED_BLINK_SLOW;
> +	}
> +
> +	cmd[3] = 0x30 + err_led->mode;
> +
> +	return qnap_mcu_exec_with_ack(err_led->mcu, cmd, sizeof(cmd));
> +}
> +
> +static int qnap_mcu_register_err_led(struct device *dev, struct
> qnap_mcu *mcu, int num)
> +{
> +	struct qnap_mcu_err_led *err_led;
> +	char tmp_buf[LED_MAX_NAME_SIZE];
> +	int ret;
> +
> +	err_led = devm_kzalloc(dev, sizeof(*err_led), GFP_KERNEL);
> +	if (!err_led)
> +		return -ENOMEM;
> +
> +	err_led->mcu = mcu;
> +	err_led->num = num;
> +	err_led->mode = QNAP_MCU_ERR_LED_OFF;
> +
> +	snprintf(tmp_buf, LED_MAX_NAME_SIZE, "hdd%d:red:status", num + 1);
> +	err_led->cdev.name = tmp_buf;

Should not the memory have to be allocated here via 'kzalloc' for 
'err_led->cdev.name'?
After leaving the function, tmp_buf is no longer on the stack?


> +
> +	err_led->cdev.brightness_set_blocking = qnap_mcu_err_led_set;
> +	err_led->cdev.blink_set = qnap_mcu_err_led_blink_set;
> +	err_led->cdev.brightness = 0;
> +	err_led->cdev.max_brightness = 1;
> +
> +	ret = devm_led_classdev_register(dev, &err_led->cdev);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to register hdd led %d", 
> num);
> +
> +	return qnap_mcu_err_led_set(&err_led->cdev, 0);
> +}
> +
> +enum qnap_mcu_usb_led_mode {
> +	QNAP_MCU_USB_LED_ON = 1,
> +	QNAP_MCU_USB_LED_OFF = 3,
> +	QNAP_MCU_USB_LED_BLINK = 2,
> +};
> +
> +struct qnap_mcu_usb_led {
> +	struct qnap_mcu *mcu;
> +	struct led_classdev cdev;
> +	u8 mode;
> +};
> +
> +static inline struct qnap_mcu_usb_led *
> +		cdev_to_qnap_mcu_usb_led(struct led_classdev *led_cdev)
> +{
> +	return container_of(led_cdev, struct qnap_mcu_usb_led, cdev);
> +}
> +
> +static int qnap_mcu_usb_led_set(struct led_classdev *led_cdev,
> +				enum led_brightness value)
> +{
> +	struct qnap_mcu_usb_led *usb_led = 
> cdev_to_qnap_mcu_usb_led(led_cdev);
> +	u8 cmd[] = {
> +		[0] = 0x40,
> +		[1] = 0x43,
> +		[2] = 0
> +	};
> +
> +	/*
> +	 * If the led is off, turn it on. Otherwise don't disturb
> +	 * a possible set blink-mode.
> +	 */
> +	if (value == 0)
> +		usb_led->mode = QNAP_MCU_USB_LED_OFF;
> +	else if (usb_led->mode == QNAP_MCU_USB_LED_OFF)
> +		usb_led->mode = QNAP_MCU_USB_LED_ON;
> +
> +	/* byte 3 is shared between the usb led target and setting the mode 
> */
> +	cmd[2] = 0x44 | usb_led->mode;
> +
> +	return qnap_mcu_exec_with_ack(usb_led->mcu, cmd, sizeof(cmd));
> +}
> +
> +static int qnap_mcu_usb_led_blink_set(struct led_classdev *led_cdev,
> +				      unsigned long *delay_on,
> +				      unsigned long *delay_off)
> +{
> +	struct qnap_mcu_usb_led *usb_led = 
> cdev_to_qnap_mcu_usb_led(led_cdev);
> +	u8 cmd[] = {
> +		[0] = 0x40,
> +		[1] = 0x43,
> +		[2] = 0
> +	};
> +
> +	/* LED is off, nothing to do */
> +	if (usb_led->mode == QNAP_MCU_USB_LED_OFF)
> +		return 0;
> +
> +	*delay_on = 250;
> +	*delay_off = 250;
> +	usb_led->mode = QNAP_MCU_USB_LED_BLINK;
> +
> +	/* byte 3 is shared between the usb led target and setting the mode 
> */
> +	cmd[2] = 0x44 | usb_led->mode;
> +
> +	return qnap_mcu_exec_with_ack(usb_led->mcu, cmd, sizeof(cmd));
> +}
> +
> +static int qnap_mcu_register_usb_led(struct device *dev, struct 
> qnap_mcu *mcu)
> +{
> +	struct qnap_mcu_usb_led *usb_led;
> +	int ret;
> +
> +	usb_led = devm_kzalloc(dev, sizeof(*usb_led), GFP_KERNEL);
> +	if (!usb_led)
> +		return -ENOMEM;
> +
> +	usb_led->mcu = mcu;
> +	usb_led->mode = QNAP_MCU_USB_LED_OFF;
> +	usb_led->cdev.name = "usb:blue:disk";
> +	usb_led->cdev.brightness_set_blocking = qnap_mcu_usb_led_set;
> +	usb_led->cdev.blink_set = qnap_mcu_usb_led_blink_set;
> +	usb_led->cdev.brightness = 0;
> +	usb_led->cdev.max_brightness = 1;
> +
> +	ret = devm_led_classdev_register(dev, &usb_led->cdev);
> +	if (ret)
> +		return dev_err_probe(dev, ret, "failed to register usb led");
> +
> +	return qnap_mcu_usb_led_set(&usb_led->cdev, 0);
> +}
> +
> +static int qnap_mcu_leds_probe(struct platform_device *pdev)
> +{
> +	struct qnap_mcu *mcu = dev_get_drvdata(pdev->dev.parent);
> +	const struct qnap_mcu_variant *variant = 
> qnap_mcu_get_variant_data(mcu);
> +	int ret, i;
> +
> +	for (i = 0; i < variant->num_drives; i++) {
> +		ret = qnap_mcu_register_err_led(&pdev->dev, mcu, i);
> +		if (ret)
> +			return dev_err_probe(&pdev->dev, ret,
> +					"failed to register error led %d\n", i);
> +	}
> +
> +	if (variant->usb_led) {
> +		ret = qnap_mcu_register_usb_led(&pdev->dev, mcu);
> +		if (ret)
> +			return dev_err_probe(&pdev->dev, ret,
> +					"failed to register usb led %d\n", i);
> +	}
> +
> +	return 0;
> +}
> +
> +static struct platform_driver qnap_mcu_leds_driver = {
> +	.probe = qnap_mcu_leds_probe,
> +	.driver = {
> +		.name = "qnap-mcu-leds",
> +	},
> +};
> +module_platform_driver(qnap_mcu_leds_driver);
> +
> +MODULE_ALIAS("platform:qnap-mcu-leds");
> +MODULE_AUTHOR("Heiko Stuebner <heiko@sntech.de>");
> +MODULE_DESCRIPTION("QNAP MCU LEDs driver");
> +MODULE_LICENSE("GPL");

Hi Florian,

Am Montag, 29. Juli 2024, 08:24:26 CEST schrieb Florian Eckert:
> > +static int qnap_mcu_register_err_led(struct device *dev, struct
> > qnap_mcu *mcu, int num)
> > +{
> > +	struct qnap_mcu_err_led *err_led;
> > +	char tmp_buf[LED_MAX_NAME_SIZE];
> > +	int ret;
> > +
> > +	err_led = devm_kzalloc(dev, sizeof(*err_led), GFP_KERNEL);
> > +	if (!err_led)
> > +		return -ENOMEM;
> > +
> > +	err_led->mcu = mcu;
> > +	err_led->num = num;
> > +	err_led->mode = QNAP_MCU_ERR_LED_OFF;
> > +
> > +	snprintf(tmp_buf, LED_MAX_NAME_SIZE, "hdd%d:red:status", num + 1);
> > +	err_led->cdev.name = tmp_buf;
> 
> Should not the memory have to be allocated here via 'kzalloc' for 
> 'err_led->cdev.name'?
> After leaving the function, tmp_buf is no longer on the stack?

Reading the led_classdev_register thing, cdev->name is used only for
creating the final-name for the LED and thus copied into yet another
temporary buffer [0] .

And cdev->name is not accessed anymore outside the register function.

But thinking more about that, you're still right, because after registering
cdev->name is in a bad state, pointing to something no valid anymore.
So if the LED core changes behaviour in the future, this will cause breakage.

So I'll change that.


Thanks for catching that
Heiko



[0] https://elixir.bootlin.com/linux/v6.10.1/source/drivers/leds/led-class.c#L500
https://elixir.bootlin.com/linux/v6.10.1/source/drivers/leds/led-class.c#L503