Re: [PATCH] leds: USB: Add support for MSI GT683R led panels

[Johan Hovold <johan-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

[ +CC: linux-usb ]

On Sat, May 31, 2014 at 06:46:44PM +0300, Janne Kanniainen wrote:
> This driver adds support for USB controlled led panels that exist in MSI GT683R laptop.
> 
> Signed-off-by: Janne Kanniainen <janne.kanniainen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  drivers/leds/Kconfig       |   6 ++
>  drivers/leds/Makefile      |   1 +
>  drivers/leds/leds-gt683r.c | 241 +++++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 248 insertions(+)
>  create mode 100644 drivers/leds/leds-gt683r.c
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 6de9dfb..2cffa0c 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -487,6 +487,12 @@ config LEDS_BLINKM
>  	  This option enables support for the BlinkM RGB LED connected
>  	  through I2C. Say Y to enable support for the BlinkM LED.
>  
> +config LEDS_GT683R
> +       tristate "LED support for the MSI GT683R"
> +       depends on LEDS_CLASS && USB
> +       help
> +         This option enables support for the MSI GT683R LEDS
> +
>  comment "LED Triggers"
>  source "drivers/leds/trigger/Kconfig"
>  
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 3cd76db..af5fb4e 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -54,6 +54,7 @@ obj-$(CONFIG_LEDS_ASIC3)		+= leds-asic3.o
>  obj-$(CONFIG_LEDS_MAX8997)		+= leds-max8997.o
>  obj-$(CONFIG_LEDS_LM355x)		+= leds-lm355x.o
>  obj-$(CONFIG_LEDS_BLINKM)		+= leds-blinkm.o
> +obj-$(CONFIG_LEDS_GT683R)		+= leds-gt683r.o
>  
>  # LED SPI Drivers
>  obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
> diff --git a/drivers/leds/leds-gt683r.c b/drivers/leds/leds-gt683r.c
> new file mode 100644
> index 0000000..d67709c
> --- /dev/null
> +++ b/drivers/leds/leds-gt683r.c
> @@ -0,0 +1,241 @@
> +/*
> + * MSI GT683R led driver
> + *
> + * Copyright (c) 2014 Janne Kanniainen <janne.kanniainen-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/kernel.h>
> +#include <linux/usb.h>
> +#include <linux/slab.h>
> +#include <linux/leds.h>
> +
> +#define USB_DEVICE_ID_MSI_GT683R_LED_PANEL 0xff00
> +#define USB_VENDOR_ID_MSI 0x1770
> +
> +#define GT683R_LED_MSG_TYPE_CTRL 0
> +#define GT683R_LED_MSG_TYPE_INT 1

These two are never used.

> +
> +#define GT683R_LED_FRONT 4
> +#define GT683R_LED_SIDE 2
> +#define GT683R_LED_BACK 1

Sort and use BIT(n) for these?

> +#define GT683R_LED_NORMAL 5
> +#define GT683R_LED_BREATHING 3
> +#define GT683R_LED_AUDIO 2
> +#define GT683R_LED_OFF 0

Sort these numerically as well?

Please use tabs to align the values above as well.

> +
> +struct gt683r_led {
> +	struct usb_device *usb_dev;
> +
> +	struct usb_endpoint_descriptor *ctrl_out_ep;
> +	int ctrl_out_buffer_size;
> +	char *ctrl_out_buffer;
> +	struct usb_ctrlrequest *ctrl_out_request;
> +	struct urb *ctrl_out_urb;

You don't need to track ctrl_out_urb, which you allocate dynamically for
every message (more below).

> +
> +	struct led_classdev led_dev;
> +	struct mutex lock;
> +	struct work_struct work;
> +
> +	enum led_brightness brightness;
> +};
> +
> +static const struct usb_device_id gt683r_led_id[] = {
> +	{ USB_DEVICE(USB_VENDOR_ID_MSI, USB_DEVICE_ID_MSI_GT683R_LED_PANEL) },
> +	{ }
> +};
> +
> +static char gt683r_led_select_leds[8] = {0x01, 0x02, 0x30, 0x00,
> +					 0x00, 0x00, 0x00, 0x00};
> +static char gt683r_led_select_type[8] = {0x01, 0x02, 0x20, 0x00,
> +					 0x01, 0x00, 0x00, 0x00};

It would be better to make these const (or remove altogether) and only
modify the fourth byte of the copy (more below).

> +
> +static void gt683r_brightness_set(struct led_classdev *led_cdev,
> +				  enum led_brightness brightness)
> +{
> +	struct gt683r_led *led =
> +			container_of(led_cdev, struct gt683r_led, led_dev);
> +
> +	led->brightness = brightness;

Missing locking?

> +
> +	schedule_work(&led->work);
> +}
> +
> +static void gt683r_led_msg_snd_complete(struct urb *urb)
> +{
> +	usb_free_urb(urb);
> +}
> +
> +static int gt683r_led_snd_msg(struct gt683r_led *led, char *msg)
> +{
> +	int result;
> +
> +	if (strlen(msg) > led->ctrl_out_buffer_size) {

This is bogus. You can't use strlen on your byte arrays that contains
NULL-bytes.

If at all needed you could verify wMaxPacketSize once at probe.

> +		dev_err(&led->usb_dev->dev, "Message to be send to device is too long\n");
> +		return -EMSGSIZE;
> +	}
> +
> +	led->ctrl_out_urb = usb_alloc_urb(0, GFP_KERNEL);
> +	strcpy(led->ctrl_out_buffer, msg);

So this won't work either for the same reason.

> +	usb_fill_control_urb(led->ctrl_out_urb,
> +			     led->usb_dev,
> +			     usb_sndctrlpipe(led->usb_dev, led->ctrl_out_ep->bEndpointAddress),
> +			     (unsigned char *) led->ctrl_out_request,
> +			     led->ctrl_out_buffer,

Here you using the same buffer in two different urbs (you submit two
consecutive urbs below) that are submitted asynchronously, which is
likely to lead to buffer corruption or worse.

> +			     led->ctrl_out_buffer_size,

Why set the full buffer length when you have only filled it with 8
bytes?

> +			     gt683r_led_msg_snd_complete,
> +			     led);
> +
> +	result = usb_submit_urb(led->ctrl_out_urb, GFP_KERNEL);

Have you considered using synchronous control requests using
usb_control_msg() instead?

> +

No empty line.

> +	if (result) {
> +		dev_err(&led->usb_dev->dev, "Failed to submit urb\n");
> +		return -ECOMM;

Why not return result (if anything -- you never use the return value
below).

> +	}
> +
> +	return 0;
> +}
> +
> +static void gt683r_led_set(struct gt683r_led *led, char leds, char type)
> +{
> +	gt683r_led_select_leds[3] = leds;
> +	gt683r_led_select_type[3] = type;

Please rethink this and modify the dynamically allocated buffers before
submission instead (as mentioned above).

> +	gt683r_led_snd_msg(led, gt683r_led_select_leds);
> +	gt683r_led_snd_msg(led, gt683r_led_select_type);
> +}
> +
> +static void gt683r_led_work(struct work_struct *work)
> +{
> +	struct gt683r_led *led =
> +			container_of(work, struct gt683r_led, work);
> +
> +	mutex_lock(&led->lock);
> +
> +	if (led->brightness)
> +		gt683r_led_set(led, GT683R_LED_FRONT|GT683R_LED_SIDE|
> +			       GT683R_LED_BACK, GT683R_LED_NORMAL);
> +	else
> +		gt683r_led_set(led, GT683R_LED_FRONT|GT683R_LED_SIDE|
> +			       GT683R_LED_BACK, GT683R_LED_OFF);

Why have a leds parameter to gt683r_led_set if you always pass the same
value? You could at least clean this up using a common define or const
variable.

> +
> +	mutex_unlock(&led->lock);
> +}
> +
> +static struct led_classdev gt683r_led_dev = {
> +	.name = "gt683r-led",
> +	.brightness_set = gt683r_brightness_set,
> +	.max_brightness = 1,
> +	.flags = LED_CORE_SUSPENDRESUME,
> +};
> +
> +static int gt683r_led_probe(struct usb_interface *intf,
> +			    const struct usb_device_id *id)
> +{
> +	int ret = 0;
> +	struct usb_endpoint_descriptor *endpoint;
> +

Remove this empty line.

> +	struct gt683r_led *led = kzalloc(sizeof(struct gt683r_led), GFP_KERNEL);

Please split definition and initialisation here.

> +

I'd remove this one as well.

> +	if (!led) {
> +		ret = -ENOMEM;
> +		goto fail;
> +	}
> +
> +	led->usb_dev = interface_to_usbdev(intf);
> +	usb_set_intfdata(intf, led);
> +	endpoint = &led->usb_dev->ep0.desc;
> +
> +	if (!led->ctrl_out_ep &&

How could ctrl_out_ep ever be non-NULL at this point when you just
allocated and zeroed the led struct?

> +	    usb_endpoint_xfer_control(endpoint) &&
> +	    usb_endpoint_dir_out(endpoint)) {

And EP0 is always a bidirectional control endpoint, so this should
always evaluate to true as well?

> +		led->ctrl_out_ep = endpoint;
> +		led->ctrl_out_buffer_size = endpoint->wMaxPacketSize;

You should use usb_endpoint_maxp() to handle endianess conversion.

> +		led->ctrl_out_buffer = kmalloc(led->ctrl_out_buffer_size,
> +					       GFP_KERNEL);
> +		if (!led->ctrl_out_buffer) {
> +			ret = -ENOMEM;
> +			goto fail;
> +		}
> +		led->ctrl_out_request = kmalloc(sizeof(struct usb_ctrlrequest),
> +						     GFP_KERNEL);
> +		if (!led->ctrl_out_request) {
> +			ret = -ENOMEM;
> +			goto fail;
> +		}
> +		led->ctrl_out_request->bRequestType = 0x22;
> +		led->ctrl_out_request->bRequest = 0x09;
> +		led->ctrl_out_request->wValue = cpu_to_le16(0x0301);
> +		led->ctrl_out_request->wIndex = cpu_to_le16(0x0000);
> +		led->ctrl_out_request->wLength = cpu_to_le16(0x0008);
> +	}
> +
> +	if (!led->ctrl_out_ep) {

So this does not make sense anymore.

> +		dev_err(&led->usb_dev->dev, "Could not find ctrl-out endpoint\n");
> +		ret = -EIO;
> +		goto fail;
> +	}
> +
> +	led->led_dev = gt683r_led_dev;
> +	ret = led_classdev_register(&led->usb_dev->dev, &led->led_dev);
> +	if (ret) {
> +		dev_err(&led->usb_dev->dev, "Could not register led_classdev\n");
> +		goto fail;
> +	}
> +
> +	mutex_init(&led->lock);
> +	INIT_WORK(&led->work, gt683r_led_work);
> +
> +	return 0;
> +fail:
> +	kfree(led->ctrl_out_buffer);
> +	led->ctrl_out_buffer = NULL;
> +
> +	kfree(led->ctrl_out_request);
> +	led->ctrl_out_request = NULL;
> +
> +	kfree(led);
> +	led = NULL;

No need to set these to NULL after free.

> +
> +	return ret;
> +}
> +
> +static void gt683r_led_disconnect(struct usb_interface *intf)
> +{
> +	struct gt683r_led *led = usb_get_intfdata(intf);
> +
> +	led_classdev_unregister(&led->led_dev);
> +	msleep(500);

Why is this sleep needed?

You need to cancel the work task synchronously here.

> +
> +	kfree(led->ctrl_out_buffer);
> +	led->ctrl_out_buffer = NULL;
> +
> +	kfree(led->ctrl_out_request);
> +	led->ctrl_out_request = NULL;
> +
> +	kfree(led);
> +	led = NULL;

No need to set these to NULL after free either.

> +}
> +
> +static struct usb_driver gt683r_led_driver = {
> +	.probe = gt683r_led_probe,
> +	.disconnect = gt683r_led_disconnect,
> +	.name = "GT683R Led Driver",
> +	.id_table = gt683r_led_id,
> +};
> +
> +module_usb_driver(gt683r_led_driver);
> +
> +MODULE_AUTHOR("Janne Kanniainen");
> +MODULE_DESCRIPTION("MSI GT683R led driver");
> +MODULE_LICENSE("GPL");

Johan
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