[RFC,2/3] leds: upboard: Add LED support

Allow userspace to use the on-board LEDs as "upboard:<color>:".

Signed-off-by: Javier Arteaga <javier@emutex.com>
---
 drivers/leds/Kconfig        | 10 +++++
 drivers/leds/Makefile       |  1 +
 drivers/leds/leds-upboard.c | 87 +++++++++++++++++++++++++++++++++++++
 drivers/mfd/upboard.c       | 19 ++++++++
 include/linux/mfd/upboard.h |  5 +++
 5 files changed, 122 insertions(+)
 create mode 100644 drivers/leds/leds-upboard.c

Hi Javier,

Thank you for the patch. Just two trivial issues below.

On 04/21/2018 10:30 AM, Javier Arteaga wrote:
> Allow userspace to use the on-board LEDs as "upboard:<color>:".
> 
> Signed-off-by: Javier Arteaga <javier@emutex.com>
> ---
>  drivers/leds/Kconfig        | 10 +++++
>  drivers/leds/Makefile       |  1 +
>  drivers/leds/leds-upboard.c | 87 +++++++++++++++++++++++++++++++++++++
>  drivers/mfd/upboard.c       | 19 ++++++++
>  include/linux/mfd/upboard.h |  5 +++
>  5 files changed, 122 insertions(+)
>  create mode 100644 drivers/leds/leds-upboard.c
> 
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 2c896c0e69e1..2e77b46f2802 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -722,6 +722,16 @@ config LEDS_NIC78BX
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called leds-nic78bx.
>  
> +config LEDS_UPBOARD
> +	tristate "LED support for the UP Squared"
> +	depends on LEDS_CLASS
> +	depends on MFD_UPBOARD
> +	help
> +	  This option enables support for the LEDs on the UP Squared board.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called leds-upboard.
> +
>  comment "LED Triggers"
>  source "drivers/leds/trigger/Kconfig"
>  
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 91eca81cae82..4008e2061e1f 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -76,6 +76,7 @@ obj-$(CONFIG_LEDS_MLXREG)		+= leds-mlxreg.o
>  obj-$(CONFIG_LEDS_NIC78BX)		+= leds-nic78bx.o
>  obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
>  obj-$(CONFIG_LEDS_LM3692X)		+= leds-lm3692x.o
> +obj-$(CONFIG_LEDS_UPBOARD)		+= leds-upboard.o
>  
>  # LED SPI Drivers
>  obj-$(CONFIG_LEDS_DAC124S085)		+= leds-dac124s085.o
> diff --git a/drivers/leds/leds-upboard.c b/drivers/leds/leds-upboard.c
> new file mode 100644
> index 000000000000..e9d7a1fbcde4
> --- /dev/null
> +++ b/drivers/leds/leds-upboard.c
> @@ -0,0 +1,87 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * UP Board LED driver
> + *
> + * Copyright (c) 2018, Emutex Ltd.
> + *
> + * Author: Javier Arteaga <javier@emutex.com>
> + */

Please use uniform '//' comment style here.

> +
> +#include <linux/kernel.h>
> +#include <linux/leds.h>
> +#include <linux/mfd/upboard.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +struct upboard_led {
> +	struct regmap_field *field;
> +	struct led_classdev cdev;
> +};
> +
> +static enum led_brightness upboard_led_brightness_get(struct led_classdev *cdev)
> +{
> +	struct upboard_led *led = container_of(cdev, struct upboard_led, cdev);
> +	int brightness = 0;
> +
> +	regmap_field_read(led->field, &brightness);
> +
> +	return brightness;
> +};
> +
> +static void upboard_led_brightness_set(struct led_classdev *cdev,
> +				       enum led_brightness brightness)
> +{
> +	struct upboard_led *led = container_of(cdev, struct upboard_led, cdev);
> +
> +	regmap_field_write(led->field, brightness != LED_OFF);
> +};
> +
> +static int __init upboard_led_probe(struct platform_device *pdev)
> +{
> +	struct upboard_led_data * const pdata = pdev->dev.platform_data;
> +	struct upboard *upboard;
> +	struct upboard_led *led;
> +	struct reg_field conf = {
> +		.reg = UPBOARD_REG_FUNC_EN0,
> +	};
> +
> +	if (!pdev->dev.parent)
> +		return -EINVAL;
> +
> +	upboard = dev_get_drvdata(pdev->dev.parent);
> +	if (!upboard || !pdata)
> +		return -EINVAL;
> +
> +	led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
> +	if (!led)
> +		return -ENOMEM;
> +
> +	conf.lsb = pdata->id;
> +	conf.msb = pdata->id;
> +	led->field = devm_regmap_field_alloc(&pdev->dev, upboard->regmap, conf);
> +	if (IS_ERR(led->field))
> +		return PTR_ERR(led->field);
> +
> +	led->cdev.brightness_get = upboard_led_brightness_get;
> +	led->cdev.brightness_set = upboard_led_brightness_set;
> +	led->cdev.name = devm_kasprintf(&pdev->dev, GFP_KERNEL, "upboard:%s:",
> +					pdata->color);
> +	if (!led->cdev.name)
> +		return -ENOMEM;
> +
> +	return devm_led_classdev_register(&pdev->dev, &led->cdev);
> +};
> +
> +static struct platform_driver upboard_led_driver = {
> +	.driver = {
> +		.name = "upboard-led",
> +	},
> +};
> +
> +module_platform_driver_probe(upboard_led_driver, upboard_led_probe);
> +
> +MODULE_ALIAS("platform:upboard-led");
> +MODULE_AUTHOR("Javier Arteaga <javier@emutex.com>");
> +MODULE_DESCRIPTION("UP Board LED driver");
> +MODULE_LICENSE("GPL");

s/GPL/GPL v2/


> diff --git a/drivers/mfd/upboard.c b/drivers/mfd/upboard.c
> index 8bae450cb83d..6e4767e4dc41 100644
> --- a/drivers/mfd/upboard.c
> +++ b/drivers/mfd/upboard.c
> @@ -79,6 +79,14 @@ struct upboard_data {
>  	size_t ncells;
>  };
>  
> +#define UPBOARD_LED_CELL(led_data, n)                   \
> +	{                                               \
> +		.name = "upboard-led",                  \
> +		.id = (n),                              \
> +		.platform_data = &led_data[(n)],        \
> +		.pdata_size = sizeof(*(led_data)),      \
> +	}
> +
>  /* UP Squared */
>  
>  static const struct regmap_range upboard_up2_readable_ranges[] = {
> @@ -116,7 +124,18 @@ static const struct regmap_config upboard_up2_regmap_config = {
>  	.wr_table = &upboard_up2_writable_table,
>  };
>  
> +static struct upboard_led_data upboard_up2_led_data[] = {
> +	{ .id = 0, .color = "blue" },
> +	{ .id = 1, .color = "yellow" },
> +	{ .id = 2, .color = "green" },
> +	{ .id = 3, .color = "red" },
> +};
> +
>  static const struct mfd_cell upboard_up2_mfd_cells[] = {
> +	UPBOARD_LED_CELL(upboard_up2_led_data, 0),
> +	UPBOARD_LED_CELL(upboard_up2_led_data, 1),
> +	UPBOARD_LED_CELL(upboard_up2_led_data, 2),
> +	UPBOARD_LED_CELL(upboard_up2_led_data, 3),
>  };
>  
>  static const struct upboard_data upboard_up2_data = {
> diff --git a/include/linux/mfd/upboard.h b/include/linux/mfd/upboard.h
> index d9dd214f4d29..eed68caa23ce 100644
> --- a/include/linux/mfd/upboard.h
> +++ b/include/linux/mfd/upboard.h
> @@ -62,4 +62,9 @@ struct upboard {
>  	struct gpio_desc *dataout_gpio;
>  };
>  
> +struct upboard_led_data {
> +	unsigned int id;
> +	const char *color;
> +};
> +
>  #endif /*  __LINUX_MFD_UPBOARD_H */
>

Hi Jacek,

On Wed, Apr 25, 2018 at 08:25:59PM +0200, Jacek Anaszewski wrote:
> > diff --git a/drivers/leds/leds-upboard.c b/drivers/leds/leds-upboard.c
> > new file mode 100644
> > index 000000000000..e9d7a1fbcde4
> > --- /dev/null
> > +++ b/drivers/leds/leds-upboard.c
> > @@ -0,0 +1,87 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * UP Board LED driver
> > + *
> > + * Copyright (c) 2018, Emutex Ltd.
> > + *
> > + * Author: Javier Arteaga <javier@emutex.com>
> > + */
> 
> Please use uniform '//' comment style here.

Will do!

(I was actually wondering about this one as I've seen both mixed C/C++
and C++-only comment blocks in other drivers, but I see now your
suggestion is indeed preferred style.)

> > +MODULE_LICENSE("GPL");
> 
> s/GPL/GPL v2/

I've fixed this now too.

Aside: this thread was one I mistakenly posted without proper Cc's to
linux-kernel. Other review comments are at:

    "[RFC PATCH RESEND 0/3] UP Squared board drivers"
    https://lkml.kernel.org/r/20180421085009.28773-1-javier@emutex.com

Thank you for the review!
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