Re: [patch v2 1/1] leds: add driver for support Mellanox regmap LEDs for BMC

[Jacek Anaszewski <jacek.anaszewski@gmail.com>]

Hi Vadim,

Thanks for the updated patch.

I have a few more comments below.

On 07/27/2017 12:29 AM, Vadim Pasternak wrote:
> Driver obtains LED devices according to system configuration and creates
> devices in form: "devicename:color:function", like
> The full path is to be:
> /sys/class/leds/mlxreg\:status\:amber/brightness
> After timer trigger activation:
> echo timer > /sys/class/leds/mlxreg\:status\:amber/trigger
> Attributes for LED blinking will appaer in sysfs infrastructure:
> /sys/class/leds/mlxreg\:status\:amber/delay_off
> /sys/class/leds/mlxreg\:status\:amber/delay_on
> 
> LED setting is controlled through the on-board programmable devices,
> which exports its register map. This device could be attached to any
> bus type, for which register mapping is supported.
> 
> Signed-off-by: Vadim Pasternak <vadimp@mellanox.com>
> ---
> v1->v2:
>  Comments pointed out by Jacek:
>  - remove macros MLXREG_MAP and MLXREG_CDEV;
>  - brightness_set_blocking insteaf of brightness_set, this fix allows
>    removing of context validation and workqueue and also three fields from
>    struct mlxreg_core_led_data in mlxreg.h;
>  - remove MLXREG_LED_NAME;
>  - extend Kconfig description;
>  Changes added by Vadim:
>  - remove unnecessary includes after dropping workqueue;
> ---
>  MAINTAINERS                |   1 +
>  drivers/leds/Kconfig       |  10 ++
>  drivers/leds/Makefile      |   1 +
>  drivers/leds/leds-mlxreg.c | 295 +++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 307 insertions(+)
>  create mode 100644 drivers/leds/leds-mlxreg.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 205d397..ac6b0d0 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8566,6 +8566,7 @@ M:	Vadim Pasternak <vadimp@mellanox.com>
>  L:	linux-leds@vger.kernel.org
>  S:	Supported
>  F:	drivers/leds/leds-mlxcpld.c
> +F:	drivers/leds/leds-mlxreg.c
>  F:	Documentation/leds/leds-mlxcpld.txt
>  
>  MELLANOX PLATFORM DRIVER
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 594b24d..1c6563d 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -657,6 +657,16 @@ config LEDS_MLXCPLD
>  	  This option enabled support for the LEDs on the Mellanox
>  	  boards. Say Y to enabled these.
>  
> +config LEDS_MLXREG
> +	tristate "LED support for the Mellanox BMC cards"
> +	depends on LEDS_CLASS
> +	help
> +	  This option enabled support for the LEDs on the Mellanox BMC cards.
> +	  The driver can be activated from the device tree or by the direct
> +	  platform device add call. Say Y to enabled these. To compile this
> +	  driver as a module, choose 'M' here: the module will be called
> +	  leds-mlxreg.
> +
>  config LEDS_USER
>  	tristate "Userspace LED support"
>  	depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 909dae6..3eb76e5 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -69,6 +69,7 @@ obj-$(CONFIG_LEDS_IS31FL319X)		+= leds-is31fl319x.o
>  obj-$(CONFIG_LEDS_IS31FL32XX)		+= leds-is31fl32xx.o
>  obj-$(CONFIG_LEDS_PM8058)		+= leds-pm8058.o
>  obj-$(CONFIG_LEDS_MLXCPLD)		+= leds-mlxcpld.o
> +obj-$(CONFIG_LEDS_MLXREG)		+= leds-mlxreg.o
>  obj-$(CONFIG_LEDS_NIC78BX)		+= leds-nic78bx.o
>  obj-$(CONFIG_LEDS_MT6323)		+= leds-mt6323.o
>  
> diff --git a/drivers/leds/leds-mlxreg.c b/drivers/leds/leds-mlxreg.c
> new file mode 100644
> index 0000000..3e482bd
> --- /dev/null
> +++ b/drivers/leds/leds-mlxreg.c
> @@ -0,0 +1,295 @@
> +/*
> + * Copyright (c) 2017 Mellanox Technologies. All rights reserved.
> + * Copyright (c) 2017 Vadim Pasternak <vadimp@mellanox.com>
> + *
> + * Redistribution and use in source and binary forms, with or without
> + * modification, are permitted provided that the following conditions are met:
> + *
> + * 1. Redistributions of source code must retain the above copyright
> + *    notice, this list of conditions and the following disclaimer.
> + * 2. Redistributions in binary form must reproduce the above copyright
> + *    notice, this list of conditions and the following disclaimer in the
> + *    documentation and/or other materials provided with the distribution.
> + * 3. Neither the names of the copyright holders nor the names of its
> + *    contributors may be used to endorse or promote products derived from
> + *    this software without specific prior written permission.
> + *
> + * Alternatively, this software may be distributed under the terms of the
> + * GNU General Public License ("GPL") version 2 as published by the Free
> + * Software Foundation.
> + *
> + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
> + * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
> + * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
> + * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
> + * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
> + * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
> + * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
> + * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
> + * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
> + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
> + * POSSIBILITY OF SUCH DAMAGE.
> + */
> +
> +#include <linux/bitops.h>
> +#include <linux/device.h>
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/io.h>

In the alphabet i is before l :-)

> +#include <linux/of_device.h>
> +#include <linux/platform_data/mlxreg.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +/* Codes for LEDs. */
> +#define MLXREG_LED_OFFSET_HALF	0x01 /* Offset from solid: 3Hz blink */
> +#define MLXREG_LED_OFFSET_FULL	0x02 /* Offset from solid: 6Hz blink */
> +#define MLXREG_LED_IS_OFF	0x00 /* Off */
> +#define MLXREG_LED_RED_SOLID	0x05 /* Solid red */
> +#define MLXREG_LED_GREEN_SOLID	0x0D /* Solid green */
> +#define MLXREG_LED_AMBER_SOLID	0x09 /* Solid amber */
> +#define MLXREG_LED_BLINK_3HZ	167 /* ~167 msec off/on - HW support */
> +#define MLXREG_LED_BLINK_6HZ	83 /* ~83 msec off/on - HW support */
> +
> +#define cdev_to_priv(c) container_of(c, struct mlxreg_core_led_data, led_cdev)
> +
> +/**
> + * struct mlxreg_led_priv_data - platform private data:
> + *
> + * @pdev: platform device;
> + * @pdata: platform data;
> + * @access_lock: mutex for attribute IO access;
> + */
> +struct mlxreg_led_priv_data {
> +	struct platform_device *pdev;
> +	struct mlxreg_core_led_platform_data *pdata;
> +	struct mutex access_lock; /* protect IO operations */
> +};
> +
> +static int
> +mlxreg_led_store_hw(struct mlxreg_core_led_data *led_pdata, u8 vset)
> +{
> +	struct mlxreg_led_priv_data *priv = led_pdata->data_parent;
> +	u32 regval;
> +	u32 nib;
> +	int ret;
> +
> +	/*
> +	 * Each LED is controlled through low or high nibble of the relevant
> +	 * register byte. Register offset is specified by off parameter.
> +	 * Parameter vset provides color code: 0x0 for off, 0x5 for solid red,
> +	 * 0x6 for 3Hz blink red, 0xd for solid green, 0xe for 3Hz blink
> +	 * green.
> +	 * Parameter mask specifies which nibble is used for specific LED: mask
> +	 * 0xf0 - lower nibble is to be used (bits from 0 to 3), mask 0x0f -
> +	 * higher nibble (bits from 4 to 7).
> +	 */
> +	mutex_lock(&priv->access_lock);
> +
> +	ret = regmap_read(priv->pdata->regmap, led_pdata->led->reg, &regval);
> +	if (ret)
> +		goto access_error;
> +
> +	nib = (ror32(led_pdata->led->mask, led_pdata->led->bit) == 0xf0) ?
> +	      rol32(vset, led_pdata->led->bit) :
> +	      rol32(vset, led_pdata->led->bit + 4);
> +	regval = (regval & led_pdata->led->mask) | nib;
> +
> +	ret = regmap_write(priv->pdata->regmap, led_pdata->led->reg, regval);
> +
> +access_error:
> +	mutex_unlock(&priv->access_lock);
> +
> +	return ret;
> +}
> +
> +static enum led_brightness
> +mlxreg_led_get_hw(struct mlxreg_core_led_data *led_pdata)
> +{
> +	struct mlxreg_led_priv_data *priv = led_pdata->data_parent;

Please add here also:

	struct mlxreg_core_led_platform_data *pdata = priv->pdata

> +	u32 regval;
> +	int ret;
> +
> +	/*
> +	 * Each LED is controlled through low or high nibble of the relevant
> +	 * register byte. Register offset is specified by off parameter.
> +	 * Parameter vset provides color code: 0x0 for off, 0x5 for solid red,
> +	 * 0x6 for 3Hz blink red, 0xd for solid green, 0xe for 3Hz blink
> +	 * green.
> +	 * Parameter mask specifies which nibble is used for specific LED: mask
> +	 * 0xf0 - lower nibble is to be used (bits from 0 to 3), mask 0x0f -
> +	 * higher nibble (bits from 4 to 7).
> +	 */
> +	ret = regmap_read(priv->pdata->regmap, led_pdata->led->reg, &regval);

And then here in the first argument you can pass:

	pdata->regmap

It simplifies code analysis as the reader doesn't get distracted while
seeking for pdata type.

Please proceed similarly in all similar cases in this driver.

> +	if (ret < 0) {
> +		dev_warn(led_pdata->led_cdev.dev, "Failed to get current brightness, error: %d\n",
> +			 ret);
> +		/* Assume the LED is OFF */
> +		ret = LED_OFF;
> +		goto access_error;
> +	}
> +
> +	regval = regval & ~led_pdata->led->mask;
> +	regval = (ror32(led_pdata->led->mask, led_pdata->led->bit) == 0xf0) ?
> +		  ror32(regval, led_pdata->led->bit) :
> +		  ror32(regval, led_pdata->led->bit + 4);
> +	if (regval >= led_pdata->base_color &&
> +	    regval <= (led_pdata->base_color + MLXREG_LED_OFFSET_FULL))
> +		ret = LED_FULL;
> +	else
> +		ret = LED_OFF;
> +
> +access_error:
> +
> +	return ret;
> +}
> +
> +static int
> +mlxreg_led_brightness_set(struct led_classdev *cled, enum led_brightness value)
> +{
> +	struct mlxreg_core_led_data *led_pdata = cdev_to_priv(cled);
> +
> +	if (value)
> +		return mlxreg_led_store_hw(led_pdata, led_pdata->base_color);
> +	else
> +		return mlxreg_led_store_hw(led_pdata, MLXREG_LED_IS_OFF);
> +}
> +
> +static enum led_brightness
> +mlxreg_led_brightness_get(struct led_classdev *cled)
> +{
> +	struct mlxreg_core_led_data *led_pdata = cdev_to_priv(cled);
> +
> +	return mlxreg_led_get_hw(led_pdata);
> +}
> +
> +static int
> +mlxreg_led_blink_set(struct led_classdev *cled, unsigned long *delay_on,
> +		     unsigned long *delay_off)
> +{
> +	struct mlxreg_core_led_data *led_pdata = cdev_to_priv(cled);
> +	int err;
> +
> +	/*
> +	 * HW supports two types of blinking: full (6Hz) and half (3Hz).
> +	 * For delay on/off zero LED is setting to solid color. For others
> +	 * combination blinking is to be controlled by the software timer.
> +	 */
> +	if (!(*delay_on == 0 && *delay_off == 0) &&
> +	    !(*delay_on == MLXREG_LED_BLINK_3HZ &&
> +	      *delay_off == MLXREG_LED_BLINK_3HZ) &&
> +	    !(*delay_on == MLXREG_LED_BLINK_6HZ &&
> +	      *delay_off == MLXREG_LED_BLINK_6HZ))
> +		return -EINVAL;
> +
> +	if (*delay_on == MLXREG_LED_BLINK_6HZ)
> +		err = mlxreg_led_store_hw(led_pdata, led_pdata->base_color +
> +					  MLXREG_LED_OFFSET_FULL);
> +	else if (*delay_on == MLXREG_LED_BLINK_3HZ)
> +		err = mlxreg_led_store_hw(led_pdata, led_pdata->base_color +
> +					  MLXREG_LED_OFFSET_HALF);
> +	else
> +		err = mlxreg_led_store_hw(led_pdata, led_pdata->base_color);
> +
> +	return err;
> +}
> +
> +static int mlxreg_led_config(struct mlxreg_led_priv_data *priv)
> +{
> +	struct mlxreg_core_led_platform_data *pdata = priv->pdata;
> +	struct mlxreg_core_data *data = pdata->data->led;

Ditto.

> +	struct led_classdev *led_cdev;
> +	int brightness;
> +	int i;
> +	int err;
> +
> +	for (i = 0; i < pdata->counter; i++, data++) {
> +		led_cdev = &pdata->data[i].led_cdev;
> +		pdata->data[i].data_parent = priv;
> +		if (strstr(data->label, "red")) {
> +			brightness = LED_OFF;
> +			pdata->data[i].base_color = MLXREG_LED_RED_SOLID;
> +		} else if (strstr(data->label, "amber")) {
> +			brightness = LED_OFF;
> +			pdata->data[i].base_color = MLXREG_LED_AMBER_SOLID;
> +		} else {
> +			brightness = LED_OFF;
> +			pdata->data[i].base_color = MLXREG_LED_GREEN_SOLID;
> +		}
> +		sprintf(pdata->data[i].led_cdev_name, "%s:%s", "mlxreg",
> +			data->label);
> +		led_cdev->name = pdata->data[i].led_cdev_name;
> +		led_cdev->brightness = brightness;
> +		led_cdev->max_brightness = 1;

We have now LED_ON = 1 enum.

> +		led_cdev->brightness_set_blocking =
> +						mlxreg_led_brightness_set;
> +		led_cdev->brightness_get = mlxreg_led_brightness_get;
> +		led_cdev->blink_set = mlxreg_led_blink_set;
> +		led_cdev->flags = LED_CORE_SUSPENDRESUME;
> +		pdata->data[i].led = data;
> +		err = devm_led_classdev_register(&priv->pdev->dev, led_cdev);
> +		if (err)
> +			return err;
> +
> +		if (led_cdev->brightness)
> +			mlxreg_led_brightness_set(led_cdev,
> +						  led_cdev->brightness);
> +		dev_info(led_cdev->dev, "label: %s, mask: 0x%02x, offset:0x%02x\n",
> +			 data->label, data->mask, data->reg);
> +	}
> +
> +	return 0;
> +}
> +
> +static int mlxreg_led_probe(struct platform_device *pdev)
> +{
> +	struct mlxreg_core_led_platform_data *pdata;
> +	struct mlxreg_led_priv_data *priv;
> +
> +	pdata = dev_get_platdata(&pdev->dev);
> +	if (!pdata) {
> +		dev_err(&pdev->dev, "Failed to get platform data.\n");
> +		return -EINVAL;
> +	}
> +
> +	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
> +	if (!priv)
> +		return -ENOMEM;
> +
> +	mutex_init(&priv->access_lock);
> +	priv->pdev = pdev;
> +	priv->pdata = pdata;
> +
> +	return mlxreg_led_config(priv);
> +}
> +
> +static int mlxreg_led_remove(struct platform_device *pdev)
> +{
> +	struct mlxreg_led_priv_data *priv = dev_get_drvdata(&pdev->dev);
> +
> +	mutex_unlock(&priv->access_lock);

mutex_destroy() would be more relevant here.

> +
> +	return 0;
> +}
> +
> +static const struct of_device_id mlxreg_led_dt_match[] = {
> +	{ .compatible = "mellanox,leds-mlxreg" },
> +	{ },
> +};
> +MODULE_DEVICE_TABLE(of, mlxreg_dt_match);
> +
> +static struct platform_driver mlxreg_led_driver = {
> +	.driver = {
> +	    .name = "leds-mlxreg",
> +	    .of_match_table = of_match_ptr(mlxreg_led_dt_match),
> +	},
> +	.probe = mlxreg_led_probe,
> +	.remove = mlxreg_led_remove,
> +};
> +
> +module_platform_driver(mlxreg_led_driver);
> +
> +MODULE_AUTHOR("Vadim Pasternak <vadimp@mellanox.com>");
> +MODULE_DESCRIPTION("Mellanox LED regmap driver");
> +MODULE_LICENSE("Dual BSD/GPL");
> +MODULE_ALIAS("platform:leds-mlxreg");
> 

-- 
Best regards,
Jacek Anaszewski