Re: [patch v1 1/1] leds: add driver for support Mellanox regmap LEDs for BMC

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

Hi Vadim,

On 07/26/2017 04:45 PM, Vadim Pasternak wrote:
> Hi Jacek,
> 
> Thank you very much for your comments.

You're welcome.

>> -----Original Message-----
>> From: Jacek Anaszewski [mailto:jacek.anaszewski@gmail.com]
>> Sent: Tuesday, July 25, 2017 10:56 PM
>> To: Vadim Pasternak <vadimp@mellanox.com>;
>> j.anaszewski@samsung.com; rpurdie@rpsys.net
>> Cc: linux-leds@vger.kernel.org; lee.jones@linaro.org; robh+dt@kernel.org;
>> jiri@resnulli.us
>> Subject: Re: [patch v1 1/1] leds: add driver for support Mellanox regmap LEDs
>> for BMC
>>
>> Hi Vadim,
>>
>> Thanks for the patch. Please refer to my remarks in the code below.
>>
>> On 07/25/2017 06:54 PM, Vadim Pasternak wrote:
>>> Driver obtains LED devices according to system configuration, provided
>>> through the platform data,
>>
>> Why platform data? This is confusing since you're providing DT bindings in
>> 1/2.
> 
> I think, I'll just remove "provided through the platform data".
> I put it there, because I am getting data by dev_get_platdata and 
> I'd like this driver to work not only from DT bindings, but also through the
> APIs like platform_device_register_resndata for f.e. x86 systems.

Ah, OK, I just didn't analyze the rest of series carefully enough.

>>> like mlxreg:status:green or mlxreg:status:amber and creates devices in
>>> form: "devicename:colour:function".
>>> 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>
>>> ---
>>>  MAINTAINERS                |   1 +
>>>  drivers/leds/Makefile      |   1 +
>>>  drivers/leds/leds-mlxreg.c | 345
>>> +++++++++++++++++++++++++++++++++++++++++++++
>>>  3 files changed, 347 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/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..bc1a6c3
>>> --- /dev/null
>>> +++ b/drivers/leds/leds-mlxreg.c
>>> @@ -0,0 +1,345 @@
>>> +/*
>>> + * 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/interrupt.h>
>>> +#include <linux/leds.h>
>>> +#include <linux/module.h>
>>> +#include <linux/io.h>
>>> +#include <linux/of_device.h>
>>> +#include <linux/platform_data/mlxreg.h> #include
>>> +<linux/platform_device.h> #include <linux/regmap.h> #include
>>> +<linux/wait.h> #include <linux/workqueue.h>
>>> +
>>> +#define MLXREG_LED_NAME "mlxreg"
>>
>> Why can't it be taken from DT?
>>
>>> +
>>> +/* 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 MLXREG_LED_MAX_DEFERRED	32 /* Max deferred
>> operations for LED set */
>>> +
>>> +#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 */ };
>>> +
>>> +#define MLXREG_MAP	priv->pdata->regmap
>>> +
>>> +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(MLXREG_MAP, 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(MLXREG_MAP, 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;
>>> +	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(MLXREG_MAP, led_pdata->led->reg, &regval);
>>> +	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 void
>>> +mlxreg_led_brightness_set(struct led_classdev *cled, enum
>>> +led_brightness value) {
>>> +	struct mlxreg_core_led_data *led_pdata = cdev_to_priv(cled);
>>> +
>>> +	if (in_interrupt()) {
>>
>> You wouldn't have to bother with the context you are called from if only you
>> used brightness_set_blocking op.
>>
> 
> Thanks for this pointer. Missed it.
> I'll issue v2 for both patches, since with this change I can remove these three fields from  mlxreg_core_led_data
> 	u32 bitset;
> 	u8 set_count;
> 	struct delayed_work dwork_led;
> 
>>> +		/*
>>> +		 * Handle hw access to LED in workqueue to avoid I2C locking
>> in
>>> +		 * interrupt mode. Skip if deferred operations counter is at
>>> +		 * maximum value.
>>> +		 */
>>> +		if (led_pdata->set_count == MLXREG_LED_MAX_DEFERRED -
>> 1)
>>> +			return;
>>> +
>>> +		if (!!value)
>>> +			led_pdata->bitset |= BIT(led_pdata->set_count);
>>> +		led_pdata->set_count++;
>>> +
>>> +		schedule_delayed_work(&led_pdata->dwork_led, 0);
>>
>> Similarly you could get rid of the workqueue then. It is implemented
>> internally in the LED core now.
>>
>>> +
>>> +		return;
>>> +	}
>>> +
>>> +	if (value)
>>> +		mlxreg_led_store_hw(led_pdata, led_pdata->base_color);
>>> +	else
>>> +		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 void mlxreg_led_handler(struct work_struct *work) {
>>> +	struct mlxreg_core_led_data *led_pdata = container_of(work,
>>> +			struct mlxreg_core_led_data, dwork_led.work);
>>> +
>>> +	if (led_pdata->bitset & BIT(0))
>>> +		mlxreg_led_store_hw(led_pdata, led_pdata->base_color);
>>> +	else
>>> +		mlxreg_led_store_hw(led_pdata, MLXREG_LED_IS_OFF);
>>> +
>>> +	led_pdata->bitset >>= 1;
>>> +	led_pdata->set_count--;
>>> +}
>>> +
>>> +#define MLXREG_CDEV(i)	pdata->data[i].led_cdev
>>> +
>>> +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;
>>> +	int brightness;
>>> +	int i;
>>> +	int err;
>>> +
>>> +	for (i = 0; i < pdata->counter; i++, data++) {
>>> +		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_LED_NAME, data->label);
>>
>> You should take LED name directly from the of_node. Either child DT node
>> name or label property contained by it.
>> See Documentation/devicetree/bindings/leds/common.txt.
> 
> LED name is coming from DT:
> 	status-green {
> 		reg = <0x20>;
> 		mask = <0xf0>;
> 	};
> 	status-amber {
> 		reg = <0x20>;
> 		mask = <0xf0>;
> 	};
> 	fan1-green {
> 		reg = <0x21>;
> 		mask = <0xf0>;
> 	};
> In /sys/class/leds it's shown, like:
> mlxreg:fan1:green
> mlxreg:status:amber
> mlxreg:fan1: red
> 
> I used mlxreg as a device prefix.
> Do you think it should be removed? 

No, this seems to be correct.

>>> +		MLXREG_CDEV(i).name = pdata->data[i].led_cdev_name;
>>
>> Let's avoid using these type of macros in favor of temporary variables.
>> However let's agree about final shape thereof after core mfd driver gets
>> reviewed.
>>
>>
>>> +		MLXREG_CDEV(i).brightness = brightness;
>>> +		MLXREG_CDEV(i).max_brightness = 1;
>>> +		MLXREG_CDEV(i).brightness_set =
>> mlxreg_led_brightness_set;
>>> +		MLXREG_CDEV(i).brightness_get =
>> mlxreg_led_brightness_get;
>>> +		MLXREG_CDEV(i).blink_set = mlxreg_led_blink_set;
>>> +		MLXREG_CDEV(i).flags = LED_CORE_SUSPENDRESUME;
>>> +		pdata->data[i].led = data;
>>> +		err = devm_led_classdev_register(&priv->pdev->dev,
>>> +						 &MLXREG_CDEV(i));
>>> +		if (err)
>>> +			return err;
>>> +
>>> +		if (MLXREG_CDEV(i).brightness)
>>> +			mlxreg_led_brightness_set(
>>> +				&MLXREG_CDEV(i),
>>> +				MLXREG_CDEV(i).brightness);
>>> +		dev_info(MLXREG_CDEV(i).dev,
>>> +			 "label: %s, mask: 0x%02x, offset:0x%02x\n",
>>> +			 data->label, data->mask, data->reg);
>>> +
>>> +		INIT_DELAYED_WORK(&pdata->data[i].dwork_led,
>>> +				  mlxreg_led_handler);
>>> +	}
>>> +
>>> +	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);
>>> +	struct mlxreg_core_led_platform_data *pdata = priv->pdata;
>>> +	int i;
>>> +
>>> +	for (i = 0; i < pdata->counter; i++)
>>> +		cancel_delayed_work(&pdata->data[i].dwork_led);
>>> +
>>> +	mutex_unlock(&priv->access_lock);
>>> +
>>> +	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
> 

-- 
Best regards,
Jacek Anaszewski