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Message-ID: <40b72025-16a8-1af5-d69f-659d37cdeab9@9elements.com>
Date: Thu, 20 Apr 2023 22:50:39 +0530
From: Naresh Solanki <naresh.solanki@...ements.com>
To: Lee Jones <lee@...nel.org>
Cc: Pavel Machek <pavel@....cz>,
Patrick Rudolph <patrick.rudolph@...ements.com>,
linux-kernel@...r.kernel.org, linux-leds@...r.kernel.org
Subject: Re: [PATCH v5] leds: max597x: Add support for max597x
Hi Lee,
On 20-04-2023 07:24 pm, Lee Jones wrote:
> On Thu, 20 Apr 2023, Naresh Solanki wrote:
>
>> Hi Lee,
>>
>> On 20-04-2023 05:20 pm, Lee Jones wrote:
>>> On Mon, 17 Apr 2023, Naresh Solanki wrote:
>>>
>>>> From: Patrick Rudolph <patrick.rudolph@...ements.com>
>>>>
>>>> max597x is hot swap controller with indicator LED support.
>>>> This driver uses DT property to configure led during boot time &
>>>> also provide the LED control in sysfs.
>>>>
>>>> DTS example:
>>>> i2c {
>>>> #address-cells = <1>;
>>>> #size-cells = <0>;
>>>> regulator@3a {
>>>> compatible = "maxim,max5978";
>>>> reg = <0x3a>;
>>>> vss1-supply = <&p3v3>;
>>>>
>>>> regulators {
>>>> sw0_ref_0: sw0 {
>>>> shunt-resistor-micro-ohms = <12000>;
>>>> };
>>>> };
>>>>
>>>> leds {
>>>> #address-cells = <1>;
>>>> #size-cells = <0>;
>>>> led@0 {
>>>> reg = <0>;
>>>> label = "ssd0:green";
>>>> default-state = "on";
>>>> };
>>>> led@1 {
>>>> reg = <1>;
>>>> label = "ssd1:green";
>>>> default-state = "on";
>>>> };
>>>> };
>>>> };
>>>> };
>>>
>>> Where is the DT binding document for this?
https://git.kernel.org/pub/scm/linux/kernel/git/lee/mfd.git/tree/Documentation/devicetree/bindings/mfd/maxim,max5970.yaml?h=for-mfd-next
>
>
> ? <---------------------------------------------------------------------------
>
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
>
>>>> Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
>>>> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
>>>> ...
>>>> Changes in V5:
>>>> - Update commit message
>>>> - Fix comments
>>>> - Add necessary new line
>>>> Changes in V4:
>>>> - Remove unwanted preinitialise
>>>> - Remove unneeded line breaks
>>>> - Fix variable name to avoid confusion
>>>> - Update module description to mention LED driver.
>>>> Changes in V3:
>>>> - Remove of_node_put as its handled by for loop
>>>> - Print error if an LED fails to register.
>>>> - Update driver name in Kconfig description
>>>> - Remove unneeded variable assignment
>>>> - Use devm_led_classdev_register to reget led
>>>> Changes in V2:
>>>> - Fix regmap update
>>>> - Remove devm_kfree
>>>> - Remove default-state
>>>> - Add example dts in commit message
>>>> - Fix whitespace in Kconfig
>>>> - Fix comment
>>>> ---
>>>> drivers/leds/Kconfig | 11 ++++
>>>> drivers/leds/Makefile | 1 +
>>>> drivers/leds/leds-max597x.c | 115 ++++++++++++++++++++++++++++++++++++
>>>> 3 files changed, 127 insertions(+)
>>>> create mode 100644 drivers/leds/leds-max597x.c
>>>>
>>>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>>>> index 9dbce09eabac..60004cb8c257 100644
>>>> --- a/drivers/leds/Kconfig
>>>> +++ b/drivers/leds/Kconfig
>>>> @@ -590,6 +590,17 @@ config LEDS_ADP5520
>>>> To compile this driver as a module, choose M here: the module will
>>>> be called leds-adp5520.
>>>> +config LEDS_MAX597X
>>>> + tristate "LED Support for Maxim 597x"
>>>> + depends on LEDS_CLASS
>>>> + depends on MFD_MAX597X
>>>> + help
>>>> + This option enables support for the Maxim MAX5970 & MAX5978 smart
>>>> + switch indication LEDs via the I2C bus.
>>>> +
>>>> + To compile this driver as a module, choose M here: the module will
>>>> + be called leds-max597x.
>>>> +
>>>> config LEDS_MC13783
>>>> tristate "LED Support for MC13XXX PMIC"
>>>> depends on LEDS_CLASS
>>>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
>>>> index d30395d11fd8..da1192e40268 100644
>>>> --- a/drivers/leds/Makefile
>>>> +++ b/drivers/leds/Makefile
>>>> @@ -53,6 +53,7 @@ obj-$(CONFIG_LEDS_LP8501) += leds-lp8501.o
>>>> obj-$(CONFIG_LEDS_LP8788) += leds-lp8788.o
>>>> obj-$(CONFIG_LEDS_LP8860) += leds-lp8860.o
>>>> obj-$(CONFIG_LEDS_LT3593) += leds-lt3593.o
>>>> +obj-$(CONFIG_LEDS_MAX597X) += leds-max597x.o
>>>> obj-$(CONFIG_LEDS_MAX77650) += leds-max77650.o
>>>> obj-$(CONFIG_LEDS_MAX8997) += leds-max8997.o
>>>> obj-$(CONFIG_LEDS_MC13783) += leds-mc13783.o
>>>> diff --git a/drivers/leds/leds-max597x.c b/drivers/leds/leds-max597x.c
>>>> new file mode 100644
>>>> index 000000000000..edbd43018822
>>>> --- /dev/null
>>>> +++ b/drivers/leds/leds-max597x.c
>>>> @@ -0,0 +1,115 @@
>>>> +// SPDX-License-Identifier: GPL-2.0
>>>> +/*
>>>> + * Device driver for leds in MAX5970 and MAX5978 IC
>>>
>>> "MAX5970 and MAX5978 IC LED support"
>>>
>>>> + * Copyright (c) 2022 9elements GmbH
>>>> + *
>>>> + * Author: Patrick Rudolph <patrick.rudolph@...ements.com>
>>>> + */
>>>> +
>>>> +#include <linux/leds.h>
>>>> +#include <linux/mfd/max597x.h>
>>>> +#include <linux/of.h>
>>>> +#include <linux/platform_device.h>
>>>> +#include <linux/regmap.h>
>>>> +
>>>> +#define ldev_to_maxled(c) container_of(c, struct max597x_led, cdev)
>>>> +
>>>> +struct max597x_led {
>>>> + struct regmap *regmap;
>>>> + struct led_classdev cdev;
>>>> + unsigned int index;
>>>> +};
>>>> +
>>>> +static int max597x_led_set_brightness(struct led_classdev *cdev,
>>>> + enum led_brightness brightness)
>>>> +{
>>>> + struct max597x_led *ddata = ldev_to_maxled(cdev);
>>>> + int ret, val;
>>>> +
>>>> + if (!ddata->regmap)
>>>> + return -ENODEV;
>>>> +
>>>> + /* Set/clear corresponding bit for given led index */
>>>> + val = !brightness ? BIT(ddata->index) : 0;
>>>> +
>>>> + ret = regmap_update_bits(ddata->regmap, MAX5970_REG_LED_FLASH, BIT(ddata->index), val);
>>>> + if (ret < 0)
>>>> + dev_err(cdev->dev, "failed to set brightness %d", ret);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int max597x_setup_led(struct device *dev, struct regmap *regmap, struct device_node *nc,
>>>> + u32 reg)
>>>> +{
>>>> + struct max597x_led *ddata;
>>>> + int ret;
>>>> +
>>>> + ddata = devm_kzalloc(dev, sizeof(struct max597x_led), GFP_KERNEL);
>>>> + if (!ddata)
>>>> + return -ENOMEM;
>>>> +
>>>> + if (of_property_read_string(nc, "label", &ddata->cdev.name))
>>>> + ddata->cdev.name = nc->name;
>>>> +
>>>> + ddata->cdev.max_brightness = 1;
>>>> + ddata->cdev.brightness_set_blocking = max597x_led_set_brightness;
>>>> + ddata->cdev.default_trigger = "none";
>>>> + ddata->index = reg;
>>>> + ddata->regmap = regmap;
>>>> +
>>>> + ret = devm_led_classdev_register(dev, &ddata->cdev);
>>>> + if (ret)
>>>> + dev_err(dev, "Error initializing LED %s", ddata->cdev.name);
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static int max597x_led_probe(struct platform_device *pdev)
>>>> +{
>>>> + struct device_node *np = dev_of_node(pdev->dev.parent);
>>>
>>> My previous question about having its own compatible string was ignored.
>> As previously stated, the MFD driver for max597x already has a compatible
>> string that serves its purpose, so I opted not to include a separate
>> compatible string for the leaf driver.
>> Prior to implementing this approach, I reviewed other implementations within
>> the MFD driver, such as the sy7636 which uses the similar approach in leaf
>> driver.
>
> I'm not saying it's never been done. However, most of the time
> leaf/child devices have their own compatible string and node.
True.
>
>>>> + struct regmap *regmap;
>>>> + struct device_node *led_node;
>>>> + struct device_node *child;
>>>> + int ret = 0;
>>>> +
>>>> + regmap = dev_get_regmap(pdev->dev.parent, NULL);
>>>> + if (!regmap)
>>>> + return -EPROBE_DEFER;
>
> Will other child devices have be using the parent's regmap too?
Yes
>
>>>> + led_node = of_get_child_by_name(np, "leds");
>>>> + if (!led_node)
>>>> + return -ENODEV;
>
> It's odd for a device to be referring to itself as the "child".
As this is leaf driver, LED specific info is present in "leds" node in DT.
>
>>>> + for_each_available_child_of_node(led_node, child) {
>>>> + u32 reg;
>>>> +
>>>> + if (of_property_read_u32(child, "reg", ®))
>>>> + continue;
>>>> +
>>>> + if (reg >= MAX597X_NUM_LEDS) {
>>>> + dev_err(&pdev->dev, "invalid LED (%u >= %d)\n", reg,
>>>> + MAX597X_NUM_LEDS);
>>>> + continue;
>>>> + }
>>>> +
>>>> + ret = max597x_setup_led(&pdev->dev, regmap, child, reg);
>>>> + if (ret < 0)
>>>> + dev_err(&pdev->dev, "Failed to initialize LED %u\n", reg);
>>>
>>> You've ignored my previous review.
>> I would like to clarify that I did not intend to overlook your previous
>> review comment. Rather, I have taken it into consideration and evaluated it
>> in the context of the current approach, which is derived from the code in
>> other LED drivers.
>> To eliminate any potential confusion, it may be best to adopt a consistent
>> approach that all LED drivers should adhere to in similar circumstances.
>
> I agree. That's start with this one.
>
> You should not error and continue. If you encounter an error, please
> unwind what you have done before and return the error.
Ack.
>
>>>> + }
>>>> +
>>>> + return ret;
>>>> +}
>>>> +
>>>> +static struct platform_driver max597x_led_driver = {
>>>> + .driver = {
>>>> + .name = "max597x-led",
>>>> + },
>>>> + .probe = max597x_led_probe,
>>>> +};
>>>> +
>>>> +module_platform_driver(max597x_led_driver);
>>>> +MODULE_AUTHOR("Patrick Rudolph <patrick.rudolph@...ements.com>");
>>>> +MODULE_DESCRIPTION("MAX5970_hot-swap controller LED driver");
>>>> +MODULE_LICENSE("GPL");
>>>>
>>>> base-commit: 9d8d0d98885abba451d7ffc4885236d14ead3c9a
>>>> --
>>>> 2.39.1
>>>>
>>>
>> Regards,
>> Naresh
>
Regards,
Naresh
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