Re: [PATCH v5] leds: max597x: Add support for max597x

[Lee Jones <lee@kernel.org>]

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@9elements.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?


? <---------------------------------------------------------------------------

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^


> > > Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
> > > Signed-off-by: Naresh Solanki <Naresh.Solanki@9elements.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@9elements.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.

> > > +	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?

> > > +	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".

> > > +	for_each_available_child_of_node(led_node, child) {
> > > +		u32 reg;
> > > +
> > > +		if (of_property_read_u32(child, "reg", &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.

> > > +	}
> > > +
> > > +	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@9elements.com>");
> > > +MODULE_DESCRIPTION("MAX5970_hot-swap controller LED driver");
> > > +MODULE_LICENSE("GPL");
> > > 
> > > base-commit: 9d8d0d98885abba451d7ffc4885236d14ead3c9a
> > > -- 
> > > 2.39.1
> > > 
> > 
> Regards,
> Naresh

-- 
Lee Jones [李琼斯]