Date:   Mon, 6 Mar 2017 22:41:03 +0100
From:   Jacek Anaszewski <jacek.anaszewski@...il.com>
To:     Sebastian Reichel <sre@...nel.org>,
        Tony Lindgren <tony@...mide.com>,
        Richard Purdie <rpurdie@...ys.net>, Pavel Machek <pavel@....cz>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        linux-leds@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] leds: cpcap: new driver

Hi Sebastian,

Thanks for the patch. I have few comments in the code below.

On 03/05/2017 06:22 PM, Sebastian Reichel wrote:
> Motorola CPCAP is a PMIC found in multiple smartphones.
> This driver adds support for the chip's LED controllers.
> It has explicit support for all controllers used by the
> Droid 4. Since no datasheets are available the other
> available controllers are not supported until somebody
> verified, that the register layout matches.
> 
> Signed-off-by: Sebastian Reichel <sre@...nel.org>
> ---
>  .../devicetree/bindings/leds/cpcap-leds.txt        |  29 +++
>  drivers/leds/Kconfig                               |   9 +
>  drivers/leds/Makefile                              |   1 +
>  drivers/leds/leds-cpcap.c                          | 248 +++++++++++++++++++++
>  4 files changed, 287 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/leds/cpcap-leds.txt
>  create mode 100644 drivers/leds/leds-cpcap.c
> 
> diff --git a/Documentation/devicetree/bindings/leds/cpcap-leds.txt b/Documentation/devicetree/bindings/leds/cpcap-leds.txt
> new file mode 100644
> index 000000000000..d523f8c3c358
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/leds/cpcap-leds.txt
> @@ -0,0 +1,29 @@
> +Motorola CPCAP PMIC LEDs
> +------------------------
> +
> +This module is part of the CPCAP. For more details about the whole
> +chip see Documentation/devicetree/bindings/mfd/motorola-cpcap.txt.
> +
> +Requires node properties:
> +- compatible: should be one of
> +   * "motorola,cpcap-led-mdl"		(Main Display Lighting)
> +   * "motorola,cpcap-led-kl"		(Keyboard Lighting)
> +   * "motorola,cpcap-led-adl"		(Aux Display Lighting)
> +   * "motorola,cpcap-led-red"		(Red Triode)
> +   * "motorola,cpcap-led-green"		(Green Triode)
> +   * "motorola,cpcap-led-blue"		(Blue Triode)
> +   * "motorola,cpcap-led-cf"		(Camera Flash)
> +   * "motorola,cpcap-led-bt"		(Bluetooth)
> +   * "motorola,cpcap-led-cp"		(Camera Privacy LED)
> +- label: The label for this LED

Please change the property description to the following:

see Documentation/devicetree/bindings/leds/common.txt

> +- vdd-supply: A phandle to the regulator powering the LED
> +
> +Example:
> +
> +&cpcap {
> +	cpcap_led_red: red-led {
> +		compatible = "motorola,cpcap-led-red";
> +		label = "cpcap:red";
> +		vdd-supply = <&sw5>;
> +	};
> +};
> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
> index 275f467956ee..043f02a4fe73 100644
> --- a/drivers/leds/Kconfig
> +++ b/drivers/leds/Kconfig
> @@ -76,6 +76,15 @@ config LEDS_BCM6358
>  	  This option enables support for LEDs connected to the BCM6358
>  	  LED HW controller accessed via MMIO registers.
>  
> +config LEDS_CPCAP
> +	tristate "LED Support for Motorola CPCAP"
> +	depends on LEDS_CLASS
> +	depends on MFD_CPCAP
> +	depends on OF
> +	help
> +	  This option enables support for LEDs offered by Motorola's
> +	  CPCAP PMIC.
> +
>  config LEDS_LM3530
>  	tristate "LCD Backlight driver for LM3530"
>  	depends on LEDS_CLASS
> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
> index 6b8273736478..333e84ce5d3b 100644
> --- a/drivers/leds/Makefile
> +++ b/drivers/leds/Makefile
> @@ -11,6 +11,7 @@ obj-$(CONFIG_LEDS_AAT1290)		+= leds-aat1290.o
>  obj-$(CONFIG_LEDS_BCM6328)		+= leds-bcm6328.o
>  obj-$(CONFIG_LEDS_BCM6358)		+= leds-bcm6358.o
>  obj-$(CONFIG_LEDS_BD2802)		+= leds-bd2802.o
> +obj-$(CONFIG_LEDS_CPCAP)		+= leds-cpcap.o
>  obj-$(CONFIG_LEDS_LOCOMO)		+= leds-locomo.o
>  obj-$(CONFIG_LEDS_LM3530)		+= leds-lm3530.o
>  obj-$(CONFIG_LEDS_LM3533)		+= leds-lm3533.o
> diff --git a/drivers/leds/leds-cpcap.c b/drivers/leds/leds-cpcap.c
> new file mode 100644
> index 000000000000..e2fe13aae2f1
> --- /dev/null
> +++ b/drivers/leds/leds-cpcap.c
> @@ -0,0 +1,248 @@
> +/*
> + * Copyright (c) 2017 Sebastian Reichel <sre@...nel.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + */
> +
> +#define DEBUG

This is stray debug macro I believe.

> +
> +#include <linux/leds.h>
> +#include <linux/module.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/mfd/motorola-cpcap.h>

Please sort these directives alphabetically. I.e. the last entry
should go after linux/leds.h.

> +
> +#define CPCAP_LED_NO_CURRENT 0x0001
> +#define CPCAP_LED_OFF 0x0000
> +
> +struct cpcap_led_info {
> +	u16 reg;
> +	u16 mask;
> +	u16 limit;
> +	u16 init_mask;
> +	u16 init_val;
> +};
> +
> +static const struct cpcap_led_info cpcap_led_red = {
> +	.reg	= CPCAP_REG_REDC,
> +	.mask	= 0x03FF,
> +	.limit	= 31,
> +};
> +
> +static const struct cpcap_led_info cpcap_led_green = {
> +	.reg	= CPCAP_REG_GREENC,
> +	.mask	= 0x03FF,
> +	.limit	= 31,
> +};
> +
> +static const struct cpcap_led_info cpcap_led_blue = {
> +	.reg	= CPCAP_REG_BLUEC,
> +	.mask	= 0x03FF,
> +	.limit	= 31,
> +};
> +
> +/* aux display light */
> +static const struct cpcap_led_info cpcap_led_adl = {
> +	.reg		= CPCAP_REG_ADLC,
> +	.mask		= 0x000F,
> +	.limit		= 1,
> +	.init_mask	= 0x7FFF,
> +	.init_val	= 0x5FF0,
> +};
> +
> +/* camera privacy led */
> +static const struct cpcap_led_info cpcap_led_cp = {
> +	.reg		= CPCAP_REG_CLEDC,
> +	.mask		= 0x0007,
> +	.limit		= 1,
> +	.init_mask	= 0x03FF,
> +	.init_val	= 0x0008,
> +};
> +
> +/* unsupported led */
> +static const struct cpcap_led_info cpcap_led_unsup = {
> +	.reg		= 0x0000,
> +};
> +
> +struct cpcap_led {
> +	struct led_classdev led;
> +	const struct cpcap_led_info *info;
> +	struct device *dev;
> +	struct regmap *regmap;
> +	struct regulator *vdd;
> +	bool powered;
> +
> +	u32 current_limit;
> +};
> +
> +static u16 cpcap_led_val(u8 current_limit, u8 duty_cycle)
> +{
> +	current_limit &= 0x1f; /* 5 bit */
> +	duty_cycle &= 0x0f; /* 4 bit */
> +
> +	return current_limit << 4 | duty_cycle;
> +}
> +
> +static int cpcap_led_set_power(struct cpcap_led *led, bool status)
> +{
> +	int err;
> +
> +	if (status == led->powered)
> +		return 0;
> +
> +	if (status)
> +		err = regulator_enable(led->vdd);
> +	else
> +		err = regulator_disable(led->vdd);
> +
> +	if (err) {
> +		dev_err(led->dev, "regulator failure: %d", err);
> +		return err;
> +	}
> +
> +	led->powered = status;
> +
> +	return 0;
> +}
> +
> +static int cpcap_led_set(struct led_classdev *ledc, enum led_brightness value)
> +{
> +	struct cpcap_led *led = container_of(ledc, struct cpcap_led, led);
> +	int brightness;
> +	int err;

You need mutex protection here so as not to leave the device in an
inconsistent state when concurrent access occurs.
The operation of brightness setting is not atomic here.

> +	if (value > LED_OFF) {
> +		err = cpcap_led_set_power(led, true);
> +		if (err)
> +			return err;
> +	}
> +
> +	if (value == LED_OFF) {
> +		/* Avoid HW issue by turning off current before duty cycle */
> +		err = regmap_update_bits(led->regmap,
> +			led->info->reg, led->info->mask, CPCAP_LED_NO_CURRENT);
> +		if (err) {
> +			dev_err(led->dev, "regmap failed: %d", err);
> +			return err;
> +		}
> +
> +		brightness = CPCAP_LED_OFF;
> +	} else {
> +		brightness = cpcap_led_val(value, 0x01);

Please add a macro for 0x01.

> +	}
> +
> +	dev_dbg(led->dev, "regmap: reg=%04x mask=%04x val=%04x",
> +		led->info->reg, led->info->mask, brightness);

Please remove this debug logging. You can always enable CONFIG_DEBUG_FS.

> +	err = regmap_update_bits(led->regmap, led->info->reg, led->info->mask,
> +		brightness);
> +	if (err) {
> +		dev_err(led->dev, "regmap failed: %d", err);
> +		return err;
> +	}
> +
> +	if (value == LED_OFF) {

Why can't we accomplish this in the second condition?

> +		err = cpcap_led_set_power(led, false);
> +		if (err)
> +			return err;
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id cpcap_led_of_match[] = {
> +	{ .compatible = "motorola,cpcap-led-red", .data = &cpcap_led_red },
> +	{ .compatible = "motorola,cpcap-led-green", .data = &cpcap_led_green },
> +	{ .compatible = "motorola,cpcap-led-blue",  .data = &cpcap_led_blue },
> +	{ .compatible = "motorola,cpcap-led-adl", .data = &cpcap_led_adl },
> +	{ .compatible = "motorola,cpcap-led-cp", .data = &cpcap_led_cp },
> +
> +	{ .compatible = "motorola,cpcap-led-cf", .data = &cpcap_led_unsup },
> +	{ .compatible = "motorola,cpcap-led-mdl", .data = &cpcap_led_unsup },
> +	{ .compatible = "motorola,cpcap-led-kl", .data = &cpcap_led_unsup },
> +	{ .compatible = "motorola,cpcap-led-bt", .data = &cpcap_led_unsup },

Does it make sense to provide entries for unsupported LEDs?

> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, cpcap_led_of_match);
> +
> +static int cpcap_led_probe(struct platform_device *pdev)
> +{
> +	const struct of_device_id *match;
> +	struct cpcap_led *led;
> +	int err;
> +
> +	match = of_match_device(of_match_ptr(cpcap_led_of_match), &pdev->dev);
> +	if (!match || !match->data)
> +		return -EINVAL;
> +
> +	led = devm_kzalloc(&pdev->dev, sizeof(*led), GFP_KERNEL);
> +	if (!led)
> +		return -ENOMEM;
> +	platform_set_drvdata(pdev, led);
> +	led->info = match->data;
> +	led->dev = &pdev->dev;
> +
> +	if (led->info->reg == 0x0000) {
> +		dev_err(led->dev, "Unsupported LED");
> +		return -ENODEV;
> +	}
> +
> +	led->regmap = dev_get_regmap(pdev->dev.parent, NULL);
> +	if (!led->regmap)
> +		return -ENODEV;
> +
> +	led->vdd = devm_regulator_get(&pdev->dev, "vdd");
> +	if (IS_ERR(led->vdd)) {
> +		err = PTR_ERR(led->vdd);
> +		dev_err(led->dev, "Couldn't get regulator: %d", err);
> +		return err;
> +	}
> +
> +	err = device_property_read_string(&pdev->dev, "label", &led->led.name);
> +	if (err) {
> +		dev_err(led->dev, "Couldn't read led label: %d", err);
> +		return err;
> +	}
> +
> +	led->led.max_brightness = led->info->limit;
> +
> +	led->led.brightness_set_blocking = cpcap_led_set;
> +	err = devm_led_classdev_register(&pdev->dev, &led->led);
> +	if (err) {
> +		dev_err(led->dev, "Couldn't register led: %d", err);
> +		return err;
> +	}
> +
> +	if (led->info->init_mask) {
> +		err = regmap_update_bits(led->regmap, led->info->reg,
> +			led->info->init_mask, led->info->init_val);
> +		if (err) {
> +			dev_err(led->dev, "regmap failed: %d", err);
> +			return err;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static struct platform_driver cpcap_led_driver = {
> +	.probe = cpcap_led_probe,
> +	.driver = {
> +		.name = "cpcap-led",
> +		.of_match_table = cpcap_led_of_match,
> +	},
> +};
> +module_platform_driver(cpcap_led_driver);
> +
> +MODULE_DESCRIPTION("CPCAP LED driver");
> +MODULE_AUTHOR("Sebastian Reichel <sre@...nel.org>");
> +MODULE_LICENSE("GPL");

Your copyright note claims "GPL v2".


-- 
Best regards,
Jacek Anaszewski

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