From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mout-p-202.mailbox.org (mout-p-202.mailbox.org [80.241.56.172]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A18712FFFA4; Mon, 10 Nov 2025 11:55:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=80.241.56.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762775713; cv=none; b=lKxuPR/1qHl6yzT1xGpp8T6WsorJLkdt+u9+xrrG088TDOw4KImcxbRkkfyRqQBf8e3tAFQOL+s8Ja1iB/wqKqNLMW0Hlnbsb65qz3PPw6/obGsznLmfyjm+Ly4tLalLIbDcEDaK1tf3hc5AnGkPOuSinASE6wiC8X4CVPzGdMI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762775713; c=relaxed/simple; bh=SEGGQCraDKkaakuOL1qELKnn7n3IsPKHAFteZ3/gqQE=; h=Message-ID:Date:MIME-Version:From:Subject:To:References: In-Reply-To:Content-Type; b=RTn1t05AON/qaID7nP0bnNIunov7Bg0NMzloZXYZZE4GwTaxpiEpeUZQSf6eJNPbY3Wp9dEJd0FtC9jDELyDwXzynuM47Y6smptz+gYm7kD31TnImur8TorWHfFhEU3Eh2JfOevpjFKibovdJOfo361/9Xf6LngQP0OYqU7/Vf4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=timmermann.space; spf=pass smtp.mailfrom=timmermann.space; arc=none smtp.client-ip=80.241.56.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=timmermann.space Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=timmermann.space Received: from smtp202.mailbox.org (smtp202.mailbox.org [10.196.197.202]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-202.mailbox.org (Postfix) with ESMTPS id 4d4p4m4JkWz9t8S; Mon, 10 Nov 2025 12:55:04 +0100 (CET) Message-ID: Date: Mon, 10 Nov 2025 12:55:02 +0100 Precedence: bulk X-Mailing-List: devicetree@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Lukas Timmermann Subject: Re: [PATCH v9 2/2] leds: as3668: Driver for the ams Osram 4-channel i2c LED driver To: pavel@kernel.org, robh@kernel.org, krzk+dt@kernel.org, conor+dt@kernel.org, linux-leds@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org References: <20251014152604.852487-1-linux@timmermann.space> <20251014152604.852487-3-linux@timmermann.space> <20251023141844.GP475031@google.com> Content-Language: en-US, de-DE In-Reply-To: <20251023141844.GP475031@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Am 23.10.25 um 16:18 schrieb Lee Jones: > On Tue, 14 Oct 2025, Lukas Timmermann wrote: > >> Since there were no existing drivers for the AS3668 or related devices, >> a new driver was introduced in a separate file. Similar devices were >> reviewed, but none shared enough characteristics to justify code reuse. >> As a result, this driver is written specifically for the AS3668. >> >> Signed-off-by: Lukas Timmermann >> --- >> MAINTAINERS | 1 + >> drivers/leds/Kconfig | 13 +++ >> drivers/leds/Makefile | 1 + >> drivers/leds/leds-as3668.c | 188 +++++++++++++++++++++++++++++++++++++ >> 4 files changed, 203 insertions(+) >> create mode 100644 drivers/leds/leds-as3668.c >> >> diff --git a/MAINTAINERS b/MAINTAINERS >> index 091206c54c63..945d78fef380 100644 >> --- a/MAINTAINERS >> +++ b/MAINTAINERS >> @@ -3511,6 +3511,7 @@ M: Lukas Timmermann >> L: linux-leds@vger.kernel.org >> S: Maintained >> F: Documentation/devicetree/bindings/leds/ams,as3668.yaml >> +F: drivers/leds/leds-as3668.c >> >> ASAHI KASEI AK7375 LENS VOICE COIL DRIVER >> M: Tianshu Qiu >> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig >> index a104cbb0a001..8cfb423ddf82 100644 >> --- a/drivers/leds/Kconfig >> +++ b/drivers/leds/Kconfig >> @@ -100,6 +100,19 @@ config LEDS_ARIEL >> >> Say Y to if your machine is a Dell Wyse 3020 thin client. >> >> +config LEDS_AS3668 > > LEDS_OSRAM_AMS_AS3668 > >> + tristate "LED support for AMS AS3668" > > "Osram" Thanks. Makes sense. >> + depends on LEDS_CLASS >> + depends on I2C >> + help >> + This option enables support for the AMS AS3668 LED controller. > > "Osram" Same.>> + The AS3668 provides up to four LED channels and is controlled via >> + the I2C bus. This driver offers basic brightness control for each >> + channel, without support for blinking or other advanced features. >> + >> + To compile this driver as a module, choose M here: the module >> + will be called leds-as3668. >> + >> config LEDS_AW200XX >> tristate "LED support for Awinic AW20036/AW20054/AW20072/AW20108" >> depends on LEDS_CLASS >> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile >> index 2f170d69dcbf..983811384fec 100644 >> --- a/drivers/leds/Makefile >> +++ b/drivers/leds/Makefile >> @@ -14,6 +14,7 @@ obj-$(CONFIG_LEDS_ADP5520) += leds-adp5520.o >> obj-$(CONFIG_LEDS_AN30259A) += leds-an30259a.o >> obj-$(CONFIG_LEDS_APU) += leds-apu.o >> obj-$(CONFIG_LEDS_ARIEL) += leds-ariel.o >> +obj-$(CONFIG_LEDS_AS3668) += leds-as3668.o >> obj-$(CONFIG_LEDS_AW200XX) += leds-aw200xx.o >> obj-$(CONFIG_LEDS_AW2013) += leds-aw2013.o >> obj-$(CONFIG_LEDS_BCM6328) += leds-bcm6328.o >> diff --git a/drivers/leds/leds-as3668.c b/drivers/leds/leds-as3668.c >> new file mode 100644 >> index 000000000000..2b7b776fe2f5 >> --- /dev/null >> +++ b/drivers/leds/leds-as3668.c >> @@ -0,0 +1,188 @@ >> +// SPDX-License-Identifier: GPL-2.0-or-later >> +/* >> + * Osram AMS AS3668 LED Driver IC >> + * >> + * Copyright (C) 2025 Lukas Timmermann >> + */ >> + >> +#include >> +#include >> +#include >> +#include >> +#include >> + >> +#define AS3668_MAX_LEDS 4 >> +#define AS3668_EXPECTED_I2C_ADDR 0x42 >> + >> +/* Chip Ident */ >> + >> +#define AS3668_CHIP_ID1_REG 0x3e >> +#define AS3668_CHIP_ID 0xa5 >> + >> +/* Current Control */ >> + >> +#define AS3668_CURRX_CONTROL_REG 0x01 >> +#define AS3668_CURR1_REG 0x02 >> +#define AS3668_CURR2_REG 0x03 >> +#define AS3668_CURR3_REG 0x04 >> +#define AS3668_CURR4_REG 0x05 >> +#define AS3668_CURRX_MODE_ON 0x1 >> +#define AS3668_CURRX_CURR1_MASK GENMASK(1, 0) >> +#define AS3668_CURRX_CURR2_MASK GENMASK(3, 2) >> +#define AS3668_CURRX_CURR3_MASK GENMASK(5, 4) >> +#define AS3668_CURRX_CURR4_MASK GENMASK(7, 6) >> + >> +struct as3668_led { >> + struct led_classdev cdev; >> + struct as3668 *chip; >> + struct fwnode_handle *fwnode; >> + int led_id; >> +}; >> + >> +struct as3668 { >> + struct i2c_client *client; >> + struct as3668_led leds[AS3668_MAX_LEDS]; >> +}; >> + >> +static enum led_brightness as3668_brightness_get(struct led_classdev *cdev) >> +{ >> + struct as3668_led *led = container_of(cdev, struct as3668_led, cdev); >> + >> + return i2c_smbus_read_byte_data(led->chip->client, AS3668_CURR1_REG + led->led_id); >> +} >> + >> +static void as3668_brightness_set(struct led_classdev *cdev, enum led_brightness brightness) >> +{ >> + struct as3668_led *led = container_of(cdev, struct as3668_led, cdev); >> + >> + int err = i2c_smbus_write_byte_data(led->chip->client, >> + AS3668_CURR1_REG + led->led_id, >> + brightness); >> + >> + if (err) >> + dev_err(&led->chip->client->dev, "error writing to reg 0x%02x, returned %d\n", > > The user isn't going to care about this stuff. > > "Failed to set brightness: %d" > >> + AS3668_CURR1_REG + led->led_id, err); >> +} >> + >> +static int as3668_dt_init(struct as3668 *as3668) >> +{ >> + struct device *dev = &as3668->client->dev; >> + struct as3668_led *led; >> + struct led_init_data init_data = {}; >> + int err; >> + u32 reg; >> + >> + for_each_available_child_of_node_scoped(dev_of_node(dev), child) { >> + err = of_property_read_u32(child, "reg", ®); >> + if (err) >> + return dev_err_probe(dev, err, "'reg' property missing from %s\n", > > "Failed to read 'reg' property" > Thanks >> + child->name); >> + >> + if (reg < 0 || reg > AS3668_MAX_LEDS) >> + return dev_err_probe(dev, -EOPNOTSUPP, >> + "'reg' property in %s is out of scope: %d\n", > > "Unsupported LED: %d" > I understand now that should be user facing messages... Thanks. >> + child->name, reg); >> + >> + led = &as3668->leds[reg]; >> + led->fwnode = of_fwnode_handle(child); >> + >> + led->led_id = reg; >> + led->chip = as3668; >> + >> + led->cdev.max_brightness = U8_MAX; >> + led->cdev.brightness_get = as3668_brightness_get; >> + led->cdev.brightness_set = as3668_brightness_set; >> + >> + init_data.fwnode = led->fwnode; >> + init_data.default_label = ":"; >> + >> + err = devm_led_classdev_register_ext(dev, &led->cdev, &init_data); >> + if (err) >> + return dev_err_probe(dev, err, "failed to register LED %d\n", reg); >> + } >> + >> + return 0; >> +} >> + >> +static int as3668_probe(struct i2c_client *client) >> +{ >> + struct as3668 *as3668; >> + int err; >> + u8 chip_id; >> + >> + if (client->addr != AS3668_EXPECTED_I2C_ADDR) > > Expected is weird. > > Why are we trying to catch-out the consumer? > > If you already know what the I2C address is, just use that. > Okay, I will do that instead. I aim to fail early in my code and double check everything. Drivers shouldn't error check the device tree, if I understand you correctly. >> + return dev_err_probe(&client->dev, -EFAULT, >> + "expected i2c address 0x%02x, got 0x%02x\n", >> + AS3668_EXPECTED_I2C_ADDR, client->addr); >> + >> + /* Read identifier from chip */ > > This comment is superfluous IMHO. > > The register name should tell us everything. > >> + chip_id = i2c_smbus_read_byte_data(client, AS3668_CHIP_ID1_REG); >> + > > Remove this line. > >> + if (chip_id != AS3668_CHIP_ID) >> + return dev_err_probe(&client->dev, -ENODEV, >> + "expected chip id 0x%02x, got 0x%02x\n", > > "ID" > >> + AS3668_CHIP_ID, chip_id); >> + >> + as3668 = devm_kzalloc(&client->dev, sizeof(*as3668), GFP_KERNEL); >> + if (!as3668) >> + return -ENOMEM; >> + >> + as3668->client = client; >> + >> + err = as3668_dt_init(as3668); >> + if (err) >> + return err; >> + >> + /* Set all four channel modes to 'on' */ > > Even if a specific LED wasn't requested? > > Are you sure that this doesn't have any drawbacks (power perhaps)? > After reading through downstream code and it's datasheet, this actually might result in higher power consumption than switching it off. I suppose we could enable and disable a specific channel when setting the brightness. I will add that in my next patch version. >> + err = i2c_smbus_write_byte_data(client, AS3668_CURRX_CONTROL_REG, >> + FIELD_PREP(AS3668_CURRX_CURR1_MASK, AS3668_CURRX_MODE_ON) | >> + FIELD_PREP(AS3668_CURRX_CURR2_MASK, AS3668_CURRX_MODE_ON) | >> + FIELD_PREP(AS3668_CURRX_CURR3_MASK, AS3668_CURRX_MODE_ON) | >> + FIELD_PREP(AS3668_CURRX_CURR4_MASK, AS3668_CURRX_MODE_ON)); >> + >> + /* Set initial currents to 0mA */ >> + err |= i2c_smbus_write_byte_data(client, AS3668_CURR1_REG, 0); >> + err |= i2c_smbus_write_byte_data(client, AS3668_CURR2_REG, 0); >> + err |= i2c_smbus_write_byte_data(client, AS3668_CURR3_REG, 0); >> + err |= i2c_smbus_write_byte_data(client, AS3668_CURR4_REG, 0); >> + >> + if (err) >> + return dev_err_probe(&client->dev, -EIO, "failed to write to the device\n"); >> + >> + return 0; >> +} >> + >> +static void as3668_remove(struct i2c_client *client) >> +{ >> + int err; > > '\n' here. > Okay >> + err = i2c_smbus_write_byte_data(client, AS3668_CURRX_CONTROL_REG, 0); >> + if (err) >> + dev_err(&client->dev, "couldn't remove the device\n"); > > This does not remove the device. > > "Failed to turn off the LEDs" > Obviously, now that I see it. Thanks >> +} >> + >> +static const struct i2c_device_id as3668_idtable[] = { >> + { "as3668" }, >> + { } >> +}; >> +MODULE_DEVICE_TABLE(i2c, as3668_idtable); >> + >> +static const struct of_device_id as3668_match_table[] = { >> + { .compatible = "ams,as3668" }, >> + { } >> +}; >> +MODULE_DEVICE_TABLE(of, as3668_match_table); >> + >> +static struct i2c_driver as3668_driver = { >> + .driver = { >> + .name = "leds_as3668", >> + .of_match_table = as3668_match_table, >> + }, >> + .probe = as3668_probe, >> + .remove = as3668_remove, >> + .id_table = as3668_idtable, >> +}; >> +module_i2c_driver(as3668_driver); >> + >> +MODULE_AUTHOR("Lukas Timmermann "); >> +MODULE_DESCRIPTION("AS3668 LED driver"); >> +MODULE_LICENSE("GPL"); >> -- >> 2.51.0 >> >