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Date: Mon, 27 Jun 2016 10:54:47 +0200
From: Florian Vaussard <florian.vaussard@...g-vd.ch>
To: Jacek Anaszewski <j.anaszewski@...sung.com>,
Florian Vaussard <florian.vaussard@...il.com>
CC: <devicetree@...r.kernel.org>, Richard Purdie <rpurdie@...ys.net>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Pavel Machek <pavel@....cz>, <linux-leds@...r.kernel.org>,
<linux-kernel@...r.kernel.org>,
Vaussard Florian <florian.vaussard@...g-vd.ch>
Subject: Re: [PATCH v2 2/2] leds: Add driver for NCP5623 3-channel I2C LED
driver
Hi Jacek,
Le 27. 06. 16 à 10:14, Jacek Anaszewski a écrit :
> Hi Florian,
>
> Thanks for the update. I have few comments below.
>
> On 06/27/2016 09:03 AM, Florian Vaussard wrote:
>> The NCP5623 is a 3-channel LED driver from On Semiconductor controlled
>> through I2C. The PWM of each channel can be independently set with 32
>> distinct levels. In addition, the intensity of the current source can be
>> globally set using an external bias resistor fixing the reference
>> current (Iref) and a dedicated register (ILED), following the
>> relationship:
>>
>> I = 2400*Iref/(31-ILED)
>>
>> with Iref = Vref/Rbias, and Vref = 0.6V.
>>
>> Signed-off-by: Florian Vaussard <florian.vaussard@...g-vd.ch>
>> ---
>> drivers/leds/Kconfig | 11 ++
>> drivers/leds/Makefile | 1 +
>> drivers/leds/leds-ncp5623.c | 269 ++++++++++++++++++++++++++++++++++++++++++++
>> 3 files changed, 281 insertions(+)
>> create mode 100644 drivers/leds/leds-ncp5623.c
>>
>> diff --git a/drivers/leds/Kconfig b/drivers/leds/Kconfig
>> index 5ae2834..6d3e44d 100644
>> --- a/drivers/leds/Kconfig
>> +++ b/drivers/leds/Kconfig
>> @@ -588,6 +588,17 @@ config LEDS_BLINKM
>> This option enables support for the BlinkM RGB LED connected
>> through I2C. Say Y to enable support for the BlinkM LED.
>>
>> +config LEDS_NCP5623
>> + tristate "LED Support for NCP5623 I2C chip"
>> + depends on LEDS_CLASS
>> + depends on I2C
>> + help
>> + This option enables support for LEDs connected to NCP5623
>> + LED driver chips accessed via the I2C bus.
>> + Driver supports brightness control.
>> +
>> + Say Y to enable this driver.
>> +
>> config LEDS_POWERNV
>> tristate "LED support for PowerNV Platform"
>> depends on LEDS_CLASS
>> diff --git a/drivers/leds/Makefile b/drivers/leds/Makefile
>> index cb2013d..a2f0e10 100644
>> --- a/drivers/leds/Makefile
>> +++ b/drivers/leds/Makefile
>> @@ -67,6 +67,7 @@ obj-$(CONFIG_LEDS_KTD2692) += leds-ktd2692.o
>> obj-$(CONFIG_LEDS_POWERNV) += leds-powernv.o
>> obj-$(CONFIG_LEDS_SEAD3) += leds-sead3.o
>> obj-$(CONFIG_LEDS_IS31FL32XX) += leds-is31fl32xx.o
>> +obj-$(CONFIG_LEDS_NCP5623) += leds-ncp5623.o
>>
>> # LED SPI Drivers
>> obj-$(CONFIG_LEDS_DAC124S085) += leds-dac124s085.o
>> diff --git a/drivers/leds/leds-ncp5623.c b/drivers/leds/leds-ncp5623.c
>> new file mode 100644
>> index 0000000..6e4c969
>> --- /dev/null
>> +++ b/drivers/leds/leds-ncp5623.c
>> @@ -0,0 +1,269 @@
>> +/*
>> + * Copyright 2016 Florian Vaussard <florian.vaussard@...g-vd.ch>
>> + *
>> + * Based on leds-tlc591xx.c
>> + *
>> + * This program is free software; you can redistribute it and/or modify
>> + * it under the terms of the GNU General Public License as published by
>> + * the Free Software Foundation; version 2 of the License.
>> + */
>> +
>> +#include <linux/bitops.h>
>> +#include <linux/i2c.h>
>> +#include <linux/kernel.h>
>> +#include <linux/leds.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/slab.h>
>> +
>> +#define NCP5623_MAX_LEDS 3
>> +#define NCP5623_MAX_STEPS 31
>> +#define NCP5623_MAX_CURRENT 31
>> +#define NCP5623_MAX_CURRENT_UA 30000
>> +
>> +#define NCP5623_CMD_SHIFT 5
>> +#define CMD_SHUTDOWN (0x00 << NCP5623_CMD_SHIFT)
>> +#define CMD_ILED (0x01 << NCP5623_CMD_SHIFT)
>> +#define CMD_PWM1 (0x02 << NCP5623_CMD_SHIFT)
>> +#define CMD_PWM2 (0x03 << NCP5623_CMD_SHIFT)
>> +#define CMD_PWM3 (0x04 << NCP5623_CMD_SHIFT)
>> +#define CMD_UPWARD_DIM (0x05 << NCP5623_CMD_SHIFT)
>> +#define CMD_DOWNWARD_DIM (0x06 << NCP5623_CMD_SHIFT)
>> +#define CMD_DIM_STEP (0x07 << NCP5623_CMD_SHIFT)
>> +
>> +#define LED_to_CMD(led) ((0x02 + led) << NCP5623_CMD_SHIFT)
>
> Please use only capital letters in the macro name.
>
>> +
>> +#define NCP5623_DATA_MASK GENMASK(NCP5623_CMD_SHIFT - 1, 0)
>> +#define NCP5623_CMD(cmd, data) (cmd | (data & NCP5623_DATA_MASK))
>> +
>> +struct ncp5623_led {
>> + bool active;
>> + unsigned int led_no;
>> + u32 led_max_current;
>> + struct led_classdev ldev;
>> + struct ncp5623_priv *priv;
>> +};
>> +
>> +struct ncp5623_priv {
>> + struct ncp5623_led leds[NCP5623_MAX_LEDS];
>> + u32 led_iref;
>> + u32 leds_max_current;
>> + struct i2c_client *client;
>> +};
>> +
>> +static struct ncp5623_led *ldev_to_led(struct led_classdev *ldev)
>> +{
>> + return container_of(ldev, struct ncp5623_led, ldev);
>> +}
>> +
>> +static int ncp5623_send_cmd(struct ncp5623_priv *priv, u8 cmd, u8 data)
>> +{
>> + char cmd_data[1] = { NCP5623_CMD(cmd, data) };
>> + int err;
>> +
>> + err = i2c_master_send(priv->client, cmd_data, ARRAY_SIZE(cmd_data));
>> +
>> + return (err < 0 ? err : 0);
>> +}
>> +
>> +static int ncp5623_set_pwm(struct ncp5623_led *led, u8 brightness)
>> +{
>> + struct ncp5623_priv *priv = led->priv;
>> + u8 cmd;
>
> cmd is redundant here, you can pass the macro directly.
>
>> +
>> + cmd = LED_to_CMD(led->led_no);
>> +
>> + return ncp5623_send_cmd(priv, cmd, brightness);
>
> How about just one line:
>
> return ncp5623_send_cmd(led->priv, LED_TO_CMD(led->led_no), brightness);
>
Ok why not. As it is used only by ncp5623_brightness_set(), does it make sense
to keep this function after all?
>> +}
>> +
>> +static int ncp5623_brightness_set(struct led_classdev *led_cdev,
>> + enum led_brightness brightness)
>> +{
>> + struct ncp5623_led *led = ldev_to_led(led_cdev);
>> +
>> + return ncp5623_set_pwm(led, brightness);
>
> return ncp5623_set_pwm(ldev_to_led(led_cdev), brightness);
>
Here I am a bit less enthusiast as I find the result less readable. But I am not
strongly against it neither.
>> +}
>> +
>> +static void ncp5623_destroy_devices(struct ncp5623_priv *priv)
>> +{
>> + struct ncp5623_led *led;
>> + int i;
>> +
>> + for (i = 0; i < NCP5623_MAX_LEDS; i++) {
>> + led = &priv->leds[i];
>> + if (led->active) {
>> + led_classdev_unregister(&led->ldev);
>> + led->active = false;
>> + }
>> + }
>> +}
>
> This function is redundant when using devm_led_classdev_register().
>
Indeed.
>> +
>> +static int ncp5623_configure(struct device *dev,
>> + struct ncp5623_priv *priv)
>> +{
>> + unsigned int i;
>> + unsigned int n;
>> + struct ncp5623_led *led;
>> + int effective_current;
>> + int err;
>> +
>> + /* Setup the internal current source, round down */
>> + n = 2400 * priv->led_iref / priv->leds_max_current + 1;
>> + if (n > NCP5623_MAX_CURRENT)
>> + n = NCP5623_MAX_CURRENT;
>> +
>> + effective_current = 2400 * priv->led_iref / n;
>> + dev_dbg(dev, "setting maximum current to %u uA\n", effective_current);
>> +
>> + err = ncp5623_send_cmd(priv, CMD_ILED, NCP5623_MAX_CURRENT - n);
>> + if (err < 0) {
>> + dev_err(dev, "cannot set the current\n");
>> + return err;
>> + }
>> +
>> + /* Setup each individual LED */
>> + for (i = 0; i < NCP5623_MAX_LEDS; i++) {
>> + led = &priv->leds[i];
>> +
>> + if (!led->active)
>> + continue;
>> +
>> + led->priv = priv;
>> + led->led_no = i;
>> + led->ldev.brightness_set_blocking = ncp5623_brightness_set;
>> +
>> + led->ldev.max_brightness = led->led_max_current *
>> + NCP5623_MAX_STEPS / effective_current;
>> + if (led->ldev.max_brightness > NCP5623_MAX_STEPS)
>> + led->ldev.max_brightness = NCP5623_MAX_STEPS;
>> +
>> + err = devm_led_classdev_register(dev, &led->ldev);
>> + if (err < 0) {
>> + dev_err(dev, "couldn't register LED %s\n",
>> + led->ldev.name);
>> + goto exit;
>> + }
>> + }
>> +
>> + return 0;
>> +
>> +exit:
>> + ncp5623_destroy_devices(priv);
>> + return err;
>> +}
>> +
>> +static int ncp5623_parse_dt(struct ncp5623_priv *priv, struct device_node *np)
>> +{
>> + struct device_node *child;
>> + struct ncp5623_led *led;
>> + u32 reg;
>> + int count;
>> + int err;
>> +
>> + err = of_property_read_u32(np, "onnn,led-iref-microamp",
>> + &priv->led_iref);
>> + if (err)
>> + return -EINVAL;
>> +
>> + priv->leds_max_current = 0;
>
> priv is allocated with kzalloc, so this is redundant.
>
>> +
>> + count = of_get_child_count(np);
>> + if (!count || count > NCP5623_MAX_LEDS)
>> + return -EINVAL;
>> +
>> + for_each_child_of_node(np, child) {
>> + err = of_property_read_u32(child, "reg", ®);
>> + if (err)
>> + return err;
>
> Empty line here please.
>
>> + if (reg < 0 || reg >= NCP5623_MAX_LEDS) {
>> + err = -EINVAL;
>> + goto dt_child_parse_error;
>> + }
>> +
>> + led = &priv->leds[reg];
>> + if (led->active) {
>> + err = -EINVAL;
>> + goto dt_child_parse_error;
>> + }
>> +
>> + led->active = true;
>
> Is the 'active' property really needed? You could verify if the LED
> has been already initialized e.g. by checking led->ldev.name for
> being NULL.
>
This is also an option, but I find
if (led->ldev.name != NULL) {
/* error */
...
}
less clear about the purpose of the test.
>> +
>> + err = of_property_read_u32(child, "led-max-microamp",
>> + &led->led_max_current);
>> + if (err || led->led_max_current > NCP5623_MAX_CURRENT_UA)
>> + return -EINVAL;
>> + if (led->led_max_current > priv->leds_max_current)
>> + priv->leds_max_current = led->led_max_current;
>> +
>> + led->ldev.name =
>> + of_get_property(child, "label", NULL) ? : child->name;
>> + led->ldev.default_trigger =
>> + of_get_property(child, "linux,default-trigger", NULL);
>> + }
>> +
>> + return 0;
>> +
>> +dt_child_parse_error:
>> + of_node_put(child);
>> +
>> + return err;
>> +}
>> +
>> +static const struct of_device_id ncp5623_of_match[] = {
>> + { .compatible = "onnn,ncp5623" },
>> + { /* sentinel */ },
>> +};
>> +MODULE_DEVICE_TABLE(of, ncp5623_of_match);
>> +
>> +static int ncp5623_probe(struct i2c_client *client,
>> + const struct i2c_device_id *id)
>> +{
>> + struct device *dev = &client->dev;
>> + struct device_node *np = dev->of_node;
>> + struct ncp5623_priv *priv;
>> + int err;
>> +
>> + priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
>> + if (!priv)
>> + return -ENOMEM;
>> +
>> + priv->client = client;
>> + i2c_set_clientdata(client, priv);
>> +
>> + err = ncp5623_parse_dt(priv, np);
>> + if (err)
>> + return err;
>> +
>> + return ncp5623_configure(dev, priv);
>> +}
>> +
>> +static int ncp5623_remove(struct i2c_client *client)
>> +{
>> + struct ncp5623_priv *priv = i2c_get_clientdata(client);
>> +
>> + ncp5623_destroy_devices(priv);
>> +
>> + return 0;
>> +}
>
> remove callback is not needed with devm prefixed registration.
>
Thank you for the review!
Best,
Florian
>> +
>> +static const struct i2c_device_id ncp5623_id[] = {
>> + { "ncp5623" },
>> + {},
>> +};
>> +MODULE_DEVICE_TABLE(i2c, ncp5623_id);
>> +
>> +static struct i2c_driver ncp5623_driver = {
>> + .driver = {
>> + .name = "ncp5623",
>> + .of_match_table = of_match_ptr(ncp5623_of_match),
>> + },
>> + .probe = ncp5623_probe,
>> + .remove = ncp5623_remove,
>> + .id_table = ncp5623_id,
>> +};
>> +
>> +module_i2c_driver(ncp5623_driver);
>> +
>> +MODULE_AUTHOR("Florian Vaussard <florian.vaussard@...g-vd.ch>");
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_DESCRIPTION("NCP5623 LED driver");
>>
>
>
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