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Date: Mon, 27 Jun 2016 10:14:12 +0200
From: Jacek Anaszewski <j.anaszewski@...sung.com>
To: 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,
Florian Vaussard <florian.vaussard@...g-vd.ch>
Subject: Re: [PATCH v2 2/2] leds: Add driver for NCP5623 3-channel I2C LED
driver
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);
> +}
> +
> +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);
> +}
> +
> +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().
> +
> +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.
> +
> + 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.
> +
> +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");
>
--
Best regards,
Jacek Anaszewski
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