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Date: Mon, 16 Jan 2012 23:10:55 +0100
From: Lars-Peter Clausen <lars@...afoo.de>
To: Peter Meerwald <pmeerw@...erw.net>
CC: linux-kernel@...r.kernel.org, rpurdie@...ys.net,
akpm@...ux-foundation.org
Subject: Re: [PATCH] leds: add driver for PCA9663 I2C chip
On 01/16/2012 10:04 PM, Peter Meerwald wrote:
> From: Peter Meerwald <p.meerwald@...-electronic.com>
>
> simple driver for the PCA9633 I2C chip supporting four LEDs and
> 255 brightness levels
Looks good, just a few minor issues.
>
> ---
> drivers/leds/Kconfig | 8 ++
> drivers/leds/Makefile | 1 +
> drivers/leds/leds-pca9633.c | 219 +++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 228 insertions(+), 0 deletions(-)
> create mode 100644 drivers/leds/leds-pca9633.c
> [...]
> diff --git a/drivers/leds/leds-pca9633.c b/drivers/leds/leds-pca9633.c
> new file mode 100644
> index 0000000..68c30d7
> --- /dev/null
> +++ b/drivers/leds/leds-pca9633.c
> @@ -0,0 +1,219 @@
> +/*
> + * Copyright 2011 bct electronic GmbH
> + *
> + * Author: Peter Meerwald <p.meerwald@...-electronic.com>
> + *
> + * Based on leds-pca955x.c
> + *
> + * This file is subject to the terms and conditions of version 2 of
> + * the GNU General Public License. See the file COPYING in the main
> + * directory of this archive for more details.
> + *
> + * LED driver for the PCA9633 I2C LED driver (7-bit slave address 0x62)
> + *
> + */
> +
> +#include <linux/module.h>
> +#include <linux/delay.h>
> +#include <linux/string.h>
> +#include <linux/ctype.h>
> +#include <linux/leds.h>
> +#include <linux/err.h>
> +#include <linux/i2c.h>
> +#include <linux/workqueue.h>
> +#include <linux/slab.h>
> +
> +/* LED select registers determine the source that drives LED outputs */
> +#define PCA9633_LED_OFF 0x0 /* LED driver off */
> +#define PCA9633_LED_ON 0x1 /* LED driver on */
> +#define PCA9633_LED_PWM 0x2 /* Controlled through PWM */
> +#define PCA9633_LED_GRP_PWM 0x3 /* Controlled through PWM/GRPPWM */
> +
> +#define PCA9633_MODE1 0x00
> +#define PCA9633_MODE2 0x01
> +#define PCA9633_PWM_BASE 0x02
> +#define PCA9633_LEDOUT 0x08
> +
> +static const struct i2c_device_id pca9633_id[] = {
> + { "pca9633", 0 },
> + { }
> +};
> +MODULE_DEVICE_TABLE(i2c, pca9633_id);
> +
> +struct pca9633_led {
> + struct i2c_client *client;
> + struct work_struct work;
> + spinlock_t lock;
> + enum led_brightness brightness;
> + struct led_classdev led_cdev;
> + int led_num; /* 0 .. 3 potentially */
> + char name[32];
> +};
> +
> +static void pca9633_led_work(struct work_struct *work)
> +{
> + struct pca9633_led *pca9633 = container_of(work,
> + struct pca9633_led, work);
> +
> + u8 ledout = i2c_smbus_read_byte_data(pca9633->client, PCA9633_LEDOUT);
> + int shift = 2 * pca9633->led_num;
> + u8 mask = 0x3 << shift;
> +
> + switch (pca9633->brightness) {
Using led_cdev.brightness should work as well.
> + case LED_FULL:
> + i2c_smbus_write_byte_data(pca9633->client, PCA9633_LEDOUT,
> + (ledout & ~mask) | (PCA9633_LED_ON << shift));
> + break;
> + case LED_OFF:
> + i2c_smbus_write_byte_data(pca9633->client, PCA9633_LEDOUT,
> + ledout & ~mask);
> + break;
> + default:
> + i2c_smbus_write_byte_data(pca9633->client,
> + PCA9633_PWM_BASE + pca9633->led_num,
> + pca9633->brightness);
> + i2c_smbus_write_byte_data(pca9633->client, PCA9633_LEDOUT,
> + (ledout & ~mask) | (PCA9633_LED_PWM << shift));
> + break;
> + }
> +}
> +
> +static void pca9633_led_set(struct led_classdev *led_cdev,
> + enum led_brightness value)
> +{
> + struct pca9633_led *pca9633;
> +
> + pca9633 = container_of(led_cdev, struct pca9633_led, led_cdev);
> +
> + spin_lock(&pca9633->lock);
Does the spinlock actually protect against anything?
> + pca9633->brightness = value;
> +
> + /*
> + * Must use workqueue for the actual I/O since I2C operations
> + * can sleep.
> + */
> + schedule_work(&pca9633->work);
> +
> + spin_unlock(&pca9633->lock);
> +}
> +
> +static int __devinit pca9633_probe(struct i2c_client *client,
> + const struct i2c_device_id *id)
> +{
> + struct pca9633_led *pca9633;
> + struct i2c_adapter *adapter;
> + struct led_platform_data *pdata;
> + int i, err;
> +
> + adapter = to_i2c_adapter(client->dev.parent);
> + pdata = client->dev.platform_data;
> +
> + printk(KERN_INFO "leds-pca9633: LED driver at slave address 0x%02x\n",
> + client->addr);
dev_info, but it probably wouldn't hurt either if the message is removed
altogether.
> +
> + if (!i2c_check_functionality(adapter, I2C_FUNC_I2C))
> + return -EIO;
You check for I2C functionality, but only ever use the smbus subset, which
should be supported by all adapters anyway, so you should be safe even without
the check.
> +
> + if (pdata) {
> + if (pdata->num_leds <= 0 || pdata->num_leds > 4) {
> + dev_err(&client->dev, "board info must claim at most 4 LEDs");
> + return -ENODEV;
-EINVAL?
> + }
> + }
> +
> + pca9633 = kzalloc(sizeof(*pca9633) * 4, GFP_KERNEL);
> + if (!pca9633)
> + return -ENOMEM;
> +
> + i2c_set_clientdata(client, pca9633);
> +
> + for (i = 0; i < 4; i++) {
> + pca9633[i].client = client;
> + pca9633[i].led_num = i;
> +
> + /* Platform data can specify LED names and default triggers */
> + if (pdata && i < pdata->num_leds) {
> + if (pdata->leds[i].name)
> + snprintf(pca9633[i].name,
> + sizeof(pca9633[i].name), "pca9633:%s",
> + pdata->leds[i].name);
Why the prefix?
> + if (pdata->leds[i].default_trigger)
> + pca9633[i].led_cdev.default_trigger =
> + pdata->leds[i].default_trigger;
> + } else {
> + snprintf(pca9633[i].name, sizeof(pca9633[i].name),
> + "pca9633:%d", i);
> + }
> +
> + spin_lock_init(&pca9633[i].lock);
> +
> + pca9633[i].led_cdev.name = pca9633[i].name;
> + pca9633[i].led_cdev.brightness_set = pca9633_led_set;
> +
> + INIT_WORK(&pca9633[i].work, pca9633_led_work);
> +
> + err = led_classdev_register(&client->dev, &pca9633[i].led_cdev);
> + if (err < 0)
> + goto exit;
> + }
> +
> + /* Disable LED all-call address and set normal mode */
> + i2c_smbus_write_byte_data(client, PCA9633_MODE1, 0x00);
> +
> + /* Turn off LEDs */
> + i2c_smbus_write_byte_data(client, PCA9633_LEDOUT, 0x00);
> +
> + return 0;
> +
> +exit:
> + while (i--) {
> + led_classdev_unregister(&pca9633[i].led_cdev);
> + cancel_work_sync(&pca9633[i].work);
> + }
> +
> + kfree(pca9633);
> +
> + return err;
> +}
> +
>[...]
> +
> +static int __init pca9633_leds_init(void)
> +{
> + return i2c_add_driver(&pca9633_driver);
> +}
> +
> +static void __exit pca9633_leds_exit(void)
> +{
> + i2c_del_driver(&pca9633_driver);
> +}
> +
> +module_init(pca9633_leds_init);
> +module_exit(pca9633_leds_exit);
Use the new module_i2c_driver macro.
--
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