- 根目录:
- drivers
- leds
- leds-lp3944.c
/*
* leds-lp3944.c - driver for National Semiconductor LP3944 Funlight Chip
*
* Copyright (C) 2009 Antonio Ospite <ospite@studenti.unina.it>
*
* 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.
*
*/
/*
* I2C driver for National Semiconductor LP3944 Funlight Chip
* http://www.national.com/pf/LP/LP3944.html
*
* This helper chip can drive up to 8 leds, with two programmable DIM modes;
* it could even be used as a gpio expander but this driver assumes it is used
* as a led controller.
*
* The DIM modes are used to set _blink_ patterns for leds, the pattern is
* specified supplying two parameters:
* - period: from 0s to 1.6s
* - duty cycle: percentage of the period the led is on, from 0 to 100
*
* LP3944 can be found on Motorola A910 smartphone, where it drives the rgb
* leds, the camera flash light and the displays backlights.
*/
#include <linux/module.h>
#include <linux/i2c.h>
#include <linux/slab.h>
#include <linux/leds.h>
#include <linux/mutex.h>
#include <linux/workqueue.h>
#include <linux/leds-lp3944.h>
/* Read Only Registers */
#define LP3944_REG_INPUT1 0x00 /* LEDs 0-7 InputRegister (Read Only) */
#define LP3944_REG_REGISTER1 0x01 /* None (Read Only) */
#define LP3944_REG_PSC0 0x02 /* Frequency Prescaler 0 (R/W) */
#define LP3944_REG_PWM0 0x03 /* PWM Register 0 (R/W) */
#define LP3944_REG_PSC1 0x04 /* Frequency Prescaler 1 (R/W) */
#define LP3944_REG_PWM1 0x05 /* PWM Register 1 (R/W) */
#define LP3944_REG_LS0 0x06 /* LEDs 0-3 Selector (R/W) */
#define LP3944_REG_LS1 0x07 /* LEDs 4-7 Selector (R/W) */
/* These registers are not used to control leds in LP3944, they can store
* arbitrary values which the chip will ignore.
*/
#define LP3944_REG_REGISTER8 0x08
#define LP3944_REG_REGISTER9 0x09
#define LP3944_DIM0 0
#define LP3944_DIM1 1
/* period in ms */
#define LP3944_PERIOD_MIN 0
#define LP3944_PERIOD_MAX 1600
/* duty cycle is a percentage */
#define LP3944_DUTY_CYCLE_MIN 0
#define LP3944_DUTY_CYCLE_MAX 100
#define ldev_to_led(c) container_of(c, struct lp3944_led_data, ldev)
/* Saved data */
struct lp3944_led_data {
u8 id;
enum lp3944_type type;
enum lp3944_status status;
struct led_classdev ldev;
struct i2c_client *client;
struct work_struct work;
};
struct lp3944_data {
struct mutex lock;
struct i2c_client *client;
struct lp3944_led_data leds[LP3944_LEDS_MAX];
};
static int lp3944_reg_read(struct i2c_client *client, u8 reg, u8 *value)
{
int tmp;
tmp = i2c_smbus_read_byte_data(client, reg);
if (tmp < 0)
return tmp;
*value = tmp;
return 0;
}
static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value)
{
return i2c_smbus_write_byte_data(client, reg, value);
}
/**
* Set the period for DIM status
*
* @client: the i2c client
* @dim: either LP3944_DIM0 or LP3944_DIM1
* @period: period of a blink, that is a on/off cycle, expressed in ms.
*/
static int lp3944_dim_set_period(struct i2c_client *client, u8 dim, u16 period)
{
u8 psc_reg;
u8 psc_value;
int err;
if (dim == LP3944_DIM0)
psc_reg = LP3944_REG_PSC0;
else if (dim == LP3944_DIM1)
psc_reg = LP3944_REG_PSC1;
else
return -EINVAL;
/* Convert period to Prescaler value */
if (period > LP3944_PERIOD_MAX)
return -EINVAL;
psc_value = (period * 255) / LP3944_PERIOD_MAX;
err = lp3944_reg_write(client, psc_reg, psc_value);
return err;
}
/**
* Set the duty cycle for DIM status
*
* @client: the i2c client
* @dim: either LP3944_DIM0 or LP3944_DIM1
* @duty_cycle: percentage of a period during which a led is ON
*/
static int lp3944_dim_set_dutycycle(struct i2c_client *client, u8 dim,
u8 duty_cycle)
{
u8 pwm_reg;
u8 pwm_value;
int err;
if (dim == LP3944_DIM0)
pwm_reg = LP3944_REG_PWM0;
else if (dim == LP3944_DIM1)
pwm_reg = LP3944_REG_PWM1;
else
return -EINVAL;
/* Convert duty cycle to PWM value */
if (duty_cycle > LP3944_DUTY_CYCLE_MAX)
return -EINVAL;
pwm_value = (duty_cycle * 255) / LP3944_DUTY_CYCLE_MAX;
err = lp3944_reg_write(client, pwm_reg, pwm_value);
return err;
}
/**
* Set the led status
*
* @led: a lp3944_led_data structure
* @status: one of LP3944_LED_STATUS_OFF
* LP3944_LED_STATUS_ON
* LP3944_LED_STATUS_DIM0
* LP3944_LED_STATUS_DIM1
*/
static int lp3944_led_set(struct lp3944_led_data *led, u8 status)
{
struct lp3944_data *data = i2c_get_clientdata(led->client);
u8 id = led->id;
u8 reg;
u8 val = 0;
int err;
dev_dbg(&led->client->dev, "%s: %s, status before normalization:%d\n",
__func__, led->ldev.name, status);
switch (id) {
case LP3944_LED0:
case LP3944_LED1:
case LP3944_LED2:
case LP3944_LED3:
reg = LP3944_REG_LS0;
break;
case LP3944_LED4:
case LP3944_LED5:
case LP3944_LED6:
case LP3944_LED7:
id -= LP3944_LED4;
reg = LP3944_REG_LS1;
break;
default:
return -EINVAL;
}
if (status > LP3944_LED_STATUS_DIM1)
return -EINVAL;
/* invert only 0 and 1, leave unchanged the other values,
* remember we are abusing status to set blink patterns
*/
if (led->type == LP3944_LED_TYPE_LED_INVERTED && status < 2)
status = 1 - status;
mutex_lock(&data->lock);
lp3944_reg_read(led->client, reg, &val);
val &= ~(LP3944_LED_STATUS_MASK << (id << 1));
val |= (status << (id << 1));
dev_dbg(&led->client->dev, "%s: %s, reg:%d id:%d status:%d val:%#x\n",
__func__, led->ldev.name, reg, id, status, val);
/* set led status */
err = lp3944_reg_write(led->client, reg, val);
mutex_unlock(&data->lock);
return err;
}
static int lp3944_led_set_blink(struct led_classdev *led_cdev,
unsigned long *delay_on,
unsigned long *delay_off)
{
struct lp3944_led_data *led = ldev_to_led(led_cdev);
u16 period;
u8 duty_cycle;
int err;
/* units are in ms */
if (*delay_on + *delay_off > LP3944_PERIOD_MAX)
return -EINVAL;
if (*delay_on == 0 && *delay_off == 0) {
/* Special case: the leds subsystem requires a default user
* friendly blink pattern for the LED. Let's blink the led
* slowly (1Hz).
*/
*delay_on = 500;
*delay_off = 500;
}
period = (*delay_on) + (*delay_off);
/* duty_cycle is the percentage of period during which the led is ON */
duty_cycle = 100 * (*delay_on) / period;
/* invert duty cycle for inverted leds, this has the same effect of
* swapping delay_on and delay_off
*/
if (led->type == LP3944_LED_TYPE_LED_INVERTED)
duty_cycle = 100 - duty_cycle;
/* NOTE: using always the first DIM mode, this means that all leds
* will have the same blinking pattern.
*
* We could find a way later to have two leds blinking in hardware
* with different patterns at the same time, falling back to software
* control for the other ones.
*/
err = lp3944_dim_set_period(led->client, LP3944_DIM0, period);
if (err)
return err;
err = lp3944_dim_set_dutycycle(led->client, LP3944_DIM0, duty_cycle);
if (err)
return err;
dev_dbg(&led->client->dev, "%s: OK hardware accelerated blink!\n",
__func__);
led->status = LP3944_LED_STATUS_DIM0;
schedule_work(&led->work);
return 0;
}
static void lp3944_led_set_brightness(struct led_classdev *led_cdev,
enum led_brightness brightness)
{
struct lp3944_led_data *led = ldev_to_led(led_cdev);
dev_dbg(&led->client->dev, "%s: %s, %d\n",
__func__, led_cdev->name, brightness);
led->status = !!brightness;
schedule_work(&led->work);
}
static void lp3944_led_work(struct work_struct *work)
{
struct lp3944_led_data *led;
led = container_of(work, struct lp3944_led_data, work);
lp3944_led_set(led, led->status);
}
static int lp3944_configure(struct i2c_client *client,
struct lp3944_data *data,
struct lp3944_platform_data *pdata)
{
int i, err = 0;
for (i = 0; i < pdata->leds_size; i++) {
struct lp3944_led *pled = &pdata->leds[i];
struct lp3944_led_data *led = &data->leds[i];
led->client = client;
led->id = i;
switch (pled->type) {
case LP3944_LED_TYPE_LED:
case LP3944_LED_TYPE_LED_INVERTED:
led->type = pled->type;
led->status = pled->status;
led->ldev.name = pled->name;
led->ldev.max_brightness = 1;
led->ldev.brightness_set = lp3944_led_set_brightness;
led->ldev.blink_set = lp3944_led_set_blink;
led->ldev.flags = LED_CORE_SUSPENDRESUME;
INIT_WORK(&led->work, lp3944_led_work);
err = led_classdev_register(&client->dev, &led->ldev);
if (err < 0) {
dev_err(&client->dev,
"couldn't register LED %s\n",
led->ldev.name);
goto exit;
}
/* to expose the default value to userspace */
led->ldev.brightness = led->status;
/* Set the default led status */
err = lp3944_led_set(led, led->status);
if (err < 0) {
dev_err(&client->dev,
"%s couldn't set STATUS %d\n",
led->ldev.name, led->status);
goto exit;
}
break;
case LP3944_LED_TYPE_NONE:
default:
break;
}
}
return 0;
exit:
if (i > 0)
for (i = i - 1; i >= 0; i--)
switch (pdata->leds[i].type) {
case LP3944_LED_TYPE_LED:
case LP3944_LED_TYPE_LED_INVERTED:
led_classdev_unregister(&data->leds[i].ldev);
cancel_work_sync(&data->leds[i].work);
break;
case LP3944_LED_TYPE_NONE:
default:
break;
}
return err;
}
static int lp3944_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct lp3944_platform_data *lp3944_pdata =
dev_get_platdata(&client->dev);
struct lp3944_data *data;
int err;
if (lp3944_pdata == NULL) {
dev_err(&client->dev, "no platform data\n");
return -EINVAL;
}
/* Let's see whether this adapter can support what we need. */
if (!i2c_check_functionality(client->adapter,
I2C_FUNC_SMBUS_BYTE_DATA)) {
dev_err(&client->dev, "insufficient functionality!\n");
return -ENODEV;
}
data = devm_kzalloc(&client->dev, sizeof(struct lp3944_data),
GFP_KERNEL);
if (!data)
return -ENOMEM;
data->client = client;
i2c_set_clientdata(client, data);
mutex_init(&data->lock);
err = lp3944_configure(client, data, lp3944_pdata);
if (err < 0)
return err;
dev_info(&client->dev, "lp3944 enabled\n");
return 0;
}
static int lp3944_remove(struct i2c_client *client)
{
struct lp3944_platform_data *pdata = dev_get_platdata(&client->dev);
struct lp3944_data *data = i2c_get_clientdata(client);
int i;
for (i = 0; i < pdata->leds_size; i++)
switch (data->leds[i].type) {
case LP3944_LED_TYPE_LED:
case LP3944_LED_TYPE_LED_INVERTED:
led_classdev_unregister(&data->leds[i].ldev);
cancel_work_sync(&data->leds[i].work);
break;
case LP3944_LED_TYPE_NONE:
default:
break;
}
return 0;
}
/* lp3944 i2c driver struct */
static const struct i2c_device_id lp3944_id[] = {
{"lp3944", 0},
{}
};
MODULE_DEVICE_TABLE(i2c, lp3944_id);
static struct i2c_driver lp3944_driver = {
.driver = {
.name = "lp3944",
},
.probe = lp3944_probe,
.remove = lp3944_remove,
.id_table = lp3944_id,
};
module_i2c_driver(lp3944_driver);
MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
MODULE_DESCRIPTION("LP3944 Fun Light Chip");
MODULE_LICENSE("GPL");