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Release 4.10 drivers/leds/leds-lp3944.c

Directory: drivers/leds
/*
 * 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/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;
	
struct led_classdev ldev;
	
struct i2c_client *client;
};


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; }

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static int lp3944_reg_write(struct i2c_client *client, u8 reg, u8 value) { return i2c_smbus_write_byte_data(client, reg, value); }

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/** * 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; }

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/** * 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; }

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/** * 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 status only when it's < 2 (i.e. 0 or 1) which means it's * controlling the on/off state directly. * When, instead, status is >= 2 don't invert it because it would mean * to mess with the hardware blinking mode. */ 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; }

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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__); lp3944_led_set(led, LP3944_LED_STATUS_DIM0); return 0; }

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static int 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); return lp3944_led_set(led, !!brightness); }

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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->ldev.name = pled->name; led->ldev.max_brightness = 1; led->ldev.brightness_set_blocking = lp3944_led_set_brightness; led->ldev.blink_set = lp3944_led_set_blink; led->ldev.flags = LED_CORE_SUSPENDRESUME; 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 = (enum led_brightness) pled->status; /* Set the default led status */ err = lp3944_led_set(led, pled->status); if (err < 0) { dev_err(&client->dev, "%s couldn't set STATUS %d\n", led->ldev.name, pled->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); break; case LP3944_LED_TYPE_NONE: default: break; } return err; }

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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; }

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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); break; case LP3944_LED_TYPE_NONE: default: break; } return 0; }

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/* 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");

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Directory: drivers/leds
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