--- /dev/null
+/*
+ * 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 =
+ (enum led_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");
Code Review / kvmfornfv.git / blobdiff