leds: LED driver for National Semiconductor LP3944 Funlight Chip

LEDs 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.

Signed-off-by: Antonio Ospite <ospite@studenti.unina.it>
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>

1 files changed, 466 insertions, 0 deletions

diff --git a/drivers/leds/leds-lp3944.c b/drivers/leds/leds-lp3944.c
new file mode 100644
index 000000000000..5946208ba26e
--- /dev/null
+++ b/drivers/leds/leds-lp3944.c
@@ -0,0 +1,466 @@
+/*
+ * 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/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 -EINVAL;
+
+        *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 __devinit lp3944_probe(struct i2c_client *client,
+                                  const struct i2c_device_id *id)
+{
+        struct lp3944_platform_data *lp3944_pdata = client->dev.platform_data;
+        struct lp3944_data *data;
+
+        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 = kzalloc(sizeof(struct lp3944_data), GFP_KERNEL);
+        if (!data)
+                return -ENOMEM;
+
+        data->client = client;
+        i2c_set_clientdata(client, data);
+
+        mutex_init(&data->lock);
+
+        dev_info(&client->dev, "lp3944 enabled\n");
+
+        lp3944_configure(client, data, lp3944_pdata);
+        return 0;
+}
+
+static int __devexit lp3944_remove(struct i2c_client *client)
+{
+        struct lp3944_platform_data *pdata = client->dev.platform_data;
+        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;
+                }
+
+        kfree(data);
+        i2c_set_clientdata(client, NULL);
+
+        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   = __devexit_p(lp3944_remove),
+        .id_table = lp3944_id,
+};
+
+static int __init lp3944_module_init(void)
+{
+        return i2c_add_driver(&lp3944_driver);
+}
+
+static void __exit lp3944_module_exit(void)
+{
+        i2c_del_driver(&lp3944_driver);
+}
+
+module_init(lp3944_module_init);
+module_exit(lp3944_module_exit);
+
+MODULE_AUTHOR("Antonio Ospite <ospite@studenti.unina.it>");
+MODULE_DESCRIPTION("LP3944 Fun Light Chip");
+MODULE_LICENSE("GPL");