linux-imx

/*

 * Driver for TWL4030/6030 Pulse Width Modulator used as LED driver

 *

 * Copyright (C) 2012 Texas Instruments

 * Author: Peter Ujfalusi <peter.ujfalusi@ti.com>

 *

 * This driver is a complete rewrite of the former pwm-twl6030.c authorded by:

 * Hemanth V <hemanthv@ti.com>

 *

 * 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.

 *

 * This program is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for

 * more details.

 *

 * You should have received a copy of the GNU General Public License along with

 * this program.  If not, see <http://www.gnu.org/licenses/>.

 */

​

#include <linux/module.h>

#include <linux/of.h>

#include <linux/platform_device.h>

#include <linux/pwm.h>

#include <linux/mfd/twl.h>

#include <linux/slab.h>

​

/*

 * This driver handles the PWM driven LED terminals of TWL4030 and TWL6030.

 * To generate the signal on TWL4030:

 *  - LEDA uses PWMA

 *  - LEDB uses PWMB

 * TWL6030 has one LED pin with dedicated LEDPWM

 */

​

#define TWL4030_LED_MAX     0x7f

#define TWL6030_LED_MAX     0xff

​

/* Registers, bits and macro for TWL4030 */

#define TWL4030_LEDEN_REG   0x00

#define TWL4030_PWMA_REG    0x01

​

#define TWL4030_LEDXON      (1 << 0)

#define TWL4030_LEDXPWM     (1 << 4)

#define TWL4030_LED_PINS    (TWL4030_LEDXON | TWL4030_LEDXPWM)

#define TWL4030_LED_TOGGLE(led, x)  ((x) << (led))

​

/* Register, bits and macro for TWL6030 */

#define TWL6030_LED_PWM_CTRL1   0xf4

#define TWL6030_LED_PWM_CTRL2   0xf5

​

#define TWL6040_LED_MODE_HW 0x00

#define TWL6040_LED_MODE_ON 0x01

#define TWL6040_LED_MODE_OFF    0x02

#define TWL6040_LED_MODE_MASK   0x03

​

struct twl_pwmled_chip {

    struct pwm_chip chip;

    struct mutex mutex;

};

​

static inline struct twl_pwmled_chip *to_twl(struct pwm_chip *chip)

{

    return container_of(chip, struct twl_pwmled_chip, chip);

}

​

static int twl4030_pwmled_config(struct pwm_chip *chip, struct pwm_device *pwm,

                  int duty_ns, int period_ns)

{

    int duty_cycle = DIV_ROUND_UP(duty_ns * TWL4030_LED_MAX, period_ns) + 1;

    u8 pwm_config[2] = { 1, 0 };

    int base, ret;

​

    /*

     * To configure the duty period:

     * On-cycle is set to 1 (the minimum allowed value)

     * The off time of 0 is not configurable, so the mapping is:

     * 0 -> off cycle = 2,

     * 1 -> off cycle = 2,

     * 2 -> off cycle = 3,

     * 126 - > off cycle 127,

     * 127 - > off cycle 1

     * When on cycle == off cycle the PWM will be always on

     */

    if (duty_cycle == 1)

        duty_cycle = 2;

    else if (duty_cycle > TWL4030_LED_MAX)

        duty_cycle = 1;

​

    base = pwm->hwpwm * 2 + TWL4030_PWMA_REG;