/*
 * Driver for PCA9685 16-channel 12-bit PWM LED controller
 *
 * Copyright (C) 2013 Steffen Trumtrar <s.trumtrar@pengutronix.de>
 * Copyright (C) 2015 Clemens Gruber <clemens.gruber@pqgruber.com>
 *
 * based on the pwm-twl-led.c driver
 *
 * 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/acpi.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/pwm.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/delay.h>

/*
 * Because the PCA9685 has only one prescaler per chip, changing the period of
 * one channel affects the period of all 16 PWM outputs!
 * However, the ratio between each configured duty cycle and the chip-wide
 * period remains constant, because the OFF time is set in proportion to the
 * counter range.
 */

#define PCA9685_MODE1           0x00
#define PCA9685_MODE2           0x01
#define PCA9685_SUBADDR1        0x02
#define PCA9685_SUBADDR2        0x03
#define PCA9685_SUBADDR3        0x04
#define PCA9685_ALLCALLADDR     0x05
#define PCA9685_LEDX_ON_L       0x06
#define PCA9685_LEDX_ON_H       0x07
#define PCA9685_LEDX_OFF_L      0x08
#define PCA9685_LEDX_OFF_H      0x09

#define PCA9685_ALL_LED_ON_L    0xFA
#define PCA9685_ALL_LED_ON_H    0xFB
#define PCA9685_ALL_LED_OFF_L   0xFC
#define PCA9685_ALL_LED_OFF_H   0xFD
#define PCA9685_PRESCALE        0xFE

#define PCA9685_PRESCALE_MIN    0x03    /* => max. frequency of 1526 Hz */
#define PCA9685_PRESCALE_MAX    0xFF    /* => min. frequency of 24 Hz */

#define PCA9685_COUNTER_RANGE   4096
#define PCA9685_DEFAULT_PERIOD  5000000 /* Default period_ns = 1/200 Hz */
#define PCA9685_OSC_CLOCK_MHZ   25      /* Internal oscillator with 25 MHz */

#define PCA9685_NUMREGS         0xFF
#define PCA9685_MAXCHAN         0x10

#define LED_FULL                (1 << 4)
#define MODE1_RESTART           (1 << 7)
#define MODE1_SLEEP             (1 << 4)
#define MODE2_INVRT             (1 << 4)
#define MODE2_OUTDRV            (1 << 2)

#define LED_N_ON_H(N)   (PCA9685_LEDX_ON_H + (4 * (N)))
#define LED_N_ON_L(N)   (PCA9685_LEDX_ON_L + (4 * (N)))
#define LED_N_OFF_H(N)  (PCA9685_LEDX_OFF_H + (4 * (N)))
#define LED_N_OFF_L(N)  (PCA9685_LEDX_OFF_L + (4 * (N)))

struct pca9685 {
        struct pwm_chip chip;
        struct regmap *regmap;
        int active_cnt;
        int duty_ns;
        int period_ns;
};

static inline struct pca9685 *to_pca(struct pwm_chip *chip)
{
        return container_of(chip, struct pca9685, chip);
}

static int pca9685_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
                              int duty_ns, int period_ns)
{
        struct pca9685 *pca = to_pca(chip);
        unsigned long long duty;
        unsigned int reg;
        int prescale;

        if (period_ns != pca->period_ns) {
                prescale = DIV_ROUND_CLOSEST(PCA9685_OSC_CLOCK_MHZ * period_ns,
                                             PCA9685_COUNTER_RANGE * 1000) - 1;

                if (prescale >= PCA9685_PRESCALE_MIN &&
                        prescale <= PCA9685_PRESCALE_MAX) {
                        /* Put chip into sleep mode */
                        regmap_update_bits(pca->regmap, PCA9685_MODE1,
                                           MODE1_SLEEP, MODE1_SLEEP);

                        /* Change the chip-wide output frequency */
                        regmap_write(pca->regmap, PCA9685_PRESCALE, prescale);

                        /* Wake the chip up */
                        regmap_update_bits(pca->regmap, PCA9685_MODE1,
                                           MODE1_SLEEP, 0x0);

                        /* Wait 500us for the oscillator to be back up */
                        udelay(500);

                        pca->period_ns = period_ns;

                        /*
                         * If the duty cycle did not change, restart PWM with
                         * the same duty cycle to period ratio and return.
                         */
                        if (duty_ns == pca->duty_ns) {
                                regmap_update_bits(pca->regmap, PCA9685_MODE1,
                                                   MODE1_RESTART, 0x1);
                                return 0;
                        }
                } else {
                        dev_err(chip->dev,
                                "prescaler not set: period out of bounds!\n");
                        return -EINVAL;
                }
        }

        pca->duty_ns = duty_ns;

        if (duty_ns < 1) {
                if (pwm->hwpwm >= PCA9685_MAXCHAN)
                        reg = PCA9685_ALL_LED_OFF_H;
                else
                        reg = LED_N_OFF_H(pwm->hwpwm);

                regmap_write(pca->regmap, reg, LED_FULL);

                return 0;
        }

        if (duty_ns == period_ns) {
                /* Clear both OFF registers */
                if (pwm->hwpwm >= PCA9685_MAXCHAN)
                        reg = PCA9685_ALL_LED_OFF_L;
                else
                        reg = LED_N_OFF_L(pwm->hwpwm);

                regmap_write(pca->regmap, reg, 0x0);

                if (pwm->hwpwm >= PCA9685_MAXCHAN)
                        reg = PCA9685_ALL_LED_OFF_H;
                else
                        reg = LED_N_OFF_H(pwm->hwpwm);

                regmap_write(pca->regmap, reg, 0x0);

                /* Set the full ON bit */
                if (pwm->hwpwm >= PCA9685_MAXCHAN)
                        reg = PCA9685_ALL_LED_ON_H;
                else
                        reg = LED_N_ON_H(pwm->hwpwm);

                regmap_write(pca->regmap, reg, LED_FULL);

                return 0;
        }

        duty = PCA9685_COUNTER_RANGE * (unsigned long long)duty_ns;
        duty = DIV_ROUND_UP_ULL(duty, period_ns);

        if (pwm->hwpwm >= PCA9685_MAXCHAN)
                reg = PCA9685_ALL_LED_OFF_L;
        else
                reg = LED_N_OFF_L(pwm->hwpwm);

        regmap_write(pca->regmap, reg, (int)duty & 0xff);

        if (pwm->hwpwm >= PCA9685_MAXCHAN)
                reg = PCA9685_ALL_LED_OFF_H;
        else
                reg = LED_N_OFF_H(pwm->hwpwm);

        regmap_write(pca->regmap, reg, ((int)duty >> 8) & 0xf);

        /* Clear the full ON bit, otherwise the set OFF time has no effect */
        if (pwm->hwpwm >= PCA9685_MAXCHAN)
                reg = PCA9685_ALL_LED_ON_H;
        else
                reg = LED_N_ON_H(pwm->hwpwm);

        regmap_write(pca->regmap, reg, 0);

        return 0;
}

static int pca9685_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct pca9685 *pca = to_pca(chip);
        unsigned int reg;

        /*
         * The PWM subsystem does not support a pre-delay.
         * So, set the ON-timeout to 0
         */
        if (pwm->hwpwm >= PCA9685_MAXCHAN)
                reg = PCA9685_ALL_LED_ON_L;
        else
                reg = LED_N_ON_L(pwm->hwpwm);

        regmap_write(pca->regmap, reg, 0);

        if (pwm->hwpwm >= PCA9685_MAXCHAN)
                reg = PCA9685_ALL_LED_ON_H;
        else
                reg = LED_N_ON_H(pwm->hwpwm);

        regmap_write(pca->regmap, reg, 0);

        /*
         * Clear the full-off bit.
         * It has precedence over the others and must be off.
         */
        if (pwm->hwpwm >= PCA9685_MAXCHAN)
                reg = PCA9685_ALL_LED_OFF_H;
        else
                reg = LED_N_OFF_H(pwm->hwpwm);

        regmap_update_bits(pca->regmap, reg, LED_FULL, 0x0);

        return 0;
}

static void pca9685_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct pca9685 *pca = to_pca(chip);
        unsigned int reg;

        if (pwm->hwpwm >= PCA9685_MAXCHAN)
                reg = PCA9685_ALL_LED_OFF_H;
        else
                reg = LED_N_OFF_H(pwm->hwpwm);

        regmap_write(pca->regmap, reg, LED_FULL);

        /* Clear the LED_OFF counter. */
        if (pwm->hwpwm >= PCA9685_MAXCHAN)
                reg = PCA9685_ALL_LED_OFF_L;
        else
                reg = LED_N_OFF_L(pwm->hwpwm);

        regmap_write(pca->regmap, reg, 0x0);
}

static int pca9685_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct pca9685 *pca = to_pca(chip);

        if (pca->active_cnt++ == 0)
                return regmap_update_bits(pca->regmap, PCA9685_MODE1,
                                          MODE1_SLEEP, 0x0);

        return 0;
}

static void pca9685_pwm_free(struct pwm_chip *chip, struct pwm_device *pwm)
{
        struct pca9685 *pca = to_pca(chip);

        if (--pca->active_cnt == 0)
                regmap_update_bits(pca->regmap, PCA9685_MODE1, MODE1_SLEEP,
                                   MODE1_SLEEP);
}

static const struct pwm_ops pca9685_pwm_ops = {
        .enable = pca9685_pwm_enable,
        .disable = pca9685_pwm_disable,
        .config = pca9685_pwm_config,
        .request = pca9685_pwm_request,
        .free = pca9685_pwm_free,
        .owner = THIS_MODULE,
};

static const struct regmap_config pca9685_regmap_i2c_config = {
        .reg_bits = 8,
        .val_bits = 8,
        .max_register = PCA9685_NUMREGS,
        .cache_type = REGCACHE_NONE,
};

static int pca9685_pwm_probe(struct i2c_client *client,
                                const struct i2c_device_id *id)
{
        struct pca9685 *pca;
        int ret;
        int mode2;

        pca = devm_kzalloc(&client->dev, sizeof(*pca), GFP_KERNEL);
        if (!pca)
                return -ENOMEM;

        pca->regmap = devm_regmap_init_i2c(client, &pca9685_regmap_i2c_config);
        if (IS_ERR(pca->regmap)) {
                ret = PTR_ERR(pca->regmap);
                dev_err(&client->dev, "Failed to initialize register map: %d\n",
                        ret);
                return ret;
        }
        pca->duty_ns = 0;
        pca->period_ns = PCA9685_DEFAULT_PERIOD;

        i2c_set_clientdata(client, pca);

        regmap_read(pca->regmap, PCA9685_MODE2, &mode2);

        if (device_property_read_bool(&client->dev, "invert"))
                mode2 |= MODE2_INVRT;
        else
                mode2 &= ~MODE2_INVRT;

        if (device_property_read_bool(&client->dev, "open-drain"))
                mode2 &= ~MODE2_OUTDRV;
        else
                mode2 |= MODE2_OUTDRV;

        regmap_write(pca->regmap, PCA9685_MODE2, mode2);

        /* clear all "full off" bits */
        regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, 0);
        regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, 0);

        pca->chip.ops = &pca9685_pwm_ops;
        /* add an extra channel for ALL_LED */
        pca->chip.npwm = PCA9685_MAXCHAN + 1;

        pca->chip.dev = &client->dev;
        pca->chip.base = -1;
        pca->chip.can_sleep = true;

        return pwmchip_add(&pca->chip);
}

static int pca9685_pwm_remove(struct i2c_client *client)
{
        struct pca9685 *pca = i2c_get_clientdata(client);

        regmap_update_bits(pca->regmap, PCA9685_MODE1, MODE1_SLEEP,
                           MODE1_SLEEP);

        return pwmchip_remove(&pca->chip);
}

static const struct i2c_device_id pca9685_id[] = {
        { "pca9685", 0 },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(i2c, pca9685_id);

#ifdef CONFIG_ACPI
static const struct acpi_device_id pca9685_acpi_ids[] = {
        { "INT3492", 0 },
        { /* sentinel */ },
};
MODULE_DEVICE_TABLE(acpi, pca9685_acpi_ids);
#endif

#ifdef CONFIG_OF
static const struct of_device_id pca9685_dt_ids[] = {
        { .compatible = "nxp,pca9685-pwm", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, pca9685_dt_ids);
#endif

static struct i2c_driver pca9685_i2c_driver = {
        .driver = {
                .name = "pca9685-pwm",
                .acpi_match_table = ACPI_PTR(pca9685_acpi_ids),
                .of_match_table = of_match_ptr(pca9685_dt_ids),
        },
        .probe = pca9685_pwm_probe,
        .remove = pca9685_pwm_remove,
        .id_table = pca9685_id,
};

module_i2c_driver(pca9685_i2c_driver);

MODULE_AUTHOR("Steffen Trumtrar <s.trumtrar@pengutronix.de>");
MODULE_DESCRIPTION("PWM driver for PCA9685");
MODULE_LICENSE("GPL");