// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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
 */

#include <linux/gpio/driver.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/mutex.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>
#include <linux/pm_runtime.h>
#include <linux/bitmap.h>

/*
 * Because the PCA9685 has only one prescaler per chip, only the first channel
 * that is enabled is allowed to change the prescale register.
 * PWM channels requested afterwards must use a period that results in the same
 * prescale setting as the one set by the first requested channel.
 */

#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_OSC_CLOCK_HZ    25000000        /* Internal oscillator with 25 MHz */

/*
 * The time value of one counter tick. Note that NSEC_PER_SEC is an integer
 * multiple of PCA9685_OSC_CLOCK_HZ, so there is no rounding involved and we're
 * not loosing precision due to the early division.
 */
#define PCA9685_QUANTUM_NS(_prescale)   ((NSEC_PER_SEC / PCA9685_OSC_CLOCK_HZ) * (_prescale + 1))

#define PCA9685_NUMREGS         0xFF
#define PCA9685_MAXCHAN         0x10

#define LED_FULL                BIT(4)
#define MODE1_ALLCALL           BIT(0)
#define MODE1_SUB3              BIT(1)
#define MODE1_SUB2              BIT(2)
#define MODE1_SUB1              BIT(3)
#define MODE1_SLEEP             BIT(4)
#define MODE1_AI                BIT(5)

#define MODE2_INVRT             BIT(4)
#define MODE2_OUTDRV            BIT(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)))

#define REG_ON_H(C)     ((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_ON_H : LED_N_ON_H((C)))
#define REG_ON_L(C)     ((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_ON_L : LED_N_ON_L((C)))
#define REG_OFF_H(C)    ((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_OFF_H : LED_N_OFF_H((C)))
#define REG_OFF_L(C)    ((C) >= PCA9685_MAXCHAN ? PCA9685_ALL_LED_OFF_L : LED_N_OFF_L((C)))

struct pca9685 {
        struct regmap *regmap;
        struct mutex lock;
        DECLARE_BITMAP(pwms_enabled, PCA9685_MAXCHAN + 1);
};

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

/* This function is supposed to be called with the lock mutex held */
static bool pca9685_prescaler_can_change(struct pca9685 *pca, int channel)
{
        /* No PWM enabled: Change allowed */
        if (bitmap_empty(pca->pwms_enabled, PCA9685_MAXCHAN + 1))
                return true;
        /* More than one PWM enabled: Change not allowed */
        if (bitmap_weight(pca->pwms_enabled, PCA9685_MAXCHAN + 1) > 1)
                return false;
        /*
         * Only one PWM enabled: Change allowed if the PWM about to
         * be changed is the one that is already enabled
         */
        return test_bit(channel, pca->pwms_enabled);
}

static int pca9685_read_reg(struct pwm_chip *chip, unsigned int reg, unsigned int *val)
{
        struct pca9685 *pca = to_pca(chip);
        struct device *dev = pwmchip_parent(chip);
        int err;

        err = regmap_read(pca->regmap, reg, val);
        if (err)
                dev_err(dev, "regmap_read of register 0x%x failed: %pe\n", reg, ERR_PTR(err));

        return err;
}

static int pca9685_write_reg(struct pwm_chip *chip, unsigned int reg, unsigned int val)
{
        struct pca9685 *pca = to_pca(chip);
        struct device *dev = pwmchip_parent(chip);
        int err;

        err = regmap_write(pca->regmap, reg, val);
        if (err)
                dev_err(dev, "regmap_write to register 0x%x failed: %pe\n", reg, ERR_PTR(err));

        return err;
}

static int pca9685_write_4reg(struct pwm_chip *chip, unsigned int reg, u8 val[4])
{
        struct pca9685 *pca = to_pca(chip);
        struct device *dev = pwmchip_parent(chip);
        int err;

        err = regmap_bulk_write(pca->regmap, reg, val, 4);
        if (err)
                dev_err(dev, "regmap_write to register 0x%x failed: %pe\n", reg, ERR_PTR(err));

        return err;
}

static int pca9685_set_sleep_mode(struct pwm_chip *chip, bool enable)
{
        struct pca9685 *pca = to_pca(chip);
        int err;

        err = regmap_update_bits(pca->regmap, PCA9685_MODE1,
                                 MODE1_SLEEP, enable ? MODE1_SLEEP : 0);
        if (err)
                return err;

        if (!enable) {
                /* Wait 500us for the oscillator to be back up */
                udelay(500);
        }

        return 0;
}

struct pca9685_waveform {
        u8 onoff[4];
        u8 prescale;
};

static int pca9685_round_waveform_tohw(struct pwm_chip *chip, struct pwm_device *pwm, const struct pwm_waveform *wf, void *_wfhw)
{
        struct pca9685_waveform *wfhw = _wfhw;
        struct pca9685 *pca = to_pca(chip);
        unsigned int best_prescale;
        u8 prescale;
        unsigned int period_ns, duty;
        int ret_tohw = 0;

        if (!wf->period_length_ns) {
                *wfhw = (typeof(*wfhw)){
                        .onoff = { 0, 0, 0, LED_FULL, },
                        .prescale = 0,
                };

                dev_dbg(&chip->dev, "pwm#%u: %lld/%lld [+%lld] -> [%hhx %hhx %hhx %hhx] PSC:%hhx\n",
                        pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
                        wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale);

                return 0;
        }

        if (wf->period_length_ns >= PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(255)) {
                best_prescale = 255;
        } else if (wf->period_length_ns < PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(3)) {
                best_prescale = 3;
                ret_tohw = 1;
        } else {
                best_prescale = (unsigned int)wf->period_length_ns / (PCA9685_COUNTER_RANGE * (NSEC_PER_SEC / PCA9685_OSC_CLOCK_HZ)) - 1;
        }

        guard(mutex)(&pca->lock);

        if (!pca9685_prescaler_can_change(pca, pwm->hwpwm)) {
                unsigned int current_prescale;
                int ret;

                ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &current_prescale);
                if (ret)
                        return ret;

                if (current_prescale > best_prescale)
                        ret_tohw = 1;

                prescale = current_prescale;
        } else {
                prescale = best_prescale;
        }

        period_ns = PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);

        duty = (unsigned)min_t(u64, wf->duty_length_ns, period_ns) / PCA9685_QUANTUM_NS(prescale);

        if (duty < PCA9685_COUNTER_RANGE) {
                unsigned int on, off;

                on = (unsigned)min_t(u64, wf->duty_offset_ns, period_ns) / PCA9685_QUANTUM_NS(prescale);
                off = (on + duty) % PCA9685_COUNTER_RANGE;

                /*
                 * With a zero duty cycle, it doesn't matter if period was
                 * rounded up
                 */
                if (!duty)
                        ret_tohw = 0;

                *wfhw = (typeof(*wfhw)){
                        .onoff = { on & 0xff, (on >> 8) & 0xf, off & 0xff, (off >> 8) & 0xf },
                        .prescale = prescale,
                };
        } else {
                *wfhw = (typeof(*wfhw)){
                        .onoff = { 0, LED_FULL, 0, 0, },
                        .prescale = prescale,
                };
        }

        dev_dbg(&chip->dev, "pwm#%u: %lld/%lld [+%lld] -> %s[%hhx %hhx %hhx %hhx] PSC:%hhx\n",
                pwm->hwpwm, wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns,
                ret_tohw ? "#" : "", wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale);

        return ret_tohw;
}

static int pca9685_round_waveform_fromhw(struct pwm_chip *chip, struct pwm_device *pwm,
                                         const void *_wfhw, struct pwm_waveform *wf)
{
        const struct pca9685_waveform *wfhw = _wfhw;
        struct pca9685 *pca = to_pca(chip);
        unsigned int prescale;

        if (wfhw->prescale)
                prescale = wfhw->prescale;
        else
                scoped_guard(mutex, &pca->lock) {
                        int ret;

                        ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &prescale);
                        if (ret)
                                return ret;
                }

        wf->period_length_ns = PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);

        if (wfhw->onoff[3] & LED_FULL) {
                wf->duty_length_ns = 0;
                wf->duty_offset_ns = 0;
        } else if (wfhw->onoff[1] & LED_FULL) {
                wf->duty_length_ns = wf->period_length_ns;
                wf->duty_offset_ns = 0;
        } else {
                unsigned int on = wfhw->onoff[0] | (wfhw->onoff[1] & 0xf) << 8;
                unsigned int off = wfhw->onoff[2] | (wfhw->onoff[3] & 0xf) << 8;

                wf->duty_length_ns = (off - on) % PCA9685_COUNTER_RANGE * PCA9685_QUANTUM_NS(prescale);
                wf->duty_offset_ns = on * PCA9685_QUANTUM_NS(prescale);
        }

        dev_dbg(&chip->dev, "pwm#%u: [%hhx %hhx %hhx %hhx] PSC:%hhx -> %lld/%lld [+%lld]\n",
                pwm->hwpwm,
                wfhw->onoff[0], wfhw->onoff[1], wfhw->onoff[2], wfhw->onoff[3], wfhw->prescale,
                wf->duty_length_ns, wf->period_length_ns, wf->duty_offset_ns);

        return 0;
}

static int pca9685_read_waveform(struct pwm_chip *chip, struct pwm_device *pwm, void *_wfhw)
{
        struct pca9685_waveform *wfhw = _wfhw;
        struct pca9685 *pca = to_pca(chip);
        unsigned int prescale;
        int ret;

        guard(mutex)(&pca->lock);

        ret = regmap_bulk_read(pca->regmap, REG_ON_L(pwm->hwpwm), &wfhw->onoff, 4);
        if (ret)
                return ret;

        ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &prescale);
        if (ret)
                return ret;

        wfhw->prescale = prescale;

        return 0;
}

static int pca9685_write_waveform(struct pwm_chip *chip, struct pwm_device *pwm, const void *_wfhw)
{
        const struct pca9685_waveform *wfhw = _wfhw;
        struct pca9685 *pca = to_pca(chip);
        unsigned int current_prescale;
        int ret;

        guard(mutex)(&pca->lock);

        if (wfhw->prescale) {
                ret = regmap_read(pca->regmap, PCA9685_PRESCALE, &current_prescale);
                if (ret)
                        return ret;

                if (current_prescale != wfhw->prescale) {
                        if (!pca9685_prescaler_can_change(pca, pwm->hwpwm))
                                return -EBUSY;

                        /* Put chip into sleep mode */
                        ret = pca9685_set_sleep_mode(chip, true);
                        if (ret)
                                return ret;

                        /* Change the chip-wide output frequency */
                        ret = regmap_write(pca->regmap, PCA9685_PRESCALE, wfhw->prescale);
                        if (ret)
                                return ret;

                        /* Wake the chip up */
                        ret = pca9685_set_sleep_mode(chip, false);
                        if (ret)
                                return ret;
                }
        }

        return regmap_bulk_write(pca->regmap, REG_ON_L(pwm->hwpwm), &wfhw->onoff, 4);
}

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

        if (pwm->hwpwm < PCA9685_MAXCHAN) {
                /* PWMs - except the "all LEDs" channel - default to enabled */
                mutex_lock(&pca->lock);
                set_bit(pwm->hwpwm, pca->pwms_enabled);
                mutex_unlock(&pca->lock);
        }

        pm_runtime_get_sync(pwmchip_parent(chip));

        return 0;
}

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

        mutex_lock(&pca->lock);
        clear_bit(pwm->hwpwm, pca->pwms_enabled);
        mutex_unlock(&pca->lock);

        pm_runtime_put(pwmchip_parent(chip));
}

static const struct pwm_ops pca9685_pwm_ops = {
        .sizeof_wfhw = sizeof(struct pca9685_waveform),
        .round_waveform_tohw = pca9685_round_waveform_tohw,
        .round_waveform_fromhw = pca9685_round_waveform_fromhw,
        .read_waveform = pca9685_read_waveform,
        .write_waveform = pca9685_write_waveform,
        .request = pca9685_pwm_request,
        .free = pca9685_pwm_free,
};

static bool pca9685_readable_reg(struct device *dev, unsigned int reg)
{
        /* The ALL_LED registers are readable but read as zero */
        return reg <= REG_OFF_H(15) || reg >= PCA9685_PRESCALE;
}

static bool pca9685_writeable_reg(struct device *dev, unsigned int reg)
{
        return reg <= REG_OFF_H(15) || reg >= PCA9685_ALL_LED_ON_L;
}

static bool pca9685_volatile_reg(struct device *dev, unsigned int reg)
{
        /*
         * Writing to an ALL_LED register affects all LEDi registers, so they
         * are not cachable. :-\
         */
        return reg < PCA9685_PRESCALE;
}

static const struct regmap_config pca9685_regmap_i2c_config = {
        .reg_bits = 8,
        .val_bits = 8,

        .readable_reg = pca9685_readable_reg,
        .writeable_reg = pca9685_writeable_reg,
        .volatile_reg = pca9685_volatile_reg,

        .max_register = PCA9685_NUMREGS,
        .cache_type = REGCACHE_MAPLE,
};

static int pca9685_pwm_probe(struct i2c_client *client)
{
        struct pwm_chip *chip;
        struct pca9685 *pca;
        unsigned int reg;
        int ret;

        /* Add an extra channel for ALL_LED */
        chip = devm_pwmchip_alloc(&client->dev, PCA9685_MAXCHAN + 1, sizeof(*pca));
        if (IS_ERR(chip))
                return PTR_ERR(chip);
        pca = to_pca(chip);

        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;
        }

        i2c_set_clientdata(client, chip);

        mutex_init(&pca->lock);

        /* clear MODE2_OCH */
        reg = 0;

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

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

        ret = pca9685_write_reg(chip, PCA9685_MODE2, reg);
        if (ret)
                return ret;

        /*
         * Disable all LED ALLCALL and SUBx addresses to avoid bus collisions,
         * enable Auto-Increment.
         */
        pca9685_read_reg(chip, PCA9685_MODE1, &reg);
        reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
        reg |= MODE1_AI;
        pca9685_write_reg(chip, PCA9685_MODE1, reg);

        /* Reset OFF/ON registers to POR default */
        ret = pca9685_write_4reg(chip, PCA9685_ALL_LED_ON_L, (u8[]){ 0, LED_FULL, 0, LED_FULL });
        if (ret < 0)
                return dev_err_probe(&client->dev, ret, "Failed to reset ON/OFF registers\n");

        chip->ops = &pca9685_pwm_ops;

        ret = pwmchip_add(chip);
        if (ret < 0)
                return ret;

        pm_runtime_enable(&client->dev);

        if (pm_runtime_enabled(&client->dev)) {
                /*
                 * Although the chip comes out of power-up in the sleep state,
                 * we force it to sleep in case it was woken up before
                 */
                pca9685_set_sleep_mode(chip, true);
                pm_runtime_set_suspended(&client->dev);
        } else {
                /* Wake the chip up if runtime PM is disabled */
                pca9685_set_sleep_mode(chip, false);
        }

        return 0;
}

static void pca9685_pwm_remove(struct i2c_client *client)
{
        struct pwm_chip *chip = i2c_get_clientdata(client);

        pwmchip_remove(chip);

        if (!pm_runtime_enabled(&client->dev)) {
                /* Put chip in sleep state if runtime PM is disabled */
                pca9685_set_sleep_mode(chip, true);
        }

        pm_runtime_disable(&client->dev);
}

static int __maybe_unused pca9685_pwm_runtime_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct pwm_chip *chip = i2c_get_clientdata(client);

        pca9685_set_sleep_mode(chip, true);
        return 0;
}

static int __maybe_unused pca9685_pwm_runtime_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct pwm_chip *chip = i2c_get_clientdata(client);

        pca9685_set_sleep_mode(chip, false);
        return 0;
}

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

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

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

static const struct dev_pm_ops pca9685_pwm_pm = {
        SET_RUNTIME_PM_OPS(pca9685_pwm_runtime_suspend,
                           pca9685_pwm_runtime_resume, NULL)
};

static struct i2c_driver pca9685_i2c_driver = {
        .driver = {
                .name = "pca9685-pwm",
                .acpi_match_table = pca9685_acpi_ids,
                .of_match_table = pca9685_dt_ids,
                .pm = &pca9685_pwm_pm,
        },
        .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");