// 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/acpi.h>
#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.
 * GPIOs do not count as enabled PWMs as they are not using the prescaler.
 */

#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_MHZ   25      /* Internal oscillator with 25 MHz */

#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 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 pwm_chip chip;
        struct regmap *regmap;
        struct mutex lock;
        DECLARE_BITMAP(pwms_enabled, PCA9685_MAXCHAN + 1);
#if IS_ENABLED(CONFIG_GPIOLIB)
        struct gpio_chip gpio;
        DECLARE_BITMAP(pwms_inuse, PCA9685_MAXCHAN + 1);
#endif
};

static inline struct pca9685 *to_pca(struct pwm_chip *chip)
{
        return container_of(chip, struct pca9685, 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 pca9685 *pca, unsigned int reg, unsigned int *val)
{
        struct device *dev = pca->chip.dev;
        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 pca9685 *pca, unsigned int reg, unsigned int val)
{
        struct device *dev = pca->chip.dev;
        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;
}

/* Helper function to set the duty cycle ratio to duty/4096 (e.g. duty=2048 -> 50%) */
static void pca9685_pwm_set_duty(struct pca9685 *pca, int channel, unsigned int duty)
{
        struct pwm_device *pwm = &pca->chip.pwms[channel];
        unsigned int on, off;

        if (duty == 0) {
                /* Set the full OFF bit, which has the highest precedence */
                pca9685_write_reg(pca, REG_OFF_H(channel), LED_FULL);
                return;
        } else if (duty >= PCA9685_COUNTER_RANGE) {
                /* Set the full ON bit and clear the full OFF bit */
                pca9685_write_reg(pca, REG_ON_H(channel), LED_FULL);
                pca9685_write_reg(pca, REG_OFF_H(channel), 0);
                return;
        }


        if (pwm->state.usage_power && channel < PCA9685_MAXCHAN) {
                /*
                 * If usage_power is set, the pca9685 driver will phase shift
                 * the individual channels relative to their channel number.
                 * This improves EMI because the enabled channels no longer
                 * turn on at the same time, while still maintaining the
                 * configured duty cycle / power output.
                 */
                on = channel * PCA9685_COUNTER_RANGE / PCA9685_MAXCHAN;
        } else
                on = 0;

        off = (on + duty) % PCA9685_COUNTER_RANGE;

        /* Set ON time (clears full ON bit) */
        pca9685_write_reg(pca, REG_ON_L(channel), on & 0xff);
        pca9685_write_reg(pca, REG_ON_H(channel), (on >> 8) & 0xf);
        /* Set OFF time (clears full OFF bit) */
        pca9685_write_reg(pca, REG_OFF_L(channel), off & 0xff);
        pca9685_write_reg(pca, REG_OFF_H(channel), (off >> 8) & 0xf);
}

static unsigned int pca9685_pwm_get_duty(struct pca9685 *pca, int channel)
{
        struct pwm_device *pwm = &pca->chip.pwms[channel];
        unsigned int off = 0, on = 0, val = 0;

        if (WARN_ON(channel >= PCA9685_MAXCHAN)) {
                /* HW does not support reading state of "all LEDs" channel */
                return 0;
        }

        pca9685_read_reg(pca, LED_N_OFF_H(channel), &off);
        if (off & LED_FULL) {
                /* Full OFF bit is set */
                return 0;
        }

        pca9685_read_reg(pca, LED_N_ON_H(channel), &on);
        if (on & LED_FULL) {
                /* Full ON bit is set */
                return PCA9685_COUNTER_RANGE;
        }

        pca9685_read_reg(pca, LED_N_OFF_L(channel), &val);
        off = ((off & 0xf) << 8) | (val & 0xff);
        if (!pwm->state.usage_power)
                return off;

        /* Read ON register to calculate duty cycle of staggered output */
        if (pca9685_read_reg(pca, LED_N_ON_L(channel), &val)) {
                /* Reset val to 0 in case reading LED_N_ON_L failed */
                val = 0;
        }
        on = ((on & 0xf) << 8) | (val & 0xff);
        return (off - on) & (PCA9685_COUNTER_RANGE - 1);
}

#if IS_ENABLED(CONFIG_GPIOLIB)
static bool pca9685_pwm_test_and_set_inuse(struct pca9685 *pca, int pwm_idx)
{
        bool is_inuse;

        mutex_lock(&pca->lock);
        if (pwm_idx >= PCA9685_MAXCHAN) {
                /*
                 * "All LEDs" channel:
                 * pretend already in use if any of the PWMs are requested
                 */
                if (!bitmap_empty(pca->pwms_inuse, PCA9685_MAXCHAN)) {
                        is_inuse = true;
                        goto out;
                }
        } else {
                /*
                 * Regular channel:
                 * pretend already in use if the "all LEDs" channel is requested
                 */
                if (test_bit(PCA9685_MAXCHAN, pca->pwms_inuse)) {
                        is_inuse = true;
                        goto out;
                }
        }
        is_inuse = test_and_set_bit(pwm_idx, pca->pwms_inuse);
out:
        mutex_unlock(&pca->lock);
        return is_inuse;
}

static void pca9685_pwm_clear_inuse(struct pca9685 *pca, int pwm_idx)
{
        mutex_lock(&pca->lock);
        clear_bit(pwm_idx, pca->pwms_inuse);
        mutex_unlock(&pca->lock);
}

static int pca9685_pwm_gpio_request(struct gpio_chip *gpio, unsigned int offset)
{
        struct pca9685 *pca = gpiochip_get_data(gpio);

        if (pca9685_pwm_test_and_set_inuse(pca, offset))
                return -EBUSY;
        pm_runtime_get_sync(pca->chip.dev);
        return 0;
}

static int pca9685_pwm_gpio_get(struct gpio_chip *gpio, unsigned int offset)
{
        struct pca9685 *pca = gpiochip_get_data(gpio);

        return pca9685_pwm_get_duty(pca, offset) != 0;
}

static void pca9685_pwm_gpio_set(struct gpio_chip *gpio, unsigned int offset,
                                 int value)
{
        struct pca9685 *pca = gpiochip_get_data(gpio);

        pca9685_pwm_set_duty(pca, offset, value ? PCA9685_COUNTER_RANGE : 0);
}

static void pca9685_pwm_gpio_free(struct gpio_chip *gpio, unsigned int offset)
{
        struct pca9685 *pca = gpiochip_get_data(gpio);

        pca9685_pwm_set_duty(pca, offset, 0);
        pm_runtime_put(pca->chip.dev);
        pca9685_pwm_clear_inuse(pca, offset);
}

static int pca9685_pwm_gpio_get_direction(struct gpio_chip *chip,
                                          unsigned int offset)
{
        /* Always out */
        return GPIO_LINE_DIRECTION_OUT;
}

static int pca9685_pwm_gpio_direction_input(struct gpio_chip *gpio,
                                            unsigned int offset)
{
        return -EINVAL;
}

static int pca9685_pwm_gpio_direction_output(struct gpio_chip *gpio,
                                             unsigned int offset, int value)
{
        pca9685_pwm_gpio_set(gpio, offset, value);

        return 0;
}

/*
 * The PCA9685 has a bit for turning the PWM output full off or on. Some
 * boards like Intel Galileo actually uses these as normal GPIOs so we
 * expose a GPIO chip here which can exclusively take over the underlying
 * PWM channel.
 */
static int pca9685_pwm_gpio_probe(struct pca9685 *pca)
{
        struct device *dev = pca->chip.dev;

        pca->gpio.label = dev_name(dev);
        pca->gpio.parent = dev;
        pca->gpio.request = pca9685_pwm_gpio_request;
        pca->gpio.free = pca9685_pwm_gpio_free;
        pca->gpio.get_direction = pca9685_pwm_gpio_get_direction;
        pca->gpio.direction_input = pca9685_pwm_gpio_direction_input;
        pca->gpio.direction_output = pca9685_pwm_gpio_direction_output;
        pca->gpio.get = pca9685_pwm_gpio_get;
        pca->gpio.set = pca9685_pwm_gpio_set;
        pca->gpio.base = -1;
        pca->gpio.ngpio = PCA9685_MAXCHAN;
        pca->gpio.can_sleep = true;

        return devm_gpiochip_add_data(dev, &pca->gpio, pca);
}
#else
static inline bool pca9685_pwm_test_and_set_inuse(struct pca9685 *pca,
                                                  int pwm_idx)
{
        return false;
}

static inline void
pca9685_pwm_clear_inuse(struct pca9685 *pca, int pwm_idx)
{
}

static inline int pca9685_pwm_gpio_probe(struct pca9685 *pca)
{
        return 0;
}
#endif

static void pca9685_set_sleep_mode(struct pca9685 *pca, bool enable)
{
        struct device *dev = pca->chip.dev;
        int err = regmap_update_bits(pca->regmap, PCA9685_MODE1,
                                     MODE1_SLEEP, enable ? MODE1_SLEEP : 0);
        if (err) {
                dev_err(dev, "regmap_update_bits of register 0x%x failed: %pe\n",
                        PCA9685_MODE1, ERR_PTR(err));
                return;
        }

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

static int __pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
                               const struct pwm_state *state)
{
        struct pca9685 *pca = to_pca(chip);
        unsigned long long duty, prescale;
        unsigned int val = 0;

        if (state->polarity != PWM_POLARITY_NORMAL)
                return -EINVAL;

        prescale = DIV_ROUND_CLOSEST_ULL(PCA9685_OSC_CLOCK_MHZ * state->period,
                                         PCA9685_COUNTER_RANGE * 1000) - 1;
        if (prescale < PCA9685_PRESCALE_MIN || prescale > PCA9685_PRESCALE_MAX) {
                dev_err(chip->dev, "pwm not changed: period out of bounds!\n");
                return -EINVAL;
        }

        if (!state->enabled) {
                pca9685_pwm_set_duty(pca, pwm->hwpwm, 0);
                return 0;
        }

        pca9685_read_reg(pca, PCA9685_PRESCALE, &val);
        if (prescale != val) {
                if (!pca9685_prescaler_can_change(pca, pwm->hwpwm)) {
                        dev_err(chip->dev,
                                "pwm not changed: periods of enabled pwms must match!\n");
                        return -EBUSY;
                }

                /*
                 * Putting the chip briefly into SLEEP mode
                 * at this point won't interfere with the
                 * pm_runtime framework, because the pm_runtime
                 * state is guaranteed active here.
                 */
                /* Put chip into sleep mode */
                pca9685_set_sleep_mode(pca, true);

                /* Change the chip-wide output frequency */
                pca9685_write_reg(pca, PCA9685_PRESCALE, prescale);

                /* Wake the chip up */
                pca9685_set_sleep_mode(pca, false);
        }

        duty = PCA9685_COUNTER_RANGE * state->duty_cycle;
        duty = DIV_ROUND_UP_ULL(duty, state->period);
        pca9685_pwm_set_duty(pca, pwm->hwpwm, duty);
        return 0;
}

static int pca9685_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
                             const struct pwm_state *state)
{
        struct pca9685 *pca = to_pca(chip);
        int ret;

        mutex_lock(&pca->lock);
        ret = __pca9685_pwm_apply(chip, pwm, state);
        if (ret == 0) {
                if (state->enabled)
                        set_bit(pwm->hwpwm, pca->pwms_enabled);
                else
                        clear_bit(pwm->hwpwm, pca->pwms_enabled);
        }
        mutex_unlock(&pca->lock);

        return ret;
}

static void pca9685_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
                                  struct pwm_state *state)
{
        struct pca9685 *pca = to_pca(chip);
        unsigned long long duty;
        unsigned int val = 0;

        /* Calculate (chip-wide) period from prescale value */
        pca9685_read_reg(pca, PCA9685_PRESCALE, &val);
        /*
         * PCA9685_OSC_CLOCK_MHZ is 25, i.e. an integer divider of 1000.
         * The following calculation is therefore only a multiplication
         * and we are not losing precision.
         */
        state->period = (PCA9685_COUNTER_RANGE * 1000 / PCA9685_OSC_CLOCK_MHZ) *
                        (val + 1);

        /* The (per-channel) polarity is fixed */
        state->polarity = PWM_POLARITY_NORMAL;

        if (pwm->hwpwm >= PCA9685_MAXCHAN) {
                /*
                 * The "all LEDs" channel does not support HW readout
                 * Return 0 and disabled for backwards compatibility
                 */
                state->duty_cycle = 0;
                state->enabled = false;
                return;
        }

        state->enabled = true;
        duty = pca9685_pwm_get_duty(pca, pwm->hwpwm);
        state->duty_cycle = DIV_ROUND_DOWN_ULL(duty * state->period, PCA9685_COUNTER_RANGE);
}

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

        if (pca9685_pwm_test_and_set_inuse(pca, pwm->hwpwm))
                return -EBUSY;

        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(chip->dev);

        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);
        pca9685_pwm_set_duty(pca, pwm->hwpwm, 0);
        clear_bit(pwm->hwpwm, pca->pwms_enabled);
        mutex_unlock(&pca->lock);

        pm_runtime_put(chip->dev);
        pca9685_pwm_clear_inuse(pca, pwm->hwpwm);
}

static const struct pwm_ops pca9685_pwm_ops = {
        .apply = pca9685_pwm_apply,
        .get_state = pca9685_pwm_get_state,
        .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;
        unsigned int reg;
        int ret;

        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;
        }

        i2c_set_clientdata(client, pca);

        mutex_init(&pca->lock);

        ret = pca9685_read_reg(pca, PCA9685_MODE2, &reg);
        if (ret)
                return ret;

        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(pca, PCA9685_MODE2, reg);
        if (ret)
                return ret;

        /* Disable all LED ALLCALL and SUBx addresses to avoid bus collisions */
        pca9685_read_reg(pca, PCA9685_MODE1, &reg);
        reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
        pca9685_write_reg(pca, PCA9685_MODE1, reg);

        /* Reset OFF/ON registers to POR default */
        pca9685_write_reg(pca, PCA9685_ALL_LED_OFF_L, LED_FULL);
        pca9685_write_reg(pca, PCA9685_ALL_LED_OFF_H, LED_FULL);
        pca9685_write_reg(pca, PCA9685_ALL_LED_ON_L, 0);
        pca9685_write_reg(pca, PCA9685_ALL_LED_ON_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;

        ret = pwmchip_add(&pca->chip);
        if (ret < 0)
                return ret;

        ret = pca9685_pwm_gpio_probe(pca);
        if (ret < 0) {
                pwmchip_remove(&pca->chip);
                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(pca, true);
                pm_runtime_set_suspended(&client->dev);
        } else {
                /* Wake the chip up if runtime PM is disabled */
                pca9685_set_sleep_mode(pca, false);
        }

        return 0;
}

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

        pwmchip_remove(&pca->chip);

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

        pm_runtime_disable(&client->dev);

        return 0;
}

static int __maybe_unused pca9685_pwm_runtime_suspend(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct pca9685 *pca = i2c_get_clientdata(client);

        pca9685_set_sleep_mode(pca, true);
        return 0;
}

static int __maybe_unused pca9685_pwm_runtime_resume(struct device *dev)
{
        struct i2c_client *client = to_i2c_client(dev);
        struct pca9685 *pca = i2c_get_clientdata(client);

        pca9685_set_sleep_mode(pca, false);
        return 0;
}

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 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 = ACPI_PTR(pca9685_acpi_ids),
                .of_match_table = of_match_ptr(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");