/* $NetBSD: pwmregulator.c,v 1.4 2024/02/07 04:20:28 msaitoh Exp $ */

/*
* Copyright (c) 2020 Ryo Shimizu
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
* OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: pwmregulator.c,v 1.4 2024/02/07 04:20:28 msaitoh Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/kmem.h>

#include <dev/fdt/fdtvar.h>
#include <dev/pwm/pwmvar.h>

static int pwmregulator_match(device_t, cfdata_t, void *);
static void pwmregulator_attach(device_t, device_t, void *);

/* fdtbus_regulator_controller_func callback */
static int pwmregulator_acquire(device_t);
static void pwmregulator_release(device_t);
static int pwmregulator_enable(device_t, bool);
static int pwmregulator_set_voltage(device_t, u_int, u_int);
static int pwmregulator_get_voltage(device_t, u_int *);

static const struct fdtbus_regulator_controller_func pwmregulator_funcs = {
       .acquire = pwmregulator_acquire,
       .release = pwmregulator_release,
       .enable = pwmregulator_enable,
       .set_voltage = pwmregulator_set_voltage,
       .get_voltage = pwmregulator_get_voltage
};

struct voltage_duty {
       uint32_t microvolt;
       uint32_t duty;          /* percentage; 0-100 */
};

struct pwmregulator_softc {
       device_t sc_dev;
       pwm_tag_t sc_pwm;
       struct fdtbus_gpio_pin *sc_pin;
       struct voltage_duty *sc_voltage_table;
       int sc_voltage_table_num;
       int sc_phandle;
       uint32_t sc_microvolt_min;
       uint32_t sc_microvolt_max;
       uint32_t sc_dutycycle_unit;
       uint32_t sc_dutycycle_range[2];
       bool sc_always_on;
       bool sc_boot_on;
};

CFATTACH_DECL_NEW(pregulator, sizeof(struct pwmregulator_softc),
   pwmregulator_match, pwmregulator_attach, NULL, NULL);

static const struct device_compatible_entry compat_data[] = {
       { .compat = "pwm-regulator" },
       DEVICE_COMPAT_EOL
};

static int
pwmregulator_match(device_t parent, cfdata_t cf, void *aux)
{
       const struct fdt_attach_args *faa = aux;

       return of_compatible_match(faa->faa_phandle, compat_data);
}

static void
pwmregulator_attach(device_t parent, device_t self, void *aux)
{
       struct pwmregulator_softc * const sc = device_private(self);
       const struct fdt_attach_args *faa = aux;
       const int phandle = faa->faa_phandle;
       int len;
       char *name;

       sc->sc_dev = self;
       sc->sc_phandle = phandle;

       aprint_naive("\n");
       len = OF_getproplen(phandle, "regulator-name");
       if (len > 0) {
               name = kmem_zalloc(len, KM_SLEEP);
               if (OF_getprop(phandle, "regulator-name", name, len) == len)
                       aprint_normal(": %s\n", name);
               else
                       aprint_normal("\n");
               kmem_free(name, len);
       } else {
               aprint_normal("\n");
       }

       if (of_getprop_uint32(phandle, "regulator-min-microvolt",
           &sc->sc_microvolt_min) != 0) {
               aprint_error_dev(sc->sc_dev,
                   "missing regulator-min-microvolt properties\n");
               return;
       }
       if (of_getprop_uint32(phandle, "regulator-max-microvolt",
           &sc->sc_microvolt_max) != 0) {
               aprint_error_dev(sc->sc_dev,
                   "missing regulator-max-microvolt properties\n");
               return;
       }

       if (of_getprop_uint32(phandle, "pwm-dutycycle-unit",
           &sc->sc_dutycycle_unit) != 0)
               sc->sc_dutycycle_unit = 100;

       if (of_getprop_uint32_array(phandle, "pwm-dutycycle-range",
           sc->sc_dutycycle_range, 2) != 0) {
               sc->sc_dutycycle_range[0] = 0;
               sc->sc_dutycycle_range[1] = 100;
       }

       len = OF_getproplen(phandle, "voltage-table");
       if (len > 0) {
               struct voltage_duty *voltage_table = kmem_zalloc(len, KM_SLEEP);
               if (of_getprop_uint32_array(phandle, "voltage-table",
                   (uint32_t *)voltage_table, len / sizeof(uint32_t)) == 0) {
                       sc->sc_voltage_table = voltage_table;
                       sc->sc_voltage_table_num =
                           len / sizeof(struct voltage_duty);
#ifdef PWMREGULATOR_DEBUG
                       for (int i = 0; i < sc->sc_voltage_table_num; i++) {
                               aprint_debug_dev(sc->sc_dev,
                                   "VoltageTable[%d]: %uuV = Duty:%u%%\n", i,
                                   voltage_table[i].voltage,
                                   voltage_table[i].duty);
                       }
#endif
                       /*
                        * if voltage-table is provided, the duty in the table
                        * represents a percentage, i.e. 0-100%, so
                        * dutycycle_unit is 100.
                        */
                       sc->sc_dutycycle_unit = 100;
               } else {
                       kmem_free(sc->sc_voltage_table, len);
               }
       }
#ifdef PWMREGULATOR_DEBUG
       if (sc->sc_voltage_table_num == 0) {
               aprint_debug_dev(sc->sc_dev, "Duty:%u%%=%uuV, Duty:%u%%=%uuV\n",
                   sc->sc_dutycycle_range[0], sc->sc_microvolt_min,
                   sc->sc_dutycycle_range[1], sc->sc_microvolt_max);
       }
#endif

       sc->sc_always_on = of_getprop_bool(phandle, "regulator-always-on");
       sc->sc_boot_on = of_getprop_bool(phandle, "regulator-boot-on");

       fdtbus_register_regulator_controller(self, phandle,
           &pwmregulator_funcs);

       /*
        * If the regulator is flagged as always on or enabled at boot,
        * ensure that it is enabled
        */
       if (sc->sc_always_on || sc->sc_boot_on)
               pwmregulator_enable(self, true);
}

static int
pwmregulator_acquire(device_t dev)
{
       struct pwmregulator_softc * const sc = device_private(dev);

       /* "enable-gpios" is optional */
       sc->sc_pin = fdtbus_gpio_acquire(sc->sc_phandle, "enable-gpios",
           GPIO_PIN_OUTPUT);

       sc->sc_pwm = fdtbus_pwm_acquire(sc->sc_phandle, "pwms");
       if (sc->sc_pwm == NULL)
               return ENXIO;

       return 0;
}

static void
pwmregulator_release(device_t dev)
{
       struct pwmregulator_softc * const sc = device_private(dev);

       if (sc->sc_pin != NULL) {
               fdtbus_gpio_write(sc->sc_pin, 0);
               fdtbus_gpio_release(sc->sc_pin);
       }

       sc->sc_pwm = NULL;
}

static int
pwmregulator_enable(device_t dev, bool enable)
{
       struct pwmregulator_softc * const sc = device_private(dev);
       int error;

       if (sc->sc_pwm == NULL)
               return ENXIO;

       if (enable) {
               if (sc->sc_pin != NULL)
                       fdtbus_gpio_write(sc->sc_pin, 1);
               error = pwm_enable(sc->sc_pwm);
       } else {
               error = pwm_disable(sc->sc_pwm);
               if (sc->sc_pin != NULL)
                       fdtbus_gpio_write(sc->sc_pin, 0);
       }

       return error;
}

static int
pwmregulator_set_voltage(device_t dev, u_int min_uvolt, u_int max_uvolt)
{
       struct pwmregulator_softc * const sc = device_private(dev);
       struct pwm_config conf;
       int duty, d0, d1, v0, v1, uv, rc;

       if (sc->sc_pwm == NULL)
               return ENXIO;

       rc = pwm_get_config(sc->sc_pwm, &conf);
       if (rc != 0) {
               device_printf(dev, "%s: couldn't get pwm config, error=%d\n",
                   __func__, rc);
               return rc;
       }

       uv = (min_uvolt + max_uvolt) / 2;

       if (sc->sc_voltage_table_num > 0) {
               /* find the nearest duty from voltage-table */
               int i, bestidx = 0;
               for (i = 1; i < sc->sc_voltage_table_num; i++) {
                       if (abs(sc->sc_voltage_table[i].microvolt - uv) <
                           abs(sc->sc_voltage_table[bestidx].microvolt - uv))
                               bestidx = i;
               }
               duty = sc->sc_voltage_table[bestidx].duty;
       } else {
               /* calculate duty from voltage */
               v0 = sc->sc_microvolt_min;
               v1 = sc->sc_microvolt_max;
               d0 = sc->sc_dutycycle_range[0];
               d1 = sc->sc_dutycycle_range[1];
               duty = (uv - v0) * (d1 - d0) / (v1 - v0) + d0;
       }

       conf.duty_cycle = duty * conf.period / sc->sc_dutycycle_unit;

       rc = pwm_set_config(sc->sc_pwm, &conf);
       if (rc != 0)
               device_printf(dev, "couldn't set pwm config, error=%d\n", rc);
       return rc;
}

static int
pwmregulator_get_voltage(device_t dev, u_int *puvolt)
{
       struct pwmregulator_softc * const sc = device_private(dev);
       struct pwm_config conf;
       int duty, d0, d1, v0, v1, uv, rc;

       if (sc->sc_pwm == NULL)
               return ENXIO;

       rc = pwm_get_config(sc->sc_pwm, &conf);
       if (rc != 0) {
               device_printf(dev, "%s: couldn't get pwm config, error=%d\n",
                   __func__, rc);
               return rc;
       }

       duty = conf.duty_cycle * sc->sc_dutycycle_unit / conf.period;

       if (sc->sc_voltage_table_num > 0) {
               /* find the nearest voltage from voltage-table */
               int i, bestidx = 0;
               for (i = 1; i < sc->sc_voltage_table_num; i++) {
                       if (abs(sc->sc_voltage_table[i].duty - duty) <
                           abs(sc->sc_voltage_table[bestidx].duty - duty))
                               bestidx = i;
               }
               uv = sc->sc_voltage_table[bestidx].microvolt;
       } else {
               /* calculate voltage from duty */
               d0 = sc->sc_dutycycle_range[0];
               d1 = sc->sc_dutycycle_range[1];
               v0 = sc->sc_microvolt_min;
               v1 = sc->sc_microvolt_max;
               uv = (duty - d0) * (v1 - v0) / (d1 - d0)  + v0;
       }

       *puvolt = uv;
       return 0;
}

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