// SPDX-License-Identifier: GPL-2.0
/*
 * Helper functions for MMC regulators.
 */

#include <linux/device.h>
#include <linux/err.h>
#include <linux/log2.h>
#include <linux/regulator/consumer.h>
#include <linux/workqueue.h>

#include <linux/mmc/host.h>

#include "core.h"
#include "host.h"

#ifdef CONFIG_REGULATOR

/**
 * mmc_ocrbitnum_to_vdd - Convert a OCR bit number to its voltage
 * @vdd_bit:    OCR bit number
 * @min_uV:     minimum voltage value (mV)
 * @max_uV:     maximum voltage value (mV)
 *
 * This function returns the voltage range according to the provided OCR
 * bit number. If conversion is not possible a negative errno value returned.
 */
static int mmc_ocrbitnum_to_vdd(int vdd_bit, int *min_uV, int *max_uV)
{
        int             tmp;

        if (!vdd_bit)
                return -EINVAL;

        /*
         * REVISIT mmc_vddrange_to_ocrmask() may have set some
         * bits this regulator doesn't quite support ... don't
         * be too picky, most cards and regulators are OK with
         * a 0.1V range goof (it's a small error percentage).
         */
        tmp = vdd_bit - ilog2(MMC_VDD_165_195);
        if (tmp == 0) {
                *min_uV = 1650 * 1000;
                *max_uV = 1950 * 1000;
        } else {
                *min_uV = 1900 * 1000 + tmp * 100 * 1000;
                *max_uV = *min_uV + 100 * 1000;
        }

        return 0;
}

/**
 * mmc_regulator_get_ocrmask - return mask of supported voltages
 * @supply: regulator to use
 *
 * This returns either a negative errno, or a mask of voltages that
 * can be provided to MMC/SD/SDIO devices using the specified voltage
 * regulator.  This would normally be called before registering the
 * MMC host adapter.
 */
static int mmc_regulator_get_ocrmask(struct regulator *supply)
{
        int                     result = 0;
        int                     count;
        int                     i;
        int                     vdd_uV;
        int                     vdd_mV;

        count = regulator_count_voltages(supply);
        if (count < 0)
                return count;

        for (i = 0; i < count; i++) {
                vdd_uV = regulator_list_voltage(supply, i);
                if (vdd_uV <= 0)
                        continue;

                vdd_mV = vdd_uV / 1000;
                result |= mmc_vddrange_to_ocrmask(vdd_mV, vdd_mV);
        }

        if (!result) {
                vdd_uV = regulator_get_voltage(supply);
                if (vdd_uV <= 0)
                        return vdd_uV;

                vdd_mV = vdd_uV / 1000;
                result = mmc_vddrange_to_ocrmask(vdd_mV, vdd_mV);
        }

        return result;
}

/**
 * mmc_regulator_set_ocr - set regulator to match host->ios voltage
 * @mmc: the host to regulate
 * @supply: regulator to use
 * @vdd_bit: zero for power off, else a bit number (host->ios.vdd)
 *
 * Returns zero on success, else negative errno.
 *
 * MMC host drivers may use this to enable or disable a regulator using
 * a particular supply voltage.  This would normally be called from the
 * set_ios() method.
 */
int mmc_regulator_set_ocr(struct mmc_host *mmc,
                        struct regulator *supply,
                        unsigned short vdd_bit)
{
        int                     result = 0;
        int                     min_uV, max_uV;

        if (IS_ERR(supply))
                return 0;

        if (vdd_bit) {
                mmc_ocrbitnum_to_vdd(vdd_bit, &min_uV, &max_uV);

                result = regulator_set_voltage(supply, min_uV, max_uV);
                if (result == 0 && !mmc->regulator_enabled) {
                        result = regulator_enable(supply);
                        if (!result)
                                mmc->regulator_enabled = true;
                }
        } else if (mmc->regulator_enabled) {
                result = regulator_disable(supply);
                if (result == 0)
                        mmc->regulator_enabled = false;
        }

        if (result)
                dev_err(mmc_dev(mmc),
                        "could not set regulator OCR (%d)\n", result);
        return result;
}
EXPORT_SYMBOL_GPL(mmc_regulator_set_ocr);

static int mmc_regulator_set_voltage_if_supported(struct regulator *regulator,
                                                  int min_uV, int target_uV,
                                                  int max_uV)
{
        int current_uV;

        /*
         * Check if supported first to avoid errors since we may try several
         * signal levels during power up and don't want to show errors.
         */
        if (!regulator_is_supported_voltage(regulator, min_uV, max_uV))
                return -EINVAL;

        /*
         * The voltage is already set, no need to switch.
         * Return 1 to indicate that no switch happened.
         */
        current_uV = regulator_get_voltage(regulator);
        if (current_uV == target_uV)
                return 1;

        return regulator_set_voltage_triplet(regulator, min_uV, target_uV,
                                             max_uV);
}

/**
 * mmc_regulator_set_vqmmc - Set VQMMC as per the ios
 * @mmc: the host to regulate
 * @ios: io bus settings
 *
 * For 3.3V signaling, we try to match VQMMC to VMMC as closely as possible.
 * That will match the behavior of old boards where VQMMC and VMMC were supplied
 * by the same supply.  The Bus Operating conditions for 3.3V signaling in the
 * SD card spec also define VQMMC in terms of VMMC.
 * If this is not possible we'll try the full 2.7-3.6V of the spec.
 *
 * For 1.2V and 1.8V signaling we'll try to get as close as possible to the
 * requested voltage.  This is definitely a good idea for UHS where there's a
 * separate regulator on the card that's trying to make 1.8V and it's best if
 * we match.
 *
 * This function is expected to be used by a controller's
 * start_signal_voltage_switch() function.
 */
int mmc_regulator_set_vqmmc(struct mmc_host *mmc, struct mmc_ios *ios)
{
        struct device *dev = mmc_dev(mmc);
        int ret, volt, min_uV, max_uV;

        /* If no vqmmc supply then we can't change the voltage */
        if (IS_ERR(mmc->supply.vqmmc))
                return -EINVAL;

        switch (ios->signal_voltage) {
        case MMC_SIGNAL_VOLTAGE_120:
                return mmc_regulator_set_voltage_if_supported(mmc->supply.vqmmc,
                                                1100000, 1200000, 1300000);
        case MMC_SIGNAL_VOLTAGE_180:
                return mmc_regulator_set_voltage_if_supported(mmc->supply.vqmmc,
                                                1700000, 1800000, 1950000);
        case MMC_SIGNAL_VOLTAGE_330:
                ret = mmc_ocrbitnum_to_vdd(mmc->ios.vdd, &volt, &max_uV);
                if (ret < 0)
                        return ret;

                dev_dbg(dev, "%s: found vmmc voltage range of %d-%duV\n",
                        __func__, volt, max_uV);

                min_uV = max(volt - 300000, 2700000);
                max_uV = min(max_uV + 200000, 3600000);

                /*
                 * Due to a limitation in the current implementation of
                 * regulator_set_voltage_triplet() which is taking the lowest
                 * voltage possible if below the target, search for a suitable
                 * voltage in two steps and try to stay close to vmmc
                 * with a 0.3V tolerance at first.
                 */
                ret = mmc_regulator_set_voltage_if_supported(mmc->supply.vqmmc,
                                                        min_uV, volt, max_uV);
                if (ret >= 0)
                        return ret;

                return mmc_regulator_set_voltage_if_supported(mmc->supply.vqmmc,
                                                2700000, volt, 3600000);
        default:
                return -EINVAL;
        }
}
EXPORT_SYMBOL_GPL(mmc_regulator_set_vqmmc);

/**
 * mmc_regulator_set_vqmmc2 - Set vqmmc2 as per the ios->vqmmc2_voltage
 * @mmc: The mmc host to regulate
 * @ios: The io bus settings
 *
 * Sets a new voltage level for the vqmmc2 regulator, which may correspond to
 * the vdd2 regulator for an SD UHS-II interface. This function is expected to
 * be called by mmc host drivers.
 *
 * Returns a negative error code on failure, zero if the voltage level was
 * changed successfully or a positive value if the level didn't need to change.
 */
int mmc_regulator_set_vqmmc2(struct mmc_host *mmc, struct mmc_ios *ios)
{
        if (IS_ERR(mmc->supply.vqmmc2))
                return -EINVAL;

        switch (ios->vqmmc2_voltage) {
        case MMC_VQMMC2_VOLTAGE_180:
                return mmc_regulator_set_voltage_if_supported(
                        mmc->supply.vqmmc2, 1700000, 1800000, 1950000);
        default:
                return -EINVAL;
        }
}
EXPORT_SYMBOL_GPL(mmc_regulator_set_vqmmc2);

#else

static inline int mmc_regulator_get_ocrmask(struct regulator *supply)
{
        return 0;
}

#endif /* CONFIG_REGULATOR */

/* To be called from a high-priority workqueue */
void mmc_undervoltage_workfn(struct work_struct *work)
{
        struct mmc_supply *supply;
        struct mmc_host *host;

        supply = container_of(work, struct mmc_supply, uv_work);
        host = container_of(supply, struct mmc_host, supply);

        mmc_handle_undervoltage(host);
}

static int mmc_handle_regulator_event(struct notifier_block *nb,
                                      unsigned long event, void *data)
{
        struct mmc_supply *supply = container_of(nb, struct mmc_supply,
                                                 vmmc_nb);
        struct mmc_host *host = container_of(supply, struct mmc_host, supply);
        unsigned long flags;

        switch (event) {
        case REGULATOR_EVENT_UNDER_VOLTAGE:
                spin_lock_irqsave(&host->lock, flags);
                if (host->undervoltage) {
                        spin_unlock_irqrestore(&host->lock, flags);
                        return NOTIFY_OK;
                }

                host->undervoltage = true;
                spin_unlock_irqrestore(&host->lock, flags);

                queue_work(system_highpri_wq, &host->supply.uv_work);
                break;
        default:
                return NOTIFY_DONE;
        }

        return NOTIFY_OK;
}

/**
 * mmc_regulator_register_undervoltage_notifier - Register for undervoltage
 *                                                events
 * @host: MMC host
 *
 * To be called by a bus driver when a card supporting graceful shutdown
 * is attached.
 */
void mmc_regulator_register_undervoltage_notifier(struct mmc_host *host)
{
        int ret;

        if (IS_ERR_OR_NULL(host->supply.vmmc))
                return;

        host->supply.vmmc_nb.notifier_call = mmc_handle_regulator_event;
        ret = regulator_register_notifier(host->supply.vmmc,
                                          &host->supply.vmmc_nb);
        if (ret)
                dev_warn(mmc_dev(host), "Failed to register vmmc notifier: %d\n", ret);
}

/**
 * mmc_regulator_unregister_undervoltage_notifier - Unregister undervoltage
 *                                                  notifier
 * @host: MMC host
 */
void mmc_regulator_unregister_undervoltage_notifier(struct mmc_host *host)
{
        if (IS_ERR_OR_NULL(host->supply.vmmc))
                return;

        regulator_unregister_notifier(host->supply.vmmc, &host->supply.vmmc_nb);
        cancel_work_sync(&host->supply.uv_work);
}

/**
 * mmc_regulator_get_supply - try to get VMMC and VQMMC regulators for a host
 * @mmc: the host to regulate
 *
 * Returns 0 or errno. errno should be handled, it is either a critical error
 * or -EPROBE_DEFER. 0 means no critical error but it does not mean all
 * regulators have been found because they all are optional. If you require
 * certain regulators, you need to check separately in your driver if they got
 * populated after calling this function.
 */
int mmc_regulator_get_supply(struct mmc_host *mmc)
{
        struct device *dev = mmc_dev(mmc);
        int ret;

        mmc->supply.vmmc = devm_regulator_get_optional(dev, "vmmc");
        mmc->supply.vqmmc = devm_regulator_get_optional(dev, "vqmmc");
        mmc->supply.vqmmc2 = devm_regulator_get_optional(dev, "vqmmc2");

        if (IS_ERR(mmc->supply.vmmc)) {
                if (PTR_ERR(mmc->supply.vmmc) == -EPROBE_DEFER)
                        return dev_err_probe(dev, -EPROBE_DEFER,
                                             "vmmc regulator not available\n");

                dev_dbg(dev, "No vmmc regulator found\n");
        } else {
                ret = mmc_regulator_get_ocrmask(mmc->supply.vmmc);
                if (ret > 0)
                        mmc->ocr_avail = ret;
                else
                        dev_warn(dev, "Failed getting OCR mask: %d\n", ret);
        }

        if (IS_ERR(mmc->supply.vqmmc)) {
                if (PTR_ERR(mmc->supply.vqmmc) == -EPROBE_DEFER)
                        return dev_err_probe(dev, -EPROBE_DEFER,
                                             "vqmmc regulator not available\n");

                dev_dbg(dev, "No vqmmc regulator found\n");
        }

        if (IS_ERR(mmc->supply.vqmmc2)) {
                if (PTR_ERR(mmc->supply.vqmmc2) == -EPROBE_DEFER)
                        return -EPROBE_DEFER;
                dev_dbg(dev, "No vqmmc2 regulator found\n");
        }

        return 0;
}
EXPORT_SYMBOL_GPL(mmc_regulator_get_supply);

/**
 * mmc_regulator_enable_vqmmc - enable VQMMC regulator for a host
 * @mmc: the host to regulate
 *
 * Returns 0 or errno. Enables the regulator for vqmmc.
 * Keeps track of the enable status for ensuring that calls to
 * regulator_enable/disable are balanced.
 */
int mmc_regulator_enable_vqmmc(struct mmc_host *mmc)
{
        int ret = 0;

        if (!IS_ERR(mmc->supply.vqmmc) && !mmc->vqmmc_enabled) {
                ret = regulator_enable(mmc->supply.vqmmc);
                if (ret < 0)
                        dev_err(mmc_dev(mmc), "enabling vqmmc regulator failed\n");
                else
                        mmc->vqmmc_enabled = true;
        }

        return ret;
}
EXPORT_SYMBOL_GPL(mmc_regulator_enable_vqmmc);

/**
 * mmc_regulator_disable_vqmmc - disable VQMMC regulator for a host
 * @mmc: the host to regulate
 *
 * Returns 0 or errno. Disables the regulator for vqmmc.
 * Keeps track of the enable status for ensuring that calls to
 * regulator_enable/disable are balanced.
 */
void mmc_regulator_disable_vqmmc(struct mmc_host *mmc)
{
        if (!IS_ERR(mmc->supply.vqmmc) && mmc->vqmmc_enabled) {
                regulator_disable(mmc->supply.vqmmc);
                mmc->vqmmc_enabled = false;
        }
}
EXPORT_SYMBOL_GPL(mmc_regulator_disable_vqmmc);