// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2015, 2017-2018, 2022, The Linux Foundation. All rights reserved.
 */

#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/ktime.h>
#include <linux/pm_domain.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
#include <linux/reset-controller.h>
#include <linux/slab.h>
#include "gdsc.h"

#define PWR_ON_MASK             BIT(31)
#define EN_REST_WAIT_MASK       GENMASK_ULL(23, 20)
#define EN_FEW_WAIT_MASK        GENMASK_ULL(19, 16)
#define CLK_DIS_WAIT_MASK       GENMASK_ULL(15, 12)
#define SW_OVERRIDE_MASK        BIT(2)
#define HW_CONTROL_MASK         BIT(1)
#define SW_COLLAPSE_MASK        BIT(0)
#define GMEM_CLAMP_IO_MASK      BIT(0)
#define GMEM_RESET_MASK         BIT(4)

/* CFG_GDSCR */
#define GDSC_POWER_UP_COMPLETE          BIT(16)
#define GDSC_POWER_DOWN_COMPLETE        BIT(15)
#define GDSC_RETAIN_FF_ENABLE           BIT(11)
#define CFG_GDSCR_OFFSET                0x4

/* Wait 2^n CXO cycles between all states. Here, n=2 (4 cycles). */
#define EN_REST_WAIT_VAL        0x2
#define EN_FEW_WAIT_VAL         0x8
#define CLK_DIS_WAIT_VAL        0x2

/* Transition delay shifts */
#define EN_REST_WAIT_SHIFT      20
#define EN_FEW_WAIT_SHIFT       16
#define CLK_DIS_WAIT_SHIFT      12

#define RETAIN_MEM              BIT(14)
#define RETAIN_PERIPH           BIT(13)

#define STATUS_POLL_TIMEOUT_US  2000
#define TIMEOUT_US              500

#define domain_to_gdsc(domain) container_of(domain, struct gdsc, pd)

enum gdsc_status {
        GDSC_OFF,
        GDSC_ON
};

/* Returns 1 if GDSC status is status, 0 if not, and < 0 on error */
static int gdsc_check_status(struct gdsc *sc, enum gdsc_status status)
{
        unsigned int reg;
        u32 val;
        int ret;

        if (sc->flags & POLL_CFG_GDSCR)
                reg = sc->gdscr + CFG_GDSCR_OFFSET;
        else if (sc->gds_hw_ctrl)
                reg = sc->gds_hw_ctrl;
        else
                reg = sc->gdscr;

        ret = regmap_read(sc->regmap, reg, &val);
        if (ret)
                return ret;

        if (sc->flags & POLL_CFG_GDSCR) {
                switch (status) {
                case GDSC_ON:
                        return !!(val & GDSC_POWER_UP_COMPLETE);
                case GDSC_OFF:
                        return !!(val & GDSC_POWER_DOWN_COMPLETE);
                }
        }

        switch (status) {
        case GDSC_ON:
                return !!(val & PWR_ON_MASK);
        case GDSC_OFF:
                return !(val & PWR_ON_MASK);
        }

        return -EINVAL;
}

static int gdsc_hwctrl(struct gdsc *sc, bool en)
{
        u32 val = en ? HW_CONTROL_MASK : 0;

        return regmap_update_bits(sc->regmap, sc->gdscr, HW_CONTROL_MASK, val);
}

static int gdsc_poll_status(struct gdsc *sc, enum gdsc_status status)
{
        ktime_t start;

        start = ktime_get();
        do {
                if (gdsc_check_status(sc, status))
                        return 0;
        } while (ktime_us_delta(ktime_get(), start) < STATUS_POLL_TIMEOUT_US);

        if (gdsc_check_status(sc, status))
                return 0;

        return -ETIMEDOUT;
}

static int gdsc_update_collapse_bit(struct gdsc *sc, bool val)
{
        u32 reg, mask;
        int ret;

        if (sc->collapse_mask) {
                reg = sc->collapse_ctrl;
                mask = sc->collapse_mask;
        } else {
                reg = sc->gdscr;
                mask = SW_COLLAPSE_MASK;
        }

        ret = regmap_update_bits(sc->regmap, reg, mask, val ? mask : 0);
        if (ret)
                return ret;

        return 0;
}

static int gdsc_toggle_logic(struct gdsc *sc, enum gdsc_status status,
                bool wait)
{
        int ret;

        if (status == GDSC_ON && sc->rsupply) {
                ret = regulator_enable(sc->rsupply);
                if (ret < 0)
                        return ret;
        }

        ret = gdsc_update_collapse_bit(sc, status == GDSC_OFF);

        /* If disabling votable gdscs, don't poll on status */
        if ((sc->flags & VOTABLE) && status == GDSC_OFF && !wait) {
                /*
                 * Add a short delay here to ensure that an enable
                 * right after it was disabled does not put it in an
                 * unknown state
                 */
                udelay(TIMEOUT_US);
                return 0;
        }

        if (sc->gds_hw_ctrl) {
                /*
                 * The gds hw controller asserts/de-asserts the status bit soon
                 * after it receives a power on/off request from a master.
                 * The controller then takes around 8 xo cycles to start its
                 * internal state machine and update the status bit. During
                 * this time, the status bit does not reflect the true status
                 * of the core.
                 * Add a delay of 1 us between writing to the SW_COLLAPSE bit
                 * and polling the status bit.
                 */
                udelay(1);
        }

        ret = gdsc_poll_status(sc, status);
        WARN(ret, "%s status stuck at 'o%s'", sc->pd.name, status ? "ff" : "n");

        if (!ret && status == GDSC_OFF && sc->rsupply) {
                ret = regulator_disable(sc->rsupply);
                if (ret < 0)
                        return ret;
        }

        return ret;
}

static inline int gdsc_deassert_reset(struct gdsc *sc)
{
        int i;

        for (i = 0; i < sc->reset_count; i++)
                sc->rcdev->ops->deassert(sc->rcdev, sc->resets[i]);
        return 0;
}

static inline int gdsc_assert_reset(struct gdsc *sc)
{
        int i;

        for (i = 0; i < sc->reset_count; i++)
                sc->rcdev->ops->assert(sc->rcdev, sc->resets[i]);
        return 0;
}

static inline void gdsc_force_mem_on(struct gdsc *sc)
{
        int i;
        u32 mask = RETAIN_MEM;

        if (!(sc->flags & NO_RET_PERIPH))
                mask |= RETAIN_PERIPH;

        for (i = 0; i < sc->cxc_count; i++)
                regmap_update_bits(sc->regmap, sc->cxcs[i], mask, mask);
}

static inline void gdsc_clear_mem_on(struct gdsc *sc)
{
        int i;
        u32 mask = RETAIN_MEM;

        if (!(sc->flags & NO_RET_PERIPH))
                mask |= RETAIN_PERIPH;

        for (i = 0; i < sc->cxc_count; i++)
                regmap_update_bits(sc->regmap, sc->cxcs[i], mask, 0);
}

static inline void gdsc_deassert_clamp_io(struct gdsc *sc)
{
        regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
                           GMEM_CLAMP_IO_MASK, 0);
}

static inline void gdsc_assert_clamp_io(struct gdsc *sc)
{
        regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
                           GMEM_CLAMP_IO_MASK, 1);
}

static inline void gdsc_assert_reset_aon(struct gdsc *sc)
{
        regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
                           GMEM_RESET_MASK, 1);
        udelay(1);
        regmap_update_bits(sc->regmap, sc->clamp_io_ctrl,
                           GMEM_RESET_MASK, 0);
}

static void gdsc_retain_ff_on(struct gdsc *sc)
{
        u32 mask = GDSC_RETAIN_FF_ENABLE;

        regmap_update_bits(sc->regmap, sc->gdscr, mask, mask);
}

static int gdsc_enable(struct generic_pm_domain *domain)
{
        struct gdsc *sc = domain_to_gdsc(domain);
        int ret;

        if (sc->pwrsts == PWRSTS_ON)
                return gdsc_deassert_reset(sc);

        if (sc->flags & SW_RESET) {
                gdsc_assert_reset(sc);
                udelay(1);
                gdsc_deassert_reset(sc);
        }

        if (sc->flags & CLAMP_IO) {
                if (sc->flags & AON_RESET)
                        gdsc_assert_reset_aon(sc);
                gdsc_deassert_clamp_io(sc);
        }

        ret = gdsc_toggle_logic(sc, GDSC_ON, false);
        if (ret)
                return ret;

        if (sc->pwrsts & PWRSTS_OFF)
                gdsc_force_mem_on(sc);

        /*
         * If clocks to this power domain were already on, they will take an
         * additional 4 clock cycles to re-enable after the power domain is
         * enabled. Delay to account for this. A delay is also needed to ensure
         * clocks are not enabled within 400ns of enabling power to the
         * memories.
         */
        udelay(1);

        if (sc->flags & RETAIN_FF_ENABLE)
                gdsc_retain_ff_on(sc);

        /* Turn on HW trigger mode if supported */
        if (sc->flags & HW_CTRL) {
                ret = gdsc_hwctrl(sc, true);
                if (ret)
                        return ret;
                /*
                 * Wait for the GDSC to go through a power down and
                 * up cycle.  In case a firmware ends up polling status
                 * bits for the gdsc, it might read an 'on' status before
                 * the GDSC can finish the power cycle.
                 * We wait 1us before returning to ensure the firmware
                 * can't immediately poll the status bits.
                 */
                udelay(1);
        }

        return 0;
}

static int gdsc_disable(struct generic_pm_domain *domain)
{
        struct gdsc *sc = domain_to_gdsc(domain);
        int ret;

        if (sc->pwrsts == PWRSTS_ON)
                return gdsc_assert_reset(sc);

        /* Turn off HW trigger mode if supported */
        if (sc->flags & HW_CTRL) {
                ret = gdsc_hwctrl(sc, false);
                if (ret < 0)
                        return ret;
                /*
                 * Wait for the GDSC to go through a power down and
                 * up cycle.  In case we end up polling status
                 * bits for the gdsc before the power cycle is completed
                 * it might read an 'on' status wrongly.
                 */
                udelay(1);

                ret = gdsc_poll_status(sc, GDSC_ON);
                if (ret)
                        return ret;
        }

        if (sc->pwrsts & PWRSTS_OFF)
                gdsc_clear_mem_on(sc);

        /*
         * If the GDSC supports only a Retention state, apart from ON,
         * leave it in ON state.
         * There is no SW control to transition the GDSC into
         * Retention state. This happens in HW when the parent
         * domain goes down to a Low power state
         */
        if (sc->pwrsts == PWRSTS_RET_ON)
                return 0;

        ret = gdsc_toggle_logic(sc, GDSC_OFF, domain->synced_poweroff);
        if (ret)
                return ret;

        if (sc->flags & CLAMP_IO)
                gdsc_assert_clamp_io(sc);

        return 0;
}

static int gdsc_set_hwmode(struct generic_pm_domain *domain, struct device *dev, bool mode)
{
        struct gdsc *sc = domain_to_gdsc(domain);
        int ret;

        ret = gdsc_hwctrl(sc, mode);
        if (ret)
                return ret;

        /*
         * Wait for the GDSC to go through a power down and
         * up cycle. If we poll the status register before the
         * power cycle is finished we might read incorrect values.
         */
        udelay(1);

        /*
         * When the GDSC is switched to HW mode, HW can disable the GDSC.
         * When the GDSC is switched back to SW mode, the GDSC will be enabled
         * again, hence we need to poll for GDSC to complete the power up.
         */
        if (!mode)
                return gdsc_poll_status(sc, GDSC_ON);

        return 0;
}

static bool gdsc_get_hwmode(struct generic_pm_domain *domain, struct device *dev)
{
        struct gdsc *sc = domain_to_gdsc(domain);
        u32 val;

        regmap_read(sc->regmap, sc->gdscr, &val);

        return !!(val & HW_CONTROL_MASK);
}

static int gdsc_init(struct gdsc *sc)
{
        u32 mask, val;
        int on, ret;

        /*
         * Disable HW trigger: collapse/restore occur based on registers writes.
         * Disable SW override: Use hardware state-machine for sequencing.
         * Configure wait time between states.
         */
        mask = HW_CONTROL_MASK | SW_OVERRIDE_MASK |
               EN_REST_WAIT_MASK | EN_FEW_WAIT_MASK | CLK_DIS_WAIT_MASK;

        if (!sc->en_rest_wait_val)
                sc->en_rest_wait_val = EN_REST_WAIT_VAL;
        if (!sc->en_few_wait_val)
                sc->en_few_wait_val = EN_FEW_WAIT_VAL;
        if (!sc->clk_dis_wait_val)
                sc->clk_dis_wait_val = CLK_DIS_WAIT_VAL;

        val = sc->en_rest_wait_val << EN_REST_WAIT_SHIFT |
                sc->en_few_wait_val << EN_FEW_WAIT_SHIFT |
                sc->clk_dis_wait_val << CLK_DIS_WAIT_SHIFT;

        ret = regmap_update_bits(sc->regmap, sc->gdscr, mask, val);
        if (ret)
                return ret;

        /* Force gdsc ON if only ON state is supported */
        if (sc->pwrsts == PWRSTS_ON) {
                ret = gdsc_toggle_logic(sc, GDSC_ON, false);
                if (ret)
                        return ret;
        }

        on = gdsc_check_status(sc, GDSC_ON);
        if (on < 0)
                return on;

        if (on) {
                /* The regulator must be on, sync the kernel state */
                if (sc->rsupply) {
                        ret = regulator_enable(sc->rsupply);
                        if (ret < 0)
                                return ret;
                }

                /*
                 * Votable GDSCs can be ON due to Vote from other masters.
                 * If a Votable GDSC is ON, make sure we have a Vote.
                 */
                if (sc->flags & VOTABLE) {
                        ret = gdsc_update_collapse_bit(sc, false);
                        if (ret)
                                goto err_disable_supply;
                }

                /*
                 * Make sure the retain bit is set if the GDSC is already on,
                 * otherwise we end up turning off the GDSC and destroying all
                 * the register contents that we thought we were saving.
                 */
                if (sc->flags & RETAIN_FF_ENABLE)
                        gdsc_retain_ff_on(sc);

                /* Turn on HW trigger mode if supported */
                if (sc->flags & HW_CTRL) {
                        ret = gdsc_hwctrl(sc, true);
                        if (ret < 0)
                                goto err_disable_supply;
                }

        } else if (sc->flags & ALWAYS_ON) {
                /* If ALWAYS_ON GDSCs are not ON, turn them ON */
                gdsc_enable(&sc->pd);
                on = true;
        }

        if (on || (sc->pwrsts & PWRSTS_RET))
                gdsc_force_mem_on(sc);
        else
                gdsc_clear_mem_on(sc);

        if (sc->flags & ALWAYS_ON)
                sc->pd.flags |= GENPD_FLAG_ALWAYS_ON;
        if (!sc->pd.power_off)
                sc->pd.power_off = gdsc_disable;
        if (!sc->pd.power_on)
                sc->pd.power_on = gdsc_enable;
        if (sc->flags & HW_CTRL_TRIGGER) {
                sc->pd.set_hwmode_dev = gdsc_set_hwmode;
                sc->pd.get_hwmode_dev = gdsc_get_hwmode;
        }

        ret = pm_genpd_init(&sc->pd, NULL, !on);
        if (ret)
                goto err_disable_supply;

        return 0;

err_disable_supply:
        if (on && sc->rsupply)
                regulator_disable(sc->rsupply);

        return ret;
}

static int gdsc_add_subdomain_list(struct dev_pm_domain_list *pd_list,
                                   struct generic_pm_domain *subdomain)
{
        int i, ret;

        for (i = 0; i < pd_list->num_pds; i++) {
                struct device *dev = pd_list->pd_devs[i];
                struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain);

                ret = pm_genpd_add_subdomain(genpd, subdomain);
                if (ret)
                        return ret;
        }

        return 0;
}

static void gdsc_remove_subdomain_list(struct dev_pm_domain_list *pd_list,
                                       struct generic_pm_domain *subdomain)
{
        int i;

        for (i = 0; i < pd_list->num_pds; i++) {
                struct device *dev = pd_list->pd_devs[i];
                struct generic_pm_domain *genpd = pd_to_genpd(dev->pm_domain);

                pm_genpd_remove_subdomain(genpd, subdomain);
        }
}

static void gdsc_pm_subdomain_remove(struct gdsc_desc *desc, size_t num)
{
        struct device *dev = desc->dev;
        struct gdsc **scs = desc->scs;
        int i;

        /* Remove subdomains */
        for (i = num - 1; i >= 0; i--) {
                if (!scs[i])
                        continue;
                if (scs[i]->parent)
                        pm_genpd_remove_subdomain(scs[i]->parent, &scs[i]->pd);
                else if (!IS_ERR_OR_NULL(dev->pm_domain))
                        pm_genpd_remove_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
                else if (desc->pd_list)
                        gdsc_remove_subdomain_list(desc->pd_list, &scs[i]->pd);
        }
}

int gdsc_register(struct gdsc_desc *desc,
                  struct reset_controller_dev *rcdev, struct regmap *regmap)
{
        int i, ret;
        struct genpd_onecell_data *data;
        struct device *dev = desc->dev;
        struct gdsc **scs = desc->scs;
        size_t num = desc->num;

        data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
        if (!data)
                return -ENOMEM;

        data->domains = devm_kcalloc(dev, num, sizeof(*data->domains),
                                     GFP_KERNEL);
        if (!data->domains)
                return -ENOMEM;

        for (i = 0; i < num; i++) {
                if (!scs[i] || !scs[i]->supply)
                        continue;

                scs[i]->rsupply = devm_regulator_get_optional(dev, scs[i]->supply);
                if (IS_ERR(scs[i]->rsupply)) {
                        ret = PTR_ERR(scs[i]->rsupply);
                        if (ret != -ENODEV)
                                return ret;

                        scs[i]->rsupply = NULL;
                }
        }

        data->num_domains = num;
        for (i = 0; i < num; i++) {
                if (!scs[i])
                        continue;
                scs[i]->regmap = regmap;
                scs[i]->rcdev = rcdev;
                ret = gdsc_init(scs[i]);
                if (ret)
                        return ret;
                data->domains[i] = &scs[i]->pd;
        }

        /* Add subdomains */
        for (i = 0; i < num; i++) {
                if (!scs[i])
                        continue;
                if (scs[i]->parent)
                        ret = pm_genpd_add_subdomain(scs[i]->parent, &scs[i]->pd);
                else if (!IS_ERR_OR_NULL(dev->pm_domain))
                        ret = pm_genpd_add_subdomain(pd_to_genpd(dev->pm_domain), &scs[i]->pd);
                else if (desc->pd_list)
                        ret = gdsc_add_subdomain_list(desc->pd_list, &scs[i]->pd);

                if (ret)
                        goto err_pm_subdomain_remove;
        }

        return of_genpd_add_provider_onecell(dev->of_node, data);

err_pm_subdomain_remove:
        gdsc_pm_subdomain_remove(desc, i);

        return ret;
}

void gdsc_unregister(struct gdsc_desc *desc)
{
        struct device *dev = desc->dev;
        size_t num = desc->num;

        gdsc_pm_subdomain_remove(desc, num);
        of_genpd_del_provider(dev->of_node);
}

/*
 * On SDM845+ the GPU GX domain is *almost* entirely controlled by the GMU
 * running in the CX domain so the CPU doesn't need to know anything about the
 * GX domain EXCEPT....
 *
 * Hardware constraints dictate that the GX be powered down before the CX. If
 * the GMU crashes it could leave the GX on. In order to successfully bring back
 * the device the CPU needs to disable the GX headswitch. There being no sane
 * way to reach in and touch that register from deep inside the GPU driver we
 * need to set up the infrastructure to be able to ensure that the GPU can
 * ensure that the GX is off during this super special case. We do this by
 * defining a GX gdsc with a dummy enable function and a "default" disable
 * function.
 *
 * This allows us to attach with genpd_dev_pm_attach_by_name() in the GPU
 * driver. During power up, nothing will happen from the CPU (and the GMU will
 * power up normally but during power down this will ensure that the GX domain
 * is *really* off - this gives us a semi standard way of doing what we need.
 */
int gdsc_gx_do_nothing_enable(struct generic_pm_domain *domain)
{
        struct gdsc *sc = domain_to_gdsc(domain);
        int ret = 0;

        /* Enable the parent supply, when controlled through the regulator framework. */
        if (sc->rsupply)
                ret = regulator_enable(sc->rsupply);

        /* Do nothing with the GDSC itself */

        return ret;
}
EXPORT_SYMBOL_GPL(gdsc_gx_do_nothing_enable);