// SPDX-License-Identifier: GPL-2.0
/*
 * JZ47xx SoCs TCU clocks driver
 * Copyright (C) 2019 Paul Cercueil <paul@crapouillou.net>
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/clockchips.h>
#include <linux/mfd/ingenic-tcu.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <linux/syscore_ops.h>

#include <dt-bindings/clock/ingenic,tcu.h>

/* 8 channels max + watchdog + OST */
#define TCU_CLK_COUNT   10

#undef pr_fmt
#define pr_fmt(fmt) "ingenic-tcu-clk: " fmt

enum tcu_clk_parent {
        TCU_PARENT_PCLK,
        TCU_PARENT_RTC,
        TCU_PARENT_EXT,
};

struct ingenic_soc_info {
        unsigned int num_channels;
        bool has_ost;
        bool has_tcu_clk;
        bool allow_missing_tcu_clk;
};

struct ingenic_tcu_clk_info {
        struct clk_init_data init_data;
        u8 gate_bit;
        u8 tcsr_reg;
};

struct ingenic_tcu_clk {
        struct clk_hw hw;
        unsigned int idx;
        struct ingenic_tcu *tcu;
        const struct ingenic_tcu_clk_info *info;
};

struct ingenic_tcu {
        const struct ingenic_soc_info *soc_info;
        struct regmap *map;
        struct clk *clk;

        struct clk_hw_onecell_data *clocks;
};

static struct ingenic_tcu *ingenic_tcu;

static inline struct ingenic_tcu_clk *to_tcu_clk(struct clk_hw *hw)
{
        return container_of(hw, struct ingenic_tcu_clk, hw);
}

static int ingenic_tcu_enable(struct clk_hw *hw)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        struct ingenic_tcu *tcu = tcu_clk->tcu;

        regmap_write(tcu->map, TCU_REG_TSCR, BIT(info->gate_bit));

        return 0;
}

static void ingenic_tcu_disable(struct clk_hw *hw)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        struct ingenic_tcu *tcu = tcu_clk->tcu;

        regmap_write(tcu->map, TCU_REG_TSSR, BIT(info->gate_bit));
}

static int ingenic_tcu_is_enabled(struct clk_hw *hw)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        unsigned int value;

        regmap_read(tcu_clk->tcu->map, TCU_REG_TSR, &value);

        return !(value & BIT(info->gate_bit));
}

static bool ingenic_tcu_enable_regs(struct clk_hw *hw)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        struct ingenic_tcu *tcu = tcu_clk->tcu;
        bool enabled = false;

        /*
         * According to the programming manual, a timer channel's registers can
         * only be accessed when the channel's stop bit is clear.
         */
        enabled = !!ingenic_tcu_is_enabled(hw);
        regmap_write(tcu->map, TCU_REG_TSCR, BIT(info->gate_bit));

        return enabled;
}

static void ingenic_tcu_disable_regs(struct clk_hw *hw)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        struct ingenic_tcu *tcu = tcu_clk->tcu;

        regmap_write(tcu->map, TCU_REG_TSSR, BIT(info->gate_bit));
}

static u8 ingenic_tcu_get_parent(struct clk_hw *hw)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        unsigned int val = 0;
        int ret;

        ret = regmap_read(tcu_clk->tcu->map, info->tcsr_reg, &val);
        WARN_ONCE(ret < 0, "Unable to read TCSR %d", tcu_clk->idx);

        return ffs(val & TCU_TCSR_PARENT_CLOCK_MASK) - 1;
}

static int ingenic_tcu_set_parent(struct clk_hw *hw, u8 idx)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        bool was_enabled;
        int ret;

        was_enabled = ingenic_tcu_enable_regs(hw);

        ret = regmap_update_bits(tcu_clk->tcu->map, info->tcsr_reg,
                                 TCU_TCSR_PARENT_CLOCK_MASK, BIT(idx));
        WARN_ONCE(ret < 0, "Unable to update TCSR %d", tcu_clk->idx);

        if (!was_enabled)
                ingenic_tcu_disable_regs(hw);

        return 0;
}

static unsigned long ingenic_tcu_recalc_rate(struct clk_hw *hw,
                unsigned long parent_rate)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        unsigned int prescale;
        int ret;

        ret = regmap_read(tcu_clk->tcu->map, info->tcsr_reg, &prescale);
        WARN_ONCE(ret < 0, "Unable to read TCSR %d", tcu_clk->idx);

        prescale = (prescale & TCU_TCSR_PRESCALE_MASK) >> TCU_TCSR_PRESCALE_LSB;

        return parent_rate >> (prescale * 2);
}

static u8 ingenic_tcu_get_prescale(unsigned long rate, unsigned long req_rate)
{
        u8 prescale;

        for (prescale = 0; prescale < 5; prescale++)
                if ((rate >> (prescale * 2)) <= req_rate)
                        return prescale;

        return 5; /* /1024 divider */
}

static int ingenic_tcu_determine_rate(struct clk_hw *hw,
                                      struct clk_rate_request *req)
{
        unsigned long rate = req->best_parent_rate;
        u8 prescale;

        if (req->rate > rate) {
                req->rate = rate;
                return 0;
        }

        prescale = ingenic_tcu_get_prescale(rate, req->rate);

        req->rate = rate >> (prescale * 2);
        return 0;
}

static int ingenic_tcu_set_rate(struct clk_hw *hw, unsigned long req_rate,
                unsigned long parent_rate)
{
        struct ingenic_tcu_clk *tcu_clk = to_tcu_clk(hw);
        const struct ingenic_tcu_clk_info *info = tcu_clk->info;
        u8 prescale = ingenic_tcu_get_prescale(parent_rate, req_rate);
        bool was_enabled;
        int ret;

        was_enabled = ingenic_tcu_enable_regs(hw);

        ret = regmap_update_bits(tcu_clk->tcu->map, info->tcsr_reg,
                                 TCU_TCSR_PRESCALE_MASK,
                                 prescale << TCU_TCSR_PRESCALE_LSB);
        WARN_ONCE(ret < 0, "Unable to update TCSR %d", tcu_clk->idx);

        if (!was_enabled)
                ingenic_tcu_disable_regs(hw);

        return 0;
}

static const struct clk_ops ingenic_tcu_clk_ops = {
        .get_parent     = ingenic_tcu_get_parent,
        .set_parent     = ingenic_tcu_set_parent,

        .recalc_rate    = ingenic_tcu_recalc_rate,
        .determine_rate = ingenic_tcu_determine_rate,
        .set_rate       = ingenic_tcu_set_rate,

        .enable         = ingenic_tcu_enable,
        .disable        = ingenic_tcu_disable,
        .is_enabled     = ingenic_tcu_is_enabled,
};

static const char * const ingenic_tcu_timer_parents[] = {
        [TCU_PARENT_PCLK] = "pclk",
        [TCU_PARENT_RTC]  = "rtc",
        [TCU_PARENT_EXT]  = "ext",
};

#define DEF_TIMER(_name, _gate_bit, _tcsr)                              \
        {                                                               \
                .init_data = {                                          \
                        .name = _name,                                  \
                        .parent_names = ingenic_tcu_timer_parents,      \
                        .num_parents = ARRAY_SIZE(ingenic_tcu_timer_parents),\
                        .ops = &ingenic_tcu_clk_ops,                    \
                        .flags = CLK_SET_RATE_UNGATE,                   \
                },                                                      \
                .gate_bit = _gate_bit,                                  \
                .tcsr_reg = _tcsr,                                      \
        }
static const struct ingenic_tcu_clk_info ingenic_tcu_clk_info[] = {
        [TCU_CLK_TIMER0] = DEF_TIMER("timer0", 0, TCU_REG_TCSRc(0)),
        [TCU_CLK_TIMER1] = DEF_TIMER("timer1", 1, TCU_REG_TCSRc(1)),
        [TCU_CLK_TIMER2] = DEF_TIMER("timer2", 2, TCU_REG_TCSRc(2)),
        [TCU_CLK_TIMER3] = DEF_TIMER("timer3", 3, TCU_REG_TCSRc(3)),
        [TCU_CLK_TIMER4] = DEF_TIMER("timer4", 4, TCU_REG_TCSRc(4)),
        [TCU_CLK_TIMER5] = DEF_TIMER("timer5", 5, TCU_REG_TCSRc(5)),
        [TCU_CLK_TIMER6] = DEF_TIMER("timer6", 6, TCU_REG_TCSRc(6)),
        [TCU_CLK_TIMER7] = DEF_TIMER("timer7", 7, TCU_REG_TCSRc(7)),
};

static const struct ingenic_tcu_clk_info ingenic_tcu_watchdog_clk_info =
                                         DEF_TIMER("wdt", 16, TCU_REG_WDT_TCSR);
static const struct ingenic_tcu_clk_info ingenic_tcu_ost_clk_info =
                                         DEF_TIMER("ost", 15, TCU_REG_OST_TCSR);
#undef DEF_TIMER

static int __init ingenic_tcu_register_clock(struct ingenic_tcu *tcu,
                        unsigned int idx, enum tcu_clk_parent parent,
                        const struct ingenic_tcu_clk_info *info,
                        struct clk_hw_onecell_data *clocks)
{
        struct ingenic_tcu_clk *tcu_clk;
        int err;

        tcu_clk = kzalloc_obj(*tcu_clk);
        if (!tcu_clk)
                return -ENOMEM;

        tcu_clk->hw.init = &info->init_data;
        tcu_clk->idx = idx;
        tcu_clk->info = info;
        tcu_clk->tcu = tcu;

        /* Reset channel and clock divider, set default parent */
        ingenic_tcu_enable_regs(&tcu_clk->hw);
        regmap_update_bits(tcu->map, info->tcsr_reg, 0xffff, BIT(parent));
        ingenic_tcu_disable_regs(&tcu_clk->hw);

        err = clk_hw_register(NULL, &tcu_clk->hw);
        if (err) {
                kfree(tcu_clk);
                return err;
        }

        clocks->hws[idx] = &tcu_clk->hw;

        return 0;
}

static const struct ingenic_soc_info jz4740_soc_info = {
        .num_channels = 8,
        .has_ost = false,
        .has_tcu_clk = true,
};

static const struct ingenic_soc_info jz4725b_soc_info = {
        .num_channels = 6,
        .has_ost = true,
        .has_tcu_clk = true,
};

static const struct ingenic_soc_info jz4770_soc_info = {
        .num_channels = 8,
        .has_ost = true,
        .has_tcu_clk = false,
};

static const struct ingenic_soc_info x1000_soc_info = {
        .num_channels = 8,
        .has_ost = false, /* X1000 has OST, but it not belong TCU */
        .has_tcu_clk = true,
        .allow_missing_tcu_clk = true,
};

static const struct of_device_id __maybe_unused ingenic_tcu_of_match[] __initconst = {
        { .compatible = "ingenic,jz4740-tcu", .data = &jz4740_soc_info, },
        { .compatible = "ingenic,jz4725b-tcu", .data = &jz4725b_soc_info, },
        { .compatible = "ingenic,jz4760-tcu", .data = &jz4770_soc_info, },
        { .compatible = "ingenic,jz4770-tcu", .data = &jz4770_soc_info, },
        { .compatible = "ingenic,x1000-tcu", .data = &x1000_soc_info, },
        { /* sentinel */ }
};

static int __init ingenic_tcu_probe(struct device_node *np)
{
        const struct of_device_id *id = of_match_node(ingenic_tcu_of_match, np);
        struct ingenic_tcu *tcu;
        struct regmap *map;
        unsigned int i;
        int ret;

        map = device_node_to_regmap(np);
        if (IS_ERR(map))
                return PTR_ERR(map);

        tcu = kzalloc_obj(*tcu);
        if (!tcu)
                return -ENOMEM;

        tcu->map = map;
        tcu->soc_info = id->data;

        if (tcu->soc_info->has_tcu_clk) {
                tcu->clk = of_clk_get_by_name(np, "tcu");
                if (IS_ERR(tcu->clk)) {
                        ret = PTR_ERR(tcu->clk);

                        /*
                         * Old device trees for some SoCs did not include the
                         * TCU clock because this driver (incorrectly) didn't
                         * use it. In this case we complain loudly and attempt
                         * to continue without the clock, which might work if
                         * booting with workarounds like "clk_ignore_unused".
                         */
                        if (tcu->soc_info->allow_missing_tcu_clk && ret == -EINVAL) {
                                pr_warn("TCU clock missing from device tree, please update your device tree\n");
                                tcu->clk = NULL;
                        } else {
                                pr_crit("Cannot get TCU clock from device tree\n");
                                goto err_free_tcu;
                        }
                } else {
                        ret = clk_prepare_enable(tcu->clk);
                        if (ret) {
                                pr_crit("Unable to enable TCU clock\n");
                                goto err_put_clk;
                        }
                }
        }

        tcu->clocks = kzalloc_flex(*tcu->clocks, hws, TCU_CLK_COUNT);
        if (!tcu->clocks) {
                ret = -ENOMEM;
                goto err_clk_disable;
        }

        tcu->clocks->num = TCU_CLK_COUNT;

        for (i = 0; i < tcu->soc_info->num_channels; i++) {
                ret = ingenic_tcu_register_clock(tcu, i, TCU_PARENT_EXT,
                                                 &ingenic_tcu_clk_info[i],
                                                 tcu->clocks);
                if (ret) {
                        pr_crit("cannot register clock %d\n", i);
                        goto err_unregister_timer_clocks;
                }
        }

        /*
         * We set EXT as the default parent clock for all the TCU clocks
         * except for the watchdog one, where we set the RTC clock as the
         * parent. Since the EXT and PCLK are much faster than the RTC clock,
         * the watchdog would kick after a maximum time of 5s, and we might
         * want a slower kicking time.
         */
        ret = ingenic_tcu_register_clock(tcu, TCU_CLK_WDT, TCU_PARENT_RTC,
                                         &ingenic_tcu_watchdog_clk_info,
                                         tcu->clocks);
        if (ret) {
                pr_crit("cannot register watchdog clock\n");
                goto err_unregister_timer_clocks;
        }

        if (tcu->soc_info->has_ost) {
                ret = ingenic_tcu_register_clock(tcu, TCU_CLK_OST,
                                                 TCU_PARENT_EXT,
                                                 &ingenic_tcu_ost_clk_info,
                                                 tcu->clocks);
                if (ret) {
                        pr_crit("cannot register ost clock\n");
                        goto err_unregister_watchdog_clock;
                }
        }

        ret = of_clk_add_hw_provider(np, of_clk_hw_onecell_get, tcu->clocks);
        if (ret) {
                pr_crit("cannot add OF clock provider\n");
                goto err_unregister_ost_clock;
        }

        ingenic_tcu = tcu;

        return 0;

err_unregister_ost_clock:
        if (tcu->soc_info->has_ost)
                clk_hw_unregister(tcu->clocks->hws[i + 1]);
err_unregister_watchdog_clock:
        clk_hw_unregister(tcu->clocks->hws[i]);
err_unregister_timer_clocks:
        for (i = 0; i < tcu->clocks->num; i++)
                if (tcu->clocks->hws[i])
                        clk_hw_unregister(tcu->clocks->hws[i]);
        kfree(tcu->clocks);
err_clk_disable:
        if (tcu->clk)
                clk_disable_unprepare(tcu->clk);
err_put_clk:
        if (tcu->clk)
                clk_put(tcu->clk);
err_free_tcu:
        kfree(tcu);
        return ret;
}

static int __maybe_unused tcu_pm_suspend(void *data)
{
        struct ingenic_tcu *tcu = ingenic_tcu;

        if (tcu->clk)
                clk_disable(tcu->clk);

        return 0;
}

static void __maybe_unused tcu_pm_resume(void *data)
{
        struct ingenic_tcu *tcu = ingenic_tcu;

        if (tcu->clk)
                clk_enable(tcu->clk);
}

static const struct syscore_ops __maybe_unused tcu_pm_ops = {
        .suspend = tcu_pm_suspend,
        .resume = tcu_pm_resume,
};

static struct syscore __maybe_unused tcu_pm = {
        .ops = &tcu_pm_ops,
};

static void __init ingenic_tcu_init(struct device_node *np)
{
        int ret = ingenic_tcu_probe(np);

        if (ret)
                pr_crit("Failed to initialize TCU clocks: %d\n", ret);

        if (IS_ENABLED(CONFIG_PM_SLEEP))
                register_syscore(&tcu_pm);
}

CLK_OF_DECLARE_DRIVER(jz4740_cgu, "ingenic,jz4740-tcu", ingenic_tcu_init);
CLK_OF_DECLARE_DRIVER(jz4725b_cgu, "ingenic,jz4725b-tcu", ingenic_tcu_init);
CLK_OF_DECLARE_DRIVER(jz4760_cgu, "ingenic,jz4760-tcu", ingenic_tcu_init);
CLK_OF_DECLARE_DRIVER(jz4770_cgu, "ingenic,jz4770-tcu", ingenic_tcu_init);
CLK_OF_DECLARE_DRIVER(x1000_cgu, "ingenic,x1000-tcu", ingenic_tcu_init);