/*
 * OMAP clkctrl clock support
 *
 * Copyright (C) 2017 Texas Instruments, Inc.
 *
 * Tero Kristo <t-kristo@ti.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 * This program is distributed "as is" WITHOUT ANY WARRANTY of any
 * kind, whether express or implied; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

#include <linux/clk-provider.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/clk/ti.h>
#include <linux/delay.h>
#include <linux/timekeeping.h>
#include "clock.h"

#define NO_IDLEST                       0

#define OMAP4_MODULEMODE_MASK           0x3

#define MODULEMODE_HWCTRL               0x1
#define MODULEMODE_SWCTRL               0x2

#define OMAP4_IDLEST_MASK               (0x3 << 16)
#define OMAP4_IDLEST_SHIFT              16

#define OMAP4_STBYST_MASK               BIT(18)
#define OMAP4_STBYST_SHIFT              18

#define CLKCTRL_IDLEST_FUNCTIONAL       0x0
#define CLKCTRL_IDLEST_INTERFACE_IDLE   0x2
#define CLKCTRL_IDLEST_DISABLED         0x3

/* These timeouts are in us */
#define OMAP4_MAX_MODULE_READY_TIME     2000
#define OMAP4_MAX_MODULE_DISABLE_TIME   5000

static bool _early_timeout = true;

struct omap_clkctrl_provider {
        void __iomem *base;
        struct list_head clocks;
        char *clkdm_name;
};

struct omap_clkctrl_clk {
        struct clk_hw *clk;
        u16 reg_offset;
        int bit_offset;
        struct list_head node;
};

union omap4_timeout {
        u32 cycles;
        ktime_t start;
};

static const struct omap_clkctrl_data default_clkctrl_data[] __initconst = {
        { 0 },
};

static u32 _omap4_idlest(u32 val)
{
        val &= OMAP4_IDLEST_MASK;
        val >>= OMAP4_IDLEST_SHIFT;

        return val;
}

static bool _omap4_is_idle(u32 val)
{
        val = _omap4_idlest(val);

        return val == CLKCTRL_IDLEST_DISABLED;
}

static bool _omap4_is_ready(u32 val)
{
        val = _omap4_idlest(val);

        return val == CLKCTRL_IDLEST_FUNCTIONAL ||
               val == CLKCTRL_IDLEST_INTERFACE_IDLE;
}

static bool _omap4_is_timeout(union omap4_timeout *time, u32 timeout)
{
        /*
         * There are two special cases where ktime_to_ns() can't be
         * used to track the timeouts. First one is during early boot
         * when the timers haven't been initialized yet. The second
         * one is during suspend-resume cycle while timekeeping is
         * being suspended / resumed. Clocksource for the system
         * can be from a timer that requires pm_runtime access, which
         * will eventually bring us here with timekeeping_suspended,
         * during both suspend entry and resume paths. This happens
         * at least on am43xx platform. Account for flakeyness
         * with udelay() by multiplying the timeout value by 2.
         */
        if (unlikely(_early_timeout || timekeeping_suspended)) {
                if (time->cycles++ < timeout) {
                        udelay(1 * 2);
                        return false;
                }
        } else {
                if (!ktime_to_ns(time->start)) {
                        time->start = ktime_get();
                        return false;
                }

                if (ktime_us_delta(ktime_get(), time->start) < timeout) {
                        cpu_relax();
                        return false;
                }
        }

        return true;
}

static int __init _omap4_disable_early_timeout(void)
{
        _early_timeout = false;

        return 0;
}
arch_initcall(_omap4_disable_early_timeout);

static int _omap4_clkctrl_clk_enable(struct clk_hw *hw)
{
        struct clk_hw_omap *clk = to_clk_hw_omap(hw);
        u32 val;
        int ret;
        union omap4_timeout timeout = { 0 };

        if (clk->clkdm) {
                ret = ti_clk_ll_ops->clkdm_clk_enable(clk->clkdm, hw->clk);
                if (ret) {
                        WARN(1,
                             "%s: could not enable %s's clockdomain %s: %d\n",
                             __func__, clk_hw_get_name(hw),
                             clk->clkdm_name, ret);
                        return ret;
                }
        }

        if (!clk->enable_bit)
                return 0;

        val = ti_clk_ll_ops->clk_readl(&clk->enable_reg);

        val &= ~OMAP4_MODULEMODE_MASK;
        val |= clk->enable_bit;

        ti_clk_ll_ops->clk_writel(val, &clk->enable_reg);

        if (test_bit(NO_IDLEST, &clk->flags))
                return 0;

        /* Wait until module is enabled */
        while (!_omap4_is_ready(ti_clk_ll_ops->clk_readl(&clk->enable_reg))) {
                if (_omap4_is_timeout(&timeout, OMAP4_MAX_MODULE_READY_TIME)) {
                        pr_err("%s: failed to enable\n", clk_hw_get_name(hw));
                        return -EBUSY;
                }
        }

        return 0;
}

static void _omap4_clkctrl_clk_disable(struct clk_hw *hw)
{
        struct clk_hw_omap *clk = to_clk_hw_omap(hw);
        u32 val;
        union omap4_timeout timeout = { 0 };

        if (!clk->enable_bit)
                goto exit;

        val = ti_clk_ll_ops->clk_readl(&clk->enable_reg);

        val &= ~OMAP4_MODULEMODE_MASK;

        ti_clk_ll_ops->clk_writel(val, &clk->enable_reg);

        if (test_bit(NO_IDLEST, &clk->flags))
                goto exit;

        /* Wait until module is disabled */
        while (!_omap4_is_idle(ti_clk_ll_ops->clk_readl(&clk->enable_reg))) {
                if (_omap4_is_timeout(&timeout,
                                      OMAP4_MAX_MODULE_DISABLE_TIME)) {
                        pr_err("%s: failed to disable\n", clk_hw_get_name(hw));
                        break;
                }
        }

exit:
        if (clk->clkdm)
                ti_clk_ll_ops->clkdm_clk_disable(clk->clkdm, hw->clk);
}

static int _omap4_clkctrl_clk_is_enabled(struct clk_hw *hw)
{
        struct clk_hw_omap *clk = to_clk_hw_omap(hw);
        u32 val;

        val = ti_clk_ll_ops->clk_readl(&clk->enable_reg);

        if (val & clk->enable_bit)
                return 1;

        return 0;
}

static const struct clk_ops omap4_clkctrl_clk_ops = {
        .enable         = _omap4_clkctrl_clk_enable,
        .disable        = _omap4_clkctrl_clk_disable,
        .is_enabled     = _omap4_clkctrl_clk_is_enabled,
        .init           = omap2_init_clk_clkdm,
};

static struct clk_hw *_ti_omap4_clkctrl_xlate(struct of_phandle_args *clkspec,
                                              void *data)
{
        struct omap_clkctrl_provider *provider = data;
        struct omap_clkctrl_clk *entry;
        bool found = false;

        if (clkspec->args_count != 2)
                return ERR_PTR(-EINVAL);

        pr_debug("%s: looking for %x:%x\n", __func__,
                 clkspec->args[0], clkspec->args[1]);

        list_for_each_entry(entry, &provider->clocks, node) {
                if (entry->reg_offset == clkspec->args[0] &&
                    entry->bit_offset == clkspec->args[1]) {
                        found = true;
                        break;
                }
        }

        if (!found)
                return ERR_PTR(-EINVAL);

        return entry->clk;
}

/* Get clkctrl clock base name based on clkctrl_name or dts node */
static const char * __init clkctrl_get_clock_name(struct device_node *np,
                                                  const char *clkctrl_name,
                                                  int offset, int index,
                                                  bool legacy_naming)
{
        char *clock_name;

        /* l4per-clkctrl:1234:0 style naming based on clkctrl_name */
        if (clkctrl_name && !legacy_naming) {
                clock_name = kasprintf(GFP_KERNEL, "%s-clkctrl:%04x:%d",
                                       clkctrl_name, offset, index);
                strreplace(clock_name, '_', '-');

                return clock_name;
        }

        /* l4per:1234:0 old style naming based on clkctrl_name */
        if (clkctrl_name)
                return kasprintf(GFP_KERNEL, "%s_cm:clk:%04x:%d",
                                 clkctrl_name, offset, index);

        /* l4per_cm:1234:0 old style naming based on parent node name */
        if (legacy_naming)
                return kasprintf(GFP_KERNEL, "%pOFn:clk:%04x:%d",
                                 np->parent, offset, index);

        /* l4per-clkctrl:1234:0 style naming based on node name */
        return kasprintf(GFP_KERNEL, "%pOFn:%04x:%d", np, offset, index);
}

static int __init
_ti_clkctrl_clk_register(struct omap_clkctrl_provider *provider,
                         struct device_node *node, struct clk_hw *clk_hw,
                         u16 offset, u8 bit, const char * const *parents,
                         int num_parents, const struct clk_ops *ops,
                         const char *clkctrl_name)
{
        struct clk_init_data init = { NULL };
        struct clk *clk;
        struct omap_clkctrl_clk *clkctrl_clk;
        int ret = 0;

        init.name = clkctrl_get_clock_name(node, clkctrl_name, offset, bit,
                                           ti_clk_get_features()->flags &
                                           TI_CLK_CLKCTRL_COMPAT);

        clkctrl_clk = kzalloc(sizeof(*clkctrl_clk), GFP_KERNEL);
        if (!init.name || !clkctrl_clk) {
                ret = -ENOMEM;
                goto cleanup;
        }

        clk_hw->init = &init;
        init.parent_names = parents;
        init.num_parents = num_parents;
        init.ops = ops;
        init.flags = 0;

        clk = ti_clk_register(NULL, clk_hw, init.name);
        if (IS_ERR_OR_NULL(clk)) {
                ret = -EINVAL;
                goto cleanup;
        }

        clkctrl_clk->reg_offset = offset;
        clkctrl_clk->bit_offset = bit;
        clkctrl_clk->clk = clk_hw;

        list_add(&clkctrl_clk->node, &provider->clocks);

        return 0;

cleanup:
        kfree(init.name);
        kfree(clkctrl_clk);
        return ret;
}

static void __init
_ti_clkctrl_setup_gate(struct omap_clkctrl_provider *provider,
                       struct device_node *node, u16 offset,
                       const struct omap_clkctrl_bit_data *data,
                       void __iomem *reg, const char *clkctrl_name)
{
        struct clk_hw_omap *clk_hw;

        clk_hw = kzalloc(sizeof(*clk_hw), GFP_KERNEL);
        if (!clk_hw)
                return;

        clk_hw->enable_bit = data->bit;
        clk_hw->enable_reg.ptr = reg;

        if (_ti_clkctrl_clk_register(provider, node, &clk_hw->hw, offset,
                                     data->bit, data->parents, 1,
                                     &omap_gate_clk_ops, clkctrl_name))
                kfree(clk_hw);
}

static void __init
_ti_clkctrl_setup_mux(struct omap_clkctrl_provider *provider,
                      struct device_node *node, u16 offset,
                      const struct omap_clkctrl_bit_data *data,
                      void __iomem *reg, const char *clkctrl_name)
{
        struct clk_omap_mux *mux;
        int num_parents = 0;
        const char * const *pname;

        mux = kzalloc(sizeof(*mux), GFP_KERNEL);
        if (!mux)
                return;

        pname = data->parents;
        while (*pname) {
                num_parents++;
                pname++;
        }

        mux->mask = num_parents;
        if (!(mux->flags & CLK_MUX_INDEX_ONE))
                mux->mask--;

        mux->mask = (1 << fls(mux->mask)) - 1;

        mux->shift = data->bit;
        mux->reg.ptr = reg;

        if (_ti_clkctrl_clk_register(provider, node, &mux->hw, offset,
                                     data->bit, data->parents, num_parents,
                                     &ti_clk_mux_ops, clkctrl_name))
                kfree(mux);
}

static void __init
_ti_clkctrl_setup_div(struct omap_clkctrl_provider *provider,
                      struct device_node *node, u16 offset,
                      const struct omap_clkctrl_bit_data *data,
                      void __iomem *reg, const char *clkctrl_name)
{
        struct clk_omap_divider *div;
        const struct omap_clkctrl_div_data *div_data = data->data;
        u8 div_flags = 0;

        div = kzalloc(sizeof(*div), GFP_KERNEL);
        if (!div)
                return;

        div->reg.ptr = reg;
        div->shift = data->bit;
        div->flags = div_data->flags;

        if (div->flags & CLK_DIVIDER_POWER_OF_TWO)
                div_flags |= CLKF_INDEX_POWER_OF_TWO;

        if (ti_clk_parse_divider_data((int *)div_data->dividers, 0,
                                      div_data->max_div, div_flags,
                                      div)) {
                pr_err("%s: Data parsing for %pOF:%04x:%d failed\n", __func__,
                       node, offset, data->bit);
                kfree(div);
                return;
        }

        if (_ti_clkctrl_clk_register(provider, node, &div->hw, offset,
                                     data->bit, data->parents, 1,
                                     &ti_clk_divider_ops, clkctrl_name))
                kfree(div);
}

static void __init
_ti_clkctrl_setup_subclks(struct omap_clkctrl_provider *provider,
                          struct device_node *node,
                          const struct omap_clkctrl_reg_data *data,
                          void __iomem *reg, const char *clkctrl_name)
{
        const struct omap_clkctrl_bit_data *bits = data->bit_data;

        if (!bits)
                return;

        while (bits->bit) {
                switch (bits->type) {
                case TI_CLK_GATE:
                        _ti_clkctrl_setup_gate(provider, node, data->offset,
                                               bits, reg, clkctrl_name);
                        break;

                case TI_CLK_DIVIDER:
                        _ti_clkctrl_setup_div(provider, node, data->offset,
                                              bits, reg, clkctrl_name);
                        break;

                case TI_CLK_MUX:
                        _ti_clkctrl_setup_mux(provider, node, data->offset,
                                              bits, reg, clkctrl_name);
                        break;

                default:
                        pr_err("%s: bad subclk type: %d\n", __func__,
                               bits->type);
                        return;
                }
                bits++;
        }
}

static void __init _clkctrl_add_provider(void *data,
                                         struct device_node *np)
{
        of_clk_add_hw_provider(np, _ti_omap4_clkctrl_xlate, data);
}

/* Get clock name based on compatible string for clkctrl */
static char * __init clkctrl_get_name(struct device_node *np)
{
        struct property *prop;
        const int prefix_len = 11;
        const char *compat;
        char *name;

        of_property_for_each_string(np, "compatible", prop, compat) {
                if (!strncmp("ti,clkctrl-", compat, prefix_len)) {
                        /* Two letter minimum name length for l3, l4 etc */
                        if (strnlen(compat + prefix_len, 16) < 2)
                                continue;
                        name = kasprintf(GFP_KERNEL, "%s", compat + prefix_len);
                        if (!name)
                                continue;
                        strreplace(name, '-', '_');

                        return name;
                }
        }

        return NULL;
}

static void __init _ti_omap4_clkctrl_setup(struct device_node *node)
{
        struct omap_clkctrl_provider *provider;
        const struct omap_clkctrl_data *data = default_clkctrl_data;
        const struct omap_clkctrl_reg_data *reg_data;
        struct clk_init_data init = { NULL };
        struct clk_hw_omap *hw;
        struct clk *clk;
        struct omap_clkctrl_clk *clkctrl_clk = NULL;
        const __be32 *addrp;
        bool legacy_naming;
        char *clkctrl_name;
        u32 addr;
        int ret;
        char *c;
        u16 soc_mask = 0;

        if (!(ti_clk_get_features()->flags & TI_CLK_CLKCTRL_COMPAT) &&
            of_node_name_eq(node, "clk"))
                ti_clk_features.flags |= TI_CLK_CLKCTRL_COMPAT;

        addrp = of_get_address(node, 0, NULL, NULL);
        addr = (u32)of_translate_address(node, addrp);

#ifdef CONFIG_ARCH_OMAP4
        if (of_machine_is_compatible("ti,omap4"))
                data = omap4_clkctrl_data;
#endif
#ifdef CONFIG_SOC_OMAP5
        if (of_machine_is_compatible("ti,omap5"))
                data = omap5_clkctrl_data;
#endif
#ifdef CONFIG_SOC_DRA7XX
        if (of_machine_is_compatible("ti,dra7")) {
                if (ti_clk_get_features()->flags & TI_CLK_CLKCTRL_COMPAT)
                        data = dra7_clkctrl_compat_data;
                else
                        data = dra7_clkctrl_data;
        }

        if (of_machine_is_compatible("ti,dra72"))
                soc_mask = CLKF_SOC_DRA72;
        if (of_machine_is_compatible("ti,dra74"))
                soc_mask = CLKF_SOC_DRA74;
        if (of_machine_is_compatible("ti,dra76"))
                soc_mask = CLKF_SOC_DRA76;
#endif
#ifdef CONFIG_SOC_AM33XX
        if (of_machine_is_compatible("ti,am33xx")) {
                if (ti_clk_get_features()->flags & TI_CLK_CLKCTRL_COMPAT)
                        data = am3_clkctrl_compat_data;
                else
                        data = am3_clkctrl_data;
        }
#endif
#ifdef CONFIG_SOC_AM43XX
        if (of_machine_is_compatible("ti,am4372")) {
                if (ti_clk_get_features()->flags & TI_CLK_CLKCTRL_COMPAT)
                        data = am4_clkctrl_compat_data;
                else
                        data = am4_clkctrl_data;
        }

        if (of_machine_is_compatible("ti,am438x")) {
                if (ti_clk_get_features()->flags & TI_CLK_CLKCTRL_COMPAT)
                        data = am438x_clkctrl_compat_data;
                else
                        data = am438x_clkctrl_data;
        }
#endif
#ifdef CONFIG_SOC_TI81XX
        if (of_machine_is_compatible("ti,dm814"))
                data = dm814_clkctrl_data;

        if (of_machine_is_compatible("ti,dm816"))
                data = dm816_clkctrl_data;
#endif

        if (ti_clk_get_features()->flags & TI_CLK_DEVICE_TYPE_GP)
                soc_mask |= CLKF_SOC_NONSEC;

        while (data->addr) {
                if (addr == data->addr)
                        break;

                data++;
        }

        if (!data->addr) {
                pr_err("%pOF not found from clkctrl data.\n", node);
                return;
        }

        provider = kzalloc(sizeof(*provider), GFP_KERNEL);
        if (!provider)
                return;

        provider->base = of_iomap(node, 0);

        legacy_naming = ti_clk_get_features()->flags & TI_CLK_CLKCTRL_COMPAT;
        clkctrl_name = clkctrl_get_name(node);
        if (clkctrl_name) {
                provider->clkdm_name = kasprintf(GFP_KERNEL,
                                                 "%s_clkdm", clkctrl_name);
                goto clkdm_found;
        }

        /*
         * The code below can be removed when all clkctrl nodes use domain
         * specific compatible proprerty and standard clock node naming
         */
        if (legacy_naming) {
                provider->clkdm_name = kasprintf(GFP_KERNEL, "%pOFnxxx", node->parent);
                if (!provider->clkdm_name) {
                        kfree(provider);
                        return;
                }

                /*
                 * Create default clkdm name, replace _cm from end of parent
                 * node name with _clkdm
                 */
                provider->clkdm_name[strlen(provider->clkdm_name) - 2] = 0;
        } else {
                provider->clkdm_name = kasprintf(GFP_KERNEL, "%pOFn", node);
                if (!provider->clkdm_name) {
                        kfree(provider);
                        return;
                }

                /*
                 * Create default clkdm name, replace _clkctrl from end of
                 * node name with _clkdm
                 */
                provider->clkdm_name[strlen(provider->clkdm_name) - 7] = 0;
        }

        strcat(provider->clkdm_name, "clkdm");

        /* Replace any dash from the clkdm name with underscore */
        c = provider->clkdm_name;

        while (*c) {
                if (*c == '-')
                        *c = '_';
                c++;
        }
clkdm_found:
        INIT_LIST_HEAD(&provider->clocks);

        /* Generate clocks */
        reg_data = data->regs;

        while (reg_data->parent) {
                if ((reg_data->flags & CLKF_SOC_MASK) &&
                    (reg_data->flags & soc_mask) == 0) {
                        reg_data++;
                        continue;
                }

                hw = kzalloc(sizeof(*hw), GFP_KERNEL);
                if (!hw)
                        return;

                hw->enable_reg.ptr = provider->base + reg_data->offset;

                _ti_clkctrl_setup_subclks(provider, node, reg_data,
                                          hw->enable_reg.ptr, clkctrl_name);

                if (reg_data->flags & CLKF_SW_SUP)
                        hw->enable_bit = MODULEMODE_SWCTRL;
                if (reg_data->flags & CLKF_HW_SUP)
                        hw->enable_bit = MODULEMODE_HWCTRL;
                if (reg_data->flags & CLKF_NO_IDLEST)
                        set_bit(NO_IDLEST, &hw->flags);

                if (reg_data->clkdm_name)
                        hw->clkdm_name = reg_data->clkdm_name;
                else
                        hw->clkdm_name = provider->clkdm_name;

                init.parent_names = &reg_data->parent;
                init.num_parents = 1;
                init.flags = 0;
                if (reg_data->flags & CLKF_SET_RATE_PARENT)
                        init.flags |= CLK_SET_RATE_PARENT;

                init.name = clkctrl_get_clock_name(node, clkctrl_name,
                                                   reg_data->offset, 0,
                                                   legacy_naming);
                if (!init.name)
                        goto cleanup;

                clkctrl_clk = kzalloc(sizeof(*clkctrl_clk), GFP_KERNEL);
                if (!clkctrl_clk)
                        goto cleanup;

                init.ops = &omap4_clkctrl_clk_ops;
                hw->hw.init = &init;

                clk = ti_clk_register_omap_hw(NULL, &hw->hw, init.name);
                if (IS_ERR_OR_NULL(clk))
                        goto cleanup;

                clkctrl_clk->reg_offset = reg_data->offset;
                clkctrl_clk->clk = &hw->hw;

                list_add(&clkctrl_clk->node, &provider->clocks);

                reg_data++;
        }

        ret = of_clk_add_hw_provider(node, _ti_omap4_clkctrl_xlate, provider);
        if (ret == -EPROBE_DEFER)
                ti_clk_retry_init(node, provider, _clkctrl_add_provider);

        kfree(clkctrl_name);

        return;

cleanup:
        kfree(hw);
        kfree(init.name);
        kfree(clkctrl_name);
        kfree(clkctrl_clk);
}
CLK_OF_DECLARE(ti_omap4_clkctrl_clock, "ti,clkctrl",
               _ti_omap4_clkctrl_setup);

/**
 * ti_clk_is_in_standby - Check if clkctrl clock is in standby or not
 * @clk: clock to check standby status for
 *
 * Finds whether the provided clock is in standby mode or not. Returns
 * true if the provided clock is a clkctrl type clock and it is in standby,
 * false otherwise.
 */
bool ti_clk_is_in_standby(struct clk *clk)
{
        struct clk_hw *hw;
        struct clk_hw_omap *hwclk;
        u32 val;

        hw = __clk_get_hw(clk);

        if (!omap2_clk_is_hw_omap(hw))
                return false;

        hwclk = to_clk_hw_omap(hw);

        val = ti_clk_ll_ops->clk_readl(&hwclk->enable_reg);

        if (val & OMAP4_STBYST_MASK)
                return true;

        return false;
}
EXPORT_SYMBOL_GPL(ti_clk_is_in_standby);