/*
 * Synopsys HSDK SDP Generic PLL clock driver
 *
 * Copyright (C) 2017 Synopsys
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#define CGU_PLL_CTRL    0x000 /* ARC PLL control register */
#define CGU_PLL_STATUS  0x004 /* ARC PLL status register */
#define CGU_PLL_FMEAS   0x008 /* ARC PLL frequency measurement register */
#define CGU_PLL_MON     0x00C /* ARC PLL monitor register */

#define CGU_PLL_CTRL_ODIV_SHIFT         2
#define CGU_PLL_CTRL_IDIV_SHIFT         4
#define CGU_PLL_CTRL_FBDIV_SHIFT        9
#define CGU_PLL_CTRL_BAND_SHIFT         20

#define CGU_PLL_CTRL_ODIV_MASK          GENMASK(3, CGU_PLL_CTRL_ODIV_SHIFT)
#define CGU_PLL_CTRL_IDIV_MASK          GENMASK(8, CGU_PLL_CTRL_IDIV_SHIFT)
#define CGU_PLL_CTRL_FBDIV_MASK         GENMASK(15, CGU_PLL_CTRL_FBDIV_SHIFT)

#define CGU_PLL_CTRL_PD                 BIT(0)
#define CGU_PLL_CTRL_BYPASS             BIT(1)

#define CGU_PLL_STATUS_LOCK             BIT(0)
#define CGU_PLL_STATUS_ERR              BIT(1)

#define HSDK_PLL_MAX_LOCK_TIME          100 /* 100 us */

#define CGU_PLL_SOURCE_MAX              1

#define CORE_IF_CLK_THRESHOLD_HZ        500000000
#define CREG_CORE_IF_CLK_DIV_1          0x0
#define CREG_CORE_IF_CLK_DIV_2          0x1

struct hsdk_pll_cfg {
        u32 rate;
        u32 idiv;
        u32 fbdiv;
        u32 odiv;
        u32 band;
};

static const struct hsdk_pll_cfg asdt_pll_cfg[] = {
        { 100000000,  0, 11, 3, 0 },
        { 133000000,  0, 15, 3, 0 },
        { 200000000,  1, 47, 3, 0 },
        { 233000000,  1, 27, 2, 0 },
        { 300000000,  1, 35, 2, 0 },
        { 333000000,  1, 39, 2, 0 },
        { 400000000,  1, 47, 2, 0 },
        { 500000000,  0, 14, 1, 0 },
        { 600000000,  0, 17, 1, 0 },
        { 700000000,  0, 20, 1, 0 },
        { 800000000,  0, 23, 1, 0 },
        { 900000000,  1, 26, 0, 0 },
        { 1000000000, 1, 29, 0, 0 },
        { 1100000000, 1, 32, 0, 0 },
        { 1200000000, 1, 35, 0, 0 },
        { 1300000000, 1, 38, 0, 0 },
        { 1400000000, 1, 41, 0, 0 },
        { 1500000000, 1, 44, 0, 0 },
        { 1600000000, 1, 47, 0, 0 },
        {}
};

static const struct hsdk_pll_cfg hdmi_pll_cfg[] = {
        { 297000000,  0, 21, 2, 0 },
        { 540000000,  0, 19, 1, 0 },
        { 594000000,  0, 21, 1, 0 },
        {}
};

struct hsdk_pll_clk {
        struct clk_hw hw;
        void __iomem *regs;
        void __iomem *spec_regs;
        const struct hsdk_pll_devdata *pll_devdata;
        struct device *dev;
};

struct hsdk_pll_devdata {
        const struct hsdk_pll_cfg *pll_cfg;
        int (*update_rate)(struct hsdk_pll_clk *clk, unsigned long rate,
                           const struct hsdk_pll_cfg *cfg);
};

static int hsdk_pll_core_update_rate(struct hsdk_pll_clk *, unsigned long,
                                     const struct hsdk_pll_cfg *);
static int hsdk_pll_comm_update_rate(struct hsdk_pll_clk *, unsigned long,
                                     const struct hsdk_pll_cfg *);

static const struct hsdk_pll_devdata core_pll_devdata = {
        .pll_cfg = asdt_pll_cfg,
        .update_rate = hsdk_pll_core_update_rate,
};

static const struct hsdk_pll_devdata sdt_pll_devdata = {
        .pll_cfg = asdt_pll_cfg,
        .update_rate = hsdk_pll_comm_update_rate,
};

static const struct hsdk_pll_devdata hdmi_pll_devdata = {
        .pll_cfg = hdmi_pll_cfg,
        .update_rate = hsdk_pll_comm_update_rate,
};

static inline void hsdk_pll_write(struct hsdk_pll_clk *clk, u32 reg, u32 val)
{
        iowrite32(val, clk->regs + reg);
}

static inline u32 hsdk_pll_read(struct hsdk_pll_clk *clk, u32 reg)
{
        return ioread32(clk->regs + reg);
}

static inline void hsdk_pll_set_cfg(struct hsdk_pll_clk *clk,
                                    const struct hsdk_pll_cfg *cfg)
{
        u32 val = 0;

        /* Powerdown and Bypass bits should be cleared */
        val |= cfg->idiv << CGU_PLL_CTRL_IDIV_SHIFT;
        val |= cfg->fbdiv << CGU_PLL_CTRL_FBDIV_SHIFT;
        val |= cfg->odiv << CGU_PLL_CTRL_ODIV_SHIFT;
        val |= cfg->band << CGU_PLL_CTRL_BAND_SHIFT;

        dev_dbg(clk->dev, "write configuration: %#x\n", val);

        hsdk_pll_write(clk, CGU_PLL_CTRL, val);
}

static inline bool hsdk_pll_is_locked(struct hsdk_pll_clk *clk)
{
        return !!(hsdk_pll_read(clk, CGU_PLL_STATUS) & CGU_PLL_STATUS_LOCK);
}

static inline bool hsdk_pll_is_err(struct hsdk_pll_clk *clk)
{
        return !!(hsdk_pll_read(clk, CGU_PLL_STATUS) & CGU_PLL_STATUS_ERR);
}

static inline struct hsdk_pll_clk *to_hsdk_pll_clk(struct clk_hw *hw)
{
        return container_of(hw, struct hsdk_pll_clk, hw);
}

static unsigned long hsdk_pll_recalc_rate(struct clk_hw *hw,
                                          unsigned long parent_rate)
{
        u32 val;
        u64 rate;
        u32 idiv, fbdiv, odiv;
        struct hsdk_pll_clk *clk = to_hsdk_pll_clk(hw);

        val = hsdk_pll_read(clk, CGU_PLL_CTRL);

        dev_dbg(clk->dev, "current configuration: %#x\n", val);

        /* Check if PLL is disabled */
        if (val & CGU_PLL_CTRL_PD)
                return 0;

        /* Check if PLL is bypassed */
        if (val & CGU_PLL_CTRL_BYPASS)
                return parent_rate;

        /* input divider = reg.idiv + 1 */
        idiv = 1 + ((val & CGU_PLL_CTRL_IDIV_MASK) >> CGU_PLL_CTRL_IDIV_SHIFT);
        /* fb divider = 2*(reg.fbdiv + 1) */
        fbdiv = 2 * (1 + ((val & CGU_PLL_CTRL_FBDIV_MASK) >> CGU_PLL_CTRL_FBDIV_SHIFT));
        /* output divider = 2^(reg.odiv) */
        odiv = 1 << ((val & CGU_PLL_CTRL_ODIV_MASK) >> CGU_PLL_CTRL_ODIV_SHIFT);

        rate = (u64)parent_rate * fbdiv;
        do_div(rate, idiv * odiv);

        return rate;
}

static long hsdk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
                                unsigned long *prate)
{
        int i;
        unsigned long best_rate;
        struct hsdk_pll_clk *clk = to_hsdk_pll_clk(hw);
        const struct hsdk_pll_cfg *pll_cfg = clk->pll_devdata->pll_cfg;

        if (pll_cfg[0].rate == 0)
                return -EINVAL;

        best_rate = pll_cfg[0].rate;

        for (i = 1; pll_cfg[i].rate != 0; i++) {
                if (abs(rate - pll_cfg[i].rate) < abs(rate - best_rate))
                        best_rate = pll_cfg[i].rate;
        }

        dev_dbg(clk->dev, "chosen best rate: %lu\n", best_rate);

        return best_rate;
}

static int hsdk_pll_comm_update_rate(struct hsdk_pll_clk *clk,
                                     unsigned long rate,
                                     const struct hsdk_pll_cfg *cfg)
{
        hsdk_pll_set_cfg(clk, cfg);

        /*
         * Wait until CGU relocks and check error status.
         * If after timeout CGU is unlocked yet return error.
         */
        udelay(HSDK_PLL_MAX_LOCK_TIME);
        if (!hsdk_pll_is_locked(clk))
                return -ETIMEDOUT;

        if (hsdk_pll_is_err(clk))
                return -EINVAL;

        return 0;
}

static int hsdk_pll_core_update_rate(struct hsdk_pll_clk *clk,
                                     unsigned long rate,
                                     const struct hsdk_pll_cfg *cfg)
{
        /*
         * When core clock exceeds 500MHz, the divider for the interface
         * clock must be programmed to div-by-2.
         */
        if (rate > CORE_IF_CLK_THRESHOLD_HZ)
                iowrite32(CREG_CORE_IF_CLK_DIV_2, clk->spec_regs);

        hsdk_pll_set_cfg(clk, cfg);

        /*
         * Wait until CGU relocks and check error status.
         * If after timeout CGU is unlocked yet return error.
         */
        udelay(HSDK_PLL_MAX_LOCK_TIME);
        if (!hsdk_pll_is_locked(clk))
                return -ETIMEDOUT;

        if (hsdk_pll_is_err(clk))
                return -EINVAL;

        /*
         * Program divider to div-by-1 if we succesfuly set core clock below
         * 500MHz threshold.
         */
        if (rate <= CORE_IF_CLK_THRESHOLD_HZ)
                iowrite32(CREG_CORE_IF_CLK_DIV_1, clk->spec_regs);

        return 0;
}

static int hsdk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
                             unsigned long parent_rate)
{
        int i;
        struct hsdk_pll_clk *clk = to_hsdk_pll_clk(hw);
        const struct hsdk_pll_cfg *pll_cfg = clk->pll_devdata->pll_cfg;

        for (i = 0; pll_cfg[i].rate != 0; i++) {
                if (pll_cfg[i].rate == rate) {
                        return clk->pll_devdata->update_rate(clk, rate,
                                                             &pll_cfg[i]);
                }
        }

        dev_err(clk->dev, "invalid rate=%ld, parent_rate=%ld\n", rate,
                        parent_rate);

        return -EINVAL;
}

static const struct clk_ops hsdk_pll_ops = {
        .recalc_rate = hsdk_pll_recalc_rate,
        .round_rate = hsdk_pll_round_rate,
        .set_rate = hsdk_pll_set_rate,
};

static int hsdk_pll_clk_probe(struct platform_device *pdev)
{
        int ret;
        struct resource *mem;
        const char *parent_name;
        unsigned int num_parents;
        struct hsdk_pll_clk *pll_clk;
        struct clk_init_data init = { };
        struct device *dev = &pdev->dev;

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

        mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        pll_clk->regs = devm_ioremap_resource(dev, mem);
        if (IS_ERR(pll_clk->regs))
                return PTR_ERR(pll_clk->regs);

        init.name = dev->of_node->name;
        init.ops = &hsdk_pll_ops;
        parent_name = of_clk_get_parent_name(dev->of_node, 0);
        init.parent_names = &parent_name;
        num_parents = of_clk_get_parent_count(dev->of_node);
        if (num_parents == 0 || num_parents > CGU_PLL_SOURCE_MAX) {
                dev_err(dev, "wrong clock parents number: %u\n", num_parents);
                return -EINVAL;
        }
        init.num_parents = num_parents;

        pll_clk->hw.init = &init;
        pll_clk->dev = dev;
        pll_clk->pll_devdata = of_device_get_match_data(dev);

        if (!pll_clk->pll_devdata) {
                dev_err(dev, "No OF match data provided\n");
                return -EINVAL;
        }

        ret = devm_clk_hw_register(dev, &pll_clk->hw);
        if (ret) {
                dev_err(dev, "failed to register %s clock\n", init.name);
                return ret;
        }

        return of_clk_add_hw_provider(dev->of_node, of_clk_hw_simple_get,
                        &pll_clk->hw);
}

static int hsdk_pll_clk_remove(struct platform_device *pdev)
{
        of_clk_del_provider(pdev->dev.of_node);
        return 0;
}

static void __init of_hsdk_pll_clk_setup(struct device_node *node)
{
        int ret;
        const char *parent_name;
        unsigned int num_parents;
        struct hsdk_pll_clk *pll_clk;
        struct clk_init_data init = { };

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

        pll_clk->regs = of_iomap(node, 0);
        if (!pll_clk->regs) {
                pr_err("failed to map pll registers\n");
                goto err_free_pll_clk;
        }

        pll_clk->spec_regs = of_iomap(node, 1);
        if (!pll_clk->spec_regs) {
                pr_err("failed to map pll registers\n");
                goto err_unmap_comm_regs;
        }

        init.name = node->name;
        init.ops = &hsdk_pll_ops;
        parent_name = of_clk_get_parent_name(node, 0);
        init.parent_names = &parent_name;
        num_parents = of_clk_get_parent_count(node);
        if (num_parents > CGU_PLL_SOURCE_MAX) {
                pr_err("too much clock parents: %u\n", num_parents);
                goto err_unmap_spec_regs;
        }
        init.num_parents = num_parents;

        pll_clk->hw.init = &init;
        pll_clk->pll_devdata = &core_pll_devdata;

        ret = clk_hw_register(NULL, &pll_clk->hw);
        if (ret) {
                pr_err("failed to register %pOFn clock\n", node);
                goto err_unmap_spec_regs;
        }

        ret = of_clk_add_hw_provider(node, of_clk_hw_simple_get, &pll_clk->hw);
        if (ret) {
                pr_err("failed to add hw provider for %pOFn clock\n", node);
                goto err_unmap_spec_regs;
        }

        return;

err_unmap_spec_regs:
        iounmap(pll_clk->spec_regs);
err_unmap_comm_regs:
        iounmap(pll_clk->regs);
err_free_pll_clk:
        kfree(pll_clk);
}

/* Core PLL needed early for ARC cpus timers */
CLK_OF_DECLARE(hsdk_pll_clock, "snps,hsdk-core-pll-clock",
of_hsdk_pll_clk_setup);

static const struct of_device_id hsdk_pll_clk_id[] = {
        { .compatible = "snps,hsdk-gp-pll-clock", .data = &sdt_pll_devdata},
        { .compatible = "snps,hsdk-hdmi-pll-clock", .data = &hdmi_pll_devdata},
        { }
};

static struct platform_driver hsdk_pll_clk_driver = {
        .driver = {
                .name = "hsdk-gp-pll-clock",
                .of_match_table = hsdk_pll_clk_id,
        },
        .probe = hsdk_pll_clk_probe,
        .remove = hsdk_pll_clk_remove,
};
builtin_platform_driver(hsdk_pll_clk_driver);