/*
 * Copyright (c) 2014, Fuzhou Rockchip Electronics Co., Ltd
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */

#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/mmc/host.h>
#include <linux/of_address.h>
#include <linux/mmc/slot-gpio.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>

#include "dw_mmc.h"
#include "dw_mmc-pltfm.h"

#define RK3288_CLKGEN_DIV       2

struct dw_mci_rockchip_priv_data {
        struct clk              *drv_clk;
        struct clk              *sample_clk;
        int                     default_sample_phase;
        int                     num_phases;
};

static void dw_mci_rk3288_set_ios(struct dw_mci *host, struct mmc_ios *ios)
{
        struct dw_mci_rockchip_priv_data *priv = host->priv;
        int ret;
        unsigned int cclkin;
        u32 bus_hz;

        if (ios->clock == 0)
                return;

        /*
         * cclkin: source clock of mmc controller
         * bus_hz: card interface clock generated by CLKGEN
         * bus_hz = cclkin / RK3288_CLKGEN_DIV
         * ios->clock = (div == 0) ? bus_hz : (bus_hz / (2 * div))
         *
         * Note: div can only be 0 or 1, but div must be set to 1 for eMMC
         * DDR52 8-bit mode.
         */
        if (ios->bus_width == MMC_BUS_WIDTH_8 &&
            ios->timing == MMC_TIMING_MMC_DDR52)
                cclkin = 2 * ios->clock * RK3288_CLKGEN_DIV;
        else
                cclkin = ios->clock * RK3288_CLKGEN_DIV;

        ret = clk_set_rate(host->ciu_clk, cclkin);
        if (ret)
                dev_warn(host->dev, "failed to set rate %uHz\n", ios->clock);

        bus_hz = clk_get_rate(host->ciu_clk) / RK3288_CLKGEN_DIV;
        if (bus_hz != host->bus_hz) {
                host->bus_hz = bus_hz;
                /* force dw_mci_setup_bus() */
                host->current_speed = 0;
        }

        /* Make sure we use phases which we can enumerate with */
        if (!IS_ERR(priv->sample_clk))
                clk_set_phase(priv->sample_clk, priv->default_sample_phase);

        /*
         * Set the drive phase offset based on speed mode to achieve hold times.
         *
         * NOTE: this is _not_ a value that is dynamically tuned and is also
         * _not_ a value that will vary from board to board.  It is a value
         * that could vary between different SoC models if they had massively
         * different output clock delays inside their dw_mmc IP block (delay_o),
         * but since it's OK to overshoot a little we don't need to do complex
         * calculations and can pick values that will just work for everyone.
         *
         * When picking values we'll stick with picking 0/90/180/270 since
         * those can be made very accurately on all known Rockchip SoCs.
         *
         * Note that these values match values from the DesignWare Databook
         * tables for the most part except for SDR12 and "ID mode".  For those
         * two modes the databook calculations assume a clock in of 50MHz.  As
         * seen above, we always use a clock in rate that is exactly the
         * card's input clock (times RK3288_CLKGEN_DIV, but that gets divided
         * back out before the controller sees it).
         *
         * From measurement of a single device, it appears that delay_o is
         * about .5 ns.  Since we try to leave a bit of margin, it's expected
         * that numbers here will be fine even with much larger delay_o
         * (the 1.4 ns assumed by the DesignWare Databook would result in the
         * same results, for instance).
         */
        if (!IS_ERR(priv->drv_clk)) {
                int phase;

                /*
                 * In almost all cases a 90 degree phase offset will provide
                 * sufficient hold times across all valid input clock rates
                 * assuming delay_o is not absurd for a given SoC.  We'll use
                 * that as a default.
                 */
                phase = 90;

                switch (ios->timing) {
                case MMC_TIMING_MMC_DDR52:
                        /*
                         * Since clock in rate with MMC_DDR52 is doubled when
                         * bus width is 8 we need to double the phase offset
                         * to get the same timings.
                         */
                        if (ios->bus_width == MMC_BUS_WIDTH_8)
                                phase = 180;
                        break;
                case MMC_TIMING_UHS_SDR104:
                case MMC_TIMING_MMC_HS200:
                        /*
                         * In the case of 150 MHz clock (typical max for
                         * Rockchip SoCs), 90 degree offset will add a delay
                         * of 1.67 ns.  That will meet min hold time of .8 ns
                         * as long as clock output delay is < .87 ns.  On
                         * SoCs measured this seems to be OK, but it doesn't
                         * hurt to give margin here, so we use 180.
                         */
                        phase = 180;
                        break;
                }

                clk_set_phase(priv->drv_clk, phase);
        }
}

#define TUNING_ITERATION_TO_PHASE(i, num_phases) \
                (DIV_ROUND_UP((i) * 360, num_phases))

static int dw_mci_rk3288_execute_tuning(struct dw_mci_slot *slot, u32 opcode)
{
        struct dw_mci *host = slot->host;
        struct dw_mci_rockchip_priv_data *priv = host->priv;
        struct mmc_host *mmc = slot->mmc;
        int ret = 0;
        int i;
        bool v, prev_v = 0, first_v;
        struct range_t {
                int start;
                int end; /* inclusive */
        };
        struct range_t *ranges;
        unsigned int range_count = 0;
        int longest_range_len = -1;
        int longest_range = -1;
        int middle_phase;

        if (IS_ERR(priv->sample_clk)) {
                dev_err(host->dev, "Tuning clock (sample_clk) not defined.\n");
                return -EIO;
        }

        ranges = kmalloc_array(priv->num_phases / 2 + 1,
                               sizeof(*ranges), GFP_KERNEL);
        if (!ranges)
                return -ENOMEM;

        /* Try each phase and extract good ranges */
        for (i = 0; i < priv->num_phases; ) {
                clk_set_phase(priv->sample_clk,
                              TUNING_ITERATION_TO_PHASE(i, priv->num_phases));

                v = !mmc_send_tuning(mmc, opcode, NULL);

                if (i == 0)
                        first_v = v;

                if ((!prev_v) && v) {
                        range_count++;
                        ranges[range_count-1].start = i;
                }
                if (v) {
                        ranges[range_count-1].end = i;
                        i++;
                } else if (i == priv->num_phases - 1) {
                        /* No extra skipping rules if we're at the end */
                        i++;
                } else {
                        /*
                         * No need to check too close to an invalid
                         * one since testing bad phases is slow.  Skip
                         * 20 degrees.
                         */
                        i += DIV_ROUND_UP(20 * priv->num_phases, 360);

                        /* Always test the last one */
                        if (i >= priv->num_phases)
                                i = priv->num_phases - 1;
                }

                prev_v = v;
        }

        if (range_count == 0) {
                dev_warn(host->dev, "All phases bad!");
                ret = -EIO;
                goto free;
        }

        /* wrap around case, merge the end points */
        if ((range_count > 1) && first_v && v) {
                ranges[0].start = ranges[range_count-1].start;
                range_count--;
        }

        if (ranges[0].start == 0 && ranges[0].end == priv->num_phases - 1) {
                clk_set_phase(priv->sample_clk, priv->default_sample_phase);
                dev_info(host->dev, "All phases work, using default phase %d.",
                         priv->default_sample_phase);
                goto free;
        }

        /* Find the longest range */
        for (i = 0; i < range_count; i++) {
                int len = (ranges[i].end - ranges[i].start + 1);

                if (len < 0)
                        len += priv->num_phases;

                if (longest_range_len < len) {
                        longest_range_len = len;
                        longest_range = i;
                }

                dev_dbg(host->dev, "Good phase range %d-%d (%d len)\n",
                        TUNING_ITERATION_TO_PHASE(ranges[i].start,
                                                  priv->num_phases),
                        TUNING_ITERATION_TO_PHASE(ranges[i].end,
                                                  priv->num_phases),
                        len
                );
        }

        dev_dbg(host->dev, "Best phase range %d-%d (%d len)\n",
                TUNING_ITERATION_TO_PHASE(ranges[longest_range].start,
                                          priv->num_phases),
                TUNING_ITERATION_TO_PHASE(ranges[longest_range].end,
                                          priv->num_phases),
                longest_range_len
        );

        middle_phase = ranges[longest_range].start + longest_range_len / 2;
        middle_phase %= priv->num_phases;
        dev_info(host->dev, "Successfully tuned phase to %d\n",
                 TUNING_ITERATION_TO_PHASE(middle_phase, priv->num_phases));

        clk_set_phase(priv->sample_clk,
                      TUNING_ITERATION_TO_PHASE(middle_phase,
                                                priv->num_phases));

free:
        kfree(ranges);
        return ret;
}

static int dw_mci_rk3288_parse_dt(struct dw_mci *host)
{
        struct device_node *np = host->dev->of_node;
        struct dw_mci_rockchip_priv_data *priv;

        priv = devm_kzalloc(host->dev, sizeof(*priv), GFP_KERNEL);
        if (!priv)
                return -ENOMEM;

        if (of_property_read_u32(np, "rockchip,desired-num-phases",
                                        &priv->num_phases))
                priv->num_phases = 360;

        if (of_property_read_u32(np, "rockchip,default-sample-phase",
                                        &priv->default_sample_phase))
                priv->default_sample_phase = 0;

        priv->drv_clk = devm_clk_get(host->dev, "ciu-drive");
        if (IS_ERR(priv->drv_clk))
                dev_dbg(host->dev, "ciu-drive not available\n");

        priv->sample_clk = devm_clk_get(host->dev, "ciu-sample");
        if (IS_ERR(priv->sample_clk))
                dev_dbg(host->dev, "ciu-sample not available\n");

        host->priv = priv;

        return 0;
}

static int dw_mci_rockchip_init(struct dw_mci *host)
{
        /* It is slot 8 on Rockchip SoCs */
        host->sdio_id0 = 8;

        if (of_device_is_compatible(host->dev->of_node,
                                    "rockchip,rk3288-dw-mshc"))
                host->bus_hz /= RK3288_CLKGEN_DIV;

        return 0;
}

/* Common capabilities of RK3288 SoC */
static unsigned long dw_mci_rk3288_dwmmc_caps[4] = {
        MMC_CAP_CMD23,
        MMC_CAP_CMD23,
        MMC_CAP_CMD23,
        MMC_CAP_CMD23,
};

static const struct dw_mci_drv_data rk2928_drv_data = {
        .init                   = dw_mci_rockchip_init,
};

static const struct dw_mci_drv_data rk3288_drv_data = {
        .caps                   = dw_mci_rk3288_dwmmc_caps,
        .num_caps               = ARRAY_SIZE(dw_mci_rk3288_dwmmc_caps),
        .set_ios                = dw_mci_rk3288_set_ios,
        .execute_tuning         = dw_mci_rk3288_execute_tuning,
        .parse_dt               = dw_mci_rk3288_parse_dt,
        .init                   = dw_mci_rockchip_init,
};

static const struct of_device_id dw_mci_rockchip_match[] = {
        { .compatible = "rockchip,rk2928-dw-mshc",
                .data = &rk2928_drv_data },
        { .compatible = "rockchip,rk3288-dw-mshc",
                .data = &rk3288_drv_data },
        {},
};
MODULE_DEVICE_TABLE(of, dw_mci_rockchip_match);

static int dw_mci_rockchip_probe(struct platform_device *pdev)
{
        const struct dw_mci_drv_data *drv_data;
        const struct of_device_id *match;
        int ret;

        if (!pdev->dev.of_node)
                return -ENODEV;

        match = of_match_node(dw_mci_rockchip_match, pdev->dev.of_node);
        drv_data = match->data;

        pm_runtime_get_noresume(&pdev->dev);
        pm_runtime_set_active(&pdev->dev);
        pm_runtime_enable(&pdev->dev);
        pm_runtime_set_autosuspend_delay(&pdev->dev, 50);
        pm_runtime_use_autosuspend(&pdev->dev);

        ret = dw_mci_pltfm_register(pdev, drv_data);
        if (ret) {
                pm_runtime_disable(&pdev->dev);
                pm_runtime_set_suspended(&pdev->dev);
                pm_runtime_put_noidle(&pdev->dev);
                return ret;
        }

        pm_runtime_put_autosuspend(&pdev->dev);

        return 0;
}

static int dw_mci_rockchip_remove(struct platform_device *pdev)
{
        pm_runtime_get_sync(&pdev->dev);
        pm_runtime_disable(&pdev->dev);
        pm_runtime_put_noidle(&pdev->dev);

        return dw_mci_pltfm_remove(pdev);
}

static const struct dev_pm_ops dw_mci_rockchip_dev_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
                                pm_runtime_force_resume)
        SET_RUNTIME_PM_OPS(dw_mci_runtime_suspend,
                           dw_mci_runtime_resume,
                           NULL)
};

static struct platform_driver dw_mci_rockchip_pltfm_driver = {
        .probe          = dw_mci_rockchip_probe,
        .remove         = dw_mci_rockchip_remove,
        .driver         = {
                .name           = "dwmmc_rockchip",
                .of_match_table = dw_mci_rockchip_match,
                .pm             = &dw_mci_rockchip_dev_pm_ops,
        },
};

module_platform_driver(dw_mci_rockchip_pltfm_driver);

MODULE_AUTHOR("Addy Ke <addy.ke@rock-chips.com>");
MODULE_DESCRIPTION("Rockchip Specific DW-MSHC Driver Extension");
MODULE_ALIAS("platform:dwmmc_rockchip");
MODULE_LICENSE("GPL v2");