// SPDX-License-Identifier: GPL-2.0
/*
 * Qualcomm Ramp Controller driver
 * Copyright (c) 2022, AngeloGioacchino Del Regno
 *                     <angelogioacchino.delregno@collabora.com>
 */

#include <linux/bitfield.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/types.h>

#define RC_UPDATE_EN            BIT(0)
#define RC_ROOT_EN              BIT(1)

#define RC_REG_CFG_UPDATE       0x60
#define RC_CFG_UPDATE_EN        BIT(8)
#define RC_CFG_ACK              GENMASK(31, 16)

#define RC_DCVS_CFG_SID         2
#define RC_LINK_SID             3
#define RC_LMH_SID              6
#define RC_DFS_SID              14

#define RC_UPDATE_TIMEOUT_US    500

/**
 * struct qcom_ramp_controller_desc - SoC specific parameters
 * @cfg_dfs_sid:      Dynamic Frequency Scaling SID configuration
 * @cfg_link_sid:     Link SID configuration
 * @cfg_lmh_sid:      Limits Management hardware SID configuration
 * @cfg_ramp_en:      Ramp Controller enable sequence
 * @cfg_ramp_dis:     Ramp Controller disable sequence
 * @cmd_reg:          Command register offset
 * @num_dfs_sids:     Number of DFS SIDs (max 8)
 * @num_link_sids:    Number of Link SIDs (max 3)
 * @num_lmh_sids:     Number of LMh SIDs (max 8)
 * @num_ramp_en:      Number of entries in enable sequence
 * @num_ramp_dis:     Number of entries in disable sequence
 */
struct qcom_ramp_controller_desc {
        const struct reg_sequence *cfg_dfs_sid;
        const struct reg_sequence *cfg_link_sid;
        const struct reg_sequence *cfg_lmh_sid;
        const struct reg_sequence *cfg_ramp_en;
        const struct reg_sequence *cfg_ramp_dis;
        u8 cmd_reg;
        u8 num_dfs_sids;
        u8 num_link_sids;
        u8 num_lmh_sids;
        u8 num_ramp_en;
        u8 num_ramp_dis;
};

/**
 * struct qcom_ramp_controller - Main driver structure
 * @regmap: Regmap handle
 * @desc:   SoC specific parameters
 */
struct qcom_ramp_controller {
        struct regmap *regmap;
        const struct qcom_ramp_controller_desc *desc;
};

/**
 * rc_wait_for_update() - Wait for Ramp Controller root update
 * @qrc: Main driver structure
 *
 * Return: Zero for success or negative number for failure
 */
static int rc_wait_for_update(struct qcom_ramp_controller *qrc)
{
        const struct qcom_ramp_controller_desc *d = qrc->desc;
        struct regmap *r = qrc->regmap;
        u32 val;
        int ret;

        ret = regmap_set_bits(r, d->cmd_reg, RC_ROOT_EN);
        if (ret)
                return ret;

        return regmap_read_poll_timeout(r, d->cmd_reg, val, !(val & RC_UPDATE_EN),
                                        1, RC_UPDATE_TIMEOUT_US);
}

/**
 * rc_set_cfg_update() - Ramp Controller configuration update
 * @qrc: Main driver structure
 * @ce: Configuration entry to update
 *
 * Return: Zero for success or negative number for failure
 */
static int rc_set_cfg_update(struct qcom_ramp_controller *qrc, u8 ce)
{
        const struct qcom_ramp_controller_desc *d = qrc->desc;
        struct regmap *r = qrc->regmap;
        u32 ack, val;
        int ret;

        /* The ack bit is between bits 16-31 of RC_REG_CFG_UPDATE */
        ack = FIELD_PREP(RC_CFG_ACK, BIT(ce));

        /* Write the configuration type first... */
        ret = regmap_set_bits(r, d->cmd_reg + RC_REG_CFG_UPDATE, ce);
        if (ret)
                return ret;

        /* ...and after that, enable the update bit to sync the changes */
        ret = regmap_set_bits(r, d->cmd_reg + RC_REG_CFG_UPDATE, RC_CFG_UPDATE_EN);
        if (ret)
                return ret;

        /* Wait for the changes to go through */
        ret = regmap_read_poll_timeout(r, d->cmd_reg + RC_REG_CFG_UPDATE, val,
                                       val & ack, 1, RC_UPDATE_TIMEOUT_US);
        if (ret)
                return ret;

        /*
         * Configuration update success! The CFG_UPDATE register will not be
         * cleared automatically upon applying the configuration, so we have
         * to do that manually in order to leave the ramp controller in a
         * predictable and clean state.
         */
        ret = regmap_write(r, d->cmd_reg + RC_REG_CFG_UPDATE, 0);
        if (ret)
                return ret;

        /* Wait for the update bit cleared ack */
        return regmap_read_poll_timeout(r, d->cmd_reg + RC_REG_CFG_UPDATE,
                                        val, !(val & RC_CFG_ACK), 1,
                                        RC_UPDATE_TIMEOUT_US);
}

/**
 * rc_write_cfg - Send configuration sequence
 * @qrc: Main driver structure
 * @seq: Register sequence to send before asking for update
 * @ce: Configuration SID
 * @nsids: Total number of SIDs
 *
 * Returns: Zero for success or negative number for error
 */
static int rc_write_cfg(struct qcom_ramp_controller *qrc,
                        const struct reg_sequence *seq,
                        u16 ce, u8 nsids)
{
        int ret;
        u8 i;

        /* Check if, and wait until the ramp controller is ready */
        ret = rc_wait_for_update(qrc);
        if (ret)
                return ret;

        /* Write the sequence */
        ret = regmap_multi_reg_write(qrc->regmap, seq, nsids);
        if (ret)
                return ret;

        /* Pull the trigger: do config update starting from the last sid */
        for (i = 0; i < nsids; i++) {
                ret = rc_set_cfg_update(qrc, (u8)ce - i);
                if (ret)
                        return ret;
        }

        return 0;
}

/**
 * rc_ramp_ctrl_enable() - Enable Ramp up/down Control
 * @qrc: Main driver structure
 *
 * Return: Zero for success or negative number for error
 */
static int rc_ramp_ctrl_enable(struct qcom_ramp_controller *qrc)
{
        const struct qcom_ramp_controller_desc *d = qrc->desc;
        int i, ret;

        for (i = 0; i < d->num_ramp_en; i++) {
                ret = rc_write_cfg(qrc, &d->cfg_ramp_en[i], RC_DCVS_CFG_SID, 1);
                if (ret)
                        return ret;
        }

        return 0;
}

/**
 * qcom_ramp_controller_start() - Initialize and start the ramp controller
 * @qrc: Main driver structure
 *
 * The Ramp Controller needs to be initialized by programming the relevant
 * registers with SoC-specific configuration: once programming is done,
 * the hardware will take care of the rest (no further handling required).
 *
 * Return: Zero for success or negative number for error
 */
static int qcom_ramp_controller_start(struct qcom_ramp_controller *qrc)
{
        const struct qcom_ramp_controller_desc *d = qrc->desc;
        int ret;

        /* Program LMH, DFS, Link SIDs */
        ret = rc_write_cfg(qrc, d->cfg_lmh_sid, RC_LMH_SID, d->num_lmh_sids);
        if (ret)
                return ret;

        ret = rc_write_cfg(qrc, d->cfg_dfs_sid, RC_DFS_SID, d->num_dfs_sids);
        if (ret)
                return ret;

        ret = rc_write_cfg(qrc, d->cfg_link_sid, RC_LINK_SID, d->num_link_sids);
        if (ret)
                return ret;

        /* Everything is ready! Enable the ramp up/down control */
        return rc_ramp_ctrl_enable(qrc);
}

static const struct regmap_config qrc_regmap_config = {
        .reg_bits = 32,
        .reg_stride = 4,
        .val_bits = 32,
        .max_register = 0x68,
};

static const struct reg_sequence msm8976_cfg_dfs_sid[] = {
        { 0x10, 0xfefebff7 },
        { 0x14, 0xfdff7fef },
        { 0x18, 0xfbffdefb },
        { 0x1c, 0xb69b5555 },
        { 0x20, 0x24929249 },
        { 0x24, 0x49241112 },
        { 0x28, 0x11112111 },
        { 0x2c, 0x8102 }
};

static const struct reg_sequence msm8976_cfg_link_sid[] = {
        { 0x40, 0xfc987 }
};

static const struct reg_sequence msm8976_cfg_lmh_sid[] = {
        { 0x30, 0x77706db },
        { 0x34, 0x5550249 },
        { 0x38, 0x111 }
};

static const struct reg_sequence msm8976_cfg_ramp_en[] = {
        { 0x50, 0x800 }, /* pre_en */
        { 0x50, 0xc00 }, /* en */
        { 0x50, 0x400 }  /* post_en */
};

static const struct reg_sequence msm8976_cfg_ramp_dis[] = {
        { 0x50, 0x0 }
};

static const struct qcom_ramp_controller_desc msm8976_rc_cfg = {
        .cfg_dfs_sid = msm8976_cfg_dfs_sid,
        .num_dfs_sids = ARRAY_SIZE(msm8976_cfg_dfs_sid),

        .cfg_link_sid = msm8976_cfg_link_sid,
        .num_link_sids = ARRAY_SIZE(msm8976_cfg_link_sid),

        .cfg_lmh_sid = msm8976_cfg_lmh_sid,
        .num_lmh_sids = ARRAY_SIZE(msm8976_cfg_lmh_sid),

        .cfg_ramp_en = msm8976_cfg_ramp_en,
        .num_ramp_en = ARRAY_SIZE(msm8976_cfg_ramp_en),

        .cfg_ramp_dis = msm8976_cfg_ramp_dis,
        .num_ramp_dis = ARRAY_SIZE(msm8976_cfg_ramp_dis),

        .cmd_reg = 0x0,
};

static int qcom_ramp_controller_probe(struct platform_device *pdev)
{
        struct qcom_ramp_controller *qrc;
        void __iomem *base;

        base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(base))
                return PTR_ERR(base);

        qrc = devm_kmalloc(&pdev->dev, sizeof(*qrc), GFP_KERNEL);
        if (!qrc)
                return -ENOMEM;

        qrc->desc = device_get_match_data(&pdev->dev);
        if (!qrc->desc)
                return -EINVAL;

        qrc->regmap = devm_regmap_init_mmio(&pdev->dev, base, &qrc_regmap_config);
        if (IS_ERR(qrc->regmap))
                return PTR_ERR(qrc->regmap);

        platform_set_drvdata(pdev, qrc);

        return qcom_ramp_controller_start(qrc);
}

static void qcom_ramp_controller_remove(struct platform_device *pdev)
{
        struct qcom_ramp_controller *qrc = platform_get_drvdata(pdev);
        int ret;

        ret = rc_write_cfg(qrc, qrc->desc->cfg_ramp_dis,
                           RC_DCVS_CFG_SID, qrc->desc->num_ramp_dis);
        if (ret)
                dev_err(&pdev->dev, "Failed to send disable sequence\n");
}

static const struct of_device_id qcom_ramp_controller_match_table[] = {
        { .compatible = "qcom,msm8976-ramp-controller", .data = &msm8976_rc_cfg },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, qcom_ramp_controller_match_table);

static struct platform_driver qcom_ramp_controller_driver = {
        .driver = {
                .name = "qcom-ramp-controller",
                .of_match_table = qcom_ramp_controller_match_table,
                .suppress_bind_attrs = true,
        },
        .probe = qcom_ramp_controller_probe,
        .remove = qcom_ramp_controller_remove,
};

static int __init qcom_ramp_controller_init(void)
{
        return platform_driver_register(&qcom_ramp_controller_driver);
}
arch_initcall(qcom_ramp_controller_init);

MODULE_AUTHOR("AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>");
MODULE_DESCRIPTION("Qualcomm Ramp Controller driver");
MODULE_LICENSE("GPL");