// SPDX-License-Identifier: GPL-2.0-only
/* Copyright (c) 2013, The Linux Foundation. All rights reserved.
 * Copyright (c) 2015, Sony Mobile Communications Inc.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/regmap.h>
#include <linux/platform_device.h>

struct qcom_coincell {
        struct device   *dev;
        struct regmap   *regmap;
        u32             base_addr;
};

#define QCOM_COINCELL_REG_RSET          0x44
#define QCOM_COINCELL_REG_VSET          0x45
#define QCOM_COINCELL_REG_ENABLE        0x46

#define QCOM_COINCELL_ENABLE            BIT(7)

static const int qcom_rset_map[] = { 2100, 1700, 1200, 800 };
static const int qcom_vset_map[] = { 2500, 3200, 3100, 3000 };
/* NOTE: for pm8921 and others, voltage of 2500 is 16 (10000b), not 0 */

/* if enable==0, rset and vset are ignored */
static int qcom_coincell_chgr_config(struct qcom_coincell *chgr, int rset,
                                     int vset, bool enable)
{
        int i, j, rc;

        /* if disabling, just do that and skip other operations */
        if (!enable)
                return regmap_write(chgr->regmap,
                          chgr->base_addr + QCOM_COINCELL_REG_ENABLE, 0);

        /* find index for current-limiting resistor */
        for (i = 0; i < ARRAY_SIZE(qcom_rset_map); i++)
                if (rset == qcom_rset_map[i])
                        break;

        if (i >= ARRAY_SIZE(qcom_rset_map)) {
                dev_err(chgr->dev, "invalid rset-ohms value %d\n", rset);
                return -EINVAL;
        }

        /* find index for charge voltage */
        for (j = 0; j < ARRAY_SIZE(qcom_vset_map); j++)
                if (vset == qcom_vset_map[j])
                        break;

        if (j >= ARRAY_SIZE(qcom_vset_map)) {
                dev_err(chgr->dev, "invalid vset-millivolts value %d\n", vset);
                return -EINVAL;
        }

        rc = regmap_write(chgr->regmap,
                          chgr->base_addr + QCOM_COINCELL_REG_RSET, i);
        if (rc) {
                /*
                 * This is mainly to flag a bad base_addr (reg) from dts.
                 * Other failures writing to the registers should be
                 * extremely rare, or indicative of problems that
                 * should be reported elsewhere (eg. spmi failure).
                 */
                dev_err(chgr->dev, "could not write to RSET register\n");
                return rc;
        }

        rc = regmap_write(chgr->regmap,
                chgr->base_addr + QCOM_COINCELL_REG_VSET, j);
        if (rc)
                return rc;

        /* set 'enable' register */
        return regmap_write(chgr->regmap,
                            chgr->base_addr + QCOM_COINCELL_REG_ENABLE,
                            QCOM_COINCELL_ENABLE);
}

static int qcom_coincell_probe(struct platform_device *pdev)
{
        struct device_node *node = pdev->dev.of_node;
        struct qcom_coincell chgr;
        u32 rset = 0;
        u32 vset = 0;
        bool enable;
        int rc;

        chgr.dev = &pdev->dev;

        chgr.regmap = dev_get_regmap(pdev->dev.parent, NULL);
        if (!chgr.regmap) {
                dev_err(chgr.dev, "Unable to get regmap\n");
                return -EINVAL;
        }

        rc = of_property_read_u32(node, "reg", &chgr.base_addr);
        if (rc)
                return rc;

        enable = !of_property_read_bool(node, "qcom,charger-disable");

        if (enable) {
                rc = of_property_read_u32(node, "qcom,rset-ohms", &rset);
                if (rc) {
                        dev_err(chgr.dev,
                                "can't find 'qcom,rset-ohms' in DT block");
                        return rc;
                }

                rc = of_property_read_u32(node, "qcom,vset-millivolts", &vset);
                if (rc) {
                        dev_err(chgr.dev,
                            "can't find 'qcom,vset-millivolts' in DT block");
                        return rc;
                }
        }

        return qcom_coincell_chgr_config(&chgr, rset, vset, enable);
}

static const struct of_device_id qcom_coincell_match_table[] = {
        { .compatible = "qcom,pm8941-coincell", },
        {}
};

MODULE_DEVICE_TABLE(of, qcom_coincell_match_table);

static struct platform_driver qcom_coincell_driver = {
        .driver = {
                .name           = "qcom-spmi-coincell",
                .of_match_table = qcom_coincell_match_table,
        },
        .probe          = qcom_coincell_probe,
};

module_platform_driver(qcom_coincell_driver);

MODULE_DESCRIPTION("Qualcomm PMIC coincell charger driver");
MODULE_LICENSE("GPL v2");