// SPDX-License-Identifier: GPL-2.0
/*
 * STM32 Low-Power Timer parent driver.
 * Copyright (C) STMicroelectronics 2017
 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
 * Inspired by Benjamin Gaignard's stm32-timers driver
 */

#include <linux/bitfield.h>
#include <linux/mfd/stm32-lptimer.h>
#include <linux/module.h>
#include <linux/of_platform.h>
#include <linux/platform_device.h>

#define STM32_LPTIM_MAX_REGISTER        0x3fc

static const struct regmap_config stm32_lptimer_regmap_cfg = {
        .reg_bits = 32,
        .val_bits = 32,
        .reg_stride = sizeof(u32),
        .max_register = STM32_LPTIM_MAX_REGISTER,
};

static int stm32_lptimer_detect_encoder(struct stm32_lptimer *ddata)
{
        u32 val;
        int ret;

        /*
         * Quadrature encoder mode bit can only be written and read back when
         * Low-Power Timer supports it.
         */
        ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
                                 STM32_LPTIM_ENC, STM32_LPTIM_ENC);
        if (ret)
                return ret;

        ret = regmap_read(ddata->regmap, STM32_LPTIM_CFGR, &val);
        if (ret)
                return ret;

        ret = regmap_update_bits(ddata->regmap, STM32_LPTIM_CFGR,
                                 STM32_LPTIM_ENC, 0);
        if (ret)
                return ret;

        ddata->has_encoder = !!(val & STM32_LPTIM_ENC);

        return 0;
}

static int stm32_lptimer_detect_hwcfgr(struct stm32_lptimer *ddata)
{
        u32 val;
        int ret;

        ret = regmap_read(ddata->regmap, STM32_LPTIM_VERR, &ddata->version);
        if (ret)
                return ret;

        /* Try to guess parameters from HWCFGR: e.g. encoder mode (STM32MP15) */
        ret = regmap_read(ddata->regmap, STM32_LPTIM_HWCFGR1, &val);
        if (ret)
                return ret;

        /* Fallback to legacy init if HWCFGR isn't present */
        if (!val)
                return stm32_lptimer_detect_encoder(ddata);

        ddata->has_encoder = FIELD_GET(STM32_LPTIM_HWCFGR1_ENCODER, val);

        ret = regmap_read(ddata->regmap, STM32_LPTIM_HWCFGR2, &val);
        if (ret)
                return ret;

        /* Number of capture/compare channels */
        ddata->num_cc_chans = FIELD_GET(STM32_LPTIM_HWCFGR2_CHAN_NUM, val);

        return 0;
}

static int stm32_lptimer_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct stm32_lptimer *ddata;
        void __iomem *mmio;
        int ret;

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

        mmio = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
        if (IS_ERR(mmio))
                return PTR_ERR(mmio);

        ddata->regmap = devm_regmap_init_mmio_clk(dev, "mux", mmio,
                                                  &stm32_lptimer_regmap_cfg);
        if (IS_ERR(ddata->regmap))
                return PTR_ERR(ddata->regmap);

        ddata->clk = devm_clk_get(dev, NULL);
        if (IS_ERR(ddata->clk))
                return PTR_ERR(ddata->clk);

        ret = stm32_lptimer_detect_hwcfgr(ddata);
        if (ret)
                return ret;

        platform_set_drvdata(pdev, ddata);

        return devm_of_platform_populate(&pdev->dev);
}

static const struct of_device_id stm32_lptimer_of_match[] = {
        { .compatible = "st,stm32-lptimer", },
        {},
};
MODULE_DEVICE_TABLE(of, stm32_lptimer_of_match);

static struct platform_driver stm32_lptimer_driver = {
        .probe = stm32_lptimer_probe,
        .driver = {
                .name = "stm32-lptimer",
                .of_match_table = stm32_lptimer_of_match,
        },
};
module_platform_driver(stm32_lptimer_driver);

MODULE_AUTHOR("Fabrice Gasnier <fabrice.gasnier@st.com>");
MODULE_DESCRIPTION("STMicroelectronics STM32 Low-Power Timer");
MODULE_ALIAS("platform:stm32-lptimer");
MODULE_LICENSE("GPL v2");