// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2018, STMicroelectronics - All Rights Reserved
 * Author: Fabrice Gasnier <fabrice.gasnier@st.com>
 *
 * Originally based on the Linux kernel v4.18 drivers/iio/adc/stm32-adc-core.c.
 */

#include <common.h>
#include <asm/io.h>
#include <power/regulator.h>
#include "stm32-adc-core.h"

/* STM32H7 - common registers for all ADC instances */
#define STM32H7_ADC_CCR                 (STM32_ADCX_COMN_OFFSET + 0x08)

/* STM32H7_ADC_CCR - bit fields */
#define STM32H7_PRESC_SHIFT             18
#define STM32H7_PRESC_MASK              GENMASK(21, 18)
#define STM32H7_CKMODE_SHIFT            16
#define STM32H7_CKMODE_MASK             GENMASK(17, 16)

/* STM32 H7 maximum analog clock rate (from datasheet) */
#define STM32H7_ADC_MAX_CLK_RATE        36000000

/**
 * struct stm32h7_adc_ck_spec - specification for stm32h7 adc clock
 * @ckmode: ADC clock mode, Async or sync with prescaler.
 * @presc: prescaler bitfield for async clock mode
 * @div: prescaler division ratio
 */
struct stm32h7_adc_ck_spec {
        u32 ckmode;
        u32 presc;
        int div;
};

static const struct stm32h7_adc_ck_spec stm32h7_adc_ckmodes_spec[] = {
        /* 00: CK_ADC[1..3]: Asynchronous clock modes */
        { 0, 0, 1 },
        { 0, 1, 2 },
        { 0, 2, 4 },
        { 0, 3, 6 },
        { 0, 4, 8 },
        { 0, 5, 10 },
        { 0, 6, 12 },
        { 0, 7, 16 },
        { 0, 8, 32 },
        { 0, 9, 64 },
        { 0, 10, 128 },
        { 0, 11, 256 },
        /* HCLK used: Synchronous clock modes (1, 2 or 4 prescaler) */
        { 1, 0, 1 },
        { 2, 0, 2 },
        { 3, 0, 4 },
};

static int stm32h7_adc_clk_sel(struct udevice *dev,
                               struct stm32_adc_common *common)
{
        u32 ckmode, presc;
        unsigned long rate;
        int i, div;

        /* stm32h7 bus clock is common for all ADC instances (mandatory) */
        if (!clk_valid(&common->bclk)) {
                dev_err(dev, "No bclk clock found\n");
                return -ENOENT;
        }

        /*
         * stm32h7 can use either 'bus' or 'adc' clock for analog circuitry.
         * So, choice is to have bus clock mandatory and adc clock optional.
         * If optional 'adc' clock has been found, then try to use it first.
         */
        if (clk_valid(&common->aclk)) {
                /*
                 * Asynchronous clock modes (e.g. ckmode == 0)
                 * From spec: PLL output musn't exceed max rate
                 */
                rate = clk_get_rate(&common->aclk);
                if (!rate) {
                        dev_err(dev, "Invalid aclk rate: 0\n");
                        return -EINVAL;
                }

                for (i = 0; i < ARRAY_SIZE(stm32h7_adc_ckmodes_spec); i++) {
                        ckmode = stm32h7_adc_ckmodes_spec[i].ckmode;
                        presc = stm32h7_adc_ckmodes_spec[i].presc;
                        div = stm32h7_adc_ckmodes_spec[i].div;

                        if (ckmode)
                                continue;

                        if ((rate / div) <= STM32H7_ADC_MAX_CLK_RATE)
                                goto out;
                }
        }

        /* Synchronous clock modes (e.g. ckmode is 1, 2 or 3) */
        rate = clk_get_rate(&common->bclk);
        if (!rate) {
                dev_err(dev, "Invalid bus clock rate: 0\n");
                return -EINVAL;
        }

        for (i = 0; i < ARRAY_SIZE(stm32h7_adc_ckmodes_spec); i++) {
                ckmode = stm32h7_adc_ckmodes_spec[i].ckmode;
                presc = stm32h7_adc_ckmodes_spec[i].presc;
                div = stm32h7_adc_ckmodes_spec[i].div;

                if (!ckmode)
                        continue;

                if ((rate / div) <= STM32H7_ADC_MAX_CLK_RATE)
                        goto out;
        }

        dev_err(dev, "clk selection failed\n");
        return -EINVAL;

out:
        /* rate used later by each ADC instance to control BOOST mode */
        common->rate = rate / div;

        /* Set common clock mode and prescaler */
        clrsetbits_le32(common->base + STM32H7_ADC_CCR,
                        STM32H7_CKMODE_MASK | STM32H7_PRESC_MASK,
                        ckmode << STM32H7_CKMODE_SHIFT |
                        presc << STM32H7_PRESC_SHIFT);

        dev_dbg(dev, "Using %s clock/%d source at %ld kHz\n",
                ckmode ? "bus" : "adc", div, common->rate / 1000);

        return 0;
}

static int stm32_adc_core_probe(struct udevice *dev)
{
        struct stm32_adc_common *common = dev_get_priv(dev);
        int ret;

        common->base = dev_read_addr_ptr(dev);
        if (!common->base) {
                dev_err(dev, "can't get address\n");
                return -ENOENT;
        }

        ret = device_get_supply_regulator(dev, "vref-supply", &common->vref);
        if (ret) {
                dev_err(dev, "can't get vref-supply: %d\n", ret);
                return ret;
        }

        ret = regulator_get_value(common->vref);
        if (ret < 0) {
                dev_err(dev, "can't get vref-supply value: %d\n", ret);
                return ret;
        }
        common->vref_uv = ret;

        ret = clk_get_by_name(dev, "adc", &common->aclk);
        if (!ret) {
                ret = clk_enable(&common->aclk);
                if (ret) {
                        dev_err(dev, "Can't enable aclk: %d\n", ret);
                        return ret;
                }
        }

        ret = clk_get_by_name(dev, "bus", &common->bclk);
        if (!ret) {
                ret = clk_enable(&common->bclk);
                if (ret) {
                        dev_err(dev, "Can't enable bclk: %d\n", ret);
                        goto err_aclk_disable;
                }
        }

        ret = stm32h7_adc_clk_sel(dev, common);
        if (ret)
                goto err_bclk_disable;

        return ret;

err_bclk_disable:
        if (clk_valid(&common->bclk))
                clk_disable(&common->bclk);

err_aclk_disable:
        if (clk_valid(&common->aclk))
                clk_disable(&common->aclk);

        return ret;
}

static const struct udevice_id stm32_adc_core_ids[] = {
        { .compatible = "st,stm32h7-adc-core" },
        { .compatible = "st,stm32mp1-adc-core" },
        {}
};

U_BOOT_DRIVER(stm32_adc_core) = {
        .name  = "stm32-adc-core",
        .id = UCLASS_SIMPLE_BUS,
        .of_match = stm32_adc_core_ids,
        .probe = stm32_adc_core_probe,
        .priv_auto_alloc_size = sizeof(struct stm32_adc_common),
};