// SPDX-License-Identifier: GPL-2.0+
/*
 * Copyright (C) 2012 Michal Simek <monstr@monstr.eu>
 * Copyright (C) 2011-2012 Xilinx, Inc. All rights reserved.
 */

#include <clk.h>
#include <common.h>
#include <debug_uart.h>
#include <dm.h>
#include <errno.h>
#include <fdtdec.h>
#include <log.h>
#include <watchdog.h>
#include <asm/io.h>
#include <dm/device_compat.h>
#include <linux/bitops.h>
#include <linux/compiler.h>
#include <serial.h>
#include <linux/err.h>

#define ZYNQ_UART_SR_TXACTIVE   BIT(11) /* TX active */
#define ZYNQ_UART_SR_TXFULL     BIT(4) /* TX FIFO full */
#define ZYNQ_UART_SR_RXEMPTY    BIT(1) /* RX FIFO empty */

#define ZYNQ_UART_CR_TX_EN      BIT(4) /* TX enabled */
#define ZYNQ_UART_CR_RX_EN      BIT(2) /* RX enabled */
#define ZYNQ_UART_CR_TXRST      BIT(1) /* TX logic reset */
#define ZYNQ_UART_CR_RXRST      BIT(0) /* RX logic reset */

#define ZYNQ_UART_MR_PARITY_NONE        0x00000020  /* No parity mode */

struct uart_zynq {
        u32 control; /* 0x0 - Control Register [8:0] */
        u32 mode; /* 0x4 - Mode Register [10:0] */
        u32 reserved1[4];
        u32 baud_rate_gen; /* 0x18 - Baud Rate Generator [15:0] */
        u32 reserved2[4];
        u32 channel_sts; /* 0x2c - Channel Status [11:0] */
        u32 tx_rx_fifo; /* 0x30 - FIFO [15:0] or [7:0] */
        u32 baud_rate_divider; /* 0x34 - Baud Rate Divider [7:0] */
};

struct zynq_uart_platdata {
        struct uart_zynq *regs;
};

/* Set up the baud rate */
static void _uart_zynq_serial_setbrg(struct uart_zynq *regs,
                                     unsigned long clock, unsigned long baud)
{
        /* Calculation results. */
        unsigned int calc_bauderror, bdiv, bgen;
        unsigned long calc_baud = 0;

        /* Covering case where input clock is so slow */
        if (clock < 1000000 && baud > 4800)
                baud = 4800;

        /*                master clock
         * Baud rate = ------------------
         *              bgen * (bdiv + 1)
         *
         * Find acceptable values for baud generation.
         */
        for (bdiv = 4; bdiv < 255; bdiv++) {
                bgen = clock / (baud * (bdiv + 1));
                if (bgen < 2 || bgen > 65535)
                        continue;

                calc_baud = clock / (bgen * (bdiv + 1));

                /*
                 * Use first calculated baudrate with
                 * an acceptable (<3%) error
                 */
                if (baud > calc_baud)
                        calc_bauderror = baud - calc_baud;
                else
                        calc_bauderror = calc_baud - baud;
                if (((calc_bauderror * 100) / baud) < 3)
                        break;
        }

        writel(bdiv, &regs->baud_rate_divider);
        writel(bgen, &regs->baud_rate_gen);
}

/* Initialize the UART, with...some settings. */
static void _uart_zynq_serial_init(struct uart_zynq *regs)
{
        /* RX/TX enabled & reset */
        writel(ZYNQ_UART_CR_TX_EN | ZYNQ_UART_CR_RX_EN | ZYNQ_UART_CR_TXRST | \
                                        ZYNQ_UART_CR_RXRST, &regs->control);
        writel(ZYNQ_UART_MR_PARITY_NONE, &regs->mode); /* 8 bit, no parity */
}

static int _uart_zynq_serial_putc(struct uart_zynq *regs, const char c)
{
        if (readl(&regs->channel_sts) & ZYNQ_UART_SR_TXFULL)
                return -EAGAIN;

        writel(c, &regs->tx_rx_fifo);

        return 0;
}

static int zynq_serial_setbrg(struct udevice *dev, int baudrate)
{
        struct zynq_uart_platdata *platdata = dev_get_platdata(dev);
        unsigned long clock;

        int ret;
        struct clk clk;

        ret = clk_get_by_index(dev, 0, &clk);
        if (ret < 0) {
                dev_err(dev, "failed to get clock\n");
                return ret;
        }

        clock = clk_get_rate(&clk);
        if (IS_ERR_VALUE(clock)) {
                dev_err(dev, "failed to get rate\n");
                return clock;
        }
        debug("%s: CLK %ld\n", __func__, clock);

        ret = clk_enable(&clk);
        if (ret && ret != -ENOSYS) {
                dev_err(dev, "failed to enable clock\n");
                return ret;
        }

        _uart_zynq_serial_setbrg(platdata->regs, clock, baudrate);

        return 0;
}

static int zynq_serial_probe(struct udevice *dev)
{
        struct zynq_uart_platdata *platdata = dev_get_platdata(dev);
        struct uart_zynq *regs = platdata->regs;
        u32 val;

        /* No need to reinitialize the UART if TX already enabled */
        val = readl(&regs->control);
        if (val & ZYNQ_UART_CR_TX_EN)
                return 0;

        _uart_zynq_serial_init(platdata->regs);

        return 0;
}

static int zynq_serial_getc(struct udevice *dev)
{
        struct zynq_uart_platdata *platdata = dev_get_platdata(dev);
        struct uart_zynq *regs = platdata->regs;

        if (readl(&regs->channel_sts) & ZYNQ_UART_SR_RXEMPTY)
                return -EAGAIN;

        return readl(&regs->tx_rx_fifo);
}

static int zynq_serial_putc(struct udevice *dev, const char ch)
{
        struct zynq_uart_platdata *platdata = dev_get_platdata(dev);

        return _uart_zynq_serial_putc(platdata->regs, ch);
}

static int zynq_serial_pending(struct udevice *dev, bool input)
{
        struct zynq_uart_platdata *platdata = dev_get_platdata(dev);
        struct uart_zynq *regs = platdata->regs;

        if (input)
                return !(readl(&regs->channel_sts) & ZYNQ_UART_SR_RXEMPTY);
        else
                return !!(readl(&regs->channel_sts) & ZYNQ_UART_SR_TXACTIVE);
}

static int zynq_serial_ofdata_to_platdata(struct udevice *dev)
{
        struct zynq_uart_platdata *platdata = dev_get_platdata(dev);

        platdata->regs = (struct uart_zynq *)dev_read_addr(dev);
        if (IS_ERR(platdata->regs))
                return PTR_ERR(platdata->regs);

        return 0;
}

static const struct dm_serial_ops zynq_serial_ops = {
        .putc = zynq_serial_putc,
        .pending = zynq_serial_pending,
        .getc = zynq_serial_getc,
        .setbrg = zynq_serial_setbrg,
};

static const struct udevice_id zynq_serial_ids[] = {
        { .compatible = "xlnx,xuartps" },
        { .compatible = "cdns,uart-r1p8" },
        { .compatible = "cdns,uart-r1p12" },
        { }
};

U_BOOT_DRIVER(serial_zynq) = {
        .name   = "serial_zynq",
        .id     = UCLASS_SERIAL,
        .of_match = zynq_serial_ids,
        .ofdata_to_platdata = zynq_serial_ofdata_to_platdata,
        .platdata_auto_alloc_size = sizeof(struct zynq_uart_platdata),
        .probe = zynq_serial_probe,
        .ops    = &zynq_serial_ops,
};

#ifdef CONFIG_DEBUG_UART_ZYNQ
static inline void _debug_uart_init(void)
{
        struct uart_zynq *regs = (struct uart_zynq *)CONFIG_DEBUG_UART_BASE;

        _uart_zynq_serial_init(regs);
        _uart_zynq_serial_setbrg(regs, CONFIG_DEBUG_UART_CLOCK,
                                 CONFIG_BAUDRATE);
}

static inline void _debug_uart_putc(int ch)
{
        struct uart_zynq *regs = (struct uart_zynq *)CONFIG_DEBUG_UART_BASE;

        while (_uart_zynq_serial_putc(regs, ch) == -EAGAIN)
                WATCHDOG_RESET();
}

DEBUG_UART_FUNCS

#endif