// SPDX-License-Identifier: GPL-2.0
/*
 * serial_tegra.c
 *
 * High-speed serial driver for NVIDIA Tegra SoCs
 *
 * Copyright (c) 2012-2019, NVIDIA CORPORATION.  All rights reserved.
 *
 * Author: Laxman Dewangan <ldewangan@nvidia.com>
 */

#include <linux/clk.h>
#include <linux/debugfs.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dmapool.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pagemap.h>
#include <linux/platform_device.h>
#include <linux/reset.h>
#include <linux/serial.h>
#include <linux/serial_8250.h>
#include <linux/serial_core.h>
#include <linux/serial_reg.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/termios.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>

#define TEGRA_UART_TYPE                         "TEGRA_UART"
#define TX_EMPTY_STATUS                         (UART_LSR_TEMT | UART_LSR_THRE)
#define BYTES_TO_ALIGN(x)                       ((unsigned long)(x) & 0x3)

#define TEGRA_UART_RX_DMA_BUFFER_SIZE           4096
#define TEGRA_UART_LSR_TXFIFO_FULL              0x100
#define TEGRA_UART_IER_EORD                     0x20
#define TEGRA_UART_MCR_RTS_EN                   0x40
#define TEGRA_UART_MCR_CTS_EN                   0x20
#define TEGRA_UART_LSR_ANY                      (UART_LSR_OE | UART_LSR_BI | \
                                                UART_LSR_PE | UART_LSR_FE)
#define TEGRA_UART_IRDA_CSR                     0x08
#define TEGRA_UART_SIR_ENABLED                  0x80

#define TEGRA_UART_TX_PIO                       1
#define TEGRA_UART_TX_DMA                       2
#define TEGRA_UART_MIN_DMA                      16
#define TEGRA_UART_FIFO_SIZE                    32

/*
 * Tx fifo trigger level setting in tegra uart is in
 * reverse way then conventional uart.
 */
#define TEGRA_UART_TX_TRIG_16B                  0x00
#define TEGRA_UART_TX_TRIG_8B                   0x10
#define TEGRA_UART_TX_TRIG_4B                   0x20
#define TEGRA_UART_TX_TRIG_1B                   0x30

#define TEGRA_UART_MAXIMUM                      8

/* Default UART setting when started: 115200 no parity, stop, 8 data bits */
#define TEGRA_UART_DEFAULT_BAUD                 115200
#define TEGRA_UART_DEFAULT_LSR                  UART_LCR_WLEN8

/* Tx transfer mode */
#define TEGRA_TX_PIO                            1
#define TEGRA_TX_DMA                            2

#define TEGRA_UART_FCR_IIR_FIFO_EN              0x40

/**
 * struct tegra_uart_chip_data: SOC specific data.
 *
 * @tx_fifo_full_status: Status flag available for checking tx fifo full.
 * @allow_txfifo_reset_fifo_mode: allow_tx fifo reset with fifo mode or not.
 *                      Tegra30 does not allow this.
 * @support_clk_src_div: Clock source support the clock divider.
 * @fifo_mode_enable_status: Is FIFO mode enabled?
 * @uart_max_port: Maximum number of UART ports
 * @max_dma_burst_bytes: Maximum size of DMA bursts
 * @error_tolerance_low_range: Lowest number in the error tolerance range
 * @error_tolerance_high_range: Highest number in the error tolerance range
 */
struct tegra_uart_chip_data {
        bool    tx_fifo_full_status;
        bool    allow_txfifo_reset_fifo_mode;
        bool    support_clk_src_div;
        bool    fifo_mode_enable_status;
        int     uart_max_port;
        int     max_dma_burst_bytes;
        int     error_tolerance_low_range;
        int     error_tolerance_high_range;
};

struct tegra_baud_tolerance {
        u32 lower_range_baud;
        u32 upper_range_baud;
        s32 tolerance;
};

struct tegra_uart_port {
        struct uart_port                        uport;
        const struct tegra_uart_chip_data       *cdata;

        struct clk                              *uart_clk;
        struct reset_control                    *rst;
        unsigned int                            current_baud;

        /* Register shadow */
        unsigned long                           fcr_shadow;
        unsigned long                           mcr_shadow;
        unsigned long                           lcr_shadow;
        unsigned long                           ier_shadow;
        bool                                    rts_active;

        int                                     tx_in_progress;
        unsigned int                            tx_bytes;

        bool                                    enable_modem_interrupt;

        bool                                    rx_timeout;
        int                                     rx_in_progress;
        int                                     symb_bit;

        struct dma_chan                         *rx_dma_chan;
        struct dma_chan                         *tx_dma_chan;
        dma_addr_t                              rx_dma_buf_phys;
        dma_addr_t                              tx_dma_buf_phys;
        unsigned char                           *rx_dma_buf_virt;
        unsigned char                           *tx_dma_buf_virt;
        struct dma_async_tx_descriptor          *tx_dma_desc;
        struct dma_async_tx_descriptor          *rx_dma_desc;
        dma_cookie_t                            tx_cookie;
        dma_cookie_t                            rx_cookie;
        unsigned int                            tx_bytes_requested;
        unsigned int                            rx_bytes_requested;
        struct tegra_baud_tolerance             *baud_tolerance;
        int                                     n_adjustable_baud_rates;
        int                                     required_rate;
        int                                     configured_rate;
        bool                                    use_rx_pio;
        bool                                    use_tx_pio;
        bool                                    rx_dma_active;
};

static void tegra_uart_start_next_tx(struct tegra_uart_port *tup);
static int tegra_uart_start_rx_dma(struct tegra_uart_port *tup);
static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,
                                        bool dma_to_memory);

static inline unsigned long tegra_uart_read(struct tegra_uart_port *tup,
                unsigned long reg)
{
        return readl(tup->uport.membase + (reg << tup->uport.regshift));
}

static inline void tegra_uart_write(struct tegra_uart_port *tup, unsigned val,
        unsigned long reg)
{
        writel(val, tup->uport.membase + (reg << tup->uport.regshift));
}

static inline struct tegra_uart_port *to_tegra_uport(struct uart_port *u)
{
        return container_of(u, struct tegra_uart_port, uport);
}

static unsigned int tegra_uart_get_mctrl(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);

        /*
         * RI - Ring detector is active
         * CD/DCD/CAR - Carrier detect is always active. For some reason
         *      linux has different names for carrier detect.
         * DSR - Data Set ready is active as the hardware doesn't support it.
         *      Don't know if the linux support this yet?
         * CTS - Clear to send. Always set to active, as the hardware handles
         *      CTS automatically.
         */
        if (tup->enable_modem_interrupt)
                return TIOCM_RI | TIOCM_CD | TIOCM_DSR | TIOCM_CTS;
        return TIOCM_CTS;
}

static void set_rts(struct tegra_uart_port *tup, bool active)
{
        unsigned long mcr;

        mcr = tup->mcr_shadow;
        if (active)
                mcr |= TEGRA_UART_MCR_RTS_EN;
        else
                mcr &= ~TEGRA_UART_MCR_RTS_EN;
        if (mcr != tup->mcr_shadow) {
                tegra_uart_write(tup, mcr, UART_MCR);
                tup->mcr_shadow = mcr;
        }
}

static void set_dtr(struct tegra_uart_port *tup, bool active)
{
        unsigned long mcr;

        mcr = tup->mcr_shadow;
        if (active)
                mcr |= UART_MCR_DTR;
        else
                mcr &= ~UART_MCR_DTR;
        if (mcr != tup->mcr_shadow) {
                tegra_uart_write(tup, mcr, UART_MCR);
                tup->mcr_shadow = mcr;
        }
}

static void set_loopbk(struct tegra_uart_port *tup, bool active)
{
        unsigned long mcr = tup->mcr_shadow;

        if (active)
                mcr |= UART_MCR_LOOP;
        else
                mcr &= ~UART_MCR_LOOP;

        if (mcr != tup->mcr_shadow) {
                tegra_uart_write(tup, mcr, UART_MCR);
                tup->mcr_shadow = mcr;
        }
}

static void tegra_uart_set_mctrl(struct uart_port *u, unsigned int mctrl)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        int enable;

        tup->rts_active = !!(mctrl & TIOCM_RTS);
        set_rts(tup, tup->rts_active);

        enable = !!(mctrl & TIOCM_DTR);
        set_dtr(tup, enable);

        enable = !!(mctrl & TIOCM_LOOP);
        set_loopbk(tup, enable);
}

static void tegra_uart_break_ctl(struct uart_port *u, int break_ctl)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        unsigned long lcr;

        lcr = tup->lcr_shadow;
        if (break_ctl)
                lcr |= UART_LCR_SBC;
        else
                lcr &= ~UART_LCR_SBC;
        tegra_uart_write(tup, lcr, UART_LCR);
        tup->lcr_shadow = lcr;
}

/**
 * tegra_uart_wait_cycle_time: Wait for N UART clock periods
 *
 * @tup:        Tegra serial port data structure.
 * @cycles:     Number of clock periods to wait.
 *
 * Tegra UARTs are clocked at 16X the baud/bit rate and hence the UART
 * clock speed is 16X the current baud rate.
 */
static void tegra_uart_wait_cycle_time(struct tegra_uart_port *tup,
                                       unsigned int cycles)
{
        if (tup->current_baud)
                udelay(DIV_ROUND_UP(cycles * 1000000, tup->current_baud * 16));
}

/* Wait for a symbol-time. */
static void tegra_uart_wait_sym_time(struct tegra_uart_port *tup,
                unsigned int syms)
{
        if (tup->current_baud)
                udelay(DIV_ROUND_UP(syms * tup->symb_bit * 1000000,
                        tup->current_baud));
}

static int tegra_uart_wait_fifo_mode_enabled(struct tegra_uart_port *tup)
{
        unsigned long iir;
        unsigned int tmout = 100;

        do {
                iir = tegra_uart_read(tup, UART_IIR);
                if (iir & TEGRA_UART_FCR_IIR_FIFO_EN)
                        return 0;
                udelay(1);
        } while (--tmout);

        return -ETIMEDOUT;
}

static void tegra_uart_fifo_reset(struct tegra_uart_port *tup, u8 fcr_bits)
{
        unsigned long fcr = tup->fcr_shadow;
        unsigned int lsr, tmout = 10000;

        if (tup->rts_active)
                set_rts(tup, false);

        if (tup->cdata->allow_txfifo_reset_fifo_mode) {
                fcr |= fcr_bits & (UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
                tegra_uart_write(tup, fcr, UART_FCR);
        } else {
                fcr &= ~UART_FCR_ENABLE_FIFO;
                tegra_uart_write(tup, fcr, UART_FCR);
                udelay(60);
                fcr |= fcr_bits & (UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT);
                tegra_uart_write(tup, fcr, UART_FCR);
                fcr |= UART_FCR_ENABLE_FIFO;
                tegra_uart_write(tup, fcr, UART_FCR);
                if (tup->cdata->fifo_mode_enable_status)
                        tegra_uart_wait_fifo_mode_enabled(tup);
        }

        /* Dummy read to ensure the write is posted */
        tegra_uart_read(tup, UART_SCR);

        /*
         * For all tegra devices (up to t210), there is a hardware issue that
         * requires software to wait for 32 UART clock periods for the flush
         * to propagate, otherwise data could be lost.
         */
        tegra_uart_wait_cycle_time(tup, 32);

        do {
                lsr = tegra_uart_read(tup, UART_LSR);
                if ((lsr & UART_LSR_TEMT) && !(lsr & UART_LSR_DR))
                        break;
                udelay(1);
        } while (--tmout);

        if (tup->rts_active)
                set_rts(tup, true);
}

static long tegra_get_tolerance_rate(struct tegra_uart_port *tup,
                                     unsigned int baud, long rate)
{
        int i;

        for (i = 0; i < tup->n_adjustable_baud_rates; ++i) {
                if (baud >= tup->baud_tolerance[i].lower_range_baud &&
                    baud <= tup->baud_tolerance[i].upper_range_baud)
                        return (rate + (rate *
                                tup->baud_tolerance[i].tolerance) / 10000);
        }

        return rate;
}

static int tegra_check_rate_in_range(struct tegra_uart_port *tup)
{
        long diff;

        diff = ((long)(tup->configured_rate - tup->required_rate) * 10000)
                / tup->required_rate;
        if (diff < (tup->cdata->error_tolerance_low_range * 100) ||
            diff > (tup->cdata->error_tolerance_high_range * 100)) {
                dev_err(tup->uport.dev,
                        "configured baud rate is out of range by %ld", diff);
                return -EIO;
        }

        return 0;
}

static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
{
        unsigned long rate;
        unsigned int divisor;
        unsigned long lcr;
        unsigned long flags;
        int ret;

        if (tup->current_baud == baud)
                return 0;

        if (tup->cdata->support_clk_src_div) {
                rate = baud * 16;
                tup->required_rate = rate;

                if (tup->n_adjustable_baud_rates)
                        rate = tegra_get_tolerance_rate(tup, baud, rate);

                ret = clk_set_rate(tup->uart_clk, rate);
                if (ret < 0) {
                        dev_err(tup->uport.dev,
                                "clk_set_rate() failed for rate %lu\n", rate);
                        return ret;
                }
                tup->configured_rate = clk_get_rate(tup->uart_clk);
                divisor = 1;
                ret = tegra_check_rate_in_range(tup);
                if (ret < 0)
                        return ret;
        } else {
                rate = clk_get_rate(tup->uart_clk);
                divisor = DIV_ROUND_CLOSEST(rate, baud * 16);
        }

        uart_port_lock_irqsave(&tup->uport, &flags);
        lcr = tup->lcr_shadow;
        lcr |= UART_LCR_DLAB;
        tegra_uart_write(tup, lcr, UART_LCR);

        tegra_uart_write(tup, divisor & 0xFF, UART_TX);
        tegra_uart_write(tup, ((divisor >> 8) & 0xFF), UART_IER);

        lcr &= ~UART_LCR_DLAB;
        tegra_uart_write(tup, lcr, UART_LCR);

        /* Dummy read to ensure the write is posted */
        tegra_uart_read(tup, UART_SCR);
        uart_port_unlock_irqrestore(&tup->uport, flags);

        tup->current_baud = baud;

        /* wait two character intervals at new rate */
        tegra_uart_wait_sym_time(tup, 2);
        return 0;
}

static u8 tegra_uart_decode_rx_error(struct tegra_uart_port *tup,
                        unsigned long lsr)
{
        u8 flag = TTY_NORMAL;

        if (unlikely(lsr & TEGRA_UART_LSR_ANY)) {
                if (lsr & UART_LSR_OE) {
                        /* Overrun error */
                        flag = TTY_OVERRUN;
                        tup->uport.icount.overrun++;
                        dev_dbg(tup->uport.dev, "Got overrun errors\n");
                } else if (lsr & UART_LSR_PE) {
                        /* Parity error */
                        flag = TTY_PARITY;
                        tup->uport.icount.parity++;
                        dev_dbg(tup->uport.dev, "Got Parity errors\n");
                } else if (lsr & UART_LSR_FE) {
                        flag = TTY_FRAME;
                        tup->uport.icount.frame++;
                        dev_dbg(tup->uport.dev, "Got frame errors\n");
                } else if (lsr & UART_LSR_BI) {
                        /*
                         * Break error
                         * If FIFO read error without any data, reset Rx FIFO
                         */
                        if (!(lsr & UART_LSR_DR) && (lsr & UART_LSR_FIFOE))
                                tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_RCVR);
                        if (tup->uport.ignore_status_mask & UART_LSR_BI)
                                return TTY_BREAK;
                        flag = TTY_BREAK;
                        tup->uport.icount.brk++;
                        dev_dbg(tup->uport.dev, "Got Break\n");
                }
                uart_insert_char(&tup->uport, lsr, UART_LSR_OE, 0, flag);
        }

        return flag;
}

static int tegra_uart_request_port(struct uart_port *u)
{
        return 0;
}

static void tegra_uart_release_port(struct uart_port *u)
{
        /* Nothing to do here */
}

static void tegra_uart_fill_tx_fifo(struct tegra_uart_port *tup, int max_bytes)
{
        unsigned char ch;
        int i;

        for (i = 0; i < max_bytes; i++) {
                if (tup->cdata->tx_fifo_full_status) {
                        unsigned long lsr = tegra_uart_read(tup, UART_LSR);
                        if ((lsr & TEGRA_UART_LSR_TXFIFO_FULL))
                                break;
                }
                if (WARN_ON_ONCE(!uart_fifo_get(&tup->uport, &ch)))
                        break;
                tegra_uart_write(tup, ch, UART_TX);
        }
}

static void tegra_uart_start_pio_tx(struct tegra_uart_port *tup,
                unsigned int bytes)
{
        if (bytes > TEGRA_UART_MIN_DMA)
                bytes = TEGRA_UART_MIN_DMA;

        tup->tx_in_progress = TEGRA_UART_TX_PIO;
        tup->tx_bytes = bytes;
        tup->ier_shadow |= UART_IER_THRI;
        tegra_uart_write(tup, tup->ier_shadow, UART_IER);
}

static void tegra_uart_tx_dma_complete(void *args)
{
        struct tegra_uart_port *tup = args;
        struct tty_port *tport = &tup->uport.state->port;
        struct dma_tx_state state;
        unsigned long flags;
        unsigned int count;

        dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
        count = tup->tx_bytes_requested - state.residue;
        async_tx_ack(tup->tx_dma_desc);
        uart_port_lock_irqsave(&tup->uport, &flags);
        uart_xmit_advance(&tup->uport, count);
        tup->tx_in_progress = 0;
        if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
                uart_write_wakeup(&tup->uport);
        tegra_uart_start_next_tx(tup);
        uart_port_unlock_irqrestore(&tup->uport, flags);
}

static int tegra_uart_start_tx_dma(struct tegra_uart_port *tup,
                unsigned long count)
{
        struct tty_port *tport = &tup->uport.state->port;
        dma_addr_t tx_phys_addr;
        unsigned int tail;

        tup->tx_bytes = count & ~(0xF);
        WARN_ON_ONCE(kfifo_out_linear(&tport->xmit_fifo, &tail,
                        UART_XMIT_SIZE) < count);
        tx_phys_addr = tup->tx_dma_buf_phys + tail;

        dma_sync_single_for_device(tup->uport.dev, tx_phys_addr,
                                   tup->tx_bytes, DMA_TO_DEVICE);

        tup->tx_dma_desc = dmaengine_prep_slave_single(tup->tx_dma_chan,
                                tx_phys_addr, tup->tx_bytes, DMA_MEM_TO_DEV,
                                DMA_PREP_INTERRUPT);
        if (!tup->tx_dma_desc) {
                dev_err(tup->uport.dev, "Not able to get desc for Tx\n");
                return -EIO;
        }

        tup->tx_dma_desc->callback = tegra_uart_tx_dma_complete;
        tup->tx_dma_desc->callback_param = tup;
        tup->tx_in_progress = TEGRA_UART_TX_DMA;
        tup->tx_bytes_requested = tup->tx_bytes;
        tup->tx_cookie = dmaengine_submit(tup->tx_dma_desc);
        dma_async_issue_pending(tup->tx_dma_chan);
        return 0;
}

static void tegra_uart_start_next_tx(struct tegra_uart_port *tup)
{
        struct tty_port *tport = &tup->uport.state->port;
        unsigned char *tail_ptr;
        unsigned long tail;
        unsigned int count;

        if (!tup->current_baud)
                return;

        count = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail_ptr,
                        UART_XMIT_SIZE);
        if (!count)
                return;

        tail = (unsigned long)tail_ptr;

        if (tup->use_tx_pio || count < TEGRA_UART_MIN_DMA)
                tegra_uart_start_pio_tx(tup, count);
        else if (BYTES_TO_ALIGN(tail) > 0)
                tegra_uart_start_pio_tx(tup, BYTES_TO_ALIGN(tail));
        else
                tegra_uart_start_tx_dma(tup, count);
}

/* Called by serial core driver with u->lock taken. */
static void tegra_uart_start_tx(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        struct tty_port *tport = &u->state->port;

        if (!kfifo_is_empty(&tport->xmit_fifo) && !tup->tx_in_progress)
                tegra_uart_start_next_tx(tup);
}

static unsigned int tegra_uart_tx_empty(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        unsigned int ret = 0;
        unsigned long flags;

        uart_port_lock_irqsave(u, &flags);
        if (!tup->tx_in_progress) {
                unsigned long lsr = tegra_uart_read(tup, UART_LSR);
                if ((lsr & TX_EMPTY_STATUS) == TX_EMPTY_STATUS)
                        ret = TIOCSER_TEMT;
        }
        uart_port_unlock_irqrestore(u, flags);
        return ret;
}

static void tegra_uart_stop_tx(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        struct dma_tx_state state;
        unsigned int count;

        if (tup->tx_in_progress != TEGRA_UART_TX_DMA)
                return;

        dmaengine_pause(tup->tx_dma_chan);
        dmaengine_tx_status(tup->tx_dma_chan, tup->tx_cookie, &state);
        dmaengine_terminate_all(tup->tx_dma_chan);
        count = tup->tx_bytes_requested - state.residue;
        async_tx_ack(tup->tx_dma_desc);
        uart_xmit_advance(&tup->uport, count);
        tup->tx_in_progress = 0;
}

static void tegra_uart_handle_tx_pio(struct tegra_uart_port *tup)
{
        struct tty_port *tport = &tup->uport.state->port;

        tegra_uart_fill_tx_fifo(tup, tup->tx_bytes);
        tup->tx_in_progress = 0;
        if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
                uart_write_wakeup(&tup->uport);
        tegra_uart_start_next_tx(tup);
}

static void tegra_uart_handle_rx_pio(struct tegra_uart_port *tup,
                struct tty_port *port)
{
        do {
                unsigned long lsr = 0;
                u8 ch, flag = TTY_NORMAL;

                lsr = tegra_uart_read(tup, UART_LSR);
                if (!(lsr & UART_LSR_DR))
                        break;

                flag = tegra_uart_decode_rx_error(tup, lsr);
                if (flag != TTY_NORMAL)
                        continue;

                ch = (unsigned char) tegra_uart_read(tup, UART_RX);
                tup->uport.icount.rx++;

                if (uart_handle_sysrq_char(&tup->uport, ch))
                        continue;

                if (tup->uport.ignore_status_mask & UART_LSR_DR)
                        continue;

                tty_insert_flip_char(port, ch, flag);
        } while (1);
}

static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
                                      struct tty_port *port,
                                      unsigned int count)
{
        int copied;

        /* If count is zero, then there is no data to be copied */
        if (!count)
                return;

        tup->uport.icount.rx += count;

        if (tup->uport.ignore_status_mask & UART_LSR_DR)
                return;

        dma_sync_single_for_cpu(tup->uport.dev, tup->rx_dma_buf_phys,
                                count, DMA_FROM_DEVICE);
        copied = tty_insert_flip_string(port,
                        ((unsigned char *)(tup->rx_dma_buf_virt)), count);
        if (copied != count) {
                WARN_ON(1);
                dev_err(tup->uport.dev, "RxData copy to tty layer failed\n");
        }
        dma_sync_single_for_device(tup->uport.dev, tup->rx_dma_buf_phys,
                                   count, DMA_TO_DEVICE);
}

static void do_handle_rx_pio(struct tegra_uart_port *tup)
{
        struct tty_struct *tty = tty_port_tty_get(&tup->uport.state->port);
        struct tty_port *port = &tup->uport.state->port;

        tegra_uart_handle_rx_pio(tup, port);
        if (tty) {
                tty_flip_buffer_push(port);
                tty_kref_put(tty);
        }
}

static void tegra_uart_rx_buffer_push(struct tegra_uart_port *tup,
                                      unsigned int residue)
{
        struct tty_port *port = &tup->uport.state->port;
        unsigned int count;

        async_tx_ack(tup->rx_dma_desc);
        count = tup->rx_bytes_requested - residue;

        /* If we are here, DMA is stopped */
        tegra_uart_copy_rx_to_tty(tup, port, count);

        do_handle_rx_pio(tup);
}

static void tegra_uart_rx_dma_complete(void *args)
{
        struct tegra_uart_port *tup = args;
        struct uart_port *u = &tup->uport;
        unsigned long flags;
        struct dma_tx_state state;
        enum dma_status status;

        uart_port_lock_irqsave(u, &flags);

        status = dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);

        if (status == DMA_IN_PROGRESS) {
                dev_dbg(tup->uport.dev, "RX DMA is in progress\n");
                goto done;
        }

        /* Deactivate flow control to stop sender */
        if (tup->rts_active)
                set_rts(tup, false);

        tup->rx_dma_active = false;
        tegra_uart_rx_buffer_push(tup, 0);
        tegra_uart_start_rx_dma(tup);

        /* Activate flow control to start transfer */
        if (tup->rts_active)
                set_rts(tup, true);

done:
        uart_port_unlock_irqrestore(u, flags);
}

static void tegra_uart_terminate_rx_dma(struct tegra_uart_port *tup)
{
        struct dma_tx_state state;

        if (!tup->rx_dma_active) {
                do_handle_rx_pio(tup);
                return;
        }

        dmaengine_pause(tup->rx_dma_chan);
        dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
        dmaengine_terminate_all(tup->rx_dma_chan);

        tegra_uart_rx_buffer_push(tup, state.residue);
        tup->rx_dma_active = false;
}

static void tegra_uart_handle_rx_dma(struct tegra_uart_port *tup)
{
        /* Deactivate flow control to stop sender */
        if (tup->rts_active)
                set_rts(tup, false);

        tegra_uart_terminate_rx_dma(tup);

        if (tup->rts_active)
                set_rts(tup, true);
}

static int tegra_uart_start_rx_dma(struct tegra_uart_port *tup)
{
        unsigned int count = TEGRA_UART_RX_DMA_BUFFER_SIZE;

        if (tup->rx_dma_active)
                return 0;

        tup->rx_dma_desc = dmaengine_prep_slave_single(tup->rx_dma_chan,
                                tup->rx_dma_buf_phys, count, DMA_DEV_TO_MEM,
                                DMA_PREP_INTERRUPT);
        if (!tup->rx_dma_desc) {
                dev_err(tup->uport.dev, "Not able to get desc for Rx\n");
                return -EIO;
        }

        tup->rx_dma_active = true;
        tup->rx_dma_desc->callback = tegra_uart_rx_dma_complete;
        tup->rx_dma_desc->callback_param = tup;
        tup->rx_bytes_requested = count;
        tup->rx_cookie = dmaengine_submit(tup->rx_dma_desc);
        dma_async_issue_pending(tup->rx_dma_chan);
        return 0;
}

static void tegra_uart_handle_modem_signal_change(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        unsigned long msr;

        msr = tegra_uart_read(tup, UART_MSR);
        if (!(msr & UART_MSR_ANY_DELTA))
                return;

        if (msr & UART_MSR_TERI)
                tup->uport.icount.rng++;
        if (msr & UART_MSR_DDSR)
                tup->uport.icount.dsr++;
        /* We may only get DDCD when HW init and reset */
        if (msr & UART_MSR_DDCD)
                uart_handle_dcd_change(&tup->uport, msr & UART_MSR_DCD);
        /* Will start/stop_tx accordingly */
        if (msr & UART_MSR_DCTS)
                uart_handle_cts_change(&tup->uport, msr & UART_MSR_CTS);
}

static irqreturn_t tegra_uart_isr(int irq, void *data)
{
        struct tegra_uart_port *tup = data;
        struct uart_port *u = &tup->uport;
        unsigned long iir;
        unsigned long ier;
        bool is_rx_start = false;
        bool is_rx_int = false;
        unsigned long flags;

        uart_port_lock_irqsave(u, &flags);
        while (1) {
                iir = tegra_uart_read(tup, UART_IIR);
                if (iir & UART_IIR_NO_INT) {
                        if (!tup->use_rx_pio && is_rx_int) {
                                tegra_uart_handle_rx_dma(tup);
                                if (tup->rx_in_progress) {
                                        ier = tup->ier_shadow;
                                        ier |= (UART_IER_RLSI | UART_IER_RTOIE |
                                                TEGRA_UART_IER_EORD | UART_IER_RDI);
                                        tup->ier_shadow = ier;
                                        tegra_uart_write(tup, ier, UART_IER);
                                }
                        } else if (is_rx_start) {
                                tegra_uart_start_rx_dma(tup);
                        }
                        uart_port_unlock_irqrestore(u, flags);
                        return IRQ_HANDLED;
                }

                switch ((iir >> 1) & 0x7) {
                case 0: /* Modem signal change interrupt */
                        tegra_uart_handle_modem_signal_change(u);
                        break;

                case 1: /* Transmit interrupt only triggered when using PIO */
                        tup->ier_shadow &= ~UART_IER_THRI;
                        tegra_uart_write(tup, tup->ier_shadow, UART_IER);
                        tegra_uart_handle_tx_pio(tup);
                        break;

                case 4: /* End of data */
                case 6: /* Rx timeout */
                        if (!tup->use_rx_pio) {
                                is_rx_int = tup->rx_in_progress;
                                /* Disable Rx interrupts */
                                ier = tup->ier_shadow;
                                ier &= ~(UART_IER_RDI | UART_IER_RLSI |
                                        UART_IER_RTOIE | TEGRA_UART_IER_EORD);
                                tup->ier_shadow = ier;
                                tegra_uart_write(tup, ier, UART_IER);
                                break;
                        }
                        fallthrough;
                case 2: /* Receive */
                        if (!tup->use_rx_pio) {
                                is_rx_start = tup->rx_in_progress;
                                tup->ier_shadow  &= ~UART_IER_RDI;
                                tegra_uart_write(tup, tup->ier_shadow,
                                                 UART_IER);
                        } else {
                                do_handle_rx_pio(tup);
                        }
                        break;

                case 3: /* Receive error */
                        tegra_uart_decode_rx_error(tup,
                                        tegra_uart_read(tup, UART_LSR));
                        break;

                case 5: /* break nothing to handle */
                case 7: /* break nothing to handle */
                        break;
                }
        }
}

static void tegra_uart_stop_rx(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        struct tty_port *port = &tup->uport.state->port;
        unsigned long ier;

        if (tup->rts_active)
                set_rts(tup, false);

        if (!tup->rx_in_progress)
                return;

        tegra_uart_wait_sym_time(tup, 1); /* wait one character interval */

        ier = tup->ier_shadow;
        ier &= ~(UART_IER_RDI | UART_IER_RLSI | UART_IER_RTOIE |
                                        TEGRA_UART_IER_EORD);
        tup->ier_shadow = ier;
        tegra_uart_write(tup, ier, UART_IER);
        tup->rx_in_progress = 0;

        if (!tup->use_rx_pio)
                tegra_uart_terminate_rx_dma(tup);
        else
                tegra_uart_handle_rx_pio(tup, port);
}

static void tegra_uart_hw_deinit(struct tegra_uart_port *tup)
{
        unsigned long flags;
        unsigned long char_time = DIV_ROUND_UP(10000000, tup->current_baud);
        unsigned long fifo_empty_time = tup->uport.fifosize * char_time;
        unsigned long wait_time;
        unsigned long lsr;
        unsigned long msr;
        unsigned long mcr;

        /* Disable interrupts */
        tegra_uart_write(tup, 0, UART_IER);

        lsr = tegra_uart_read(tup, UART_LSR);
        if ((lsr & UART_LSR_TEMT) != UART_LSR_TEMT) {
                msr = tegra_uart_read(tup, UART_MSR);
                mcr = tegra_uart_read(tup, UART_MCR);
                if ((mcr & TEGRA_UART_MCR_CTS_EN) && (msr & UART_MSR_CTS))
                        dev_err(tup->uport.dev,
                                "Tx Fifo not empty, CTS disabled, waiting\n");

                /* Wait for Tx fifo to be empty */
                while ((lsr & UART_LSR_TEMT) != UART_LSR_TEMT) {
                        wait_time = min(fifo_empty_time, 100lu);
                        udelay(wait_time);
                        fifo_empty_time -= wait_time;
                        if (!fifo_empty_time) {
                                msr = tegra_uart_read(tup, UART_MSR);
                                mcr = tegra_uart_read(tup, UART_MCR);
                                if ((mcr & TEGRA_UART_MCR_CTS_EN) &&
                                        (msr & UART_MSR_CTS))
                                        dev_err(tup->uport.dev,
                                                "Slave not ready\n");
                                break;
                        }
                        lsr = tegra_uart_read(tup, UART_LSR);
                }
        }

        uart_port_lock_irqsave(&tup->uport, &flags);
        /* Reset the Rx and Tx FIFOs */
        tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR);
        tup->current_baud = 0;
        uart_port_unlock_irqrestore(&tup->uport, flags);

        tup->rx_in_progress = 0;
        tup->tx_in_progress = 0;

        if (!tup->use_rx_pio)
                tegra_uart_dma_channel_free(tup, true);
        if (!tup->use_tx_pio)
                tegra_uart_dma_channel_free(tup, false);

        clk_disable_unprepare(tup->uart_clk);
}

static int tegra_uart_hw_init(struct tegra_uart_port *tup)
{
        int ret;

        tup->fcr_shadow = 0;
        tup->mcr_shadow = 0;
        tup->lcr_shadow = 0;
        tup->ier_shadow = 0;
        tup->current_baud = 0;

        ret = clk_prepare_enable(tup->uart_clk);
        if (ret) {
                dev_err(tup->uport.dev, "could not enable clk\n");
                return ret;
        }

        /* Reset the UART controller to clear all previous status.*/
        reset_control_assert(tup->rst);
        udelay(10);
        reset_control_deassert(tup->rst);

        tup->rx_in_progress = 0;
        tup->tx_in_progress = 0;

        /*
         * Set the trigger level
         *
         * For PIO mode:
         *
         * For receive, this will interrupt the CPU after that many number of
         * bytes are received, for the remaining bytes the receive timeout
         * interrupt is received. Rx high watermark is set to 4.
         *
         * For transmit, if the trasnmit interrupt is enabled, this will
         * interrupt the CPU when the number of entries in the FIFO reaches the
         * low watermark. Tx low watermark is set to 16 bytes.
         *
         * For DMA mode:
         *
         * Set the Tx trigger to 16. This should match the DMA burst size that
         * programmed in the DMA registers.
         */
        tup->fcr_shadow = UART_FCR_ENABLE_FIFO;

        if (tup->use_rx_pio) {
                tup->fcr_shadow |= UART_FCR_R_TRIG_11;
        } else {
                if (tup->cdata->max_dma_burst_bytes == 8)
                        tup->fcr_shadow |= UART_FCR_R_TRIG_10;
                else
                        tup->fcr_shadow |= UART_FCR_R_TRIG_01;
        }

        tup->fcr_shadow |= TEGRA_UART_TX_TRIG_16B;
        tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);

        /* Dummy read to ensure the write is posted */
        tegra_uart_read(tup, UART_SCR);

        if (tup->cdata->fifo_mode_enable_status) {
                ret = tegra_uart_wait_fifo_mode_enabled(tup);
                if (ret < 0) {
                        clk_disable_unprepare(tup->uart_clk);
                        dev_err(tup->uport.dev,
                                "Failed to enable FIFO mode: %d\n", ret);
                        return ret;
                }
        } else {
                /*
                 * For all tegra devices (up to t210), there is a hardware
                 * issue that requires software to wait for 3 UART clock
                 * periods after enabling the TX fifo, otherwise data could
                 * be lost.
                 */
                tegra_uart_wait_cycle_time(tup, 3);
        }

        /*
         * Initialize the UART with default configuration
         * (115200, N, 8, 1) so that the receive DMA buffer may be
         * enqueued
         */
        ret = tegra_set_baudrate(tup, TEGRA_UART_DEFAULT_BAUD);
        if (ret < 0) {
                clk_disable_unprepare(tup->uart_clk);
                dev_err(tup->uport.dev, "Failed to set baud rate\n");
                return ret;
        }
        if (!tup->use_rx_pio) {
                tup->lcr_shadow = TEGRA_UART_DEFAULT_LSR;
                tup->fcr_shadow |= UART_FCR_DMA_SELECT;
                tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
        } else {
                tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
        }
        tup->rx_in_progress = 1;

        /*
         * Enable IE_RXS for the receive status interrupts like line errors.
         * Enable IE_RX_TIMEOUT to get the bytes which cannot be DMA'd.
         *
         * EORD is different interrupt than RX_TIMEOUT - RX_TIMEOUT occurs when
         * the DATA is sitting in the FIFO and couldn't be transferred to the
         * DMA as the DMA size alignment (4 bytes) is not met. EORD will be
         * triggered when there is a pause of the incomming data stream for 4
         * characters long.
         *
         * For pauses in the data which is not aligned to 4 bytes, we get
         * both the EORD as well as RX_TIMEOUT - SW sees RX_TIMEOUT first
         * then the EORD.
         */
        tup->ier_shadow = UART_IER_RLSI | UART_IER_RTOIE | UART_IER_RDI;

        /*
         * If using DMA mode, enable EORD interrupt to notify about RX
         * completion.
         */
        if (!tup->use_rx_pio)
                tup->ier_shadow |= TEGRA_UART_IER_EORD;

        tegra_uart_write(tup, tup->ier_shadow, UART_IER);
        return 0;
}

static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,
                bool dma_to_memory)
{
        if (dma_to_memory) {
                dmaengine_terminate_all(tup->rx_dma_chan);
                dma_release_channel(tup->rx_dma_chan);
                dma_free_coherent(tup->uport.dev, TEGRA_UART_RX_DMA_BUFFER_SIZE,
                                tup->rx_dma_buf_virt, tup->rx_dma_buf_phys);
                tup->rx_dma_chan = NULL;
                tup->rx_dma_buf_phys = 0;
                tup->rx_dma_buf_virt = NULL;
        } else {
                dmaengine_terminate_all(tup->tx_dma_chan);
                dma_release_channel(tup->tx_dma_chan);
                dma_unmap_single(tup->uport.dev, tup->tx_dma_buf_phys,
                        UART_XMIT_SIZE, DMA_TO_DEVICE);
                tup->tx_dma_chan = NULL;
                tup->tx_dma_buf_phys = 0;
                tup->tx_dma_buf_virt = NULL;
        }
}

static int tegra_uart_dma_channel_allocate(struct tegra_uart_port *tup,
                        bool dma_to_memory)
{
        struct dma_chan *dma_chan;
        unsigned char *dma_buf;
        dma_addr_t dma_phys;
        int ret;
        struct dma_slave_config dma_sconfig;

        dma_chan = dma_request_chan(tup->uport.dev, dma_to_memory ? "rx" : "tx");
        if (IS_ERR(dma_chan)) {
                ret = PTR_ERR(dma_chan);
                dev_err(tup->uport.dev,
                        "DMA channel alloc failed: %d\n", ret);
                return ret;
        }

        if (dma_to_memory) {
                dma_buf = dma_alloc_coherent(tup->uport.dev,
                                TEGRA_UART_RX_DMA_BUFFER_SIZE,
                                 &dma_phys, GFP_KERNEL);
                if (!dma_buf) {
                        dev_err(tup->uport.dev,
                                "Not able to allocate the dma buffer\n");
                        dma_release_channel(dma_chan);
                        return -ENOMEM;
                }
                dma_sync_single_for_device(tup->uport.dev, dma_phys,
                                           TEGRA_UART_RX_DMA_BUFFER_SIZE,
                                           DMA_TO_DEVICE);
                dma_sconfig.src_addr = tup->uport.mapbase;
                dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
                dma_sconfig.src_maxburst = tup->cdata->max_dma_burst_bytes;
                tup->rx_dma_chan = dma_chan;
                tup->rx_dma_buf_virt = dma_buf;
                tup->rx_dma_buf_phys = dma_phys;
        } else {
                dma_buf = tup->uport.state->port.xmit_buf;
                dma_phys = dma_map_single(tup->uport.dev,
                        dma_buf, UART_XMIT_SIZE, DMA_TO_DEVICE);
                if (dma_mapping_error(tup->uport.dev, dma_phys)) {
                        dev_err(tup->uport.dev, "dma_map_single tx failed\n");
                        dma_release_channel(dma_chan);
                        return -ENOMEM;
                }
                dma_sconfig.dst_addr = tup->uport.mapbase;
                dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
                dma_sconfig.dst_maxburst = 16;
                tup->tx_dma_chan = dma_chan;
                tup->tx_dma_buf_virt = dma_buf;
                tup->tx_dma_buf_phys = dma_phys;
        }

        ret = dmaengine_slave_config(dma_chan, &dma_sconfig);
        if (ret < 0) {
                dev_err(tup->uport.dev,
                        "Dma slave config failed, err = %d\n", ret);
                tegra_uart_dma_channel_free(tup, dma_to_memory);
                return ret;
        }

        return 0;
}

static int tegra_uart_startup(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        int ret;

        if (!tup->use_tx_pio) {
                ret = tegra_uart_dma_channel_allocate(tup, false);
                if (ret < 0) {
                        dev_err(u->dev, "Tx Dma allocation failed, err = %d\n",
                                ret);
                        return ret;
                }
        }

        if (!tup->use_rx_pio) {
                ret = tegra_uart_dma_channel_allocate(tup, true);
                if (ret < 0) {
                        dev_err(u->dev, "Rx Dma allocation failed, err = %d\n",
                                ret);
                        goto fail_rx_dma;
                }
        }

        ret = tegra_uart_hw_init(tup);
        if (ret < 0) {
                dev_err(u->dev, "Uart HW init failed, err = %d\n", ret);
                goto fail_hw_init;
        }

        ret = request_irq(u->irq, tegra_uart_isr, 0,
                                dev_name(u->dev), tup);
        if (ret < 0) {
                dev_err(u->dev, "Failed to register ISR for IRQ %d\n", u->irq);
                goto fail_request_irq;
        }
        return 0;

fail_request_irq:
        /* tup->uart_clk is already enabled in tegra_uart_hw_init */
        clk_disable_unprepare(tup->uart_clk);
fail_hw_init:
        if (!tup->use_rx_pio)
                tegra_uart_dma_channel_free(tup, true);
fail_rx_dma:
        if (!tup->use_tx_pio)
                tegra_uart_dma_channel_free(tup, false);
        return ret;
}

/*
 * Flush any TX data submitted for DMA and PIO. Called when the
 * TX circular buffer is reset.
 */
static void tegra_uart_flush_buffer(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);

        tup->tx_bytes = 0;
        if (tup->tx_dma_chan)
                dmaengine_terminate_all(tup->tx_dma_chan);
}

static void tegra_uart_shutdown(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);

        tegra_uart_hw_deinit(tup);
        free_irq(u->irq, tup);
}

static void tegra_uart_enable_ms(struct uart_port *u)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);

        if (tup->enable_modem_interrupt) {
                tup->ier_shadow |= UART_IER_MSI;
                tegra_uart_write(tup, tup->ier_shadow, UART_IER);
        }
}

static void tegra_uart_set_termios(struct uart_port *u,
                                   struct ktermios *termios,
                                   const struct ktermios *oldtermios)
{
        struct tegra_uart_port *tup = to_tegra_uport(u);
        unsigned int baud;
        unsigned long flags;
        unsigned int lcr;
        unsigned char char_bits;
        struct clk *parent_clk = clk_get_parent(tup->uart_clk);
        unsigned long parent_clk_rate = clk_get_rate(parent_clk);
        int max_divider = (tup->cdata->support_clk_src_div) ? 0x7FFF : 0xFFFF;
        int ret;

        max_divider *= 16;
        uart_port_lock_irqsave(u, &flags);

        /* Changing configuration, it is safe to stop any rx now */
        if (tup->rts_active)
                set_rts(tup, false);

        /* Clear all interrupts as configuration is going to be changed */
        tegra_uart_write(tup, tup->ier_shadow | UART_IER_RDI, UART_IER);
        tegra_uart_read(tup, UART_IER);
        tegra_uart_write(tup, 0, UART_IER);
        tegra_uart_read(tup, UART_IER);

        /* Parity */
        lcr = tup->lcr_shadow;
        lcr &= ~UART_LCR_PARITY;

        /* CMSPAR isn't supported by this driver */
        termios->c_cflag &= ~CMSPAR;

        if ((termios->c_cflag & PARENB) == PARENB) {
                if (termios->c_cflag & PARODD) {
                        lcr |= UART_LCR_PARITY;
                        lcr &= ~UART_LCR_EPAR;
                        lcr &= ~UART_LCR_SPAR;
                } else {
                        lcr |= UART_LCR_PARITY;
                        lcr |= UART_LCR_EPAR;
                        lcr &= ~UART_LCR_SPAR;
                }
        }

        char_bits = tty_get_char_size(termios->c_cflag);
        lcr &= ~UART_LCR_WLEN8;
        lcr |= UART_LCR_WLEN(char_bits);

        /* Stop bits */
        if (termios->c_cflag & CSTOPB)
                lcr |= UART_LCR_STOP;
        else
                lcr &= ~UART_LCR_STOP;

        tegra_uart_write(tup, lcr, UART_LCR);
        tup->lcr_shadow = lcr;
        tup->symb_bit = tty_get_frame_size(termios->c_cflag);

        /* Baud rate. */
        baud = uart_get_baud_rate(u, termios, oldtermios,
                        parent_clk_rate/max_divider,
                        parent_clk_rate/16);
        uart_port_unlock_irqrestore(u, flags);
        ret = tegra_set_baudrate(tup, baud);
        if (ret < 0) {
                dev_err(tup->uport.dev, "Failed to set baud rate\n");
                return;
        }
        if (tty_termios_baud_rate(termios))
                tty_termios_encode_baud_rate(termios, baud, baud);
        uart_port_lock_irqsave(u, &flags);

        /* Flow control */
        if (termios->c_cflag & CRTSCTS) {
                tup->mcr_shadow |= TEGRA_UART_MCR_CTS_EN;
                tup->mcr_shadow &= ~TEGRA_UART_MCR_RTS_EN;
                tegra_uart_write(tup, tup->mcr_shadow, UART_MCR);
                /* if top layer has asked to set rts active then do so here */
                if (tup->rts_active)
                        set_rts(tup, true);
        } else {
                tup->mcr_shadow &= ~TEGRA_UART_MCR_CTS_EN;
                tup->mcr_shadow &= ~TEGRA_UART_MCR_RTS_EN;
                tegra_uart_write(tup, tup->mcr_shadow, UART_MCR);
        }

        /* update the port timeout based on new settings */
        uart_update_timeout(u, termios->c_cflag, baud);

        /* Make sure all writes have completed */
        tegra_uart_read(tup, UART_IER);

        /* Re-enable interrupt */
        tegra_uart_write(tup, tup->ier_shadow, UART_IER);
        tegra_uart_read(tup, UART_IER);

        tup->uport.ignore_status_mask = 0;
        /* Ignore all characters if CREAD is not set */
        if ((termios->c_cflag & CREAD) == 0)
                tup->uport.ignore_status_mask |= UART_LSR_DR;
        if (termios->c_iflag & IGNBRK)
                tup->uport.ignore_status_mask |= UART_LSR_BI;

        uart_port_unlock_irqrestore(u, flags);
}

static const char *tegra_uart_type(struct uart_port *u)
{
        return TEGRA_UART_TYPE;
}

static const struct uart_ops tegra_uart_ops = {
        .tx_empty       = tegra_uart_tx_empty,
        .set_mctrl      = tegra_uart_set_mctrl,
        .get_mctrl      = tegra_uart_get_mctrl,
        .stop_tx        = tegra_uart_stop_tx,
        .start_tx       = tegra_uart_start_tx,
        .stop_rx        = tegra_uart_stop_rx,
        .flush_buffer   = tegra_uart_flush_buffer,
        .enable_ms      = tegra_uart_enable_ms,
        .break_ctl      = tegra_uart_break_ctl,
        .startup        = tegra_uart_startup,
        .shutdown       = tegra_uart_shutdown,
        .set_termios    = tegra_uart_set_termios,
        .type           = tegra_uart_type,
        .request_port   = tegra_uart_request_port,
        .release_port   = tegra_uart_release_port,
};

static struct uart_driver tegra_uart_driver = {
        .owner          = THIS_MODULE,
        .driver_name    = "tegra_hsuart",
        .dev_name       = "ttyTHS",
        .cons           = NULL,
        .nr             = TEGRA_UART_MAXIMUM,
};

static int tegra_uart_parse_dt(struct platform_device *pdev,
        struct tegra_uart_port *tup)
{
        struct device_node *np = pdev->dev.of_node;
        int port;
        int ret;
        int index;
        u32 pval;
        int count;
        int n_entries;

        port = of_alias_get_id(np, "serial");
        if (port < 0) {
                dev_err(&pdev->dev, "failed to get alias id, errno %d\n", port);
                return port;
        }
        tup->uport.line = port;

        tup->enable_modem_interrupt = of_property_read_bool(np,
                                        "nvidia,enable-modem-interrupt");

        index = of_property_match_string(np, "dma-names", "rx");
        if (index < 0) {
                tup->use_rx_pio = true;
                dev_info(&pdev->dev, "RX in PIO mode\n");
        }
        index = of_property_match_string(np, "dma-names", "tx");
        if (index < 0) {
                tup->use_tx_pio = true;
                dev_info(&pdev->dev, "TX in PIO mode\n");
        }

        n_entries = of_property_count_u32_elems(np, "nvidia,adjust-baud-rates");
        if (n_entries > 0) {
                tup->n_adjustable_baud_rates = n_entries / 3;
                tup->baud_tolerance =
                devm_kzalloc(&pdev->dev, (tup->n_adjustable_baud_rates) *
                             sizeof(*tup->baud_tolerance), GFP_KERNEL);
                if (!tup->baud_tolerance)
                        return -ENOMEM;
                for (count = 0, index = 0; count < n_entries; count += 3,
                     index++) {
                        ret =
                        of_property_read_u32_index(np,
                                                   "nvidia,adjust-baud-rates",
                                                   count, &pval);
                        if (!ret)
                                tup->baud_tolerance[index].lower_range_baud =
                                pval;
                        ret =
                        of_property_read_u32_index(np,
                                                   "nvidia,adjust-baud-rates",
                                                   count + 1, &pval);
                        if (!ret)
                                tup->baud_tolerance[index].upper_range_baud =
                                pval;
                        ret =
                        of_property_read_u32_index(np,
                                                   "nvidia,adjust-baud-rates",
                                                   count + 2, &pval);
                        if (!ret)
                                tup->baud_tolerance[index].tolerance =
                                (s32)pval;
                }
        } else {
                tup->n_adjustable_baud_rates = 0;
        }

        return 0;
}

static struct tegra_uart_chip_data tegra20_uart_chip_data = {
        .tx_fifo_full_status            = false,
        .allow_txfifo_reset_fifo_mode   = true,
        .support_clk_src_div            = false,
        .fifo_mode_enable_status        = false,
        .uart_max_port                  = 5,
        .max_dma_burst_bytes            = 4,
        .error_tolerance_low_range      = -4,
        .error_tolerance_high_range     = 4,
};

static struct tegra_uart_chip_data tegra30_uart_chip_data = {
        .tx_fifo_full_status            = true,
        .allow_txfifo_reset_fifo_mode   = false,
        .support_clk_src_div            = true,
        .fifo_mode_enable_status        = false,
        .uart_max_port                  = 5,
        .max_dma_burst_bytes            = 4,
        .error_tolerance_low_range      = -4,
        .error_tolerance_high_range     = 4,
};

static struct tegra_uart_chip_data tegra186_uart_chip_data = {
        .tx_fifo_full_status            = true,
        .allow_txfifo_reset_fifo_mode   = false,
        .support_clk_src_div            = true,
        .fifo_mode_enable_status        = true,
        .uart_max_port                  = 8,
        .max_dma_burst_bytes            = 8,
        .error_tolerance_low_range      = 0,
        .error_tolerance_high_range     = 4,
};

static struct tegra_uart_chip_data tegra194_uart_chip_data = {
        .tx_fifo_full_status            = true,
        .allow_txfifo_reset_fifo_mode   = false,
        .support_clk_src_div            = true,
        .fifo_mode_enable_status        = true,
        .uart_max_port                  = 8,
        .max_dma_burst_bytes            = 8,
        .error_tolerance_low_range      = -2,
        .error_tolerance_high_range     = 2,
};

static const struct of_device_id tegra_uart_of_match[] = {
        {
                .compatible     = "nvidia,tegra30-hsuart",
                .data           = &tegra30_uart_chip_data,
        }, {
                .compatible     = "nvidia,tegra20-hsuart",
                .data           = &tegra20_uart_chip_data,
        }, {
                .compatible     = "nvidia,tegra186-hsuart",
                .data           = &tegra186_uart_chip_data,
        }, {
                .compatible     = "nvidia,tegra194-hsuart",
                .data           = &tegra194_uart_chip_data,
        }, {
        },
};
MODULE_DEVICE_TABLE(of, tegra_uart_of_match);

static int tegra_uart_probe(struct platform_device *pdev)
{
        struct tegra_uart_port *tup;
        struct uart_port *u;
        struct resource *resource;
        int ret;
        const struct tegra_uart_chip_data *cdata;

        cdata = of_device_get_match_data(&pdev->dev);
        if (!cdata) {
                dev_err(&pdev->dev, "Error: No device match found\n");
                return -ENODEV;
        }

        tup = devm_kzalloc(&pdev->dev, sizeof(*tup), GFP_KERNEL);
        if (!tup) {
                dev_err(&pdev->dev, "Failed to allocate memory for tup\n");
                return -ENOMEM;
        }

        ret = tegra_uart_parse_dt(pdev, tup);
        if (ret < 0)
                return ret;

        u = &tup->uport;
        u->dev = &pdev->dev;
        u->ops = &tegra_uart_ops;
        u->type = PORT_TEGRA;
        u->fifosize = 32;
        tup->cdata = cdata;

        platform_set_drvdata(pdev, tup);

        u->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &resource);
        if (IS_ERR(u->membase))
                return PTR_ERR(u->membase);
        u->mapbase = resource->start;

        tup->uart_clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(tup->uart_clk))
                return dev_err_probe(&pdev->dev, PTR_ERR(tup->uart_clk), "Couldn't get the clock");

        tup->rst = devm_reset_control_get_exclusive(&pdev->dev, "serial");
        if (IS_ERR(tup->rst)) {
                dev_err(&pdev->dev, "Couldn't get the reset\n");
                return PTR_ERR(tup->rst);
        }

        u->iotype = UPIO_MEM32;
        ret = platform_get_irq(pdev, 0);
        if (ret < 0)
                return ret;
        u->irq = ret;
        u->regshift = 2;
        ret = uart_add_one_port(&tegra_uart_driver, u);
        if (ret < 0) {
                dev_err(&pdev->dev, "Failed to add uart port, err %d\n", ret);
                return ret;
        }
        return ret;
}

static void tegra_uart_remove(struct platform_device *pdev)
{
        struct tegra_uart_port *tup = platform_get_drvdata(pdev);
        struct uart_port *u = &tup->uport;

        uart_remove_one_port(&tegra_uart_driver, u);
}

#ifdef CONFIG_PM_SLEEP
static int tegra_uart_suspend(struct device *dev)
{
        struct tegra_uart_port *tup = dev_get_drvdata(dev);
        struct uart_port *u = &tup->uport;

        return uart_suspend_port(&tegra_uart_driver, u);
}

static int tegra_uart_resume(struct device *dev)
{
        struct tegra_uart_port *tup = dev_get_drvdata(dev);
        struct uart_port *u = &tup->uport;

        return uart_resume_port(&tegra_uart_driver, u);
}
#endif

static const struct dev_pm_ops tegra_uart_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(tegra_uart_suspend, tegra_uart_resume)
};

static struct platform_driver tegra_uart_platform_driver = {
        .probe          = tegra_uart_probe,
        .remove         = tegra_uart_remove,
        .driver         = {
                .name   = "serial-tegra",
                .of_match_table = tegra_uart_of_match,
                .pm     = &tegra_uart_pm_ops,
        },
};

static int __init tegra_uart_init(void)
{
        int ret;
        struct device_node *node;
        const struct of_device_id *match = NULL;
        const struct tegra_uart_chip_data *cdata = NULL;

        node = of_find_matching_node(NULL, tegra_uart_of_match);
        if (node)
                match = of_match_node(tegra_uart_of_match, node);
        of_node_put(node);
        if (match)
                cdata = match->data;
        if (cdata)
                tegra_uart_driver.nr = cdata->uart_max_port;

        ret = uart_register_driver(&tegra_uart_driver);
        if (ret < 0) {
                pr_err("Could not register %s driver\n",
                       tegra_uart_driver.driver_name);
                return ret;
        }

        ret = platform_driver_register(&tegra_uart_platform_driver);
        if (ret < 0) {
                pr_err("Uart platform driver register failed, e = %d\n", ret);
                uart_unregister_driver(&tegra_uart_driver);
                return ret;
        }
        return 0;
}

static void __exit tegra_uart_exit(void)
{
        pr_info("Unloading tegra uart driver\n");
        platform_driver_unregister(&tegra_uart_platform_driver);
        uart_unregister_driver(&tegra_uart_driver);
}

module_init(tegra_uart_init);
module_exit(tegra_uart_exit);

MODULE_ALIAS("platform:serial-tegra");
MODULE_DESCRIPTION("High speed UART driver for tegra chipset");
MODULE_AUTHOR("Laxman Dewangan <ldewangan@nvidia.com>");
MODULE_LICENSE("GPL v2");