root/drivers/tty/serial/sprd_serial.c
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2012-2015 Spreadtrum Communications Inc.
 */

#include <linux/clk.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dma/sprd-dma.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>

/* device name */
#define UART_NR_MAX             8
#define SPRD_TTY_NAME           "ttyS"
#define SPRD_FIFO_SIZE          128
#define SPRD_DEF_RATE           26000000
#define SPRD_BAUD_IO_LIMIT      3000000
#define SPRD_TIMEOUT            256000

/* the offset of serial registers and BITs for them */
/* data registers */
#define SPRD_TXD                0x0000
#define SPRD_RXD                0x0004

/* line status register and its BITs  */
#define SPRD_LSR                0x0008
#define SPRD_LSR_OE             BIT(4)
#define SPRD_LSR_FE             BIT(3)
#define SPRD_LSR_PE             BIT(2)
#define SPRD_LSR_BI             BIT(7)
#define SPRD_LSR_TX_OVER        BIT(15)

/* data number in TX and RX fifo */
#define SPRD_STS1               0x000C
#define SPRD_RX_FIFO_CNT_MASK   GENMASK(7, 0)
#define SPRD_TX_FIFO_CNT_MASK   GENMASK(15, 8)

/* interrupt enable register and its BITs */
#define SPRD_IEN                0x0010
#define SPRD_IEN_RX_FULL        BIT(0)
#define SPRD_IEN_TX_EMPTY       BIT(1)
#define SPRD_IEN_BREAK_DETECT   BIT(7)
#define SPRD_IEN_TIMEOUT        BIT(13)
#define SPRD_IEN_DATA_TIMEOUT   BIT(17)

/* interrupt clear register */
#define SPRD_ICLR               0x0014
#define SPRD_ICLR_TIMEOUT       BIT(13)
#define SPRD_ICLR_DATA_TIMEOUT  BIT(17)

/* line control register */
#define SPRD_LCR                0x0018
#define SPRD_LCR_STOP_1BIT      0x10
#define SPRD_LCR_STOP_2BIT      0x30
#define SPRD_LCR_DATA_LEN       (BIT(2) | BIT(3))
#define SPRD_LCR_DATA_LEN5      0x0
#define SPRD_LCR_DATA_LEN6      0x4
#define SPRD_LCR_DATA_LEN7      0x8
#define SPRD_LCR_DATA_LEN8      0xc
#define SPRD_LCR_PARITY         (BIT(0) | BIT(1))
#define SPRD_LCR_PARITY_EN      0x2
#define SPRD_LCR_EVEN_PAR       0x0
#define SPRD_LCR_ODD_PAR        0x1

/* control register 1 */
#define SPRD_CTL1               0x001C
#define SPRD_DMA_EN             BIT(15)
#define SPRD_LOOPBACK_EN        BIT(14)
#define RX_HW_FLOW_CTL_THLD     BIT(6)
#define RX_HW_FLOW_CTL_EN       BIT(7)
#define TX_HW_FLOW_CTL_EN       BIT(8)
#define RX_TOUT_THLD_DEF        0x3E00
#define RX_HFC_THLD_DEF         0x40

/* fifo threshold register */
#define SPRD_CTL2               0x0020
#define THLD_TX_EMPTY           0x40
#define THLD_TX_EMPTY_SHIFT     8
#define THLD_RX_FULL            0x40
#define THLD_RX_FULL_MASK       GENMASK(6, 0)

/* config baud rate register */
#define SPRD_CLKD0              0x0024
#define SPRD_CLKD0_MASK         GENMASK(15, 0)
#define SPRD_CLKD1              0x0028
#define SPRD_CLKD1_MASK         GENMASK(20, 16)
#define SPRD_CLKD1_SHIFT        16

/* interrupt mask status register */
#define SPRD_IMSR               0x002C
#define SPRD_IMSR_RX_FIFO_FULL  BIT(0)
#define SPRD_IMSR_TX_FIFO_EMPTY BIT(1)
#define SPRD_IMSR_BREAK_DETECT  BIT(7)
#define SPRD_IMSR_TIMEOUT       BIT(13)
#define SPRD_IMSR_DATA_TIMEOUT  BIT(17)
#define SPRD_DEFAULT_SOURCE_CLK 26000000

#define SPRD_RX_DMA_STEP        1
#define SPRD_RX_FIFO_FULL       1
#define SPRD_TX_FIFO_FULL       0x20
#define SPRD_UART_RX_SIZE       (UART_XMIT_SIZE / 4)

struct sprd_uart_dma {
        struct dma_chan *chn;
        unsigned char *virt;
        dma_addr_t phys_addr;
        dma_cookie_t cookie;
        u32 trans_len;
        bool enable;
};

struct sprd_uart_data {
        unsigned int timeout_ien;
        unsigned int timeout_iclr;
        unsigned int timeout_imsr;
};

struct sprd_uart_port {
        struct uart_port port;
        char name[16];
        struct clk *clk;
        struct sprd_uart_dma tx_dma;
        struct sprd_uart_dma rx_dma;
        dma_addr_t pos;
        unsigned char *rx_buf_tail;
        const struct sprd_uart_data *pdata;
};

static struct sprd_uart_port *sprd_port[UART_NR_MAX];
static int sprd_ports_num;

static int sprd_start_dma_rx(struct uart_port *port);
static int sprd_tx_dma_config(struct uart_port *port);

static const struct sprd_uart_data sc9836_data = {
        .timeout_ien = SPRD_IEN_TIMEOUT,
        .timeout_iclr = SPRD_ICLR_TIMEOUT,
        .timeout_imsr = SPRD_IMSR_TIMEOUT,
};

static const struct sprd_uart_data sc9632_data = {
        .timeout_ien = SPRD_IEN_DATA_TIMEOUT,
        .timeout_iclr = SPRD_ICLR_DATA_TIMEOUT,
        .timeout_imsr = SPRD_IMSR_DATA_TIMEOUT,
};

static inline unsigned int serial_in(struct uart_port *port,
                                     unsigned int offset)
{
        return readl_relaxed(port->membase + offset);
}

static inline void serial_out(struct uart_port *port, unsigned int offset,
                              int value)
{
        writel_relaxed(value, port->membase + offset);
}

static unsigned int sprd_tx_empty(struct uart_port *port)
{
        if (serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
                return 0;
        else
                return TIOCSER_TEMT;
}

static unsigned int sprd_get_mctrl(struct uart_port *port)
{
        return TIOCM_DSR | TIOCM_CTS;
}

static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
        u32 val = serial_in(port, SPRD_CTL1);

        if (mctrl & TIOCM_LOOP)
                val |= SPRD_LOOPBACK_EN;
        else
                val &= ~SPRD_LOOPBACK_EN;

        serial_out(port, SPRD_CTL1, val);
}

static void sprd_stop_rx(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        unsigned int ien, iclr;

        if (sp->rx_dma.enable)
                dmaengine_terminate_all(sp->rx_dma.chn);

        iclr = serial_in(port, SPRD_ICLR);
        ien = serial_in(port, SPRD_IEN);

        ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
        iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;

        serial_out(port, SPRD_IEN, ien);
        serial_out(port, SPRD_ICLR, iclr);
}

static void sprd_uart_dma_enable(struct uart_port *port, bool enable)
{
        u32 val = serial_in(port, SPRD_CTL1);

        if (enable)
                val |= SPRD_DMA_EN;
        else
                val &= ~SPRD_DMA_EN;

        serial_out(port, SPRD_CTL1, val);
}

static void sprd_stop_tx_dma(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        struct dma_tx_state state;
        u32 trans_len;

        dmaengine_pause(sp->tx_dma.chn);

        dmaengine_tx_status(sp->tx_dma.chn, sp->tx_dma.cookie, &state);
        if (state.residue) {
                trans_len = state.residue - sp->tx_dma.phys_addr;
                uart_xmit_advance(port, trans_len);
                dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
                                 sp->tx_dma.trans_len, DMA_TO_DEVICE);
        }

        dmaengine_terminate_all(sp->tx_dma.chn);
        sp->tx_dma.trans_len = 0;
}

static int sprd_tx_buf_remap(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        struct tty_port *tport = &port->state->port;
        unsigned char *tail;

        sp->tx_dma.trans_len = kfifo_out_linear_ptr(&tport->xmit_fifo, &tail,
                        UART_XMIT_SIZE);

        sp->tx_dma.phys_addr = dma_map_single(port->dev, tail,
                                              sp->tx_dma.trans_len,
                                              DMA_TO_DEVICE);
        return dma_mapping_error(port->dev, sp->tx_dma.phys_addr);
}

static void sprd_complete_tx_dma(void *data)
{
        struct uart_port *port = (struct uart_port *)data;
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        struct tty_port *tport = &port->state->port;
        unsigned long flags;

        uart_port_lock_irqsave(port, &flags);
        dma_unmap_single(port->dev, sp->tx_dma.phys_addr,
                         sp->tx_dma.trans_len, DMA_TO_DEVICE);

        uart_xmit_advance(port, sp->tx_dma.trans_len);

        if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)
                uart_write_wakeup(port);

        if (kfifo_is_empty(&tport->xmit_fifo) || sprd_tx_buf_remap(port) ||
            sprd_tx_dma_config(port))
                sp->tx_dma.trans_len = 0;

        uart_port_unlock_irqrestore(port, flags);
}

static int sprd_uart_dma_submit(struct uart_port *port,
                                struct sprd_uart_dma *ud, u32 trans_len,
                                enum dma_transfer_direction direction,
                                dma_async_tx_callback callback)
{
        struct dma_async_tx_descriptor *dma_des;
        unsigned long flags;

        flags = SPRD_DMA_FLAGS(SPRD_DMA_CHN_MODE_NONE,
                               SPRD_DMA_NO_TRG,
                               SPRD_DMA_FRAG_REQ,
                               SPRD_DMA_TRANS_INT);

        dma_des = dmaengine_prep_slave_single(ud->chn, ud->phys_addr, trans_len,
                                              direction, flags);
        if (!dma_des)
                return -ENODEV;

        dma_des->callback = callback;
        dma_des->callback_param = port;

        ud->cookie = dmaengine_submit(dma_des);
        if (dma_submit_error(ud->cookie))
                return dma_submit_error(ud->cookie);

        dma_async_issue_pending(ud->chn);

        return 0;
}

static int sprd_tx_dma_config(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        u32 burst = sp->tx_dma.trans_len > SPRD_TX_FIFO_FULL ?
                SPRD_TX_FIFO_FULL : sp->tx_dma.trans_len;
        int ret;
        struct dma_slave_config cfg = {
                .dst_addr = port->mapbase + SPRD_TXD,
                .src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
                .dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
                .src_maxburst = burst,
        };

        ret = dmaengine_slave_config(sp->tx_dma.chn, &cfg);
        if (ret < 0)
                return ret;

        return sprd_uart_dma_submit(port, &sp->tx_dma, sp->tx_dma.trans_len,
                                    DMA_MEM_TO_DEV, sprd_complete_tx_dma);
}

static void sprd_start_tx_dma(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        struct tty_port *tport = &port->state->port;

        if (port->x_char) {
                serial_out(port, SPRD_TXD, port->x_char);
                port->icount.tx++;
                port->x_char = 0;
                return;
        }

        if (kfifo_is_empty(&tport->xmit_fifo) || uart_tx_stopped(port)) {
                sprd_stop_tx_dma(port);
                return;
        }

        if (sp->tx_dma.trans_len)
                return;

        if (sprd_tx_buf_remap(port) || sprd_tx_dma_config(port))
                sp->tx_dma.trans_len = 0;
}

static void sprd_rx_full_thld(struct uart_port *port, u32 thld)
{
        u32 val = serial_in(port, SPRD_CTL2);

        val &= ~THLD_RX_FULL_MASK;
        val |= thld & THLD_RX_FULL_MASK;
        serial_out(port, SPRD_CTL2, val);
}

static int sprd_rx_alloc_buf(struct sprd_uart_port *sp)
{
        sp->rx_dma.virt = dma_alloc_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
                                             &sp->rx_dma.phys_addr, GFP_KERNEL);
        if (!sp->rx_dma.virt)
                return -ENOMEM;

        return 0;
}

static void sprd_rx_free_buf(struct sprd_uart_port *sp)
{
        if (sp->rx_dma.virt)
                dma_free_coherent(sp->port.dev, SPRD_UART_RX_SIZE,
                                  sp->rx_dma.virt, sp->rx_dma.phys_addr);
        sp->rx_dma.virt = NULL;
}

static int sprd_rx_dma_config(struct uart_port *port, u32 burst)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        struct dma_slave_config cfg = {
                .src_addr = port->mapbase + SPRD_RXD,
                .src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
                .dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE,
                .src_maxburst = burst,
        };

        return dmaengine_slave_config(sp->rx_dma.chn, &cfg);
}

static void sprd_uart_dma_rx(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        struct tty_port *tty = &port->state->port;

        port->icount.rx += sp->rx_dma.trans_len;
        tty_insert_flip_string(tty, sp->rx_buf_tail, sp->rx_dma.trans_len);
        tty_flip_buffer_push(tty);
}

static void sprd_uart_dma_irq(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        struct dma_tx_state state;
        enum dma_status status;

        status = dmaengine_tx_status(sp->rx_dma.chn,
                                     sp->rx_dma.cookie, &state);
        if (status == DMA_ERROR)
                sprd_stop_rx(port);

        if (!state.residue && sp->pos == sp->rx_dma.phys_addr)
                return;

        if (!state.residue) {
                sp->rx_dma.trans_len = SPRD_UART_RX_SIZE +
                        sp->rx_dma.phys_addr - sp->pos;
                sp->pos = sp->rx_dma.phys_addr;
        } else {
                sp->rx_dma.trans_len = state.residue - sp->pos;
                sp->pos = state.residue;
        }

        sprd_uart_dma_rx(port);
        sp->rx_buf_tail += sp->rx_dma.trans_len;
}

static void sprd_complete_rx_dma(void *data)
{
        struct uart_port *port = (struct uart_port *)data;
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        struct dma_tx_state state;
        enum dma_status status;
        unsigned long flags;

        uart_port_lock_irqsave(port, &flags);

        status = dmaengine_tx_status(sp->rx_dma.chn,
                                     sp->rx_dma.cookie, &state);
        if (status != DMA_COMPLETE) {
                sprd_stop_rx(port);
                uart_port_unlock_irqrestore(port, flags);
                return;
        }

        if (sp->pos != sp->rx_dma.phys_addr) {
                sp->rx_dma.trans_len =  SPRD_UART_RX_SIZE +
                        sp->rx_dma.phys_addr - sp->pos;
                sprd_uart_dma_rx(port);
                sp->rx_buf_tail += sp->rx_dma.trans_len;
        }

        if (sprd_start_dma_rx(port))
                sprd_stop_rx(port);

        uart_port_unlock_irqrestore(port, flags);
}

static int sprd_start_dma_rx(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);
        int ret;

        if (!sp->rx_dma.enable)
                return 0;

        sp->pos = sp->rx_dma.phys_addr;
        sp->rx_buf_tail = sp->rx_dma.virt;
        sprd_rx_full_thld(port, SPRD_RX_FIFO_FULL);
        ret = sprd_rx_dma_config(port, SPRD_RX_DMA_STEP);
        if (ret)
                return ret;

        return sprd_uart_dma_submit(port, &sp->rx_dma, SPRD_UART_RX_SIZE,
                                    DMA_DEV_TO_MEM, sprd_complete_rx_dma);
}

static void sprd_release_dma(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);

        sprd_uart_dma_enable(port, false);

        if (sp->rx_dma.enable)
                dma_release_channel(sp->rx_dma.chn);

        if (sp->tx_dma.enable)
                dma_release_channel(sp->tx_dma.chn);

        sp->tx_dma.enable = false;
        sp->rx_dma.enable = false;
}

static void sprd_request_dma(struct uart_port *port)
{
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);

        sp->tx_dma.enable = true;
        sp->rx_dma.enable = true;

        sp->tx_dma.chn = dma_request_chan(port->dev, "tx");
        if (IS_ERR(sp->tx_dma.chn)) {
                dev_err(port->dev, "request TX DMA channel failed, ret = %ld\n",
                        PTR_ERR(sp->tx_dma.chn));
                sp->tx_dma.enable = false;
        }

        sp->rx_dma.chn = dma_request_chan(port->dev, "rx");
        if (IS_ERR(sp->rx_dma.chn)) {
                dev_err(port->dev, "request RX DMA channel failed, ret = %ld\n",
                        PTR_ERR(sp->rx_dma.chn));
                sp->rx_dma.enable = false;
        }
}

static void sprd_stop_tx(struct uart_port *port)
{
        struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
                                                 port);
        unsigned int ien, iclr;

        if (sp->tx_dma.enable) {
                sprd_stop_tx_dma(port);
                return;
        }

        iclr = serial_in(port, SPRD_ICLR);
        ien = serial_in(port, SPRD_IEN);

        iclr |= SPRD_IEN_TX_EMPTY;
        ien &= ~SPRD_IEN_TX_EMPTY;

        serial_out(port, SPRD_IEN, ien);
        serial_out(port, SPRD_ICLR, iclr);
}

static void sprd_start_tx(struct uart_port *port)
{
        struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
                                                 port);
        unsigned int ien;

        if (sp->tx_dma.enable) {
                sprd_start_tx_dma(port);
                return;
        }

        ien = serial_in(port, SPRD_IEN);
        if (!(ien & SPRD_IEN_TX_EMPTY)) {
                ien |= SPRD_IEN_TX_EMPTY;
                serial_out(port, SPRD_IEN, ien);
        }
}

/* The Sprd serial does not support this function. */
static void sprd_break_ctl(struct uart_port *port, int break_state)
{
        /* nothing to do */
}

static int handle_lsr_errors(struct uart_port *port,
                             u8 *flag,
                             unsigned int *lsr)
{
        int ret = 0;

        /* statistics */
        if (*lsr & SPRD_LSR_BI) {
                *lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
                port->icount.brk++;
                ret = uart_handle_break(port);
                if (ret)
                        return ret;
        } else if (*lsr & SPRD_LSR_PE)
                port->icount.parity++;
        else if (*lsr & SPRD_LSR_FE)
                port->icount.frame++;
        if (*lsr & SPRD_LSR_OE)
                port->icount.overrun++;

        /* mask off conditions which should be ignored */
        *lsr &= port->read_status_mask;
        if (*lsr & SPRD_LSR_BI)
                *flag = TTY_BREAK;
        else if (*lsr & SPRD_LSR_PE)
                *flag = TTY_PARITY;
        else if (*lsr & SPRD_LSR_FE)
                *flag = TTY_FRAME;

        return ret;
}

static inline void sprd_rx(struct uart_port *port)
{
        struct sprd_uart_port *sp = container_of(port, struct sprd_uart_port,
                                                 port);
        struct tty_port *tty = &port->state->port;
        unsigned int lsr, max_count = SPRD_TIMEOUT;
        u8 ch, flag;

        if (sp->rx_dma.enable) {
                sprd_uart_dma_irq(port);
                return;
        }

        while ((serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK) &&
               max_count--) {
                lsr = serial_in(port, SPRD_LSR);
                ch = serial_in(port, SPRD_RXD);
                flag = TTY_NORMAL;
                port->icount.rx++;

                if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE |
                           SPRD_LSR_FE | SPRD_LSR_OE))
                        if (handle_lsr_errors(port, &flag, &lsr))
                                continue;
                if (uart_handle_sysrq_char(port, ch))
                        continue;

                uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
        }

        tty_flip_buffer_push(tty);
}

static inline void sprd_tx(struct uart_port *port)
{
        u8 ch;

        uart_port_tx_limited(port, ch, THLD_TX_EMPTY,
                true,
                serial_out(port, SPRD_TXD, ch),
                ({}));
}

/* this handles the interrupt from one port */
static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
{
        struct uart_port *port = dev_id;
        unsigned int ims;
        struct sprd_uart_port *sp =
                container_of(port, struct sprd_uart_port, port);

        uart_port_lock(port);

        ims = serial_in(port, SPRD_IMSR);

        if (!ims) {
                uart_port_unlock(port);
                return IRQ_NONE;
        }

        if (ims & sp->pdata->timeout_imsr)
                serial_out(port, SPRD_ICLR, sp->pdata->timeout_iclr);

        if (ims & SPRD_IMSR_BREAK_DETECT)
                serial_out(port, SPRD_ICLR, SPRD_IMSR_BREAK_DETECT);

        if (ims & (SPRD_IMSR_RX_FIFO_FULL | SPRD_IMSR_BREAK_DETECT |
                   sp->pdata->timeout_imsr))
                sprd_rx(port);

        if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
                sprd_tx(port);

        uart_port_unlock(port);

        return IRQ_HANDLED;
}

static void sprd_uart_dma_startup(struct uart_port *port,
                                  struct sprd_uart_port *sp)
{
        int ret;

        sprd_request_dma(port);
        if (!(sp->rx_dma.enable || sp->tx_dma.enable))
                return;

        ret = sprd_start_dma_rx(port);
        if (ret) {
                sp->rx_dma.enable = false;
                dma_release_channel(sp->rx_dma.chn);
                dev_warn(port->dev, "fail to start RX dma mode\n");
        }

        sprd_uart_dma_enable(port, true);
}

static int sprd_startup(struct uart_port *port)
{
        int ret = 0;
        unsigned int ien, fc;
        unsigned int timeout;
        struct sprd_uart_port *sp;
        unsigned long flags;

        serial_out(port, SPRD_CTL2,
                   THLD_TX_EMPTY << THLD_TX_EMPTY_SHIFT | THLD_RX_FULL);

        /* clear rx fifo */
        timeout = SPRD_TIMEOUT;
        while (timeout-- && serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK)
                serial_in(port, SPRD_RXD);

        /* clear tx fifo */
        timeout = SPRD_TIMEOUT;
        while (timeout-- && serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
                cpu_relax();

        /* clear interrupt */
        serial_out(port, SPRD_IEN, 0);
        serial_out(port, SPRD_ICLR, ~0);

        /* allocate irq */
        sp = container_of(port, struct sprd_uart_port, port);
        snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);

        sprd_uart_dma_startup(port, sp);

        ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
                               IRQF_SHARED, sp->name, port);
        if (ret) {
                dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
                        port->irq, ret);
                return ret;
        }
        fc = serial_in(port, SPRD_CTL1);
        fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
        serial_out(port, SPRD_CTL1, fc);

        /* enable interrupt */
        uart_port_lock_irqsave(port, &flags);
        ien = serial_in(port, SPRD_IEN);
        ien |= SPRD_IEN_BREAK_DETECT | sp->pdata->timeout_ien;
        if (!sp->rx_dma.enable)
                ien |= SPRD_IEN_RX_FULL;
        serial_out(port, SPRD_IEN, ien);
        uart_port_unlock_irqrestore(port, flags);

        return 0;
}

static void sprd_shutdown(struct uart_port *port)
{
        sprd_release_dma(port);
        serial_out(port, SPRD_IEN, 0);
        serial_out(port, SPRD_ICLR, ~0);
        devm_free_irq(port->dev, port->irq, port);
}

static void sprd_set_termios(struct uart_port *port, struct ktermios *termios,
                             const struct ktermios *old)
{
        unsigned int baud, quot;
        unsigned int lcr = 0, fc;
        unsigned long flags;

        /* ask the core to calculate the divisor for us */
        baud = uart_get_baud_rate(port, termios, old, 0, SPRD_BAUD_IO_LIMIT);

        quot = port->uartclk / baud;

        /* set data length */
        switch (termios->c_cflag & CSIZE) {
        case CS5:
                lcr |= SPRD_LCR_DATA_LEN5;
                break;
        case CS6:
                lcr |= SPRD_LCR_DATA_LEN6;
                break;
        case CS7:
                lcr |= SPRD_LCR_DATA_LEN7;
                break;
        case CS8:
        default:
                lcr |= SPRD_LCR_DATA_LEN8;
                break;
        }

        /* calculate stop bits */
        lcr &= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
        if (termios->c_cflag & CSTOPB)
                lcr |= SPRD_LCR_STOP_2BIT;
        else
                lcr |= SPRD_LCR_STOP_1BIT;

        /* calculate parity */
        lcr &= ~SPRD_LCR_PARITY;
        termios->c_cflag &= ~CMSPAR;    /* no support mark/space */
        if (termios->c_cflag & PARENB) {
                lcr |= SPRD_LCR_PARITY_EN;
                if (termios->c_cflag & PARODD)
                        lcr |= SPRD_LCR_ODD_PAR;
                else
                        lcr |= SPRD_LCR_EVEN_PAR;
        }

        uart_port_lock_irqsave(port, &flags);

        /* update the per-port timeout */
        uart_update_timeout(port, termios->c_cflag, baud);

        port->read_status_mask = SPRD_LSR_OE;
        if (termios->c_iflag & INPCK)
                port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
        if (termios->c_iflag & (IGNBRK | BRKINT | PARMRK))
                port->read_status_mask |= SPRD_LSR_BI;

        /* characters to ignore */
        port->ignore_status_mask = 0;
        if (termios->c_iflag & IGNPAR)
                port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
        if (termios->c_iflag & IGNBRK) {
                port->ignore_status_mask |= SPRD_LSR_BI;
                /*
                 * If we're ignoring parity and break indicators,
                 * ignore overruns too (for real raw support).
                 */
                if (termios->c_iflag & IGNPAR)
                        port->ignore_status_mask |= SPRD_LSR_OE;
        }

        /* flow control */
        fc = serial_in(port, SPRD_CTL1);
        fc &= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
        if (termios->c_cflag & CRTSCTS) {
                fc |= RX_HW_FLOW_CTL_THLD;
                fc |= RX_HW_FLOW_CTL_EN;
                fc |= TX_HW_FLOW_CTL_EN;
        }

        /* clock divider bit0~bit15 */
        serial_out(port, SPRD_CLKD0, quot & SPRD_CLKD0_MASK);

        /* clock divider bit16~bit20 */
        serial_out(port, SPRD_CLKD1,
                   (quot & SPRD_CLKD1_MASK) >> SPRD_CLKD1_SHIFT);
        serial_out(port, SPRD_LCR, lcr);
        fc |= RX_TOUT_THLD_DEF | RX_HFC_THLD_DEF;
        serial_out(port, SPRD_CTL1, fc);

        uart_port_unlock_irqrestore(port, flags);

        /* Don't rewrite B0 */
        if (tty_termios_baud_rate(termios))
                tty_termios_encode_baud_rate(termios, baud, baud);
}

static const char *sprd_type(struct uart_port *port)
{
        return "SPX";
}

static void sprd_release_port(struct uart_port *port)
{
        /* nothing to do */
}

static int sprd_request_port(struct uart_port *port)
{
        return 0;
}

static void sprd_config_port(struct uart_port *port, int flags)
{
        if (flags & UART_CONFIG_TYPE)
                port->type = PORT_SPRD;
}

static int sprd_verify_port(struct uart_port *port, struct serial_struct *ser)
{
        if (ser->type != PORT_SPRD)
                return -EINVAL;
        if (port->irq != ser->irq)
                return -EINVAL;
        if (port->iotype != ser->io_type)
                return -EINVAL;
        return 0;
}

static void sprd_pm(struct uart_port *port, unsigned int state,
                unsigned int oldstate)
{
        struct sprd_uart_port *sup =
                container_of(port, struct sprd_uart_port, port);

        switch (state) {
        case UART_PM_STATE_ON:
                clk_prepare_enable(sup->clk);
                break;
        case UART_PM_STATE_OFF:
                clk_disable_unprepare(sup->clk);
                break;
        }
}

#ifdef CONFIG_CONSOLE_POLL
static int sprd_poll_init(struct uart_port *port)
{
        if (port->state->pm_state != UART_PM_STATE_ON) {
                sprd_pm(port, UART_PM_STATE_ON, 0);
                port->state->pm_state = UART_PM_STATE_ON;
        }

        return 0;
}

static int sprd_poll_get_char(struct uart_port *port)
{
        while (!(serial_in(port, SPRD_STS1) & SPRD_RX_FIFO_CNT_MASK))
                cpu_relax();

        return serial_in(port, SPRD_RXD);
}

static void sprd_poll_put_char(struct uart_port *port, unsigned char ch)
{
        while (serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
                cpu_relax();

        serial_out(port, SPRD_TXD, ch);
}
#endif

static const struct uart_ops serial_sprd_ops = {
        .tx_empty = sprd_tx_empty,
        .get_mctrl = sprd_get_mctrl,
        .set_mctrl = sprd_set_mctrl,
        .stop_tx = sprd_stop_tx,
        .start_tx = sprd_start_tx,
        .stop_rx = sprd_stop_rx,
        .break_ctl = sprd_break_ctl,
        .startup = sprd_startup,
        .shutdown = sprd_shutdown,
        .set_termios = sprd_set_termios,
        .type = sprd_type,
        .release_port = sprd_release_port,
        .request_port = sprd_request_port,
        .config_port = sprd_config_port,
        .verify_port = sprd_verify_port,
        .pm = sprd_pm,
#ifdef CONFIG_CONSOLE_POLL
        .poll_init      = sprd_poll_init,
        .poll_get_char  = sprd_poll_get_char,
        .poll_put_char  = sprd_poll_put_char,
#endif
};

#ifdef CONFIG_SERIAL_SPRD_CONSOLE
static void wait_for_xmitr(struct uart_port *port)
{
        unsigned int status, tmout = 10000;

        /* wait up to 10ms for the character(s) to be sent */
        do {
                status = serial_in(port, SPRD_STS1);
                if (--tmout == 0)
                        break;
                udelay(1);
        } while (status & SPRD_TX_FIFO_CNT_MASK);
}

static void sprd_console_putchar(struct uart_port *port, unsigned char ch)
{
        wait_for_xmitr(port);
        serial_out(port, SPRD_TXD, ch);
}

static void sprd_console_write(struct console *co, const char *s,
                               unsigned int count)
{
        struct uart_port *port = &sprd_port[co->index]->port;
        int locked = 1;
        unsigned long flags;

        if (port->sysrq)
                locked = 0;
        else if (oops_in_progress)
                locked = uart_port_trylock_irqsave(port, &flags);
        else
                uart_port_lock_irqsave(port, &flags);

        uart_console_write(port, s, count, sprd_console_putchar);

        /* wait for transmitter to become empty */
        wait_for_xmitr(port);

        if (locked)
                uart_port_unlock_irqrestore(port, flags);
}

static int sprd_console_setup(struct console *co, char *options)
{
        struct sprd_uart_port *sprd_uart_port;
        int baud = 115200;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';

        if (co->index >= UART_NR_MAX || co->index < 0)
                co->index = 0;

        sprd_uart_port = sprd_port[co->index];
        if (!sprd_uart_port || !sprd_uart_port->port.membase) {
                pr_info("serial port %d not yet initialized\n", co->index);
                return -ENODEV;
        }

        if (options)
                uart_parse_options(options, &baud, &parity, &bits, &flow);

        return uart_set_options(&sprd_uart_port->port, co, baud,
                                parity, bits, flow);
}

static struct uart_driver sprd_uart_driver;
static struct console sprd_console = {
        .name = SPRD_TTY_NAME,
        .write = sprd_console_write,
        .device = uart_console_device,
        .setup = sprd_console_setup,
        .flags = CON_PRINTBUFFER,
        .index = -1,
        .data = &sprd_uart_driver,
};

static int __init sprd_serial_console_init(void)
{
        register_console(&sprd_console);
        return 0;
}
console_initcall(sprd_serial_console_init);

#define SPRD_CONSOLE    (&sprd_console)

/* Support for earlycon */
static void sprd_putc(struct uart_port *port, unsigned char c)
{
        unsigned int timeout = SPRD_TIMEOUT;

        while (timeout-- &&
               !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
                cpu_relax();

        writeb(c, port->membase + SPRD_TXD);
}

static void sprd_early_write(struct console *con, const char *s, unsigned int n)
{
        struct earlycon_device *dev = con->data;

        uart_console_write(&dev->port, s, n, sprd_putc);
}

static int __init sprd_early_console_setup(struct earlycon_device *device,
                                           const char *opt)
{
        if (!device->port.membase)
                return -ENODEV;

        device->con->write = sprd_early_write;
        return 0;
}
OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
                    sprd_early_console_setup);

#else /* !CONFIG_SERIAL_SPRD_CONSOLE */
#define SPRD_CONSOLE            NULL
#endif

static struct uart_driver sprd_uart_driver = {
        .owner = THIS_MODULE,
        .driver_name = "sprd_serial",
        .dev_name = SPRD_TTY_NAME,
        .major = 0,
        .minor = 0,
        .nr = UART_NR_MAX,
        .cons = SPRD_CONSOLE,
};

static void sprd_remove(struct platform_device *dev)
{
        struct sprd_uart_port *sup = platform_get_drvdata(dev);

        if (sup) {
                uart_remove_one_port(&sprd_uart_driver, &sup->port);
                sprd_port[sup->port.line] = NULL;
                sprd_rx_free_buf(sup);
                sprd_ports_num--;
        }

        if (!sprd_ports_num)
                uart_unregister_driver(&sprd_uart_driver);
}

static bool sprd_uart_is_console(struct uart_port *uport)
{
        struct console *cons = sprd_uart_driver.cons;

        if ((cons && cons->index >= 0 && cons->index == uport->line) ||
            of_console_check(uport->dev->of_node, SPRD_TTY_NAME, uport->line))
                return true;

        return false;
}

static int sprd_clk_init(struct uart_port *uport)
{
        struct clk *clk_uart, *clk_parent;
        struct sprd_uart_port *u = container_of(uport, struct sprd_uart_port, port);

        clk_uart = devm_clk_get(uport->dev, "uart");
        if (IS_ERR(clk_uart)) {
                if (PTR_ERR(clk_uart) == -EPROBE_DEFER)
                        return -EPROBE_DEFER;

                dev_warn(uport->dev, "uart%d can't get uart clock\n",
                         uport->line);
                clk_uart = NULL;
        }

        clk_parent = devm_clk_get(uport->dev, "source");
        if (IS_ERR(clk_parent)) {
                if (PTR_ERR(clk_parent) == -EPROBE_DEFER)
                        return -EPROBE_DEFER;

                dev_warn(uport->dev, "uart%d can't get source clock\n",
                         uport->line);
                clk_parent = NULL;
        }

        if (!clk_uart || clk_set_parent(clk_uart, clk_parent))
                uport->uartclk = SPRD_DEFAULT_SOURCE_CLK;
        else
                uport->uartclk = clk_get_rate(clk_uart);

        u->clk = devm_clk_get(uport->dev, "enable");
        if (IS_ERR(u->clk)) {
                if (PTR_ERR(u->clk) == -EPROBE_DEFER)
                        return -EPROBE_DEFER;

                dev_warn(uport->dev, "uart%d can't get enable clock\n",
                        uport->line);

                /* To keep console alive even if the error occurred */
                if (!sprd_uart_is_console(uport))
                        return PTR_ERR(u->clk);

                u->clk = NULL;
        }

        return 0;
}

static int sprd_probe(struct platform_device *pdev)
{
        struct resource *res;
        struct uart_port *up;
        struct sprd_uart_port *sport;
        int irq;
        int index;
        int ret;

        index = of_alias_get_id(pdev->dev.of_node, "serial");
        if (index < 0 || index >= UART_NR_MAX) {
                dev_err(&pdev->dev, "got a wrong serial alias id %d\n", index);
                return -EINVAL;
        }

        sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
        if (!sport)
                return -ENOMEM;

        up = &sport->port;
        up->dev = &pdev->dev;
        up->line = index;
        up->type = PORT_SPRD;
        up->iotype = UPIO_MEM;
        up->uartclk = SPRD_DEF_RATE;
        up->fifosize = SPRD_FIFO_SIZE;
        up->ops = &serial_sprd_ops;
        up->flags = UPF_BOOT_AUTOCONF;
        up->has_sysrq = IS_ENABLED(CONFIG_SERIAL_SPRD_CONSOLE);

        ret = sprd_clk_init(up);
        if (ret)
                return ret;

        up->membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res);
        if (IS_ERR(up->membase))
                return PTR_ERR(up->membase);

        up->mapbase = res->start;

        sport->pdata = of_device_get_match_data(&pdev->dev);
        if (!sport->pdata) {
                dev_err(&pdev->dev, "get match data failed!\n");
                return -EINVAL;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;
        up->irq = irq;

        /*
         * Allocate one dma buffer to prepare for receive transfer, in case
         * memory allocation failure at runtime.
         */
        ret = sprd_rx_alloc_buf(sport);
        if (ret)
                return ret;

        if (!sprd_ports_num) {
                ret = uart_register_driver(&sprd_uart_driver);
                if (ret < 0) {
                        pr_err("Failed to register SPRD-UART driver\n");
                        goto free_rx_buf;
                }
        }

        sprd_ports_num++;
        sprd_port[index] = sport;

        ret = uart_add_one_port(&sprd_uart_driver, up);
        if (ret)
                goto clean_port;

        platform_set_drvdata(pdev, up);

        return 0;

clean_port:
        sprd_port[index] = NULL;
        if (--sprd_ports_num == 0)
                uart_unregister_driver(&sprd_uart_driver);
free_rx_buf:
        sprd_rx_free_buf(sport);
        return ret;
}

#ifdef CONFIG_PM_SLEEP
static int sprd_suspend(struct device *dev)
{
        struct sprd_uart_port *sup = dev_get_drvdata(dev);

        uart_suspend_port(&sprd_uart_driver, &sup->port);

        return 0;
}

static int sprd_resume(struct device *dev)
{
        struct sprd_uart_port *sup = dev_get_drvdata(dev);

        uart_resume_port(&sprd_uart_driver, &sup->port);

        return 0;
}
#endif

static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);

static const struct of_device_id serial_ids[] = {
        {.compatible = "sprd,sc9836-uart", .data = &sc9836_data},
        {.compatible = "sprd,sc9632-uart", .data = &sc9632_data},
        {}
};
MODULE_DEVICE_TABLE(of, serial_ids);

static struct platform_driver sprd_platform_driver = {
        .probe          = sprd_probe,
        .remove         = sprd_remove,
        .driver         = {
                .name   = "sprd_serial",
                .of_match_table = serial_ids,
                .pm     = &sprd_pm_ops,
        },
};

module_platform_driver(sprd_platform_driver);

MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");