/*
   * serial_tegra.c
   *
   * High-speed serial driver for NVIDIA Tegra SoCs
   *
   * Copyright (c) 2012-2013, NVIDIA CORPORATION.  All rights reserved.
   *
   * Author: Laxman Dewangan <ldewangan@nvidia.com>
   *
   * This program is free software; you can redistribute it and/or modify it
   * under the terms and conditions of the GNU General Public License,
   * version 2, as published by the Free Software Foundation.
   *
   * This program is distributed in the hope it will be useful, but WITHOUT
   * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
   * more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.  If not, see <http://www.gnu.org/licenses/>.
   */
  
  #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/of_device.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			5
  
  /* 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
  
  /**
   * 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.
   */
  struct tegra_uart_chip_data {
  	bool	tx_fifo_full_status;
  	bool	allow_txfifo_reset_fifo_mode;
  	bool	support_clk_src_div;
  };
  
  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;
  	int					tx_bytes_requested;
  	int					rx_bytes_requested;
  };
  
  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 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;
  	}
  	return;
  }
  
  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;
  	}
  	return;
  }
  
  static void tegra_uart_set_mctrl(struct uart_port *u, unsigned int mctrl)
  {
  	struct tegra_uart_port *tup = to_tegra_uport(u);
  	unsigned long mcr;
  	int dtr_enable;
  
  	mcr = tup->mcr_shadow;
  	tup->rts_active = !!(mctrl & TIOCM_RTS);
  	set_rts(tup, tup->rts_active);
  
  	dtr_enable = !!(mctrl & TIOCM_DTR);
  	set_dtr(tup, dtr_enable);
  	return;
  }
  
  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;
  }
  
  /* 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 void tegra_uart_fifo_reset(struct tegra_uart_port *tup, u8 fcr_bits)
  {
  	unsigned long fcr = tup->fcr_shadow;
  
  	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);
  	}
  
  	/* Dummy read to ensure the write is posted */
  	tegra_uart_read(tup, UART_SCR);
  
  	/* Wait for the flush to propagate. */
  	tegra_uart_wait_sym_time(tup, 1);
  }
  
  static int tegra_set_baudrate(struct tegra_uart_port *tup, unsigned int baud)
  {
  	unsigned long rate;
  	unsigned int divisor;
  	unsigned long lcr;
  	int ret;
  
  	if (tup->current_baud == baud)
  		return 0;
  
  	if (tup->cdata->support_clk_src_div) {
  		rate = baud * 16;
  		ret = clk_set_rate(tup->uart_clk, rate);
  		if (ret < 0) {
  			dev_err(tup->uport.dev,
  				"clk_set_rate() failed for rate %lu
  ", rate);
  			return ret;
  		}
  		divisor = 1;
  	} else {
  		rate = clk_get_rate(tup->uart_clk);
  		divisor = DIV_ROUND_CLOSEST(rate, baud * 16);
  	}
  
  	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);
  
  	tup->current_baud = baud;
  
  	/* wait two character intervals at new rate */
  	tegra_uart_wait_sym_time(tup, 2);
  	return 0;
  }
  
  static char tegra_uart_decode_rx_error(struct tegra_uart_port *tup,
  			unsigned long lsr)
  {
  	char flag = TTY_NORMAL;
  
  	if (unlikely(lsr & TEGRA_UART_LSR_ANY)) {
  		if (lsr & UART_LSR_OE) {
  			/* Overrrun error */
  			flag |= TTY_OVERRUN;
  			tup->uport.icount.overrun++;
  			dev_err(tup->uport.dev, "Got overrun errors
  ");
  		} else if (lsr & UART_LSR_PE) {
  			/* Parity error */
  			flag |= TTY_PARITY;
  			tup->uport.icount.parity++;
  			dev_err(tup->uport.dev, "Got Parity errors
  ");
  		} else if (lsr & UART_LSR_FE) {
  			flag |= TTY_FRAME;
  			tup->uport.icount.frame++;
  			dev_err(tup->uport.dev, "Got frame errors
  ");
  		} else if (lsr & UART_LSR_BI) {
  			dev_err(tup->uport.dev, "Got Break
  ");
  			tup->uport.icount.brk++;
  			/* 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);
  		}
  	}
  	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)
  {
  	struct circ_buf *xmit = &tup->uport.state->xmit;
  	int i;
  
  	for (i = 0; i < max_bytes; i++) {
  		BUG_ON(uart_circ_empty(xmit));
  		if (tup->cdata->tx_fifo_full_status) {
  			unsigned long lsr = tegra_uart_read(tup, UART_LSR);
  			if ((lsr & TEGRA_UART_LSR_TXFIFO_FULL))
  				break;
  		}
  		tegra_uart_write(tup, xmit->buf[xmit->tail], UART_TX);
  		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
  		tup->uport.icount.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 circ_buf *xmit = &tup->uport.state->xmit;
  	struct dma_tx_state state;
  	unsigned long flags;
  	int count;
  
  	dmaengine_tx_status(tup->tx_dma_chan, tup->rx_cookie, &state);
  	count = tup->tx_bytes_requested - state.residue;
  	async_tx_ack(tup->tx_dma_desc);
  	spin_lock_irqsave(&tup->uport.lock, flags);
  	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
  	tup->tx_in_progress = 0;
  	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
  		uart_write_wakeup(&tup->uport);
  	tegra_uart_start_next_tx(tup);
  	spin_unlock_irqrestore(&tup->uport.lock, flags);
  }
  
  static int tegra_uart_start_tx_dma(struct tegra_uart_port *tup,
  		unsigned long count)
  {
  	struct circ_buf *xmit = &tup->uport.state->xmit;
  	dma_addr_t tx_phys_addr;
  
  	dma_sync_single_for_device(tup->uport.dev, tup->tx_dma_buf_phys,
  				UART_XMIT_SIZE, DMA_TO_DEVICE);
  
  	tup->tx_bytes = count & ~(0xF);
  	tx_phys_addr = tup->tx_dma_buf_phys + xmit->tail;
  	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
  ");
  		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)
  {
  	unsigned long tail;
  	unsigned long count;
  	struct circ_buf *xmit = &tup->uport.state->xmit;
  
  	tail = (unsigned long)&xmit->buf[xmit->tail];
  	count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
  	if (!count)
  		return;
  
  	if (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 circ_buf *xmit = &u->state->xmit;
  
  	if (!uart_circ_empty(xmit) && !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;
  
  	spin_lock_irqsave(&u->lock, 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;
  	}
  	spin_unlock_irqrestore(&u->lock, flags);
  	return ret;
  }
  
  static void tegra_uart_stop_tx(struct uart_port *u)
  {
  	struct tegra_uart_port *tup = to_tegra_uport(u);
  	struct circ_buf *xmit = &tup->uport.state->xmit;
  	struct dma_tx_state state;
  	int count;
  
  	dmaengine_terminate_all(tup->tx_dma_chan);
  	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);
  	xmit->tail = (xmit->tail + count) & (UART_XMIT_SIZE - 1);
  	tup->tx_in_progress = 0;
  	return;
  }
  
  static void tegra_uart_handle_tx_pio(struct tegra_uart_port *tup)
  {
  	struct circ_buf *xmit = &tup->uport.state->xmit;
  
  	tegra_uart_fill_tx_fifo(tup, tup->tx_bytes);
  	tup->tx_in_progress = 0;
  	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
  		uart_write_wakeup(&tup->uport);
  	tegra_uart_start_next_tx(tup);
  	return;
  }
  
  static void tegra_uart_handle_rx_pio(struct tegra_uart_port *tup,
  		struct tty_port *tty)
  {
  	do {
  		char flag = TTY_NORMAL;
  		unsigned long lsr = 0;
  		unsigned char ch;
  
  		lsr = tegra_uart_read(tup, UART_LSR);
  		if (!(lsr & UART_LSR_DR))
  			break;
  
  		flag = tegra_uart_decode_rx_error(tup, lsr);
  		ch = (unsigned char) tegra_uart_read(tup, UART_RX);
  		tup->uport.icount.rx++;
  
  		if (!uart_handle_sysrq_char(&tup->uport, ch) && tty)
  			tty_insert_flip_char(tty, ch, flag);
  	} while (1);
  
  	return;
  }
  
  static void tegra_uart_copy_rx_to_tty(struct tegra_uart_port *tup,
  		struct tty_port *tty, int count)
  {
  	int copied;
  
  	tup->uport.icount.rx += count;
  	if (!tty) {
  		dev_err(tup->uport.dev, "No tty port
  ");
  		return;
  	}
  	dma_sync_single_for_cpu(tup->uport.dev, tup->rx_dma_buf_phys,
  				TEGRA_UART_RX_DMA_BUFFER_SIZE, DMA_FROM_DEVICE);
  	copied = tty_insert_flip_string(tty,
  			((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
  ");
  	}
  	dma_sync_single_for_device(tup->uport.dev, tup->rx_dma_buf_phys,
  				TEGRA_UART_RX_DMA_BUFFER_SIZE, DMA_TO_DEVICE);
  }
  
  static void tegra_uart_rx_dma_complete(void *args)
  {
  	struct tegra_uart_port *tup = args;
  	struct uart_port *u = &tup->uport;
  	int count = tup->rx_bytes_requested;
  	struct tty_struct *tty = tty_port_tty_get(&tup->uport.state->port);
  	struct tty_port *port = &u->state->port;
  	unsigned long flags;
  
  	async_tx_ack(tup->rx_dma_desc);
  	spin_lock_irqsave(&u->lock, flags);
  
  	/* Deactivate flow control to stop sender */
  	if (tup->rts_active)
  		set_rts(tup, false);
  
  	/* If we are here, DMA is stopped */
  	if (count)
  		tegra_uart_copy_rx_to_tty(tup, port, count);
  
  	tegra_uart_handle_rx_pio(tup, port);
  	if (tty) {
  		spin_unlock_irqrestore(&u->lock, flags);
  		tty_flip_buffer_push(port);
  		spin_lock_irqsave(&u->lock, flags);
  		tty_kref_put(tty);
  	}
  	tegra_uart_start_rx_dma(tup);
  
  	/* Activate flow control to start transfer */
  	if (tup->rts_active)
  		set_rts(tup, true);
  
  	spin_unlock_irqrestore(&u->lock, flags);
  }
  
  static void tegra_uart_handle_rx_dma(struct tegra_uart_port *tup,
  		unsigned long *flags)
  {
  	struct dma_tx_state state;
  	struct tty_struct *tty = tty_port_tty_get(&tup->uport.state->port);
  	struct tty_port *port = &tup->uport.state->port;
  	struct uart_port *u = &tup->uport;
  	int count;
  
  	/* Deactivate flow control to stop sender */
  	if (tup->rts_active)
  		set_rts(tup, false);
  
  	dmaengine_terminate_all(tup->rx_dma_chan);
  	dmaengine_tx_status(tup->rx_dma_chan,  tup->rx_cookie, &state);
  	count = tup->rx_bytes_requested - state.residue;
  
  	/* If we are here, DMA is stopped */
  	if (count)
  		tegra_uart_copy_rx_to_tty(tup, port, count);
  
  	tegra_uart_handle_rx_pio(tup, port);
  	if (tty) {
  		spin_unlock_irqrestore(&u->lock, *flags);
  		tty_flip_buffer_push(port);
  		spin_lock_irqsave(&u->lock, *flags);
  		tty_kref_put(tty);
  	}
  	tegra_uart_start_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;
  
  	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
  ");
  		return -EIO;
  	}
  
  	tup->rx_dma_desc->callback = tegra_uart_rx_dma_complete;
  	tup->rx_dma_desc->callback_param = tup;
  	dma_sync_single_for_device(tup->uport.dev, tup->rx_dma_buf_phys,
  				count, DMA_TO_DEVICE);
  	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);
  	return;
  }
  
  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_int = false;
  	unsigned long flags;
  
  	spin_lock_irqsave(&u->lock, flags);
  	while (1) {
  		iir = tegra_uart_read(tup, UART_IIR);
  		if (iir & UART_IIR_NO_INT) {
  			if (is_rx_int) {
  				tegra_uart_handle_rx_dma(tup, &flags);
  				if (tup->rx_in_progress) {
  					ier = tup->ier_shadow;
  					ier |= (UART_IER_RLSI | UART_IER_RTOIE |
  						TEGRA_UART_IER_EORD);
  					tup->ier_shadow = ier;
  					tegra_uart_write(tup, ier, UART_IER);
  				}
  			}
  			spin_unlock_irqrestore(&u->lock, 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 */
  		case 2: /* Receive */
  			if (!is_rx_int) {
  				is_rx_int = true;
  				/* Disable Rx interrupts */
  				ier = tup->ier_shadow;
  				ier |= UART_IER_RDI;
  				tegra_uart_write(tup, ier, UART_IER);
  				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;
  
  		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_struct *tty;
  	struct tty_port *port = &u->state->port;
  	struct dma_tx_state state;
  	unsigned long ier;
  	int count;
  
  	if (tup->rts_active)
  		set_rts(tup, false);
  
  	if (!tup->rx_in_progress)
  		return;
  
  	tty = tty_port_tty_get(&tup->uport.state->port);
  
  	tegra_uart_wait_sym_time(tup, 1); /* wait a 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->rx_dma_chan) {
  		dmaengine_terminate_all(tup->rx_dma_chan);
  		dmaengine_tx_status(tup->rx_dma_chan, tup->rx_cookie, &state);
  		async_tx_ack(tup->rx_dma_desc);
  		count = tup->rx_bytes_requested - state.residue;
  		tegra_uart_copy_rx_to_tty(tup, port, count);
  		tegra_uart_handle_rx_pio(tup, port);
  	} else {
  		tegra_uart_handle_rx_pio(tup, port);
  	}
  	if (tty) {
  		tty_flip_buffer_push(port);
  		tty_kref_put(tty);
  	}
  	return;
  }
  
  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
  ");
  
  		/* 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
  ");
  				break;
  			}
  			lsr = tegra_uart_read(tup, UART_LSR);
  		}
  	}
  
  	spin_lock_irqsave(&tup->uport.lock, flags);
  	/* Reset the Rx and Tx FIFOs */
  	tegra_uart_fifo_reset(tup, UART_FCR_CLEAR_XMIT | UART_FCR_CLEAR_RCVR);
  	tup->current_baud = 0;
  	spin_unlock_irqrestore(&tup->uport.lock, flags);
  
  	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;
  
  	clk_prepare_enable(tup->uart_clk);
  
  	/* 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;
  	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);
  
  	/*
  	 * Initialize the UART with default configuration
  	 * (115200, N, 8, 1) so that the receive DMA buffer may be
  	 * enqueued
  	 */
  	tup->lcr_shadow = TEGRA_UART_DEFAULT_LSR;
  	tegra_set_baudrate(tup, TEGRA_UART_DEFAULT_BAUD);
  	tup->fcr_shadow |= UART_FCR_DMA_SELECT;
  	tegra_uart_write(tup, tup->fcr_shadow, UART_FCR);
  
  	ret = tegra_uart_start_rx_dma(tup);
  	if (ret < 0) {
  		dev_err(tup->uport.dev, "Not able to start Rx DMA
  ");
  		return ret;
  	}
  	tup->rx_in_progress = 1;
  
  	/*
  	 * Enable IE_RXS for the receive status interrupts like line errros.
  	 * Enable IE_RX_TIMEOUT to get the bytes which cannot be DMA'd.
  	 *
  	 * If using DMA mode, enable EORD instead of receive interrupt which
  	 * will interrupt after the UART is done with the receive instead of
  	 * the interrupt when the FIFO "threshold" is reached.
  	 *
  	 * 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 | TEGRA_UART_IER_EORD;
  	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
  	return 0;
  }
  
  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_slave_channel_reason(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
  ", 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
  ");
  			dma_release_channel(dma_chan);
  			return -ENOMEM;
  		}
  	} else {
  		dma_phys = dma_map_single(tup->uport.dev,
  			tup->uport.state->xmit.buf, UART_XMIT_SIZE,
  			DMA_TO_DEVICE);
  		dma_buf = tup->uport.state->xmit.buf;
  	}
  
  	if (dma_to_memory) {
  		dma_sconfig.src_addr = tup->uport.mapbase;
  		dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
  		dma_sconfig.src_maxburst = 4;
  	} else {
  		dma_sconfig.dst_addr = tup->uport.mapbase;
  		dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
  		dma_sconfig.dst_maxburst = 16;
  	}
  
  	ret = dmaengine_slave_config(dma_chan, &dma_sconfig);
  	if (ret < 0) {
  		dev_err(tup->uport.dev,
  			"Dma slave config failed, err = %d
  ", ret);
  		goto scrub;
  	}
  
  	if (dma_to_memory) {
  		tup->rx_dma_chan = dma_chan;
  		tup->rx_dma_buf_virt = dma_buf;
  		tup->rx_dma_buf_phys = dma_phys;
  	} else {
  		tup->tx_dma_chan = dma_chan;
  		tup->tx_dma_buf_virt = dma_buf;
  		tup->tx_dma_buf_phys = dma_phys;
  	}
  	return 0;
  
  scrub:
  	dma_release_channel(dma_chan);
  	return ret;
  }
  
  static void tegra_uart_dma_channel_free(struct tegra_uart_port *tup,
  		bool dma_to_memory)
  {
  	struct dma_chan *dma_chan;
  
  	if (dma_to_memory) {
  		dma_free_coherent(tup->uport.dev, TEGRA_UART_RX_DMA_BUFFER_SIZE,
  				tup->rx_dma_buf_virt, tup->rx_dma_buf_phys);
  		dma_chan = tup->rx_dma_chan;
  		tup->rx_dma_chan = NULL;
  		tup->rx_dma_buf_phys = 0;
  		tup->rx_dma_buf_virt = NULL;
  	} else {
  		dma_unmap_single(tup->uport.dev, tup->tx_dma_buf_phys,
  			UART_XMIT_SIZE, DMA_TO_DEVICE);
  		dma_chan = tup->tx_dma_chan;
  		tup->tx_dma_chan = NULL;
  		tup->tx_dma_buf_phys = 0;
  		tup->tx_dma_buf_virt = NULL;
  	}
  	dma_release_channel(dma_chan);
  }
  
  static int tegra_uart_startup(struct uart_port *u)
  {
  	struct tegra_uart_port *tup = to_tegra_uport(u);
  	int ret;
  
  	ret = tegra_uart_dma_channel_allocate(tup, false);
  	if (ret < 0) {
  		dev_err(u->dev, "Tx Dma allocation failed, err = %d
  ", ret);
  		return ret;
  	}
  
  	ret = tegra_uart_dma_channel_allocate(tup, true);
  	if (ret < 0) {
  		dev_err(u->dev, "Rx Dma allocation failed, err = %d
  ", ret);
  		goto fail_rx_dma;
  	}
  
  	ret = tegra_uart_hw_init(tup);
  	if (ret < 0) {
  		dev_err(u->dev, "Uart HW init failed, err = %d
  ", 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
  ", u->irq);
  		goto fail_hw_init;
  	}
  	return 0;
  
  fail_hw_init:
  	tegra_uart_dma_channel_free(tup, true);
  fail_rx_dma:
  	tegra_uart_dma_channel_free(tup, false);
  	return ret;
  }
  
  static void tegra_uart_shutdown(struct uart_port *u)
  {
  	struct tegra_uart_port *tup = to_tegra_uport(u);
  
  	tegra_uart_hw_deinit(tup);
  
  	tup->rx_in_progress = 0;
  	tup->tx_in_progress = 0;
  
  	tegra_uart_dma_channel_free(tup, true);
  	tegra_uart_dma_channel_free(tup, false);
  	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, struct ktermios *oldtermios)
  {
  	struct tegra_uart_port *tup = to_tegra_uport(u);
  	unsigned int baud;
  	unsigned long flags;
  	unsigned int lcr;
  	int symb_bit = 1;
  	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;
  
  	max_divider *= 16;
  	spin_lock_irqsave(&u->lock, 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 change */
  	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) {
  		symb_bit++;
  		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;
  		}
  	}
  
  	lcr &= ~UART_LCR_WLEN8;
  	switch (termios->c_cflag & CSIZE) {
  	case CS5:
  		lcr |= UART_LCR_WLEN5;
  		symb_bit += 5;
  		break;
  	case CS6:
  		lcr |= UART_LCR_WLEN6;
  		symb_bit += 6;
  		break;
  	case CS7:
  		lcr |= UART_LCR_WLEN7;
  		symb_bit += 7;
  		break;
  	default:
  		lcr |= UART_LCR_WLEN8;
  		symb_bit += 8;
  		break;
  	}
  
  	/* Stop bits */
  	if (termios->c_cflag & CSTOPB) {
  		lcr |= UART_LCR_STOP;
  		symb_bit += 2;
  	} else {
  		lcr &= ~UART_LCR_STOP;
  		symb_bit++;
  	}
  
  	tegra_uart_write(tup, lcr, UART_LCR);
  	tup->lcr_shadow = lcr;
  	tup->symb_bit = symb_bit;
  
  	/* Baud rate. */
  	baud = uart_get_baud_rate(u, termios, oldtermios,
  			parent_clk_rate/max_divider,
  			parent_clk_rate/16);
  	spin_unlock_irqrestore(&u->lock, flags);
  	tegra_set_baudrate(tup, baud);
  	if (tty_termios_baud_rate(termios))
  		tty_termios_encode_baud_rate(termios, baud, baud);
  	spin_lock_irqsave(&u->lock, 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 write has completed */
  	tegra_uart_read(tup, UART_IER);
  
  	/* Reenable interrupt */
  	tegra_uart_write(tup, tup->ier_shadow, UART_IER);
  	tegra_uart_read(tup, UART_IER);
  
  	spin_unlock_irqrestore(&u->lock, flags);
  	return;
  }
  
  /*
   * 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);
  	return;
  }
  
  static const char *tegra_uart_type(struct uart_port *u)
  {
  	return TEGRA_UART_TYPE;
  }
  
  static 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;
  
  	port = of_alias_get_id(np, "serial");
  	if (port < 0) {
  		dev_err(&pdev->dev, "failed to get alias id, errno %d
  ", port);
  		return port;
  	}
  	tup->uport.line = port;
  
  	tup->enable_modem_interrupt = of_property_read_bool(np,
  					"nvidia,enable-modem-interrupt");
  	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,
  };
  
  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,
  };
  
  static 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,
  	}, {
  	},
  };
  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;
  	const struct of_device_id *match;
  
  	match = of_match_device(tegra_uart_of_match, &pdev->dev);
  	if (!match) {
  		dev_err(&pdev->dev, "Error: No device match found
  ");
  		return -ENODEV;
  	}
  	cdata = match->data;
  
  	tup = devm_kzalloc(&pdev->dev, sizeof(*tup), GFP_KERNEL);
  	if (!tup) {
  		dev_err(&pdev->dev, "Failed to allocate memory for tup
  ");
  		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);
  	resource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  	if (!resource) {
  		dev_err(&pdev->dev, "No IO memory resource
  ");
  		return -ENODEV;
  	}
  
  	u->mapbase = resource->start;
  	u->membase = devm_ioremap_resource(&pdev->dev, resource);
  	if (IS_ERR(u->membase))
  		return PTR_ERR(u->membase);
  
  	tup->uart_clk = devm_clk_get(&pdev->dev, NULL);
  	if (IS_ERR(tup->uart_clk)) {
  		dev_err(&pdev->dev, "Couldn't get the clock
  ");
  		return PTR_ERR(tup->uart_clk);
  	}
  
  	tup->rst = devm_reset_control_get(&pdev->dev, "serial");
  	if (IS_ERR(tup->rst)) {
  		dev_err(&pdev->dev, "Couldn't get the reset
  ");
  		return PTR_ERR(tup->rst);
  	}
  
  	u->iotype = UPIO_MEM32;
  	u->irq = platform_get_irq(pdev, 0);
  	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
  ", ret);
  		return ret;
  	}
  	return ret;
  }
  
  static int 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);
  	return 0;
  }
  
  #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;
  
  	ret = uart_register_driver(&tegra_uart_driver);
  	if (ret < 0) {
  		pr_err("Could not register %s driver
  ",
  			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
  ", ret);
  		uart_unregister_driver(&tegra_uart_driver);
  		return ret;
  	}
  	return 0;
  }
  
  static void __exit tegra_uart_exit(void)
  {
  	pr_info("Unloading tegra uart driver
  ");
  	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");