drivers/serial/bfin_sport_uart.c - kernel/msm - Gitiles

 /*
  * File:	linux/drivers/serial/bfin_sport_uart.c
  *
  * Based on:	drivers/serial/bfin_5xx.c by Aubrey Li.
  * Author:	Roy Huang <roy.huang@analog.com>
  *
  * Created:	Nov 22, 2006
  * Copyright:	(c) 2006-2007 Analog Devices Inc.
  * Description: this driver enable SPORTs on Blackfin emulate UART.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that 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 the file COPYING, or write
  * to the Free Software Foundation, Inc.,
  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */

 /*
  * This driver and the hardware supported are in term of EE-191 of ADI.
  * http://www.analog.com/UploadedFiles/Application_Notes/399447663EE191.pdf
  * This application note describe how to implement a UART on a Sharc DSP,
  * but this driver is implemented on Blackfin Processor.
  */

 /* After reset, there is a prelude of low level pulse when transmit data first
  * time. No addtional pulse in following transmit.
  * According to document:
  * The SPORTs are ready to start transmitting or receiving data no later than
  * three serial clock cycles after they are enabled in the SPORTx_TCR1 or
  * SPORTx_RCR1 register. No serial clock cycles are lost from this point on.
  * The first internal frame sync will occur one frame sync delay after the
  * SPORTs are ready. External frame syncs can occur as soon as the SPORT is
  * ready.
  */

 /* Thanks to Axel Alatalo <axel@rubico.se> for fixing sport rx bug. Sometimes
  * sport receives data incorrectly. The following is Axel's words.
  * As EE-191, sport rx samples 3 times of the UART baudrate and takes the
  * middle smaple of every 3 samples as the data bit. For a 8-N-1 UART setting,
  * 30 samples will be required for a byte. If transmitter sends a 1/3 bit short
  * byte due to buadrate drift, then the 30th sample of a byte, this sample is
  * also the third sample of the stop bit, will happens on the immediately
  * following start bit which will be thrown away and missed. Thus since parts
  * of the startbit will be missed and the receiver will begin to drift, the
  * effect accumulates over time until synchronization is lost.
  * If only require 2 samples of the stopbit (by sampling in total 29 samples),
  * then a to short byte as in the case above will be tolerated. Then the 1/3
  * early startbit will trigger a framesync since the last read is complete
  * after only 2/3 stopbit and framesync is active during the last 1/3 looking
  * for a possible early startbit. */

 //#define DEBUG

 #include <linux/module.h>
 #include <linux/ioport.h>
 #include <linux/init.h>
 #include <linux/console.h>
 #include <linux/sysrq.h>
 #include <linux/platform_device.h>
 #include <linux/tty.h>
 #include <linux/tty_flip.h>
 #include <linux/serial_core.h>

 #include <asm/delay.h>
 #include <asm/portmux.h>

 #include "bfin_sport_uart.h"

 unsigned short bfin_uart_pin_req_sport0[] =
 	{P_SPORT0_TFS, P_SPORT0_DTPRI, P_SPORT0_TSCLK, P_SPORT0_RFS, \
 	 P_SPORT0_DRPRI, P_SPORT0_RSCLK, P_SPORT0_DRSEC, P_SPORT0_DTSEC, 0};

 unsigned short bfin_uart_pin_req_sport1[] =
 	{P_SPORT1_TFS, P_SPORT1_DTPRI, P_SPORT1_TSCLK, P_SPORT1_RFS, \
 	P_SPORT1_DRPRI, P_SPORT1_RSCLK, P_SPORT1_DRSEC, P_SPORT1_DTSEC, 0};

 #define DRV_NAME "bfin-sport-uart"

 struct sport_uart_port {
 	struct uart_port	port;
 	char			*name;

 	int			tx_irq;
 	int			rx_irq;
 	int			err_irq;
 };

 static void sport_uart_tx_chars(struct sport_uart_port *up);
 static void sport_stop_tx(struct uart_port *port);

 static inline void tx_one_byte(struct sport_uart_port *up, unsigned int value)
 {
 	pr_debug("%s value:%x\n", __FUNCTION__, value);
 	/* Place a Start and Stop bit */
 	__asm__ volatile (
 		"R2 = b#01111111100;\n\t"
 		"R3 = b#10000000001;\n\t"
 		"%0 <<= 2;\n\t"
 		"%0 = %0 & R2;\n\t"
 		"%0 = %0 | R3;\n\t"
 		:"=r"(value)
 		:"0"(value)
 		:"R2", "R3");
 	pr_debug("%s value:%x\n", __FUNCTION__, value);

 	SPORT_PUT_TX(up, value);
 }

 static inline unsigned int rx_one_byte(struct sport_uart_port *up)
 {
 	unsigned int value, extract;

 	value = SPORT_GET_RX32(up);
 	pr_debug("%s value:%x\n", __FUNCTION__, value);

 	/* Extract 8 bits data */
 	__asm__ volatile (
 		"R5 = 0;\n\t"
 		"P0 = 8;\n\t"
 		"R1 = 0x1801(Z);\n\t"
 		"R3 = 0x0300(Z);\n\t"
 		"R4 = 0;\n\t"
 		"LSETUP(loop_s, loop_e) LC0 = P0;\nloop_s:\t"
 		"R2 = extract(%1, R1.L)(Z);\n\t"
 		"R2 <<= R4;\n\t"
 		"R5 = R5 | R2;\n\t"
 		"R1 = R1 - R3;\nloop_e:\t"
 		"R4 += 1;\n\t"
 		"%0 = R5;\n\t"
 		:"=r"(extract)
 		:"r"(value)
 		:"P0", "R1", "R2","R3","R4", "R5");

 	pr_debug("	extract:%x\n", extract);
 	return extract;
 }

 static int sport_uart_setup(struct sport_uart_port *up, int sclk, int baud_rate)
 {
 	int tclkdiv, tfsdiv, rclkdiv;

 	/* Set TCR1 and TCR2 */
 	SPORT_PUT_TCR1(up, (LTFS | ITFS | TFSR | TLSBIT | ITCLK));
 	SPORT_PUT_TCR2(up, 10);
 	pr_debug("%s TCR1:%x, TCR2:%x\n", __FUNCTION__, SPORT_GET_TCR1(up), SPORT_GET_TCR2(up));

 	/* Set RCR1 and RCR2 */
 	SPORT_PUT_RCR1(up, (RCKFE | LARFS | LRFS | RFSR | IRCLK));
 	SPORT_PUT_RCR2(up, 28);
 	pr_debug("%s RCR1:%x, RCR2:%x\n", __FUNCTION__, SPORT_GET_RCR1(up), SPORT_GET_RCR2(up));

 	tclkdiv = sclk/(2 * baud_rate) - 1;
 	tfsdiv = 12;
 	rclkdiv = sclk/(2 * baud_rate * 3) - 1;
 	SPORT_PUT_TCLKDIV(up, tclkdiv);
 	SPORT_PUT_TFSDIV(up, tfsdiv);
 	SPORT_PUT_RCLKDIV(up, rclkdiv);
 	SSYNC();
 	pr_debug("%s sclk:%d, baud_rate:%d, tclkdiv:%d, tfsdiv:%d, rclkdiv:%d\n",
 			__FUNCTION__, sclk, baud_rate, tclkdiv, tfsdiv, rclkdiv);

 	return 0;
 }

 static irqreturn_t sport_uart_rx_irq(int irq, void *dev_id)
 {
 	struct sport_uart_port *up = dev_id;
 	struct tty_struct *tty = up->port.info->tty;
 	unsigned int ch;

 	do {
 		ch = rx_one_byte(up);
 		up->port.icount.rx++;

 		if (uart_handle_sysrq_char(&up->port, ch))
 			;
 		else
 			tty_insert_flip_char(tty, ch, TTY_NORMAL);
 	} while (SPORT_GET_STAT(up) & RXNE);
 	tty_flip_buffer_push(tty);

 	return IRQ_HANDLED;
 }

 static irqreturn_t sport_uart_tx_irq(int irq, void *dev_id)
 {
 	sport_uart_tx_chars(dev_id);

 	return IRQ_HANDLED;
 }

 static irqreturn_t sport_uart_err_irq(int irq, void *dev_id)
 {
 	struct sport_uart_port *up = dev_id;
 	struct tty_struct *tty = up->port.info->tty;
 	unsigned int stat = SPORT_GET_STAT(up);

 	/* Overflow in RX FIFO */
 	if (stat & ROVF) {
 		up->port.icount.overrun++;
 		tty_insert_flip_char(tty, 0, TTY_OVERRUN);
 		SPORT_PUT_STAT(up, ROVF); /* Clear ROVF bit */
 	}
 	/* These should not happen */
 	if (stat & (TOVF | TUVF | RUVF)) {
 		printk(KERN_ERR "SPORT Error:%s %s %s\n",
 				(stat & TOVF)?"TX overflow":"",
 				(stat & TUVF)?"TX underflow":"",
 				(stat & RUVF)?"RX underflow":"");
 		SPORT_PUT_TCR1(up, SPORT_GET_TCR1(up) & ~TSPEN);
 		SPORT_PUT_RCR1(up, SPORT_GET_RCR1(up) & ~RSPEN);
 	}
 	SSYNC();

 	return IRQ_HANDLED;
 }

 /* Reqeust IRQ, Setup clock */
 static int sport_startup(struct uart_port *port)
 {
 	struct sport_uart_port *up = (struct sport_uart_port *)port;
 	char buffer[20];
 	int retval;

 	pr_debug("%s enter\n", __FUNCTION__);
 	memset(buffer, 20, '\0');
 	snprintf(buffer, 20, "%s rx", up->name);
 	retval = request_irq(up->rx_irq, sport_uart_rx_irq, IRQF_SAMPLE_RANDOM, buffer, up);
 	if (retval) {
 		printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
 		return retval;
 	}

 	snprintf(buffer, 20, "%s tx", up->name);
 	retval = request_irq(up->tx_irq, sport_uart_tx_irq, IRQF_SAMPLE_RANDOM, buffer, up);
 	if (retval) {
 		printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
 		goto fail1;
 	}

 	snprintf(buffer, 20, "%s err", up->name);
 	retval = request_irq(up->err_irq, sport_uart_err_irq, IRQF_SAMPLE_RANDOM, buffer, up);
 	if (retval) {
 		printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
 		goto fail2;
 	}

 	if (port->line) {
 		if (peripheral_request_list(bfin_uart_pin_req_sport1, DRV_NAME))
 			goto fail3;
 	} else {
 		if (peripheral_request_list(bfin_uart_pin_req_sport0, DRV_NAME))
 			goto fail3;
 	}

 	sport_uart_setup(up, get_sclk(), port->uartclk);

 	/* Enable receive interrupt */
 	SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) | RSPEN));
 	SSYNC();

 	return 0;


 fail3:
 	printk(KERN_ERR DRV_NAME
 		": Requesting Peripherals failed\n");

 	free_irq(up->err_irq, up);
 fail2:
 	free_irq(up->tx_irq, up);
 fail1:
 	free_irq(up->rx_irq, up);

 	return retval;

 }

 static void sport_uart_tx_chars(struct sport_uart_port *up)
 {
 	struct circ_buf *xmit = &up->port.info->xmit;

 	if (SPORT_GET_STAT(up) & TXF)
 		return;

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

 	if (uart_circ_empty(xmit) || uart_tx_stopped(&up->port)) {
 		sport_stop_tx(&up->port);
 		return;
 	}

 	while(!(SPORT_GET_STAT(up) & TXF) && !uart_circ_empty(xmit)) {
 		tx_one_byte(up, xmit->buf[xmit->tail]);
 		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE -1);
 		up->port.icount.tx++;
 	}

 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(&up->port);
 }

 static unsigned int sport_tx_empty(struct uart_port *port)
 {
 	struct sport_uart_port *up = (struct sport_uart_port *)port;
 	unsigned int stat;

 	stat = SPORT_GET_STAT(up);
 	pr_debug("%s stat:%04x\n", __FUNCTION__, stat);
 	if (stat & TXHRE) {
 		return TIOCSER_TEMT;
 	} else
 		return 0;
 }

 static unsigned int sport_get_mctrl(struct uart_port *port)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 	return (TIOCM_CTS | TIOCM_CD | TIOCM_DSR);
 }

 static void sport_set_mctrl(struct uart_port *port, unsigned int mctrl)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 }

 static void sport_stop_tx(struct uart_port *port)
 {
 	struct sport_uart_port *up = (struct sport_uart_port *)port;
 	unsigned int stat;

 	pr_debug("%s enter\n", __FUNCTION__);

 	stat = SPORT_GET_STAT(up);
 	while(!(stat & TXHRE)) {
 		udelay(1);
 		stat = SPORT_GET_STAT(up);
 	}
 	/* Although the hold register is empty, last byte is still in shift
 	 * register and not sent out yet. If baud rate is lower than default,
 	 * delay should be longer. For example, if the baud rate is 9600,
 	 * the delay must be at least 2ms by experience */
 	udelay(500);

 	SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) & ~TSPEN));
 	SSYNC();

 	return;
 }

 static void sport_start_tx(struct uart_port *port)
 {
 	struct sport_uart_port *up = (struct sport_uart_port *)port;

 	pr_debug("%s enter\n", __FUNCTION__);
 	/* Write data into SPORT FIFO before enable SPROT to transmit */
 	sport_uart_tx_chars(up);

 	/* Enable transmit, then an interrupt will generated */
 	SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) | TSPEN));
 	SSYNC();
 	pr_debug("%s exit\n", __FUNCTION__);
 }

 static void sport_stop_rx(struct uart_port *port)
 {
 	struct sport_uart_port *up = (struct sport_uart_port *)port;

 	pr_debug("%s enter\n", __FUNCTION__);
 	/* Disable sport to stop rx */
 	SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) & ~RSPEN));
 	SSYNC();
 }

 static void sport_enable_ms(struct uart_port *port)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 }

 static void sport_break_ctl(struct uart_port *port, int break_state)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 }

 static void sport_shutdown(struct uart_port *port)
 {
 	struct sport_uart_port *up = (struct sport_uart_port *)port;

 	pr_debug("%s enter\n", __FUNCTION__);

 	/* Disable sport */
 	SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) & ~TSPEN));
 	SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) & ~RSPEN));
 	SSYNC();

 	if (port->line) {
 		peripheral_free_list(bfin_uart_pin_req_sport1);
 	} else {
 		peripheral_free_list(bfin_uart_pin_req_sport0);
 	}

 	free_irq(up->rx_irq, up);
 	free_irq(up->tx_irq, up);
 	free_irq(up->err_irq, up);
 }

 static void sport_set_termios(struct uart_port *port,
 		struct termios *termios, struct termios *old)
 {
 	pr_debug("%s enter, c_cflag:%08x\n", __FUNCTION__, termios->c_cflag);
 	uart_update_timeout(port, CS8 ,port->uartclk);
 }

 static const char *sport_type(struct uart_port *port)
 {
 	struct sport_uart_port *up = (struct sport_uart_port *)port;

 	pr_debug("%s enter\n", __FUNCTION__);
 	return up->name;
 }

 static void sport_release_port(struct uart_port *port)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 }

 static int sport_request_port(struct uart_port *port)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 	return 0;
 }

 static void sport_config_port(struct uart_port *port, int flags)
 {
 	struct sport_uart_port *up = (struct sport_uart_port *)port;

 	pr_debug("%s enter\n", __FUNCTION__);
 	up->port.type = PORT_BFIN_SPORT;
 }

 static int sport_verify_port(struct uart_port *port, struct serial_struct *ser)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 	return 0;
 }

 struct uart_ops sport_uart_ops = {
 	.tx_empty	= sport_tx_empty,
 	.set_mctrl	= sport_set_mctrl,
 	.get_mctrl	= sport_get_mctrl,
 	.stop_tx	= sport_stop_tx,
 	.start_tx	= sport_start_tx,
 	.stop_rx	= sport_stop_rx,
 	.enable_ms	= sport_enable_ms,
 	.break_ctl	= sport_break_ctl,
 	.startup	= sport_startup,
 	.shutdown	= sport_shutdown,
 	.set_termios	= sport_set_termios,
 	.type		= sport_type,
 	.release_port	= sport_release_port,
 	.request_port	= sport_request_port,
 	.config_port	= sport_config_port,
 	.verify_port	= sport_verify_port,
 };

 static struct sport_uart_port sport_uart_ports[] = {
 	{ /* SPORT 0 */
 		.name	= "SPORT0",
 		.tx_irq = IRQ_SPORT0_TX,
 		.rx_irq = IRQ_SPORT0_RX,
 		.err_irq= IRQ_SPORT0_ERROR,
 		.port	= {
 			.type		= PORT_BFIN_SPORT,
 			.iotype		= UPIO_MEM,
 			.membase	= (void __iomem *)SPORT0_TCR1,
 			.mapbase	= SPORT0_TCR1,
 			.irq		= IRQ_SPORT0_RX,
 			.uartclk	= CONFIG_SPORT_BAUD_RATE,
 			.fifosize	= 8,
 			.ops		= &sport_uart_ops,
 			.line		= 0,
 		},
 	}, { /* SPORT 1 */
 		.name	= "SPORT1",
 		.tx_irq = IRQ_SPORT1_TX,
 		.rx_irq = IRQ_SPORT1_RX,
 		.err_irq= IRQ_SPORT1_ERROR,
 		.port	= {
 			.type		= PORT_BFIN_SPORT,
 			.iotype		= UPIO_MEM,
 			.membase	= (void __iomem *)SPORT1_TCR1,
 			.mapbase	= SPORT1_TCR1,
 			.irq		= IRQ_SPORT1_RX,
 			.uartclk	= CONFIG_SPORT_BAUD_RATE,
 			.fifosize	= 8,
 			.ops		= &sport_uart_ops,
 			.line		= 1,
 		},
 	}
 };

 static struct uart_driver sport_uart_reg = {
 	.owner		= THIS_MODULE,
 	.driver_name	= "SPORT-UART",
 	.dev_name	= "ttySS",
 	.major		= 204,
 	.minor		= 84,
 	.nr		= ARRAY_SIZE(sport_uart_ports),
 	.cons		= NULL,
 };

 static int sport_uart_suspend(struct platform_device *dev, pm_message_t state)
 {
 	struct sport_uart_port *sport = platform_get_drvdata(dev);

 	pr_debug("%s enter\n", __FUNCTION__);
 	if (sport)
 		uart_suspend_port(&sport_uart_reg, &sport->port);

 	return 0;
 }

 static int sport_uart_resume(struct platform_device *dev)
 {
 	struct sport_uart_port *sport = platform_get_drvdata(dev);

 	pr_debug("%s enter\n", __FUNCTION__);
 	if (sport)
 		uart_resume_port(&sport_uart_reg, &sport->port);

 	return 0;
 }

 static int sport_uart_probe(struct platform_device *dev)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 	sport_uart_ports[dev->id].port.dev = &dev->dev;
 	uart_add_one_port(&sport_uart_reg, &sport_uart_ports[dev->id].port);
 	platform_set_drvdata(dev, &sport_uart_ports[dev->id]);

 	return 0;
 }

 static int sport_uart_remove(struct platform_device *dev)
 {
 	struct sport_uart_port *sport = platform_get_drvdata(dev);

 	pr_debug("%s enter\n", __FUNCTION__);
 	platform_set_drvdata(dev, NULL);

 	if (sport)
 		uart_remove_one_port(&sport_uart_reg, &sport->port);

 	return 0;
 }

 static struct platform_driver sport_uart_driver = {
 	.probe		= sport_uart_probe,
 	.remove		= sport_uart_remove,
 	.suspend	= sport_uart_suspend,
 	.resume		= sport_uart_resume,
 	.driver		= {
 		.name	= DRV_NAME,
 	},
 };

 static int __init sport_uart_init(void)
 {
 	int ret;

 	pr_debug("%s enter\n", __FUNCTION__);
 	ret = uart_register_driver(&sport_uart_reg);
 	if (ret != 0) {
 		printk(KERN_ERR "Failed to register %s:%d\n",
 				sport_uart_reg.driver_name, ret);
 		return ret;
 	}

 	ret = platform_driver_register(&sport_uart_driver);
 	if (ret != 0) {
 		printk(KERN_ERR "Failed to register sport uart driver:%d\n", ret);
 		uart_unregister_driver(&sport_uart_reg);
 	}


 	pr_debug("%s exit\n", __FUNCTION__);
 	return ret;
 }

 static void __exit sport_uart_exit(void)
 {
 	pr_debug("%s enter\n", __FUNCTION__);
 	platform_driver_unregister(&sport_uart_driver);
 	uart_unregister_driver(&sport_uart_reg);
 }

 module_init(sport_uart_init);
 module_exit(sport_uart_exit);

 MODULE_LICENSE("GPL");
	/*
	* File: linux/drivers/serial/bfin_sport_uart.c
	*
	* Based on: drivers/serial/bfin_5xx.c by Aubrey Li.
	* Author: Roy Huang <roy.huang@analog.com>
	*
	* Created: Nov 22, 2006
	* Copyright: (c) 2006-2007 Analog Devices Inc.
	* Description: this driver enable SPORTs on Blackfin emulate UART.
	*
	* This program is free software; you can redistribute it and/or modify
	* it under the terms of the GNU General Public License as published by
	* the Free Software Foundation; either version 2 of the License, or
	* (at your option) any later version.
	*
	* This program is distributed in the hope that 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 the file COPYING, or write
	* to the Free Software Foundation, Inc.,
	* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	*/

	/*
	* This driver and the hardware supported are in term of EE-191 of ADI.
	* http://www.analog.com/UploadedFiles/Application_Notes/399447663EE191.pdf
	* This application note describe how to implement a UART on a Sharc DSP,
	* but this driver is implemented on Blackfin Processor.
	*/

	/* After reset, there is a prelude of low level pulse when transmit data first
	* time. No addtional pulse in following transmit.
	* According to document:
	* The SPORTs are ready to start transmitting or receiving data no later than
	* three serial clock cycles after they are enabled in the SPORTx_TCR1 or
	* SPORTx_RCR1 register. No serial clock cycles are lost from this point on.
	* The first internal frame sync will occur one frame sync delay after the
	* SPORTs are ready. External frame syncs can occur as soon as the SPORT is
	* ready.
	*/

	/* Thanks to Axel Alatalo <axel@rubico.se> for fixing sport rx bug. Sometimes
	* sport receives data incorrectly. The following is Axel's words.
	* As EE-191, sport rx samples 3 times of the UART baudrate and takes the
	* middle smaple of every 3 samples as the data bit. For a 8-N-1 UART setting,
	* 30 samples will be required for a byte. If transmitter sends a 1/3 bit short
	* byte due to buadrate drift, then the 30th sample of a byte, this sample is
	* also the third sample of the stop bit, will happens on the immediately
	* following start bit which will be thrown away and missed. Thus since parts
	* of the startbit will be missed and the receiver will begin to drift, the
	* effect accumulates over time until synchronization is lost.
	* If only require 2 samples of the stopbit (by sampling in total 29 samples),
	* then a to short byte as in the case above will be tolerated. Then the 1/3
	* early startbit will trigger a framesync since the last read is complete
	* after only 2/3 stopbit and framesync is active during the last 1/3 looking
	* for a possible early startbit. */

	//#define DEBUG

	#include <linux/module.h>
	#include <linux/ioport.h>
	#include <linux/init.h>
	#include <linux/console.h>
	#include <linux/sysrq.h>
	#include <linux/platform_device.h>
	#include <linux/tty.h>
	#include <linux/tty_flip.h>
	#include <linux/serial_core.h>

	#include <asm/delay.h>
	#include <asm/portmux.h>

	#include "bfin_sport_uart.h"

	unsigned short bfin_uart_pin_req_sport0[] =
	{P_SPORT0_TFS, P_SPORT0_DTPRI, P_SPORT0_TSCLK, P_SPORT0_RFS, \
	P_SPORT0_DRPRI, P_SPORT0_RSCLK, P_SPORT0_DRSEC, P_SPORT0_DTSEC, 0};

	unsigned short bfin_uart_pin_req_sport1[] =
	{P_SPORT1_TFS, P_SPORT1_DTPRI, P_SPORT1_TSCLK, P_SPORT1_RFS, \
	P_SPORT1_DRPRI, P_SPORT1_RSCLK, P_SPORT1_DRSEC, P_SPORT1_DTSEC, 0};

	#define DRV_NAME "bfin-sport-uart"

	struct sport_uart_port {
	struct uart_port port;
	char *name;

	int tx_irq;
	int rx_irq;
	int err_irq;
	};

	static void sport_uart_tx_chars(struct sport_uart_port *up);
	static void sport_stop_tx(struct uart_port *port);

	static inline void tx_one_byte(struct sport_uart_port *up, unsigned int value)
	{
	pr_debug("%s value:%x\n", __FUNCTION__, value);
	/* Place a Start and Stop bit */
	__asm__ volatile (
	"R2 = b#01111111100;\n\t"
	"R3 = b#10000000001;\n\t"
	"%0 <<= 2;\n\t"
	"%0 = %0 & R2;\n\t"
	"%0 = %0 \| R3;\n\t"
	:"=r"(value)
	:"0"(value)
	:"R2", "R3");
	pr_debug("%s value:%x\n", __FUNCTION__, value);

	SPORT_PUT_TX(up, value);
	}

	static inline unsigned int rx_one_byte(struct sport_uart_port *up)
	{
	unsigned int value, extract;

	value = SPORT_GET_RX32(up);
	pr_debug("%s value:%x\n", __FUNCTION__, value);

	/* Extract 8 bits data */
	__asm__ volatile (
	"R5 = 0;\n\t"
	"P0 = 8;\n\t"
	"R1 = 0x1801(Z);\n\t"
	"R3 = 0x0300(Z);\n\t"
	"R4 = 0;\n\t"
	"LSETUP(loop_s, loop_e) LC0 = P0;\nloop_s:\t"
	"R2 = extract(%1, R1.L)(Z);\n\t"
	"R2 <<= R4;\n\t"
	"R5 = R5 \| R2;\n\t"
	"R1 = R1 - R3;\nloop_e:\t"
	"R4 += 1;\n\t"
	"%0 = R5;\n\t"
	:"=r"(extract)
	:"r"(value)
	:"P0", "R1", "R2","R3","R4", "R5");

	pr_debug(" extract:%x\n", extract);
	return extract;
	}

	static int sport_uart_setup(struct sport_uart_port *up, int sclk, int baud_rate)
	{
	int tclkdiv, tfsdiv, rclkdiv;

	/* Set TCR1 and TCR2 */
	SPORT_PUT_TCR1(up, (LTFS \| ITFS \| TFSR \| TLSBIT \| ITCLK));
	SPORT_PUT_TCR2(up, 10);
	pr_debug("%s TCR1:%x, TCR2:%x\n", __FUNCTION__, SPORT_GET_TCR1(up), SPORT_GET_TCR2(up));

	/* Set RCR1 and RCR2 */
	SPORT_PUT_RCR1(up, (RCKFE \| LARFS \| LRFS \| RFSR \| IRCLK));
	SPORT_PUT_RCR2(up, 28);
	pr_debug("%s RCR1:%x, RCR2:%x\n", __FUNCTION__, SPORT_GET_RCR1(up), SPORT_GET_RCR2(up));

	tclkdiv = sclk/(2 * baud_rate) - 1;
	tfsdiv = 12;
	rclkdiv = sclk/(2 * baud_rate * 3) - 1;
	SPORT_PUT_TCLKDIV(up, tclkdiv);
	SPORT_PUT_TFSDIV(up, tfsdiv);
	SPORT_PUT_RCLKDIV(up, rclkdiv);
	SSYNC();
	pr_debug("%s sclk:%d, baud_rate:%d, tclkdiv:%d, tfsdiv:%d, rclkdiv:%d\n",
	__FUNCTION__, sclk, baud_rate, tclkdiv, tfsdiv, rclkdiv);

	return 0;
	}

	static irqreturn_t sport_uart_rx_irq(int irq, void *dev_id)
	{
	struct sport_uart_port *up = dev_id;
	struct tty_struct *tty = up->port.info->tty;
	unsigned int ch;

	do {
	ch = rx_one_byte(up);
	up->port.icount.rx++;

	if (uart_handle_sysrq_char(&up->port, ch))
	;
	else
	tty_insert_flip_char(tty, ch, TTY_NORMAL);
	} while (SPORT_GET_STAT(up) & RXNE);
	tty_flip_buffer_push(tty);

	return IRQ_HANDLED;
	}

	static irqreturn_t sport_uart_tx_irq(int irq, void *dev_id)
	{
	sport_uart_tx_chars(dev_id);

	return IRQ_HANDLED;
	}

	static irqreturn_t sport_uart_err_irq(int irq, void *dev_id)
	{
	struct sport_uart_port *up = dev_id;
	struct tty_struct *tty = up->port.info->tty;
	unsigned int stat = SPORT_GET_STAT(up);

	/* Overflow in RX FIFO */
	if (stat & ROVF) {
	up->port.icount.overrun++;
	tty_insert_flip_char(tty, 0, TTY_OVERRUN);
	SPORT_PUT_STAT(up, ROVF); /* Clear ROVF bit */
	}
	/* These should not happen */
	if (stat & (TOVF \| TUVF \| RUVF)) {
	printk(KERN_ERR "SPORT Error:%s %s %s\n",
	(stat & TOVF)?"TX overflow":"",
	(stat & TUVF)?"TX underflow":"",
	(stat & RUVF)?"RX underflow":"");
	SPORT_PUT_TCR1(up, SPORT_GET_TCR1(up) & ~TSPEN);
	SPORT_PUT_RCR1(up, SPORT_GET_RCR1(up) & ~RSPEN);
	}
	SSYNC();

	return IRQ_HANDLED;
	}

	/* Reqeust IRQ, Setup clock */
	static int sport_startup(struct uart_port *port)
	{
	struct sport_uart_port up = (struct sport_uart_port )port;
	char buffer[20];
	int retval;

	pr_debug("%s enter\n", __FUNCTION__);
	memset(buffer, 20, '\0');
	snprintf(buffer, 20, "%s rx", up->name);
	retval = request_irq(up->rx_irq, sport_uart_rx_irq, IRQF_SAMPLE_RANDOM, buffer, up);
	if (retval) {
	printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
	return retval;
	}

	snprintf(buffer, 20, "%s tx", up->name);
	retval = request_irq(up->tx_irq, sport_uart_tx_irq, IRQF_SAMPLE_RANDOM, buffer, up);
	if (retval) {
	printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
	goto fail1;
	}

	snprintf(buffer, 20, "%s err", up->name);
	retval = request_irq(up->err_irq, sport_uart_err_irq, IRQF_SAMPLE_RANDOM, buffer, up);
	if (retval) {
	printk(KERN_ERR "Unable to request interrupt %s\n", buffer);
	goto fail2;
	}

	if (port->line) {
	if (peripheral_request_list(bfin_uart_pin_req_sport1, DRV_NAME))
	goto fail3;
	} else {
	if (peripheral_request_list(bfin_uart_pin_req_sport0, DRV_NAME))
	goto fail3;
	}

	sport_uart_setup(up, get_sclk(), port->uartclk);

	/* Enable receive interrupt */
	SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) \| RSPEN));
	SSYNC();

	return 0;


	fail3:
	printk(KERN_ERR DRV_NAME
	": Requesting Peripherals failed\n");

	free_irq(up->err_irq, up);
	fail2:
	free_irq(up->tx_irq, up);
	fail1:
	free_irq(up->rx_irq, up);

	return retval;

	}

	static void sport_uart_tx_chars(struct sport_uart_port *up)
	{
	struct circ_buf *xmit = &up->port.info->xmit;

	if (SPORT_GET_STAT(up) & TXF)
	return;

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

	if (uart_circ_empty(xmit) \|\| uart_tx_stopped(&up->port)) {
	sport_stop_tx(&up->port);
	return;
	}

	while(!(SPORT_GET_STAT(up) & TXF) && !uart_circ_empty(xmit)) {
	tx_one_byte(up, xmit->buf[xmit->tail]);
	xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE -1);
	up->port.icount.tx++;
	}

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
	uart_write_wakeup(&up->port);
	}

	static unsigned int sport_tx_empty(struct uart_port *port)
	{
	struct sport_uart_port up = (struct sport_uart_port )port;
	unsigned int stat;

	stat = SPORT_GET_STAT(up);
	pr_debug("%s stat:%04x\n", __FUNCTION__, stat);
	if (stat & TXHRE) {
	return TIOCSER_TEMT;
	} else
	return 0;
	}

	static unsigned int sport_get_mctrl(struct uart_port *port)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	return (TIOCM_CTS \| TIOCM_CD \| TIOCM_DSR);
	}

	static void sport_set_mctrl(struct uart_port *port, unsigned int mctrl)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	}

	static void sport_stop_tx(struct uart_port *port)
	{
	struct sport_uart_port up = (struct sport_uart_port )port;
	unsigned int stat;

	pr_debug("%s enter\n", __FUNCTION__);

	stat = SPORT_GET_STAT(up);
	while(!(stat & TXHRE)) {
	udelay(1);
	stat = SPORT_GET_STAT(up);
	}
	/* Although the hold register is empty, last byte is still in shift
	* register and not sent out yet. If baud rate is lower than default,
	* delay should be longer. For example, if the baud rate is 9600,
	* the delay must be at least 2ms by experience */
	udelay(500);

	SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) & ~TSPEN));
	SSYNC();

	return;
	}

	static void sport_start_tx(struct uart_port *port)
	{
	struct sport_uart_port up = (struct sport_uart_port )port;

	pr_debug("%s enter\n", __FUNCTION__);
	/* Write data into SPORT FIFO before enable SPROT to transmit */
	sport_uart_tx_chars(up);

	/* Enable transmit, then an interrupt will generated */
	SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) \| TSPEN));
	SSYNC();
	pr_debug("%s exit\n", __FUNCTION__);
	}

	static void sport_stop_rx(struct uart_port *port)
	{
	struct sport_uart_port up = (struct sport_uart_port )port;

	pr_debug("%s enter\n", __FUNCTION__);
	/* Disable sport to stop rx */
	SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) & ~RSPEN));
	SSYNC();
	}

	static void sport_enable_ms(struct uart_port *port)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	}

	static void sport_break_ctl(struct uart_port *port, int break_state)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	}

	static void sport_shutdown(struct uart_port *port)
	{
	struct sport_uart_port up = (struct sport_uart_port )port;

	pr_debug("%s enter\n", __FUNCTION__);

	/* Disable sport */
	SPORT_PUT_TCR1(up, (SPORT_GET_TCR1(up) & ~TSPEN));
	SPORT_PUT_RCR1(up, (SPORT_GET_RCR1(up) & ~RSPEN));
	SSYNC();

	if (port->line) {
	peripheral_free_list(bfin_uart_pin_req_sport1);
	} else {
	peripheral_free_list(bfin_uart_pin_req_sport0);
	}

	free_irq(up->rx_irq, up);
	free_irq(up->tx_irq, up);
	free_irq(up->err_irq, up);
	}

	static void sport_set_termios(struct uart_port *port,
	struct termios termios, struct termios old)
	{
	pr_debug("%s enter, c_cflag:%08x\n", __FUNCTION__, termios->c_cflag);
	uart_update_timeout(port, CS8 ,port->uartclk);
	}

	static const char sport_type(struct uart_port port)
	{
	struct sport_uart_port up = (struct sport_uart_port )port;

	pr_debug("%s enter\n", __FUNCTION__);
	return up->name;
	}

	static void sport_release_port(struct uart_port *port)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	}

	static int sport_request_port(struct uart_port *port)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	return 0;
	}

	static void sport_config_port(struct uart_port *port, int flags)
	{
	struct sport_uart_port up = (struct sport_uart_port )port;

	pr_debug("%s enter\n", __FUNCTION__);
	up->port.type = PORT_BFIN_SPORT;
	}

	static int sport_verify_port(struct uart_port port, struct serial_struct ser)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	return 0;
	}

	struct uart_ops sport_uart_ops = {
	.tx_empty = sport_tx_empty,
	.set_mctrl = sport_set_mctrl,
	.get_mctrl = sport_get_mctrl,
	.stop_tx = sport_stop_tx,
	.start_tx = sport_start_tx,
	.stop_rx = sport_stop_rx,
	.enable_ms = sport_enable_ms,
	.break_ctl = sport_break_ctl,
	.startup = sport_startup,
	.shutdown = sport_shutdown,
	.set_termios = sport_set_termios,
	.type = sport_type,
	.release_port = sport_release_port,
	.request_port = sport_request_port,
	.config_port = sport_config_port,
	.verify_port = sport_verify_port,
	};

	static struct sport_uart_port sport_uart_ports[] = {
	{ /* SPORT 0 */
	.name = "SPORT0",
	.tx_irq = IRQ_SPORT0_TX,
	.rx_irq = IRQ_SPORT0_RX,
	.err_irq= IRQ_SPORT0_ERROR,
	.port = {
	.type = PORT_BFIN_SPORT,
	.iotype = UPIO_MEM,
	.membase = (void __iomem *)SPORT0_TCR1,
	.mapbase = SPORT0_TCR1,
	.irq = IRQ_SPORT0_RX,
	.uartclk = CONFIG_SPORT_BAUD_RATE,
	.fifosize = 8,
	.ops = &sport_uart_ops,
	.line = 0,
	},
	}, { /* SPORT 1 */
	.name = "SPORT1",
	.tx_irq = IRQ_SPORT1_TX,
	.rx_irq = IRQ_SPORT1_RX,
	.err_irq= IRQ_SPORT1_ERROR,
	.port = {
	.type = PORT_BFIN_SPORT,
	.iotype = UPIO_MEM,
	.membase = (void __iomem *)SPORT1_TCR1,
	.mapbase = SPORT1_TCR1,
	.irq = IRQ_SPORT1_RX,
	.uartclk = CONFIG_SPORT_BAUD_RATE,
	.fifosize = 8,
	.ops = &sport_uart_ops,
	.line = 1,
	},
	}
	};

	static struct uart_driver sport_uart_reg = {
	.owner = THIS_MODULE,
	.driver_name = "SPORT-UART",
	.dev_name = "ttySS",
	.major = 204,
	.minor = 84,
	.nr = ARRAY_SIZE(sport_uart_ports),
	.cons = NULL,
	};

	static int sport_uart_suspend(struct platform_device *dev, pm_message_t state)
	{
	struct sport_uart_port *sport = platform_get_drvdata(dev);

	pr_debug("%s enter\n", __FUNCTION__);
	if (sport)
	uart_suspend_port(&sport_uart_reg, &sport->port);

	return 0;
	}

	static int sport_uart_resume(struct platform_device *dev)
	{
	struct sport_uart_port *sport = platform_get_drvdata(dev);

	pr_debug("%s enter\n", __FUNCTION__);
	if (sport)
	uart_resume_port(&sport_uart_reg, &sport->port);

	return 0;
	}

	static int sport_uart_probe(struct platform_device *dev)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	sport_uart_ports[dev->id].port.dev = &dev->dev;
	uart_add_one_port(&sport_uart_reg, &sport_uart_ports[dev->id].port);
	platform_set_drvdata(dev, &sport_uart_ports[dev->id]);

	return 0;
	}

	static int sport_uart_remove(struct platform_device *dev)
	{
	struct sport_uart_port *sport = platform_get_drvdata(dev);

	pr_debug("%s enter\n", __FUNCTION__);
	platform_set_drvdata(dev, NULL);

	if (sport)
	uart_remove_one_port(&sport_uart_reg, &sport->port);

	return 0;
	}

	static struct platform_driver sport_uart_driver = {
	.probe = sport_uart_probe,
	.remove = sport_uart_remove,
	.suspend = sport_uart_suspend,
	.resume = sport_uart_resume,
	.driver = {
	.name = DRV_NAME,
	},
	};

	static int __init sport_uart_init(void)
	{
	int ret;

	pr_debug("%s enter\n", __FUNCTION__);
	ret = uart_register_driver(&sport_uart_reg);
	if (ret != 0) {
	printk(KERN_ERR "Failed to register %s:%d\n",
	sport_uart_reg.driver_name, ret);
	return ret;
	}

	ret = platform_driver_register(&sport_uart_driver);
	if (ret != 0) {
	printk(KERN_ERR "Failed to register sport uart driver:%d\n", ret);
	uart_unregister_driver(&sport_uart_reg);
	}


	pr_debug("%s exit\n", __FUNCTION__);
	return ret;
	}

	static void __exit sport_uart_exit(void)
	{
	pr_debug("%s enter\n", __FUNCTION__);
	platform_driver_unregister(&sport_uart_driver);
	uart_unregister_driver(&sport_uart_reg);
	}

	module_init(sport_uart_init);
	module_exit(sport_uart_exit);

	MODULE_LICENSE("GPL");