at91_serial.c

fft的工业级的EP9315的开发板的所有驱动程序

/*
 *  linux/drivers/char/at91_serial.c
 *
 *  Driver for Atmel AT91RM9200 Serial ports
 *
 *  Copyright (c) Rick Bronson
 *
 *  Based on drivers/char/serial_sa1100.c, by Deep Blue Solutions Ltd.
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>

#include <asm/arch/AT91RM9200_USART.h>
#include <asm/arch/pio.h>

/*
 * This is a temporary structure for registering these
 * functions; it is intended to be discarded after boot.
 */
struct uart_port;
struct uart_info;
struct at91_port_fns {
	void	(*set_mctrl)(struct uart_port *, u_int);
	u_int	(*get_mctrl)(struct uart_port *);
	void	(*enable_ms)(struct uart_port *);
	void	(*pm)(struct uart_port *, u_int, u_int);
	int	(*set_wake)(struct uart_port *, u_int);
	int	(*open)(struct uart_port *, struct uart_info *);
	void	(*close)(struct uart_port *, struct uart_info *);
};

#if defined(CONFIG_SERIAL_AT91_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>

#define SERIAL_AT91_MAJOR	TTY_MAJOR
#define CALLOUT_AT91_MAJOR	TTYAUX_MAJOR
#define MINOR_START		64

#define AT91C_VA_BASE_DBGU	((unsigned long) &(AT91_SYS->DBGU_CR))
#define AT91_ISR_PASS_LIMIT	256

#define UART_PUT_CR(port,v)	((AT91PS_USART)(port)->membase)->US_CR = v
#define UART_GET_MR(port)	((AT91PS_USART)(port)->membase)->US_MR
#define UART_PUT_MR(port,v)	((AT91PS_USART)(port)->membase)->US_MR = v
#define UART_PUT_IER(port,v)	((AT91PS_USART)(port)->membase)->US_IER = v
#define UART_PUT_IDR(port,v)	((AT91PS_USART)(port)->membase)->US_IDR = v
#define UART_GET_IMR(port)	((AT91PS_USART)(port)->membase)->US_IMR
#define UART_GET_CSR(port)	((AT91PS_USART)(port)->membase)->US_CSR
#define UART_GET_CHAR(port)	((AT91PS_USART)(port)->membase)->US_RHR
#define UART_PUT_CHAR(port,v)	((AT91PS_USART)(port)->membase)->US_THR = v
#define UART_GET_BRGR(port)	((AT91PS_USART)(port)->membase)->US_BRGR
#define UART_PUT_BRGR(port,v)	((AT91PS_USART)(port)->membase)->US_BRGR = v

// #define UART_GET_CR(port)	((AT91PS_USART)(port)->membase)->US_CR		// is write-only

static struct tty_driver normal, callout;
static struct tty_struct *at91_table[AT91C_NR_UART];
static struct termios *at91_termios[AT91C_NR_UART], *at91_termios_locked[AT91C_NR_UART];
static int (*at91_open)(struct uart_port *, struct uart_info *);
static void (*at91_close)(struct uart_port *, struct uart_info *);

#ifdef SUPPORT_SYSRQ
static struct console at91_console;
#endif

/*
 * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
 */
static u_int at91_tx_empty(struct uart_port *port)
{
	return UART_GET_CSR(port) & AT91C_US_TXEMPTY ? TIOCSER_TEMT : 0;
}

/*
 * Set state of the modem control output lines
 */
static void at91_set_mctrl(struct uart_port *port, u_int mctrl)
{
	unsigned int control = 0;

	if (mctrl & TIOCM_RTS)
		control |= AT91C_US_RTSEN;
	else
		control |= AT91C_US_RTSDIS;

	if (mctrl & TIOCM_DTR)
		control |= AT91C_US_DTREN;
	else
		control |=  AT91C_US_DTRDIS;

	UART_PUT_CR(port,control);
}

/*
 * Get state of the modem control input lines
 */
static u_int at91_get_mctrl(struct uart_port *port)
{
	unsigned int status, ret = 0;

	status = UART_GET_CSR(port);
	if (status & AT91C_US_DCD)
		ret |= TIOCM_CD;
	if (status & AT91C_US_CTS)
		ret |= TIOCM_CTS;
	if (status & AT91C_US_DSR)
		ret |= TIOCM_DSR;
	if (status & AT91C_US_RI)
		ret |= TIOCM_RI;

	return ret;
}

/*
 * Stop transmitting.
 */
static void at91_stop_tx(struct uart_port *port, u_int from_tty)
{
	UART_PUT_IDR(port, AT91C_US_TXRDY);
	port->read_status_mask &= ~AT91C_US_TXRDY;
}

/*
 * Start transmitting.
 */
static void at91_start_tx(struct uart_port *port, u_int nonempty, u_int from_tty)
{
	if (nonempty) {
		unsigned long flags;

		local_irq_save(flags);
		port->read_status_mask |= AT91C_US_TXRDY;
		UART_PUT_IER(port, AT91C_US_TXRDY);
		local_irq_restore(flags);
	}
}

/*
 * Stop receiving - port is in process of being closed.
 */
static void at91_stop_rx(struct uart_port *port)
{
	UART_PUT_IDR(port, AT91C_US_RXRDY);
}

/*
 * Enable modem status interrupts
 */
static void at91_enable_ms(struct uart_port *port)
{
	UART_PUT_IER(port, AT91C_US_RIIC | AT91C_US_DSRIC | AT91C_US_DCDIC | AT91C_US_CTSIC);
}

/*
 * Control the transmission of a break signal
 */
static void at91_break_ctl(struct uart_port *port, int break_state)
{
	if (break_state != 0)
		UART_PUT_CR(port, AT91C_US_STTBRK);	/* start break */
	else
		UART_PUT_CR(port, AT91C_US_STPBRK);	/* stop break */
}

/*
 * Characters received (called from interrupt handler)
 */
static void at91_rx_chars(struct uart_info *info, struct pt_regs *regs)
{
	struct tty_struct *tty = info->tty;
	struct uart_port *port = info->port;
	unsigned int status, ch, flg, ignored = 0;

	status = UART_GET_CSR(port);
	while (status & (AT91C_US_RXRDY)) {
		ch = UART_GET_CHAR(port);

		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
			goto ignore_char;
		port->icount.rx++;

		flg = TTY_NORMAL;

		/*
		 * note that the error handling code is
		 * out of the main execution path
		 */
		if (status & (AT91C_US_PARE | AT91C_US_FRAME | AT91C_US_OVRE))
			goto handle_error;

		if (uart_handle_sysrq_char(info, ch, regs))
			goto ignore_char;

	error_return:
		*tty->flip.flag_buf_ptr++ = flg;
		*tty->flip.char_buf_ptr++ = ch;
		tty->flip.count++;
	ignore_char:
		status = UART_GET_CSR(port);
	}
out:
	tty_flip_buffer_push(tty);
	return;

handle_error:
	if (status & (AT91C_US_PARE | AT91C_US_FRAME | AT91C_US_OVRE))
		UART_PUT_CR(port, AT91C_US_RSTSTA);  /* clear error */
	if (status & (AT91C_US_PARE))
		port->icount.parity++;
	else if (status & (AT91C_US_FRAME))
		port->icount.frame++;
	if (status & (AT91C_US_OVRE))
		port->icount.overrun++;

	if (status & port->ignore_status_mask) {
		if (++ignored > 100)
			goto out;
		goto ignore_char;
	}

	status &= port->read_status_mask;

	UART_PUT_CR(port, AT91C_US_RSTSTA);  /* clear error */
	if (status & AT91C_US_PARE)
		flg = TTY_PARITY;
	else if (status & AT91C_US_FRAME)
		flg = TTY_FRAME;

	if (status & AT91C_US_OVRE) {
		/*
		 * overrun does *not* affect the character
		 * we read from the FIFO
		 */
		*tty->flip.flag_buf_ptr++ = flg;
		*tty->flip.char_buf_ptr++ = ch;
		tty->flip.count++;
		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
			goto ignore_char;
		ch = 0;
		flg = TTY_OVERRUN;
	}
#ifdef SUPPORT_SYSRQ
	info->sysrq = 0;
#endif
	goto error_return;
}

/*
 * Transmit characters (called from interrupt handler)
 */
static void at91_tx_chars(struct uart_info *info)
{
	struct uart_port *port = info->port;

	if (port->x_char) {
		UART_PUT_CHAR(port, port->x_char);
		port->icount.tx++;
		port->x_char = 0;
		return;
	}
	if (info->xmit.head == info->xmit.tail
	    || info->tty->stopped
	    || info->tty->hw_stopped) {
		at91_stop_tx(info->port, 0);
		return;
	}

	while (UART_GET_CSR(port) & AT91C_US_TXRDY) {
		UART_PUT_CHAR(port, info->xmit.buf[info->xmit.tail]);
		info->xmit.tail = (info->xmit.tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;
		if (info->xmit.head == info->xmit.tail)
			break;
	}

	if (CIRC_CNT(info->xmit.head, info->xmit.tail, UART_XMIT_SIZE) < WAKEUP_CHARS)
		uart_event(info, EVT_WRITE_WAKEUP);

	if (info->xmit.head == info->xmit.tail)
		at91_stop_tx(info->port, 0);
}

/*
 * Interrupt handler
 */
static void at91_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct uart_info *info = dev_id;
	struct uart_port *port = info->port;
	unsigned int status, pending, pass_counter = 0;

	status = UART_GET_CSR(port);
	pending = status & port->read_status_mask;
	if (pending) {
		do {
			if (pending & AT91C_US_RXRDY)
				at91_rx_chars(info, regs);

			/* Clear the relevent break bits */
			if (pending & AT91C_US_RXBRK) {
				UART_PUT_CR(port, AT91C_US_RSTSTA);
				port->icount.brk++;
#ifdef SUPPORT_SYSRQ
				if (port->line == at91_console.index && !info->sysrq) {
					info->sysrq = jiffies + HZ*5;
				}
#endif
			}

			// TODO: All reads to CSR will clear these interrupts!
			if (pending & AT91C_US_RIIC) port->icount.rng++;
			if (pending & AT91C_US_DSRIC) port->icount.dsr++;
			if (pending & AT91C_US_DCDIC) {
				port->icount.dcd++;
				uart_handle_dcd_change(info, status & AT91C_US_DCD);
			}
			if (pending & AT91C_US_CTSIC) {
				port->icount.cts++;
				uart_handle_cts_change(info, status & AT91C_US_CTS);
			}
			if (pending & (AT91C_US_RIIC | AT91C_US_DSRIC | AT91C_US_DCDIC | AT91C_US_CTSIC))
				wake_up_interruptible(&info->delta_msr_wait);

			if (pending & AT91C_US_TXRDY)
				at91_tx_chars(info);
			if (pass_counter++ > AT91_ISR_PASS_LIMIT)
				break;

			status = UART_GET_CSR(port);
			pending = status & port->read_status_mask;
		} while (pending);
	}
}

/*
 * Perform initialization and enable port for reception
 */
static int at91_startup(struct uart_port *port, struct uart_info *info)
{
	int retval;

	/*
	 * Allocate the IRQ
	 */
	retval = request_irq(port->irq, at91_interrupt, SA_SHIRQ, "at91_serial", info);
	if (retval) {
		printk("at91_serial: at91_startup - Can't get irq\n");
		return retval;
	}
	/*
	 * If there is a specific "open" function (to register
	 * control line interrupts)
	 */
	if (at91_open) {
		retval = at91_open(port, info);
		if (retval) {
			free_irq(port->irq, info);
			return retval;
		}
	}

	/* Enable peripheral clock if required */
	if (port->irq != AT91C_ID_SYS)
		AT91_SYS->PMC_PCER = 1 << port->irq;

	port->read_status_mask = AT91C_US_RXRDY | AT91C_US_TXRDY | AT91C_US_OVRE
			| AT91C_US_FRAME | AT91C_US_PARE | AT91C_US_RXBRK;
	/*
	 * Finally, clear and enable interrupts
	 */
	UART_PUT_IDR(port, -1);
	UART_PUT_CR(port, AT91C_US_TXEN | AT91C_US_RXEN);  /* enable xmit & rcvr */
	UART_PUT_IER(port, AT91C_US_RXRDY);  /* do receive only */
	return 0;
}

/*
 * Disable the port
 */
static void at91_shutdown(struct uart_port *port, struct uart_info *info)
{
	/*
	 * Free the interrupt
	 */
	free_irq(port->irq, info);

	/*
	 * If there is a specific "close" function (to unregister
	 * control line interrupts)
	 */
	if (at91_close)
		at91_close(port, info);