s3c2410.c

Linux Kernel 2.6.9 for OMAP1710

/*
 * linux/drivers/char/s3c2410.c
 *
 * Driver for onboard UARTs on the Samsung S3C2410
 *
 * Based on drivers/char/serial.c and drivers/char/21285.c
 *
 * Ben Dooks, (c) 2003 Simtec Electronics
 *
 * Changelog:
 *
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/device.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/serial_core.h>
#include <linux/serial.h>

#include <asm/io.h>
#include <asm/irq.h>

#include <asm/hardware.h>
#include <asm/arch/regs-serial.h>

#if 0
#include <asm/debug-ll.h>
#define dbg(x...) llprintk(x)
#else
#define dbg(x...)
#endif

#define SERIAL_S3C2410_NAME	"ttySAC"
#define SERIAL_S3C2410_MAJOR	204
#define SERIAL_S3C2410_MINOR	64

/* we can support 3 uarts, but not always use them */

#define NR_PORTS (3)

static const char serial_s3c2410_name[] = "Samsung S3C2410 UART";

/* port irq numbers */

#define TX_IRQ(port) ((port)->irq + 1)
#define RX_IRQ(port) ((port)->irq)

#define tx_enabled(port) ((port)->unused[0])
#define rx_enabled(port) ((port)->unused[1])

/* flag to ignore all characters comming in */
#define RXSTAT_DUMMY_READ (0x10000000)

/* access functions */

#define portaddr(port, reg) ((void *)((port)->membase + (reg)))

#define rd_regb(port, reg) (__raw_readb(portaddr(port, reg)))
#define rd_regl(port, reg) (__raw_readl(portaddr(port, reg)))

#define wr_regb(port, reg, val) \
  do { __raw_writeb(val, portaddr(port, reg)); } while(0)

#define wr_regl(port, reg, val) \
  do { __raw_writel(val, portaddr(port, reg)); } while(0)




/* code */

static void
serial_s3c2410_stop_tx(struct uart_port *port, unsigned int tty_stop)
{
	if (tx_enabled(port)) {
		disable_irq(TX_IRQ(port));
		tx_enabled(port) = 0;
	}
}

static void
serial_s3c2410_start_tx(struct uart_port *port, unsigned int tty_start)
{
	if (!tx_enabled(port)) {
		enable_irq(TX_IRQ(port));
		tx_enabled(port) = 1;
	}
}

static void serial_s3c2410_stop_rx(struct uart_port *port)
{
	if (rx_enabled(port)) {
		dbg("serial_s3c2410_stop_rx: port=%p\n", port);
		disable_irq(RX_IRQ(port));
		rx_enabled(port) = 0;
	}
}

static void serial_s3c2410_enable_ms(struct uart_port *port)
{
}

/* ? - where has parity gone?? */
#define S3C2410_UERSTAT_PARITY (0x1000)

static irqreturn_t
serial_s3c2410_rx_chars(int irq, void *dev_id, struct pt_regs *regs)
{
	struct uart_port *port = dev_id;
	struct tty_struct *tty = port->info->tty;
	unsigned int ufcon, ch, rxs, ufstat;
	int max_count = 256;

	while (max_count-- > 0) {
		ufcon = rd_regl(port, S3C2410_UFCON);
		ufstat = rd_regl(port, S3C2410_UFSTAT);

		if (S3C2410_UFCON_RXC(ufstat) == 0)
			break;

		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
			tty->flip.work.func((void *)tty);
			if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
				printk(KERN_WARNING "TTY_DONT_FLIP set\n");
				goto out;
			}
		}

		ch = rd_regb(port, S3C2410_URXH);

		*tty->flip.char_buf_ptr = ch;
		*tty->flip.flag_buf_ptr = TTY_NORMAL;
		port->icount.rx++;

		rxs = rd_regb(port, S3C2410_UERSTAT) | RXSTAT_DUMMY_READ;

		if (rxs & S3C2410_UERSTAT_ANY) {
			if (rxs & S3C2410_UERSTAT_FRAME)
				port->icount.frame++;
			if (rxs & S3C2410_UERSTAT_OVERRUN)
				port->icount.overrun++;

			rxs &= port->read_status_mask;

			if (rxs & S3C2410_UERSTAT_PARITY)
				*tty->flip.flag_buf_ptr = TTY_PARITY;
			else if (rxs & ( S3C2410_UERSTAT_FRAME | S3C2410_UERSTAT_OVERRUN))
				*tty->flip.flag_buf_ptr = TTY_FRAME;
		}

		if ((rxs & port->ignore_status_mask) == 0) {
			tty->flip.flag_buf_ptr++;
			tty->flip.char_buf_ptr++;
			tty->flip.count++;
		}

		if ((rxs & S3C2410_UERSTAT_OVERRUN) &&
		    tty->flip.count < TTY_FLIPBUF_SIZE) {
			/*
			 * Overrun is special, since it's reported
			 * immediately, and doesn't affect the current
			 * character.
			 */
			*tty->flip.char_buf_ptr++ = 0;
			*tty->flip.flag_buf_ptr++ = TTY_OVERRUN;
			tty->flip.count++;
		}
	}
	tty_flip_buffer_push(tty);

 out:
	return IRQ_HANDLED;
}

static irqreturn_t
serial_s3c2410_tx_chars(int irq, void *dev_id, struct pt_regs *regs)
{
	struct uart_port *port = (struct uart_port *)dev_id;
	struct circ_buf *xmit = &port->info->xmit;
	int count = 256;

	if (port->x_char) {
		wr_regb(port, S3C2410_UTXH, port->x_char);
		port->icount.tx++;
		port->x_char = 0;
		goto out;
	}

	/* if there isnt anything more to transmit, or the uart is now
	 * stopped, disable the uart and exit
	*/

	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
		serial_s3c2410_stop_tx(port, 0);
		goto out;
	}

	/* try and drain the buffer... */

	while (!uart_circ_empty(xmit) && count-- > 0) {
		if (rd_regl(port, S3C2410_UFSTAT) & S3C2410_UFSTAT_TXFULL)
			break;

		wr_regb(port, S3C2410_UTXH, xmit->buf[xmit->tail]);
		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;
	}

	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
		uart_write_wakeup(port);

	if (uart_circ_empty(xmit))
		serial_s3c2410_stop_tx(port, 0);

 out:
	return IRQ_HANDLED;
}

static unsigned int
serial_s3c2410_tx_empty(struct uart_port *port)
{
	unsigned int ufcon = rd_regl(port, S3C2410_UFCON);
	return (S3C2410_UFCON_TXC(ufcon) != 0) ? 0 : TIOCSER_TEMT;
}

/* no modem control lines */
static unsigned int
serial_s3c2410_get_mctrl(struct uart_port *port)
{
	unsigned int umstat = rd_regb(port,S3C2410_UMSTAT);

	if (umstat & S3C2410_UMSTAT_CTS)
		return TIOCM_CAR | TIOCM_DSR | TIOCM_CTS;
	else
		return TIOCM_CAR | TIOCM_DSR;
}

static void
serial_s3c2410_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	/* todo - possibly remove AFC and do manual CTS */
}

static void serial_s3c2410_break_ctl(struct uart_port *port, int break_state)
{
	unsigned long flags;
	unsigned int ucon;

	spin_lock_irqsave(&port->lock, flags);

	ucon = rd_regl(port, S3C2410_UCON);

	if (break_state)
		ucon |= S3C2410_UCON_SBREAK;
	else
		ucon &= ~S3C2410_UCON_SBREAK;

	wr_regl(port, S3C2410_UCON, ucon);

	spin_unlock_irqrestore(&port->lock, flags);
}

static int serial_s3c2410_startup(struct uart_port *port)
{
	int ret;

	tx_enabled(port) = 1;
	rx_enabled(port) = 1;

	dbg("serial_s3c2410_startup: port=%p (%p)\n",
	    port, port->mapbase);

	ret = request_irq(RX_IRQ(port), serial_s3c2410_rx_chars, 0,
			  serial_s3c2410_name, port);

	if (ret != 0)
		return ret;

	ret = request_irq(TX_IRQ(port), serial_s3c2410_tx_chars, 0,
			  serial_s3c2410_name, port);

	if (ret) {
		free_irq(RX_IRQ(port), port);
		return ret;
	}

	/* the port reset code should have done the correct
	 * register setup for the port controls */

	return ret;
}

static void serial_s3c2410_shutdown(struct uart_port *port)
{
	free_irq(TX_IRQ(port), port);
	free_irq(RX_IRQ(port), port);
}

static void
serial_s3c2410_set_termios(struct uart_port *port, struct termios *termios,
			   struct termios *old)
{
	unsigned long flags;
	unsigned int baud, quot;
	unsigned int ulcon;

	/*
	 * We don't support modem control lines.
	 */
	termios->c_cflag &= ~(HUPCL | CRTSCTS | CMSPAR);
	termios->c_cflag |= CLOCAL;

	/*
	 * We don't support BREAK character recognition.
	 */
	termios->c_iflag &= ~(IGNBRK | BRKINT);

	/*
	 * Ask the core to calculate the divisor for us.
	 */
	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
	quot = uart_get_divisor(port, baud);

	switch (termios->c_cflag & CSIZE) {
	case CS5:
		dbg("config: 5bits/char\n");
		ulcon = S3C2410_LCON_CS5;
		break;
	case CS6:
		dbg("config: 6bits/char\n");
		ulcon = S3C2410_LCON_CS6;
		break;
	case CS7:
		dbg("config: 7bits/char\n");
		ulcon = S3C2410_LCON_CS7;
		break;
	case CS8:
	default:
		dbg("config: 8bits/char\n");
		ulcon = S3C2410_LCON_CS8;
		break;
	}

	if (termios->c_cflag & CSTOPB)
		ulcon |= S3C2410_LCON_STOPB;

	if (termios->c_cflag & PARENB) {
		if (!(termios->c_cflag & PARODD))
			ulcon |= S3C2410_LCON_PODD;
		else
			ulcon |= S3C2410_LCON_PEVEN;
	} else {
		ulcon |= S3C2410_LCON_PNONE;
	}

	/*
	if (port->fifosize)
	enable_fifo()
	*/

	spin_lock_irqsave(&port->lock, flags);

	dbg("setting ulcon to %08x\n", ulcon);
	//dbg("<flushing output from serial>\n");

	/* set the ulcon register */
	wr_regl(port, S3C2410_ULCON, ulcon);

	dbg("uart: ulcon = 0x%08x, ucon = 0x%08x, ufcon = 0x%08x\n",
	    rd_regl(port, S3C2410_ULCON),
	    rd_regl(port, S3C2410_UCON),
	    rd_regl(port, S3C2410_UFCON));

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

	/*
	 * Which character status flags are we interested in?
	 */
	port->read_status_mask = S3C2410_UERSTAT_OVERRUN;
	if (termios->c_iflag & INPCK)
		port->read_status_mask |= S3C2410_UERSTAT_FRAME | S3C2410_UERSTAT_PARITY;

	/*
	 * Which character status flags should we ignore?
	 */
	port->ignore_status_mask = 0;
	if (termios->c_iflag & IGNPAR)
		port->ignore_status_mask |= S3C2410_UERSTAT_OVERRUN;
	if (termios->c_iflag & IGNBRK && termios->c_iflag & IGNPAR)
		port->ignore_status_mask |= S3C2410_UERSTAT_FRAME;

	/*
	 * Ignore all characters if CREAD is not set.
	 */
	if ((termios->c_cflag & CREAD) == 0)
		port->ignore_status_mask |= RXSTAT_DUMMY_READ;

	spin_unlock_irqrestore(&port->lock, flags);
}

static const char *serial_s3c2410_type(struct uart_port *port)
{
	return port->type == PORT_S3C2410 ? "S3C2410" : NULL;
}

#define MAP_SIZE (0x100)

static void
serial_s3c2410_release_port(struct uart_port *port)
{
	release_mem_region(port->mapbase, MAP_SIZE);
}

static int
serial_s3c2410_request_port(struct uart_port *port)
{
	return request_mem_region(port->mapbase, MAP_SIZE, serial_s3c2410_name)
		!= NULL ? 0 : -EBUSY;
}

static void
serial_s3c2410_config_port(struct uart_port *port, int flags)
{
	if (flags & UART_CONFIG_TYPE &&