path: root/drivers/tty/serial/bfin_uart.c

/*
 * Blackfin On-Chip Serial Driver
 *
 * Copyright 2006-2011 Analog Devices Inc.
 *
 * Enter bugs at http://blackfin.uclinux.org/
 *
 * Licensed under the GPL-2 or later.
 */

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

#define DRIVER_NAME "bfin-uart"
#define pr_fmt(fmt) DRIVER_NAME ": " fmt

#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/gfp.h>
#include <linux/io.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 <linux/gpio.h>
#include <linux/irq.h>
#include <linux/kgdb.h>
#include <linux/slab.h>
#include <linux/dma-mapping.h>

#include <asm/portmux.h>
#include <asm/cacheflush.h>
#include <asm/dma.h>
#include <asm/bfin_serial.h>

#ifdef CONFIG_SERIAL_BFIN_MODULE
# undef CONFIG_EARLY_PRINTK
#endif

/* UART name and device definitions */
#define BFIN_SERIAL_DEV_NAME	"ttyBF"
#define BFIN_SERIAL_MAJOR	204
#define BFIN_SERIAL_MINOR	64

static struct bfin_serial_port *bfin_serial_ports[BFIN_UART_NR_PORTS];

#if defined(CONFIG_KGDB_SERIAL_CONSOLE) || \
	defined(CONFIG_KGDB_SERIAL_CONSOLE_MODULE)

# ifndef CONFIG_SERIAL_BFIN_PIO
#  error KGDB only support UART in PIO mode.
# endif

static int kgdboc_port_line;
static int kgdboc_break_enabled;
#endif
/*
 * Setup for console. Argument comes from the menuconfig
 */
#define DMA_RX_XCOUNT		512
#define DMA_RX_YCOUNT		(PAGE_SIZE / DMA_RX_XCOUNT)

#define DMA_RX_FLUSH_JIFFIES	(HZ / 50)

#ifdef CONFIG_SERIAL_BFIN_DMA
static void bfin_serial_dma_tx_chars(struct bfin_serial_port *uart);
#else
static void bfin_serial_tx_chars(struct bfin_serial_port *uart);
#endif

static void bfin_serial_reset_irda(struct uart_port *port);

#if defined(CONFIG_SERIAL_BFIN_CTSRTS) || \
	defined(CONFIG_SERIAL_BFIN_HARD_CTSRTS)
static unsigned int bfin_serial_get_mctrl(struct uart_port *port)
{
	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
	if (uart->cts_pin < 0)
		return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;

	/* CTS PIN is negative assertive. */
	if (UART_GET_CTS(uart))
		return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
	else
		return TIOCM_DSR | TIOCM_CAR;
}

static void bfin_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
	if (uart->rts_pin < 0)
		return;

	/* RTS PIN is negative assertive. */
	if (mctrl & TIOCM_RTS)
		UART_ENABLE_RTS(uart);
	else
		UART_DISABLE_RTS(uart);
}

/*
 * Handle any change of modem status signal.
 */
static irqreturn_t bfin_serial_mctrl_cts_int(int irq, void *dev_id)
{
	struct bfin_serial_port *uart = dev_id;
	unsigned int status = bfin_serial_get_mctrl(&uart->port);
#ifdef CONFIG_SERIAL_BFIN_HARD_CTSRTS
	struct tty_struct *tty = uart->port.state->port.tty;

	UART_CLEAR_SCTS(uart);
	if (tty->hw_stopped) {
		if (status) {
			tty->hw_stopped = 0;
			uart_write_wakeup(&uart->port);
		}
	} else {
		if (!status)
			tty->hw_stopped = 1;
	}
#endif
	uart_handle_cts_change(&uart->port, status & TIOCM_CTS);

	return IRQ_HANDLED;
}
#else
static unsigned int bfin_serial_get_mctrl(struct uart_port *port)
{
	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
}

static void bfin_serial_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
}
#endif

/*
 * interrupts are disabled on entry
 */
static void bfin_serial_stop_tx(struct uart_port *port)
{
	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
#ifdef CONFIG_SERIAL_BFIN_DMA
	struct circ_buf *xmit = &uart->port.state->xmit;
#endif

	while (!(UART_GET_LSR(uart) & TEMT))
		cpu_relax();

#ifdef CONFIG_SERIAL_BFIN_DMA
	disable_dma(uart->tx_dma_channel);
	xmit->tail = (xmit->tail + uart->tx_count) & (UART_XMIT_SIZE - 1);
	uart->port.icount.tx += uart->tx_count;
	uart->tx_count = 0;
	uart->tx_done = 1;
#else
#if defined(CONFIG_BF54x) || defined(CONFIG_BF60x)
	/* Clear TFI bit */
	UART_PUT_LSR(uart, TFI);
#endif
	UART_CLEAR_IER(uart, ETBEI);
#endif
}

/*
 * port is locked and interrupts are disabled
 */
static void bfin_serial_start_tx(struct uart_port *port)
{
	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;
	struct tty_struct *tty = uart->port.state->port.tty;

	/*
	 * To avoid losting RX interrupt, we reset IR function
	 * before sending data.
	 */
	if (tty->termios.c_line == N_IRDA)
		bfin_serial_reset_irda(port);

#ifdef CONFIG_SERIAL_BFIN_DMA
	if (uart->tx_done)
		bfin_serial_dma_tx_chars(uart);
#else
	UART_SET_IER(uart, ETBEI);
	bfin_serial_tx_chars(uart);
#endif
}

/*
 * Interrupts are enabled
 */
static void bfin_serial_stop_rx(struct uart_port *port)
{
	struct bfin_serial_port *uart = (struct bfin_serial_port *)port;

	UART_CLEAR_IER(uart, ERBFI);
}

/*
 * Set the modem control timer to fire immediately.
 */
static void bfin_serial_enable_ms(struct uart_port *port)
{
}


#if ANOMALY_05000363 && defined(CONFIG_SERIAL_BFIN_PIO)
# define UART_GET_ANOMALY_THRESHOLD(uart)    ((uart)->anomaly_threshold)
# define UART_SET_ANOMALY_THRESHOLD(uart, v) ((uart)->anomaly_threshold = (v))
#else
# define UART_GET_ANOMALY_THRESHOLD(uart)    0
# define UART_SET_ANOMALY_THRESHOLD(uart, v)
#endif

#ifdef CONFIG_SERIAL_BFIN_PIO
static void bfin_serial_rx_chars(struct bfin_serial_port *uart)
{
	unsigned int status, ch, flg;
	static struct timeval anomaly_start = { .tv_sec = 0 };

	status = UART_GET_LSR(uart);
	UART_CLEAR_LSR(uart);

	ch = UART_GET_CHAR(uart);
	uart->port.icount.rx++;

#if defined(CONFIG_KGDB_SERIAL_CONSOLE) || \
	defined(CONFIG_KGDB_SERIAL_CONSOLE_MODULE)
	if (kgdb_connected && kgdboc_port_line == uart->port.line
		&& kgdboc_break_enabled)
		if (ch == 0x3) {/* Ctrl + C */
			kgdb_breakpoint();
			return;
		}

	if (!uart->port.state)
		return;
#endif
	if (ANOMALY_05000363) {
		/* The BF533 (and BF561) family of processors have a nice anomaly
		 * where they continuously generate characters for a "single" break.
		 * We have to basically ignore this flood until the "next" valid
		 * character comes across.  Due to the nature of the flood, it is
		 * not possible to reli