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

/*
 *  Based on drivers/serial/8250.c by Russell King.
 *
 *  Author:	Nicolas Pitre
 *  Created:	Feb 20, 2003
 *  Copyright:	(C) 2003 Monta Vista Software, Inc.
 *
 * 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.
 *
 * Note 1: This driver is made separate from the already too overloaded
 * 8250.c because it needs some kirks of its own and that'll make it
 * easier to add DMA support.
 *
 * Note 2: I'm too sick of device allocation policies for serial ports.
 * If someone else wants to request an "official" allocation of major/minor
 * for this driver please be my guest.  And don't forget that new hardware
 * to come from Intel might have more than 3 or 4 of those UARTs.  Let's
 * hope for a better port registration and dynamic device allocation scheme
 * with the serial core maintainer satisfaction to appear soon.
 */


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

#include <linux/module.h>
#include <linux/ioport.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/serial_reg.h>
#include <linux/circ_buf.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial_core.h>
#include <linux/clk.h>
#include <linux/io.h>
#include <linux/slab.h>

#define PXA_NAME_LEN		8

struct uart_pxa_port {
	struct uart_port        port;
	unsigned char           ier;
	unsigned char           lcr;
	unsigned char           mcr;
	unsigned int            lsr_break_flag;
	struct clk		*clk;
	char			name[PXA_NAME_LEN];
};

static inline unsigned int serial_in(struct uart_pxa_port *up, int offset)
{
	offset <<= 2;
	return readl(up->port.membase + offset);
}

static inline void serial_out(struct uart_pxa_port *up, int offset, int value)
{
	offset <<= 2;
	writel(value, up->port.membase + offset);
}

static void serial_pxa_enable_ms(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

	up->ier |= UART_IER_MSI;
	serial_out(up, UART_IER, up->ier);
}

static void serial_pxa_stop_tx(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

	if (up->ier & UART_IER_THRI) {
		up->ier &= ~UART_IER_THRI;
		serial_out(up, UART_IER, up->ier);
	}
}

static void serial_pxa_stop_rx(struct uart_port *port)
{
	struct uart_pxa_port *up = (struct uart_pxa_port *)port;

	up->ier &= ~UART_IER_RLSI;
	up->port.read_status_mask &= ~UART_LSR_DR;
	serial_out(up, UART_IER, up->ier);
}

static inline void receive_chars(struct uart_pxa_port *up, int *status)
{
	unsigned int ch, flag;
	int max_count = 256;

	do {
		/* work around Errata #20 according to
		 * Intel(R) PXA27x Processor Family
		 * Specification Update (May 2005)
		 *
		 * Step 2
		 * Disable the Reciever Time Out Interrupt via IER[RTOEI]
		 */
		up->ier &= ~UART_IER_RTOIE;
		serial_out(up, UART_IER, up->ier);

		ch = serial_in(up, UART_RX);
		flag = TTY_NORMAL;
		up->port.icount.rx++;

		if (unlikely(*status & (UART_LSR_BI | UART_LSR_PE |
				       UART_LSR_FE | UART_LSR_OE))) {
			/*
			 * For statistics only
			 */
			if (*status & UART_LSR_BI) {
				*status &= ~(UART_LSR_FE | UART_LSR_PE);
				up->port.icount.brk++;
				/*
				 * We do the SysRQ and SAK checking
				 * here because otherwise the break
				 * may get masked by ignore_status_mask
				 * or read_status_mask.
				 */
				if (uart_handle_break(&up->port))
					goto ignore_char;
			} else if (*status & UART_LSR_PE)
				up->port.icount.parity++;
			else if (*status & UART_LSR_FE)
				up->port.icount.frame++;
			if (*status & UART_LSR_OE)
				up->port.icount.overrun++;

			/*
			 * Mask off conditions which should be ignored.
			 */
			*status &= up->port.read_status_mask;

#ifdef CONFIG_SERIAL_PXA_CONSOLE
			if (up->port.line == up->port.cons->index) {
				/* Recover the break flag from console xmit */
				*status |= up->lsr_break_flag;
				up->lsr_break_flag = 0;
			}
#endif
			if (*status & UART_LSR_BI) {
				flag = TTY_BREAK;
			} else if (*status & UART_LSR_PE)
				flag = TTY_PARITY;
			else if (*status & UART_LSR_FE)
				flag = TTY_FRAME;
		}

		if (uart_handle_sysrq_char(&up->port, ch))
			goto <