19deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker#include <linux/serial_reg.h> 29deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker#include <linux/serial_8250.h> 39deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 49deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker#include "8250.h" 59deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 69deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker/* 79deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * Freescale 16550 UART "driver", Copyright (C) 2011 Paul Gortmaker. 89deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * 99deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * This program is free software; you can redistribute it and/or modify 109deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * it under the terms of the GNU General Public License version 2 as 119deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * published by the Free Software Foundation. 129deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * 139deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * This isn't a full driver; it just provides an alternate IRQ 149deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * handler to deal with an errata. Everything else is just 159deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * using the bog standard 8250 support. 169deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * 179deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * We follow code flow of serial8250_default_handle_irq() but add 189deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * a check for a break and insert a dummy read on the Rx for the 199deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * immediately following IRQ event. 209deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * 219deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * We re-use the already existing "bug handling" lsr_saved_flags 229deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * field to carry the "what we just did" information from the one 239deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker * IRQ event to the next one. 249deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker */ 259deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 269deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmakerint fsl8250_handle_irq(struct uart_port *port) 279deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker{ 289deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker unsigned char lsr, orig_lsr; 299deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker unsigned long flags; 309deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker unsigned int iir; 319deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker struct uart_8250_port *up = 329deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker container_of(port, struct uart_8250_port, port); 339deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 349deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker spin_lock_irqsave(&up->port.lock, flags); 359deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 369deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker iir = port->serial_in(port, UART_IIR); 379deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker if (iir & UART_IIR_NO_INT) { 389deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker spin_unlock_irqrestore(&up->port.lock, flags); 399deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker return 0; 409deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker } 419deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 429deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker /* This is the WAR; if last event was BRK, then read and return */ 439deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) { 449deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker up->lsr_saved_flags &= ~UART_LSR_BI; 459deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker port->serial_in(port, UART_RX); 469deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker spin_unlock_irqrestore(&up->port.lock, flags); 479deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker return 1; 489deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker } 499deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 509deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR); 519deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 529deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker if (lsr & (UART_LSR_DR | UART_LSR_BI)) 539deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker lsr = serial8250_rx_chars(up, lsr); 549deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 559deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker serial8250_modem_status(up); 569deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 579deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker if (lsr & UART_LSR_THRE) 589deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker serial8250_tx_chars(up); 599deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker 609deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker up->lsr_saved_flags = orig_lsr; 619deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker spin_unlock_irqrestore(&up->port.lock, flags); 629deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker return 1; 639deaa53ac7fa373623123aa4f18828dd62292b1aPaul Gortmaker} 64