| Paul Gortmaker | 9deaa53 | 2011-12-04 18:42:23 -0500 | [diff] [blame] | 1 | #include <linux/serial_reg.h> |
| 2 | #include <linux/serial_8250.h> |
| 3 | |
| 4 | #include "8250.h" |
| 5 | |
| 6 | /* |
| 7 | * Freescale 16550 UART "driver", Copyright (C) 2011 Paul Gortmaker. |
| 8 | * |
| 9 | * This program is free software; you can redistribute it and/or modify |
| 10 | * it under the terms of the GNU General Public License version 2 as |
| 11 | * published by the Free Software Foundation. |
| 12 | * |
| 13 | * This isn't a full driver; it just provides an alternate IRQ |
| 14 | * handler to deal with an errata. Everything else is just |
| 15 | * using the bog standard 8250 support. |
| 16 | * |
| 17 | * We follow code flow of serial8250_default_handle_irq() but add |
| 18 | * a check for a break and insert a dummy read on the Rx for the |
| 19 | * immediately following IRQ event. |
| 20 | * |
| 21 | * We re-use the already existing "bug handling" lsr_saved_flags |
| 22 | * field to carry the "what we just did" information from the one |
| 23 | * IRQ event to the next one. |
| 24 | */ |
| 25 | |
| 26 | int fsl8250_handle_irq(struct uart_port *port) |
| 27 | { |
| 28 | unsigned char lsr, orig_lsr; |
| 29 | unsigned long flags; |
| 30 | unsigned int iir; |
| Andy Shevchenko | b1261c8 | 2014-07-14 14:26:14 +0300 | [diff] [blame] | 31 | struct uart_8250_port *up = up_to_u8250p(port); |
| Paul Gortmaker | 9deaa53 | 2011-12-04 18:42:23 -0500 | [diff] [blame] | 32 | |
| 33 | spin_lock_irqsave(&up->port.lock, flags); |
| 34 | |
| 35 | iir = port->serial_in(port, UART_IIR); |
| 36 | if (iir & UART_IIR_NO_INT) { |
| 37 | spin_unlock_irqrestore(&up->port.lock, flags); |
| 38 | return 0; |
| 39 | } |
| 40 | |
| 41 | /* This is the WAR; if last event was BRK, then read and return */ |
| 42 | if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) { |
| 43 | up->lsr_saved_flags &= ~UART_LSR_BI; |
| 44 | port->serial_in(port, UART_RX); |
| 45 | spin_unlock_irqrestore(&up->port.lock, flags); |
| 46 | return 1; |
| 47 | } |
| 48 | |
| 49 | lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR); |
| 50 | |
| 51 | if (lsr & (UART_LSR_DR | UART_LSR_BI)) |
| 52 | lsr = serial8250_rx_chars(up, lsr); |
| 53 | |
| 54 | serial8250_modem_status(up); |
| 55 | |
| 56 | if (lsr & UART_LSR_THRE) |
| 57 | serial8250_tx_chars(up); |
| 58 | |
| 59 | up->lsr_saved_flags = orig_lsr; |
| 60 | spin_unlock_irqrestore(&up->port.lock, flags); |
| 61 | return 1; |
| 62 | } |