Commit | Line | Data |
---|---|---|
e3b3d0f5 | 1 | // SPDX-License-Identifier: GPL-2.0 |
9deaa53a PG |
2 | #include <linux/serial_reg.h> |
3 | #include <linux/serial_8250.h> | |
4 | ||
5 | #include "8250.h" | |
6 | ||
7 | /* | |
8 | * Freescale 16550 UART "driver", Copyright (C) 2011 Paul Gortmaker. | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify | |
11 | * it under the terms of the GNU General Public License version 2 as | |
12 | * published by the Free Software Foundation. | |
13 | * | |
14 | * This isn't a full driver; it just provides an alternate IRQ | |
15 | * handler to deal with an errata. Everything else is just | |
16 | * using the bog standard 8250 support. | |
17 | * | |
18 | * We follow code flow of serial8250_default_handle_irq() but add | |
19 | * a check for a break and insert a dummy read on the Rx for the | |
20 | * immediately following IRQ event. | |
21 | * | |
22 | * We re-use the already existing "bug handling" lsr_saved_flags | |
23 | * field to carry the "what we just did" information from the one | |
24 | * IRQ event to the next one. | |
25 | */ | |
26 | ||
27 | int fsl8250_handle_irq(struct uart_port *port) | |
28 | { | |
29 | unsigned char lsr, orig_lsr; | |
30 | unsigned long flags; | |
31 | unsigned int iir; | |
b1261c86 | 32 | struct uart_8250_port *up = up_to_u8250p(port); |
9deaa53a PG |
33 | |
34 | spin_lock_irqsave(&up->port.lock, flags); | |
35 | ||
36 | iir = port->serial_in(port, UART_IIR); | |
37 | if (iir & UART_IIR_NO_INT) { | |
38 | spin_unlock_irqrestore(&up->port.lock, flags); | |
39 | return 0; | |
40 | } | |
41 | ||
42 | /* This is the WAR; if last event was BRK, then read and return */ | |
43 | if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) { | |
44 | up->lsr_saved_flags &= ~UART_LSR_BI; | |
45 | port->serial_in(port, UART_RX); | |
46 | spin_unlock_irqrestore(&up->port.lock, flags); | |
47 | return 1; | |
48 | } | |
49 | ||
50 | lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR); | |
51 | ||
52 | if (lsr & (UART_LSR_DR | UART_LSR_BI)) | |
53 | lsr = serial8250_rx_chars(up, lsr); | |
54 | ||
55 | serial8250_modem_status(up); | |
56 | ||
57 | if (lsr & UART_LSR_THRE) | |
58 | serial8250_tx_chars(up); | |
59 | ||
60 | up->lsr_saved_flags = orig_lsr; | |
61 | spin_unlock_irqrestore(&up->port.lock, flags); | |
62 | return 1; | |
63 | } | |
bd63acf9 | 64 | EXPORT_SYMBOL_GPL(fsl8250_handle_irq); |