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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 | * | |
9deaa53a PG |
10 | * This isn't a full driver; it just provides an alternate IRQ |
11 | * handler to deal with an errata. Everything else is just | |
12 | * using the bog standard 8250 support. | |
13 | * | |
14 | * We follow code flow of serial8250_default_handle_irq() but add | |
15 | * a check for a break and insert a dummy read on the Rx for the | |
16 | * immediately following IRQ event. | |
17 | * | |
18 | * We re-use the already existing "bug handling" lsr_saved_flags | |
19 | * field to carry the "what we just did" information from the one | |
20 | * IRQ event to the next one. | |
21 | */ | |
22 | ||
23 | int fsl8250_handle_irq(struct uart_port *port) | |
24 | { | |
25 | unsigned char lsr, orig_lsr; | |
26 | unsigned long flags; | |
27 | unsigned int iir; | |
b1261c86 | 28 | struct uart_8250_port *up = up_to_u8250p(port); |
9deaa53a PG |
29 | |
30 | spin_lock_irqsave(&up->port.lock, flags); | |
31 | ||
32 | iir = port->serial_in(port, UART_IIR); | |
33 | if (iir & UART_IIR_NO_INT) { | |
34 | spin_unlock_irqrestore(&up->port.lock, flags); | |
35 | return 0; | |
36 | } | |
37 | ||
38 | /* This is the WAR; if last event was BRK, then read and return */ | |
39 | if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) { | |
40 | up->lsr_saved_flags &= ~UART_LSR_BI; | |
41 | port->serial_in(port, UART_RX); | |
42 | spin_unlock_irqrestore(&up->port.lock, flags); | |
43 | return 1; | |
44 | } | |
45 | ||
46 | lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR); | |
47 | ||
886979da DD |
48 | /* Process incoming characters first */ |
49 | if ((lsr & (UART_LSR_DR | UART_LSR_BI)) && | |
50 | (up->ier & (UART_IER_RLSI | UART_IER_RDI))) { | |
9deaa53a | 51 | lsr = serial8250_rx_chars(up, lsr); |
886979da DD |
52 | } |
53 | ||
54 | /* Stop processing interrupts on input overrun */ | |
55 | if ((orig_lsr & UART_LSR_OE) && (up->overrun_backoff_time_ms > 0)) { | |
56 | unsigned long delay; | |
57 | ||
58 | up->ier = port->serial_in(port, UART_IER); | |
59 | if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) { | |
60 | port->ops->stop_rx(port); | |
61 | } else { | |
62 | /* Keep restarting the timer until | |
63 | * the input overrun subsides. | |
64 | */ | |
65 | cancel_delayed_work(&up->overrun_backoff); | |
66 | } | |
67 | ||
68 | delay = msecs_to_jiffies(up->overrun_backoff_time_ms); | |
69 | schedule_delayed_work(&up->overrun_backoff, delay); | |
70 | } | |
9deaa53a PG |
71 | |
72 | serial8250_modem_status(up); | |
73 | ||
74 | if (lsr & UART_LSR_THRE) | |
75 | serial8250_tx_chars(up); | |
76 | ||
77 | up->lsr_saved_flags = orig_lsr; | |
78 | spin_unlock_irqrestore(&up->port.lock, flags); | |
79 | return 1; | |
80 | } | |
bd63acf9 | 81 | EXPORT_SYMBOL_GPL(fsl8250_handle_irq); |