1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
// SPDX-License-Identifier: GPL-2.0
/*
* Freescale 16550 UART "driver", Copyright (C) 2011 Paul Gortmaker.
* Copyright 2020 NXP
* Copyright 2020 Puresoftware Ltd.
*
* This isn't a full driver; it just provides an alternate IRQ
* handler to deal with an errata and provide ACPI wrapper.
* Everything else is just using the bog standard 8250 support.
*
* We follow code flow of serial8250_default_handle_irq() but add
* a check for a break and insert a dummy read on the Rx for the
* immediately following IRQ event.
*
* We re-use the already existing "bug handling" lsr_saved_flags
* field to carry the "what we just did" information from the one
* IRQ event to the next one.
*/
#include <linux/acpi.h>
#include <linux/serial_reg.h>
#include <linux/serial_8250.h>
#include "8250.h"
struct fsl8250_data {
int line;
};
int fsl8250_handle_irq(struct uart_port *port)
{
unsigned char lsr, orig_lsr;
unsigned long flags;
unsigned int iir;
struct uart_8250_port *up = up_to_u8250p(port);
spin_lock_irqsave(&up->port.lock, flags);
iir = port->serial_in(port, UART_IIR);
if (iir & UART_IIR_NO_INT) {
spin_unlock(&up->port.lock);
return 0;
}
/* This is the WAR; if last event was BRK, then read and return */
if (unlikely(up->lsr_saved_flags & UART_LSR_BI)) {
up->lsr_saved_flags &= ~UART_LSR_BI;
port->serial_in(port, UART_RX);
spin_unlock(&up->port.lock);
return 1;
}
lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR);
/* Process incoming characters first */
if ((lsr & (UART_LSR_DR | UART_LSR_BI)) &&
(up->ier & (UART_IER_RLSI | UART_IER_RDI))) {
lsr = serial8250_rx_chars(up, lsr);
}
/* Stop processing interrupts on input overrun */
if ((orig_lsr & UART_LSR_OE) && (up->overrun_backoff_time_ms > 0)) {
unsigned long delay;
up->ier = port->serial_in(port, UART_IER);
if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) {
port->ops->stop_rx(port);
} else {
/* Keep restarting the timer until
* the input overrun subsides.
*/
cancel_delayed_work(&up->overrun_backoff);
}
delay = msecs_to_jiffies(up->overrun_backoff_time_ms);
schedule_delayed_work(&up->overrun_backoff, delay);
}
serial8250_modem_status(up);
if ((lsr & UART_LSR_THRE) && (up->ier & UART_IER_THRI))
serial8250_tx_chars(up);
up->lsr_saved_flags = orig_lsr;
uart_unlock_and_check_sysrq_irqrestore(&up->port, flags);
return 1;
}
EXPORT_SYMBOL_GPL(fsl8250_handle_irq);
#ifdef CONFIG_ACPI
static int fsl8250_acpi_probe(struct platform_device *pdev)
{
struct fsl8250_data *data;
struct uart_8250_port port8250;
struct device *dev = &pdev->dev;
struct resource *regs;
int ret, irq;
regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!regs) {
dev_err(dev, "no registers defined\n");
return -EINVAL;
}
irq = platform_get_irq(pdev, 0);
if (irq < 0)
return irq;
memset(&port8250, 0, sizeof(port8250));
ret = device_property_read_u32(dev, "clock-frequency",
&port8250.port.uartclk);
if (ret)
return ret;
spin_lock_init(&port8250.port.lock);
port8250.port.mapbase = regs->start;
port8250.port.irq = irq;
port8250.port.handle_irq = fsl8250_handle_irq;
port8250.port.type = PORT_16550A;
port8250.port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF
| UPF_FIXED_PORT | UPF_IOREMAP
| UPF_FIXED_TYPE;
port8250.port.dev = dev;
port8250.port.mapsize = resource_size(regs);
port8250.port.iotype = UPIO_MEM;
port8250.port.irqflags = IRQF_SHARED;
port8250.port.membase = devm_ioremap(dev, port8250.port.mapbase,
port8250.port.mapsize);
if (!port8250.port.membase)
return -ENOMEM;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
data->line = serial8250_register_8250_port(&port8250);
if (data->line < 0)
return data->line;
platform_set_drvdata(pdev, data);
return 0;
}
static int fsl8250_acpi_remove(struct platform_device *pdev)
{
struct fsl8250_data *data = platform_get_drvdata(pdev);
serial8250_unregister_port(data->line);
return 0;
}
static const struct acpi_device_id fsl_8250_acpi_id[] = {
{ "NXP0018", 0 },
{ },
};
MODULE_DEVICE_TABLE(acpi, fsl_8250_acpi_id);
static struct platform_driver fsl8250_platform_driver = {
.driver = {
.name = "fsl-16550-uart",
.acpi_match_table = ACPI_PTR(fsl_8250_acpi_id),
},
.probe = fsl8250_acpi_probe,
.remove = fsl8250_acpi_remove,
};
module_platform_driver(fsl8250_platform_driver);
#endif
|
