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