Loading...
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
26int fsl8250_handle_irq(struct uart_port *port)
27{
28 unsigned long flags;
29 u16 lsr, orig_lsr;
30 unsigned int iir;
31 struct uart_8250_port *up = up_to_u8250p(port);
32
33 uart_port_lock_irqsave(&up->port, &flags);
34
35 iir = port->serial_in(port, UART_IIR);
36 if (iir & UART_IIR_NO_INT) {
37 uart_port_unlock_irqrestore(&up->port, flags);
38 return 0;
39 }
40
41 /*
42 * For a single break the hardware reports LSR.BI for each character
43 * time. This is described in the MPC8313E chip errata as "General17".
44 * A typical break has a duration of 0.3s, with a 115200n8 configuration
45 * that (theoretically) corresponds to ~3500 interrupts in these 0.3s.
46 * In practise it's less (around 500) because of hardware
47 * and software latencies. The workaround recommended by the vendor is
48 * to read the RX register (to clear LSR.DR and thus prevent a FIFO
49 * aging interrupt). To prevent the irq from retriggering LSR must not be
50 * read. (This would clear LSR.BI, hardware would reassert the BI event
51 * immediately and interrupt the CPU again. The hardware clears LSR.BI
52 * when the next valid char is read.)
53 */
54 if (unlikely((iir & UART_IIR_ID) == UART_IIR_RLSI &&
55 (up->lsr_saved_flags & UART_LSR_BI))) {
56 up->lsr_saved_flags &= ~UART_LSR_BI;
57 port->serial_in(port, UART_RX);
58 uart_port_unlock_irqrestore(&up->port, flags);
59 return 1;
60 }
61
62 lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR);
63
64 /* Process incoming characters first */
65 if ((lsr & (UART_LSR_DR | UART_LSR_BI)) &&
66 (up->ier & (UART_IER_RLSI | UART_IER_RDI))) {
67 lsr = serial8250_rx_chars(up, lsr);
68 }
69
70 /* Stop processing interrupts on input overrun */
71 if ((orig_lsr & UART_LSR_OE) && (up->overrun_backoff_time_ms > 0)) {
72 unsigned long delay;
73
74 up->ier = port->serial_in(port, UART_IER);
75 if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) {
76 port->ops->stop_rx(port);
77 } else {
78 /* Keep restarting the timer until
79 * the input overrun subsides.
80 */
81 cancel_delayed_work(&up->overrun_backoff);
82 }
83
84 delay = msecs_to_jiffies(up->overrun_backoff_time_ms);
85 schedule_delayed_work(&up->overrun_backoff, delay);
86 }
87
88 serial8250_modem_status(up);
89
90 if ((lsr & UART_LSR_THRE) && (up->ier & UART_IER_THRI))
91 serial8250_tx_chars(up);
92
93 up->lsr_saved_flags |= orig_lsr & UART_LSR_BI;
94
95 uart_unlock_and_check_sysrq_irqrestore(&up->port, flags);
96
97 return 1;
98}
99EXPORT_SYMBOL_GPL(fsl8250_handle_irq);
100
101#ifdef CONFIG_ACPI
102struct fsl8250_data {
103 int line;
104};
105
106static int fsl8250_acpi_probe(struct platform_device *pdev)
107{
108 struct fsl8250_data *data;
109 struct uart_8250_port port8250;
110 struct device *dev = &pdev->dev;
111 struct resource *regs;
112
113 int ret, irq;
114
115 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
116 if (!regs) {
117 dev_err(dev, "no registers defined\n");
118 return -EINVAL;
119 }
120
121 irq = platform_get_irq(pdev, 0);
122 if (irq < 0)
123 return irq;
124
125 memset(&port8250, 0, sizeof(port8250));
126
127 ret = device_property_read_u32(dev, "clock-frequency",
128 &port8250.port.uartclk);
129 if (ret)
130 return ret;
131
132 spin_lock_init(&port8250.port.lock);
133
134 port8250.port.mapbase = regs->start;
135 port8250.port.irq = irq;
136 port8250.port.handle_irq = fsl8250_handle_irq;
137 port8250.port.type = PORT_16550A;
138 port8250.port.flags = UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF
139 | UPF_FIXED_PORT | UPF_IOREMAP
140 | UPF_FIXED_TYPE;
141 port8250.port.dev = dev;
142 port8250.port.mapsize = resource_size(regs);
143 port8250.port.iotype = UPIO_MEM;
144 port8250.port.irqflags = IRQF_SHARED;
145
146 port8250.port.membase = devm_ioremap(dev, port8250.port.mapbase,
147 port8250.port.mapsize);
148 if (!port8250.port.membase)
149 return -ENOMEM;
150
151 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
152 if (!data)
153 return -ENOMEM;
154
155 data->line = serial8250_register_8250_port(&port8250);
156 if (data->line < 0)
157 return data->line;
158
159 platform_set_drvdata(pdev, data);
160 return 0;
161}
162
163static void fsl8250_acpi_remove(struct platform_device *pdev)
164{
165 struct fsl8250_data *data = platform_get_drvdata(pdev);
166
167 serial8250_unregister_port(data->line);
168}
169
170static const struct acpi_device_id fsl_8250_acpi_id[] = {
171 { "NXP0018", 0 },
172 { },
173};
174MODULE_DEVICE_TABLE(acpi, fsl_8250_acpi_id);
175
176static struct platform_driver fsl8250_platform_driver = {
177 .driver = {
178 .name = "fsl-16550-uart",
179 .acpi_match_table = ACPI_PTR(fsl_8250_acpi_id),
180 },
181 .probe = fsl8250_acpi_probe,
182 .remove_new = fsl8250_acpi_remove,
183};
184
185module_platform_driver(fsl8250_platform_driver);
186#endif
187
188MODULE_LICENSE("GPL");
189MODULE_DESCRIPTION("Handling of Freescale specific 8250 variants");
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
26int fsl8250_handle_irq(struct uart_port *port)
27{
28 unsigned long flags;
29 u16 lsr, orig_lsr;
30 unsigned int iir;
31 struct uart_8250_port *up = up_to_u8250p(port);
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(&up->port.lock);
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(&up->port.lock);
46 return 1;
47 }
48
49 lsr = orig_lsr = up->port.serial_in(&up->port, UART_LSR);
50
51 /* Process incoming characters first */
52 if ((lsr & (UART_LSR_DR | UART_LSR_BI)) &&
53 (up->ier & (UART_IER_RLSI | UART_IER_RDI))) {
54 lsr = serial8250_rx_chars(up, lsr);
55 }
56
57 /* Stop processing interrupts on input overrun */
58 if ((orig_lsr & UART_LSR_OE) && (up->overrun_backoff_time_ms > 0)) {
59 unsigned long delay;
60
61 up->ier = port->serial_in(port, UART_IER);
62 if (up->ier & (UART_IER_RLSI | UART_IER_RDI)) {
63 port->ops->stop_rx(port);
64 } else {
65 /* Keep restarting the timer until
66 * the input overrun subsides.
67 */
68 cancel_delayed_work(&up->overrun_backoff);
69 }
70
71 delay = msecs_to_jiffies(up->overrun_backoff_time_ms);
72 schedule_delayed_work(&up->overrun_backoff, delay);
73 }
74
75 serial8250_modem_status(up);
76
77 if ((lsr & UART_LSR_THRE) && (up->ier & UART_IER_THRI))
78 serial8250_tx_chars(up);
79
80 up->lsr_saved_flags |= orig_lsr & UART_LSR_BI;
81
82 uart_unlock_and_check_sysrq_irqrestore(&up->port, flags);
83
84 return 1;
85}
86EXPORT_SYMBOL_GPL(fsl8250_handle_irq);
87
88#ifdef CONFIG_ACPI
89struct fsl8250_data {
90 int line;
91};
92
93static 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
150static 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
158static const struct acpi_device_id fsl_8250_acpi_id[] = {
159 { "NXP0018", 0 },
160 { },
161};
162MODULE_DEVICE_TABLE(acpi, fsl_8250_acpi_id);
163
164static 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
173module_platform_driver(fsl8250_platform_driver);
174#endif