summaryrefslogtreecommitdiffstats
path: root/drivers/acpi/spcr.c
blob: 2b5d0fac81f072a7649f97e402443da643867dd0 (plain)
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
/*
 * Copyright (c) 2012, Intel Corporation
 * Copyright (c) 2015, Red Hat, Inc.
 * Copyright (c) 2015, 2016 Linaro Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#define pr_fmt(fmt) "ACPI: SPCR: " fmt

#include <linux/acpi.h>
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/serial_core.h>

/*
 * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
 * Detect them by examining the OEM fields in the SPCR header, similiar to PCI
 * quirk detection in pci_mcfg.c.
 */
static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
{
	if (memcmp(h->oem_id, "QCOM  ", ACPI_OEM_ID_SIZE))
		return false;

	if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
		return true;

	if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
			h->oem_revision == 0)
		return true;

	return false;
}

/**
 * parse_spcr() - parse ACPI SPCR table and add preferred console
 *
 * @earlycon: set up earlycon for the console specified by the table
 *
 * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
 * defined to parse ACPI SPCR table.  As a result of the parsing preferred
 * console is registered and if @earlycon is true, earlycon is set up.
 *
 * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
 * from arch inintialization code as soon as the DT/ACPI decision is made.
 *
 */
int __init parse_spcr(bool earlycon)
{
	static char opts[64];
	struct acpi_table_spcr *table;
	acpi_status status;
	char *uart;
	char *iotype;
	int baud_rate;
	int err;

	if (acpi_disabled)
		return -ENODEV;

	status = acpi_get_table(ACPI_SIG_SPCR, 0,
				(struct acpi_table_header **)&table);

	if (ACPI_FAILURE(status))
		return -ENOENT;

	if (table->header.revision < 2) {
		err = -ENOENT;
		pr_err("wrong table version\n");
		goto done;
	}

	iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ?
			"mmio" : "io";

	switch (table->interface_type) {
	case ACPI_DBG2_ARM_SBSA_32BIT:
		iotype = "mmio32";
		/* fall through */
	case ACPI_DBG2_ARM_PL011:
	case ACPI_DBG2_ARM_SBSA_GENERIC:
	case ACPI_DBG2_BCM2835:
		uart = "pl011";
		break;
	case ACPI_DBG2_16550_COMPATIBLE:
	case ACPI_DBG2_16550_SUBSET:
		uart = "uart";
		break;
	default:
		err = -ENOENT;
		goto done;
	}

	switch (table->baud_rate) {
	case 3:
		baud_rate = 9600;
		break;
	case 4:
		baud_rate = 19200;
		break;
	case 6:
		baud_rate = 57600;
		break;
	case 7:
		baud_rate = 115200;
		break;
	default:
		err = -ENOENT;
		goto done;
	}

	if (qdf2400_erratum_44_present(&table->header))
		uart = "qdf2400_e44";

	snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
		 table->serial_port.address, baud_rate);

	pr_info("console: %s\n", opts);

	if (earlycon)
		setup_earlycon(opts);

	err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);

done:
	acpi_put_table((struct acpi_table_header *)table);
	return err;
}