1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (c) 2012, Intel Corporation
4 * Copyright (c) 2015, Red Hat, Inc.
5 * Copyright (c) 2015, 2016 Linaro Ltd.
6 */
7
8#define pr_fmt(fmt) "ACPI: SPCR: " fmt
9
10#include <linux/acpi.h>
11#include <linux/console.h>
12#include <linux/kernel.h>
13#include <linux/serial_core.h>
14
15/*
16 * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
17 * occasionally getting stuck as 1. To avoid the potential for a hang, check
18 * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
19 * implementations, so only do so if an affected platform is detected in
20 * acpi_parse_spcr().
21 */
22bool qdf2400_e44_present;
23EXPORT_SYMBOL(qdf2400_e44_present);
24
25/*
26 * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
27 * Detect them by examining the OEM fields in the SPCR header, similar to PCI
28 * quirk detection in pci_mcfg.c.
29 */
30static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
31{
32	if (memcmp(h->oem_id, "QCOM  ", ACPI_OEM_ID_SIZE))
33		return false;
34
35	if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
36		return true;
37
38	if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
39			h->oem_revision == 1)
40		return true;
41
42	return false;
43}
44
45/*
46 * APM X-Gene v1 and v2 UART hardware is an 16550 like device but has its
47 * register aligned to 32-bit. In addition, the BIOS also encoded the
48 * access width to be 8 bits. This function detects this errata condition.
49 */
50static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb)
51{
52	bool xgene_8250 = false;
53
54	if (tb->interface_type != ACPI_DBG2_16550_COMPATIBLE)
55		return false;
56
57	if (memcmp(tb->header.oem_id, "APMC0D", ACPI_OEM_ID_SIZE) &&
58	    memcmp(tb->header.oem_id, "HPE   ", ACPI_OEM_ID_SIZE))
59		return false;
60
61	if (!memcmp(tb->header.oem_table_id, "XGENESPC",
62	    ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 0)
63		xgene_8250 = true;
64
65	if (!memcmp(tb->header.oem_table_id, "ProLiant",
66	    ACPI_OEM_TABLE_ID_SIZE) && tb->header.oem_revision == 1)
67		xgene_8250 = true;
68
69	return xgene_8250;
70}
71
72/**
73 * acpi_parse_spcr() - parse ACPI SPCR table and add preferred console
74 * @enable_earlycon: set up earlycon for the console specified by the table
75 * @enable_console: setup the console specified by the table.
76 *
77 * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
78 * defined to parse ACPI SPCR table.  As a result of the parsing preferred
79 * console is registered and if @enable_earlycon is true, earlycon is set up.
80 * If @enable_console is true the system console is also configured.
81 *
82 * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
83 * from arch initialization code as soon as the DT/ACPI decision is made.
84 */
85int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)
86{
87	static char opts[64];
88	struct acpi_table_spcr *table;
89	acpi_status status;
90	char *uart;
91	char *iotype;
92	int baud_rate;
93	int err;
94
95	if (acpi_disabled)
96		return -ENODEV;
97
98	status = acpi_get_table(ACPI_SIG_SPCR, 0, (struct acpi_table_header **)&table);
99	if (ACPI_FAILURE(status))
100		return -ENOENT;
101
102	if (table->header.revision < 2)
103		pr_info("SPCR table version %d\n", table->header.revision);
104
105	if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
106		u32 bit_width = table->serial_port.access_width;
107
108		if (bit_width > ACPI_ACCESS_BIT_MAX) {
109			pr_err(FW_BUG "Unacceptable wide SPCR Access Width. Defaulting to byte size\n");
110			bit_width = ACPI_ACCESS_BIT_DEFAULT;
111		}
112		switch (ACPI_ACCESS_BIT_WIDTH((bit_width))) {
113		default:
114			pr_err(FW_BUG "Unexpected SPCR Access Width. Defaulting to byte size\n");
115			fallthrough;
116		case 8:
117			iotype = "mmio";
118			break;
119		case 16:
120			iotype = "mmio16";
121			break;
122		case 32:
123			iotype = "mmio32";
124			break;
125		}
126	} else
127		iotype = "io";
128
129	switch (table->interface_type) {
130	case ACPI_DBG2_ARM_SBSA_32BIT:
131		iotype = "mmio32";
132		fallthrough;
133	case ACPI_DBG2_ARM_PL011:
134	case ACPI_DBG2_ARM_SBSA_GENERIC:
135	case ACPI_DBG2_BCM2835:
136		uart = "pl011";
137		break;
138	case ACPI_DBG2_16550_COMPATIBLE:
139	case ACPI_DBG2_16550_SUBSET:
140	case ACPI_DBG2_16550_WITH_GAS:
141	case ACPI_DBG2_16550_NVIDIA:
142		uart = "uart";
143		break;
144	default:
145		err = -ENOENT;
146		goto done;
147	}
148
149	switch (table->baud_rate) {
150	case 0:
151		/*
152		 * SPCR 1.04 defines 0 as a preconfigured state of UART.
153		 * Assume firmware or bootloader configures console correctly.
154		 */
155		baud_rate = 0;
156		break;
157	case 3:
158		baud_rate = 9600;
159		break;
160	case 4:
161		baud_rate = 19200;
162		break;
163	case 6:
164		baud_rate = 57600;
165		break;
166	case 7:
167		baud_rate = 115200;
168		break;
169	default:
170		err = -ENOENT;
171		goto done;
172	}
173
174	/*
175	 * If the E44 erratum is required, then we need to tell the pl011
176	 * driver to implement the work-around.
177	 *
178	 * The global variable is used by the probe function when it
179	 * creates the UARTs, whether or not they're used as a console.
180	 *
181	 * If the user specifies "traditional" earlycon, the qdf2400_e44
182	 * console name matches the EARLYCON_DECLARE() statement, and
183	 * SPCR is not used.  Parameter "earlycon" is false.
184	 *
185	 * If the user specifies "SPCR" earlycon, then we need to update
186	 * the console name so that it also says "qdf2400_e44".  Parameter
187	 * "earlycon" is true.
188	 *
189	 * For consistency, if we change the console name, then we do it
190	 * for everyone, not just earlycon.
191	 */
192	if (qdf2400_erratum_44_present(&table->header)) {
193		qdf2400_e44_present = true;
194		if (enable_earlycon)
195			uart = "qdf2400_e44";
196	}
197
198	if (xgene_8250_erratum_present(table)) {
199		iotype = "mmio32";
200
201		/*
202		 * For xgene v1 and v2 we don't know the clock rate of the
203		 * UART so don't attempt to change to the baud rate state
204		 * in the table because driver cannot calculate the dividers
205		 */
206		baud_rate = 0;
207	}
208
209	if (!baud_rate) {
210		snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype,
211			 table->serial_port.address);
212	} else {
213		snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
214			 table->serial_port.address, baud_rate);
215	}
216
217	pr_info("console: %s\n", opts);
218
219	if (enable_earlycon)
220		setup_earlycon(opts);
221
222	if (enable_console)
223		err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
224	else
225		err = 0;
226done:
227	acpi_put_table((struct acpi_table_header *)table);
228	return err;
229}
230