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, instance: 0, out_table: (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 case ACPI_DBG2_RISCV_SBI_CON:
145 uart = "sbi";
146 break;
147 default:
148 err = -ENOENT;
149 goto done;
150 }
151
152 /*
153 * SPCR 1.09 defines Precise Baud Rate Filed contains a specific
154 * non-zero baud rate which overrides the value of the Configured
155 * Baud Rate field. If this field is zero or not present, Configured
156 * Baud Rate is used.
157 */
158 if (table->precise_baudrate)
159 baud_rate = table->precise_baudrate;
160 else switch (table->baud_rate) {
161 case 0:
162 /*
163 * SPCR 1.04 defines 0 as a preconfigured state of UART.
164 * Assume firmware or bootloader configures console correctly.
165 */
166 baud_rate = 0;
167 break;
168 case 3:
169 baud_rate = 9600;
170 break;
171 case 4:
172 baud_rate = 19200;
173 break;
174 case 6:
175 baud_rate = 57600;
176 break;
177 case 7:
178 baud_rate = 115200;
179 break;
180 default:
181 err = -ENOENT;
182 goto done;
183 }
184
185 /*
186 * If the E44 erratum is required, then we need to tell the pl011
187 * driver to implement the work-around.
188 *
189 * The global variable is used by the probe function when it
190 * creates the UARTs, whether or not they're used as a console.
191 *
192 * If the user specifies "traditional" earlycon, the qdf2400_e44
193 * console name matches the EARLYCON_DECLARE() statement, and
194 * SPCR is not used. Parameter "earlycon" is false.
195 *
196 * If the user specifies "SPCR" earlycon, then we need to update
197 * the console name so that it also says "qdf2400_e44". Parameter
198 * "earlycon" is true.
199 *
200 * For consistency, if we change the console name, then we do it
201 * for everyone, not just earlycon.
202 */
203 if (qdf2400_erratum_44_present(h: &table->header)) {
204 qdf2400_e44_present = true;
205 if (enable_earlycon)
206 uart = "qdf2400_e44";
207 }
208
209 if (xgene_8250_erratum_present(tb: table)) {
210 iotype = "mmio32";
211
212 /*
213 * For xgene v1 and v2 we don't know the clock rate of the
214 * UART so don't attempt to change to the baud rate state
215 * in the table because driver cannot calculate the dividers
216 */
217 baud_rate = 0;
218 }
219
220 if (!baud_rate) {
221 snprintf(buf: opts, size: sizeof(opts), fmt: "%s,%s,0x%llx", uart, iotype,
222 table->serial_port.address);
223 } else {
224 snprintf(buf: opts, size: sizeof(opts), fmt: "%s,%s,0x%llx,%d", uart, iotype,
225 table->serial_port.address, baud_rate);
226 }
227
228 pr_info("console: %s\n", opts);
229
230 if (enable_earlycon)
231 setup_earlycon(opts);
232
233 if (enable_console)
234 err = add_preferred_console(name: uart, idx: 0, options: opts + strlen(uart) + 1);
235 else
236 err = 0;
237done:
238 acpi_put_table(table: (struct acpi_table_header *)table);
239 return err;
240}
241