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 */
22 bool qdf2400_e44_present;
23 EXPORT_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 */
qdf2400_erratum_44_present(struct acpi_table_header * h)30 static 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 */
xgene_8250_erratum_present(struct acpi_table_spcr * tb)50 static 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 *
75 * @enable_earlycon: set up earlycon for the console specified by the table
76 * @enable_console: setup the console specified by the table.
77 *
78 * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
79 * defined to parse ACPI SPCR table. As a result of the parsing preferred
80 * console is registered and if @enable_earlycon is true, earlycon is set up.
81 * If @enable_console is true the system console is also configured.
82 *
83 * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
84 * from arch initialization code as soon as the DT/ACPI decision is made.
85 *
86 */
acpi_parse_spcr(bool enable_earlycon,bool enable_console)87 int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)
88 {
89 static char opts[64];
90 struct acpi_table_spcr *table;
91 acpi_status status;
92 char *uart;
93 char *iotype;
94 int baud_rate;
95 int err;
96
97 if (acpi_disabled)
98 return -ENODEV;
99
100 status = acpi_get_table(ACPI_SIG_SPCR, 0,
101 (struct acpi_table_header **)&table);
102
103 if (ACPI_FAILURE(status))
104 return -ENOENT;
105
106 if (table->header.revision < 2)
107 pr_info("SPCR table version %d\n", table->header.revision);
108
109 if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
110 switch (ACPI_ACCESS_BIT_WIDTH((
111 table->serial_port.access_width))) {
112 default:
113 pr_err("Unexpected SPCR Access Width. Defaulting to byte size\n");
114 fallthrough;
115 case 8:
116 iotype = "mmio";
117 break;
118 case 16:
119 iotype = "mmio16";
120 break;
121 case 32:
122 iotype = "mmio32";
123 break;
124 }
125 } else
126 iotype = "io";
127
128 switch (table->interface_type) {
129 case ACPI_DBG2_ARM_SBSA_32BIT:
130 iotype = "mmio32";
131 fallthrough;
132 case ACPI_DBG2_ARM_PL011:
133 case ACPI_DBG2_ARM_SBSA_GENERIC:
134 case ACPI_DBG2_BCM2835:
135 uart = "pl011";
136 break;
137 case ACPI_DBG2_16550_COMPATIBLE:
138 case ACPI_DBG2_16550_SUBSET:
139 case ACPI_DBG2_16550_WITH_GAS:
140 uart = "uart";
141 break;
142 default:
143 err = -ENOENT;
144 goto done;
145 }
146
147 switch (table->baud_rate) {
148 case 0:
149 /*
150 * SPCR 1.04 defines 0 as a preconfigured state of UART.
151 * Assume firmware or bootloader configures console correctly.
152 */
153 baud_rate = 0;
154 break;
155 case 3:
156 baud_rate = 9600;
157 break;
158 case 4:
159 baud_rate = 19200;
160 break;
161 case 6:
162 baud_rate = 57600;
163 break;
164 case 7:
165 baud_rate = 115200;
166 break;
167 default:
168 err = -ENOENT;
169 goto done;
170 }
171
172 /*
173 * If the E44 erratum is required, then we need to tell the pl011
174 * driver to implement the work-around.
175 *
176 * The global variable is used by the probe function when it
177 * creates the UARTs, whether or not they're used as a console.
178 *
179 * If the user specifies "traditional" earlycon, the qdf2400_e44
180 * console name matches the EARLYCON_DECLARE() statement, and
181 * SPCR is not used. Parameter "earlycon" is false.
182 *
183 * If the user specifies "SPCR" earlycon, then we need to update
184 * the console name so that it also says "qdf2400_e44". Parameter
185 * "earlycon" is true.
186 *
187 * For consistency, if we change the console name, then we do it
188 * for everyone, not just earlycon.
189 */
190 if (qdf2400_erratum_44_present(&table->header)) {
191 qdf2400_e44_present = true;
192 if (enable_earlycon)
193 uart = "qdf2400_e44";
194 }
195
196 if (xgene_8250_erratum_present(table)) {
197 iotype = "mmio32";
198
199 /* for xgene v1 and v2 we don't know the clock rate of the
200 * UART so don't attempt to change to the baud rate state
201 * in the table because driver cannot calculate the dividers
202 */
203 baud_rate = 0;
204 }
205
206 if (!baud_rate) {
207 snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype,
208 table->serial_port.address);
209 } else {
210 snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
211 table->serial_port.address, baud_rate);
212 }
213
214 pr_info("console: %s\n", opts);
215
216 if (enable_earlycon)
217 setup_earlycon(opts);
218
219 if (enable_console)
220 err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
221 else
222 err = 0;
223 done:
224 acpi_put_table((struct acpi_table_header *)table);
225 return err;
226 }
227