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 */ 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 */ 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 */ 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 u32 bit_width = table->serial_port.access_width; 111 112 if (bit_width > ACPI_ACCESS_BIT_MAX) { 113 pr_err("Unacceptable wide SPCR Access Width. Defaulting to byte size\n"); 114 bit_width = ACPI_ACCESS_BIT_DEFAULT; 115 } 116 switch (ACPI_ACCESS_BIT_WIDTH((bit_width))) { 117 default: 118 pr_err("Unexpected SPCR Access Width. Defaulting to byte size\n"); 119 fallthrough; 120 case 8: 121 iotype = "mmio"; 122 break; 123 case 16: 124 iotype = "mmio16"; 125 break; 126 case 32: 127 iotype = "mmio32"; 128 break; 129 } 130 } else 131 iotype = "io"; 132 133 switch (table->interface_type) { 134 case ACPI_DBG2_ARM_SBSA_32BIT: 135 iotype = "mmio32"; 136 fallthrough; 137 case ACPI_DBG2_ARM_PL011: 138 case ACPI_DBG2_ARM_SBSA_GENERIC: 139 case ACPI_DBG2_BCM2835: 140 uart = "pl011"; 141 break; 142 case ACPI_DBG2_16550_COMPATIBLE: 143 case ACPI_DBG2_16550_SUBSET: 144 case ACPI_DBG2_16550_WITH_GAS: 145 uart = "uart"; 146 break; 147 default: 148 err = -ENOENT; 149 goto done; 150 } 151 152 switch (table->baud_rate) { 153 case 0: 154 /* 155 * SPCR 1.04 defines 0 as a preconfigured state of UART. 156 * Assume firmware or bootloader configures console correctly. 157 */ 158 baud_rate = 0; 159 break; 160 case 3: 161 baud_rate = 9600; 162 break; 163 case 4: 164 baud_rate = 19200; 165 break; 166 case 6: 167 baud_rate = 57600; 168 break; 169 case 7: 170 baud_rate = 115200; 171 break; 172 default: 173 err = -ENOENT; 174 goto done; 175 } 176 177 /* 178 * If the E44 erratum is required, then we need to tell the pl011 179 * driver to implement the work-around. 180 * 181 * The global variable is used by the probe function when it 182 * creates the UARTs, whether or not they're used as a console. 183 * 184 * If the user specifies "traditional" earlycon, the qdf2400_e44 185 * console name matches the EARLYCON_DECLARE() statement, and 186 * SPCR is not used. Parameter "earlycon" is false. 187 * 188 * If the user specifies "SPCR" earlycon, then we need to update 189 * the console name so that it also says "qdf2400_e44". Parameter 190 * "earlycon" is true. 191 * 192 * For consistency, if we change the console name, then we do it 193 * for everyone, not just earlycon. 194 */ 195 if (qdf2400_erratum_44_present(&table->header)) { 196 qdf2400_e44_present = true; 197 if (enable_earlycon) 198 uart = "qdf2400_e44"; 199 } 200 201 if (xgene_8250_erratum_present(table)) { 202 iotype = "mmio32"; 203 204 /* for xgene v1 and v2 we don't know the clock rate of the 205 * UART so don't attempt to change to the baud rate state 206 * in the table because driver cannot calculate the dividers 207 */ 208 baud_rate = 0; 209 } 210 211 if (!baud_rate) { 212 snprintf(opts, sizeof(opts), "%s,%s,0x%llx", uart, iotype, 213 table->serial_port.address); 214 } else { 215 snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype, 216 table->serial_port.address, baud_rate); 217 } 218 219 pr_info("console: %s\n", opts); 220 221 if (enable_earlycon) 222 setup_earlycon(opts); 223 224 if (enable_console) 225 err = add_preferred_console(uart, 0, opts + strlen(uart) + 1); 226 else 227 err = 0; 228 done: 229 acpi_put_table((struct acpi_table_header *)table); 230 return err; 231 } 232