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