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 * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit. 21 * Detect them by examining the OEM fields in the SPCR header, similiar to PCI 22 * quirk detection in pci_mcfg.c. 23 */ 24 static bool qdf2400_erratum_44_present(struct acpi_table_header *h) 25 { 26 if (memcmp(h->oem_id, "QCOM ", ACPI_OEM_ID_SIZE)) 27 return false; 28 29 if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE)) 30 return true; 31 32 if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) && 33 h->oem_revision == 1) 34 return true; 35 36 return false; 37 } 38 39 /** 40 * parse_spcr() - parse ACPI SPCR table and add preferred console 41 * 42 * @earlycon: set up earlycon for the console specified by the table 43 * 44 * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be 45 * defined to parse ACPI SPCR table. As a result of the parsing preferred 46 * console is registered and if @earlycon is true, earlycon is set up. 47 * 48 * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called 49 * from arch initialization code as soon as the DT/ACPI decision is made. 50 * 51 */ 52 int __init parse_spcr(bool earlycon) 53 { 54 static char opts[64]; 55 struct acpi_table_spcr *table; 56 acpi_status status; 57 char *uart; 58 char *iotype; 59 int baud_rate; 60 int err; 61 62 if (acpi_disabled) 63 return -ENODEV; 64 65 status = acpi_get_table(ACPI_SIG_SPCR, 0, 66 (struct acpi_table_header **)&table); 67 68 if (ACPI_FAILURE(status)) 69 return -ENOENT; 70 71 if (table->header.revision < 2) { 72 err = -ENOENT; 73 pr_err("wrong table version\n"); 74 goto done; 75 } 76 77 iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ? 78 "mmio" : "io"; 79 80 switch (table->interface_type) { 81 case ACPI_DBG2_ARM_SBSA_32BIT: 82 iotype = "mmio32"; 83 /* fall through */ 84 case ACPI_DBG2_ARM_PL011: 85 case ACPI_DBG2_ARM_SBSA_GENERIC: 86 case ACPI_DBG2_BCM2835: 87 uart = "pl011"; 88 break; 89 case ACPI_DBG2_16550_COMPATIBLE: 90 case ACPI_DBG2_16550_SUBSET: 91 uart = "uart"; 92 break; 93 default: 94 err = -ENOENT; 95 goto done; 96 } 97 98 switch (table->baud_rate) { 99 case 3: 100 baud_rate = 9600; 101 break; 102 case 4: 103 baud_rate = 19200; 104 break; 105 case 6: 106 baud_rate = 57600; 107 break; 108 case 7: 109 baud_rate = 115200; 110 break; 111 default: 112 err = -ENOENT; 113 goto done; 114 } 115 116 if (qdf2400_erratum_44_present(&table->header)) 117 uart = "qdf2400_e44"; 118 119 snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype, 120 table->serial_port.address, baud_rate); 121 122 pr_info("console: %s\n", opts); 123 124 if (earlycon) 125 setup_earlycon(opts); 126 127 err = add_preferred_console(uart, 0, opts + strlen(uart) + 1); 128 129 done: 130 acpi_put_table((struct acpi_table_header *)table); 131 return err; 132 } 133