drivers/acpi/spcr.c

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