drivers/acpi/spcr.c

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