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 */
 22bool qdf2400_e44_present;
 23EXPORT_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 */
 30static 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 */
 50static 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 */
 87int __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			/* fall through */
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		/* fall through */
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;
222done:
223	acpi_put_table((struct acpi_table_header *)table);
224	return err;
225}