[mirror_ubuntu-zesty-kernel.git] / drivers / acpi / spcr.c

/*
 * Copyright (c) 2012, Intel Corporation
 * Copyright (c) 2015, Red Hat, Inc.
 * Copyright (c) 2015, 2016 Linaro Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 *
 */

#define pr_fmt(fmt) "ACPI: SPCR: " fmt

#include <linux/acpi.h>
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/serial_core.h>

/*
 * Erratum 44 for QDF2432v1 and QDF2400v1 SoCs describes the BUSY bit as
 * occasionally getting stuck as 1. To avoid the potential for a hang, check
 * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART
 * implementations, so only do so if an affected platform is detected in
 * parse_spcr().
 */
bool qdf2400_e44_present;
EXPORT_SYMBOL(qdf2400_e44_present);

/*
 * Some Qualcomm Datacenter Technologies SoCs have a defective UART BUSY bit.
 * Detect them by examining the OEM fields in the SPCR header, similiar to PCI
 * quirk detection in pci_mcfg.c.
 */
static bool qdf2400_erratum_44_present(struct acpi_table_header *h)
{
	if (memcmp(h->oem_id, "QCOM  ", ACPI_OEM_ID_SIZE))
		return false;

	if (!memcmp(h->oem_table_id, "QDF2432 ", ACPI_OEM_TABLE_ID_SIZE))
		return true;

	if (!memcmp(h->oem_table_id, "QDF2400 ", ACPI_OEM_TABLE_ID_SIZE) &&
			h->oem_revision == 1)
		return true;

	return false;
}

/**
 * parse_spcr() - parse ACPI SPCR table and add preferred console
 *
 * @earlycon: set up earlycon for the console specified by the table
 *
 * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
 * defined to parse ACPI SPCR table.  As a result of the parsing preferred
 * console is registered and if @earlycon is true, earlycon is set up.
 *
 * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
 * from arch inintialization code as soon as the DT/ACPI decision is made.
 *
 */
int __init parse_spcr(bool earlycon)
{
	static char opts[64];
	struct acpi_table_spcr *table;
	acpi_status status;
	char *uart;
	char *iotype;
	int baud_rate;
	int err;

	if (acpi_disabled)
		return -ENODEV;

	status = acpi_get_table(ACPI_SIG_SPCR, 0,
				(struct acpi_table_header **)&table);

	if (ACPI_FAILURE(status))
		return -ENOENT;

	if (table->header.revision < 2) {
		err = -ENOENT;
		pr_err("wrong table version\n");
		goto done;
	}

	iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ?
			"mmio" : "io";

	switch (table->interface_type) {
	case ACPI_DBG2_ARM_SBSA_32BIT:
		iotype = "mmio32";
		/* fall through */
	case ACPI_DBG2_ARM_PL011:
	case ACPI_DBG2_ARM_SBSA_GENERIC:
	case ACPI_DBG2_BCM2835:
		uart = "pl011";
		break;
	case ACPI_DBG2_16550_COMPATIBLE:
	case ACPI_DBG2_16550_SUBSET:
		uart = "uart";
		break;
	default:
		err = -ENOENT;
		goto done;
	}

	switch (table->baud_rate) {
	case 3:
		baud_rate = 9600;
		break;
	case 4:
		baud_rate = 19200;
		break;
	case 6:
		baud_rate = 57600;
		break;
	case 7:
		baud_rate = 115200;
		break;
	default:
		err = -ENOENT;
		goto done;
	}

	/*
	 * If the E44 erratum is required, then we need to tell the pl011
	 * driver to implement the work-around.
	 *
	 * The global variable is used by the probe function when it
	 * creates the UARTs, whether or not they're used as a console.
	 *
	 * If the user specifies "traditional" earlycon, the qdf2400_e44
	 * console name matches the EARLYCON_DECLARE() statement, and
	 * SPCR is not used.  Parameter "earlycon" is false.
	 *
	 * If the user specifies "SPCR" earlycon, then we need to update
	 * the console name so that it also says "qdf2400_e44".  Parameter
	 * "earlycon" is true.
	 *
	 * For consistency, if we change the console name, then we do it
	 * for everyone, not just earlycon.
	 */
	if (qdf2400_erratum_44_present(&table->header)) {
		qdf2400_e44_present = true;
		if (earlycon)
			uart = "qdf2400_e44";
	}

	snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
		 table->serial_port.address, baud_rate);

	pr_info("console: %s\n", opts);

	if (earlycon)
		setup_earlycon(opts);

	err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);

done:
	acpi_put_table((struct acpi_table_header *)table);
	return err;
}
Commit	Line	Data
ad1696f6 AM	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
686378f9 TT	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	* parse_spcr().
	25	*/
	26	bool qdf2400_e44_present;
	27	EXPORT_SYMBOL(qdf2400_e44_present);
	28
02f469fe SH	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) &&
d0704005	43	h->oem_revision == 1)
02f469fe SH	44	return true;
	45
	46	return false;
	47	}
	48
ad1696f6 AM	49	/**
	50	* parse_spcr() - parse ACPI SPCR table and add preferred console
	51	*
	52	* @earlycon: set up earlycon for the console specified by the table
	53	*
	54	* For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
	55	* defined to parse ACPI SPCR table. As a result of the parsing preferred
	56	* console is registered and if @earlycon is true, earlycon is set up.
	57	*
	58	* When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
	59	* from arch inintialization code as soon as the DT/ACPI decision is made.
	60	*
	61	*/
	62	int __init parse_spcr(bool earlycon)
	63	{
	64	static char opts[64];
	65	struct acpi_table_spcr *table;
ad1696f6 AM	66	acpi_status status;
	67	char *uart;
	68	char *iotype;
	69	int baud_rate;
	70	int err;
	71
	72	if (acpi_disabled)
	73	return -ENODEV;
	74
6b11d1d6 LZ	75	status = acpi_get_table(ACPI_SIG_SPCR, 0,
6b11d1d6 LZ	76	(struct acpi_table_header **)&table);
ad1696f6 AM	77
	78	if (ACPI_FAILURE(status))
	79	return -ENOENT;
	80
	81	if (table->header.revision < 2) {
	82	err = -ENOENT;
	83	pr_err("wrong table version\n");
	84	goto done;
	85	}
	86
	87	iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ?
	88	"mmio" : "io";
	89
	90	switch (table->interface_type) {
	91	case ACPI_DBG2_ARM_SBSA_32BIT:
	92	iotype = "mmio32";
	93	/* fall through */
	94	case ACPI_DBG2_ARM_PL011:
	95	case ACPI_DBG2_ARM_SBSA_GENERIC:
	96	case ACPI_DBG2_BCM2835:
	97	uart = "pl011";
	98	break;
	99	case ACPI_DBG2_16550_COMPATIBLE:
	100	case ACPI_DBG2_16550_SUBSET:
	101	uart = "uart";
	102	break;
	103	default:
	104	err = -ENOENT;
	105	goto done;
	106	}
	107
	108	switch (table->baud_rate) {
	109	case 3:
	110	baud_rate = 9600;
	111	break;
	112	case 4:
	113	baud_rate = 19200;
	114	break;
	115	case 6:
	116	baud_rate = 57600;
	117	break;
	118	case 7:
	119	baud_rate = 115200;
	120	break;
	121	default:
	122	err = -ENOENT;
	123	goto done;
	124	}
	125
686378f9 TT	126	/*
	127	* If the E44 erratum is required, then we need to tell the pl011
	128	* driver to implement the work-around.
	129	*
	130	* The global variable is used by the probe function when it
	131	* creates the UARTs, whether or not they're used as a console.
	132	*
	133	* If the user specifies "traditional" earlycon, the qdf2400_e44
	134	* console name matches the EARLYCON_DECLARE() statement, and
	135	* SPCR is not used. Parameter "earlycon" is false.
	136	*
	137	* If the user specifies "SPCR" earlycon, then we need to update
	138	* the console name so that it also says "qdf2400_e44". Parameter
	139	* "earlycon" is true.
	140	*
	141	* For consistency, if we change the console name, then we do it
	142	* for everyone, not just earlycon.
	143	*/
	144	if (qdf2400_erratum_44_present(&table->header)) {
	145	qdf2400_e44_present = true;
	146	if (earlycon)
	147	uart = "qdf2400_e44";
	148	}
02f469fe	149
ad1696f6 AM	150	snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
	151	table->serial_port.address, baud_rate);
	152
	153	pr_info("console: %s\n", opts);
	154
	155	if (earlycon)
	156	setup_earlycon(opts);
	157
	158	err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
	159
	160	done:
6b11d1d6	161	acpi_put_table((struct acpi_table_header *)table);
ad1696f6 AM	162	return err;
ad1696f6 AM	163	}