Some implementations of ARM SBSA serial port hardware require that access to the registers should be 32-bit. Unfortunately, the only way for the driver to tell if it's the case is to use the data from ACPI SPCR/DBG2 tables. In this case the value of the 'Interface Type' field of the SPCR table is ACPI_DBG2_ARM_SBSA_32BIT.
How this value is described in the DBG2 spec: "(deprecated) ARM SBSA (2.x only) Generic UART supporting only 32-bit accesses" Signed-off-by: Aleksey Makarov <[email protected]> Tested-by: Christopher Covington <[email protected]> --- drivers/acpi/spcr.c | 29 +++++++++++++++++++++++++++++ drivers/tty/serial/amba-pl011.c | 2 ++ include/linux/console.h | 5 +++++ 3 files changed, 36 insertions(+) diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c index 0475840..df1741f 100644 --- a/drivers/acpi/spcr.c +++ b/drivers/acpi/spcr.c @@ -75,3 +75,32 @@ int acpi_console_match(struct console *console, char **options) return acpi_table_parse2(ACPI_SIG_SPCR, spcr_table_handler_match, &d); } + +static int spcr_table_handler_32_bit(struct acpi_table_header *t, + void *data) +{ + struct acpi_table_spcr *table = (struct acpi_table_spcr *)t; + + return table->interface_type == ACPI_DBG2_ARM_SBSA_32BIT; +} + +/** + * acpi_console_sbsa_32bit - Tell if SPCR specifies 32-bit SBSA. + * + * Some implementations of ARM SBSA serial port hardware require that access + * to the registers should be 32-bit. Unfortunately, the only way for + * the driver to tell if it's the case is to use the data from ACPI SPCR/DBG2 + * tables. In this case the value of the 'Interface Type' field of the SPCR + * table is ACPI_DBG2_ARM_SBSA_32BIT. + * + * Return: true if access should be 32-bit wide. + */ +bool acpi_console_sbsa_32bit(void) +{ + if (acpi_disabled) + return false; + + return acpi_table_parse2(ACPI_SIG_SPCR, + spcr_table_handler_32_bit, NULL) > 0; +} +EXPORT_SYMBOL(acpi_console_sbsa_32bit); diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index f613bff..699a3ce 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -2563,6 +2563,8 @@ static int sbsa_uart_probe(struct platform_device *pdev) baudrate = 115200; } + vendor_sbsa.access_32b = acpi_console_sbsa_32bit(); + portnr = pl011_find_free_port(); if (portnr < 0) return portnr; diff --git a/include/linux/console.h b/include/linux/console.h index dcc2b59..027ef50 100644 --- a/include/linux/console.h +++ b/include/linux/console.h @@ -137,11 +137,16 @@ struct console { #ifdef CONFIG_ACPI_SPCR_TABLE int acpi_console_match(struct console *c, char **options); +bool acpi_console_sbsa_32bit(void); #else static inline int acpi_console_match(struct console *c, char **options) { return -ENODEV; } +static inline bool acpi_console_sbsa_32bit(void) +{ + return false; +} #endif /* -- 2.7.0
