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]> --- drivers/acpi/spcr.c | 22 ++++++++++++++++++++++ drivers/tty/serial/amba-pl011.c | 2 ++ include/linux/acpi.h | 5 +++++ 3 files changed, 29 insertions(+) diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c index c460cb1..f2e81af 100644 --- a/drivers/acpi/spcr.c +++ b/drivers/acpi/spcr.c @@ -18,6 +18,7 @@ static char *options; static struct acpi_generic_address address; +static bool sbsa_32_bit; static int __init parse_spcr_init(void) { @@ -60,6 +61,7 @@ static int __init parse_spcr_init(void) } address = table->serial_port; + sbsa_32_bit = table->interface_type == ACPI_DBG2_ARM_SBSA_32BIT; done: early_acpi_os_unmap_memory((void __iomem *)table, table_size); @@ -114,3 +116,23 @@ bool acpi_console_check(struct uart_port *uport) return false; } + +/** + * 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 || parse_spcr() < 0) + return false; + + return sbsa_32_bit; +} +EXPORT_SYMBOL(acpi_console_sbsa_32bit); diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c index 500232a..d9ca3a4 100644 --- a/drivers/tty/serial/amba-pl011.c +++ b/drivers/tty/serial/amba-pl011.c @@ -2541,6 +2541,8 @@ 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/acpi.h b/include/linux/acpi.h index ea0c297..da1eb23 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -1007,11 +1007,16 @@ static inline struct fwnode_handle *acpi_get_next_subnode(struct device *dev, struct uart_port; #ifdef CONFIG_ACPI_SPCR_TABLE bool acpi_console_check(struct uart_port *uport); +bool acpi_console_sbsa_32bit(void); #else static inline bool acpi_console_check(struct uart_port *uport) { return FALSE; } +static inline bool acpi_console_sbsa_32bit(void) +{ + return false; +} #endif #endif /*_LINUX_ACPI_H*/ -- 2.7.1
