[PATCH v3 5/5] serial: pl011: use SPCR to setup 32-bit access
From: Aleksey Makarov <hidden>
Date: 2016-02-15 18:11:34
Also in:
linux-acpi, linux-serial, lkml
Subsystem:
acpi, arm primecell uart pl010 and pl011 drivers, the rest, tty layer and serial drivers · Maintainers:
"Rafael J. Wysocki", Russell King, Linus Torvalds, Greg Kroah-Hartman, Jiri Slaby
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 <redacted> --- drivers/acpi/spcr.c | 25 +++++++++++++++++++++++++ drivers/tty/serial/amba-pl011.c | 2 ++ include/linux/acpi.h | 5 +++++ 3 files changed, 32 insertions(+)
diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
index a1eca91..a5e241d 100644
--- a/drivers/acpi/spcr.c
+++ b/drivers/acpi/spcr.c@@ -95,3 +95,28 @@ bool acpi_console_check(struct uart_port *uport) return acpi_table_parse_spcr(spcr_table_handler_check, uport) > 0; } + +static int spcr_table_handler_32_bit(struct acpi_table_spcr *table, void *data) +{ + 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_parse_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 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