ACPI: parse SPCR and enable matching console
'ARM Server Base Boot Requiremets' [1] mentions SPCR (Serial Port
Console Redirection Table) [2] as a mandatory ACPI table that
specifies the configuration of serial console.
Defer initialization of DT earlycon until ACPI/DT decision is made.
Parse the ACPI SPCR table, setup earlycon if required,
enable specified console.
Thanks to Peter Hurley for explaining how this should work.
[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0044a/index.html
[2] https://msdn.microsoft.com/en-us/library/windows/hardware/dn639132(v=vs.85).aspx
Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/acpi.h b/include/linux/acpi.h
index c5eaf2f..2353827 100644
--- a/include/linux/acpi.h
+++ b/include/linux/acpi.h
@@ -1074,4 +1074,10 @@
static inline void acpi_table_upgrade(void) { }
#endif
+#ifdef CONFIG_ACPI_SPCR_TABLE
+int parse_spcr(bool earlycon);
+#else
+static inline int parse_spcr(bool earlycon) { return 0; }
+#endif
+
#endif /*_LINUX_ACPI_H*/
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 378d80a..3442014 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -367,11 +367,18 @@
#define EARLYCON_DECLARE(_name, fn) OF_EARLYCON_DECLARE(_name, "", fn)
-extern int setup_earlycon(char *buf);
extern int of_setup_earlycon(const struct earlycon_id *match,
unsigned long node,
const char *options);
+#ifdef CONFIG_SERIAL_EARLYCON
+extern bool earlycon_init_is_deferred __initdata;
+int setup_earlycon(char *buf);
+#else
+static const bool earlycon_init_is_deferred;
+static inline int setup_earlycon(char *buf) { return 0; }
+#endif
+
struct uart_port *uart_get_console(struct uart_port *ports, int nr,
struct console *c);
int uart_parse_earlycon(char *p, unsigned char *iotype, resource_size_t *addr,