From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
There is no way to access a struct uart_8250_port for a specific
line. This is only required outside of the 8250/uart callbacks like for
devices' suspend & remove callbacks. For those the 8250-core provides a
wrapper like serial8250_unregister_port() which passes the struct
to the proper function based on the line argument.
For run time suspend I need access to this struct not only to make
serial_out() work but also to properly restore up->ier and up->mcr.
Acked-by: Alan Cox <alan@xxxxxxxxxxxxxxx>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
(cherry picked from commit ae14a7954f5124208e6e93cafb3099f83acd43f5)
Signed-off-by: Chang Rebecca Swee Fun <rebecca.swee.fun.chang@xxxxxxxxx>
---
drivers/tty/serial/8250/8250.h | 2 ++
drivers/tty/serial/8250/8250_core.c | 18 ++++++++++++++++++
2 files changed, 20 insertions(+)
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 1b08c91..85bfec5 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -112,6 +112,8 @@ static inline void serial_dl_write(struct uart_8250_port *up, int value)
up->dl_write(up, value);
}
+struct uart_8250_port *serial8250_get_port(int line);
+
#if defined(__alpha__) && !defined(CONFIG_PCI)
/*
* Digital did something really horribly wrong with the OUT1 and OUT2
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index e7a8517..9eae028 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -2879,6 +2879,24 @@ static struct uart_ops serial8250_pops = {
static struct uart_8250_port serial8250_ports[UART_NR];
+/**
+ * serial8250_get_port - retrieve struct uart_8250_port
+ * @line: serial line number
+ *
+ * This function retrieves struct uart_8250_port for the specific line.
+ * This struct *must* *not* be used to perform a 8250 or serial core operation
+ * which is not accessible otherwise. Its only purpose is to make the struct
+ * accessible to the runtime-pm callbacks for context suspend/restore.
+ * The lock assumption made here is none because runtime-pm suspend/resume
+ * callbacks should not be invoked if there is any operation performed on the
+ * port.
+ */
+struct uart_8250_port *serial8250_get_port(int line)
+{
+ return &serial8250_ports[line];
+}
+EXPORT_SYMBOL_GPL(serial8250_get_port);
+
static void (*serial8250_isa_config)(int port, struct uart_port *up,
unsigned short *capabilities);
--
1.7.9.5
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