[PATCH 1/6] tty: serial: 8250 core: provide a function to export uart_8250_port

From: Sebastian Andrzej Siewior
Date: Wed Jul 09 2014 - 13:51:58 EST

There is no access 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
wrapper like serial8250_unregister_port() which passes the struct
to the proper function based on the line argument.

For runtime suspend I need access to this struct not only to make
serial_out() work but also to properly restore up->ier and up->mcr.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
drivers/tty/serial/8250/8250.h | 2 ++
drivers/tty/serial/8250/8250_core.c | 17 +++++++++++++++++
2 files changed, 19 insertions(+)

diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 1ebf853..34c3cd1 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -110,6 +110,8 @@ 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 7a91c6d..6db2ee2 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -2755,6 +2755,23 @@ 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 there is any operation performed on the port.
+ */
+struct uart_8250_port *serial8250_get_port(int line)
+ return &serial8250_ports[line];
static void (*serial8250_isa_config)(int port, struct uart_port *up,
unsigned short *capabilities);


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