serial: samsung: get fifosize via device tree

UART modules on some SoCs only differ in the fifosize of each
UART channel. Its useless to duplicate the drv_data structure
or create a compatible name for such a change.

We can get fifosize via the device tree nodes (not mandating it).

Also updates the documentation.

Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
Reviewed-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 13 insertions, 3 deletions

diff --git a/Documentation/devicetree/bindings/serial/samsung_uart.txt b/Documentation/devicetree/bindings/serial/samsung_uart.txt
index 85e8ee2a17fc..e85f37ec33f0 100644
--- a/Documentation/devicetree/bindings/serial/samsung_uart.txt
+++ b/Documentation/devicetree/bindings/serial/samsung_uart.txt
@@ -29,6 +29,9 @@ Required properties:
 [1] Documentation/devicetree/bindings/interrupt-controller/interrupts.txt
 [2] Documentation/devicetree/bindings/clock/clock-bindings.txt
 
+Optional properties:
+- samsung,uart-fifosize: The fifo size supported by the UART channel
+
 Note: Each Samsung UART should have an alias correctly numbered in the
 "aliases" node, according to serialN format, where N is the port number
 (non-negative decimal integer) as specified by User's Manual of respective
@@ -51,4 +54,5 @@ Example:
                                 "clk_uart_baud3";
                 clocks = <&clocks PCLK_UART1>, <&clocks PCLK_UART1>,
                                 <&clocks SCLK_UART>;
+                samsung,uart-fifosize = <16>;
         };
diff --git a/drivers/tty/serial/samsung.c b/drivers/tty/serial/samsung.c
index 6be852d4df6d..e49a9451976e 100644
--- a/drivers/tty/serial/samsung.c
+++ b/drivers/tty/serial/samsung.c
@@ -1295,9 +1295,15 @@ static int s3c24xx_serial_probe(struct platform_device *pdev)
                         dev_get_platdata(&pdev->dev) :
                         ourport->drv_data->def_cfg;
 
-        ourport->port.fifosize = (ourport->info->fifosize) ?
-                ourport->info->fifosize :
-                ourport->drv_data->fifosize[index];
+        if (pdev->dev.of_node)
+                of_property_read_u32(pdev->dev.of_node,
+                        "samsung,uart-fifosize", &ourport->port.fifosize);
+
+        if (!ourport->port.fifosize) {
+                ourport->port.fifosize = (ourport->info->fifosize) ?
+                        ourport->info->fifosize :
+                        ourport->drv_data->fifosize[index];
+        }
 
         probe_index++;