[PATCH 3/7] serial: 8250_dw: Use a fallback CPR value if not synthesized

[Miquel Raynal <miquel.raynal@xxxxxxxxxxx>]

From: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>

This UART controller can be synthesized without the CPR register.
In that case, let's use the platform information to provide a CPR value.

Signed-off-by: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_dwlib.c | 10 ++++++++--
 drivers/tty/serial/8250/8250_dwlib.h |  4 ++++
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_dwlib.c b/drivers/tty/serial/8250/8250_dwlib.c
index 622d3b0d89e7..5cf298c5a0f9 100644
--- a/drivers/tty/serial/8250/8250_dwlib.c
+++ b/drivers/tty/serial/8250/8250_dwlib.c
@@ -3,6 +3,7 @@
 
 #include <linux/bitops.h>
 #include <linux/device.h>
+#include <linux/of_device.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
 #include <linux/serial_8250.h>
@@ -90,6 +91,7 @@ EXPORT_SYMBOL_GPL(dw8250_do_set_termios);
 void dw8250_setup_port(struct uart_port *p)
 {
 	struct uart_8250_port *up = up_to_u8250p(p);
+	const struct dw8250_platform_data *plat = of_device_get_match_data(up->port.dev);
 	u32 reg;
 
 	/*
@@ -116,8 +118,12 @@ void dw8250_setup_port(struct uart_port *p)
 	}
 
 	reg = dw8250_readl_ext(p, DW_UART_CPR);
-	if (!reg)
-		return;
+	if (!reg) {
+		if (!plat)
+			return;
+
+		reg = plat->cpr;
+	}
 
 	/* Select the type based on FIFO */
 	if (reg & DW_UART_CPR_FIFO_MODE) {
diff --git a/drivers/tty/serial/8250/8250_dwlib.h b/drivers/tty/serial/8250/8250_dwlib.h
index ef63eaf7e598..ffce2744a28e 100644
--- a/drivers/tty/serial/8250/8250_dwlib.h
+++ b/drivers/tty/serial/8250/8250_dwlib.h
@@ -16,6 +16,10 @@ struct dw8250_port_data {
 	u8			dlf_size;
 };
 
+struct dw8250_platform_data {
+	u32 cpr;
+};
+
 struct dw8250_data {
 	struct dw8250_port_data	data;
 
-- 
2.27.0