[PATCH v3 05/10] serial: 8250: dw: Allow to use a fallback CPR value if not synthesized

[Miquel Raynal <miquel.raynal@bootlin.com>]

DW UART controllers can be synthesized without the CPR register.
In this case, allow to the platform information to provide a CPR value.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Co-developed-by: Miquel Raynal <miquel.raynal@bootlin.com>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
---
 drivers/tty/serial/8250/8250_dwlib.c | 9 +++++++++
 drivers/tty/serial/8250/8250_dwlib.h | 1 +
 2 files changed, 10 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_dwlib.c b/drivers/tty/serial/8250/8250_dwlib.c
index 622d3b0d89e7..6c4fe1792eb5 100644
--- a/drivers/tty/serial/8250/8250_dwlib.c
+++ b/drivers/tty/serial/8250/8250_dwlib.c
@@ -5,6 +5,7 @@
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/kernel.h>
+#include <linux/property.h>
 #include <linux/serial_8250.h>
 #include <linux/serial_core.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 *pdata = device_get_match_data(p->dev);
 	u32 reg;
 
 	/*
@@ -116,6 +118,13 @@ void dw8250_setup_port(struct uart_port *p)
 	}
 
 	reg = dw8250_readl_ext(p, DW_UART_CPR);
+	if (!reg) {
+		if (pdata)
+			reg = pdata->cpr;
+
+		dev_dbg(p->dev, "CPR is not available, using %x instead\n", reg);
+	}
+
 	if (!reg)
 		return;
 
diff --git a/drivers/tty/serial/8250/8250_dwlib.h b/drivers/tty/serial/8250/8250_dwlib.h
index 7dfc2d6361e5..19c530b7fd1d 100644
--- a/drivers/tty/serial/8250/8250_dwlib.h
+++ b/drivers/tty/serial/8250/8250_dwlib.h
@@ -23,6 +23,7 @@ struct dw8250_port_data {
 
 struct dw8250_platform_data {
 	unsigned int quirks;
+	u32 cpr;
 };
 
 struct dw8250_data {
-- 
2.27.0