[PATCH v6 04/12] serial: 8250: dw: Allow to use a fallback CPR value if not synthesized

[Miquel Raynal <miquel.raynal@xxxxxxxxxxx>]

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

Co-developed-by: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
Signed-off-by: Phil Edworthy <phil.edworthy@xxxxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_dwlib.c | 10 +++++++---
 drivers/tty/serial/8250/8250_dwlib.h |  1 +
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_dwlib.c b/drivers/tty/serial/8250/8250_dwlib.c
index 622d3b0d89e7..f1fb20353612 100644
--- a/drivers/tty/serial/8250/8250_dwlib.c
+++ b/drivers/tty/serial/8250/8250_dwlib.c
@@ -89,6 +89,8 @@ EXPORT_SYMBOL_GPL(dw8250_do_set_termios);
 
 void dw8250_setup_port(struct uart_port *p)
 {
+	struct dw8250_port_data *pd = p->private_data;
+	struct dw8250_data *data = to_dw8250_data(pd);
 	struct uart_8250_port *up = up_to_u8250p(p);
 	u32 reg;
 
@@ -108,14 +110,16 @@ void dw8250_setup_port(struct uart_port *p)
 	dw8250_writel_ext(p, DW_UART_DLF, 0);
 
 	if (reg) {
-		struct dw8250_port_data *d = p->private_data;
-
-		d->dlf_size = fls(reg);
+		pd->dlf_size = fls(reg);
 		p->get_divisor = dw8250_get_divisor;
 		p->set_divisor = dw8250_set_divisor;
 	}
 
 	reg = dw8250_readl_ext(p, DW_UART_CPR);
+	if (!reg) {
+		reg = data->pdata->cpr_val;
+		dev_dbg(p->dev, "CPR is not available, using 0x%08x 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 0df6baa6eaee..36a839ef5d9a 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 {
 	u8 usr_reg;
+	u32 cpr_val;
 	unsigned int quirks;
 };
 
-- 
2.27.0