[U-Boot] [PATCH v6 5/9] arm: serial: Add ability to use pre-initialized UARTs

[Sergey Temerkhanov]

On some systems, UART initialization is performed before running U-Boot.
This commit allows to skip UART re-initializaion on those systems

Signed-off-by: Sergey Temerkhanov <s.temerkhanov at gmail.com>
Signed-off-by: Radha Mohan Chintakuntla <rchintakuntla at cavium.com>

Reviewed-by: Simon Glass <sjg at chromium.org>

---

Changes in v6:
- Changed the 'PL0X_PREINITIALIZED' flag to the 'skip-init' bool

Changes in v5:
- Added OF control support

Changes in v4:
- Fixed build warnings
- Moved to DM_SERIAL

Changes in v3:
- Added __used keyword

Changes in v2: None

 doc/device-tree-bindings/serial/pl01x.txt |  3 +++
 drivers/serial/serial_pl01x.c             | 14 ++++++++------
 include/dm/platform_data/serial_pl01x.h   |  2 ++
 3 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/doc/device-tree-bindings/serial/pl01x.txt b/doc/device-tree-bindings/serial/pl01x.txt
index 61c27d1..0591497 100644
--- a/doc/device-tree-bindings/serial/pl01x.txt
+++ b/doc/device-tree-bindings/serial/pl01x.txt
@@ -5,3 +5,6 @@ Required properties:
 - reg: exactly one register range with length 0x1000
 - clock: input clock frequency for the UART (used to calculate the baud
   rate divisor)
+
+Optional properties:
+- u-boot,skip-init: skip UART initialization at start.
diff --git a/drivers/serial/serial_pl01x.c b/drivers/serial/serial_pl01x.c
index 3a5c1d0..de9f642 100644
--- a/drivers/serial/serial_pl01x.c
+++ b/drivers/serial/serial_pl01x.c
@@ -103,7 +103,7 @@ static int pl011_set_line_control(struct pl01x_regs *regs)
 }
 
 static int pl01x_generic_setbrg(struct pl01x_regs *regs, enum pl01x_type type,
-				int clock, int baudrate)
+				       int clock, int baudrate)
 {
 	switch (type) {
 	case TYPE_PL010: {
@@ -273,7 +273,6 @@ __weak struct serial_device *default_serial_console(void)
 #endif /* nCONFIG_DM_SERIAL */
 
 #ifdef CONFIG_DM_SERIAL
-
 struct pl01x_priv {
 	struct pl01x_regs *regs;
 	enum pl01x_type type;
@@ -284,9 +283,9 @@ static int pl01x_serial_setbrg(struct udevice *dev, int baudrate)
 	struct pl01x_serial_platdata *plat = dev_get_platdata(dev);
 	struct pl01x_priv *priv = dev_get_priv(dev);
 
-	pl01x_generic_setbrg(priv->regs, priv->type, plat->clock, baudrate);
-
-	return 0;
+	return plat->skip_init ? 0 :
+		pl01x_generic_setbrg(priv->regs, priv->type,
+				     plat->clock, baudrate);
 }
 
 static int pl01x_serial_probe(struct udevice *dev)
@@ -296,7 +295,8 @@ static int pl01x_serial_probe(struct udevice *dev)
 
 	priv->regs = (struct pl01x_regs *)plat->base;
 	priv->type = plat->type;
-	return pl01x_generic_serial_init(priv->regs, priv->type);
+	return plat->skip_init ? 0 :
+		pl01x_generic_serial_init(priv->regs, priv->type);
 }
 
 static int pl01x_serial_getc(struct udevice *dev)
@@ -350,6 +350,8 @@ static int pl01x_serial_ofdata_to_platdata(struct udevice *dev)
 	plat->base = addr;
 	plat->clock = fdtdec_get_int(gd->fdt_blob, dev->of_offset, "clock", 1);
 	plat->type = dev_get_driver_data(dev);
+	plat->skip_init = fdtdec_get_bool(gd->fdt_blob, dev->of_offset,
+					  "uboot,skip-init");
 	return 0;
 }
 #endif
diff --git a/include/dm/platform_data/serial_pl01x.h b/include/dm/platform_data/serial_pl01x.h
index 5e068f3..10e9572 100644
--- a/include/dm/platform_data/serial_pl01x.h
+++ b/include/dm/platform_data/serial_pl01x.h
@@ -17,11 +17,13 @@ enum pl01x_type {
  * @base: Register base address
  * @type: Port type
  * @clock: Input clock rate, used for calculating the baud rate divisor
+ * @flags: Port flags
  */
 struct pl01x_serial_platdata {
 	unsigned long base;
 	enum pl01x_type type;
 	unsigned int clock;
+	bool skip_init;
 };
 
 #endif
-- 
2.2.0