[PATCH 0/6] Raspberry Pi miniuart support

[PATCH 0/6] Raspberry Pi miniuart support

[Rouven Czerwinski]

This patch series adds support for the raspberry pi miniuart (also called
aux-uart) to barebox.
With this series the miniuart overlay is no longer necessary to start barebox on
Raspberry Pi 3.

Rouven Czerwinski (6):
  mach-bcm2835/core: add clkdev for uart1
  serial_ns16550: handle default reg-io-width
  serial_ns16550: add raspberry pi compatible and init
  ARM: rpi: add NS16550 support
  bcm2837-rpi-3: choose miniuart as stdout
  doc: bcm283x: remove miniuart overlay instruction

 Documentation/boards/bcm2835.rst |  1 -
 arch/arm/configs/rpi_defconfig   |  1 +
 arch/arm/dts/bcm2837-rpi-3.dts   |  7 +----
 arch/arm/mach-bcm283x/core.c     |  6 ++++
 drivers/serial/serial_ns16550.c  | 66 ++++++++++++++++++++++++++--------------
 5 files changed, 51 insertions(+), 30 deletions(-)

-- 
2.11.0


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[PATCH 1/6] mach-bcm2835/core: add clkdev for uart1

[Rouven Czerwinski]

Add a clkdev for uart1 which will be used on the Raspberry Pi 3.
Double the clockrate since the ns16550 driver used for the uart will divide by
16, while the bcm2835 peripheral manual describes that the bcm2835 miniuart will
only divide by 8.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
---
 arch/arm/mach-bcm283x/core.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/mach-bcm283x/core.c b/arch/arm/mach-bcm283x/core.c
index f1dcda86f..66af76b09 100644
--- a/arch/arm/mach-bcm283x/core.c
+++ b/arch/arm/mach-bcm283x/core.c
@@ -42,6 +42,12 @@ static int bcm2835_clk_init(void)
 	clk_register_clkdev(clk, NULL, "uart0-pl0110");
 	clkdev_add_physbase(clk, 0x20201000, NULL);
 	clkdev_add_physbase(clk, 0x3f201000, NULL);
+	/*
+	 * We double the clock rate since the 16550 will divide by 16
+	 * (instead of 8 required by the BCM2835 peripheral manual)
+	 */
+	clk = clk_fixed("uart1-8250", 500 * 1000 * 1000);
+	clkdev_add_physbase(clk, 0x3f215040, NULL);
 
 	clk = clk_fixed("bcm2835-cs", 1 * 1000 * 1000);
 	clk_register_clkdev(clk, NULL, "bcm2835-cs");
-- 
2.11.0


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[PATCH 2/6] serial_ns16550: handle default reg-io-width

[Rouven Czerwinski]

According to the device tree bindings for 8250, width is an optional property.
Default to 1 which is the same default value as used by the kernel.
Before this change the driver would not work for device trees which do not
include the optional binding.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
---
 drivers/serial/serial_ns16550.c | 46 ++++++++++++++++++++---------------------
 1 file changed, 23 insertions(+), 23 deletions(-)

diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c
index 4d73ea8b8..8ddcfdbef 100644
--- a/drivers/serial/serial_ns16550.c
+++ b/drivers/serial/serial_ns16550.c
@@ -297,36 +297,36 @@ static int ns16550_tstc(struct console_device *cdev)
 static void ns16550_probe_dt(struct device_d *dev, struct ns16550_priv *priv)
 {
 	struct device_node *np = dev->device_node;
-	u32 width;
+	u32 width = 1;
 
 	if (!IS_ENABLED(CONFIG_OFDEVICE))
 		return;
 
 	of_property_read_u32(np, "clock-frequency", &priv->plat.clock);
 	of_property_read_u32(np, "reg-shift", &priv->plat.shift);
-	if (!of_property_read_u32(np, "reg-io-width", &width))
-		switch (width) {
-		case 1:
-			priv->read_reg = ns16550_read_reg_mmio_8;
-			priv->write_reg = ns16550_write_reg_mmio_8;
-			break;
-		case 2:
-			priv->read_reg = ns16550_read_reg_mmio_16;
-			priv->write_reg = ns16550_write_reg_mmio_16;
-			break;
-		case 4:
-			if (of_device_is_big_endian(np)) {
-				priv->read_reg = ns16550_read_reg_mmio_32be;
-				priv->write_reg = ns16550_write_reg_mmio_32be;
-			} else {
-				priv->read_reg = ns16550_read_reg_mmio_32;
-				priv->write_reg = ns16550_write_reg_mmio_32;
-			}
-			break;
-		default:
-			dev_err(dev, "unsupported reg-io-width (%d)\n",
-				width);
+	of_property_read_u32(np, "reg-io-width", &width);
+	switch (width) {
+	case 1:
+		priv->read_reg = ns16550_read_reg_mmio_8;
+		priv->write_reg = ns16550_write_reg_mmio_8;
+		break;
+	case 2:
+		priv->read_reg = ns16550_read_reg_mmio_16;
+		priv->write_reg = ns16550_write_reg_mmio_16;
+		break;
+	case 4:
+		if (of_device_is_big_endian(np)) {
+			priv->read_reg = ns16550_read_reg_mmio_32be;
+			priv->write_reg = ns16550_write_reg_mmio_32be;
+		} else {
+			priv->read_reg = ns16550_read_reg_mmio_32;
+			priv->write_reg = ns16550_write_reg_mmio_32;
 		}
+		break;
+	default:
+		dev_err(dev, "unsupported reg-io-width (%d)\n",
+			width);
+	}
 }
 
 static struct ns16550_drvdata ns16450_drvdata = {
-- 
2.11.0


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[PATCH 3/6] serial_ns16550: add raspberry pi compatible and init

[Rouven Czerwinski]

Add the compatible for the Raspberry Pi AUX UART and an init function which
enables it via the aux register and configures the correct shift value.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
---
 drivers/serial/serial_ns16550.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c
index 8ddcfdbef..e872fb886 100644
--- a/drivers/serial/serial_ns16550.c
+++ b/drivers/serial/serial_ns16550.c
@@ -253,6 +253,15 @@ static void ns16550_jz_init_port(struct console_device *cdev)
 	ns16550_serial_init_port(cdev);
 }
 
+static void rpi_init_port(struct console_device *cdev)
+{
+  struct ns16550_priv *priv = to_ns16550_priv(cdev);
+
+  writeb(0x01, 0x3f215004);
+  priv->plat.shift = 2;
+  ns16550_serial_init_port(cdev);
+}
+
 /*********** Exposed Functions **********************************/
 
 /**
@@ -353,6 +362,11 @@ static __maybe_unused struct ns16550_drvdata tegra_drvdata = {
 	.linux_console_name = "ttyS",
 };
 
+static struct ns16550_drvdata rpi_drvdata = {
+  .init_port = rpi_init_port,
+  .linux_console_name = "ttyS",
+};
+
 static int ns16550_init_iomem(struct device_d *dev, struct ns16550_priv *priv)
 {
 	struct resource *iores;
@@ -528,6 +542,12 @@ static struct of_device_id ns16550_serial_dt_ids[] = {
 		.data = &jz_drvdata,
 	},
 #endif
+#if IS_ENABLED(CONFIG_MACH_RPI_COMMON)
+	{
+	  .compatible = "brcm,bcm2835-aux-uart",
+	  .data = &rpi_drvdata,
+	},
+#endif
 	{
 		/* sentinel */
 	},
-- 
2.11.0


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[PATCH 4/6] ARM: rpi: add NS16550 support

[Rouven Czerwinski]

Since the 16550 driver now supports the RPI3 miniuart, enable it in the default
config.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
---
 arch/arm/configs/rpi_defconfig | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm/configs/rpi_defconfig b/arch/arm/configs/rpi_defconfig
index 2bb615849..dc5ab1fe1 100644
--- a/arch/arm/configs/rpi_defconfig
+++ b/arch/arm/configs/rpi_defconfig
@@ -63,6 +63,7 @@ CONFIG_CMD_OF_PROPERTY=y
 CONFIG_CMD_OFTREE=y
 CONFIG_CMD_TIME=y
 CONFIG_SERIAL_AMBA_PL011=y
+CONFIG_DRIVER_SERIAL_NS16550=y
 CONFIG_MCI=y
 CONFIG_MCI_BCM283X=y
 CONFIG_LED=y
-- 
2.11.0


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[PATCH 5/6] bcm2837-rpi-3: choose miniuart as stdout

[Rouven Czerwinski]

Since we now support the miniuart, enable it as the default stdout port.
With this change the device tree overlay to switch the miniuart to bluetooth is
no longer necessary.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
---
 arch/arm/dts/bcm2837-rpi-3.dts | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/arch/arm/dts/bcm2837-rpi-3.dts b/arch/arm/dts/bcm2837-rpi-3.dts
index d6ffc3691..194b41c23 100644
--- a/arch/arm/dts/bcm2837-rpi-3.dts
+++ b/arch/arm/dts/bcm2837-rpi-3.dts
@@ -2,15 +2,10 @@
 
 / {
 	chosen {
-		stdout-path = &uart0;
+		stdout-path = &uart1;
 	};
 
 	memory {
 		reg = <0x0 0x0>;
 	};
 };
-
-&uart0 {
-	status = "okay";
-	/delete-node/ bluetooth;
-};
-- 
2.11.0


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[PATCH 6/6] doc: bcm283x: remove miniuart overlay instruction

[Rouven Czerwinski]

Since we now use the miniuart on the raspberry pi 3, the miniuart overlay is no
longer needed.

Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
---
 Documentation/boards/bcm2835.rst | 1 -
 1 file changed, 1 deletion(-)

diff --git a/Documentation/boards/bcm2835.rst b/Documentation/boards/bcm2835.rst
index 79ea0ff7a..ea80d5834 100644
--- a/Documentation/boards/bcm2835.rst
+++ b/Documentation/boards/bcm2835.rst
@@ -22,7 +22,6 @@ Raspberry Pi
 
          kernel=barebox.img
          enable_uart=1
-         dtoverlay=pi3-miniuart-bt
 
      (For more information, refer to the `documentation for config.txt`_.)
 
-- 
2.11.0


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Re: [PATCH 1/6] mach-bcm2835/core: add clkdev for uart1

[Lucas Stach]

Am Mittwoch, den 12.12.2018, 15:10 +0100 schrieb Rouven Czerwinski:
> Add a clkdev for uart1 which will be used on the Raspberry Pi 3.
> Double the clockrate since the ns16550 driver used for the uart will divide by
> 16, while the bcm2835 peripheral manual describes that the bcm2835 miniuart will
> only divide by 8.
> 
> > Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
> ---
>  arch/arm/mach-bcm283x/core.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/arm/mach-bcm283x/core.c b/arch/arm/mach-bcm283x/core.c
> index f1dcda86f..66af76b09 100644
> --- a/arch/arm/mach-bcm283x/core.c
> +++ b/arch/arm/mach-bcm283x/core.c
> @@ -42,6 +42,12 @@ static int bcm2835_clk_init(void)
> >  	clk_register_clkdev(clk, NULL, "uart0-pl0110");
> >  	clkdev_add_physbase(clk, 0x20201000, NULL);
> >  	clkdev_add_physbase(clk, 0x3f201000, NULL);
> > +	/*
> > +	 * We double the clock rate since the 16550 will divide by 16
> > +	 * (instead of 8 required by the BCM2835 peripheral manual)
> +	 */

This is confusing. The clock is running at another rate. I would prefer
to do this adjustment in rpi_init_port() in the ns16550 driver, as
that's the point where the hardware deviation actually is.

Regards,
Lucas

> +	clk = clk_fixed("uart1-8250", 500 * 1000 * 1000);
> > +	clkdev_add_physbase(clk, 0x3f215040, NULL);
>  
> >  	clk = clk_fixed("bcm2835-cs", 1 * 1000 * 1000);
> >  	clk_register_clkdev(clk, NULL, "bcm2835-cs");

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Re: [PATCH 1/6] mach-bcm2835/core: add clkdev for uart1

[Rouven Czerwinski]

On Wed, 2018-12-12 at 15:22 +0100, Lucas Stach wrote:
> Am Mittwoch, den 12.12.2018, 15:10 +0100 schrieb Rouven Czerwinski:
> > Add a clkdev for uart1 which will be used on the Raspberry Pi 3.
> > Double the clockrate since the ns16550 driver used for the uart
> > will divide by
> > 16, while the bcm2835 peripheral manual describes that the bcm2835
> > miniuart will
> > only divide by 8.
> > 
> > > Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
> > 
> > ---
> >  arch/arm/mach-bcm283x/core.c | 6 ++++++
> >  1 file changed, 6 insertions(+)
> > 
> > diff --git a/arch/arm/mach-bcm283x/core.c b/arch/arm/mach-
> > bcm283x/core.c
> > index f1dcda86f..66af76b09 100644
> > --- a/arch/arm/mach-bcm283x/core.c
> > +++ b/arch/arm/mach-bcm283x/core.c
> > @@ -42,6 +42,12 @@ static int bcm2835_clk_init(void)
> > >  	clk_register_clkdev(clk, NULL, "uart0-pl0110");
> > >  	clkdev_add_physbase(clk, 0x20201000, NULL);
> > >  	clkdev_add_physbase(clk, 0x3f201000, NULL);
> > > +	/*
> > > +	 * We double the clock rate since the 16550 will divide
> > > by 16
> > > +	 * (instead of 8 required by the BCM2835 peripheral
> > > manual)
> > 
> > +	 */
> 
> This is confusing. The clock is running at another rate. I would
> prefer
> to do this adjustment in rpi_init_port() in the ns16550 driver, as
> that's the point where the hardware deviation actually is.

Thats reasonable, I'll include it in a v2.

Greetings,
Rouven


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Re: [PATCH 3/6] serial_ns16550: add raspberry pi compatible and init

[Sascha Hauer]

On Wed, Dec 12, 2018 at 03:10:51PM +0100, Rouven Czerwinski wrote:
> Add the compatible for the Raspberry Pi AUX UART and an init function which
> enables it via the aux register and configures the correct shift value.
> 
> Signed-off-by: Rouven Czerwinski <r.czerwinski@pengutronix.de>
> ---
>  drivers/serial/serial_ns16550.c | 20 ++++++++++++++++++++
>  1 file changed, 20 insertions(+)
> 
> diff --git a/drivers/serial/serial_ns16550.c b/drivers/serial/serial_ns16550.c
> index 8ddcfdbef..e872fb886 100644
> --- a/drivers/serial/serial_ns16550.c
> +++ b/drivers/serial/serial_ns16550.c
> @@ -253,6 +253,15 @@ static void ns16550_jz_init_port(struct console_device *cdev)
>  	ns16550_serial_init_port(cdev);
>  }
>  
> +static void rpi_init_port(struct console_device *cdev)
> +{
> +  struct ns16550_priv *priv = to_ns16550_priv(cdev);
> +
> +  writeb(0x01, 0x3f215004);
> +  priv->plat.shift = 2;
> +  ns16550_serial_init_port(cdev);
> +}

Please indent with tabs.

> +
>  /*********** Exposed Functions **********************************/
>  
>  /**
> @@ -353,6 +362,11 @@ static __maybe_unused struct ns16550_drvdata tegra_drvdata = {
>  	.linux_console_name = "ttyS",
>  };
>  
> +static struct ns16550_drvdata rpi_drvdata = {
> +  .init_port = rpi_init_port,
> +  .linux_console_name = "ttyS",
> +};

Here aswell.

Please add a __maybe_unused like done with the other drvdata in the
driver. Otherwise we'll generate a unused warning when RPI support is
disabled.

Sascha

> +
>  static int ns16550_init_iomem(struct device_d *dev, struct ns16550_priv *priv)
>  {
>  	struct resource *iores;
> @@ -528,6 +542,12 @@ static struct of_device_id ns16550_serial_dt_ids[] = {
>  		.data = &jz_drvdata,
>  	},
>  #endif
> +#if IS_ENABLED(CONFIG_MACH_RPI_COMMON)
> +	{
> +	  .compatible = "brcm,bcm2835-aux-uart",
> +	  .data = &rpi_drvdata,
> +	},
> +#endif
>  	{
>  		/* sentinel */
>  	},
> -- 
> 2.11.0
> 
> 
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