[PATCH 0/3] serial: earlycon: Add device-tree support for earlycon on Tegra

[PATCH 0/3] serial: earlycon: Add device-tree support for earlycon on Tegra

[Jon Hunter]

For Tegra the early console is support by passing the console information
via the boot parameter earlycon. This series allows us to use the
device-tree "stdout-path" property for early console (as well as the
console) on Tegra.

Jon Hunter (3):
  serial: earlycon: Add device-tree support for other IO types
  serial: 8250_early: Add support for regshift
  serial: 8250_early: Add earlycon support for Tegra

 drivers/of/fdt.c                     | 26 +++++++++++++++++++++++-
 drivers/tty/serial/8250/8250_early.c | 38 ++++++++++++++++++++++++++----------
 drivers/tty/serial/earlycon.c        |  6 ++++--
 include/linux/serial_core.h          |  3 ++-
 4 files changed, 59 insertions(+), 14 deletions(-)

-- 
2.1.4

[PATCH 1/3] serial: earlycon: Add device-tree support for other IO types

[Jon Hunter]

When early console are registered via device-tree, currently it is assumed
that the console iotype is UPIO_MEM and the regshift is 0. This is not the
case for all devices and so add support for reading the device-tree
properties "reg-io-width" and "reg-shift" so that the appropriate iotype
and regshift can be specified for a given device.

Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
 drivers/of/fdt.c              | 26 +++++++++++++++++++++++++-
 drivers/tty/serial/earlycon.c |  6 ++++--
 include/linux/serial_core.h   |  3 ++-
 3 files changed, 31 insertions(+), 4 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 655f79db7899..f69406e42631 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -827,7 +827,9 @@ static int __init early_init_dt_scan_chosen_serial(void)
 		return -ENODEV;
 
 	while (match->compatible[0]) {
+		const __be32 *prop;
 		u64 addr;
+		u8 iotype, regshift;
 
 		if (fdt_node_check_compatible(fdt, offset, match->compatible)) {
 			match++;
@@ -838,7 +840,29 @@ static int __init early_init_dt_scan_chosen_serial(void)
 		if (addr == OF_BAD_ADDR)
 			return -ENXIO;
 
-		of_setup_earlycon(addr, match->data);
+		prop = fdt_getprop(fdt, offset, "reg-shift", NULL);
+		regshift = prop ? be32_to_cpup(prop) : 0;
+
+		prop = fdt_getprop(fdt, offset, "reg-io-width", NULL);
+		if (prop) {
+			switch (be32_to_cpup(prop)) {
+			case 1:
+				iotype = UPIO_MEM;
+				break;
+			case 2:
+				iotype = UPIO_MEM16;
+				break;
+			case 4:
+				iotype = UPIO_MEM32;
+				break;
+			default:
+				return -EINVAL;
+			}
+		} else {
+			iotype = UPIO_MEM;
+		}
+
+		of_setup_earlycon(addr, iotype, regshift, match->data);
 		return 0;
 	}
 	return -ENODEV;
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 3f2423690d01..2fd2f19d7091 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -204,17 +204,19 @@ static int __init param_setup_earlycon(char *buf)
 }
 early_param("earlycon", param_setup_earlycon);
 
-int __init of_setup_earlycon(unsigned long addr,
+int __init of_setup_earlycon(unsigned long addr, unsigned char iotype,
+			     unsigned char regshift,
 			     int (*setup)(struct earlycon_device *, const char *))
 {
 	int err;
 	struct uart_port *port = &early_console_dev.port;
 
 	spin_lock_init(&port->lock);
-	port->iotype = UPIO_MEM;
+	port->iotype = iotype;
 	port->mapbase = addr;
 	port->uartclk = BASE_BAUD * 16;
 	port->membase = earlycon_map(addr, SZ_4K);
+	port->regshift = regshift;
 
 	early_console_dev.con->data = &early_console_dev;
 	err = setup(&early_console_dev, NULL);
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index e03d6ba5e5b4..e0e1c7ef2856 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -346,7 +346,8 @@ struct earlycon_id {
 } __aligned(32);
 
 extern int setup_earlycon(char *buf);
-extern int of_setup_earlycon(unsigned long addr,
+extern int of_setup_earlycon(unsigned long addr, unsigned char iotype,
+			     unsigned char regshift,
 			     int (*setup)(struct earlycon_device *, const char *));
 
 #define EARLYCON_DECLARE(_name, func)					\
-- 
2.1.4

[PATCH 2/3] serial: 8250_early: Add support for regshift

[Jon Hunter]

The 8250 early console assumes a default regshift for each iotype. This
does not work for all devices. For example, Tegra UARTs use a iotype of
UPIO_MEM with a regshift of 2 because the registers are 32-bit aligned
and permit byte access.

If the regshift is specified (for example, via device-tree), then use the
value provided and otherwise revert to the defaults assumed for each
iotype.

Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
Please note that today for Tegra, early console is supported by passing
the boot parameter "earlycon=uart8250,mmio32,0xXXXXXXXX". While this works
and we could use UPIO_MEM32 for tegra, this would mean changing all the
DT source files for Tegra to add the "reg-io-width" property. IMO it seems
better to make early console for 8250 work in the same way as the normal
8250 console and support regshift.

 drivers/tty/serial/8250/8250_early.c | 36 ++++++++++++++++++++++++++----------
 1 file changed, 26 insertions(+), 10 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index af62131af21e..758054957788 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -41,15 +41,15 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
 {
 	switch (port->iotype) {
 	case UPIO_MEM:
-		return readb(port->membase + offset);
+		return readb(port->membase + (offset << port->regshift));
 	case UPIO_MEM16:
-		return readw(port->membase + (offset << 1));
+		return readw(port->membase + (offset << port->regshift));
 	case UPIO_MEM32:
-		return readl(port->membase + (offset << 2));
+		return readl(port->membase + (offset << port->regshift));
 	case UPIO_MEM32BE:
-		return ioread32be(port->membase + (offset << 2));
+		return ioread32be(port->membase + (offset << port->regshift));
 	case UPIO_PORT:
-		return inb(port->iobase + offset);
+		return inb(port->iobase + (offset << port->regshift));
 	default:
 		return 0;
 	}
@@ -59,19 +59,19 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
 {
 	switch (port->iotype) {
 	case UPIO_MEM:
-		writeb(value, port->membase + offset);
+		writeb(value, port->membase + (offset << port->regshift));
 		break;
 	case UPIO_MEM16:
-		writew(value, port->membase + (offset << 1));
+		writew(value, port->membase + (offset << port->regshift));
 		break;
 	case UPIO_MEM32:
-		writel(value, port->membase + (offset << 2));
+		writel(value, port->membase + (offset << port->regshift));
 		break;
 	case UPIO_MEM32BE:
-		iowrite32be(value, port->membase + (offset << 2));
+		iowrite32be(value, port->membase + (offset << port->regshift));
 		break;
 	case UPIO_PORT:
-		outb(value, port->iobase + offset);
+		outb(value, port->iobase + (offset << port->regshift));
 		break;
 	}
 }
@@ -128,6 +128,22 @@ int __init early_serial8250_setup(struct earlycon_device *device,
 	if (!(device->port.membase || device->port.iobase))
 		return -ENODEV;
 
+	/*
+	 * If regshift is not specified, then assume the
+	 * following defaults for the below iotypes.
+	 */
+	if (!device->port.regshift) {
+		switch (device->port.iotype) {
+		case UPIO_MEM16:
+			device->port.regshift = 1;
+			break;
+		case UPIO_MEM32:
+		case UPIO_MEM32BE:
+			device->port.regshift = 2;
+			break;
+		}
+	}
+
 	if (!device->baud) {
 		struct uart_port *port = &device->port;
 		unsigned int ier;
-- 
2.1.4

[PATCH 3/3] serial: 8250_early: Add earlycon support for Tegra

[Jon Hunter]

Declare an OF early console for Tegra so that the early console device
can be specified via the "stdout-path" property in device-tree.

Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
 drivers/tty/serial/8250/8250_early.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 758054957788..23283a1392a8 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -161,3 +161,5 @@ EARLYCON_DECLARE(uart8250, early_serial8250_setup);
 EARLYCON_DECLARE(uart, early_serial8250_setup);
 OF_EARLYCON_DECLARE(ns16550, "ns16550", early_serial8250_setup);
 OF_EARLYCON_DECLARE(ns16550a, "ns16550a", early_serial8250_setup);
+OF_EARLYCON_DECLARE(tegra20_uart, "nvidia,tegra20-uart",
+		    early_serial8250_setup);
-- 
2.1.4

Re: [PATCH 0/3] serial: earlycon: Add device-tree support for earlycon on Tegra

[Arnd Bergmann]

On Tuesday 12 January 2016 10:33:26 Jon Hunter wrote:
> For Tegra the early console is support by passing the console information
> via the boot parameter earlycon. This series allows us to use the
> device-tree "stdout-path" property for early console (as well as the
> console) on Tegra.
> 

Hi Jon,

I like this version, nice work!

Acked-by: Arnd Bergmann <arnd-r2nGTMty4D4@public.gmane.org>
--
To unsubscribe from this list: send the line "unsubscribe devicetree" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [PATCH 2/3] serial: 8250_early: Add support for regshift

[Peter Hurley]

Hi Jon,

On 01/12/2016 02:33 AM, Jon Hunter wrote:
> The 8250 early console assumes a default regshift for each iotype. This
> does not work for all devices. For example, Tegra UARTs use a iotype of
> UPIO_MEM with a regshift of 2 because the registers are 32-bit aligned
> and permit byte access.
> 
> If the regshift is specified (for example, via device-tree), then use the
> value provided and otherwise revert to the defaults assumed for each
> iotype.
> 
> Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
> Please note that today for Tegra, early console is supported by passing
> the boot parameter "earlycon=uart8250,mmio32,0xXXXXXXXX". While this works
> and we could use UPIO_MEM32 for tegra, this would mean changing all the
> DT source files for Tegra to add the "reg-io-width" property. IMO it seems
> better to make early console for 8250 work in the same way as the normal
> 8250 console and support regshift.
> 
>  drivers/tty/serial/8250/8250_early.c | 36 ++++++++++++++++++++++++++----------
>  1 file changed, 26 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
> index af62131af21e..758054957788 100644
> --- a/drivers/tty/serial/8250/8250_early.c
> +++ b/drivers/tty/serial/8250/8250_early.c
> @@ -41,15 +41,15 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
>  {
>  	switch (port->iotype) {
>  	case UPIO_MEM:
> -		return readb(port->membase + offset);
> +		return readb(port->membase + (offset << port->regshift));
>  	case UPIO_MEM16:
> -		return readw(port->membase + (offset << 1));
> +		return readw(port->membase + (offset << port->regshift));
>  	case UPIO_MEM32:
> -		return readl(port->membase + (offset << 2));
> +		return readl(port->membase + (offset << port->regshift));
>  	case UPIO_MEM32BE:
> -		return ioread32be(port->membase + (offset << 2));
> +		return ioread32be(port->membase + (offset << port->regshift));
>  	case UPIO_PORT:
> -		return inb(port->iobase + offset);
> +		return inb(port->iobase + (offset << port->regshift));
>  	default:
>  		return 0;
>  	}
> @@ -59,19 +59,19 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
>  {
>  	switch (port->iotype) {
>  	case UPIO_MEM:
> -		writeb(value, port->membase + offset);
> +		writeb(value, port->membase + (offset << port->regshift));
>  		break;
>  	case UPIO_MEM16:
> -		writew(value, port->membase + (offset << 1));
> +		writew(value, port->membase + (offset << port->regshift));
>  		break;
>  	case UPIO_MEM32:
> -		writel(value, port->membase + (offset << 2));
> +		writel(value, port->membase + (offset << port->regshift));
>  		break;
>  	case UPIO_MEM32BE:
> -		iowrite32be(value, port->membase + (offset << 2));
> +		iowrite32be(value, port->membase + (offset << port->regshift));
>  		break;
>  	case UPIO_PORT:
> -		outb(value, port->iobase + offset);
> +		outb(value, port->iobase + (offset << port->regshift));
>  		break;
>  	}
>  }
> @@ -128,6 +128,22 @@ int __init early_serial8250_setup(struct earlycon_device *device,
>  	if (!(device->port.membase || device->port.iobase))
>  		return -ENODEV;
>  
> +	/*
> +	 * If regshift is not specified, then assume the
> +	 * following defaults for the below iotypes.
> +	 */
> +	if (!device->port.regshift) {
> +		switch (device->port.iotype) {
> +		case UPIO_MEM16:
> +			device->port.regshift = 1;
> +			break;
> +		case UPIO_MEM32:
> +		case UPIO_MEM32BE:
> +			device->port.regshift = 2;
> +			break;
> +		}
> +	}

Since the earlycon command line parsing sets port->regshift, the only possible
path requiring defaults would be DT, but 8250 DT should not have default
regshift based on the iotype; the 8250 port driver doesn't.

Regards,
Peter Hurley

> +
>  	if (!device->baud) {
>  		struct uart_port *port = &device->port;
>  		unsigned int ier;
> 

Re: [PATCH 2/3] serial: 8250_early: Add support for regshift

[Jon Hunter]

Hi Peter,

On 12/01/16 16:15, Peter Hurley wrote:
> Hi Jon,
> 
> On 01/12/2016 02:33 AM, Jon Hunter wrote:
>> The 8250 early console assumes a default regshift for each iotype. This
>> does not work for all devices. For example, Tegra UARTs use a iotype of
>> UPIO_MEM with a regshift of 2 because the registers are 32-bit aligned
>> and permit byte access.
>>
>> If the regshift is specified (for example, via device-tree), then use the
>> value provided and otherwise revert to the defaults assumed for each
>> iotype.
>>
>> Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>> ---
>> Please note that today for Tegra, early console is supported by passing
>> the boot parameter "earlycon=uart8250,mmio32,0xXXXXXXXX". While this works
>> and we could use UPIO_MEM32 for tegra, this would mean changing all the
>> DT source files for Tegra to add the "reg-io-width" property. IMO it seems
>> better to make early console for 8250 work in the same way as the normal
>> 8250 console and support regshift.
>>
>>  drivers/tty/serial/8250/8250_early.c | 36 ++++++++++++++++++++++++++----------
>>  1 file changed, 26 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
>> index af62131af21e..758054957788 100644
>> --- a/drivers/tty/serial/8250/8250_early.c
>> +++ b/drivers/tty/serial/8250/8250_early.c
>> @@ -41,15 +41,15 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
>>  {
>>  	switch (port->iotype) {
>>  	case UPIO_MEM:
>> -		return readb(port->membase + offset);
>> +		return readb(port->membase + (offset << port->regshift));
>>  	case UPIO_MEM16:
>> -		return readw(port->membase + (offset << 1));
>> +		return readw(port->membase + (offset << port->regshift));
>>  	case UPIO_MEM32:
>> -		return readl(port->membase + (offset << 2));
>> +		return readl(port->membase + (offset << port->regshift));
>>  	case UPIO_MEM32BE:
>> -		return ioread32be(port->membase + (offset << 2));
>> +		return ioread32be(port->membase + (offset << port->regshift));
>>  	case UPIO_PORT:
>> -		return inb(port->iobase + offset);
>> +		return inb(port->iobase + (offset << port->regshift));
>>  	default:
>>  		return 0;
>>  	}
>> @@ -59,19 +59,19 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
>>  {
>>  	switch (port->iotype) {
>>  	case UPIO_MEM:
>> -		writeb(value, port->membase + offset);
>> +		writeb(value, port->membase + (offset << port->regshift));
>>  		break;
>>  	case UPIO_MEM16:
>> -		writew(value, port->membase + (offset << 1));
>> +		writew(value, port->membase + (offset << port->regshift));
>>  		break;
>>  	case UPIO_MEM32:
>> -		writel(value, port->membase + (offset << 2));
>> +		writel(value, port->membase + (offset << port->regshift));
>>  		break;
>>  	case UPIO_MEM32BE:
>> -		iowrite32be(value, port->membase + (offset << 2));
>> +		iowrite32be(value, port->membase + (offset << port->regshift));
>>  		break;
>>  	case UPIO_PORT:
>> -		outb(value, port->iobase + offset);
>> +		outb(value, port->iobase + (offset << port->regshift));
>>  		break;
>>  	}
>>  }
>> @@ -128,6 +128,22 @@ int __init early_serial8250_setup(struct earlycon_device *device,
>>  	if (!(device->port.membase || device->port.iobase))
>>  		return -ENODEV;
>>  
>> +	/*
>> +	 * If regshift is not specified, then assume the
>> +	 * following defaults for the below iotypes.
>> +	 */
>> +	if (!device->port.regshift) {
>> +		switch (device->port.iotype) {
>> +		case UPIO_MEM16:
>> +			device->port.regshift = 1;
>> +			break;
>> +		case UPIO_MEM32:
>> +		case UPIO_MEM32BE:
>> +			device->port.regshift = 2;
>> +			break;
>> +		}
>> +	}
> 
> Since the earlycon command line parsing sets port->regshift, the only possible
> path requiring defaults would be DT, but 8250 DT should not have default
> regshift based on the iotype; the 8250 port driver doesn't.

Ah, I see, I missed that. However, for command line parsing, I only see
regshift being set to 2 for mmio32 (and I guess it will be 0 otherwise).
Is mmio16 not supported for command line parsing?

Ok, I will drop the above hunk.

Cheers
Jon

Re: [PATCH 2/3] serial: 8250_early: Add support for regshift

[Peter Hurley]

On 01/12/2016 10:28 AM, Jon Hunter wrote:
> Hi Peter,
> 
> On 12/01/16 16:15, Peter Hurley wrote:
>> Hi Jon,
>>
>> On 01/12/2016 02:33 AM, Jon Hunter wrote:
>>> The 8250 early console assumes a default regshift for each iotype. This
>>> does not work for all devices. For example, Tegra UARTs use a iotype of
>>> UPIO_MEM with a regshift of 2 because the registers are 32-bit aligned
>>> and permit byte access.
>>>
>>> If the regshift is specified (for example, via device-tree), then use the
>>> value provided and otherwise revert to the defaults assumed for each
>>> iotype.
>>>
>>> Signed-off-by: Jon Hunter <jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>> ---
>>> Please note that today for Tegra, early console is supported by passing
>>> the boot parameter "earlycon=uart8250,mmio32,0xXXXXXXXX". While this works
>>> and we could use UPIO_MEM32 for tegra, this would mean changing all the
>>> DT source files for Tegra to add the "reg-io-width" property. IMO it seems
>>> better to make early console for 8250 work in the same way as the normal
>>> 8250 console and support regshift.
>>>
>>>  drivers/tty/serial/8250/8250_early.c | 36 ++++++++++++++++++++++++++----------
>>>  1 file changed, 26 insertions(+), 10 deletions(-)
>>>
>>> diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
>>> index af62131af21e..758054957788 100644
>>> --- a/drivers/tty/serial/8250/8250_early.c
>>> +++ b/drivers/tty/serial/8250/8250_early.c
>>> @@ -41,15 +41,15 @@ static unsigned int __init serial8250_early_in(struct uart_port *port, int offse
>>>  {
>>>  	switch (port->iotype) {
>>>  	case UPIO_MEM:
>>> -		return readb(port->membase + offset);
>>> +		return readb(port->membase + (offset << port->regshift));
>>>  	case UPIO_MEM16:
>>> -		return readw(port->membase + (offset << 1));
>>> +		return readw(port->membase + (offset << port->regshift));
>>>  	case UPIO_MEM32:
>>> -		return readl(port->membase + (offset << 2));
>>> +		return readl(port->membase + (offset << port->regshift));
>>>  	case UPIO_MEM32BE:
>>> -		return ioread32be(port->membase + (offset << 2));
>>> +		return ioread32be(port->membase + (offset << port->regshift));
>>>  	case UPIO_PORT:
>>> -		return inb(port->iobase + offset);
>>> +		return inb(port->iobase + (offset << port->regshift));
>>>  	default:
>>>  		return 0;
>>>  	}
>>> @@ -59,19 +59,19 @@ static void __init serial8250_early_out(struct uart_port *port, int offset, int
>>>  {
>>>  	switch (port->iotype) {
>>>  	case UPIO_MEM:
>>> -		writeb(value, port->membase + offset);
>>> +		writeb(value, port->membase + (offset << port->regshift));
>>>  		break;
>>>  	case UPIO_MEM16:
>>> -		writew(value, port->membase + (offset << 1));
>>> +		writew(value, port->membase + (offset << port->regshift));
>>>  		break;
>>>  	case UPIO_MEM32:
>>> -		writel(value, port->membase + (offset << 2));
>>> +		writel(value, port->membase + (offset << port->regshift));
>>>  		break;
>>>  	case UPIO_MEM32BE:
>>> -		iowrite32be(value, port->membase + (offset << 2));
>>> +		iowrite32be(value, port->membase + (offset << port->regshift));
>>>  		break;
>>>  	case UPIO_PORT:
>>> -		outb(value, port->iobase + offset);
>>> +		outb(value, port->iobase + (offset << port->regshift));
>>>  		break;
>>>  	}
>>>  }
>>> @@ -128,6 +128,22 @@ int __init early_serial8250_setup(struct earlycon_device *device,
>>>  	if (!(device->port.membase || device->port.iobase))
>>>  		return -ENODEV;
>>>  
>>> +	/*
>>> +	 * If regshift is not specified, then assume the
>>> +	 * following defaults for the below iotypes.
>>> +	 */
>>> +	if (!device->port.regshift) {
>>> +		switch (device->port.iotype) {
>>> +		case UPIO_MEM16:
>>> +			device->port.regshift = 1;
>>> +			break;
>>> +		case UPIO_MEM32:
>>> +		case UPIO_MEM32BE:
>>> +			device->port.regshift = 2;
>>> +			break;
>>> +		}
>>> +	}
>>
>> Since the earlycon command line parsing sets port->regshift, the only possible
>> path requiring defaults would be DT, but 8250 DT should not have default
>> regshift based on the iotype; the 8250 port driver doesn't.
> 
> Ah, I see, I missed that. However, for command line parsing, I only see
> regshift being set to 2 for mmio32 (and I guess it will be 0 otherwise).

Exactly. Currently unrepresented is 8-bit wide, 32-bit aligned mmio.

> Is mmio16 not supported for command line parsing?

In Greg's tty-next branch @
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git

commit bd94c4077a0b2ecc35562c294f80f3659ecd8499
Author: Masahiro Yamada <yamada.masahiro-uWyLwvC0a2jby3iVrkZq2A@public.gmane.org>
Date:   Wed Oct 28 12:46:05 2015 +0900

    serial: support 16-bit register interface for console
    
    Currently, 8-bit (MMIO) and 32-bit (MMIO32) register interfaces are
    supported for the 8250 console, but the 16-bit (MMIO16) is not.
    The 8250 UART device on my board is connected to a 16-bit bus and
    my main motivation is to use earlycon with it.
    (Refer to arch/arm/boot/dts/uniphier-support-card.dtsi)
    
    Signed-off-by: Masahiro Yamada <yamada.masahiro-uWyLwvC0a2jby3iVrkZq2A@public.gmane.org>
    Reviewed-by: Peter Hurley <peter-WaGBZJeGNqdsbIuE7sb01tBPR1lH4CV8@public.gmane.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>

Regards,
Peter Hurley

> Ok, I will drop the above hunk.
> 
> Cheers
> Jon
> 

Re: [PATCH 0/3] serial: earlycon: Add device-tree support for earlycon on Tegra

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1011 bytes --]

On Tue, Jan 12, 2016 at 10:33:26AM +0000, Jon Hunter wrote:
> For Tegra the early console is support by passing the console information
> via the boot parameter earlycon. This series allows us to use the
> device-tree "stdout-path" property for early console (as well as the
> console) on Tegra.
> 
> Jon Hunter (3):
>   serial: earlycon: Add device-tree support for other IO types
>   serial: 8250_early: Add support for regshift
>   serial: 8250_early: Add earlycon support for Tegra
> 
>  drivers/of/fdt.c                     | 26 +++++++++++++++++++++++-
>  drivers/tty/serial/8250/8250_early.c | 38 ++++++++++++++++++++++++++----------
>  drivers/tty/serial/earlycon.c        |  6 ++++--
>  include/linux/serial_core.h          |  3 ++-
>  4 files changed, 59 insertions(+), 14 deletions(-)

The series:

Acked-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

Jon, do you have plans on adding the stdout-path properties to existing
device tree files?

Thierry

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

Re: [PATCH 0/3] serial: earlycon: Add device-tree support for earlycon on Tegra

[Jon Hunter]

On 13/01/16 16:03, Thierry Reding wrote:
> * PGP Signed by an unknown key
> 
> On Tue, Jan 12, 2016 at 10:33:26AM +0000, Jon Hunter wrote:
>> For Tegra the early console is support by passing the console information
>> via the boot parameter earlycon. This series allows us to use the
>> device-tree "stdout-path" property for early console (as well as the
>> console) on Tegra.
>>
>> Jon Hunter (3):
>>   serial: earlycon: Add device-tree support for other IO types
>>   serial: 8250_early: Add support for regshift
>>   serial: 8250_early: Add earlycon support for Tegra
>>
>>  drivers/of/fdt.c                     | 26 +++++++++++++++++++++++-
>>  drivers/tty/serial/8250/8250_early.c | 38 ++++++++++++++++++++++++++----------
>>  drivers/tty/serial/earlycon.c        |  6 ++++--
>>  include/linux/serial_core.h          |  3 ++-
>>  4 files changed, 59 insertions(+), 14 deletions(-)
> 
> The series:
> 
> Acked-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

Thanks. However, Peter Hurley also has a series he just refreshed from
early last year that includes similar changes to patches 1 and 2 [0]. So
I will probably drop these and just re-post patch 3 once his series is
merged.

> Jon, do you have plans on adding the stdout-path properties to existing
> device tree files?

I think that it would be a good idea and so I could include that in a
series with patch #3.

Cheers
Jon

[0] http://marc.info/?t=145262776100005&r=1&w=2

Re: [PATCH 0/3] serial: earlycon: Add device-tree support for earlycon on Tegra

[Thierry Reding]

[-- Attachment #1: Type: text/plain, Size: 1621 bytes --]

On Wed, Jan 13, 2016 at 05:21:54PM +0000, Jon Hunter wrote:
> 
> On 13/01/16 16:03, Thierry Reding wrote:
> > * PGP Signed by an unknown key
> > 
> > On Tue, Jan 12, 2016 at 10:33:26AM +0000, Jon Hunter wrote:
> >> For Tegra the early console is support by passing the console information
> >> via the boot parameter earlycon. This series allows us to use the
> >> device-tree "stdout-path" property for early console (as well as the
> >> console) on Tegra.
> >>
> >> Jon Hunter (3):
> >>   serial: earlycon: Add device-tree support for other IO types
> >>   serial: 8250_early: Add support for regshift
> >>   serial: 8250_early: Add earlycon support for Tegra
> >>
> >>  drivers/of/fdt.c                     | 26 +++++++++++++++++++++++-
> >>  drivers/tty/serial/8250/8250_early.c | 38 ++++++++++++++++++++++++++----------
> >>  drivers/tty/serial/earlycon.c        |  6 ++++--
> >>  include/linux/serial_core.h          |  3 ++-
> >>  4 files changed, 59 insertions(+), 14 deletions(-)
> > 
> > The series:
> > 
> > Acked-by: Thierry Reding <treding-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> 
> Thanks. However, Peter Hurley also has a series he just refreshed from
> early last year that includes similar changes to patches 1 and 2 [0]. So
> I will probably drop these and just re-post patch 3 once his series is
> merged.

Okay, sounds fine.

> > Jon, do you have plans on adding the stdout-path properties to existing
> > device tree files?
> 
> I think that it would be a good idea and so I could include that in a
> series with patch #3.

Sounds good.

Thanks,
Thierry

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 819 bytes --]