[PATCH] booting-without-of: add more bindings for FSL UPM driver

[PATCH] booting-without-of: add more bindings for FSL UPM driver

[Wolfgang Grandegger]

This patch adds the bindings for the property "chip-delay" used by
the patch "[NAND] driver extension to support NAND on TQM85xx modules" 
posted to this list a few minutes ago:

      http://ozlabs.org/pipermail/linuxppc-dev/2008-June/057632.html

Note: this patch is based on the following patches from Anton
      Vorontsov posted to this list some time ago:

      http://ozlabs.org/pipermail/linuxppc-dev/2008-May/056531.html
      http://ozlabs.org/pipermail/linuxppc-dev/2008-June/057244.html

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
---
 Documentation/powerpc/booting-without-of.txt |    1 +
 1 file changed, 1 insertion(+)

Index: linux-2.6-galak/Documentation/powerpc/booting-without-of.txt
===================================================================
--- linux-2.6-galak.orig/Documentation/powerpc/booting-without-of.txt
+++ linux-2.6-galak/Documentation/powerpc/booting-without-of.txt
@@ -3007,6 +3007,7 @@ platforms are moved over to use the flat
       - reg : should specify localbus chip select and size used for the chip.
       - fsl,upm-addr-offset : UPM pattern offset for the address latch.
       - fsl,upm-cmd-offset : UPM pattern offset for the command latch.
+      - chip-delay : may specify a delay value in milliseconds.
       - gpios : may specify optional GPIO connected to the Ready-Not-Busy pin.
 
       Example:

Re: [PATCH] booting-without-of: add more bindings for FSL UPM driver

[Segher Boessenkool]

> +      - chip-delay : may specify a delay value in milliseconds.

Delay for what?  The binding should say.  "chip-delay" is a bit
too generic name as well, it could be more descriptive perhaps.

Shouldn't this be a property of the NAND device anyway, not the
NAND controller?


Segher

Re: [PATCH] booting-without-of: add more bindings for FSL UPM driver

[Wolfgang Grandegger]

Segher Boessenkool wrote:
>> +      - chip-delay : may specify a delay value in milliseconds.
> 
> Delay for what?  The binding should say.  "chip-delay" is a bit
> too generic name as well, it could be more descriptive perhaps.

The chip-delay property defines an appropriate maximum delay 
time (tR) required for read operations if the R/B pin is not
connected. It's used as shown below:

+		/* Note: NAND support needs to be enabled in U-Boot */
+		upm@3,0 {
+			#address-cells = <0>;
+			#size-cells = <0>;
+			compatible = "fsl,upm-nand";
+			reg = <3 0x0 0x800>;
+			fsl,upm-addr-offset = <0x10>;
+			fsl,upm-cmd-offset = <0x08>;
+			chip-delay = <25>; // in micro-seconds
+
+			nand@0 {
+				#address-cells = <1>;
+				#size-cells = <1>;
+
+				partition@0 {
+					    label = "fs";
+					    reg = <0x00000000 0x01000000>;
+				};
+			};
+		};
+	};
+

> Shouldn't this be a property of the NAND device anyway, not the
> NAND controller?

Strictly speaking, it's a property of the NAND device. Therefore it 
should be inside the node nand@0, I thhink:

+			nand@0 {
+				#address-cells = <1>;
+				#size-cells = <1>;
+			        chip-delay = <25>; // in micro-seconds
+
+				partition@0 {
+					    label = "fs";
+					    reg = <0x00000000 0x01000000>;
+				};
+			};

Where should that be documented?

Wolfgang.

Re: [PATCH] booting-without-of: add more bindings for FSL UPM driver

[Segher Boessenkool]

>>> +      - chip-delay : may specify a delay value in milliseconds.
>>
>> Delay for what?  The binding should say.  "chip-delay" is a bit
>> too generic name as well, it could be more descriptive perhaps.
>
> The chip-delay property defines an appropriate maximum delay
> time (tR) required for read operations if the R/B pin is not
> connected.

Yeah.  So please put that in the binding.

>> Shouldn't this be a property of the NAND device anyway, not the
>> NAND controller?
>
> Strictly speaking, it's a property of the NAND device. Therefore it
> should be inside the node nand@0, I thhink:
>
> +			nand@0 {
> +				#address-cells = <1>;
> +				#size-cells = <1>;
> +			        chip-delay = <25>; // in micro-seconds

Something like that, yes.  You wrote milliseconds before; which is it?

And, a better property name, please.

> Where should that be documented?

In the binding for nand devices.  If there isn't any yet, it might be
best to include that with the binding for your nand controller (i.e.,
describe the whole sub node there).


Segher

Re: [PATCH] booting-without-of: add more bindings for FSL UPM driver

[Wolfgang Grandegger]

Segher Boessenkool wrote:
>>>> +      - chip-delay : may specify a delay value in milliseconds.
>>>
>>> Delay for what?  The binding should say.  "chip-delay" is a bit
>>> too generic name as well, it could be more descriptive perhaps.
>>
>> The chip-delay property defines an appropriate maximum delay
>> time (tR) required for read operations if the R/B pin is not
>> connected.
> 
> Yeah.  So please put that in the binding.
> 
>>> Shouldn't this be a property of the NAND device anyway, not the
>>> NAND controller?
>>
>> Strictly speaking, it's a property of the NAND device. Therefore it
>> should be inside the node nand@0, I thhink:
>>
>> +            nand@0 {
>> +                #address-cells = <1>;
>> +                #size-cells = <1>;
>> +                    chip-delay = <25>; // in micro-seconds
> 
> Something like that, yes.  You wrote milliseconds before; which is it?

Oops, it's in micro-seconds.

> And, a better property name, please.

Here is what we speak about (from the NAND chip manual):

  "After a READ command is sent to the memory device, data is
   transferred from the memory array to the data register in tR.
   Typically tR is 25us. The READ STATUS (70h) command or the R/B#
   signal can be used to determine when the device is ready."

And in the NAND header file "chip-delay" is documented as shown below:

  "chip_delay: [BOARDSPECIFIC] chip dependent delay for transfering data 
               from array to read regs (tR)"

The name "read-fetch-time" sounds more reasonable too me, but English
is not my native language.

>> Where should that be documented?
> 
> In the binding for nand devices.  If there isn't any yet, it might be
> best to include that with the binding for your nand controller (i.e.,
> describe the whole sub node there).

OK, here is a my proposal:

    x) Freescale Localbus UPM programmed to work with NAND flash

      Required properties:
      - compatible : "fsl,upm-nand".
      - reg : should specify localbus chip select and size used for the chip.
      - fsl,upm-addr-offset : UPM pattern offset for the address latch.
      - fsl,upm-cmd-offset : UPM pattern offset for the command latch.
      - gpios : may specify optional GPIO connected to the Ready-Not-Busy pin.

      Each NAND flash device is represented as a sub-node of the UPM node.
      The nodes's name represents the name of the corresponding device.

      NAND flash properties:
      - compatible: not yet used.
      - read-fetch-delay: chip dependent delay for transfering data 
        from array to read regs (tR) im micro-seconds.
 
      Each partition is represented as a sub-node of the NAND flash device.
      Each node's name represents the name of the corresponding partition
      of the NAND flash device.

      NAND flash partitions:
      - reg : The partition's offset and size within the flash bank.
      - label : (optional) The label / name for this flash partition.
        If omitted, the label is taken from the node name (excluding
        the unit address).
      - read-only : (optional) This parameter, if present, is a hint to
        Linux that this flash partition should only be mounted
        read-only.  This is usually used for flash partitions
        containing early-boot firmware images or data which should not
        be clobbered.
 
      Example:

	upm@1,0 {
		compatible = "fsl,upm-nand";
		reg = <1 0 1>;
		fsl,upm-addr-offset = <16>;
		fsl,upm-cmd-offset = <8>;
		gpios = <&qe_pio_e 18 0>;

		flash {
			#address-cells = <1>;
			#size-cells = <1>;
			compatible = "stmicro,NAND512W3A2BN6E";
			read-fetch-delay = 25

			fs@0 {
				label = "fs";
				reg = <0 f80000>;
			};

			firmware@f80000 {
				label ="firmware";
				reg = <f80000 80000>;
				read-only;
			};
		};
	};

What do you think?

Wolfgang.

Re: [PATCH] booting-without-of: add more bindings for FSL UPM driver

[Wolfgang Grandegger]

Hi Segher,

Segher Boessenkool wrote:
>>>> +      - chip-delay : may specify a delay value in milliseconds.
>>>
>>> Delay for what?  The binding should say.  "chip-delay" is a bit
>>> too generic name as well, it could be more descriptive perhaps.
>>
>> The chip-delay property defines an appropriate maximum delay
>> time (tR) required for read operations if the R/B pin is not
>> connected.
> 
> Yeah.  So please put that in the binding.
> 
>>> Shouldn't this be a property of the NAND device anyway, not the
>>> NAND controller?
>>
>> Strictly speaking, it's a property of the NAND device. Therefore it
>> should be inside the node nand@0, I thhink:
>>
>> +            nand@0 {
>> +                #address-cells = <1>;
>> +                #size-cells = <1>;
>> +                    chip-delay = <25>; // in micro-seconds
> 
> Something like that, yes.  You wrote milliseconds before; which is it?
> 
> And, a better property name, please.
> 
>> Where should that be documented?
> 
> In the binding for nand devices.  If there isn't any yet, it might be
> best to include that with the binding for your nand controller (i.e.,
> describe the whole sub node there).

This is another try to get this binding accepted. Below is my revised
patch introducing the proper "read-fetch-delay" for the sub-nodes of
the FSL UPM nodes and documenting all other options as well.

What do you think?

Wolfgang.


From: Wolfgang Grandegger <wg@grandegger.com>
Subject: booting-without-of: add more bindings for FSL UPM driver

This patch adds the bindings for the property "read-fetch-delay" to the
sub-nodes of the "fsl,upm-nand" compatible nodes. It is used by the patch
"[NAND] driver extension to support NAND on TQM85xx modules" posted to
this list some time ago:

      http://ozlabs.org/pipermail/linuxppc-dev/2008-June/057632.html

Furthermore it documents all other properties of the sub-nodes.

Note: this patch is based on the following patches from Anton
      Vorontsov posted to this list some time ago:

      http://ozlabs.org/pipermail/linuxppc-dev/2008-May/056531.html
      http://ozlabs.org/pipermail/linuxppc-dev/2008-June/057244.html

Signed-off-by: Wolfgang Grandegger <wg@grandegger.com>
---
 Documentation/powerpc/booting-without-of.txt |   34 +++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

Index: linux-2.6-galak/Documentation/powerpc/booting-without-of.txt
===================================================================
--- linux-2.6-galak.orig/Documentation/powerpc/booting-without-of.txt
+++ linux-2.6-galak/Documentation/powerpc/booting-without-of.txt
@@ -3036,6 +3036,28 @@ platforms are moved over to use the flat
       - fsl,upm-cmd-offset : UPM pattern offset for the command latch.
       - gpios : may specify optional GPIO connected to the Ready-Not-Busy pin.
 
+      Each NAND flash is represented as a sub-node of the UPM node.
+      The nodes's name represents the name of the corresponding device.
+
+      NAND flash properties:
+      - compatible : not yet used.
+      - read-fetch-delay : chip dependent delay for transfering data
+        from array to read regs (tR).
+
+      Each partition is represented as a sub-node of the NAND flash device.
+      Each node's name represents the name of the corresponding partition
+      of the flash device.
+
+      NAND flash partitions:
+      - reg : The partition's offset and size within the flash bank.
+      - label : (optional) The label / name for this flash partition. If
+        omitted, the label is taken from the node name (excluding the
+        unit address).
+      - read-only : (optional) This parameter, if present, is a hint to
+        Linux that this flash partition should only be mounted read-only.
+        This is usually used for flash partitions containing early-boot
+        firmware images or data which should not be clobbered.
+
       Example:
 
 	upm@1,0 {
@@ -3049,9 +3071,17 @@ platforms are moved over to use the flat
 			#address-cells = <1>;
 			#size-cells = <1>;
 			compatible = "stmicro,NAND512W3A2BN6E";
+			read-fetch-delay = 25
+
+			fs@0 {
+				label = "fs";
+				reg = <0 f80000>;
+			};
 
-			partition@0 {
-				...
+			firmware@f80000 {
+				label ="firmware";
+				reg = <f80000 80000>;
+				read-only;
 			};
 		};
 	};