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Commit 0456d330 authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by Jason Cooper
Browse files

memory: mvebu-devbus: add a devbus, keep-config property 



Currently, the mvebu-devbus Device Tree binding makes defining the
timing parameters mandatory.

However, in practice, when converting Orion5x platforms to the Device
Tree, we may not necessarily have easy access to the hardware
platforms to fetch those values which were not defined in old-style
board files: all these platforms rely on the bootloader setting the
timing parameters correctly.

In order to facilitate the migration to the Device Tree of this
platform, this commit relaxes the mvebu-devbus Device Tree binding by
introducing a 'devbus,keep-config' boolean property, which, if
defined, will ignore all timing parameters passed in the Device Tree,
and simply rely on the timing values already defined by the
bootloader.

Signed-off-by: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: default avatarSebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Tested-by: default avatarEzequiel Garcia <ezequiel.garcia@free-electrons.com>
Link: https://lkml.kernel.org/r/1398202002-28530-10-git-send-email-thomas.petazzoni@free-electrons.com


Signed-off-by: default avatarJason Cooper <jason@lakedaemon.net>
parent c4ec7430

Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt

+18 −11
Original line number Diff line number Diff line
@@ -23,6 +23,13 @@ Required properties: 
                        integer values for each chip-select line in use:

                        0 <physical address of mapping> <size>



Optional properties:



 - devbus,keep-config   This property can optionally be used to keep

                        using the timing parameters set by the

                        bootloader. It makes all the timing properties

                        described below unused.



Timing properties for child nodes:



Read parameters:
@@ -31,26 +38,26 @@ Read parameters: 
                        drive the AD bus after the completion of a device read.

                        This prevents contentions on the Device Bus after a read

                        cycle from a slow device.

                        Mandatory.

                        Mandatory, except if devbus,keep-config is used.



 - devbus,bus-width:    Defines the bus width, in bits (e.g. <16>).

                        Mandatory.

                        Mandatory, except if devbus,keep-config is used.



 - devbus,badr-skew-ps: Defines the time delay from from A[2:0] toggle,

                        to read data sample. This parameter is useful for

                        synchronous pipelined devices, where the address

                        precedes the read data by one or two cycles.

                        Mandatory.

                        Mandatory, except if devbus,keep-config is used.



 - devbus,acc-first-ps: Defines the time delay from the negation of

                        ALE[0] to the cycle that the first read data is sampled

                        by the controller.

                        Mandatory.

                        Mandatory, except if devbus,keep-config is used.



 - devbus,acc-next-ps:  Defines the time delay between the cycle that

                        samples data N and the cycle that samples data N+1

                        (in burst accesses).

                        Mandatory.

                        Mandatory, except if devbus,keep-config is used.



 - devbus,rd-setup-ps:  Defines the time delay between DEV_CSn assertion to

			DEV_OEn assertion. If set to 0 (default),
@@ -58,8 +65,8 @@ Read parameters: 
                        This parameter has no affect on <acc-first-ps> parameter

                        (no affect on first data sample). Set <rd-setup-ps>

                        to a value smaller than <acc-first-ps>.

                        Mandatory for "marvell,mvebu-devbus"

                        compatible string, ignored otherwise.

                        Mandatory for "marvell,mvebu-devbus" compatible string,

                        except if devbus,keep-config is used.



 - devbus,rd-hold-ps:   Defines the time between the last data sample to the

			de-assertion of DEV_CSn. If set to 0 (default),
@@ -70,8 +77,8 @@ Read parameters: 
                        last data sampled. Also this parameter has no

                        affect on <turn-off-ps> parameter.

                        Set <rd-hold-ps> to a value smaller than <turn-off-ps>.

                        Mandatory for "marvell,mvebu-devbus"

                        compatible string, ignored otherwise.

                        Mandatory for "marvell,mvebu-devbus" compatible string,

                        except if devbus,keep-config is used.



Write parameters:
@@ -96,8 +103,8 @@ Write parameters: 
 - devbus,sync-enable: Synchronous device enable.

                       1: True

                       0: False

                       Mandatory for "marvell,mvebu-devbus" compatible

                       string, ignored otherwise.

                       Mandatory for "marvell,mvebu-devbus" compatible string,

                       except if devbus,keep-config is used.



An example for an Armada XP GP board, with a 16 MiB NOR device as child

is showed below. Note that the Device Bus driver is in charge of allocating

drivers/memory/mvebu-devbus.c

+11 −9
Original line number Diff line number Diff line
@@ -310,6 +310,7 @@ static int mvebu_devbus_probe(struct platform_device *pdev) 
	dev_dbg(devbus->dev, "Setting timing parameter, tick is %lu ps\n",

		devbus->tick_ps);



	if (!of_property_read_bool(node, "devbus,keep-config")) {

		/* Read the Device Tree node */

		err = devbus_get_timing_params(devbus, node, &r, &w);

		if (err < 0)
@@ -320,6 +321,7 @@ static int mvebu_devbus_probe(struct platform_device *pdev) 
			devbus_orion_set_timing_params(devbus, node, &r, &w);

		else

			devbus_armada_set_timing_params(devbus, node, &r, &w);

	}



	/*

	 * We need to create a child device explicitly from here to