[PATCH v2 09/38] memory: mvebu-devbus: add a devbus,keep-config property

[sebastian.hesselbarth@gmail.com (Sebastian Hesselbarth)]

On 04/22/2014 11:26 PM, Thomas Petazzoni wrote:
> 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: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>

> ---
>   .../bindings/memory-controllers/mvebu-devbus.txt   | 29 ++++++++++++++--------
>   drivers/memory/mvebu-devbus.c                      | 20 ++++++++-------
>   2 files changed, 29 insertions(+), 20 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt b/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt
> index 55adde2..1ee3bc0 100644
> --- a/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt
> +++ b/Documentation/devicetree/bindings/memory-controllers/mvebu-devbus.txt
> @@ -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
> diff --git a/drivers/memory/mvebu-devbus.c b/drivers/memory/mvebu-devbus.c
> index c8f3dad..ff7138f 100644
> --- a/drivers/memory/mvebu-devbus.c
> +++ b/drivers/memory/mvebu-devbus.c
> @@ -310,16 +310,18 @@ static int mvebu_devbus_probe(struct platform_device *pdev)
>   	dev_dbg(devbus->dev, "Setting timing parameter, tick is %lu ps\n",
>   		devbus->tick_ps);
>
> -	/* Read the Device Tree node */
> -	err = devbus_get_timing_params(devbus, node, &r, &w);
> -	if (err < 0)
> -		return err;
> +	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)
> +			return err;
>
> -	/* Set the new timing parameters */
> -	if (of_device_is_compatible(node, "marvell,orion-devbus"))
> -		devbus_orion_set_timing_params(devbus, node, &r, &w);
> -	else
> -		devbus_armada_set_timing_params(devbus, node, &r, &w);
> +		/* Set the new timing parameters */
> +		if (of_device_is_compatible(node, "marvell,orion-devbus"))
> +			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
>