[PATCH v2 09/38] memory: mvebu-devbus: add a devbus,keep-config property
Sebastian Hesselbarth
sebastian.hesselbarth at gmail.com
Wed Apr 23 04:18:05 PDT 2014
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 at free-electrons.com>
Acked-by: Sebastian Hesselbarth <sebastian.hesselbarth at 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
>
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