On 11/09/2012 06:48 PM, Stepan Moskovchenko wrote:
> Use the cell-index property to construct names for platform
> devices, falling back on the existing scheme of using the
> device register address if cell-index is not specified.
>
> The cell-index property is a more useful device identifier,
> especially in systems containing several numbered instances
> of a particular hardware block, since it more easily
> illustrates how devices relate to each other.
>
> Additionally, userspace software may rely on the classic
> <name>.<id> naming scheme to access device attributes in
> sysfs, without having to know the physical addresses of
> that device on every platform the userspace software may
> support. Using cell-index for device naming allows the
> device addresses to be hidden from userspace and to be
> exposed by logical device number without having to rely on
> auxdata to perform name overrides. This allows userspace to
> make assumptions about which sysfs nodes map to which
> logical instance of a specific hardware block.
>
> Signed-off-by: Stepan Moskovchenko <stepanm@xxxxxxxxxxxxxx>
> ---
> I had also considered using something like the linux,label property to allow
> custom names for platform devices without resorting to auxdata, but the
> cell-index approach seems more in line with what cell-index was intended for
> and with what the pre-DT platform device naming scheme used to be. Please let
> me know if you think there is a better way to accomplish this.
>
> This is just being sent out as an RFC for now. If there are no objections, I
> will send this out as an official patch, along with (or combined with) a patch
> to fix up the device names in things like clock tables of any affected
> platforms.
cell-index is basically deprecated. This has been discussed multiple
times in the past. You can use auxdata if you really need to have the
old name.
Rob
>
> drivers/of/platform.c | 13 ++++++++++++-
> 1 files changed, 12 insertions(+), 1 deletions(-)
>
> diff --git a/drivers/of/platform.c b/drivers/of/platform.c
> index 343ad29..472e374 100644
> --- a/drivers/of/platform.c
> +++ b/drivers/of/platform.c
> @@ -77,8 +77,9 @@ void of_device_make_bus_id(struct device *dev)
> static atomic_t bus_no_reg_magic;
> struct device_node *node = dev->of_node;
> const u32 *reg;
> + u32 cell_index;
> u64 addr;
> - int magic;
> + int magic, ret;
>
> #ifdef CONFIG_PPC_DCR
> /*
> @@ -101,6 +102,16 @@ void of_device_make_bus_id(struct device *dev)
> #endif /* CONFIG_PPC_DCR */
>
> /*
> + * For devices with a specified cell-index, use the traditional
> + * naming scheme of <name>.<id>
> + */
> + ret = of_property_read_u32(node, "cell-index", &cell_index);
> + if (ret == 0) {
> + dev_set_name(dev, "%s.%d", node->name, cell_index);
> + return;
> + }
> +
> + /*
> * For MMIO, get the physical address
> */
> reg = of_get_property(node, "reg", NULL);
> --
> The Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
> hosted by The Linux Foundation
>
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