On Fri, Oct 31, 2014 at 6:59 AM, Gilad Avidov <gavidov@xxxxxxxxxxxxxx> wrote:
>
> Device-Tree compact API
> ------------------------
>
> Common code seen in driver’s probe reads device tree values and handling
> erroneous return codes from all those of_property_read_xxx() APIs. This
> common code is factored out by the of_property_map module which allows
> driver’s probe to replace that (often lengthy) code with a concise table:
>
> struct of_prop_map map[] = {
> {"i2c", &dev->id, OF_REQ, OF_ID, -1},
> {"qcom,clk-freq-out", &dev->clk_freq_out, OF_REQ, OF_U32, 0},
> {"qcom,clk-freq-in", &dev->clk_freq_in, OF_REQ, OF_U32, 0},
> {"qcom,disable-dma", &dev->disable_dma, OF_OPT, OF_BOOL, 0},
> {"qcom,master-id", &dev->mstr_id, OF_SGST, OF_U32, 0},
> {NULL, NULL, 0, 0, 0},
> };
>
> Then call populate to read the values into the device’s variables:
>
> ret = of_prop_populate(dev, dev->of_node, map);
Interesting idea. The main concern I have with this is there has been
on-going discussions about how to generalize property handling across
DT and ACPI to make drivers more agnostic, so I'm copying a few folks
involved in that. That may be a bit orthogonal to what this is doing,
but we may want some coordination here.
BTW, there is little point to a 0/1 email. All this info should be in
the patch either in commit msg or documentation as part of the patch.
Rob
> An equivalent code snippet using the traditional of_property_read_XXXX()
> API. Note that the equivalent is longer and more difficult to follow and
> debug:
>
> /* optional property */
> dev->disable_dma = of_property_read_bool(node, "qcom,disable-dma");
>
> ret = of_property_read_u32(dev->node, "qcom,clk-freq-out", &dev->clk_freq_out);
> if (ret) {
> dev_err(dev, "error: missing 'qcom,clk-freq-out' DT property\n");
> if (!err)
> err = ret;
> }
>
> ret = of_property_read_u32(dev->node, "qcom,clk-freq-in", &dev->clk_freq_in);
> if (ret) {
> dev_err(dev, "error: missing 'qcom,clk-freq-in' DT property\n");
> if (!err)
> err = ret;
> }
>
> /* suggested property */
> ret = of_property_read_u32(dev->node, "qcom,master-id", &dev->mstr_id);
> if (ret && !err)
> err = ret;
>
>
> ret = of_alias_get_id(dev->node, "i2c");
> if (ret < 0) {
> dev_err(dev, "error: missing '"i2c"' DT property\n");
> if (!err)
> err = ret;
> } else {
> dev->id = ret;
> }
>
>
> The Device-Tree node and alias which are read by the above code snippets:
>
> aliases {
> i2c0 = &i2c_0; /* I2C0 controller device */
> };
>
> i2c_0: i2c@78b6000 { /* BLSP1 QUP2 */
> compatible = "qcom,i2c-msm-v2";
> reg-names = "qup_phys_addr", "bam_phys_addr";
> reg = <0x78b6000 0x600>,
> <0x7884000 0x23000>;
> qcom,clk-freq-out = <100000>;
> qcom,clk-freq-in = <19200000>;
> qcom,disable-dma;
> qcom,master-id = <86>;
> };
>
>
> Gilad Avidov (1):
> of_propery_map: compact interface for Device-Tree
>
> Documentation/devicetree/of_property_map.txt | 76 ++++++++++++++++++++++
> drivers/of/Makefile | 2 +-
> drivers/of/of_property_map.c | 88 ++++++++++++++++++++++++++
> include/linux/of_property_map.h | 74 ++++++++++++++++++++++
> 4 files changed, 239 insertions(+), 1 deletion(-)
> create mode 100644 Documentation/devicetree/of_property_map.txt
> create mode 100644 drivers/of/of_property_map.c
> create mode 100644 include/linux/of_property_map.h
>
> --
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
> hosted by The Linux Foundation
>
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