[PATCH RFC 0/5] Hybrid approach for DT schema checking

[Tomasz Figa]

This series adds a proof of concept framework to implement schema checker
using a combined C and DTSS based approach. Several example bindings are
also implemented using C and DTSS[1].

Complex and generic bindings can be implemented directly in C and then
instantiated from simple device-specific bindings using DTS-like DTSS
language.

A quick description of C part:

A new check is registered in dtc checks framework to perform schema checking
of each node. Checking is done by searching specified schema set for matching
schemas (by compatible, device_type or absolute path) and applying matched
schemas to the node.

Schemas for complex generic bindings (such as interrupts, gpios, clocks, i2c,
mmio-bus, etc.) can be implemented directly in C and instantiated from DTSS
schemas of particular devices. An example C schema may look like:

static void generic_checkfn_xxx_yyy(const struct generic_schema *schema,
				    struct node *root, struct node *node,
				    struct node *params, bool required)
{
	/*
	 * Get necessary schema arguments from DTSS schema by looking
	 * at properties of @params node.
	 * 
	 * Check whether @node node matches the schema.
	 *
	 * The @required argument may be used to check whether some error
	 * conditions should be ignored (e.g. unspecified interrupt).
	 */
}
GENERIC_SCHEMA("xxx-yyy", xxx_yyy);

A quick description of DTSS part:

* DTSS is a DTS-like language for specification of simple bindings, e.g.
  bindings of particular devices. The basic syntax is very similar to DTS,
  with main elements being nodes and properties. At root level a series of
  nodes should be specified representing particular bindings:

	/dtss-v1/;

	binding1 {
		/* Definition of binding 1 */
	};

	binding2 {
		/* Definition of binding 2 */
	};

* Matching key for each binding can be specified using /match/ keyword:

	root-node {
		/match/ path = "/";
	};

	wlf,wm8903 {
		/match/ compatible = "wlf,wm8903";
	};

	pci-bus {
		/match/ device_type = "memory";
	};

  Currently supported matches: path, compatible, device_type.

* Bindings can be specified either by listing properties they require
  (or can use) directly or by instantiating generic C-based bindings.

	binding {
		required-property;

		/optional/ optional-property;

		/require/ required-generic-schema;

		/use/ optional-generic-schema {
			schema-argument = <1>;
		};
	};

  Generic schemas are implemented in C, as described above, and can use
  arguments specified in DTSS as properties. /require/ calls the schema with
  required=true, while /use/ with required=false.

This is based on Stephen Warren's C based DT schema checker proof of
concept patch adding C-based validation[2].

TODO:
 - specification of subnodes directly from DTSS,
 - specification of simple property values from DTSS (cells, strings,
   phandles),
 - reporting of unrecognized properties,
 - probably many more...

[1] Device Tree Schema Source
[2] http://thread.gmane.org/gmane.linux.ports.arm.kernel/275896

Tomasz Figa (5):
  dtc: Add helpers for various message levels
  dtc: livetree: Add more tree parsing helpers
  Another try of DT schema checker using hybrid C and DTSS based
    approach
  Add sample C-based generic bindings
  Add sample DTS and DTSS schema

 Makefile                                  |   2 +-
 Makefile.dtc                              |  10 +-
 checks.c                                  |  15 +
 dtc.c                                     |  17 +-
 dtc.h                                     |  57 ++++
 dtss-lexer.l                              | 291 +++++++++++++++++++
 dtss-parser.y                             | 341 ++++++++++++++++++++++
 livetree.c                                | 230 +++++++++++++++
 sample.dts                                |  70 +++++
 schema.dtss                               |  86 ++++++
 schemas/clock/clock.c                     |  77 +++++
 schemas/gpio/gpio.c                       |  93 ++++++
 schemas/i2c/i2c.c                         |  42 +++
 schemas/interrupt-controller/interrupts.c | 452 ++++++++++++++++++++++++++++++
 schemas/mmio-bus.c                        |  97 +++++++
 schemas/schema.c                          | 311 ++++++++++++++++++++
 schemas/schema.h                          |  89 ++++++
 srcpos.h                                  |   2 +
 treesource.c                              |  22 ++
 19 files changed, 2300 insertions(+), 4 deletions(-)
 create mode 100644 dtss-lexer.l
 create mode 100644 dtss-parser.y
 create mode 100644 sample.dts
 create mode 100644 schema.dtss
 create mode 100644 schemas/clock/clock.c
 create mode 100644 schemas/gpio/gpio.c
 create mode 100644 schemas/i2c/i2c.c
 create mode 100644 schemas/interrupt-controller/interrupts.c
 create mode 100644 schemas/mmio-bus.c
 create mode 100644 schemas/schema.c
 create mode 100644 schemas/schema.h

-- 
1.8.5.2