NAME

ofw_bus_is_compatible ofw_bus_is_compatible_strict ofw_bus_node_is_compatible ofw_bus_search_compatible — check device tree nodes for compatibility with drivers

SYNOPSIS

#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>

int
ofw_bus_is_compatible(device_t dev, const char *compatstr);

int
ofw_bus_is_compatible_strict(device_t dev, const char *compatstr);

int
ofw_bus_node_is_compatible(phandle_t node, const char *compatstr);

const struct ofw_compat_data *
ofw_bus_search_compatible(device_t dev, const struct ofw_compat_data *compat);

DESCRIPTION

The "compatible" property of the device tree node is used to identify the type of the device the node represents. The property is a list of one or more strings that represent hardware types the device is compatible with. The common format for such strings is "vendor,hardware" where "vendor" is an abbreviated name of the manufacturer and "hardware" is a device identifier, for instance, "fsl" for "Freescale" and "imx6ul-i2c" for the I2C controller. More than one string is required for compatibility with older revisions of the driver. If hardware revision B is backward compatible with revision A device tree node can signal this compatibility by providing both "vndr,hrdwrA" and "vndr,hrdwrB" strings in the "compatibile" property value. This way older driver can use features available only in revision A, and the new version of the driver can take advantage of revision B feature set.

ofw_bus_is_compatible() returns 1 if the compatstr value occurs in the "compatible" property list of the device tree node associated with the device dev, and 0 otherwise.

ofw_bus_is_compatible_strict() return 1 if the "compatible" property of the device tree node associated with the device dev consists of only one string and this string is equal to compatstr, and 0 otherwise.

ofw_bus_node_is_compatible() returns 1 if the compatstr value occurs in the "compatible" property list of the device tree node node, and 0 otherwise.

ofw_bus_search_compatible() returns pointer to the first entry of the compat table whose ocd_str field occurs in "compatible" property of the device tree node associated with the device dev. The compat table is an array of struct ofw_compat_data elements defined as follows:

struct ofw_compat_data {
	const char *ocd_str;
	uintptr_t  ocd_data;
};

EXAMPLES

static struct ofw_compat_data compat_data[] = {
	{"arm,hrdwrA",		FEATURE_A},
	{"arm,hrdwrB",		FEATURE_A | FEATURE_B},
	{NULL,			0}
};

static int
hrdwr_probe(device_t dev)
{
	...
	if (!ofw_bus_search_compatible(dev, compat_data)->ocd_data)
		return (ENXIO);
	...
}

static int
hrdwr_attach(device_t dev)
{
	...
	sc = device_get_softc(dev);
	sc->sc_features = ofw_bus_search_compatible(dev, compat_data)->ocd_data;
	...
}

SEE ALSO

ofw_bus_find_compatible(9)

AUTHORS

This manual page was written by Oleksandr Tymoshenko.