Den 13.05.2015 21:00, skrev Eric Anholt:
This gives us a function for making mailbox property channel requests
of the firmware, which is most notable in that it will let us get and
set clock rates.
Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
---
[...]
+/*
+ * Submits a single tag to the VPU firmware through the mailbox
+ * property interface.
+ *
+ * This is a convenience wrapper around
+ * rpi_firmware_property_list() to avoid some of the
+ * boilerplate in property calls.
+ */
+int rpi_firmware_property(struct device_node *of_node,
+ u32 tag, void *tag_data, size_t buf_size)
To use the firmware property functions, I need a DT node pointer.
Since Device Tree is dynamic now, should I fetch the firmware node
each time, or should I do that in probe and store the node pointer?
Device Tree:
firmware: firmware {
compatible = "raspberrypi,firmware";
};
thermal {
compatible = "brcm,bcm2835-thermal";
firmware = <&firmware>;
};
Rewritten (not tested) function from downstream bcm2835-thermal driver:
static int bcm2835_get_temp_or_max(struct thermal_zone_device *thermal_dev,
unsigned long *temp, unsigned tag_id)
{
struct device *dev = <get device somehow>;
struct device_node *np;
struct {
u32 id;
u32 val;
} tag_buf;
np = of_parse_phandle(dev->of_node, "firmware", 0);
if (!np)
return -EINVAL;
ret = rpi_firmware_property(np, tag_id, &tag_buf, sizeof(tag_buf));
if (ret)
return ret;
*temp = val;
return 0;
}
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