Add a simple-framebuffer vt driver

[andrew]

Summary

This allows us to support this hardware and, in the future, use clocks
so they are enabled past the initial kernel boot process.

[manu]

I don't think it make much sense to commit that without all formats supported and clocks, efifb should be good enough instead. (and yes I know that it's not on the mac blah that you're working on :P )

sys/dev/vt/hw/simplefb/simplefb.c

91

I only see a8r8g8b8 and r5g6b5 as supported format currently : https://cgit.freebsd.org/src/tree/sys/contrib/device-tree/Bindings/display/simple-framebuffer.yaml#n82

[andrew]

I can easily add more formats, although can't test the clocks as I don't have hardware that has the clocks property.

sys/dev/vt/hw/simplefb/simplefb.c

6

@emaste Can I drop this? It's in all the vt drivers where the Foundation has a copyright statement.

91

Most of them are missing from the bindings. This seems to be a full list of the currently supported formats: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/linux/platform_data/simplefb.h?id=d665ea6ea86c785760ee4bad4543dab3267ad074#n16

I can easily add the other formats. It looks like a8r8g8b8, r5g6b5, and r8g8b8 are used in the in-tree dts files. Many of the simple-framebuffer nodes lack a format so I guess the firmware fills this property in.

[manu]

In D30103#676103, @andrew wrote:

I can easily add more formats, although can't test the clocks as I don't have hardware that has the clocks property.

I'll handle the clock part if you want but it's something like
clk_t clk;
int err;
for (int idx = 0; ; idx++) {
err = clk_get_by_ofw_index(dev, 0, idx, &clk);
if (err == 0)

clk_enable(clk);

else

break;

}

sys/dev/vt/hw/simplefb/simplefb.c

91

I'll boot a few board this weekend to check if there is other format added by bootloader.

[andrew]

We don't have a device_t to use this early so would need to create a driver to attach to the same node later in the boot. One of the problems is it's a child of /chosen so doesn't get probed. For testing I created a chosen driver we could use that attaches to the chosen node and adds any children it finds.

[andrew]

Add more formats found in local dts files

[manu]

In D30103#676127, @andrew wrote:

We don't have a device_t to use this early so would need to create a driver to attach to the same node later in the boot. One of the problems is it's a child of /chosen so doesn't get probed. For testing I created a chosen driver we could use that attaches to the chosen node and adds any children it finds.

Mhm right, I'll have to think about how to do this properly ...

[emaste]

sys/dev/vt/hw/simplefb/simplefb.c

6

Yes all FreeBSD Foundation copyrights can have All rights reserved. removed. I did a pass over the tree before but did not get everything.

125

Hrm, this is what we're using everywhere I suppose :(

[kevans]

sys/dev/vt/hw/simplefb/simplefb.c

87

I think, if I understand the notation correctly?

[kevans]

• Drop "all rights reserved", as per emaste 2021/01/05
• Correct red offset

[ray]

Looks good to me.
Thanks!

sys/dev/vt/hw/simplefb/simplefb.c

87

Yes. All I saw defined from higher to lower. So "b5" is lower 5 bits.

[emaste]

sys/dev/vt/hw/simplefb/simplefb.c

8–9

You could change this to "Portions of this software were..."