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PCI device parsing complete?

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This commit is contained in:
Jackson Netherwood-Imig
2026-03-03 15:25:33 -08:00
parent e51569c9db
commit d5db200d07
3 changed files with 176 additions and 61 deletions
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example.zig
+5
View File
@@ -5,6 +5,11 @@ pub fn main(init: std.process.Init) !void {
const io = init.io;
const gpa = init.gpa;
const devid = drm.makeDev(226, 128);
const device = try drm.Device.getFromDevId(io, gpa, devid, .{});
std.log.info("Device node path: {s}.", .{device.nodePath()});
const card = try drm.Card.openAuto(io);
defer card.close(io);
const res = try card.getModesettingResources(gpa);
src/Device.zig
+168 -58
View File
@@ -2,17 +2,12 @@ const std = @import("std");
const drm = @import("drm.zig");
const sys = @import("sys.zig");
const log = std.log.scoped(.drm);
const node_max = 3;
const path_max = std.os.linux.PATH_MAX;
const Device = @This();
nodes: struct {
primary: ?[drm.max_node_name]u8,
/// Deprecated
control: ?[drm.max_node_name]u8,
render: ?[drm.max_node_name]u8,
},
node_type: NodeType,
node_path_buf: [drm.max_node_name:0]u8,
bus_info: union(BusType) {
pci: PciBusInfo,
usb: UsbBusInfo,
@@ -21,7 +16,7 @@ bus_info: union(BusType) {
faux: FauxBusInfo,
virtio: void,
},
device_info: union(BusType) {
device_info: ?union(BusType) {
pci: PciDeviceInfo,
usb: UsbDeviceInfo,
platform: PlatformDeviceInfo,
@@ -30,11 +25,15 @@ device_info: union(BusType) {
virtio: void,
},
pub fn nodePath(self: *const Device) []const u8 {
return std.mem.sliceTo(&self.node_path_buf, 0);
}
pub const Flags = packed struct {
get_pci_revision: bool = false,
};
pub fn getFromDevId(io: std.Io, devid: std.posix.dev_t, flags: Flags) !Device {
pub fn getFromDevId(io: std.Io, gpa: std.mem.Allocator, devid: std.posix.dev_t, flags: Flags) !Device {
var local_devices: [drm.max_nodes]Device = undefined;
const major = drm.devMajor(devid);
@@ -43,15 +42,15 @@ pub fn getFromDevId(io: std.Io, devid: std.posix.dev_t, flags: Flags) !Device {
if (!drm.nodeIsDrm(io, major, minor))
return error.NotDrmDevice;
const subsystem_type = try drm.parseSubsystemType(io, major, minor);
const subsystem_type = try parseSubsystemType(io, major, minor);
const sysdir = try std.Io.Dir.openDirAbsolute(io, drm.dir_name, .{ .iterate = true });
defer sysdir.close(io);
var it = sysdir.iterate();
const i: usize = 0;
while (try it.next(io)) |entry| {
const dev = processDevice(entry.name, subsystem_type, true, flags) catch continue;
var i: usize = 0;
while (try it.next(io)) |entry| if (entry.kind == .character_device) {
const dev = processDevice(io, gpa, entry.name, subsystem_type, true, flags) catch continue;
if (i >= drm.max_nodes) {
log.err(
@@ -63,7 +62,7 @@ pub fn getFromDevId(io: std.Io, devid: std.posix.dev_t, flags: Flags) !Device {
local_devices[i] = dev;
i += 1;
}
};
return for (local_devices[0..i]) |dev| {
if (hasRdev(dev, devid)) break dev;
@@ -132,7 +131,7 @@ pub const FauxBusInfo = struct {
};
pub fn parseSubsystemType(io: std.Io, major: u32, minor: u32) !Device.BusType {
var path_buf: [std.os.linux.PATH_MAX]u8 = undefined;
var path_buf: [path_max]u8 = undefined;
var path = std.ArrayList(u8).initBuffer(&path_buf);
path.printAssumeCapacity("/sys/dev/char/{d}:{d}/device", .{ major, minor });
@@ -156,10 +155,10 @@ fn getSubsystemType(io: std.Io, device_path: []const u8) !Device.BusType {
.{ .name = "/faux", .bus_type = .faux },
};
var path_buf: [std.os.linux.PATH_MAX]u8 = undefined;
var path_buf: [path_max]u8 = undefined;
const path = std.fmt.bufPrint(&path_buf, "{s}/subsystem", .{device_path}) catch unreachable;
var link_buf: [std.os.linux.PATH_MAX]u8 = undefined;
var link_buf: [path_max]u8 = undefined;
const link_len = try std.Io.Dir.cwd().readLink(io, path, &link_buf);
const link = link_buf[0..link_len];
@@ -177,39 +176,39 @@ pub const NodeType = enum {
/// Deprecated
control,
render,
_max,
pub const max = 3;
};
fn processDevice(
io: std.Io,
gpa: std.mem.Allocator,
name: []const u8,
required_subsystem_type: sys.BusType,
required_subsystem_type: BusType,
fetch_devinfo: bool,
flags: Flags,
) !Device {
const max_node_length = std.mem.alignForward(usize, drm.max_node_name, @sizeOf(usize));
const node_type = try getNodeType(name);
var path_buf: [std.os.linux.PATH_MAX]u8 = undefined;
var path_buf: [path_max]u8 = undefined;
const node = std.fmt.bufPrint(&path_buf, "{s}/{s}", .{ drm.dir_name, name }) catch unreachable;
if (node.len + 1 > max_node_length)
return error.NodePathTooLong;
const stat = try statx(node);
const major = stat.rdev_major;
const minor = stat.rdev_minor;
if (!drm.nodeIsDrm(io, stat.rdev_major, stat.rdev_minor) || !std.os.linux.S.ISCHR(stat.mode))
if (!drm.nodeIsDrm(io, stat.rdev_major, stat.rdev_minor) or !std.os.linux.S.ISCHR(stat.mode))
return error.InvalidDevice;
const subsystem_type = try drm.parseSubsystemType(io, stat.rdev_major, stat.rdev_minor);
const subsystem_type = try parseSubsystemType(io, stat.rdev_major, stat.rdev_minor);
if (subsystem_type != required_subsystem_type)
return error.IncorrectSubsystemType;
_ = fetch_devinfo;
_ = flags;
_ = node_type;
return switch (subsystem_type) {
.pci, .virtio => error.PciUnimplemented,
.pci, .virtio => try processPciDevice(io, gpa, node, node_type, major, minor, fetch_devinfo, flags),
.usb => error.UsbInimplemented,
.platform => error.PlatformUnimplemented,
.host1x => error.Host1xUnimplemented,
@@ -218,61 +217,172 @@ fn processDevice(
}
fn processPciDevice(
node: []const u8,
node_type: drm.NodeType,
io: std.Io,
gpa: std.mem.Allocator,
node_path: []const u8,
node_type: NodeType,
major: u32,
minor: u32,
fetch_devinfo: bool,
flags: Flags,
) !*Device {
) !Device {
var device = Device{
.nodes = .{ .primary = null, .control = null, .render = null },
.bus_info = undefined,
.device_info = undefined,
.node_type = node_type,
.node_path_buf = @splat(0),
.bus_info = .{ .pci = try parsePciBusInfo(io, gpa, major, minor) },
.device_info = if (fetch_devinfo) .{ .pci = try parsePciDeviceInfo(io, major, minor, flags) } else null,
};
_ = &device;
@memcpy(device.node_path_buf[0..node_path.len], node_path);
return device;
}
fn parsePciBusInfo(major: u32, minor: u32) !PciBusInfo {
const pci_path = try getPciPath(major, minor);
fn parsePciBusInfo(io: std.Io, gpa: std.mem.Allocator, major: u32, minor: u32) !PciBusInfo {
var pci_path_buf: [path_max]u8 = undefined;
const pci_path = try getPciPath(io, &pci_path_buf, major, minor);
const value = try sysfsUeventGet(&pci_path, "PCI_SLOT_NAME");
const value = try sysfsUeventGet(io, gpa, pci_path, "PCI_SLOT_NAME", .{});
defer gpa.free(value);
const format = "{x:4}:{x:2}:{x:2}.{d:1}";
const domain = try std.fmt.parseInt(u16, value[0..4], 16);
const bus = try std.fmt.parseInt(u8, value[5..7], 16);
const dev = try std.fmt.parseInt(u8, value[8..10], 16);
const func = try std.fmt.parseInt(u8, value[11..12], 16);
return PciBusInfo{
.domain = 0,
.bus = 0,
.dev = 0,
.func = 0,
.domain = domain,
.bus = bus,
.dev = dev,
.func = func,
};
}
fn parsePciDeviceInfo(io: std.Io, major: u32, minor: u32, flags: Flags) !PciDeviceInfo {
return if (!flags.get_pci_revision)
parseSeparateSysfsFiles(io, major, minor, true)
else
parseSeparateSysfsFiles(io, major, minor, false) catch
parseConfigSysfsFile(io, major, minor);
}
fn getPciPath(io: std.Io, buf: []u8, major: u32, minor: u32) ![]const u8 {
var path_buf: [path_max]u8 = undefined;
const path = try std.fmt.bufPrint(&path_buf, "/sys/dev/char/{}:{}/device", .{ major, minor });
const len = try std.Io.Dir.realPathFileAbsolute(io, path, buf);
const real_path = buf[0..len];
if (std.mem.endsWith(u8, real_path, "/virtio")) return buf[0 .. len - 7];
return real_path;
}
fn sysfsUeventGet(
io: std.Io,
gpa: std.mem.Allocator,
path: []const u8,
comptime format: []const u8,
args: anytype,
) ![]const u8 {
const key = try std.fmt.allocPrint(gpa, format, args);
defer gpa.free(key);
var filename_buf: [path_max]u8 = undefined;
const filename = try std.fmt.bufPrint(&filename_buf, "{s}/uevent", .{path});
const file = try std.Io.Dir.openFileAbsolute(io, filename, .{});
defer file.close(io);
var reader = file.reader(io, &.{});
const content = try reader.interface.allocRemaining(gpa, .unlimited);
defer gpa.free(content);
var it = std.mem.tokenizeScalar(u8, content, '\n');
while (it.next()) |line| {
if (std.mem.eql(u8, line[0..key.len], key) and line[key.len] == '=') {
return gpa.dupe(u8, line[key.len + 1 ..]);
}
}
return error.KeyNotFound;
}
fn parseSeparateSysfsFiles(
io: std.Io,
major: u32,
minor: u32,
ignore_revision: bool,
) !PciDeviceInfo {
const attrs = [_][]const u8{
"revision",
"vendor",
"device",
"subsystem_vendor",
"subsystem_device",
};
var pci_path_buf: [path_max]u8 = undefined;
const pci_path = try getPciPath(io, &pci_path_buf, major, minor);
const start: usize = if (ignore_revision) 1 else 0;
var data: [attrs.len]u16 = undefined;
for (attrs[start..], data[start..]) |attr, *value| {
var path_buf: [path_max]u8 = undefined;
const path = try std.fmt.bufPrint(&path_buf, "{s}/{s}", .{ pci_path, attr });
const file = try std.Io.Dir.openFileAbsolute(io, path, .{});
defer file.close(io);
var value_buf: [16]u8 = undefined;
const len = try file.readStreaming(io, &.{&value_buf}) - 1;
value.* = try std.fmt.parseInt(u16, value_buf[0..len], 0);
}
return PciDeviceInfo{
.revision_id = if (ignore_revision) 0xff else @intCast(data[0] & 0xff),
.vendor_id = data[1] & 0xffff,
.device_id = data[2] & 0xffff,
.subvendor_id = data[3] & 0xffff,
.subdevice_id = data[4] & 0xffff,
};
}
fn parseConfigSysfsFile(io: std.Io, major: u32, minor: u32) !PciDeviceInfo {
var pci_path_buf: [path_max]u8 = undefined;
const pci_path = try getPciPath(io, &pci_path_buf, major, minor);
var path_buf: [path_max]u8 = undefined;
const path = try std.fmt.bufPrint(&path_buf, "{s}/config", .{pci_path});
const file = try std.Io.Dir.openFileAbsolute(io, path, .{});
defer file.close(io);
var config: [64]u8 = undefined;
_ = try file.readStreaming(io, &.{&config});
return PciDeviceInfo{
.vendor_id = config[0] | @as(u16, config[1]) << 8,
.device_id = config[2] | @as(u16, config[3]) << 8,
.revision_id = config[8],
.subvendor_id = config[44] | @as(u16, config[45]) << 8,
.subdevice_id = config[46] | @as(u16, config[47]) << 8,
};
}
fn hasRdev(dev: Device, rdev: std.posix.dev_t) bool {
const node_fields = @typeInfo(@FieldType(Device, "available_nodes")).@"struct".fields;
inline for (node_fields, dev.nodes) |field, node| {
if (@field(dev.available_nodes, field.name)) {
const stat = statx(node) catch continue;
if (drm.makeDev(stat.rdev_major, stat.rdev_minor) == rdev) return true;
}
}
return false;
const stat = statx(dev.nodePath()) catch return false;
return drm.makeDev(stat.rdev_major, stat.rdev_minor) == rdev;
}
fn getNodeType(name: []const u8) !drm.NodeType {
if (std.mem.eql(u8, name, drm.primary_minor_name)) return .primary;
if (std.mem.eql(u8, name, drm.control_minor_name)) return .control;
if (std.mem.eql(u8, name, drm.render_minor_name)) return .render;
fn getNodeType(name: []const u8) !NodeType {
if (std.mem.eql(u8, name[0..drm.primary_minor_name.len], drm.primary_minor_name)) return .primary;
if (std.mem.eql(u8, name[0..drm.control_minor_name.len], drm.control_minor_name)) return .control;
if (std.mem.eql(u8, name[0..drm.render_minor_name.len], drm.render_minor_name)) return .render;
return error.InvalidName;
}
fn statx(path: []const u8) !std.os.linux.Statx {
const posix_path = std.posix.toPosixPath(path);
const posix_path = try std.posix.toPosixPath(path);
var stat_buf: std.os.linux.Statx = undefined;
const rc = std.os.linux.statx(std.os.linux.AT.FDCWD, &posix_path, 0, .{}, &stat_buf);
return switch (std.posix.errno(rc)) {
src/drm.zig
+3 -3
View File
@@ -22,17 +22,17 @@ pub const max_node_name = dir_name.len + @max(
render_minor_name.len,
) + 3;
pub fn devMajor(dev: dev_t) u32 {
pub inline fn devMajor(dev: dev_t) u32 {
return @intCast(((dev & @as(dev_t, 0x00000000000fff00)) >> 8) |
((dev & @as(dev_t, 0xfffff00000000000)) >> 32));
}
pub fn devMinor(dev: dev_t) u32 {
pub inline fn devMinor(dev: dev_t) u32 {
return @intCast(((dev & @as(dev_t, 0x00000000000000ff)) >> 0) |
((dev & @as(dev_t, 0x00000ffffff00000)) >> 12));
}
pub fn makeDev(major: u32, minor: u32) dev_t {
pub inline fn makeDev(major: u32, minor: u32) dev_t {
return (@as(dev_t, major & 0x00000fff) << 8) |
(@as(dev_t, major & 0xfffff000) << 32) |
(@as(dev_t, minor & 0x000000ff) << 0) |