From nobody Mon Mar 3 16:57:00 2025 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4Z64jT2mR0z5pnMR; Mon, 03 Mar 2025 16:57:01 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R10" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4Z64jS5QRXz46C0; Mon, 03 Mar 2025 16:57:00 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1741021020; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=OeF2QLJYBCycuCU7plLW8V1/c0Db/iOTSafAEjZA04M=; b=K3ap9LsDWJnN6RGnJ+ICDAMUlg0g8k+IfwXKqr9AZzGr2klWmF14lBpWevYoYGW7p7Ip+z 3EIgnB+IYCH3aNVnGXVspWlicVHNpHfmCfWABWUJXWtkB2a1ChNW6zXp+KE3nxEpzwfpBs oViyOq9rCDtuLXZyavHT+k/RqU/CAbpe7TenEFMtX+qB4Oyjq285e3hLUSUybRjp8lawtp RKUlpo/MowprLnfJct/DOsyrPWChyJoAaZM5IXPtMEQFIx8jsyYLZWfacB4xu5z2yOXlvk Yp/aR6+aXje8sOPX4ZMn/QhEK8li6GZphqGyYKRZKEwPK+Py97HSryqg4YEEOw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1741021020; a=rsa-sha256; cv=none; b=Uv85seAvMPSQ0t0+QvHLzW2GN8STqObDvbgKTp6HcBFyAjqisS9MwUAQHfBbA1m7efdNCT JBKJk8jPxiUHhOoP69H60jDEej20duL1OeASU/mKSl2n4oCqpDGbpN/svT0JaCZJDfCyKC gHPVSJJ0ghcGGgcSy2SyzJO1u4/XfH1SqY2wV4MbJUjCImHI4ULjzuHo4zWbbKPkVCZnmg jtVGSSbwuNyFwyHFZukX1ScQRCbw1DZL0N2yzNFUu/o6WnPK7y8O4/w5nNbBK5lYbPfvBv uAhjMYVqn2AKQhqAe8ecvJLDTr5lIf8AQlS+rmpBXIjQCx9WKbXyFDqsNie9dw== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1741021020; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=OeF2QLJYBCycuCU7plLW8V1/c0Db/iOTSafAEjZA04M=; b=POj+0mqhdTQk9sEqRzg+HPuaX3i5IlXPqHAf4kdRifqXLEia3vjiRxxdaWD0lSJqUWt/5d J21r77Wir00FKMt6X7nyNsOo3XjAmZ9ntPe7Mr8rt9NVEznajuE8n77aKgSHMGaL4zWPUw AK7odusQ51bU2cOWRH0kTxeGWa1IpxatOQL9E4+EfsfpZ5pdMZajybth4aC09HOoaTlnU2 RnrpnORtxlWIXcqHE3YIMdJvdzmL9OS9LQj8OrTT7Ukt+/NTJibvVyRXb+dsDqLiAhs8Zz NldQ/0sjLdVfahwqysHsi/3ifFXi9ZZOKBzkV42zTAo2sjYZyk8zbSPKN4ltcA== Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4Z64jS4zjzzwtl; Mon, 03 Mar 2025 16:57:00 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.18.1/8.18.1) with ESMTP id 523Gv0Sg083767; Mon, 3 Mar 2025 16:57:00 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 523Gv0AF083764; Mon, 3 Mar 2025 16:57:00 GMT (envelope-from git) Date: Mon, 3 Mar 2025 16:57:00 GMT Message-Id: <202503031657.523Gv0AF083764@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: John Baldwin Subject: git: f1ef0525f34d - stable/14 - DEVICE_IDENTIFY.9: Modernize description and use cases List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: jhb X-Git-Repository: src X-Git-Refname: refs/heads/stable/14 X-Git-Reftype: branch X-Git-Commit: f1ef0525f34d5c21f330e60ff0366d38db509710 Auto-Submitted: auto-generated The branch stable/14 has been updated by jhb: URL: https://cgit.FreeBSD.org/src/commit/?id=f1ef0525f34d5c21f330e60ff0366d38db509710 commit f1ef0525f34d5c21f330e60ff0366d38db509710 Author: John Baldwin AuthorDate: 2025-01-09 20:20:16 +0000 Commit: John Baldwin CommitDate: 2025-03-03 16:56:20 +0000 DEVICE_IDENTIFY.9: Modernize description and use cases Mention adding devices based on firmware tables and software-only pseudo-devices as use cases for identify methods as those are more common than reading random I/O ports to identify a legacy ISA device. Describe how device_find_chid can be used to avoid duplicates. While here, explicitly note that devices added in identify methods typically use a fixed device name. Trim the cross-references a bit. Reviewed by: ziaee, imp Differential Revision: https://reviews.freebsd.org/D48367 (cherry picked from commit ccabc7c2e556ac0b14da9b682b706ccaf251c0fe) --- share/man/man9/DEVICE_IDENTIFY.9 | 52 +++++++++++++++++++--------------------- 1 file changed, 25 insertions(+), 27 deletions(-) diff --git a/share/man/man9/DEVICE_IDENTIFY.9 b/share/man/man9/DEVICE_IDENTIFY.9 index 4892e66eb214..9feb18f43f18 100644 --- a/share/man/man9/DEVICE_IDENTIFY.9 +++ b/share/man/man9/DEVICE_IDENTIFY.9 @@ -26,44 +26,46 @@ .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. .\" -.Dd January 15, 2017 +.Dd January 9, 2025 .Dt DEVICE_IDENTIFY 9 .Os .Sh NAME .Nm DEVICE_IDENTIFY -.Nd identify a device, register it +.Nd identify new child devices and register them .Sh SYNOPSIS .In sys/param.h .In sys/bus.h .Ft void .Fn DEVICE_IDENTIFY "driver_t *driver" "device_t parent" .Sh DESCRIPTION -The identify function for a device is only needed for devices on buses -that cannot identify their children independently, e.g.\& the ISA bus. -It is used to recognize the device (usually done by accessing non-ambiguous -registers in the hardware) and to tell the kernel about it and thus -creating a new device instance. +The identify method of a device driver is used to add devices that cannot be +enumerated by the standard method on a bus device. +Devices can be enumerated in various ways including accessing non-ambiguous +device registers and parsing firmware tables. +Software-only pseudo devices are also often enumerated via identify methods. .Pp +For each newly identified device, +a new device instance should be created by invoking the .Xr BUS_ADD_CHILD 9 -is used to register the device as a child of the bus. -The device's resources (such as IRQ and I/O ports) are registered -with the kernel by calling -.Fn bus_set_resource -for each resource (refer to +method. +If the identify method is able to discover other properties about the new +device, those should also be set. +For example, device resources should be added to the device by calling .Xr bus_set_resource 9 -for more information). +for each resource. .Pp -Since the device tree and the device driver tree are disjoint, the -.Fn DEVICE_IDENTIFY -routine needs to take this into account. -If you load and unload your device driver that has the identify -routine, the child node has the potential for adding the same node -multiple times unless specific measure are taken to preclude that -possibility. +An identify method might be invoked multiple times. +If a device driver is unloaded and loaded, +the identify method will be called a second time after being reloaded. +As a result, the identify method should avoid duplicate devices. +Devices added by identify methods typically use a fixed device name +in which case +.Xr device_find_child 9 +can be used to detect existing devices. .Sh EXAMPLES The following pseudo-code shows an example of a function that probes for a piece of hardware and registers it and its resource -(an I/O port) with the kernel. +(an I/O port) with the parent bus device. .Bd -literal void foo_identify(driver_t *driver, device_t parent) @@ -72,7 +74,7 @@ foo_identify(driver_t *driver, device_t parent) retrieve_device_information; if (devices matches one of your supported devices && - not already in device tree) { + device_get_child(parent, "foo", -1) == NULL) { child = BUS_ADD_CHILD(parent, 0, "foo", -1); bus_set_resource(child, SYS_RES_IOPORT, 0, FOO_IOADDR, 1); } @@ -82,11 +84,7 @@ foo_identify(driver_t *driver, device_t parent) .Xr BUS_ADD_CHILD 9 , .Xr bus_set_resource 9 , .Xr device 9 , -.Xr device_add_child 9 , -.Xr DEVICE_ATTACH 9 , -.Xr DEVICE_DETACH 9 , -.Xr DEVICE_PROBE 9 , -.Xr DEVICE_SHUTDOWN 9 +.Xr device_find_child 9 .Sh AUTHORS This manual page was written by .An Alexander Langer Aq Mt alex@FreeBSD.org .