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authorAndy Fleming <afleming@freescale.com>2008-04-18 18:29:54 -0400
committerJeff Garzik <jgarzik@redhat.com>2008-04-25 02:08:52 -0400
commitf62220d3a9ccb879c3f90f845ae57b724b7bbb62 (patch)
tree72697d5d0b7bfdebaf0fd74bea07212c9820a6df /Documentation/networking
parent8ec7226a93dcd4a314e2387d1033aef01145061b (diff)
phylib: Add support for board-level PHY fixups
Sometimes the specific interaction between the platform and the PHY requires special handling. For instance, to change where the PHY's clock input is, or to add a delay to account for latency issues in the data path. We add a mechanism for registering a callback with the PHY Lib to be called on matching PHYs when they are brought up, or reset. Signed-off-by: Andy Fleming <afleming@freescale.com> Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Diffstat (limited to 'Documentation/networking')
-rw-r--r--Documentation/networking/phy.txt38
1 files changed, 37 insertions, 1 deletions
diff --git a/Documentation/networking/phy.txt b/Documentation/networking/phy.txt
index 0bc95eab1512..8df6a7b0e66c 100644
--- a/Documentation/networking/phy.txt
+++ b/Documentation/networking/phy.txt
@@ -1,7 +1,7 @@
1 1
2------- 2-------
3PHY Abstraction Layer 3PHY Abstraction Layer
4(Updated 2006-11-30) 4(Updated 2008-04-08)
5 5
6Purpose 6Purpose
7 7
@@ -291,3 +291,39 @@ Writing a PHY driver
291 Feel free to look at the Marvell, Cicada, and Davicom drivers in 291 Feel free to look at the Marvell, Cicada, and Davicom drivers in
292 drivers/net/phy/ for examples (the lxt and qsemi drivers have 292 drivers/net/phy/ for examples (the lxt and qsemi drivers have
293 not been tested as of this writing) 293 not been tested as of this writing)
294
295Board Fixups
296
297 Sometimes the specific interaction between the platform and the PHY requires
298 special handling. For instance, to change where the PHY's clock input is,
299 or to add a delay to account for latency issues in the data path. In order
300 to support such contingencies, the PHY Layer allows platform code to register
301 fixups to be run when the PHY is brought up (or subsequently reset).
302
303 When the PHY Layer brings up a PHY it checks to see if there are any fixups
304 registered for it, matching based on UID (contained in the PHY device's phy_id
305 field) and the bus identifier (contained in phydev->dev.bus_id). Both must
306 match, however two constants, PHY_ANY_ID and PHY_ANY_UID, are provided as
307 wildcards for the bus ID and UID, respectively.
308
309 When a match is found, the PHY layer will invoke the run function associated
310 with the fixup. This function is passed a pointer to the phy_device of
311 interest. It should therefore only operate on that PHY.
312
313 The platform code can either register the fixup using phy_register_fixup():
314
315 int phy_register_fixup(const char *phy_id,
316 u32 phy_uid, u32 phy_uid_mask,
317 int (*run)(struct phy_device *));
318
319 Or using one of the two stubs, phy_register_fixup_for_uid() and
320 phy_register_fixup_for_id():
321
322 int phy_register_fixup_for_uid(u32 phy_uid, u32 phy_uid_mask,
323 int (*run)(struct phy_device *));
324 int phy_register_fixup_for_id(const char *phy_id,
325 int (*run)(struct phy_device *));
326
327 The stubs set one of the two matching criteria, and set the other one to
328 match anything.
329