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Date: Fri, 7 Apr 2017 11:30:37 +0300
From: Oleksandr Andrushchenko <andr2000@...il.com>
To: xen-devel@...ts.xenproject.org
Cc: joculator@...il.com, al1img@...il.com, vlad.babchuk@...il.com,
andrii.anisov@...il.com, olekstysh@...il.com,
konrad.wilk@...cle.com, lars.kurth@...rix.com,
julien.grall@....com, andr2000@...il.com, sstabellini@...nel.org,
linux-kernel@...r.kernel.org,
Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
Subject: [For Linux 1/4] xen/kbdif: update protocol description
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
The patch clarifies the protocol that is used by the PV keyboard
drivers.
Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
Reviewed-by: Stefano Stabellini <sstabellini@...nel.org>
Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@...m.com>
---
include/xen/interface/io/kbdif.h | 258 +++++++++++++++++++++++++++++++++++----
1 file changed, 231 insertions(+), 27 deletions(-)
diff --git a/include/xen/interface/io/kbdif.h b/include/xen/interface/io/kbdif.h
index 8066c7849fbe..e83eaddb20dc 100644
--- a/include/xen/interface/io/kbdif.h
+++ b/include/xen/interface/io/kbdif.h
@@ -26,43 +26,223 @@
#ifndef __XEN_PUBLIC_IO_KBDIF_H__
#define __XEN_PUBLIC_IO_KBDIF_H__
-/* In events (backend -> frontend) */
+/*
+ *****************************************************************************
+ * Feature and Parameter Negotiation
+ *****************************************************************************
+ *
+ * The two halves of a para-virtual driver utilize nodes within
+ * XenStore to communicate capabilities and to negotiate operating parameters.
+ * This section enumerates these nodes which reside in the respective front and
+ * backend portions of XenStore, following XenBus convention.
+ *
+ * All data in XenStore is stored as strings. Nodes specifying numeric
+ * values are encoded in decimal. Integer value ranges listed below are
+ * expressed as fixed sized integer types capable of storing the conversion
+ * of a properly formated node string, without loss of information.
+ *
+ *****************************************************************************
+ * Backend XenBus Nodes
+ *****************************************************************************
+ *
+ *---------------------------- Features supported ----------------------------
+ *
+ * Capable backend advertises supported features by publishing
+ * corresponding entries in XenStore and puts 1 as the value of the entry.
+ * If a feature is not supported then 0 must be set or feature entry omitted.
+ *
+ * feature-abs-pointer
+ * Values: <uint>
+ *
+ * Backends, which support reporting of absolute coordinates for pointer
+ * device should set this to 1.
+ *
+ *------------------------- Pointer Device Parameters ------------------------
+ *
+ * width
+ * Values: <uint>
+ *
+ * Maximum X coordinate (width) to be used by the frontend
+ * while reporting input events, pixels, [0; UINT32_MAX].
+ *
+ * height
+ * Values: <uint>
+ *
+ * Maximum Y coordinate (height) to be used by the frontend
+ * while reporting input events, pixels, [0; UINT32_MAX].
+ *
+ *****************************************************************************
+ * Frontend XenBus Nodes
+ *****************************************************************************
+ *
+ *------------------------------ Feature request -----------------------------
+ *
+ * Capable frontend requests features from backend via setting corresponding
+ * entries to 1 in XenStore. Requests for features not advertised as supported
+ * by the backend have no effect.
+ *
+ * request-abs-pointer
+ * Values: <uint>
+ *
+ * Request backend to report absolute pointer coordinates
+ * (XENKBD_TYPE_POS) instead of relative ones (XENKBD_TYPE_MOTION).
+ *
+ *----------------------- Request Transport Parameters -----------------------
+ *
+ * event-channel
+ * Values: <uint>
+ *
+ * The identifier of the Xen event channel used to signal activity
+ * in the ring buffer.
+ *
+ * page-gref
+ * Values: <uint>
+ *
+ * The Xen grant reference granting permission for the backend to map
+ * a sole page in a single page sized event ring buffer.
+ *
+ * page-ref
+ * Values: <uint>
+ *
+ * OBSOLETE, not recommended for use.
+ * PFN of the shared page.
+ */
/*
- * Frontends should ignore unknown in events.
+ * EVENT CODES.
+ */
+
+#define XENKBD_TYPE_MOTION 1
+#define XENKBD_TYPE_RESERVED 2
+#define XENKBD_TYPE_KEY 3
+#define XENKBD_TYPE_POS 4
+
+/*
+ * CONSTANTS, XENSTORE FIELD AND PATH NAME STRINGS, HELPERS.
*/
-/* Pointer movement event */
-#define XENKBD_TYPE_MOTION 1
-/* Event type 2 currently not used */
-/* Key event (includes pointer buttons) */
-#define XENKBD_TYPE_KEY 3
+#define XENKBD_DRIVER_NAME "vkbd"
+
+#define XENKBD_FIELD_FEAT_ABS_POINTER "feature-abs-pointer"
+#define XENKBD_FIELD_REQ_ABS_POINTER "request-abs-pointer"
+#define XENKBD_FIELD_RING_GREF "page-gref"
+#define XENKBD_FIELD_EVT_CHANNEL "event-channel"
+#define XENKBD_FIELD_WIDTH "width"
+#define XENKBD_FIELD_HEIGHT "height"
+
+/* OBSOLETE, not recommended for use */
+#define XENKBD_FIELD_RING_REF "page-ref"
+
/*
- * Pointer position event
- * Capable backend sets feature-abs-pointer in xenstore.
- * Frontend requests ot instead of XENKBD_TYPE_MOTION by setting
- * request-abs-update in xenstore.
+ *****************************************************************************
+ * Description of the protocol between frontend and backend driver.
+ *****************************************************************************
+ *
+ * The two halves of a Para-virtual driver communicate with
+ * each other using a shared page and an event channel.
+ * Shared page contains a ring with event structures.
+ *
+ * All reserved fields in the structures below must be 0.
+ *
+ *****************************************************************************
+ * Backend to frontend events
+ *****************************************************************************
+ *
+ * Frontends should ignore unknown in events.
+ * All event packets have the same length (40 octets)
+ * All event packets have common header:
+ *
+ * 0 octet
+ * +-----------------+
+ * | type |
+ * +-----------------+
+ * type - uint8_t, event code, XENKBD_TYPE_???
+ *
+ *
+ * Pointer relative movement event
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | _TYPE_MOTION | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | rel_x | 8
+ * +----------------+----------------+----------------+----------------+
+ * | rel_y | 12
+ * +----------------+----------------+----------------+----------------+
+ * | rel_z | 16
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 20
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 40
+ * +----------------+----------------+----------------+----------------+
+ *
+ * rel_x - int32_t, relative X motion
+ * rel_y - int32_t, relative Y motion
+ * rel_z - int32_t, relative Z motion (wheel)
*/
-#define XENKBD_TYPE_POS 4
struct xenkbd_motion {
- uint8_t type; /* XENKBD_TYPE_MOTION */
- int32_t rel_x; /* relative X motion */
- int32_t rel_y; /* relative Y motion */
- int32_t rel_z; /* relative Z motion (wheel) */
+ uint8_t type;
+ int32_t rel_x;
+ int32_t rel_y;
+ int32_t rel_z;
};
+/*
+ * Key event (includes pointer buttons)
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | _TYPE_KEY | pressed | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | keycode | 8
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 12
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 40
+ * +----------------+----------------+----------------+----------------+
+ *
+ * pressed - uint8_t, 1 if pressed; 0 otherwise
+ * keycode - uint32_t, KEY_* from linux/input.h
+ */
+
struct xenkbd_key {
- uint8_t type; /* XENKBD_TYPE_KEY */
- uint8_t pressed; /* 1 if pressed; 0 otherwise */
- uint32_t keycode; /* KEY_* from linux/input.h */
+ uint8_t type;
+ uint8_t pressed;
+ uint32_t keycode;
};
+/*
+ * Pointer absolute position event
+ * 0 1 2 3 octet
+ * +----------------+----------------+----------------+----------------+
+ * | _TYPE_POS | reserved | 4
+ * +----------------+----------------+----------------+----------------+
+ * | abs_x | 8
+ * +----------------+----------------+----------------+----------------+
+ * | abs_y | 12
+ * +----------------+----------------+----------------+----------------+
+ * | rel_z | 16
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 20
+ * +----------------+----------------+----------------+----------------+
+ * |/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/|
+ * +----------------+----------------+----------------+----------------+
+ * | reserved | 40
+ * +----------------+----------------+----------------+----------------+
+ *
+ * abs_x - int32_t, absolute X position (in FB pixels)
+ * abs_y - int32_t, absolute Y position (in FB pixels)
+ * rel_z - int32_t, relative Z motion (wheel)
+ */
+
struct xenkbd_position {
- uint8_t type; /* XENKBD_TYPE_POS */
- int32_t abs_x; /* absolute X position (in FB pixels) */
- int32_t abs_y; /* absolute Y position (in FB pixels) */
- int32_t rel_z; /* relative Z motion (wheel) */
+ uint8_t type;
+ int32_t abs_x;
+ int32_t abs_y;
+ int32_t rel_z;
};
#define XENKBD_IN_EVENT_SIZE 40
@@ -75,12 +255,22 @@ union xenkbd_in_event {
char pad[XENKBD_IN_EVENT_SIZE];
};
-/* Out events (frontend -> backend) */
-
/*
+ *****************************************************************************
+ * Frontend to backend events
+ *****************************************************************************
+ *
* Out events may be sent only when requested by backend, and receipt
* of an unknown out event is an error.
* No out events currently defined.
+
+ * All event packets have the same length (40 octets)
+ * All event packets have common header:
+ * 0 octet
+ * +-----------------+
+ * | type |
+ * +-----------------+
+ * type - uint8_t, event code
*/
#define XENKBD_OUT_EVENT_SIZE 40
@@ -90,7 +280,11 @@ union xenkbd_out_event {
char pad[XENKBD_OUT_EVENT_SIZE];
};
-/* shared page */
+/*
+ *****************************************************************************
+ * Shared page
+ *****************************************************************************
+ */
#define XENKBD_IN_RING_SIZE 2048
#define XENKBD_IN_RING_LEN (XENKBD_IN_RING_SIZE / XENKBD_IN_EVENT_SIZE)
@@ -113,4 +307,14 @@ struct xenkbd_page {
uint32_t out_cons, out_prod;
};
-#endif
+#endif /* __XEN_PUBLIC_IO_KBDIF_H__ */
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
--
2.7.4
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