[PATCH 25/27 v11] xen/arm: vpl011: Update documentation for vuart console support

[Bhupinder Thakur <bhupinder.thakur@linaro.org>]

1. Update documentation for a new vuart option added.
2. Update documentation about SPI irq reserved for vuart.

Signed-off-by: Bhupinder Thakur <bhupinder.thakur@linaro.org>
Reviewed-by: Stefano Stabellini <sstabellini@kernel.org>
Acked-by: Wei Liu <wei.liu2@citrix.com>
---
CC: Ian Jackson <ian.jackson@eu.citrix.com>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Andrew Cooper <andrew.cooper3@citrix.com>
CC: George Dunlap <George.Dunlap@eu.citrix.com>
CC: Jan Beulich <jbeulich@suse.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Tim Deegan <tim@xen.org>
CC: Julien Grall <julien.grall@arm.com>

Changes since v6:
- Added a new section for vuart usage.
- I have retained the reviewed-by/acked-by tags as this is a limited change. Kindly
  review.

Changes since v4:
- Minor change to rename "pl011" to "sbsa_uart". Since it is a minor change I have
  retained the reviewed-by and acked-by tags.

 docs/man/xl.cfg.pod.5.in | 12 ++++++++++++
 docs/misc/console.txt    | 44 +++++++++++++++++++++++++++++++++-----------
 2 files changed, 45 insertions(+), 11 deletions(-)

diff --git a/docs/man/xl.cfg.pod.5.in b/docs/man/xl.cfg.pod.5.in
index 247ae99..f1d2a7a 100644
--- a/docs/man/xl.cfg.pod.5.in
+++ b/docs/man/xl.cfg.pod.5.in
@@ -1105,6 +1105,9 @@ Allow a guest to access specific physical IRQs.
 It is recommended to only use this option for trusted VMs under
 administrator's control.
 
+If vuart console is enabled then irq 32 is reserved for it. See
+L</vuart="uart"> to know how to enable vuart console.
+
 =item B<max_event_channels=N>
 
 Limit the guest to using at most N event channels (PV interrupts).
@@ -2220,6 +2223,15 @@ the domain was created.
 This requires hardware compatibility with the requested version, either
 natively or via hardware backwards compatibility support.
 
+=item B<vuart="uart">
+
+To enable vuart console, user must specify the following option in the
+VM config file:
+
+vuart = "sbsa_uart"
+
+Currently, only the "sbsa_uart" model is supported for ARM.
+
 =back
 
 =head3 x86
diff --git a/docs/misc/console.txt b/docs/misc/console.txt
index 16da805..4e180f8 100644
--- a/docs/misc/console.txt
+++ b/docs/misc/console.txt
@@ -19,7 +19,20 @@ The first PV console path in xenstore remains:
 
 /local/domain/$DOMID/console
 
-the other PV consoles follow the conventional xenstore device path and
+The virtual UART console path in xenstore is defined as:
+
+/local/domain/$DOMID/vuart/0
+
+The vuart console provides access to a virtual SBSA UART on ARM systems.
+To enable vuart the following line has to be added to the guest configuration
+file:
+
+vuart = "sbsa_uart"
+
+In Linux you can select the virtual SBSA UART by using the "ttyAMA0"
+console instead of "hvc0".
+
+The other PV consoles follow the conventional xenstore device path and
 live in:
 
 /local/domain/$DOMID/device/console/$DEVID.
@@ -61,6 +74,14 @@ output = pty
 The backend will write the pty device name to the "tty" node in the
 console frontend.
 
+For the PV console the tty node is added at
+
+/local/domain/$DOMID/console/tty
+
+For the virtual UART console the tty node is added at
+
+/local/domain/$DOMID/vuart/0/tty
+
 If the toolstack wants a listening Unix domain socket to be created at path
 <path>, a connection accepted and data proxied to the console, it will write:
 
@@ -79,8 +100,8 @@ For example:
 ioemu
 
 The supported values are only xenconsoled or ioemu; xenconsoled has
-several limitations: it can only be used for the first PV console and it
-can only connect to a pty.
+several limitations: it can only be used for the first PV or virtual UART
+console and it can only connect to a pty.
 
 Emulated serials are provided by qemu-dm only to hvm guests; the number
 of emulated serials depends on how many "-serial" command line options
@@ -90,14 +111,15 @@ xenstore in the following path:
 
 /local/domain/$DOMID/serial/$SERIAL_NUM/tty
 
-xenconsole is the tool to connect to a PV console or an emulated serial
-that has a pty as output. Xenconsole takes a domid as parameter plus an
-optional console type (pv for PV consoles or serial for emulated
-serials) and console number. Depending on the type and console
-number, xenconsole will look for the tty node in different xenstore
-paths, as described above.  If the user doesn't specify the console type
-xenconsole will try to guess: if the guest is a pv guest it defaults to
-PV console, if the guest is an hvm guest it defaults to emulated serial.
+xenconsole is the tool to connect to a PV or virtual UART console or an
+emulated serial that has a pty as output. Xenconsole takes a domid as
+parameter plus an optional console type (pv for PV consoles, vuart for
+virtual UART or serial for emulated serials) and console number.
+Depending on the type and console number, xenconsole will look for the tty
+node in different xenstore paths, as described above.  If the user doesn't
+specify the console type xenconsole will try to guess: if the guest is a pv
+guest it defaults to PV console, if the guest is an hvm guest it defaults to
+emulated serial.
 
 By default xl creates a pv console for hvm guests, plus an emulated
 serial if the user specified 'serial = "pty"' in the VM config file.
-- 
2.7.4


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