MLK-25346: net: add imx-shmem-net driver

This driver uses the shared memory and the mailbox units to
provide a virtual network interface toward a peer device on
the same SoC. This new driver is based on ivshmem-net driver,
where we replace ivshmem's registers by struct 'regs' in the
context, and push in MU all modifications to 'regs' value lstate.

FEATURES:
Only 2 identical devices in different HW partitions and connected
by an MU can talk to each other.
All MU transaction may timeout: if first message sent through MU,
then the driver will be probed again.
The driver supports peer's partition reset:
driver registers to SCFW service to receive a notification when
peer's partition resets.
The driver supports multiple devices
(i.e. multiple connections to different partitions).

Signed-off-by: Seb Fagard <sebastien.fagard@nxp.com>
Signed-off-by: Nitin Garg <nitin.garg@nxp.com>
Signed-off-by: Abel Vesa <abel.vesa@nxp.com>
(cherry picked from commit 1730a5e196055cef89fe50dd63852ebc32cce135)

1 files changed, 37 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/net/imx-shmem-net.txt b/Documentation/devicetree/bindings/net/imx-shmem-net.txt
new file mode 100644
index 000000000000..e1fe220c5a41
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/imx-shmem-net.txt
@@ -0,0 +1,37 @@
+i.MX SHMEM-NET implementations
+
+A network device to communicate with another domain.
+Communication is done through shared memory
+ and synchronized by Mailbox Units of imx.
+Use Mailbox Units side A to communicate with side B.
+
+Required properties:
+- compatible : "fsl,imx-shmem-net".
+- rxfirst: The flag that indicates the position of the RX buffer,
+  one of the two partitions must set it.
+- mub-partition: The id number of the remote processors,
+  used on i.mx8qm for partition reset. The default
+  value is 3 in driver without this property.
+- mbox-names: the mailbox channel names.
+- mboxes: the mailboxes list containing:
+  MU name, channel type (0 for TX, 1 for RX) and channel id.
+- memory-region: the coherent memory shared across domains.
+
+=====================================================================
+
+Example:
+
+imx_shmem_net: imx_shmem_net {
+	compatible = "fsl,imx-shmem-net";
+	mub-partition = <1>;
+	mbox-names = "tx", "rx";
+	mboxes = <&lsio_mu8b 0 1
+			  &lsio_mu8b 1 1>;
+	status = "disabled";
+};
+
+&imx_shmem_net{
+	memory-region = <&shmem_dma_reserved>;
+	status = "okay";
+};
+