On Tue, Nov 6, 2018 at 6:33 PM Alex Elder [off-list ref] wrote:

Bindings are for h/w not drivers.

+
+This binding describes the Qualcomm IPA.  The IPA is capable of offloading
+certain network processing tasks (e.g. filtering, routing, and NAT) from
+the main processor.  The IPA currently serves only as a network interface,
+providing access to an LTE network available via a modem.
+
+The IPA sits between multiple independent "execution environments,"
+including the AP subsystem (APSS) and the modem.  The IPA presents
+a Generic Software Interface (GSI) to each execution environment.
+The GSI is an integral part of the IPA, but it is logically isolated
+and has a distinct interrupt and a separately-defined address space.
+
+    ----------   -------------   ---------
+    |        |   |G|       |G|   |       |
+    |  APSS  |===|S|  IPA  |S|===| Modem |
+    |        |   |I|       |I|   |       |
+    ----------   -------------   ---------
+
+See also:
+  bindings/interrupt-controller/interrupts.txt
+  bindings/interconnect/interconnect.txt
+  bindings/soc/qcom/qcom,smp2p.txt
+  bindings/reserved-memory/reserved-memory.txt
+  bindings/clock/clock-bindings.txt
+
+All properties defined below are required.
+
+- compatible:
+       Must be one of the following compatible strings:
+               "qcom,ipa-sdm845-modem_init"
+               "qcom,ipa-sdm845-tz_init"

Normal order is <vendor>,<soc>-<ipblock>.

Don't use '_'.

What's the difference between these 2? It can't be detected somehow?
This might be better expressed as a property. Then if Trustzone
initializes things, it can just add a property.

+
+-reg:
+       Resources specyfing the physical address spaces of the IPA and GSI.

typo

+
+-reg-names:
+       The names of the address space ranges defined by the "reg" property.
+       Must be "ipa" and "gsi".
+
+- interrupts-extended:

Use 'interrupts' here and describe what they are and the order. What
they are connected to (and the need for interrupts-extended) is
outside the scope of this binding.

+       Specifies the IRQs used by the IPA.  Four cells are required,
+       specifying: the IPA IRQ; the GSI IRQ; the clock query interrupt
+       from the modem; and the "ready for stage 2 initialization"
+       interrupt from the modem.  The first two are hardware IRQs; the
+       third and fourth are SMP2P input interrupts.
+
+- interrupt-names:
+       The names of the interrupts defined by the "interrupts-extended"
+       property.  Must be "ipa", "gsi", "ipa-clock-query", and
+       "ipa-post-init".

Format as one per line.

+
+- clocks:
+       Resource that defines the IPA core clock.
+
+- clock-names:
+       The name used for the IPA core clock.  Must be "core".
+
+- interconnects:
+       Specifies the interconnects used by the IPA.  Three cells are
+       required, specifying:  the path from the IPA to memory; from
+       IPA to internal (SoC resident) memory; and between the AP
+       subsystem and IPA for register access.
+
+- interconnect-names:
+       The names of the interconnects defined by the "interconnects"
+       property.  Must be "memory", "imem", and "config".
+
+- qcom,smem-states
+       The state bits used for SMP2P output.  Two cells must be specified.
+       The first indicates whether the value in the second bit is valid
+       (1 means valid).  The second, if valid, defines whether the IPA
+       clock is enabled (1 means enabled).
+
+- qcom,smem-state-names
+       The names of the state bits used for SMP2P output.  These must be
+       "ipa-clock-enabled-valid" and "ipa-clock-enabled".
+
+- memory-region
+       A phandle for a reserved memory area that holds the firmware passed
+       to Trust Zone for authentication.  (Note, this is required
+       only for "qcom,ipa-sdm845-tz_init".)
+
+= EXAMPLE
+
+The following example represents the IPA present in the SDM845 SoC.  It
+shows portions of the "modem-smp2p" node to indicate its relationship
+with the interrupts and SMEM states used by the IPA.
+
+       modem-smp2p {
+               compatible = "qcom,smp2p";
+               . . .
+               ipa_smp2p_out: ipa-ap-to-modem {
+                       qcom,entry-name = "ipa";
+                       #qcom,smem-state-cells = <1>;
+               };
+
+               ipa_smp2p_in: ipa-modem-to-ap {
+                       qcom,entry-name = "ipa";
+                       interrupt-controller;
+                       #interrupt-cells = <2>;
+               };
+       };
+
+       ipa@1e00000 {

ipa@1e40000

Only a compatible string is a sure sign this is not a h/w device and
you are just abusing DT to instantiate drivers. Make the IPA driver
instantiate any sub drivers it needs.

Rob