[PATCH 07/10] test: dm: add SCMI base protocol test

[AKASHI Takahiro]

On Fri, Jul 07, 2023 at 11:35:49AM -0600, Simon Glass wrote:
> Hi,
> 
> On Tue, 4 Jul 2023 at 03:35, AKASHI Takahiro <takahiro.akashi at linaro.org> wrote:
> >
> > Hi Simon,
> >
> > On Mon, Jul 03, 2023 at 02:30:57PM +0100, Simon Glass wrote:
> > > Hi,
> > >
> > > On Mon, 3 Jul 2023 at 01:57, AKASHI Takahiro <takahiro.akashi at linaro.org> wrote:
> > > >
> > > > On Thu, Jun 29, 2023 at 08:09:58PM +0100, Simon Glass wrote:
> > > > > Hi AKASHI,
> > > > >
> > > > > On Wed, 28 Jun 2023 at 01:49, AKASHI Takahiro
> > > > > <takahiro.akashi at linaro.org> wrote:
> > > > > >
> > > > > > Added is a new unit test for SCMI base protocol, which will exercise all
> > > > > > the commands provided by the protocol, except SCMI_BASE_NOTIFY_ERRORS.
> > > > > >   $ ut dm scmi_base
> > > > > > It is assumed that test.dtb is used as sandbox's device tree.
> > > > > >
> > > > > > Signed-off-by: AKASHI Takahiro <takahiro.akashi at linaro.org>
> > > > > > ---
> > > > > >  test/dm/scmi.c | 112 +++++++++++++++++++++++++++++++++++++++++++++++++
> > > > > >  1 file changed, 112 insertions(+)
> > > > > >
> > > > > > diff --git a/test/dm/scmi.c b/test/dm/scmi.c
> > > > > > index 881be3171b7c..563017bb63e0 100644
> > > > > > --- a/test/dm/scmi.c
> > > > > > +++ b/test/dm/scmi.c
> > > > > > @@ -16,6 +16,9 @@
> > > > > >  #include <clk.h>
> > > > > >  #include <dm.h>
> > > > > >  #include <reset.h>
> > > > > > +#include <scmi_agent.h>
> > > > > > +#include <scmi_agent-uclass.h>
> > > > > > +#include <scmi_protocols.h>
> > > > > >  #include <asm/scmi_test.h>
> > > > > >  #include <dm/device-internal.h>
> > > > > >  #include <dm/test.h>
> > > > > > @@ -95,6 +98,115 @@ static int dm_test_scmi_sandbox_agent(struct unit_test_state *uts)
> > > > > >  }
> > > > > >  DM_TEST(dm_test_scmi_sandbox_agent, UT_TESTF_SCAN_FDT);
> > > > > >
> > > > > > +static int dm_test_scmi_base(struct unit_test_state *uts)
> > > > > > +{
> > > > > > +       struct udevice *agent_dev, *base;
> > > > > > +       struct scmi_agent_priv *priv;
> > > > > > +       const struct scmi_base_ops *ops;
> > > > > > +       u32 version, num_agents, num_protocols, impl_version;
> > > > > > +       u32 attributes, agent_id;
> > > > > > +       char vendor[SCMI_BASE_NAME_LENGTH_MAX],
> > > > > > +            agent_name[SCMI_BASE_NAME_LENGTH_MAX];
> > > > > > +       u8 *protocols;
> > > > > > +       int ret;
> > > > > > +
> > > > > > +       /* preparation */
> > > > > > +       ut_assertok(uclass_get_device_by_name(UCLASS_SCMI_AGENT, "scmi",
> > > > > > +                                             &agent_dev));
> > > > > > +       ut_assertnonnull(agent_dev);
> > > > > > +       ut_assertnonnull(priv = dev_get_uclass_plat(agent_dev));
> > > > > > +       ut_assertnonnull(base = scmi_get_protocol(agent_dev,
> > > > > > +                                                 SCMI_PROTOCOL_ID_BASE));
> > > > > > +       ut_assertnonnull(ops = dev_get_driver_ops(base));
> > > > > > +
> > > > > > +       /* version */
> > > > > > +       ret = (*ops->protocol_version)(base, &version);
> > > > >
> > > > > Can you add uclass helpers to call each of the methods? That is how it
> > > > > is commonly done. You should not be calling ops->xxx directly here.
> > > >
> > > > Yes, I will add inline functions instead.
> > >
> > > I don't mean inline...see all the other uclasses which define a
> >
> > Okay, I will *real* functions.
> >
> > > function which is implemented in the uclass. It is confusing when one
> > > uclass does something different. People might copy this style and then
> > > the code base diverges. Did you not notice this when looking around
> > > the source tree?
> >
> > But one concern came up in my mind.
> > Contrary to ordinary "device controllers", there exists only a single
> > implementation of driver for each of "udevice"'s associated with SCMI
> > protocols including the base protocol.
> >
> > So if I follow your suggestion, the code (base.c) might look like:
> > ===
> > static int __scmi_base_discover_vendor(struct udevice *dev, u8 *vendor)
> > {
> >   ...
> > }
> >
> > struct scmi_base_ops scmi_base_ops = {
> >
> >   .base_discover_vendor = __scmi_base_discover_vendor,
> >
> > }
> >
> > int scmi_base_discover_vendor(struct udevice *dev, u8 *vendor)
> > {
> >   struct scmi_base_ops *ops;
> >
> >   ops = scmi_base_dev_ops(dev);
> >
> >   return ops->base_discover_vendor(dev, vendor);
> > }
> > ===
> >
> > We will have to have similar definitions for every operation in ops.
> > It looks quite weird to me as there are always pairs of functions,
> > like __scmi_base_discover_vendor() and scmi_base_discover_vendor().
> 
> Yes I understand that you only have one driver at present. Is there
> not a sandbox driver?

No.
Please remember that SCMI protocol drivers on U-Boot are nothing but
stubs that makes a call to SCMI servers, supporting common communication
channel interfaces for different transports (either OP-TEE, SMCCC or mailbox).

Sandbox driver, if is properly named, is also implemented as a sort of
transport layer, where a invocation is replaced with a function call which
mimicks one of specific commands in SCMI protocol on behalf of a real SCMI server.

In this sense, there will exist only a single driver under the current
form of framework forever.

> 
> >
> > We can avoid this redundant code easily by eliminating "ops" abstraction.
> > But as far as I remember, you insist that every driver that complies
> > to U-Boot driver model should have a "ops".
> >
> > What do you make of this?
> 
> Well there are some exceptions, but yes that is the idea. Operations
> should be in a 'ops' struct and documented and implemented in a
> consistent way.

Is it your choice that I should keep "ops" structure in this specific
implementation?

-Takahiro Akashi

> Regards,
> Simon