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SubjectRE: [PATCH V2 2/2] firmware: arm_scmi: add smc/hvc transports
Date
Hi Sudeep,

> Subject: Re: [PATCH V2 2/2] firmware: arm_scmi: add smc/hvc transports
>
> On Thu, Feb 13, 2020 at 11:58:50AM +0800, peng.fan@nxp.com wrote:
> > From: Peng Fan <peng.fan@nxp.com>
> >
> > Add SCMI smc/hvc transports support.
> >
> > Take smc-id as the 2nd arg, and protocol id as the 2nd arg when
> > invokding SMC/HVC. Since we need protocol id, so add this parrameter
> > to chan_setup, then smc transport driver could directly use it.
> > There is no Rx, only Tx because of smc/hvc not support Rx.
> >
> > Signed-off-by: Peng Fan <peng.fan@nxp.com>
> > ---
> > drivers/firmware/arm_scmi/Makefile | 2 +-
> > drivers/firmware/arm_scmi/common.h | 4 +-
> > drivers/firmware/arm_scmi/driver.c | 11 +-
> > drivers/firmware/arm_scmi/mailbox.c | 2 +-
> > drivers/firmware/arm_scmi/smc.c | 222
> ++++++++++++++++++++++++++++++++++++
> > 5 files changed, 234 insertions(+), 7 deletions(-) create mode
> > 100644 drivers/firmware/arm_scmi/smc.c
>
> [...]
>
> >
> > diff --git a/drivers/firmware/arm_scmi/driver.c
> > b/drivers/firmware/arm_scmi/driver.c
> > index dbec767222e9..65c56328e6d8 100644
> > --- a/drivers/firmware/arm_scmi/driver.c
> > +++ b/drivers/firmware/arm_scmi/driver.c
> > @@ -595,7 +595,7 @@ static int scmi_chan_setup(struct scmi_info *info,
> > struct device *dev,
> >
> > cinfo->dev = dev;
> >
> > - ret = info->desc->ops->chan_setup(cinfo, info->dev, tx);
> > + ret = info->desc->ops->chan_setup(cinfo, info->dev, prot_id, tx);
>
> Why do you need this ?

For smc tranports, all protocols share same smd-id, but if protocols
not share the same shmem, we need let firmare know which protocol
issues the smc call. So I take prot_id as an arguments of smc call.

>
> > if (ret)
> > return ret;
> >
> > @@ -826,7 +829,7 @@ ATTRIBUTE_GROUPS(versions);
> >
> > /* Each compatible listed below must have descriptor associated with
> > it */ static const struct of_device_id scmi_of_match[] = {
> > - { .compatible = "arm,scmi", .data = &scmi_mailbox_desc },
> > + { .compatible = "arm,scmi", },
>
> Don't do this, get "arm,scmi-smc"

You mean code as below?
/* Each compatible listed below must have descriptor associated with it */
static const struct of_device_id scmi_of_match[] = {
{ .compatible = "arm,scmi", .data = &scmi_mailbox_desc },
{ .compatible = "arm,scmi-smc", .data = &scmi_smc_desc },
{ /* Sentinel */ },
};

But since we could use mboxes and smc-id to know the tranports type,
do we really need arm,scmi-smc?

>
> > { /* Sentinel */ },
> > };
> >
> [...]
>
>
> > +static unsigned long
> > +__invoke_scmi_fn_hvc(unsigned long function_id, unsigned long arg0,
> > + unsigned long arg1, unsigned long arg2,
> > + unsigned long arg3, unsigned long arg4,
> > + unsigned long arg5, unsigned long arg6) {
> > + struct arm_smccc_res res;
> > +
> > + arm_smccc_hvc(function_id, arg0, arg1, arg2, arg3, arg4, arg5,
> > + arg6, &res);
> > +
> > + return res.a0;
> > +}
> > +
> > +static unsigned long
> > +__invoke_scmi_fn_smc(unsigned long function_id, unsigned long arg0,
> > + unsigned long arg1, unsigned long arg2,
> > + unsigned long arg3, unsigned long arg4,
> > + unsigned long arg5, unsigned long arg6) {
> > + struct arm_smccc_res res;
> > +
> > + arm_smccc_smc(function_id, arg0, arg1, arg2, arg3, arg4, arg5,
> > + arg6, &res);
> > +
> > + return res.a0;
> > +}
> > +
> > +static int scmi_smc_conduit_method(struct device_node *np) {
> > + const char *method;
> > +
> > + if (invoke_scmi_smc_fn)
> > + return 0;
> > +
> > + if (of_property_read_string(np, "method", &method))
> > + return -ENXIO;
> > +
> > + if (!strcmp("hvc", method)) {
> > + invoke_scmi_smc_fn = __invoke_scmi_fn_hvc;
> > + } else if (!strcmp("smc", method)) {
> > + invoke_scmi_smc_fn = __invoke_scmi_fn_smc;
> > + } else {
> > + pr_warn("invalid \"method\" property: %s\n", method);
> > + return -EINVAL;
> > + }
> > +
> > + return 0;
> > +}
> > +
>
> You don't the above functions

ok

>
> [...]
>
> > +
> > + np = of_find_node_by_path("/psci");
> > + if (!np) {
> > + dev_err(dev, "Not able to find /psci node\n");
> > + return -ENODEV;
> > + }
>
> No need for this as mentioned below.

ok

>
> > +
> > + ret = scmi_smc_conduit_method(np);
>
> Just use arm_smccc_1_1_get_conduit if you want to get the conduit which I
> don't think you need. You can just use arm_smccc_1_1_invoke() directly.

Fix in v3.

I'll post v3 after we have an agreement on whether we need a new compatible
string arm,scmi-smc and the prot_id introduced in chan_setup.

Thanks,
Peng.

>
> --
> Regards,
> Sudeep

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