Re: [RFC V3 2/4] firmware: arm_scmi: vendors: Add ARM SCMI QCOM vendor protocol v1.0

[Sibi Sankar]

On 7/9/24 23:22, Cristian Marussi wrote:
> On Wed, Jul 03, 2024 at 12:44:38AM +0530, Sibi Sankar wrote:
> > The ARM SCMI QCOM vendor protocol provides a generic way of exposing a
> > number of Qualcomm SoC specific features (like memory bus scaling) through
> > a mixture of pre-determined algorithm strings and param_id pairs hosted on
> > the SCMI controller.
>
> Hi Sibi,
>
> > Co-developed-by: Shivnandan Kumar <quic_kshivnan@xxxxxxxxxxx>
> > Signed-off-by: Shivnandan Kumar <quic_kshivnan@xxxxxxxxxxx>
> > Co-developed-by: Ramakrishna Gottimukkula <quic_rgottimu@xxxxxxxxxxx>
> > Signed-off-by: Ramakrishna Gottimukkula <quic_rgottimu@xxxxxxxxxxx>
> > Co-developed-by: Amir Vajid <avajid@xxxxxxxxxxx>
> > Signed-off-by: Amir Vajid <avajid@xxxxxxxxxxx>
> > Signed-off-by: Sibi Sankar <quic_sibis@xxxxxxxxxxx>
> > ---
> >   drivers/firmware/arm_scmi/vendors/Kconfig     |  12 ++
> >   drivers/firmware/arm_scmi/vendors/Makefile    |   2 +-
> >   .../arm_scmi/vendors/qcom_scmi_vendor.c       | 184 ++++++++++++++++++
> >   include/linux/qcom_scmi_vendor.h              |  39 ++++
> >   4 files changed, 236 insertions(+), 1 deletion(-)
> >   create mode 100644 drivers/firmware/arm_scmi/vendors/qcom_scmi_vendor.c
> >   create mode 100644 include/linux/qcom_scmi_vendor.h
> >
> > diff --git a/drivers/firmware/arm_scmi/vendors/Kconfig b/drivers/firmware/arm_scmi/vendors/Kconfig
> > index 7c1ca7a12603..6bff4550fa25 100644
> > --- a/drivers/firmware/arm_scmi/vendors/Kconfig
> > +++ b/drivers/firmware/arm_scmi/vendors/Kconfig
> > @@ -1,4 +1,16 @@
> >   # SPDX-License-Identifier: GPL-2.0-only
> >   menu "ARM SCMI Vendor Protocols"
> >   
> > +config ARM_SCMI_PROTOCOL_VENDOR_QCOM
> > +	tristate "Qualcomm Technologies, Inc. Qcom SCMI vendor Protocol"
> > +	depends on ARM_SCMI_PROTOCOL || COMPILE_TEST
> > +	help
> > +	  The SCMI QCOM vendor protocol provides a generic way of exposing a
> > +	  number of Qualcomm SoC specific features (like memory bus scaling)
> > +	  through a mixture of pre-determined algorithm strings and param_id
> > +	  pairs hosted on the SCMI controller.
> > +
> > +	  This driver defines/documents the message ID's used for this
> > +	  communication and also exposes the ops used by the clients.
>
> operations
>
> > +
> >   endmenu
> > diff --git a/drivers/firmware/arm_scmi/vendors/Makefile b/drivers/firmware/arm_scmi/vendors/Makefile
> > index c6c214158dd8..c1d6a355f579 100644
> > --- a/drivers/firmware/arm_scmi/vendors/Makefile
[...]
> > +++ b/drivers/firmware/arm_scmi/vendors/Makefile
> > +	if (ret)
> > +		return ret;
> > +
> > +	msg = t->tx.buf;
> > +	msg->algo_low = cpu_to_le32(lower_32_bits(algo_str));
> > +	msg->algo_high = cpu_to_le32(upper_32_bits(algo_str));
> > +	msg->param_id = cpu_to_le32(param_id);
> > +
> > +	memcpy(msg->buf, buf, t->tx.len - sizeof(*msg));
> > +
> > +	ret = ph->xops->do_xfer(ph, t);
> > +	ph->xops->xfer_put(ph, t);
> > +
> > +	return ret;
> > +}
> > +
> > +static int qcom_scmi_get_param(const struct scmi_protocol_handle *ph, void *buf, u64 algo_str,
> > +			       u32 param_id, size_t tx_size, size_t rx_size)
> > +{
>
> Similarly...and looking at my past ramblings...this rx_size is the expected RX
> size AND also the size of the provided *buf too, right ?
>
> > +	struct scmi_xfer *t;
> > +	struct qcom_scmi_msg *msg;
> > +	int ret;
> > +
> > +	ret = ph->xops->xfer_get_init(ph, QCOM_SCMI_GET_PARAM, tx_size + sizeof(*msg), rx_size, &t);
> > +	if (ret)
> > +		return ret;
> > +
> > +	msg = t->tx.buf;
> > +	msg->algo_low = cpu_to_le32(lower_32_bits(algo_str));
> > +	msg->algo_high = cpu_to_le32(upper_32_bits(algo_str));
> > +	msg->param_id = cpu_to_le32(param_id);
> > +	memcpy(msg->buf, buf, t->tx.len - sizeof(*msg));
> > +
> > +	ret = ph->xops->do_xfer(ph, t);
> > +	memcpy(buf, t->rx.buf, t->rx.len);
>
> ...so that this memcpy is safe since rx.len is equal to rx_size by construction
> (if I read correctly my past review/mublings...)
>
> ...in that case maybe, for better clarity you could re-name the rx_size
> param as buf_len and have it following *buf in the param list...
>
>
> ...sorry for not having spotted this naming/order niptick earlier ...

the only caveat being rx_size can be lower than the tx_size
and we dont't want to copy more that what we expect. Addressed
all your other comments from the series in V4. Sry it took a
while due to its dependency with scmi perf changes. Thanks
again.

-Sibi

[...]
> Thanks,
> Cristian