Re: [PATCH v5 1/5] firmware: arm_scmi: Add Voltage Domain Support

[Sudeep Holla]

On Tue, Nov 17, 2020 at 12:34:11PM +0000, Cristian Marussi wrote:
> Add SCMI Voltage Domain protocol support.
> 
> Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> ---
> v4 --> v5
> - removed inline
> - moved segmented intervals defines
> - fixed some macros complaints by checkpatch
> 
> v3 --> v4
> - avoid fixed sized typing in voltage_info
> - avoid coccinelle falde complaints about pointer-sized allocations
> 
> v2 --> v3
> - restrict segmented voltage domain descriptors to one triplet
> - removed unneeded inline
> - free allocated resources for invalid voltage domain
> - added __must_check to info_get voltage operations
> - added a few comments
> - removed fixed size typing from struct voltage_info
> 
> v1 --> v2
> - fix voltage levels query loop to reload full cmd description
>   between iterations as reported by Etienne Carriere
> - ensure rx buffer is properly sized calli scmi_reset_rx_to_maxsz
>   between transfers
> ---
>  drivers/firmware/arm_scmi/Makefile  |   2 +-
>  drivers/firmware/arm_scmi/common.h  |   1 +
>  drivers/firmware/arm_scmi/driver.c  |   2 +
>  drivers/firmware/arm_scmi/voltage.c | 397 ++++++++++++++++++++++++++++
>  include/linux/scmi_protocol.h       |  64 +++++
>  5 files changed, 465 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/firmware/arm_scmi/voltage.c
> 
> diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
> index bc0d54f8e861..6a2ef63306d6 100644
> --- a/drivers/firmware/arm_scmi/Makefile
> +++ b/drivers/firmware/arm_scmi/Makefile
> @@ -4,7 +4,7 @@ scmi-driver-y = driver.o notify.o
>  scmi-transport-y = shmem.o
>  scmi-transport-$(CONFIG_MAILBOX) += mailbox.o
>  scmi-transport-$(CONFIG_HAVE_ARM_SMCCC_DISCOVERY) += smc.o
> -scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o
> +scmi-protocols-y = base.o clock.o perf.o power.o reset.o sensors.o system.o voltage.o
>  scmi-module-objs := $(scmi-bus-y) $(scmi-driver-y) $(scmi-protocols-y) \
>  		    $(scmi-transport-y)
>  obj-$(CONFIG_ARM_SCMI_PROTOCOL) += scmi-module.o
> diff --git a/drivers/firmware/arm_scmi/common.h b/drivers/firmware/arm_scmi/common.h
> index 65063fa948d4..c0fb45e7c3e8 100644
> --- a/drivers/firmware/arm_scmi/common.h
> +++ b/drivers/firmware/arm_scmi/common.h
> @@ -169,6 +169,7 @@ DECLARE_SCMI_REGISTER_UNREGISTER(perf);
>  DECLARE_SCMI_REGISTER_UNREGISTER(power);
>  DECLARE_SCMI_REGISTER_UNREGISTER(reset);
>  DECLARE_SCMI_REGISTER_UNREGISTER(sensors);
> +DECLARE_SCMI_REGISTER_UNREGISTER(voltage);
>  DECLARE_SCMI_REGISTER_UNREGISTER(system);
>  
>  #define DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(id, name) \
> diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
> index 3dfd8b6a0ebf..ada35e63feae 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -946,6 +946,7 @@ static int __init scmi_driver_init(void)
>  	scmi_power_register();
>  	scmi_reset_register();
>  	scmi_sensors_register();
> +	scmi_voltage_register();
>  	scmi_system_register();
>  
>  	return platform_driver_register(&scmi_driver);
> @@ -961,6 +962,7 @@ static void __exit scmi_driver_exit(void)
>  	scmi_power_unregister();
>  	scmi_reset_unregister();
>  	scmi_sensors_unregister();
> +	scmi_voltage_unregister();
>  	scmi_system_unregister();
>  
>  	platform_driver_unregister(&scmi_driver);
> diff --git a/drivers/firmware/arm_scmi/voltage.c b/drivers/firmware/arm_scmi/voltage.c
> new file mode 100644
> index 000000000000..6b71589e0846
> --- /dev/null
> +++ b/drivers/firmware/arm_scmi/voltage.c
> @@ -0,0 +1,397 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * System Control and Management Interface (SCMI) Voltage Protocol
> + *
> + * Copyright (C) 2020 ARM Ltd.
> + */
> +
> +#include <linux/scmi_protocol.h>
> +
> +#include "common.h"
> +
> +#define VOLTAGE_DOMS_NUM_MASK		GENMASK(15, 0)
> +#define REMAINING_LEVELS_MASK		GENMASK(31, 16)
> +#define RETURNED_LEVELS_MASK		GENMASK(11, 0)
> +
> +enum scmi_voltage_protocol_cmd {
> +	VOLTAGE_DOMAIN_ATTRIBUTES = 0x3,
> +	VOLTAGE_DESCRIBE_LEVELS = 0x4,
> +	VOLTAGE_CONFIG_SET = 0x5,
> +	VOLTAGE_CONFIG_GET = 0x6,
> +	VOLTAGE_LEVEL_SET = 0x7,
> +	VOLTAGE_LEVEL_GET = 0x8,
> +};
> +
> +struct scmi_msg_resp_protocol_attributes {
> +	__le32 attr;
> +#define NUM_VOLTAGE_DOMAINS(x)	((u16)(FIELD_GET(VOLTAGE_DOMS_NUM_MASK, (x))))
> +};
> +

Sorry but same annoying comment again, drop one element structures.

> +struct scmi_msg_resp_domain_attributes {
> +	__le32 attr;
> +	u8 name[SCMI_MAX_STR_SIZE];
> +};
> +
> +struct scmi_msg_cmd_describe_levels {
> +	__le32 domain_id;
> +	__le32 level_index;
> +};
> +
> +struct scmi_msg_resp_describe_levels {
> +	__le32 flags;
> +#define NUM_REMAINING_LEVELS(f)	((u16)(FIELD_GET(REMAINING_LEVELS_MASK, (f))))
> +#define NUM_RETURNED_LEVELS(f)	((u16)(FIELD_GET(RETURNED_LEVELS_MASK, (f))))
> +#define SUPPORTS_SEGMENTED_LEVELS(f)	((f) & BIT(12))
> +	__le32 voltage[];
> +};
> +
> +struct scmi_msg_cmd_config_set {
> +	__le32 domain_id;
> +	__le32 config;
> +};
> +
> +struct scmi_msg_cmd_level_set {
> +	__le32 domain_id;
> +	__le32 flags;
> +	__le32 voltage_level;
> +};
> +
> +struct voltage_info {
> +	unsigned int version;
> +	unsigned int num_domains;
> +	struct scmi_voltage_info **domains;
> +};
> +
> +static int scmi_protocol_attributes_get(const struct scmi_handle *handle,
> +					struct voltage_info *vinfo)
> +{
> +	int ret;
> +	struct scmi_xfer *t;
> +	struct scmi_msg_resp_protocol_attributes *resp;
> +
> +	ret = scmi_xfer_get_init(handle, PROTOCOL_ATTRIBUTES,
> +				 SCMI_PROTOCOL_VOLTAGE, 0, sizeof(*resp), &t);
> +	if (ret)
> +		return ret;
> +
> +	resp = t->rx.buf;
> +	ret = scmi_do_xfer(handle, t);
> +	if (!ret)
> +		vinfo->num_domains =
> +			NUM_VOLTAGE_DOMAINS(le32_to_cpu(resp->attr));
> +
> +	scmi_xfer_put(handle, t);
> +	return ret;
> +}
> +
> +static int scmi_init_voltage_levels(struct device *dev,
> +				    struct scmi_voltage_info *v,
> +				    u32 flags, u32 num_returned,
> +				    u32 num_remaining)
> +{
> +	bool segmented;
> +	u32 num_levels;
> +

Why can't you pass the above 2 directly from the caller to this function
since they are just used to obtain them here.


[...]

> +static int scmi_voltage_descriptors_get(const struct scmi_handle *handle,
> +					struct voltage_info *vinfo)
> +{
> +	int ret, dom;
> +	struct scmi_xfer *td, *tl;
> +	struct device *dev = handle->dev;
> +	struct scmi_msg_resp_domain_attributes *resp_dom;
> +	struct scmi_msg_resp_describe_levels *resp_levels;
> +
> +	ret = scmi_xfer_get_init(handle, VOLTAGE_DOMAIN_ATTRIBUTES,
> +				 SCMI_PROTOCOL_VOLTAGE, sizeof(__le32),
> +				 sizeof(*resp_dom), &td);
> +	if (ret)
> +		return ret;
> +	resp_dom = td->rx.buf;
> +
> +	ret = scmi_xfer_get_init(handle, VOLTAGE_DESCRIBE_LEVELS,
> +				 SCMI_PROTOCOL_VOLTAGE, sizeof(__le64), 0, &tl);
> +	if (ret)
> +		goto outd;
> +	resp_levels = tl->rx.buf;
> +
> +	for (dom = 0; dom < vinfo->num_domains; dom++) {
> +		u32 desc_index = 0;
> +		u16 num_returned = 0, num_remaining = 0;
> +		struct scmi_msg_cmd_describe_levels *cmd;
> +		struct scmi_voltage_info *v;
> +
> +		/* Retrieve domain attributes at first ... */
> +		put_unaligned_le32(dom, td->tx.buf);
> +		ret = scmi_do_xfer(handle, td);
> +		/* Skip domain on comms error */
> +		if (ret)
> +			continue;
> +
> +		v = devm_kzalloc(dev, sizeof(*v), GFP_KERNEL);
> +		if (!v) {
> +			ret = -ENOMEM;
> +			break;
> +		}
> +

Why can't we allocate vinfo->domains real structure instead of pointers
and indirection there ? I understand that it helps to manage holes easily
but I think that would simplify the dynamic allocation and error handling.
It doesn't have to be this complicated(not much but still) IMO.

May be scmi_voltage_info_get can use num_levels to either return NULL
or vinfo->domains[domain_id] ?

Regards,
Sudeep