Re: [PATCH v2 1/4] firmware: arm_scmi: Add Voltage Domain Support

[Etienne Carriere]

Hello Cristian,

Thanks for the update.
Some minor comments below.
FYI I successfully tested this series.

Regards,
Etienne

On Thu, 15 Oct 2020 at 17:40, Cristian Marussi <cristian.marussi@xxxxxxx> wrote:
>
> Add SCMI Voltage Domain protocol support.
>
> Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> ---
> 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 | 382 ++++++++++++++++++++++++++++
>  include/linux/scmi_protocol.h       |  64 +++++
>  5 files changed, 450 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..a20da5128de1
> --- /dev/null
> +++ b/drivers/firmware/arm_scmi/voltage.c
> @@ -0,0 +1,382 @@
> +// 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)))
> +};
> +
> +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 {
> +       u32 version;
> +       u16 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 inline int scmi_init_voltage_levels(struct device *dev,
> +                                          struct scmi_voltage_info *v,
> +                                          u32 flags, u32 num_levels)
> +{
> +       bool segmented;
> +
> +       segmented = SUPPORTS_SEGMENTED_LEVELS(flags);
> +       /* segmented levels array's entries must be multiple-of-3 */
> +       if (!num_levels || (segmented && num_levels % 3))
> +               return -EINVAL;

I think segment levels are described by a single triplet.
If right, should test (!num_levels || (segmented && num_levels == 3)).


> +
> +       v->levels_uv = devm_kcalloc(dev, num_levels, sizeof(u32), GFP_KERNEL);
> +       if (!v->levels_uv)
> +               return -ENOMEM;
> +
> +       v->num_levels = num_levels;
> +       v->segmented = segmented;
> +
> +       return 0;
> +}
> +
> +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);
> +               if (ret)
> +                       continue;

Continue and break and report the error code?
Seems you prefer to abort only on local error (ENOMEM), not comm error.
Maybe state with nice inline comment as done below (/* Skip domain on error */).

> +
> +               v = devm_kzalloc(dev, sizeof(*v), GFP_KERNEL);
> +               if (!v) {
> +                       ret = -ENOMEM;
> +                       break;
> +               }
> +
> +               v->id = dom;
> +               v->attributes = le32_to_cpu(resp_dom->attr);
> +               strlcpy(v->name, resp_dom->name, SCMI_MAX_STR_SIZE);
> +
> +               cmd = tl->tx.buf;
> +               /* ...then retrieve domain levels descriptions */
> +               do {
> +                       u32 flags;
> +                       int cnt;
> +
> +                       cmd->domain_id = cpu_to_le32(v->id);
> +                       cmd->level_index = desc_index;
> +                       ret = scmi_do_xfer(handle, tl);
> +                       if (ret)
> +                               break;
> +
> +                       flags = le32_to_cpu(resp_levels->flags);
> +                       num_returned = NUM_RETURNED_LEVELS(flags);
> +                       num_remaining = NUM_REMAINING_LEVELS(flags);
> +
> +                       /* Allocate space for num_levels if not already done */
> +                       if (!v->num_levels) {
> +                               ret = scmi_init_voltage_levels(dev, v, flags,
> +                                                              num_returned +
> +                                                              num_remaining);
> +                               if (ret)
> +                                       break;
> +                       }
> +
> +                       if (desc_index + num_returned > v->num_levels) {
> +                               dev_err(handle->dev,
> +                                       "No. of voltage levels can't exceed %d",

Missing '\n'.

> +                                       v->num_levels);
> +                               ret = -EINVAL;
> +                               break;
> +                       }
> +
> +                       for (cnt = 0; cnt < num_returned; cnt++) {
> +                               s32 val;
> +
> +                               val =
> +                                   (s32)le32_to_cpu(resp_levels->voltage[cnt]);
> +                               v->levels_uv[desc_index + cnt] = val;
> +                               if (!v->negative_volts_allowed && val < 0)

could skip testing v->negative_volts_allowed.
        if (val < 0)
                v->negative_volts_allowed = true;


> +                                       v->negative_volts_allowed = true;
> +                       }
> +
> +                       desc_index += num_returned;
> +
> +                       scmi_reset_rx_to_maxsz(handle, tl);
> +                       /* check both to avoid infinite loop due to buggy fw */
> +               } while (num_returned && num_remaining);
> +
> +               /*
> +                * Bail out on memory errors, just skip domain on any
> +                * other error.
> +                */
> +               if (!ret)
> +                       vinfo->domains[dom] = v;
> +               else if (ret == -ENOMEM)
> +                       break;
> +
> +               scmi_reset_rx_to_maxsz(handle, td);
> +       }
> +
> +       scmi_xfer_put(handle, tl);
> +outd:
> +       scmi_xfer_put(handle, td);
> +
> +       return ret;
> +}
> +
> +static inline int __scmi_voltage_get_u32(const struct scmi_handle *handle,

inline needed ?

> +                                        u8 cmd_id, u32 domain_id, u32 *value)
> +{
> +       int ret;
> +       struct scmi_xfer *t;
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +
> +       if (domain_id >= vinfo->num_domains)
> +               return -EINVAL;
> +
> +       ret = scmi_xfer_get_init(handle, cmd_id,
> +                                SCMI_PROTOCOL_VOLTAGE,
> +                                sizeof(__le32), 0, &t);
> +       if (ret)
> +               return ret;
> +
> +       put_unaligned_le32(domain_id, t->tx.buf);
> +       ret = scmi_do_xfer(handle, t);
> +       if (!ret)
> +               *value = get_unaligned_le32(t->rx.buf);
> +
> +       scmi_xfer_put(handle, t);
> +       return ret;
> +}
> +
> +static int scmi_voltage_config_set(const struct scmi_handle *handle,
> +                                  u32 domain_id, u32 config)
> +{
> +       int ret;
> +       struct scmi_xfer *t;
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +       struct scmi_msg_cmd_config_set *cmd;
> +
> +       if (domain_id >= vinfo->num_domains)
> +               return -EINVAL;
> +
> +       ret = scmi_xfer_get_init(handle, VOLTAGE_CONFIG_SET,
> +                                SCMI_PROTOCOL_VOLTAGE,
> +                                sizeof(*cmd), 0, &t);
> +       if (ret)
> +               return ret;
> +
> +       cmd = t->tx.buf;
> +       cmd->domain_id = cpu_to_le32(domain_id);
> +       cmd->config = cpu_to_le32(config & GENMASK(3, 0));
> +
> +       ret = scmi_do_xfer(handle, t);
> +
> +       scmi_xfer_put(handle, t);
> +       return ret;
> +}
> +
> +static int scmi_voltage_config_get(const struct scmi_handle *handle,
> +                                  u32 domain_id, u32 *config)
> +{
> +       return __scmi_voltage_get_u32(handle, VOLTAGE_CONFIG_GET,
> +                                     domain_id, config);
> +}
> +
> +static int scmi_voltage_level_set(const struct scmi_handle *handle,
> +                                 u32 domain_id, u32 flags, s32 volt_uV)
> +{
> +       int ret;
> +       struct scmi_xfer *t;
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +       struct scmi_msg_cmd_level_set *cmd;
> +
> +       if (domain_id >= vinfo->num_domains)
> +               return -EINVAL;
> +
> +       ret = scmi_xfer_get_init(handle, VOLTAGE_LEVEL_SET,
> +                                SCMI_PROTOCOL_VOLTAGE,
> +                                sizeof(*cmd), 0, &t);
> +       if (ret)
> +               return ret;
> +
> +       cmd = t->tx.buf;
> +       cmd->domain_id = cpu_to_le32(domain_id);
> +       cmd->flags = cpu_to_le32(flags);
> +       cmd->voltage_level = cpu_to_le32(volt_uV);
> +
> +       ret = scmi_do_xfer(handle, t);
> +
> +       scmi_xfer_put(handle, t);
> +       return ret;
> +}
> +
> +static int scmi_voltage_level_get(const struct scmi_handle *handle,
> +                                 u32 domain_id, s32 *volt_uV)
> +{
> +       return __scmi_voltage_get_u32(handle, VOLTAGE_LEVEL_GET,
> +                                     domain_id, (u32 *)volt_uV);
> +}
> +
> +static const struct scmi_voltage_info *
> +scmi_voltage_info_get(const struct scmi_handle *handle, u32 domain_id)
> +{
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +
> +       if (domain_id >= vinfo->num_domains)
> +               return NULL;
> +
> +       return vinfo->domains[domain_id];
> +}
> +
> +static int scmi_voltage_domains_num_get(const struct scmi_handle *handle)
> +{
> +       struct voltage_info *vinfo = handle->voltage_priv;
> +
> +       return vinfo->num_domains;
> +}
> +
> +static struct scmi_voltage_ops voltage_ops = {
> +       .num_domains_get = scmi_voltage_domains_num_get,
> +       .info_get = scmi_voltage_info_get,
> +       .config_set = scmi_voltage_config_set,
> +       .config_get = scmi_voltage_config_get,
> +       .level_set = scmi_voltage_level_set,
> +       .level_get = scmi_voltage_level_get,
> +};
> +
> +static int scmi_voltage_protocol_init(struct scmi_handle *handle)
> +{
> +       int ret;
> +       u32 version;
> +       struct voltage_info *vinfo;
> +
> +       ret = scmi_version_get(handle, SCMI_PROTOCOL_VOLTAGE, &version);
> +       if (ret)
> +               return ret;
> +
> +       dev_dbg(handle->dev, "Voltage Version %d.%d\n",
> +               PROTOCOL_REV_MAJOR(version), PROTOCOL_REV_MINOR(version));
> +
> +       vinfo = devm_kzalloc(handle->dev, sizeof(*vinfo), GFP_KERNEL);
> +       if (!vinfo)
> +               return -ENOMEM;
> +       vinfo->version = version;
> +
> +       ret = scmi_protocol_attributes_get(handle, vinfo);
> +       if (ret)
> +               return ret;
> +
> +       if (vinfo->num_domains) {
> +               vinfo->domains = devm_kcalloc(handle->dev, vinfo->num_domains,
> +                                             sizeof(vinfo->domains),
> +                                             GFP_KERNEL);
> +               if (!vinfo->domains)
> +                       return -ENOMEM;
> +               ret = scmi_voltage_descriptors_get(handle, vinfo);
> +               if (ret)
> +                       return ret;
> +       } else {
> +               dev_warn(handle->dev, "No Voltage domains found.\n");
> +       }
> +
> +       handle->voltage_ops = &voltage_ops;
> +       handle->voltage_priv = vinfo;
> +
> +       return 0;
> +}
> +
> +DEFINE_SCMI_PROTOCOL_REGISTER_UNREGISTER(SCMI_PROTOCOL_VOLTAGE, voltage)
> diff --git a/include/linux/scmi_protocol.h b/include/linux/scmi_protocol.h
> index 9cd312a1ff92..032ad9bb2a53 100644
> --- a/include/linux/scmi_protocol.h
> +++ b/include/linux/scmi_protocol.h
> @@ -209,6 +209,64 @@ struct scmi_reset_ops {
>         int (*deassert)(const struct scmi_handle *handle, u32 domain);
>  };
>
> +/**
> + * struct scmi_voltage_info - describe one available SCMI Voltage Domain
> + *
> + * @id: the domain ID as advertised by the platform
> + * @segmented: defines the layout of the entries of array @levels_uv.
> + *            - when True the entries are to be interpreted as triplets,
> + *              each defining a segment representing a range of equally
> + *              space voltages: <lowest_volts>, <highest_volt>, <step_uV>
> + *            - when False the entries simply represent a single discrete
> + *              supported voltage level
> + * @negative_volts_allowed: True if any of the entries of @levels_uv represent
> + *                         a negative voltage.
> + * @attributes: represents Voltage Domain advertised attributes
> + * @name: name assigned to the Voltage Domain by platform
> + * @num_levels: number of total entries in @levels_uv.
> + * @levels_uv: array of entries describing the available voltage levels for
> + *            this domain.
> + */
> +struct scmi_voltage_info {
> +       u32 id;
> +       bool segmented;
> +#define SCMI_VOLTAGE_SEGMENT_LOW       0
> +#define SCMI_VOLTAGE_SEGMENT_HIGH      1
> +#define SCMI_VOLTAGE_SEGMENT_STEP      2
> +       bool negative_volts_allowed;
> +       u32 attributes;
> +       char name[SCMI_MAX_STR_SIZE];
> +       u16 num_levels;
> +       s32 *levels_uv;
> +};
> +
> +/**
> + * struct scmi_voltage_ops - represents the various operations provided
> + * by SCMI Voltage Protocol
> + *
> + * @num_domains_get: get the count of voltage domains provided by SCMI
> + * @info_get: get the information of the specified domain
> + * @config_set: set the config for the specified domain
> + * @config_get: get the config of the specified domain
> + * @level_set: set the voltage level for the specified domain
> + * @level_get: get the voltage level of the specified domain
> + */
> +struct scmi_voltage_ops {
> +       int (*num_domains_get)(const struct scmi_handle *handle);
> +       const struct scmi_voltage_info *(*info_get)
> +               (const struct scmi_handle *handle, u32 domain_id);
> +       int (*config_set)(const struct scmi_handle *handle, u32 domain_id,
> +                         u32 config);
> +#define        SCMI_VOLTAGE_ARCH_STATE_OFF             0x0
> +#define        SCMI_VOLTAGE_ARCH_STATE_ON              0x7
> +       int (*config_get)(const struct scmi_handle *handle, u32 domain_id,
> +                         u32 *config);
> +       int (*level_set)(const struct scmi_handle *handle, u32 domain_id,
> +                        u32 flags, s32 volt_uV);
> +       int (*level_get)(const struct scmi_handle *handle, u32 domain_id,
> +                        s32 *volt_uV);
> +};
> +
>  /**
>   * struct scmi_notify_ops  - represents notifications' operations provided by
>   * SCMI core
> @@ -262,6 +320,7 @@ struct scmi_notify_ops {
>   * @clk_ops: pointer to set of clock protocol operations
>   * @sensor_ops: pointer to set of sensor protocol operations
>   * @reset_ops: pointer to set of reset protocol operations
> + * @voltage_ops: pointer to set of voltage protocol operations
>   * @notify_ops: pointer to set of notifications related operations
>   * @perf_priv: pointer to private data structure specific to performance
>   *     protocol(for internal use only)
> @@ -273,6 +332,8 @@ struct scmi_notify_ops {
>   *     protocol(for internal use only)
>   * @reset_priv: pointer to private data structure specific to reset
>   *     protocol(for internal use only)
> + * @voltage_priv: pointer to private data structure specific to voltage
> + *     protocol(for internal use only)
>   * @notify_priv: pointer to private data structure specific to notifications
>   *     (for internal use only)
>   */
> @@ -284,6 +345,7 @@ struct scmi_handle {
>         const struct scmi_power_ops *power_ops;
>         const struct scmi_sensor_ops *sensor_ops;
>         const struct scmi_reset_ops *reset_ops;
> +       const struct scmi_voltage_ops *voltage_ops;
>         const struct scmi_notify_ops *notify_ops;
>         /* for protocol internal use */
>         void *perf_priv;
> @@ -291,6 +353,7 @@ struct scmi_handle {
>         void *power_priv;
>         void *sensor_priv;
>         void *reset_priv;
> +       void *voltage_priv;
>         void *notify_priv;
>         void *system_priv;
>  };
> @@ -303,6 +366,7 @@ enum scmi_std_protocol {
>         SCMI_PROTOCOL_CLOCK = 0x14,
>         SCMI_PROTOCOL_SENSOR = 0x15,
>         SCMI_PROTOCOL_RESET = 0x16,
> +       SCMI_PROTOCOL_VOLTAGE = 0x17,
>  };
>
>  enum scmi_system_events {
> --
> 2.17.1
>