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

[Etienne Carriere]

Hello Christian,

I faced an issue with this change, see below.

On Tue, 6 Oct 2020 at 00:26, Cristian Marussi <cristian.marussi@xxxxxxx> wrote:
>
> Add SCMI Voltage Domain protocol support.
>
> Signed-off-by: Cristian Marussi <cristian.marussi@xxxxxxx>
> ---
>  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 | 378 ++++++++++++++++++++++++++++
>  include/linux/scmi_protocol.h       |  64 +++++
>  5 files changed, 446 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 37fb583f1bf5..eaa4d0e1174f 100644
> --- a/drivers/firmware/arm_scmi/common.h
> +++ b/drivers/firmware/arm_scmi/common.h
> @@ -167,6 +167,7 @@ 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 c5dea87edf8f..d7f50bf5f958 100644
> --- a/drivers/firmware/arm_scmi/driver.c
> +++ b/drivers/firmware/arm_scmi/driver.c
> @@ -938,6 +938,7 @@ 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);
> @@ -953,6 +954,7 @@ 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..94221d979b80
> --- /dev/null
> +++ b/drivers/firmware/arm_scmi/voltage.c
> @@ -0,0 +1,378 @@
> +// 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;
> +
> +       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;
> +
> +               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;
> +               cmd->domain_id = cpu_to_le32(v->id);
> +               /* ...then retrieve domain levels descriptions */
> +               do {
> +                       u32 flags;
> +                       int cnt;
> +

Here domain_id must be reloaded in the message payload.

+               cmd->domain_id = cpu_to_le32(v->id);

When the SCMI shared memory is used as a unique buffer for
tx and rx messages, cmd refers to the memory storing previous
message sent on the SCMI channel.
In the loop we're in, the previous response has scratched
previous outgoing message including domain_id value hence
the full message sent to the SCMI server should be reloaded
before scmi_do_xfer() is called.

Regards,
etienne

> +                       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",
> +                                       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)
> +                                       v->negative_volts_allowed = true;
> +                       }
> +
> +                       desc_index += num_returned;
> +                       /* 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_xfer_put(handle, tl);
> +outd:
> +       scmi_xfer_put(handle, td);
> +
> +       return ret;
> +}
> +
> +static inline int __scmi_voltage_get_u32(const struct scmi_handle *handle,
> +                                        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
>