Re: [PATCH v2 05/18] firmware: arm_scmi: add initial support for performance protocol

[Julien Thierry <julien.thierry@arm.com>]

On 05/09/17 16:04, Julien Thierry wrote:
> Hi Sudeep,
> 
> On 04/08/17 15:31, Sudeep Holla wrote:
>> The performance protocol is intended for the performance management of
>> group(s) of device(s) that run in the same performance domain. It
>> includes even the CPUs. A performance domain is defined by a set of
>> devices that always have to run at the same performance level.
>> For example, a set of CPUs that share a voltage domain, and have a
>> common frequency control, is said to be in the same performance domain.
>>
>> The commands in this protocol provide functionality to describe the
>> protocol version, describe various attribute flags, set and get the
>> performance level of a domain. It also supports discovery of the list
>> of performance levels supported by a performance domain, and the
>> properties of each performance level.
>>
>> This patch adds basic support for the performance protocol.
>>
>> Cc: Arnd Bergmann <arnd@arndb.de>
>> Signed-off-by: Sudeep Holla <sudeep.holla@arm.com>
>> ---
>>   drivers/firmware/arm_scmi/Makefile |   2 +-
>>   drivers/firmware/arm_scmi/common.h |   1 +
>>   drivers/firmware/arm_scmi/perf.c   | 511 
>> +++++++++++++++++++++++++++++++++++++
>>   include/linux/scmi_protocol.h      |  31 +++
>>   4 files changed, 544 insertions(+), 1 deletion(-)
>>   create mode 100644 drivers/firmware/arm_scmi/perf.c
>>
>> diff --git a/drivers/firmware/arm_scmi/Makefile 
>> b/drivers/firmware/arm_scmi/Makefile
>> index 21d01d1d6b9c..159de726ee45 100644
>> --- a/drivers/firmware/arm_scmi/Makefile
>> +++ b/drivers/firmware/arm_scmi/Makefile
>> @@ -1,2 +1,2 @@
>>   obj-$(CONFIG_ARM_SCMI_PROTOCOL)    = arm_scmi.o
>> -arm_scmi-y = base.o driver.o
>> +arm_scmi-y = base.o driver.o perf.o
>> diff --git a/drivers/firmware/arm_scmi/common.h 
>> b/drivers/firmware/arm_scmi/common.h
>> index e3fe5d9acc82..7473dfcad4ee 100644
>> --- a/drivers/firmware/arm_scmi/common.h
>> +++ b/drivers/firmware/arm_scmi/common.h
>> @@ -30,6 +30,7 @@
>>   #define PROTOCOL_REV_MAJOR(x)    ((x) >> PROTOCOL_REV_MINOR_BITS)
>>   #define PROTOCOL_REV_MINOR(x)    ((x) & PROTOCOL_REV_MINOR_MASK)
>>   #define MAX_PROTOCOLS_IMP    16
>> +#define MAX_OPPS        16
>>   enum scmi_std_protocol {
>>       SCMI_PROTOCOL_BASE = 0x10,
>> diff --git a/drivers/firmware/arm_scmi/perf.c 
>> b/drivers/firmware/arm_scmi/perf.c
>> new file mode 100644
>> index 000000000000..13d84d829201
>> --- /dev/null
>> +++ b/drivers/firmware/arm_scmi/perf.c
>> @@ -0,0 +1,511 @@
>> +/*
>> + * System Control and Management Interface (SCMI) Performance Protocol
>> + *
>> + * Copyright (C) 2017 ARM Ltd.
>> + *
>> + * This program is free software; you can redistribute it and/or 
>> modify it
>> + * under the terms and conditions of the GNU General Public License,
>> + * version 2, as published by the Free Software Foundation.
>> + *
>> + * This program is distributed in the hope it will be useful, but 
>> WITHOUT
>> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
>> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public 
>> License for
>> + * more details.
>> + *
>> + * You should have received a copy of the GNU General Public License 
>> along
>> + * with this program. If not, see <http://www.gnu.org/licenses/>.
>> + */
>> +
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_opp.h>
>> +#include <linux/sort.h>
>> +
>> +#include "common.h"
>> +
>> +enum scmi_performance_protocol_cmd {
>> +    PERF_DOMAIN_ATTRIBUTES = 0x3,
>> +    PERF_DESCRIBE_LEVELS = 0x4,
>> +    PERF_LIMITS_SET = 0x5,
>> +    PERF_LIMITS_GET = 0x6,
>> +    PERF_LEVEL_SET = 0x7,
>> +    PERF_LEVEL_GET = 0x8,
>> +    PERF_NOTIFY_LIMITS = 0x9,
>> +    PERF_NOTIFY_LEVEL = 0xa,
>> +};
>> +
>> +struct scmi_opp {
>> +    u32 perf;
>> +    u32 power;
>> +    u32 trans_latency_us;
>> +};
>> +
>> +struct scmi_msg_resp_perf_attributes {
>> +    __le16 num_domains;
>> +    __le16 flags;
>> +#define POWER_SCALE_IN_MILLIWATT(x)    ((x) & BIT(0))
>> +    __le32 stats_addr_low;
>> +    __le32 stats_addr_high;
>> +    __le32 stats_size;
>> +};
>> +
>> +struct scmi_msg_resp_perf_domain_attributes {
>> +    __le32 flags;
>> +#define SUPPORTS_SET_LIMITS(x)        ((x) & BIT(31))
>> +#define SUPPORTS_SET_PERF_LVL(x)    ((x) & BIT(30))
>> +#define SUPPORTS_PERF_LIMIT_NOTIFY(x)    ((x) & BIT(29))
>> +#define SUPPORTS_PERF_LEVEL_NOTIFY(x)    ((x) & BIT(28))
>> +    __le32 rate_limit_us;
>> +    __le32 sustained_freq_khz;
>> +    __le32 sustained_perf_level;
>> +        u8 name[SCMI_MAX_STR_SIZE];
>> +};
>> +
>> +struct scmi_msg_perf_describe_levels {
>> +    __le32 domain;
>> +    __le32 level_index;
>> +};
>> +
>> +struct scmi_perf_set_limits {
>> +    __le32 domain;
>> +    __le32 max_level;
>> +    __le32 min_level;
>> +};
>> +
>> +struct scmi_perf_get_limits {
>> +    __le32 max_level;
>> +    __le32 min_level;
>> +};
>> +
>> +struct scmi_perf_set_level {
>> +    __le32 domain;
>> +    __le32 level;
>> +};
>> +
>> +struct scmi_perf_notify_level_or_limits {
>> +    __le32 domain;
>> +    __le32 notify_enable;
>> +};
>> +
>> +struct scmi_msg_resp_perf_describe_levels {
>> +    __le16 num_returned;
>> +    __le16 num_remaining;
>> +    struct {
>> +        __le32 perf_val;
>> +        __le32 power;
>> +        __le16 transition_latency_us;
>> +        __le16 reserved;
>> +    } opp[0];
>> +};
>> +
>> +struct perf_dom_info {
>> +    bool set_limits;
>> +    bool set_perf;
>> +    bool perf_limit_notify;
>> +    bool perf_level_notify;
>> +    u32 opp_count;
>> +    u32 sustained_freq_khz;
>> +    u32 sustained_perf_level;
>> +    u32 mult_factor;
>> +    char name[SCMI_MAX_STR_SIZE];
>> +    struct scmi_opp opp[MAX_OPPS];
>> +};
>> +
>> +struct scmi_perf_info {
>> +    int num_domains;
>> +    bool power_scale_mw;
>> +    u64 stats_addr;
>> +    u32 stats_size;
>> +    struct perf_dom_info *dom_info;
>> +};
>> +
>> +static struct scmi_perf_info perf_info;
>> +
>> +static int scmi_perf_attributes_get(const struct scmi_handle *handle,
>> +                    struct scmi_perf_info *perf_info)
>> +{
>> +    int ret;
>> +    struct scmi_xfer *t;
>> +    struct scmi_msg_resp_perf_attributes *attr;
>> +
>> +    ret = scmi_one_xfer_init(handle, PROTOCOL_ATTRIBUTES,
>> +                 SCMI_PROTOCOL_PERF, 0, sizeof(*attr), &t);
>> +    if (ret)
>> +        return ret;
>> +
>> +    attr = t->rx.buf;
>> +
>> +    ret = scmi_do_xfer(handle, t);
>> +    if (!ret) {
>> +        u16 flags = le16_to_cpu(attr->flags);
>> +
>> +        perf_info->num_domains = le16_to_cpu(attr->num_domains);
>> +        perf_info->power_scale_mw = POWER_SCALE_IN_MILLIWATT(flags);
>> +        perf_info->stats_addr = le32_to_cpu(attr->stats_addr_low) |
>> +                (u64)le32_to_cpu(attr->stats_addr_high) << 32;
> 
> This seems odd, shouldn't it be the following?
> le64_to_cpu(attr->stats_addr_low | (__le64)attr->stats_addr_high << 32)
> 

After further reflexion, I think you are right. If I understood the 
specification, the address seems to be split into upper and lower 32bits 
and each one is stored as a uint32, which fits what you are doing to 
obtain the address.

You can ignore my previous comment.

-- 
Julien Thierry