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Subject: Re: [PATCH v4 2/4] interconnect: qcom: Add OSM L3 interconnect
 provider support
To:     Sibi Sankar <sibis@codeaurora.org>,
        Evan Green <evgreen@chromium.org>
Cc:     Rob Herring <robh+dt@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Andy Gross <agross@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" 
        <devicetree@vger.kernel.org>,
        linux-arm-msm <linux-arm-msm@vger.kernel.org>,
        Mark Rutland <mark.rutland@arm.com>,
        David Dai <daidavid1@codeaurora.org>,
        Saravana Kannan <saravanak@google.com>,
        Viresh Kumar <viresh.kumar@linaro.org>
References: <20200109211215.18930-1-sibis@codeaurora.org>
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From:   Georgi Djakov <georgi.djakov@linaro.org>
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Message-ID: <03f83755-bdcc-dc39-0eae-08414751be57@linaro.org>
Date:   Wed, 22 Jan 2020 10:19:58 +0200
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On 1/22/20 08:45, Sibi Sankar wrote:
> Hey Evan,
> 
> Thanks for the review!
> 
> On 2020-01-22 03:03, Evan Green wrote:
>> On Thu, Jan 9, 2020 at 1:12 PM Sibi Sankar <sibis@codeaurora.org> wrote:
>>>
>>> On some Qualcomm SoCs, Operating State Manager (OSM) controls the
>>> resources of scaling L3 caches. Add a driver to handle bandwidth
>>> requests to OSM L3 from CPU on SDM845 SoCs.
>>>
>>> Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
>>> ---
>>>  drivers/interconnect/qcom/Kconfig  |   7 +
>>>  drivers/interconnect/qcom/Makefile |   2 +
>>>  drivers/interconnect/qcom/osm-l3.c | 267 +++++++++++++++++++++++++++++
>>>  3 files changed, 276 insertions(+)
>>>  create mode 100644 drivers/interconnect/qcom/osm-l3.c
>>>
>>> diff --git a/drivers/interconnect/qcom/Kconfig
>>> b/drivers/interconnect/qcom/Kconfig
>>> index a9bbbdf7400f9..b94d28e7bf700 100644
>>> --- a/drivers/interconnect/qcom/Kconfig
>>> +++ b/drivers/interconnect/qcom/Kconfig
>>> @@ -14,6 +14,13 @@ config INTERCONNECT_QCOM_MSM8974
>>>          This is a driver for the Qualcomm Network-on-Chip on msm8974-based
>>>          platforms.
>>>
>>> +config INTERCONNECT_QCOM_OSM_L3
>>> +       tristate "Qualcomm OSM L3 interconnect driver"
>>> +       depends on INTERCONNECT_QCOM || COMPILE_TEST
>>> +       help
>>> +         Say y here to support the Operating State Manager (OSM) interconnect
>>> +         driver which controls the scaling of L3 caches on Qualcomm SoCs.
>>> +
>>>  config INTERCONNECT_QCOM_QCS404
>>>         tristate "Qualcomm QCS404 interconnect driver"
>>>         depends on INTERCONNECT_QCOM
>>> diff --git a/drivers/interconnect/qcom/Makefile
>>> b/drivers/interconnect/qcom/Makefile
>>> index 55ec3c5c89dbd..89fecbd1257c7 100644
>>> --- a/drivers/interconnect/qcom/Makefile
>>> +++ b/drivers/interconnect/qcom/Makefile
>>> @@ -1,5 +1,6 @@
>>>  # SPDX-License-Identifier: GPL-2.0
>>>
>>> +icc-osm-l3-objs                                := osm-l3.o
>>>  qnoc-msm8974-objs                      := msm8974.o
>>>  qnoc-qcs404-objs                       := qcs404.o
>>>  qnoc-sc7180-objs                       := sc7180.o
>>> @@ -12,6 +13,7 @@ icc-smd-rpm-objs                      := smd-rpm.o
>>>  obj-$(CONFIG_INTERCONNECT_QCOM_BCM_VOTER) += icc-bcm-voter.o
>>>  obj-$(CONFIG_INTERCONNECT_QCOM_MSM8916) += qnoc-msm8916.o
>>>  obj-$(CONFIG_INTERCONNECT_QCOM_MSM8974) += qnoc-msm8974.o
>>> +obj-$(CONFIG_INTERCONNECT_QCOM_OSM_L3) += icc-osm-l3.o
>>>  obj-$(CONFIG_INTERCONNECT_QCOM_QCS404) += qnoc-qcs404.o
>>>  obj-$(CONFIG_INTERCONNECT_QCOM_RPMH) += icc-rpmh.o
>>>  obj-$(CONFIG_INTERCONNECT_QCOM_SC7180) += qnoc-sc7180.o
>>> diff --git a/drivers/interconnect/qcom/osm-l3.c
>>> b/drivers/interconnect/qcom/osm-l3.c
>>> new file mode 100644
>>> index 0000000000000..7fde53c70081e
>>> --- /dev/null
>>> +++ b/drivers/interconnect/qcom/osm-l3.c
>>> @@ -0,0 +1,267 @@
>>> +// SPDX-License-Identifier: GPL-2.0
>>> +/*
>>> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
>>> + *
>>> + */
>>> +
>>> +#include <dt-bindings/interconnect/qcom,osm-l3.h>
>>> +#include <linux/bitfield.h>
>>> +#include <linux/clk.h>
>>> +#include <linux/interconnect-provider.h>
>>> +#include <linux/io.h>
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/of_device.h>
>>> +#include <linux/of_platform.h>
>>> +#include <linux/platform_device.h>
>>> +
>>> +#define LUT_MAX_ENTRIES                        40U
>>> +#define LUT_SRC                                GENMASK(31, 30)
>>> +#define LUT_L_VAL                      GENMASK(7, 0)
>>> +#define LUT_ROW_SIZE                   32
>>> +#define CLK_HW_DIV                     2
>>> +
>>> +/* Register offsets */
>>> +#define REG_ENABLE                     0x0
>>> +#define REG_FREQ_LUT                   0x110
>>> +#define REG_PERF_STATE                 0x920
>>> +
>>> +#define OSM_L3_MAX_LINKS               1
>>> +#define SDM845_MAX_RSC_NODES           130
>>
>> I'm nervous this define is going to fall out of date with
>> qcom,sdm845.h. I'm worried someone will end up adding a few more nodes
>> that were always there but previously hidden from Linux. Can we put
>> this define in include/dt-bindings/interconnect/qcom,sdm845.h, so at
>> least when that happens they'll come face to face with this define?
>> The same comment goes for the SC7180 define in patch 4.
> 
> Yeah both solution require manual
> intervention how about we just go
> with what I proposed below.
> 
>>
>> On second thought, this trick only works once. Are we sure there
>> aren't going to be other drivers that might want to tag on
>> interconnect nodes as well? How about instead we just add the enum
>> values below in qcom,sdm845.h as defines?
> 
> Georgi/Evan,
> Since qcom,sdm845.h is specific to
> bindings shouldn't I just create a
> .h file with all the enums so that
> it can used across all icc providers
> on SDM845?

This sounds good to me, unless Evan has any objections.

Thanks,
Georgi