Date:   Thu, 03 Jan 2019 15:08:33 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Henry Chen <henryc.chen@...iatek.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Rob Herring <robh+dt@...nel.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Viresh Kumar <vireshk@...nel.org>
Cc:     Mark Rutland <mark.rutland@....com>,
        Fan Chen <fan.chen@...iatek.com>,
        Weiyi Lu <weiyi.lu@...iatek.com>,
        James Liao <jamesjj.liao@...iatek.com>,
        Kees Cook <keescook@...omium.org>, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Henry Chen <henryc.chen@...iatek.com>
Subject: Re: [RFC RESEND PATCH 6/7] soc: mediatek: add MT8183 dvfsrc support

Quoting Henry Chen (2019-01-02 06:09:57)
> diff --git a/drivers/soc/mediatek/Kconfig b/drivers/soc/mediatek/Kconfig
> index a7d0667..f956f03 100644
> --- a/drivers/soc/mediatek/Kconfig
> +++ b/drivers/soc/mediatek/Kconfig
> @@ -12,6 +12,21 @@ config MTK_INFRACFG
>           INFRACFG controller contains various infrastructure registers not
>           directly associated to any device.
>  
> +config MTK_DVFSRC
> +       bool "MediaTek DVFSRC Support"
> +       depends on ARCH_MEDIATEK
> +       default ARCH_MEDIATEK
> +       select REGMAP

Why?

> +       select MTK_INFRACFG
> +       select PM_GENERIC_DOMAINS if PM

It doesn't depend on it?

> +       depends on MTK_SCPSYS
> +       help
> +         Say yes here to add support for the MediaTek DVFSRC found

Maybe you can spell out what the DVFSRC acronym means?

> +         on different MediaTek SoCs. The DVFSRC is a proprietary
> +         hardware which is used to collect all the requests from
> +         system and turn into the decision of minimum Vcore voltage
> +         and minimum DRAM frequency to fulfill those requests.
> +
>  config MTK_PMIC_WRAP
>         tristate "MediaTek PMIC Wrapper Support"
>         depends on RESET_CONTROLLER
> diff --git a/drivers/soc/mediatek/Makefile b/drivers/soc/mediatek/Makefile
> index 9dc6670..5c010b9 100644
> --- a/drivers/soc/mediatek/Makefile
> +++ b/drivers/soc/mediatek/Makefile
> @@ -1,3 +1,4 @@
> +obj-$(CONFIG_MTK_DVFSRC) += mtk-dvfsrc.o
>  obj-$(CONFIG_MTK_INFRACFG) += mtk-infracfg.o mtk-scpsys-ext.o
>  obj-$(CONFIG_MTK_PMIC_WRAP) += mtk-pmic-wrap.o
>  obj-$(CONFIG_MTK_SCPSYS) += mtk-scpsys.o
> diff --git a/drivers/soc/mediatek/mtk-dvfsrc.c b/drivers/soc/mediatek/mtk-dvfsrc.c
> new file mode 100644
> index 0000000..af462a3
> --- /dev/null
> +++ b/drivers/soc/mediatek/mtk-dvfsrc.c
> @@ -0,0 +1,473 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2018 MediaTek Inc.
> + */
> +#include <linux/arm-smccc.h>
> +#include <linux/clk.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/irq.h>

Presumably both interrupt.h and irq.h aren't needed.

> +#include <linux/delay.h>
> +#include <linux/kthread.h>

Is this used?

> +#include <linux/module.h>
> +#include <linux/notifier.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/pm_qos.h>
> +#include <linux/slab.h>
> +#include <linux/spinlock.h>

Is this used?

> +#include <soc/mediatek/mtk_sip.h>
> +#include <dt-bindings/power/mt8183-power.h>
> +#include <dt-bindings/soc/mtk,dvfsrc.h>
> +#include "mtk-scpsys.h"
> +
> +#define DVFSRC_IDLE            0x00
> +#define DVFSRC_GET_TARGET_LEVEL(x)     (((x) >> 0) & 0x0000ffff)
> +#define DVFSRC_GET_CURRENT_LEVEL(x)    (((x) >> 16) & 0x0000ffff)
> +
> +/* macro for irq */
> +#define DVFSRC_IRQ_TIMEOUT_EN          BIT(1)
> +
> +struct dvfsrc_opp {
> +       int vcore_opp;
> +       int dram_opp;
> +};
> +
> +struct dvfsrc_domain {
> +       int id;
> +       int state;

Does id or state need to be signed? Perhaps unsigned or u32 is better?

> +};
> +
> +struct mtk_dvfsrc;
> +struct dvfsrc_soc_data {
> +       const int *regs;
> +       int num_opp;
> +       int num_domains;
> +       int dram_sft;
> +       int vcore_sft;
> +       const struct dvfsrc_opp **opps;
> +       struct dvfsrc_domain *domains;
> +       void (*init_soc)(struct mtk_dvfsrc *dvfsrc);
> +       int (*get_target_level)(struct mtk_dvfsrc *dvfsrc);
> +       int (*get_current_level)(struct mtk_dvfsrc *dvfsrc);
> +};
> +
> +struct mtk_dvfsrc {
> +       struct device *dev;
> +       struct clk *clk_dvfsrc;
> +       const struct dvfsrc_soc_data *dvd;
> +       int dram_type;
> +       int irq;
> +       void __iomem *regs;
> +       struct mutex lock;      /* generic mutex for dvfsrc driver */

That's not a very useful comment. Please make it useful or remove it.

> +
> +       struct notifier_block qos_notifier;
> +       struct notifier_block scpsys_notifier;
> +};
> +
> +static u32 dvfsrc_read(struct mtk_dvfsrc *dvfs, u32 offset)
> +{
> +       return readl(dvfs->regs + dvfs->dvd->regs[offset]);
> +}
> +
> +static void dvfsrc_write(struct mtk_dvfsrc *dvfs, u32 offset, u32 val)
> +{
> +       writel(val, dvfs->regs + dvfs->dvd->regs[offset]);
> +}
> +
[...]
> +
> +static bool dvfsrc_is_idle(struct mtk_dvfsrc *dvfsrc)
> +{
> +       int val = 0;
> +
> +       if (dvfsrc->dvd->get_target_level)
> +               val = dvfsrc->dvd->get_target_level(dvfsrc);
> +
> +       return val == DVFSRC_IDLE;
> +}
> +
> +static int dvfsrc_wait_for_state(struct mtk_dvfsrc *dvfsrc,
> +                                bool (*fp)(struct mtk_dvfsrc *))

It's always dvfsrc_is_idle though, so why pass it as an argument?

> +{
> +       unsigned long timeout;
> +
> +       timeout = jiffies + usecs_to_jiffies(1000);
> +
> +       do {
> +               if (fp(dvfsrc))
> +                       return 0;
> +       } while (!time_after(jiffies, timeout));
> +
> +       return -ETIMEDOUT;
> +}
> +
> +static void mtk_dvfsrc_mt8183_init(struct mtk_dvfsrc *dvfsrc)
> +{
> +       struct arm_smccc_res res;
> +
> +       mutex_lock(&dvfsrc->lock);
> +
> +       arm_smccc_smc(MTK_SIP_SPM, MTK_SIP_SPM_DVFSRC_INIT, 0, 0, 0, 0, 0, 0,
> +                     &res);

What if that fails?

> +
> +       dvfsrc_write(dvfsrc, DVFSRC_LEVEL_LABEL_0_1, 0x00100000);
> +
> +       dvfsrc_write(dvfsrc, DVFSRC_LEVEL_LABEL_2_3, 0x00210011);
> +       dvfsrc_write(dvfsrc, DVFSRC_LEVEL_LABEL_4_5, 0x01100100);
> +       dvfsrc_write(dvfsrc, DVFSRC_LEVEL_LABEL_6_7, 0x01210111);
> +       dvfsrc_write(dvfsrc, DVFSRC_LEVEL_LABEL_8_9, 0x02100200);
> +       dvfsrc_write(dvfsrc, DVFSRC_LEVEL_LABEL_10_11, 0x02210211);
> +       dvfsrc_write(dvfsrc, DVFSRC_LEVEL_LABEL_12_13, 0x03210321);
> +       dvfsrc_write(dvfsrc, DVFSRC_LEVEL_LABEL_14_15, 0x03210321);
> +
> +       /* EMI/VCORE HRT, MD2SPM, BW setting */
> +       dvfsrc_write(dvfsrc, DVFSRC_EMI_QOS0, 0x32);
> +       dvfsrc_write(dvfsrc, DVFSRC_EMI_QOS1, 0x66);
> +       dvfsrc_write(dvfsrc, DVFSRC_EMI_MD2SPM0, 0x80F8);
> +       dvfsrc_write(dvfsrc, DVFSRC_EMI_MD2SPM1, 0x0);
> +       dvfsrc_write(dvfsrc, DVFSRC_VCORE_MD2SPM0, 0x80C0);
> +
> +       dvfsrc_write(dvfsrc, DVFSRC_RSRV_1, 0x0000001C);
> +       dvfsrc_write(dvfsrc, DVFSRC_TIMEOUT_NEXTREQ, 0x00000013);
> +       dvfsrc_write(dvfsrc, DVFSRC_INT_EN, 0x2);
> +
> +       dvfsrc_write(dvfsrc, DVFSRC_EMI_REQUEST, 0x00290209);
> +       dvfsrc_write(dvfsrc, DVFSRC_EMI_REQUEST2, 0);
> +
> +       dvfsrc_write(dvfsrc, DVFSRC_VCORE_REQUEST, 0x00150000);
> +
> +       dvfsrc_write(dvfsrc, DVFSRC_QOS_EN, 0x0000407F);
> +       dvfsrc_write(dvfsrc, DVFSRC_EMI_REQUEST3, 0x09000000);
> +
> +       dvfsrc_write(dvfsrc, DVFSRC_FORCE, 0x00400000);
> +       dvfsrc_write(dvfsrc, DVFSRC_BASIC_CONTROL, 0x0000C07B);
> +       dvfsrc_write(dvfsrc, DVFSRC_BASIC_CONTROL, 0x0000017B);
> +
> +       dvfsrc_write(dvfsrc, DVFSRC_VCORE_REQUEST,
> +                    (dvfsrc_read(dvfsrc, DVFSRC_VCORE_REQUEST)
> +                    & ~(0x3 << 20)));
> +       dvfsrc_write(dvfsrc, DVFSRC_EMI_REQUEST,
> +                    (dvfsrc_read(dvfsrc, DVFSRC_EMI_REQUEST)
> +                    & ~(0x3 << 20)));

Use some local variables so you don't read inside a write and make long
lines.

> +
> +       mutex_unlock(&dvfsrc->lock);
> +}
> +
> +static int mt8183_get_target_level(struct mtk_dvfsrc *dvfsrc)
> +{
> +       return DVFSRC_GET_TARGET_LEVEL(dvfsrc_read(dvfsrc, DVFSRC_LEVEL));
> +}
> +
> +static int mt8183_get_current_level(struct mtk_dvfsrc *dvfsrc)
> +{
> +       return DVFSRC_GET_CURRENT_LEVEL(dvfsrc_read(dvfsrc, DVFSRC_LEVEL));
> +}
> +
> +static int get_cur_performance_level(struct mtk_dvfsrc *dvfsrc)
> +{
> +       int bit = 0;
> +
> +       if (dvfsrc->dvd->get_current_level)
> +               bit = dvfsrc->dvd->get_current_level(dvfsrc);
> +
> +       return ffs(bit);
> +}
> +
> +static int pm_qos_memory_bw_notify(struct notifier_block *b,
> +                                  unsigned long bw, void *v)
> +{
> +       struct mtk_dvfsrc *dvfsrc;
> +
> +       dvfsrc = container_of(b, struct mtk_dvfsrc, qos_notifier);
> +       mutex_lock(&dvfsrc->lock);
> +
> +       dev_dbg(dvfsrc->dev, "data: 0x%lx\n", bw);
> +       dvfsrc_write(dvfsrc, DVFSRC_SW_BW_0, bw / 100);
> +
> +       mutex_unlock(&dvfsrc->lock);
> +
> +       return NOTIFY_OK;
> +}
> +
> +static int dvfsrc_set_performace(struct notifier_block *b,
> +                                unsigned long l, void *v)
> +{
> +       int i, val, highest = 0, vcore_opp = 0, dram_opp = 0;
> +       struct mtk_dvfsrc *dvfsrc;
> +       struct scp_event_data *sc = v;
> +       struct dvfsrc_domain *d;
> +
> +       if (sc->event_type != MTK_SCPSYS_PSTATE)
> +               return 0;
> +
> +       dvfsrc = container_of(b, struct mtk_dvfsrc, scpsys_notifier);
> +
> +       mutex_lock(&dvfsrc->lock);
> +       d = dvfsrc->dvd->domains;
> +
> +       if (l > dvfsrc->dvd->num_opp || l <= 0) {

How can l be < 0? It's unsigned.

> +               dev_err(dvfsrc->dev, "pstate out of range = %ld\n", l);
> +               goto out;
> +       }
> +
> +       for (i = 0, highest = 0; i < dvfsrc->dvd->num_domains - 1; i++, d++) {
> +               if (sc->domain_id == d->id)
> +                       d->state = l;
> +               if (d->state > highest)
> +                       highest = d->state;
> +       }
> +
> +       if (highest == 0) {
> +               dev_err(dvfsrc->dev, "domain not match\n");
> +               goto out;
> +       }
> +
> +       /* translate pstate to dvfsrc level, and set it to DVFSRC HW */
> +       vcore_opp =
> +               dvfsrc->dvd->opps[dvfsrc->dram_type][highest - 1].vcore_opp;
> +       dram_opp = dvfsrc->dvd->opps[dvfsrc->dram_type][highest - 1].dram_opp;

Maybe make a local variable for

	dvfsrc->dvd->opps[dvfsrc->dram_type][highest - 1]

so you don't have to read that more than once.

> +
> +       if (dvfsrc_wait_for_state(dvfsrc, dvfsrc_is_idle)) {
> +               dev_warn(dvfsrc->dev, "[%s] wait idle, last: %d -> %d\n",
> +                        __func__, dvfsrc_read(dvfsrc, DVFSRC_LEVEL),
> +               dvfsrc_read(dvfsrc, DVFSRC_LAST));
> +               goto out;
> +       }
> +
> +       dvfsrc_write(dvfsrc, DVFSRC_SW_REQ,
> +                    dram_opp << dvfsrc->dvd->dram_sft |
> +                    vcore_opp << dvfsrc->dvd->vcore_sft);
> +
> +       if (dvfsrc_wait_for_state(dvfsrc, dvfsrc_is_idle)) {
> +               dev_warn(dvfsrc->dev, "[%s] wait idle, last: %d -> %d\n",
> +                        __func__, dvfsrc_read(dvfsrc, DVFSRC_LEVEL),
> +                        dvfsrc_read(dvfsrc, DVFSRC_LAST));
> +               goto out;
> +       }
> +
> +       val = get_cur_performance_level(dvfsrc);
> +       if (val < highest) {
> +               dev_err(dvfsrc->dev, "current: %d < hightest: %x\n",
> +                       highest, val);
> +       }
> +out:
> +       mutex_unlock(&dvfsrc->lock);
> +
> +       return 0;
> +}
> +
> +static void pstate_notifier_register(struct mtk_dvfsrc *dvfsrc)
> +{
> +       dvfsrc->scpsys_notifier.notifier_call = dvfsrc_set_performace;
> +       register_scpsys_notifier(&dvfsrc->scpsys_notifier);
> +}
> +
> +static void pm_qos_notifier_register(struct mtk_dvfsrc *dvfsrc)
> +{
> +       dvfsrc->qos_notifier.notifier_call = pm_qos_memory_bw_notify;
> +       pm_qos_add_notifier(PM_QOS_MEMORY_BANDWIDTH, &dvfsrc->qos_notifier);
> +}
> +
> +static irqreturn_t mtk_dvfsrc_interrupt(int irq, void *dev_id)
> +{
> +       u32 val;
> +       struct mtk_dvfsrc *dvfsrc = dev_id;
> +
> +       val = dvfsrc_read(dvfsrc, DVFSRC_INT);
> +       dvfsrc_write(dvfsrc, DVFSRC_INT_CLR, val);
> +       dvfsrc_write(dvfsrc, DVFSRC_INT_CLR, 0x0);
> +       if (val & DVFSRC_IRQ_TIMEOUT_EN)
> +               dev_warn(dvfsrc->dev, "timeout at spm = %x", val);
> +

Do you need to handle the irq at all? It looks like you are cleaning up
something and then complaining if there's a timeout, but otherwise
nothing goes on so perhaps the irq can just be ignored and nobody will
be the wiser?

> +       return IRQ_HANDLED;
> +}
> +
> +static int mtk_dvfsrc_probe(struct platform_device *pdev)
> +{
> +       struct resource *res;
> +       struct mtk_dvfsrc *dvfsrc;
> +       int ret;
> +
> +       dvfsrc = devm_kzalloc(&pdev->dev, sizeof(*dvfsrc), GFP_KERNEL);
> +       if (!dvfsrc)
> +               return -ENOMEM;
> +
> +       dvfsrc->dvd = of_device_get_match_data(&pdev->dev);
> +       dvfsrc->dev = &pdev->dev;
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       dvfsrc->regs = devm_ioremap_resource(&pdev->dev, res);
> +       if (IS_ERR(dvfsrc->regs))
> +               return PTR_ERR(dvfsrc->regs);
> +
> +       dvfsrc->clk_dvfsrc = devm_clk_get(dvfsrc->dev, "dvfsrc");
> +       if (IS_ERR(dvfsrc->clk_dvfsrc)) {
> +               dev_err(dvfsrc->dev, "failed to get clock: %ld\n",
> +                       PTR_ERR(dvfsrc->clk_dvfsrc));
> +               return PTR_ERR(dvfsrc->clk_dvfsrc);
> +       }
> +
> +       ret = clk_prepare_enable(dvfsrc->clk_dvfsrc);
> +       if (ret)
> +               return ret;
> +
> +       ret = of_property_read_u32(dvfsrc->dev->of_node, "dram_type",
> +                                  &dvfsrc->dram_type);
> +       if (ret) {
> +               dev_err(dvfsrc->dev, "failed to get dram_type: %d\n", ret);
> +               clk_disable_unprepare(dvfsrc->clk_dvfsrc);

Why do you need to enable the clk before reading a DT property? Do that
first and then enable the clk so you don't have to unwind it here?

> +               return ret;
> +       }
> +
> +       dvfsrc->irq = platform_get_irq(pdev, 0);
> +       ret = request_irq(dvfsrc->irq, mtk_dvfsrc_interrupt
> +               , IRQF_TRIGGER_HIGH, "dvfsrc", dvfsrc);

Nitpick: This is oddly placed comma.

> +       if (ret)
> +               dev_dbg(dvfsrc->dev, "interrupt not use\n");
> +
> +       mutex_init(&dvfsrc->lock);
> +       if (dvfsrc->dvd->init_soc)
> +               dvfsrc->dvd->init_soc(dvfsrc);
> +
> +       pstate_notifier_register(dvfsrc);
> +       pm_qos_notifier_register(dvfsrc);
> +       platform_set_drvdata(pdev, dvfsrc);

Probably should assign the platform data before anything can use it,
including notifiers?

> +
> +       return 0;
> +}
> +
> +static const struct dvfsrc_opp dvfsrc_opp_mt8183_lp4[] = {
> +       {0, 0}, {1, 0}, {1, 1}, {1, 2},
> +};
> +
> +static const struct dvfsrc_opp dvfsrc_opp_mt8183_1p3[] = {
> +       {0, 0}, {0, 1}, {1, 1}, {1, 2},
> +};
> +
> +static const struct dvfsrc_opp *dvfsrc_opp_mt8183[] = {
> +       [MT8183_DVFSRC_OPP_LP4] = dvfsrc_opp_mt8183_lp4,
> +       [MT8183_DVFSRC_OPP_LP4X] = dvfsrc_opp_mt8183_1p3,
> +       [MT8183_DVFSRC_OPP_LP3] = dvfsrc_opp_mt8183_1p3,
> +};
> +
> +static struct dvfsrc_domain dvfsrc_domains_mt8183[] = {
> +       {MT8183_POWER_DOMAIN_MFG_ASYNC, 0},

Nitpick: Put a space around { and }

> +       {MT8183_POWER_DOMAIN_MFG, 0},
> +       {MT8183_POWER_DOMAIN_CAM, 0},
> +       {MT8183_POWER_DOMAIN_DISP, 0},
> +       {MT8183_POWER_DOMAIN_ISP, 0},
> +       {MT8183_POWER_DOMAIN_VDEC, 0},
> +       {MT8183_POWER_DOMAIN_VENC, 0},
> +};
> +
> +static const struct dvfsrc_soc_data mt8183_data = {
> +       .opps = dvfsrc_opp_mt8183,
> +       .num_opp = ARRAY_SIZE(dvfsrc_opp_mt8183_lp4),
> +       .regs = mt8183_regs,
> +       .domains = dvfsrc_domains_mt8183,
> +       .num_domains = ARRAY_SIZE(dvfsrc_domains_mt8183),
> +       .init_soc = mtk_dvfsrc_mt8183_init,
> +       .get_target_level = mt8183_get_target_level,
> +       .get_current_level = mt8183_get_current_level,
> +       .dram_sft = 0,
> +       .vcore_sft = 2,
> +};
> +
> +static int mtk_dvfsrc_remove(struct platform_device *pdev)
> +{
> +       return 0;
> +}

You can just leave it out if it does nothing.

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