Subject: Re: [PATCH v5 10/14] soc: mediatek: Add multiple step bus protection control

From: Weiyi Lu <[email-masked]>
Date: Wed, 19 Jun 2019 17:43:42 +0800

On Thu, 2019-03-21 at 13:57 +0800, Nicolas Boichat wrote:
> On Tue, Mar 19, 2019 at 4:02 PM Weiyi Lu <[email-masked]> wrote:
> >
> > Both MT8183 & MT6765 have more control steps of bus protection
> > than previous project. And there add more bus protection registers
> > reside at infracfg & smi-common. Also add new APIs for multiple
> > step bus protection control with more customize arguments.
> >
> > Signed-off-by: Weiyi Lu <[email-masked]>
> > ---
> >  drivers/soc/mediatek/Makefile           |  2 +-
> >  drivers/soc/mediatek/mtk-scpsys-ext.c   | 99 +++++++++++++++++++++++++
> >  drivers/soc/mediatek/mtk-scpsys.c       | 24 ++++++
> >  include/linux/soc/mediatek/scpsys-ext.h | 39 ++++++++++
> >  4 files changed, 163 insertions(+), 1 deletion(-)
> >  create mode 100644 drivers/soc/mediatek/mtk-scpsys-ext.c
> >  create mode 100644 include/linux/soc/mediatek/scpsys-ext.h
> >
> > diff --git a/drivers/soc/mediatek/Makefile b/drivers/soc/mediatek/Makefile
> > index 64ce5eeaba32..b9dbad6b12f9 100644
> > --- a/drivers/soc/mediatek/Makefile
> > +++ b/drivers/soc/mediatek/Makefile
> > @@ -1,4 +1,4 @@
> >  obj-$(CONFIG_MTK_CMDQ) += mtk-cmdq-helper.o
> > -obj-$(CONFIG_MTK_INFRACFG) += mtk-infracfg.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-scpsys-ext.c b/drivers/soc/mediatek/mtk-scpsys-ext.c
> > new file mode 100644
> > index 000000000000..f630edb2f65d
> > --- /dev/null
> > +++ b/drivers/soc/mediatek/mtk-scpsys-ext.c
> > @@ -0,0 +1,99 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (c) 2018 MediaTek Inc.
> > + * Author: Owen Chen <[email-masked]>
> > + */
> > +#include <linux/ktime.h>
> > +#include <linux/mfd/syscon.h>
> > +#include <linux/of_device.h>
> > +#include <linux/regmap.h>
> > +#include <linux/soc/mediatek/scpsys-ext.h>
> > +
> > +#define MTK_POLL_DELAY_US   10
> > +#define MTK_POLL_TIMEOUT    USEC_PER_SEC
> > +
> > +static int set_bus_protection(struct regmap *map, u32 mask, u32 ack_mask,
> > +               u32 reg_set, u32 reg_sta, u32 reg_en)
> > +{
> > +       u32 val;
> > +
> > +       if (reg_set)
> > +               regmap_write(map, reg_set, mask);
> > +       else
> > +               regmap_update_bits(map, reg_en, mask, mask);
> > +
> > +       return regmap_read_poll_timeout(map, reg_sta,
> > +                       val, (val & ack_mask) == ack_mask,
> > +                       MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> > +}
> > +
> > +static int clear_bus_protection(struct regmap *map, u32 mask, u32 ack_mask,
> > +               u32 reg_clr, u32 reg_sta, u32 reg_en)
> > +{
> > +       u32 val;
> > +
> > +       if (reg_clr)
> > +               regmap_write(map, reg_clr, mask);
> > +       else
> > +               regmap_update_bits(map, reg_en, mask, 0);
> > +
> > +       return regmap_read_poll_timeout(map, reg_sta,
> > +                       val, !(val & ack_mask),
> > +                       MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> > +}
> > +
> > +int mtk_scpsys_ext_set_bus_protection(const struct bus_prot *bp_table,
> > +       struct regmap *infracfg, struct regmap *smi_common)
> > +{
> > +       int i;
> > +
> > +       for (i = 0; i < MAX_STEPS && bp_table[i].mask; i++) {
> > +               struct regmap *map;
> > +               int ret;
> > +
> > +               if (bp_table[i].type == IFR_TYPE)
> > +                       map = infracfg;
> > +               else if (bp_table[i].type == SMI_TYPE)
> > +                       map = smi_common;
> > +               else
> > +                       return -EINVAL;
> > +
> > +               ret = set_bus_protection(map,
> > +                               bp_table[i].mask, bp_table[i].mask,
> > +                               bp_table[i].set_ofs, bp_table[i].sta_ofs,
> > +                               bp_table[i].en_ofs);
> > +
> > +               if (ret)
> > +                       return ret;
> 
> Should you undo the rest of the operations and clear bus protection on
> the ones that were already enabled?
> 

Actually we assume all bus protection operations need to be done
successfully, undo might not be a very useful error handling here. But
I'll consider it carefully.

> > +       }
> > +
> > +       return 0;
> > +}
> > +
> > +int mtk_scpsys_ext_clear_bus_protection(const struct bus_prot *bp_table,
> > +       struct regmap *infracfg, struct regmap *smi_common)
> > +{
> > +       int i;
> > +
> > +       for (i = MAX_STEPS - 1; i >= 0; i--) {
> 
> So when you set protection, you stop at the first bp_table[i].mask ==
> 0, but when you clear it, you call clear_bus_protection for those, as
> well. You should just skip over the ones when bp_table[i].mask == 0?
> 
> e.g.
> if (!bp_table[i].mask)
>    continue;
> 

I'll use the idea of INVALID_TYPE = 0 to fix.

> > +               struct regmap *map;
> > +               int ret;
> > +
> > +               if (bp_table[i].type == IFR_TYPE)
> > +                       map = infracfg;
> > +               else if (bp_table[i].type == SMI_TYPE)
> > +                       map = smi_common;
> > +               else
> > +                       return -EINVAL;
> > +
> > +               ret = clear_bus_protection(map,
> > +                               bp_table[i].mask, bp_table[i].clr_ack_mask,
> > +                               bp_table[i].clr_ofs, bp_table[i].sta_ofs,
> > +                               bp_table[i].en_ofs);
> > +
> > +               if (ret)
> > +                       return ret;
> 
> Similar question, is it ok to just abort? Or should you try to clear
> the protection on all others, too?
> 
> > +       }
> > +
> > +       return 0;
> > +}
> > diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
> > index c6360de4e41e..181bf7bce591 100644
> > --- a/drivers/soc/mediatek/mtk-scpsys.c
> > +++ b/drivers/soc/mediatek/mtk-scpsys.c
> > @@ -12,6 +12,7 @@
> >  #include <linux/pm_domain.h>
> >  #include <linux/regulator/consumer.h>
> >  #include <linux/soc/mediatek/infracfg.h>
> > +#include <linux/soc/mediatek/scpsys-ext.h>
> >
> >  #include <dt-bindings/power/mt2701-power.h>
> >  #include <dt-bindings/power/mt2712-power.h>
> > @@ -121,6 +122,7 @@ static const char * const clk_names[] = {
> >   * @basic_clk_name: provide the same purpose with field "clk_id"
> >   *                  by declaring basic clock prefix name rather than clk_id.
> >   * @caps: The flag for active wake-up action.
> > + * @bp_table: The mask table for multiple step bus protection.
> >   */
> >  struct scp_domain_data {
> >         const char *name;
> > @@ -132,6 +134,7 @@ struct scp_domain_data {
> >         enum clk_id clk_id[MAX_CLKS];
> >         const char *basic_clk_name[MAX_CLKS];
> >         u8 caps;
> > +       struct bus_prot bp_table[MAX_STEPS];
> >  };
> >
> >  struct scp;
> > @@ -155,6 +158,7 @@ struct scp {
> >         struct device *dev;
> >         void __iomem *base;
> >         struct regmap *infracfg;
> > +       struct regmap *smi_common;
> >         struct scp_ctrl_reg ctrl_reg;
> >         bool bus_prot_reg_update;
> >  };
> > @@ -291,6 +295,10 @@ static int scpsys_bus_protect_enable(struct scp_domain *scpd)
> >                 ret = mtk_infracfg_set_bus_protection(scp->infracfg,
> >                                 scpd->data->bus_prot_mask,
> >                                 scp->bus_prot_reg_update);
> > +       } else if (scpd->data->bp_table[0].mask) {
> > +               ret = mtk_scpsys_ext_set_bus_protection(scpd->data->bp_table,
> > +                               scp->infracfg,
> > +                               scp->smi_common);
> >         }
> >
> >         return ret;
> > @@ -305,6 +313,11 @@ static int scpsys_bus_protect_disable(struct scp_domain *scpd)
> >                 ret = mtk_infracfg_clear_bus_protection(scp->infracfg,
> >                                 scpd->data->bus_prot_mask,
> >                                 scp->bus_prot_reg_update);
> > +       } else if (scpd->data->bp_table[0].mask) {
> > +               ret = mtk_scpsys_ext_clear_bus_protection(
> > +                               scpd->data->bp_table,
> > +                               scp->infracfg,
> > +                               scp->smi_common);
> >         }
> >
> >         return ret;
> > @@ -475,6 +488,17 @@ static struct scp *init_scp(struct platform_device *pdev,
> >                 return ERR_CAST(scp->infracfg);
> >         }
> >
> > +       scp->smi_common = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
> > +                       "smi_comm");
> > +
> > +       if (scp->smi_common == ERR_PTR(-ENODEV)) {
> > +               scp->smi_common = NULL;
> > +       } else if (IS_ERR(scp->smi_common)) {
> > +               dev_err(&pdev->dev, "Cannot find smi_common controller: %ld\n",
> > +                               PTR_ERR(scp->smi_common));
> > +               return ERR_CAST(scp->smi_common);
> > +       }
> > +
> >         for (i = 0; i < num; i++) {
> >                 struct scp_domain *scpd = &scp->domains[i];
> >                 const struct scp_domain_data *data = &scp_domain_data[i];
> > diff --git a/include/linux/soc/mediatek/scpsys-ext.h b/include/linux/soc/mediatek/scpsys-ext.h
> > new file mode 100644
> > index 000000000000..d0ed295c88a7
> > --- /dev/null
> > +++ b/include/linux/soc/mediatek/scpsys-ext.h
> > @@ -0,0 +1,39 @@
> > +/* SPDX-License-Identifier: GPL-2.0 */
> > +#ifndef __SOC_MEDIATEK_SCPSYS_EXT_H
> > +#define __SOC_MEDIATEK_SCPSYS_EXT_H
> > +
> > +#define MAX_STEPS      4
> > +
> > +#define BUS_PROT(_type, _set_ofs, _clr_ofs,                    \
> > +               _en_ofs, _sta_ofs, _mask, _clr_ack_mask) {      \
> > +               .type = _type,                                  \
> > +               .set_ofs = _set_ofs,                            \
> > +               .clr_ofs = _clr_ofs,                            \
> > +               .en_ofs = _en_ofs,                              \
> > +               .sta_ofs = _sta_ofs,                            \
> > +               .mask = _mask,                                  \
> > +               .clr_ack_mask = _clr_ack_mask,                  \
> > +       }
> > +
> > +enum regmap_type {
> 
> Maybe add INVALID_TYPE = 0, so that you can skip over those when
> looping over them, instead of checking if mask is 0?
> 

Thanks for advise. I'll use it in next version.

> > +       IFR_TYPE,
> > +       SMI_TYPE,
> > +       MAX_REGMAP_TYPE,
> 
> This is not used, right? Do you really need it?
> 

I'll remove it.

> > +};
> > +
> > +struct bus_prot {
> > +       enum regmap_type type;
> > +       u32 set_ofs;
> > +       u32 clr_ofs;
> > +       u32 en_ofs;
> > +       u32 sta_ofs;
> > +       u32 mask;
> > +       u32 clr_ack_mask;
> > +};
> > +
> > +int mtk_scpsys_ext_set_bus_protection(const struct bus_prot *bp_table,
> > +       struct regmap *infracfg, struct regmap *smi_common);
> > +int mtk_scpsys_ext_clear_bus_protection(const struct bus_prot *bp_table,
> > +       struct regmap *infracfg, struct regmap *smi_common);
> > +
> > +#endif /* __SOC_MEDIATEK_SCPSYS_EXT_H */
> > --
> > 2.18.0
> >

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