Re: [PATCH v9 4/9] soc: mediatek: Add multiple step bus protection control

[Nicolas Boichat]

On Tue, Dec 17, 2019 at 10:51 AM Weiyi Lu <weiyi.lu@xxxxxxxxxxxx> wrote:
>
> On Mon, 2019-12-16 at 15:21 +0800, Nicolas Boichat wrote:
> > On Tue, Dec 10, 2019 at 2:47 PM Weiyi Lu <weiyi.lu@xxxxxxxxxxxx> 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 customized arguments.
> > >
> > > Signed-off-by: Weiyi Lu <weiyi.lu@xxxxxxxxxxxx>
> > > ---
> > >  drivers/soc/mediatek/Makefile           |  2 +-
> > >  drivers/soc/mediatek/mtk-scpsys-ext.c   | 99 +++++++++++++++++++++++++++++++++
> > >  drivers/soc/mediatek/mtk-scpsys.c       | 39 +++++++++----
> > >  include/linux/soc/mediatek/scpsys-ext.h | 39 +++++++++++++
> > >  4 files changed, 168 insertions(+), 11 deletions(-)
> > >  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 b017330..b442be9 100644
> > > --- a/drivers/soc/mediatek/Makefile
> > > +++ b/drivers/soc/mediatek/Makefile
> > > @@ -1,5 +1,5 @@
> > >  # SPDX-License-Identifier: GPL-2.0-only
> > >  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 0000000..4f1adda
> > > --- /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 <Owen.Chen@xxxxxxxxxxxx>
> > > + */
> > > +#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);
> >
> > At least for 8183, we never seen to use the reg_set case, can we
> > simplify this function?
> >
>
> Actually 6765 will use it and all the other MediaTek chips at least in
> near future.
> https://patchwork.kernel.org/patch/11042003/

Ok, that's fine then.

> > > +
> > > +       return regmap_read_poll_timeout(map, reg_sta,
> > > +                       val, (val & ack_mask) == ack_mask,
> > > +                       MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> >
> > From 8183, I see that you have either:
> >  1. mask == ack_mask
> >  2. ack_mask == 0 (essentially this skips this test)
> >
> > Would it be simpler to just skip this test if reg_sta == 0, and always
> > assume mask == ack_mask otherwise?
> >
> > e.g.
> > if (reg_sta == 0)
> >    return 0;
> >
> > return regmap_read_poll_timeout(map, reg_sta,
> >                        val, (val & mask) == mask,
> >                        MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
> >
>
> I'm not sure if you mean ack_mask == 0?
> reg_sta would be possible to be 0 because it's a register address
> offset.

Right, so maybe "0" is not a good invalid value, or maybe you can have a
#define REG_STA_INVALID U32_MAX

And then test for:
if (reg_sta == REG_STA_INVALID)
   return 0;

My point here is that mask and ack_mask are always the same (unless
you don't care about reading back the status), so maybe you only need
to specify mask?

(but if you need different mask and ack_mask for future chips, feel
free to ignore)

> I guess what you'd actually suggest is like below?
>
> if (ack_mask == 0)
>     return 0;
>
> return regmap_read_poll_timeout(map, reg_sta,
>                        val, (val & mask) == mask,
>                        MTK_POLL_DELAY_US, MTK_POLL_TIMEOUT);
>
>
> > > +}
> > > +
> > > [snip]
> > > +
> > > +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; i++) {
> > > +               struct regmap *map = NULL;
> > > +               int ret;
> > > +
> > > +               if (bp_table[i].type == INVALID_TYPE)
> > > +                       continue;
> >
> > break? (but yes the one below in mtk_scpsys_ext_clear_bus_protection
> > has to be continue).
> >
>
> Thanks. I'll fix in next version.
>
> > > +               else if (bp_table[i].type == IFR_TYPE)
> > > +                       map = infracfg;
> > > +               else if (bp_table[i].type == SMI_TYPE)
> > > +                       map = smi_common;
> > > +
> > > +               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;
> > > +       }
> > > +
> > > +       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--) {
> > > +               struct regmap *map = NULL;
> > > +               int ret;
> > > +
> > > +               if (bp_table[i].type == INVALID_TYPE)
> > > +                       continue;
> > > +               else if (bp_table[i].type == IFR_TYPE)
> > > +                       map = infracfg;
> > > +               else if (bp_table[i].type == SMI_TYPE)
> > > +                       map = smi_common;
> > > +
> > > +               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;
> > > +       }
> > > +
> > > +       return 0;
> > > +}
> > > diff --git a/drivers/soc/mediatek/mtk-scpsys.c b/drivers/soc/mediatek/mtk-scpsys.c
> > > index 915d635..466bb749 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>
> > > @@ -120,6 +121,7 @@ enum clk_id {
> > >   * @basic_clk_id: 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;
> > > @@ -131,6 +133,7 @@ struct scp_domain_data {
> > >         enum clk_id clk_id[MAX_CLKS];
> > >         const char *basic_clk_id[MAX_CLKS];
> > >         u8 caps;
> > > +       struct bus_prot bp_table[MAX_STEPS];
> >
> > As with the previous patch, I'm not a big fan of having 2 approaches
> > for something similar (bus_prot_mask vs bp_table), can we define a
> > simple macro for this?
> > e.g.:
> > .bp_table = BUS_PROT_SINGLE(mask)
>
> Agree! I'll fix it.
>
>