linux-kernel - Re: [PATCH 2/3] drivers/misc: (aspeed-lpc-snoop): Add regmap cleanup on a shutdown.

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Message-ID: <CACPK8XenuLrB-iOCo57FjeoOdEieHyxSM2ZM-X73AfP3fq3r+g@mail.gmail.com>
Date:   Tue, 23 Aug 2022 00:30:30 +0000
From:   Joel Stanley <joel@....id.au>
To:     Igor Kononenko <i.kononenko@...ro.com>
Cc:     Andrew Jeffery <andrew@...id.au>, openbmc@...ts.ozlabs.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-aspeed@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/3] drivers/misc: (aspeed-lpc-snoop): Add regmap cleanup
 on a shutdown.

On Sun, 21 Aug 2022 at 15:54, Igor Kononenko <i.kononenko@...ro.com> wrote:
>
> The bmc might be rebooted while the host is still reachable and the host
> might send requests through configured lpc-kcs channels in same time.
> That leads to raise lpc-snoop interrupts that haven't adjusted IRQ
> handlers on next early kernel boot, because on the aspeed-chip reboot
> might keep registers on a unclean state that is configured on the last
> boot.
>
> The patch brings an way to masking lpc-snoop interrupts all through
> a bmc-rebooting time.
>
> Tested on a YADRO VEGMAN N110 stand.
>
> Signed-off-by: Igor Kononenko <i.kononenko@...ro.com>
> ---
>  drivers/soc/aspeed/aspeed-lpc-snoop.c | 44 +++++++++++++++++++++++++++
>  1 file changed, 44 insertions(+)
>
> diff --git a/drivers/soc/aspeed/aspeed-lpc-snoop.c b/drivers/soc/aspeed/aspeed-lpc-snoop.c
> index eceeaf8dfbeb..6ec47bf1dc6b 100644
> --- a/drivers/soc/aspeed/aspeed-lpc-snoop.c
> +++ b/drivers/soc/aspeed/aspeed-lpc-snoop.c
> @@ -235,6 +235,41 @@ static int aspeed_lpc_enable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
>         return rc;
>  }
>
> +static void aspeed_lpc_reset_regmap(struct aspeed_lpc_snoop *lpc_snoop)
> +{
> +       u8 index;
> +       struct lpc_regman_cleanup {
> +               u32 offset;
> +               u32 mask;
> +               u8 val;
> +       };
> +       static struct lpc_regman_cleanup cleanup_list[] = {
> +               // Prevent handling ENINIT_SNPxW
> +               { .offset = HICR5,
> +                 .mask = HICR5_EN_SNP0W | HICR5_ENINT_SNP0W,
> +                 .val = 0 },
> +               { .offset = HICR5,
> +                 .mask = HICR5_EN_SNP1W | HICR5_ENINT_SNP1W,
> +                 .val = 0 },
> +               { .offset = HICRB,
> +                 .mask = HICRB_ENSNP0D | HICRB_ENSNP1D,
> +                 .val = 0 },
> +               // Reset SNOOP channel IRQ status
> +               { .offset = HICR6,
> +                 .mask = HICR6_STR_SNP0W | HICR6_STR_SNP1W,
> +                 .val = 1 },
> +       };
> +       for (index = 0; index < ARRAY_SIZE(cleanup_list); index++) {

Did you consider open coding the various updates instead of using a
for loop? I don't think the for loop help us here.

You could instead make these three updates:

/* Prevent handling ENINIT_SNPxW */
regmap_clear_bits(lpc_snoop->regmap, HICR5,
                                  HICR5_EN_SNP0W | HICR5_ENINT_SNP0W |
HICR5_EN_SNP1W | HICR5_ENINT_SNP1W);

regmap_clear_bits(lpc_snoop->regmap, HICRB,
                               HICRB_ENSNP0D | HICRB_ENSNP1D);

/* Reset SNOOP channel IRQ status */
regmap_set_bits(lpc_snoop->regmap, HICR6,
                            HICR6_STR_SNP0W | HICR6_STR_SNP1W);



> +               u32 val = 0;
> +
> +               if (cleanup_list[index].val)
> +                       val = cleanup_list[index].mask;
> +               regmap_update_bits(lpc_snoop->regmap,
> +                                  cleanup_list[index].offset,
> +                                  cleanup_list[index].mask, val);
> +       }
> +}
> +
>  static void aspeed_lpc_disable_snoop(struct aspeed_lpc_snoop *lpc_snoop,
>                                      int channel)
>  {
> @@ -285,6 +320,7 @@ static int aspeed_lpc_snoop_probe(struct platform_device *pdev)
>                 return -ENODEV;
>         }
>
> +       aspeed_lpc_reset_regmap(lpc_snoop);
>         dev_set_drvdata(&pdev->dev, lpc_snoop);
>
>         rc = of_property_read_u32_index(dev->of_node, "snoop-ports", 0, &port);
> @@ -345,6 +381,13 @@ static int aspeed_lpc_snoop_remove(struct platform_device *pdev)
>         return 0;
>  }
>
> +static void aspeed_lpc_snoop_shutdown(struct platform_device *pdev)
> +{
> +       struct aspeed_lpc_snoop *lpc_snoop = dev_get_drvdata(&pdev->dev);
> +
> +       aspeed_lpc_reset_regmap(lpc_snoop);
> +}
> +
>  static const struct aspeed_lpc_snoop_model_data ast2400_model_data = {
>         .has_hicrb_ensnp = 0,
>  };
> @@ -370,6 +413,7 @@ static struct platform_driver aspeed_lpc_snoop_driver = {
>         },
>         .probe = aspeed_lpc_snoop_probe,
>         .remove = aspeed_lpc_snoop_remove,
> +       .shutdown = aspeed_lpc_snoop_shutdown,
>  };
>
>  module_platform_driver(aspeed_lpc_snoop_driver);
> --
> 2.25.1
>