Re: [PATCH 2/2] crypto: ccree - fix debugfs register access while suspended

[Rafael J. Wysocki]

On Fri, Jan 24, 2020 at 2:30 PM Geert Uytterhoeven
<geert+renesas@xxxxxxxxx> wrote:
>
> Reading the debugfs files under /sys/kernel/debug/ccree/ can be done by
> the user at any time.  On R-Car SoCs, the CCREE device is power-managed
> using a moduile clock, and if this clock is not running, bogus register
> values may be read.
>
> Fix this by filling in the debugfs_regset32.dev field, so debugfs will
> make sure the device is resumed while its registers are being read.
>
> This fixes the bogus values (0x00000260) in the register dumps on R-Car
> H3 ES1.0:
>
>     -e6601000.crypto/regs:HOST_IRR = 0x00000260
>     -e6601000.crypto/regs:HOST_POWER_DOWN_EN = 0x00000260
>     +e6601000.crypto/regs:HOST_IRR = 0x00000038
>     +e6601000.crypto/regs:HOST_POWER_DOWN_EN = 0x00000038
>      e6601000.crypto/regs:AXIM_MON_ERR = 0x00000000
>      e6601000.crypto/regs:DSCRPTR_QUEUE_CONTENT = 0x000002aa
>     -e6601000.crypto/regs:HOST_IMR = 0x00000260
>     +e6601000.crypto/regs:HOST_IMR = 0x017ffeff
>      e6601000.crypto/regs:AXIM_CFG = 0x001f0007
>      e6601000.crypto/regs:AXIM_CACHE_PARAMS = 0x00000000
>     -e6601000.crypto/regs:GPR_HOST = 0x00000260
>     +e6601000.crypto/regs:GPR_HOST = 0x017ffeff
>      e6601000.crypto/regs:AXIM_MON_COMP = 0x00000000
>     -e6601000.crypto/version:SIGNATURE = 0x00000260
>     -e6601000.crypto/version:VERSION = 0x00000260
>     +e6601000.crypto/version:SIGNATURE = 0xdcc63000
>     +e6601000.crypto/version:VERSION = 0xaf400001
>
> Note that this behavior is system-dependent, and the issue does not show
> up on all R-Car Gen3 SoCs and boards.  Even when the device is
> suspended, the module clock may be left enabled, if configured by the
> firmware for Secure Mode, or when controlled by the Real-Time Core.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

LGTM:

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

> ---
>  drivers/crypto/ccree/cc_debugfs.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/crypto/ccree/cc_debugfs.c b/drivers/crypto/ccree/cc_debugfs.c
> index 5669997386988055..35f3a2137502bd96 100644
> --- a/drivers/crypto/ccree/cc_debugfs.c
> +++ b/drivers/crypto/ccree/cc_debugfs.c
> @@ -81,6 +81,7 @@ int cc_debugfs_init(struct cc_drvdata *drvdata)
>         regset->regs = debug_regs;
>         regset->nregs = ARRAY_SIZE(debug_regs);
>         regset->base = drvdata->cc_base;
> +       regset->dev = dev;
>
>         ctx->dir = debugfs_create_dir(drvdata->plat_dev->name, cc_debugfs_dir);
>
> @@ -102,6 +103,7 @@ int cc_debugfs_init(struct cc_drvdata *drvdata)
>                 verset->nregs = ARRAY_SIZE(pid_cid_regs);
>         }
>         verset->base = drvdata->cc_base;
> +       verset->dev = dev;
>
>         debugfs_create_regset32("version", 0400, ctx->dir, verset);
>
> --
> 2.17.1
>