[U-Boot] [PATCH v2 6/8] reset: socfpga: add reset handling for old kernels

[Simon Goldschmidt]

On Thu, Feb 21, 2019 at 11:15 PM Marek Vasut <marex at denx.de> wrote:
>
> On 2/21/19 11:07 PM, Simon Goldschmidt wrote:
> >
> >
> > Am Do., 21. Feb. 2019, 22:56 hat Marek Vasut <marex at denx.de
> > <mailto:marex at denx.de>> geschrieben:
> >
> >     On 2/21/19 10:43 PM, Simon Goldschmidt wrote:
> >     > This adds code to take peripherals out of reset based on an
> >     environment
> >     > variable. This is in preparation for removing the code that does
> >     this from
> >     > SPL.
> >     >
> >     > However, some drivers even in current Linux cannot handle
> >     peripheral reset,
> >     > so until this works, we need a compatibility workaround.
> >     >
> >     > This workaround is implemented in the 'remove' callback of this reset
> >     > driver, which is called on OS_PREPARE: it checks if the environment
> >     > variable "socfpga_permodrst_ungate" - if it is set to 1, it
> >     deasserts all
> >     > peripheral resets, which is what the gen5 SPL did up to now.
> >     >
> >     > This is in preparation to clean up the SPL and implementing proper
> >     reset
> >     > handling for U-Boot.
> >     >
> >     > Signed-off-by: Simon Goldschmidt <simon.k.r.goldschmidt at gmail.com
> >     <mailto:simon.k.r.goldschmidt at gmail.com>>
> >     > ---
> >     >
> >     > Changes in v2:
> >     > - moved from Kernel option "OLD_SOCFPGA_KERNEL_COMPAT" to environment
> >     >   variable "socfpga_permodrst_ungate"
> >     >
> >     >  drivers/reset/reset-socfpga.c | 34 ++++++++++++++++++++++++++++++++++
> >     >  1 file changed, 34 insertions(+)
> >     >
> >     > diff --git a/drivers/reset/reset-socfpga.c
> >     b/drivers/reset/reset-socfpga.c
> >     > index b2acfcd2ec..749f671e05 100644
> >     > --- a/drivers/reset/reset-socfpga.c
> >     > +++ b/drivers/reset/reset-socfpga.c
> >     > @@ -89,6 +89,36 @@ static int socfpga_reset_probe(struct udevice *dev)
> >     >       return 0;
> >     >  }
> >     >
> >     > +#ifndef CONFIG_SPL_BUILD
> >     > +/*
> >     > + * This remove function is called before starting OS to deassert
> >     peripheral
> >     > + * resets for Kernels that don't support this.
> >     > + *
> >     > + * The reset driver checks the environment variable
> >     "socfpga_permodrst_ungate"
> >     > + * when it is removed. If this variable is '1', all peripherals
> >     in 'permodrst'
> >     > + * are taken out of reset before booting into the OS.
> >     > + * This should be required for gen5 systems only that are running
> >     Linux kernels
> >     > + * without proper peripheral reset support for all drivers used.
> >     > + */
> >     > +static int socfpga_reset_remove(struct udevice *dev)
> >     > +{
> >     > +     struct socfpga_reset_data *data = dev_get_priv(dev);
> >     > +     const char *env_str;
> >     > +     long val;
> >     > +
> >     > +     env_str = env_get("socfpga_permodrst_ungate");
> >     > +     if (env_str) {
> >     > +             val = simple_strtol(env_str, NULL, 0);
> >     > +             if (val == 1) {
> >     > +                     puts("Deasserting all peripheral resets\n");
> >     > +                     writel(0, data->membase + 4);
> >     > +             }
> >     > +     }
> >     > +
> >     > +     return 0;
> >     > +}
> >     > +#endif
> >     > +
> >     >  static const struct udevice_id socfpga_reset_match[] = {
> >     >       { .compatible = "altr,rst-mgr" },
> >     >       { /* sentinel */ },
> >     > @@ -101,4 +131,8 @@ U_BOOT_DRIVER(socfpga_reset) = {
> >     >       .probe = socfpga_reset_probe,
> >     >       .priv_auto_alloc_size = sizeof(struct socfpga_reset_data),
> >     >       .ops = &socfpga_reset_ops,
> >     > +#ifndef CONFIG_SPL_BUILD
> >     > +     .remove = socfpga_reset_remove,
> >     > +     .flags  = DM_FLAG_OS_PREPARE,
> >     > +#endif
> >     >  };
> >
> >     Does this work if you use Falcon mode ? :)
> >
> >
> > Probably not, but would anyone be able to use falcon mode in socfpga
> > gen5 given the current SPL size? I think it didn't fit for,a last time I
> > checked.
>
> If you cut it down, why not ?
>
> > And if it fits in the future, we probably don't need this workaraound
> > any more...
> >
> > I did it like that since env_get() broke compilation of SPL. But if you
> > insist of making this work even for SPL, I'll check again.
>
> SPL can also check env, so some more conditionals need to be added.
> Should be a matter of some CONFIG_IS_ENABLED()

OK, I'll try that for V3.

Regards,
Simon