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

[Simon Goldschmidt]

Am Do., 21. Feb. 2019, 22:56 hat Marek Vasut <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>
> > ---
> >
> > 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.

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.

Regards,
Simon

>