Hi Claudio,
On Di, 2022-04-05 at 14:47 +0000, Claudiu.Beznea@xxxxxxxxxxxxx wrote:
> Hi, Philipp,
>
> On 05.04.2022 14:47, Philipp Zabel wrote:
> > EXTERNAL EMAIL: Do not click links or open attachments unless you
> > know the content is safe
> >
> > Hi Claudiu,
> >
> > On Di, 2022-04-05 at 14:27 +0300, Claudiu Beznea wrote:
> > > SAMA7G5 reset controller has 5 extra lines that goes to different
> > > devices
> > > (3 lines to USB PHYs, 1 line to DDR controller, one line DDR PHY
> > > controller). These reset lines could be requested by different
> > > controller
> > > drivers (e.g. USB PHY driver) and these controllers' drivers
> > > could
> > > assert/deassert these lines when necessary. Thus add support for
> > > reset_controller_dev which brings this functionality.
> > >
> > > Signed-off-by: Claudiu Beznea <claudiu.beznea@xxxxxxxxxxxxx>
> > > ---
> > > drivers/power/reset/at91-reset.c | 92
> > > ++++++++++++++++++++++++++++++--
> > > 1 file changed, 88 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/power/reset/at91-reset.c
> > > b/drivers/power/reset/at91-reset.c
> > > index 0d721e27f545..b04df54c15d2 100644
> > > --- a/drivers/power/reset/at91-reset.c
> > > +++ b/drivers/power/reset/at91-reset.c
> > > @@ -17,6 +17,7 @@
> > > #include <linux/of_address.h>
> > > #include <linux/platform_device.h>
> > > #include <linux/reboot.h>
> > > +#include <linux/reset-controller.h>
> > >
> > > #include <soc/at91/at91sam9_ddrsdr.h>
> > > #include <soc/at91/at91sam9_sdramc.h>
> > > @@ -53,12 +54,16 @@ enum reset_type {
> > > struct at91_reset {
> > > void __iomem *rstc_base;
> > > void __iomem *ramc_base[2];
> > > + void __iomem *dev_base;
> > > + struct reset_controller_dev rcdev;
> > > struct clk *sclk;
> > > struct notifier_block nb;
> > > u32 args;
> > > u32 ramc_lpr;
> > > };
> > >
> > > +#define to_at91_reset(r) container_of(r, struct
> > > at91_reset, rcdev)
> > > +
> > > struct at91_reset_data {
> > > u32 reset_args;
> > > u32 n_device_reset;
> > > @@ -191,6 +196,79 @@ static const struct of_device_id
> > > at91_reset_of_match[] = {
> > > };
> > > MODULE_DEVICE_TABLE(of, at91_reset_of_match);
> > >
> > > +static int at91_reset_update(struct reset_controller_dev *rcdev,
> > > + unsigned long id, bool assert)
> > > +{
> > > + struct at91_reset *reset = to_at91_reset(rcdev);
> > > + u32 val;
> > > +
> > > + val = readl_relaxed(reset->dev_base);
> > > + if (assert)
> > > + val |= BIT(id);
> > > + else
> > > + val &= ~BIT(id);
> > > + writel_relaxed(val, reset->dev_base);
> >
> > This read-modify-update should be protected by a spinlock.
> >
> > > +
> > > + return 0;
> > > +}
> > > +
> > > +static int at91_reset_assert(struct reset_controller_dev *rcdev,
> > > + unsigned long id)
> > > +{
> > > + return at91_reset_update(rcdev, id, true);
> > > +}
> > > +
> > > +static int at91_reset_deassert(struct reset_controller_dev
> > > *rcdev,
> > > + unsigned long id)
> > > +{
> > > + return at91_reset_update(rcdev, id, false);
> > > +}
> > > +
> > > +static int at91_reset_dev_status(struct reset_controller_dev
> > > *rcdev,
> > > + unsigned long id)
> > > +{
> > > + struct at91_reset *reset = to_at91_reset(rcdev);
> > > + u32 val;
> > > +
> > > + val = readl_relaxed(reset->dev_base);
> > > +
> > > + return !!(val & BIT(id));
> > > +}
> > > +
> > > +static const struct reset_control_ops at91_reset_ops = {
> > > + .assert = at91_reset_assert,
> > > + .deassert = at91_reset_deassert,
> > > + .status = at91_reset_dev_status,
> > > +};
> > > +
> > > +static int at91_reset_of_xlate(struct reset_controller_dev
> > > *rcdev,
> > > + const struct of_phandle_args
> > > *reset_spec)
> > > +{
> > > + return reset_spec->args[0];
> > > +}
> >
> > For 1:1 mappings there is no need for a custom of_xlate handler.
> > Just
> > leave of_xlate and of_reset_n_cells empty.
>
> I've double checked that. This would work if reset ids are continuous
> from
> zero to rcdev.nr_resets. This the of_reset_simple_xlate:
>
> static int of_reset_simple_xlate(struct reset_controller_dev *rcdev,
> const struct of_phandle_args
> *reset_spec)
> {
> if (reset_spec->args[0] >= rcdev->nr_resets)
> return -EINVAL;
> return reset_spec->args[0];
> }
>
> But in this driver's case we have 3 ids: 4, 5, 6. That is the reason
> I had this simple xlate function.
I see. In that case I'd say keep the custom of_xlate but let it return
-EINVAL if the args[0] value is not 4, 5, or 6.
Or you could set nr_resets to 7, but unless there are more resets at
the lower bits, that wouldn't necessarily be better.
regards
Philipp
