[U-Boot] [PATCH v4 1/9] sunxi: clk: enable clk and reset for CCU devices
Jagan Teki
jagan at amarulasolutions.com
Wed Jan 30 14:19:23 UTC 2019
On Wed, Jan 30, 2019 at 7:13 PM Andre Przywara <andre.przywara at arm.com> wrote:
>
> On Wed, 30 Jan 2019 18:16:44 +0530
> Jagan Teki <jagan at amarulasolutions.com> wrote:
>
> > On Wed, Jan 30, 2019 at 4:26 PM Andre Przywara
> > <andre.przywara at arm.com> wrote:
> > >
> > > On Wed, 30 Jan 2019 16:08:14 +0530
> > > Jagan Teki <jagan at amarulasolutions.com> wrote:
> > >
> > > > On Wed, Jan 30, 2019 at 4:04 PM Andre Przywara
> > > > <andre.przywara at arm.com> wrote:
> > > > >
> > > > > On Tue, 29 Jan 2019 23:56:44 +0530
> > > > > Jagan Teki <jagan at amarulasolutions.com> wrote:
> > > > >
> > > > > Hi,
> > > > >
> > > > > > On Tue, Jan 29, 2019 at 11:47 PM Andre Przywara
> > > > > > <andre.przywara at foss.arm.com> wrote:
> > > > > > >
> > > > > > > On Tue, 29 Jan 2019 23:40:26 +0530
> > > > > > > Jagan Teki <jagan at amarulasolutions.com> wrote:
> > > > > > >
> > > > > > > > On Tue, Jan 29, 2019 at 9:25 PM Andre Przywara
> > > > > > > > <andre.przywara at arm.com> wrote:
> > > > > > > > >
> > > > > > > > > Some Allwinner clock devices have parent clocks and
> > > > > > > > > reset gates itself, which need to be activated for them
> > > > > > > > > to work.
> > > > > > > > >
> > > > > > > > > Add some code to just assert all resets and enable all
> > > > > > > > > clocks given. This should enable the A80 MMC config
> > > > > > > > > clock, which requires both to be activated. The full
> > > > > > > > > CCU devices typically don't require resets, and have
> > > > > > > > > just fixed clocks as their parents. Since we treat both
> > > > > > > > > as optional and enabling fixed clocks is a NOP, this
> > > > > > > > > works for all cases, without the need to differentiate
> > > > > > > > > between those clock types.
> > > > > > > > >
> > > > > > > > > Signed-off-by: Andre Przywara <andre.przywara at arm.com>
> > > > > > > > > ---
> > > > > > > > > drivers/clk/sunxi/clk_sunxi.c | 12 ++++++++++++
> > > > > > > > > 1 file changed, 12 insertions(+)
> > > > > > > > >
> > > > > > > > > diff --git a/drivers/clk/sunxi/clk_sunxi.c
> > > > > > > > > b/drivers/clk/sunxi/clk_sunxi.c index
> > > > > > > > > 62ce2994e4..6d4aeb5315 100644 ---
> > > > > > > > > a/drivers/clk/sunxi/clk_sunxi.c +++
> > > > > > > > > b/drivers/clk/sunxi/clk_sunxi.c @@ -8,6 +8,7 @@
> > > > > > > > > #include <clk-uclass.h>
> > > > > > > > > #include <dm.h>
> > > > > > > > > #include <errno.h>
> > > > > > > > > +#include <reset.h>
> > > > > > > > > #include <asm/io.h>
> > > > > > > > > #include <asm/arch/ccu.h>
> > > > > > > > > #include <linux/log2.h>
> > > > > > > > > @@ -61,6 +62,9 @@ struct clk_ops sunxi_clk_ops = {
> > > > > > > > > int sunxi_clk_probe(struct udevice *dev)
> > > > > > > > > {
> > > > > > > > > struct ccu_priv *priv = dev_get_priv(dev);
> > > > > > > > > + struct clk_bulk clk_bulk;
> > > > > > > > > + struct reset_ctl_bulk rst_bulk;
> > > > > > > > > + int ret;
> > > > > > > > >
> > > > > > > > > priv->base = dev_read_addr_ptr(dev);
> > > > > > > > > if (!priv->base)
> > > > > > > > > @@ -70,5 +74,13 @@ int sunxi_clk_probe(struct udevice
> > > > > > > > > *dev) if (!priv->desc)
> > > > > > > > > return -EINVAL;
> > > > > > > > >
> > > > > > > > > + ret = clk_get_bulk(dev, &clk_bulk);
> > > > > > > > > + if (!ret)
> > > > > > > > > + clk_enable_bulk(&clk_bulk);
> > > > > > > > > +
> > > > > > > > > + ret = reset_get_bulk(dev, &rst_bulk);
> > > > > > > > > + if (!ret)
> > > > > > > > > + reset_deassert_bulk(&rst_bulk);
> > > > > > > > > +
> > > > > > > >
> > > > > > > > Can't we do this locally to clk_a80 probe?
> > > > > > >
> > > > > > > That's the point: there is no such thing. For all SoCs we
> > > > > > > use the shared sunxi_clk_probe() function. Doing this only
> > > > > > > for the A80 would mean to split this up, which is
> > > > > > > duplicating a lot of code for very little effect. The code
> > > > > > > here just enables every clock and reset given, which is
> > > > > > > generic and should always be the right thing.
> > > > > >
> > > > > > But enable and dessert of clock and reset is job respective IP
> > > > > > driver isn't it?
> > > > >
> > > > > Which IP driver are you thinking about? This is "the IP driver"
> > > > > for those clock, isn't it?
> > > >
> > > > IP can be any peripheral like USB, MMC, UART and it those drivers
> > > > job to get and enable the clock isn't it?
> > >
> > > Yes, using the DM_CLK framework. This is what we do: the A80 MMC DT
> > > node refers to the MMC config clock (instead of the generic CCU),
> > > and the MMC driver doesn't care about any requirement this clock has
> > > *itself*.
> > > This is the responsibility of the *A80 MMC config clock driver*,
> > > which we introduce in patch 3/9. So in *this* driver's probe
> > > function you would need to enable the parent clocks, which is
> > > exactly what we do. Just by re-using the existing sunxi_clk_probe()
> > > function.
> > > > I assume this code would do the same thing what these peripheral
> > > > driver do?
> > >
> > > It does, it's just one layer in between.
> > > -----------------------
> > > A64 MMC driver A64 CCU driver fixed clock driver
> > > sunxi_clk_probe()
> > > clk_enable() -> (NULL)
> >
> > Ahh.. It didn't effect other clk drivers except A80?
>
> It affects every CCU device, but most (all?) of them just don't
> specify any resets in the DT and the only clocks most of them have
> there are fixed clocks.
> And even if they would, enabling clocks and de-asserting resets sounds
> like a reasonable thing to do anyway.
> So the reset_get_bulk() call will fail (which we don't care about), and
> the clk_get_bulk() call will return the two fixed clocks, for which
> enable calls are a NOP.
> So it works.
This certainly not so understand to be part of common probe, instead I
would prefer to be part of a80 [1] as of now till CLK framework become
more mature. Let me know, we can push all these to send PR to Tom.
[1] https://paste.ubuntu.com/p/KRgx8kFQjD/
>
> Cheers,
> Andre.
>
>
> >
> > > clk_enable() -> sunxi_clk_enable()
> > > -----------------------
> > > A80 MMC driver A80 MMC cfg clk driver A80 CCU driver fixed
> > > clk sunxi_clk_probe()
> > > clk_enable() -> (NULL)
> > > sunxi_clk_probe()
> > > clk_enable() -> sunxi_clk_enable()
> > > clk_enable() -> sunxi_clk_enable()
> > > -----------------------
> >
> > So these bulk enable /deasserts in sunxi_clk_probe will call
> > respective ops for A80 only and for other the behavior is as before.
> > it it?
>
--
Jagan Teki
Senior Linux Kernel Engineer | Amarula Solutions
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.
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