[U-Boot] [PATCH 3/8] zynq: Add clk framework support to zynq timer

[Stefan.Herbrechtsmeier at weidmueller.com]

> -----Ursprüngliche Nachricht-----
> Von: Michal Simek [mailto:monstr at monstr.eu]
> Gesendet: Dienstag, 10. Januar 2017 15:10
> An: Herbrechtsmeier, Stefan; u-boot at lists.denx.de
> Cc: Albert Aribaud; Herbrechtsmeier, Stefan
> Betreff: Re: [PATCH 3/8] zynq: Add clk framework support to zynq timer
> 
> On 4.1.2017 13:27, stefan.herbrechtsmeier at weidmueller.com wrote:
> > From: Stefan Herbrechtsmeier <stefan.herbrechtsmeier at weidmueller.com>
> >
> > If available use the clock framework to calculate the clock rate of
> > the zynq timer.
> >
> > Signed-off-by: Stefan Herbrechtsmeier
> > <stefan.herbrechtsmeier at weidmueller.com>
> > ---
> >
> >  arch/arm/mach-zynq/timer.c | 25 +++++++++++++++++++++++++
> >  1 file changed, 25 insertions(+)
> >
> > diff --git a/arch/arm/mach-zynq/timer.c b/arch/arm/mach-zynq/timer.c
> > index 8ff82dc..0335cbe 100644
> > --- a/arch/arm/mach-zynq/timer.c
> > +++ b/arch/arm/mach-zynq/timer.c
> > @@ -1,4 +1,7 @@
> >  /*
> > + * Copyright (C) 2017 Weidmüller Interface GmbH & Co. KG
> > + * Stefan Herbrechtsmeier <stefan.herbrechtsmeier at weidmueller.com>
> > + *
> >   * Copyright (C) 2012 Michal Simek <monstr at monstr.eu>
> >   * Copyright (C) 2011-2012 Xilinx, Inc. All rights reserved.
> >   *
> > @@ -25,8 +28,10 @@
> >   * SPDX-License-Identifier:	GPL-2.0+
> >   */
> >
> > +#include <clk.h>
> >  #include <common.h>
> >  #include <div64.h>
> > +#include <dm.h>
> >  #include <asm/io.h>
> >  #include <asm/arch/hardware.h>
> >  #include <asm/arch/clk.h>
> > @@ -56,6 +61,26 @@ int timer_init(void)
> >  			(TIMER_PRESCALE << SCUTIMER_CONTROL_PRESCALER_SHIFT)
> |
> >  			SCUTIMER_CONTROL_ENABLE_MASK;
> >
> > +#if defined(CONFIG_CLK) || defined(CONFIG_SPL_CLK)
> > +	struct udevice *dev;
> > +	struct clk clk;
> > +	int ret;
> > +
> > +	ret = uclass_get_device_by_driver(UCLASS_CLK,
> > +		DM_GET_DRIVER(zynq_clk), &dev);
> > +	if (ret)
> > +		return ret;
> > +
> > +	clk.id = cpu_6or4x_clk;
> 
> This information is already present in DT file. What's the reason not
> to take it from it?
Because this is not a DM driver and I don't know the device node. This could be done if we move the driver to drivers/timer.

> 
> > +	ret = clk_request(dev, &clk);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	gd->cpu_clk = clk_get_rate(&clk);
> > +
> > +	clk_free(&clk);
> 
> Not clk expert but isn't there a way to handle it like it is handled
> for other drivers? clk_get(), clk_get_rate()?
This is the solution I found in other platform drivers. The clk_get function requires a DM device.

> 
> > +#endif
> > +
> >  	gd->arch.timer_rate_hz = (gd->cpu_clk / 2) / (TIMER_PRESCALE +
> 1);
> >
> >  	/* Load the timer counter register */
> >
> 

Regards,
  Stefan



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