linux-kernel - Re: [PATCH 1/2] clocksource: meson6_timer: use register names from the datasheet

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Date:   Thu, 15 Nov 2018 07:23:17 +0100
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     daniel.lezcano@...aro.org
Cc:     linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, linux-arm-kernel@...ts.infradead.org,
        khilman@...libre.com, carlo@...one.org
Subject: Re: [PATCH 1/2] clocksource: meson6_timer: use register names from
 the datasheet

Hi Daniel,

thanks for your feedback!

On Thu, Nov 15, 2018 at 2:35 AM Daniel Lezcano
<daniel.lezcano@...aro.org> wrote:
>
> On 28/10/2018 13:55, Martin Blumenstingl wrote:
> > This makes the driver use the names from S805 datasheet for the
> > preprocessor #defines. This makes it easier to spot that the driver
> > currently only supports Timer A (as clockevent with interrupt support)
> > and Timer E (as clocksource without interrupts). Timer B, C and D (which
> > are similar to Timer A) are currently not supported by the driver.
> >
> > While here, this also removes the internal "CED_ID" and "CSD_ID" defines
> > which are used to identify the timer. These IDs are not described in the
> > datasheet and thus make it harder to compare the code to what's written
> > in the datasheet.
> >
> > Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
> > ---
> >  drivers/clocksource/meson6_timer.c | 110 ++++++++++++++++++-----------
> >  1 file changed, 68 insertions(+), 42 deletions(-)
> >
> > diff --git a/drivers/clocksource/meson6_timer.c b/drivers/clocksource/meson6_timer.c
> > index 92f20991a937..c622135bee9d 100644
> > --- a/drivers/clocksource/meson6_timer.c
> > +++ b/drivers/clocksource/meson6_timer.c
> > @@ -10,6 +10,8 @@
> >   * warranty of any kind, whether express or implied.
> >   */
> >
> > +#include <linux/bitfield.h>
> > +#include <linux/bitops.h>
> >  #include <linux/clk.h>
> >  #include <linux/clockchips.h>
> >  #include <linux/interrupt.h>
> > @@ -20,80 +22,102 @@
> >  #include <linux/of_address.h>
> >  #include <linux/of_irq.h>
> >
> > -#define CED_ID                       0
> > -#define CSD_ID                       4
> > -
> > -#define TIMER_ISA_MUX                0
> > -#define TIMER_ISA_VAL(t)     (((t) + 1) << 2)
> > -
> > -#define TIMER_INPUT_BIT(t)   (2 * (t))
> > -#define TIMER_ENABLE_BIT(t)  (16 + (t))
> > -#define TIMER_PERIODIC_BIT(t)        (12 + (t))
> > +enum meson6_timera_input_clock {
> > +     MESON_TIMERA_CLOCK_1US = 0x0,
> > +     MESON_TIMERA_CLOCK_10US = 0x1,
> > +     MESON_TIMERA_CLOCK_100US = 0x2,
> > +     MESON_TIMERA_CLOCK_1MS = 0x3,
> > +};
> >
> > -#define TIMER_CED_INPUT_MASK (3UL << TIMER_INPUT_BIT(CED_ID))
> > -#define TIMER_CSD_INPUT_MASK (7UL << TIMER_INPUT_BIT(CSD_ID))
> > +enum meson6_timere_input_clock {
> > +     MESON_TIMERE_CLOCK_SYSTEM_CLOCK = 0x0,
> > +     MESON_TIMERE_CLOCK_1US = 0x1,
> > +     MESON_TIMERE_CLOCK_10US = 0x2,
> > +     MESON_TIMERE_CLOCK_100US = 0x3,
> > +     MESON_TIMERE_CLOCK_1MS = 0x4,
> > +};
>
> It is not required to specify the values. The standard defines the
> default first value is zero, and each enum has the value which is +1 of
> the previous one.
the idea behind this is: these are values from the datasheet so I
wanted to make them easy to find when comparing the datasheet with the
driver.
I will replace the enums with simple #defines if there are no
objections (that also makes it consistent with the other register
values in the driver).


Regards
Martin