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

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Date:   Thu, 15 Nov 2018 02:35:56 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>,
        linux-amlogic@...ts.infradead.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de
Cc:     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

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.

Other than that, the changes look ok.



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