2019-05-25 18:13:16

by Martin Blumenstingl

Subject: [PATCH 03/14] pwm: meson: use GENMASK and FIELD_PREP for the lo and hi values

meson_pwm_calc() ensures that "lo" is always less than 16 bits wide
(otherwise it would overflow into the "hi" part of the REG_PWM_{A,B}
register).
Use GENMASK and FIELD_PREP for the lo and hi values to make it easier to
spot how wide these are internally. Additionally this is a preparation
step for the .get_state() implementation where the GENMASK() for lo and
hi becomes handy because it can be used with FIELD_GET() to extract the
values from the register REG_PWM_{A,B} register.

No functional changes intended.

Signed-off-by: Martin Blumenstingl <[email protected]>
---
drivers/pwm/pwm-meson.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
index 35b38c7201c3..c62a3ac924d0 100644
--- a/drivers/pwm/pwm-meson.c
+++ b/drivers/pwm/pwm-meson.c
@@ -5,6 +5,8 @@
* Copyright (C) 2014 Amlogic, Inc.
*/

+#include <linux/bitfield.h>
+#include <linux/bits.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/err.h>
@@ -20,7 +22,8 @@

#define REG_PWM_A 0x0
#define REG_PWM_B 0x4
-#define PWM_HIGH_SHIFT 16
+#define PWM_LOW_MASK GENMASK(15, 0)
+#define PWM_HIGH_MASK GENMASK(31, 16)

#define REG_MISC_AB 0x8
#define MISC_B_CLK_EN BIT(23)
@@ -217,7 +220,8 @@ static void meson_pwm_enable(struct meson_pwm *meson, struct pwm_device *pwm)
value |= clk_enable;
writel(value, meson->base + REG_MISC_AB);

- value = (channel->hi << PWM_HIGH_SHIFT) | channel->lo;
+ value = FIELD_PREP(PWM_HIGH_MASK, channel->hi) |
+ FIELD_PREP(PWM_LOW_MASK, channel->lo);
writel(value, meson->base + offset);

value = readl(meson->base + REG_MISC_AB);
--
2.21.0

2019-05-27 12:28:10

by Neil Armstrong

Subject: Re: [PATCH 03/14] pwm: meson: use GENMASK and FIELD_PREP for the lo and hi values

On 25/05/2019 20:11, Martin Blumenstingl wrote:
> meson_pwm_calc() ensures that "lo" is always less than 16 bits wide
> (otherwise it would overflow into the "hi" part of the REG_PWM_{A,B}
> register).
> Use GENMASK and FIELD_PREP for the lo and hi values to make it easier to
> spot how wide these are internally. Additionally this is a preparation
> step for the .get_state() implementation where the GENMASK() for lo and
> hi becomes handy because it can be used with FIELD_GET() to extract the
> values from the register REG_PWM_{A,B} register.
>
> No functional changes intended.
>
> Signed-off-by: Martin Blumenstingl <[email protected]>
> ---
> drivers/pwm/pwm-meson.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pwm/pwm-meson.c b/drivers/pwm/pwm-meson.c
> index 35b38c7201c3..c62a3ac924d0 100644
> --- a/drivers/pwm/pwm-meson.c
> +++ b/drivers/pwm/pwm-meson.c
> @@ -5,6 +5,8 @@
> * Copyright (C) 2014 Amlogic, Inc.
> */
>
> +#include <linux/bitfield.h>
> +#include <linux/bits.h>
> #include <linux/clk.h>
> #include <linux/clk-provider.h>
> #include <linux/err.h>
> @@ -20,7 +22,8 @@
>
> #define REG_PWM_A 0x0
> #define REG_PWM_B 0x4
> -#define PWM_HIGH_SHIFT 16
> +#define PWM_LOW_MASK GENMASK(15, 0)
> +#define PWM_HIGH_MASK GENMASK(31, 16)
>
> #define REG_MISC_AB 0x8
> #define MISC_B_CLK_EN BIT(23)
> @@ -217,7 +220,8 @@ static void meson_pwm_enable(struct meson_pwm *meson, struct pwm_device *pwm)
> value |= clk_enable;
> writel(value, meson->base + REG_MISC_AB);
>
> - value = (channel->hi << PWM_HIGH_SHIFT) | channel->lo;
> + value = FIELD_PREP(PWM_HIGH_MASK, channel->hi) |
> + FIELD_PREP(PWM_LOW_MASK, channel->lo);
> writel(value, meson->base + offset);
>
> value = readl(meson->base + REG_MISC_AB);
>

Reviewed-by: Neil Armstrong <[email protected]>