linux-kernel - [PATCH v3 03/14] pwm: meson: use GENMASK and FIELD

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Message-Id: <20190612195911.4442-4-martin.blumenstingl@googlemail.com>
Date:   Wed, 12 Jun 2019 21:59:00 +0200
From:   Martin Blumenstingl <martin.blumenstingl@...glemail.com>
To:     linux-amlogic@...ts.infradead.org, linux-pwm@...r.kernel.org,
        thierry.reding@...il.com
Cc:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        u.kleine-koenig@...gutronix.de, narmstrong@...libre.com,
        Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Subject: [PATCH v3 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.

Reviewed-by: Neil Armstrong <narmstrong@...libre.com>
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@...glemail.com>
---
 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);
-- 
2.22.0