From: boris.brezillon@free-electrons.com (Boris Brezillon)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH v3 02/14] pwm: Add two helpers to ease relative duty cycle manipulation
Date: Tue, 14 Jun 2016 11:13:10 +0200 [thread overview]
Message-ID: <1465895602-31008-3-git-send-email-boris.brezillon@free-electrons.com> (raw)
In-Reply-To: <1465895602-31008-1-git-send-email-boris.brezillon@free-electrons.com>
The PWM framework expects PWM users to configure the duty cycle in
nanoseconds, but most users just want to express this duty cycle
relatively to the period value (i.e. duty_cycle = 33% of the period).
Add the pwm_{get,set}_relative_duty_cycle() helpers to ease this kind
of conversion.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
---
include/linux/pwm.h | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 56 insertions(+)
diff --git a/include/linux/pwm.h b/include/linux/pwm.h
index a100f6e..05e4ea4 100644
--- a/include/linux/pwm.h
+++ b/include/linux/pwm.h
@@ -181,6 +181,62 @@ static inline void pwm_init_state(const struct pwm_device *pwm,
}
/**
+ * pwm_get_relative_duty_cycle() - Get a relative duty_cycle value
+ * @state: PWM state to extract the duty_cycle from
+ * @scale: target scale of the relative duty cycle
+ *
+ * This functions converts the absolute duty_cycle stored in @state
+ * (expressed in nanosecond) into a value relative to the period.
+ * For example if you want to get the duty_cycle expressed in percent,
+ * call:
+ *
+ * pwm_get_state(pwm, &state);
+ * duty = pwm_get_relative_duty_cycle(&state, 100);
+ */
+static inline unsigned int
+pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
+{
+ if (!state->period)
+ return 0;
+
+ return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
+ state->period);
+}
+
+/**
+ * pwm_set_relative_duty_cycle() - Set a relative duty_cycle value
+ * @state: PWM state to fill
+ * @duty_cycle: relative duty_cycle value
+ * @scale: scale in which @duty_cycle is expressed
+ *
+ * This functions converts a relative duty_cycle into an absolute one
+ * (expressed in nanoseconds), and put the result in state->duty_cycle.
+ *
+ * For example if you want to configure a 50% duty_cycle, call:
+ *
+ * pwm_init_state(pwm, &state);
+ * pwm_set_relative_duty_cycle(&state, 50, 100);
+ * pwm_apply_state(pwm, &state);
+ *
+ * This functions returns -EINVAL if @duty_cycle and/or @scale are
+ * inconsistent (@scale == 0 or @duty_cycle > @scale).
+ */
+static inline int
+pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
+ unsigned int scale)
+{
+ /* Make sure @scale is > 0 and @duty_cycle <= @scale */
+ if (!scale || duty_cycle > scale)
+ return -EINVAL;
+
+ state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
+ state->period,
+ scale);
+
+ return 0;
+}
+
+/**
* struct pwm_ops - PWM controller operations
* @request: optional hook for requesting a PWM
* @free: optional hook for freeing a PWM
--
2.7.4
next prev parent reply other threads:[~2016-06-14 9:13 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 9:13 [PATCH v3 00/14] regulator: pwm: various improvements Boris Brezillon
2016-06-14 9:13 ` [PATCH v3 01/14] pwm: Add an helper to prepare a new PWM state Boris Brezillon
2016-06-14 9:13 ` Boris Brezillon [this message]
2016-06-14 9:13 ` [PATCH v3 03/14] pwm: rockchip: Fix period and duty_cycle approximation Boris Brezillon
2016-06-14 9:13 ` [PATCH v3 04/14] pwm: rockchip: Add support for hardware readout Boris Brezillon
2016-06-14 9:13 ` [PATCH v3 05/14] pwm: rockchip: Avoid glitches on already running PWMs Boris Brezillon
2016-06-14 9:13 ` [PATCH v3 06/14] pwm: rockchip: Add support for atomic update Boris Brezillon
2016-06-14 9:13 ` [PATCH v3 07/14] pwm: sti: Add support for hardware readout Boris Brezillon
2016-06-14 9:13 ` [PATCH v3 08/14] pwm: sti: Avoid glitches on already running PWMs Boris Brezillon
2016-06-14 9:13 ` [PATCH v3 09/14] regulator: pwm: Adjust PWM config at probe time Boris Brezillon
2016-06-14 9:13 ` [PATCH v3 10/14] regulator: pwm: Switch to the atomic PWM API Boris Brezillon
2016-07-05 14:30 ` Mark Brown
2016-06-14 9:13 ` [PATCH v3 11/14] regulator: pwm: Properly initialize the ->state field Boris Brezillon
2016-07-05 14:31 ` Mark Brown
2016-06-14 9:13 ` [PATCH v3 12/14] regulator: pwm: Retrieve correct voltage Boris Brezillon
2016-07-05 14:32 ` Mark Brown
2016-07-08 15:43 ` Thierry Reding
2016-07-09 9:47 ` Mark Brown
2016-07-11 7:02 ` Thierry Reding
2016-07-11 7:20 ` Boris Brezillon
2016-07-11 16:53 ` Doug Anderson
2016-06-14 9:13 ` [PATCH v3 13/14] regulator: pwm: Support extra continuous mode cases Boris Brezillon
2016-07-05 14:34 ` Mark Brown
2016-06-14 9:13 ` [PATCH v3 14/14] regulator: pwm: Document pwm-dutycycle-unit and pwm-dutycycle-range Boris Brezillon
2016-06-16 22:26 ` Rob Herring
2016-07-05 14:36 ` Mark Brown
2016-07-08 16:35 ` [PATCH v3 00/14] regulator: pwm: various improvements Thierry Reding
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