From: Guru Das Srinagesh <gurus@codeaurora.org>
To: linux-pwm@vger.kernel.org
Cc: "Guru Das Srinagesh" <gurus@codeaurora.org>,
"Uwe Kleine-König" <uwe@kleine-koenig.org>,
linux-kernel@vger.kernel.org, "Atish Patra" <atish.patra@wdc.com>,
"Yash Shah" <yash.shah@sifive.com>,
"Thierry Reding" <thierry.reding@gmail.com>,
"Palmer Dabbelt" <palmer@dabbelt.com>,
"Paul Walmsley" <paul.walmsley@sifive.com>,
"Subbaraman Narayanamurthy" <subbaram@codeaurora.org>,
linux-riscv@lists.infradead.org
Subject: [PATCH v7 08/13] pwm: sifive: Use 64-bit division macros for period and duty cycle
Date: Mon, 9 Mar 2020 12:35:11 -0700 [thread overview]
Message-ID: <4212f82b8711b2b33f0e71142526d5a7575564e9.1583782035.git.gurus@codeaurora.org> (raw)
In-Reply-To: <cover.1583782035.git.gurus@codeaurora.org>
In-Reply-To: <cover.1583782035.git.gurus@codeaurora.org>
Because period and duty cycle are defined in the PWM framework structs
as ints with units of nanoseconds, the maximum time duration that can be
set is limited to ~2.147 seconds. Redefining them as u64 values will
enable larger time durations to be set.
As a first step, prepare drivers to handle the switch to u64 period and
duty_cycle by replacing division operations involving pwm period and duty cycle
with their 64-bit equivalents as appropriate. The actual switch to u64 period
and duty_cycle follows as a separate patch.
Where the dividend is 64-bit but the divisor is 32-bit, use *_ULL
macros:
- DIV_ROUND_UP_ULL
- DIV_ROUND_CLOSEST_ULL
- div_u64
Where the divisor is 64-bit (dividend may be 32-bit or 64-bit), use
DIV64_* macros:
- DIV64_U64_ROUND_CLOSEST
- div64_u64
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: linux-riscv@lists.infradead.org
Cc: Yash Shah <yash.shah@sifive.com>
Cc: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>
---
drivers/pwm/pwm-sifive.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index cc63f9b..62de0bb 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -181,7 +181,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
* consecutively
*/
num = (u64)duty_cycle * (1U << PWM_SIFIVE_CMPWIDTH);
- frac = DIV_ROUND_CLOSEST_ULL(num, state->period);
+ frac = DIV64_U64_ROUND_CLOSEST(num, state->period);
/* The hardware cannot generate a 100% duty cycle */
frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
--
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project
next parent reply other threads:[~2020-03-09 19:35 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <cover.1583782035.git.gurus@codeaurora.org>
2020-03-09 19:35 ` Guru Das Srinagesh [this message]
2020-03-26 16:37 ` [PATCH v7 08/13] pwm: sifive: Use 64-bit division macros for period and duty cycle Palmer Dabbelt
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