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From:   Guru Das Srinagesh <gurus@codeaurora.org>
To:     linux-pwm@vger.kernel.org
Cc:     Thierry Reding <thierry.reding@gmail.com>,
        =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= <uwe@kleine-koenig.org>,
        Subbaraman Narayanamurthy <subbaram@codeaurora.org>,
        linux-kernel@vger.kernel.org,
        Guru Das Srinagesh <gurus@codeaurora.org>,
        Shawn Guo <shawnguo@kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Pengutronix Kernel Team <kernel@pengutronix.de>,
        Fabio Estevam <festevam@gmail.com>,
        NXP Linux Team <linux-imx@nxp.com>
Subject: [PATCH v7 07/13] pwm: imx27: Use 64-bit division macros for period and duty cycle
Date:   Mon,  9 Mar 2020 12:35:10 -0700
Message-Id: <cc36c14cffe64d12897d4e7ad0de4c85ae9fbef0.1583782035.git.gurus@codeaurora.org>
In-Reply-To: <cover.1583782035.git.gurus@codeaurora.org>
References: <cover.1583782035.git.gurus@codeaurora.org>
In-Reply-To: <cover.1583782035.git.gurus@codeaurora.org>
References: <cover.1583782035.git.gurus@codeaurora.org>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>

Signed-off-by: Guru Das Srinagesh <gurus@codeaurora.org>
---
 drivers/pwm/pwm-imx27.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-imx27.c b/drivers/pwm/pwm-imx27.c
index 35a7ac42..b7d38d0 100644
--- a/drivers/pwm/pwm-imx27.c
+++ b/drivers/pwm/pwm-imx27.c
@@ -208,7 +208,7 @@ static void pwm_imx27_wait_fifo_slot(struct pwm_chip *chip,
 	sr = readl(imx->mmio_base + MX3_PWMSR);
 	fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr);
 	if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
-		period_ms = DIV_ROUND_UP(pwm_get_period(pwm),
+		period_ms = DIV_ROUND_UP_ULL(pwm_get_period(pwm),
 					 NSEC_PER_MSEC);
 		msleep(period_ms);
 
@@ -240,8 +240,7 @@ static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 
 	period_cycles /= prescale;
 	c = (unsigned long long)period_cycles * state->duty_cycle;
-	do_div(c, state->period);
-	duty_cycles = c;
+	duty_cycles = div64_u64(c, state->period);
 
 	/*
 	 * according to imx pwm RM, the real period value should be PERIOD
-- 
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