Received-SPF: pass (google.com: domain of linux-kernel+bounces-34764-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
From: Nylon Chen <nylon.chen@sifive.com>
To: linux-riscv@lists.infradead.org,
	devicetree@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	linux-pwm@vger.kernel.org,
	conor@kernel.org,
	robh+dt@kernel.org,
	krzysztof.kozlowski+dt@linaro.org,
	palmer@dabbelt.com,
	paul.walmsley@sifive.com,
	aou@eecs.berkeley.edu,
	thierry.reding@gmail.com,
	u.kleine-koenig@pengutronix.de
Cc: vincent.chen@sifive.com,
	zong.li@sifve.com,
	nylon.chen@sifive.com,
	nylon7717@gmail.com
Subject: [PATCH v7 2/3] pwm: sifive: change the PWM controlled LED algorithm
Date: Tue, 23 Jan 2024 14:17:47 +0800
Message-ID: <20240123061748.8844-3-nylon.chen@sifive.com>
In-Reply-To: <20240123061748.8844-1-nylon.chen@sifive.com>
References: <20240123061748.8844-1-nylon.chen@sifive.com>
Precedence: bulk
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit

The `frac` variable represents the pulse inactive time, and the result
of this algorithm is the pulse active time. Therefore, we must reverse the result.

The reference is SiFive FU740-C000 Manual[0]

Link: https://sifive.cdn.prismic.io/sifive/1a82e600-1f93-4f41-b2d8-86ed8b16acba_fu740-c000-manual-v1p6.pdf [0]

Co-developed-by: Zong Li <zong.li@sifve.com>
Signed-off-by: Zong Li <zong.li@sifve.com>
Co-developed-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Vincent Chen <vincent.chen@sifive.com>
Signed-off-by: Nylon Chen <nylon.chen@sifive.com>
---
 drivers/pwm/pwm-sifive.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/pwm/pwm-sifive.c b/drivers/pwm/pwm-sifive.c
index eabddb7c7820..b07c8598bb21 100644
--- a/drivers/pwm/pwm-sifive.c
+++ b/drivers/pwm/pwm-sifive.c
@@ -113,6 +113,7 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	u32 duty, val;
 
 	duty = readl(ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
+	duty = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - duty;
 
 	state->enabled = duty > 0;
 
@@ -123,11 +124,10 @@ static int pwm_sifive_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
 	state->period = ddata->real_period;
 	state->duty_cycle =
 		(u64)duty * ddata->real_period >> PWM_SIFIVE_CMPWIDTH;
-	state->polarity = PWM_POLARITY_INVERSED;
+	state->polarity = PWM_POLARITY_NORMAL;
 
 	return 0;
 }
-
 static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 			    const struct pwm_state *state)
 {
@@ -139,7 +139,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	int ret = 0;
 	u32 frac;
 
-	if (state->polarity != PWM_POLARITY_INVERSED)
+	if (state->polarity != PWM_POLARITY_NORMAL)
 		return -EINVAL;
 
 	cur_state = pwm->state;
@@ -159,6 +159,7 @@ static int pwm_sifive_apply(struct pwm_chip *chip, struct pwm_device *pwm,
 	frac = DIV64_U64_ROUND_CLOSEST(num, state->period);
 	/* The hardware cannot generate a 100% duty cycle */
 	frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
+	frac = (1U << PWM_SIFIVE_CMPWIDTH) - 1 - frac;
 
 	mutex_lock(&ddata->lock);
 	if (state->period != ddata->approx_period) {
-- 
2.42.0