From: Nylon Chen <nylon.chen@sifive.com>
To: paul.walmsley@sifive.com, palmer@dabbelt.com,
conor+dt@kernel.org, krzysztof.kozlowski+dt@linaro.org,
robh+dt@kernel.org, u.kleine-koenig@pengutronix.de,
thierry.reding@gmail.com, aou@eecs.berkeley.edu
Cc: zong.li@sifve.com, vincent.chen@sifive.com,
linux-pwm@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org, devicetree@vger.kernel.org,
nylon7717@gmail.com, Nylon Chen <nylon.chen@sifive.com>
Subject: [v6 2/3] pwm: sifive: change the PWM controlled LED algorithm
Date: Tue, 16 Jan 2024 12:10:53 +0800 [thread overview]
Message-ID: <20240116041054.11641-3-nylon.chen@sifive.com> (raw)
In-Reply-To: <20240116041054.11641-1-nylon.chen@sifive.com>
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
next prev parent reply other threads:[~2024-01-16 4:11 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-01-16 4:10 [v6 0/3] Change PWM-controlled LED pin active mode and algorithm Nylon Chen
2024-01-16 4:10 ` [v6 1/3] riscv: dts: sifive: unleashed/unmatched: Remove PWM controlled LED's active-low properties Nylon Chen
2024-01-16 10:20 ` Emil Renner Berthing
2024-01-16 10:44 ` Conor Dooley
2024-01-17 6:37 ` Nylon Chen
2024-01-16 4:10 ` Nylon Chen [this message]
2024-01-16 4:10 ` [v6 3/3] pwm: sifive: Fix the error in the idempotent test within the pwm_apply_state_debug function Nylon Chen
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240116041054.11641-3-nylon.chen@sifive.com \
--to=nylon.chen@sifive.com \
--cc=aou@eecs.berkeley.edu \
--cc=conor+dt@kernel.org \
--cc=devicetree@vger.kernel.org \
--cc=krzysztof.kozlowski+dt@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pwm@vger.kernel.org \
--cc=linux-riscv@lists.infradead.org \
--cc=nylon7717@gmail.com \
--cc=palmer@dabbelt.com \
--cc=paul.walmsley@sifive.com \
--cc=robh+dt@kernel.org \
--cc=thierry.reding@gmail.com \
--cc=u.kleine-koenig@pengutronix.de \
--cc=vincent.chen@sifive.com \
--cc=zong.li@sifve.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).