From 102a0743326a03cd1a1202ceda21e175b7d3575c Mon Sep 17 00:00:00 2001
From: hc <hc@nodka.com>
Date: Tue, 20 Feb 2024 01:20:52 +0000
Subject: [PATCH] add new system file
---
kernel/drivers/pwm/pwm-sifive.c | 21 ++++++++++++++++-----
1 files changed, 16 insertions(+), 5 deletions(-)
diff --git a/kernel/drivers/pwm/pwm-sifive.c b/kernel/drivers/pwm/pwm-sifive.c
index 9cc0612..52a55ba 100644
--- a/kernel/drivers/pwm/pwm-sifive.c
+++ b/kernel/drivers/pwm/pwm-sifive.c
@@ -41,7 +41,7 @@
struct pwm_sifive_ddata {
struct pwm_chip chip;
- struct mutex lock; /* lock to protect user_count */
+ struct mutex lock; /* lock to protect user_count and approx_period */
struct notifier_block notifier;
struct clk *clk;
void __iomem *regs;
@@ -76,6 +76,7 @@
mutex_unlock(&ddata->lock);
}
+/* Called holding ddata->lock */
static void pwm_sifive_update_clock(struct pwm_sifive_ddata *ddata,
unsigned long rate)
{
@@ -163,7 +164,6 @@
return ret;
}
- mutex_lock(&ddata->lock);
cur_state = pwm->state;
enabled = cur_state.enabled;
@@ -182,14 +182,23 @@
/* The hardware cannot generate a 100% duty cycle */
frac = min(frac, (1U << PWM_SIFIVE_CMPWIDTH) - 1);
+ mutex_lock(&ddata->lock);
if (state->period != ddata->approx_period) {
- if (ddata->user_count != 1) {
+ /*
+ * Don't let a 2nd user change the period underneath the 1st user.
+ * However if ddate->approx_period == 0 this is the first time we set
+ * any period, so let whoever gets here first set the period so other
+ * users who agree on the period won't fail.
+ */
+ if (ddata->user_count != 1 && ddata->approx_period) {
+ mutex_unlock(&ddata->lock);
ret = -EBUSY;
goto exit;
}
ddata->approx_period = state->period;
pwm_sifive_update_clock(ddata, clk_get_rate(ddata->clk));
}
+ mutex_unlock(&ddata->lock);
writel(frac, ddata->regs + PWM_SIFIVE_PWMCMP(pwm->hwpwm));
@@ -198,7 +207,6 @@
exit:
clk_disable(ddata->clk);
- mutex_unlock(&ddata->lock);
return ret;
}
@@ -217,8 +225,11 @@
struct pwm_sifive_ddata *ddata =
container_of(nb, struct pwm_sifive_ddata, notifier);
- if (event == POST_RATE_CHANGE)
+ if (event == POST_RATE_CHANGE) {
+ mutex_lock(&ddata->lock);
pwm_sifive_update_clock(ddata, ndata->new_rate);
+ mutex_unlock(&ddata->lock);
+ }
return NOTIFY_OK;
}
--
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