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authorAmjad Ouled-Ameur <aouledameur@baylibre.com>2020-11-13 00:00:43 +0100
committerPhilipp Zabel <p.zabel@pengutronix.de>2020-11-16 17:05:28 +0100
commit557acb3d2cd9c82de19f944f6cc967a347735385 (patch)
tree3109b1a54995d97e6ae021da6cba94c0557e03c8 /drivers/reset
parent3650b228f83adda7e5ee532e2b90429c03f7b9ec (diff)
downloadlinux-557acb3d2cd9c82de19f944f6cc967a347735385.tar.bz2
reset: make shared pulsed reset controls re-triggerable
The current reset framework API does not allow to release what is done by reset_control_reset(), IOW decrement triggered_count. Add the new reset_control_rearm() call to do so. When reset_control_reset() has been called once, the counter triggered_count, in the reset framework, is incremented i.e the resource under the reset is in-use and the reset should not be done again. reset_control_rearm() would be the way to state that the resource is no longer used and, that from the caller's perspective, the reset can be fired again if necessary. Signed-off-by: Amjad Ouled-Ameur <aouledameur@baylibre.com> Reported-by: Jerome Brunet <jbrunet@baylibre.com> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Diffstat (limited to 'drivers/reset')
-rw-r--r--drivers/reset/core.c73
1 files changed, 73 insertions, 0 deletions
diff --git a/drivers/reset/core.c b/drivers/reset/core.c
index a2df88e90011..34e89aa0fb5e 100644
--- a/drivers/reset/core.c
+++ b/drivers/reset/core.c
@@ -208,6 +208,39 @@ static int reset_control_array_reset(struct reset_control_array *resets)
return 0;
}
+static int reset_control_array_rearm(struct reset_control_array *resets)
+{
+ struct reset_control *rstc;
+ int i;
+
+ for (i = 0; i < resets->num_rstcs; i++) {
+ rstc = resets->rstc[i];
+
+ if (!rstc)
+ continue;
+
+ if (WARN_ON(IS_ERR(rstc)))
+ return -EINVAL;
+
+ if (rstc->shared) {
+ if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
+ return -EINVAL;
+ } else {
+ if (!rstc->acquired)
+ return -EPERM;
+ }
+ }
+
+ for (i = 0; i < resets->num_rstcs; i++) {
+ rstc = resets->rstc[i];
+
+ if (rstc && rstc->shared)
+ WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);
+ }
+
+ return 0;
+}
+
static int reset_control_array_assert(struct reset_control_array *resets)
{
int ret, i;
@@ -326,6 +359,46 @@ int reset_control_reset(struct reset_control *rstc)
EXPORT_SYMBOL_GPL(reset_control_reset);
/**
+ * reset_control_rearm - allow shared reset line to be re-triggered"
+ * @rstc: reset controller
+ *
+ * On a shared reset line the actual reset pulse is only triggered once for the
+ * lifetime of the reset_control instance, except if this call is used.
+ *
+ * Calls to this function must be balanced with calls to reset_control_reset,
+ * a warning is thrown in case triggered_count ever dips below 0.
+ *
+ * Consumers must not use reset_control_(de)assert on shared reset lines when
+ * reset_control_reset or reset_control_rearm have been used.
+ *
+ * If rstc is NULL the function will just return 0.
+ */
+int reset_control_rearm(struct reset_control *rstc)
+{
+ if (!rstc)
+ return 0;
+
+ if (WARN_ON(IS_ERR(rstc)))
+ return -EINVAL;
+
+ if (reset_control_is_array(rstc))
+ return reset_control_array_rearm(rstc_to_array(rstc));
+
+ if (rstc->shared) {
+ if (WARN_ON(atomic_read(&rstc->deassert_count) != 0))
+ return -EINVAL;
+
+ WARN_ON(atomic_dec_return(&rstc->triggered_count) < 0);
+ } else {
+ if (!rstc->acquired)
+ return -EPERM;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(reset_control_rearm);
+
+/**
* reset_control_assert - asserts the reset line
* @rstc: reset controller
*