linux-kernel - [PATCH v3 002/105] reset: simple: Add reset callback

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Message-Id: <be2cecb2654e68385561a15df7967c7723d5531d.1590594512.git-series.maxime@cerno.tech>
Date:   Wed, 27 May 2020 17:47:32 +0200
From:   Maxime Ripard <maxime@...no.tech>
To:     Nicolas Saenz Julienne <nsaenzjulienne@...e.de>,
        Eric Anholt <eric@...olt.net>
Cc:     dri-devel@...ts.freedesktop.org,
        linux-rpi-kernel@...ts.infradead.org,
        bcm-kernel-feedback-list@...adcom.com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Dave Stevenson <dave.stevenson@...pberrypi.com>,
        Tim Gover <tim.gover@...pberrypi.com>,
        Phil Elwell <phil@...pberrypi.com>,
        Maxime Ripard <maxime@...no.tech>,
        Philipp Zabel <p.zabel@...gutronix.de>
Subject: [PATCH v3 002/105] reset: simple: Add reset callback

The reset-simple code lacks a reset callback that is still pretty easy to
implement. The only real thing to consider is the delay needed for a device
to be reset, so let's expose that as part of the reset-simple driver data.

Cc: Philipp Zabel <p.zabel@...gutronix.de>
Reviewed-by: Philipp Zabel <p.zabel@...gutronix.de>
Signed-off-by: Maxime Ripard <maxime@...no.tech>
---
 drivers/reset/reset-simple.c       | 20 ++++++++++++++++++++
 include/linux/reset/reset-simple.h |  7 +++++++
 2 files changed, 27 insertions(+)

diff --git a/drivers/reset/reset-simple.c b/drivers/reset/reset-simple.c
index c854aa351640..e066614818a3 100644
--- a/drivers/reset/reset-simple.c
+++ b/drivers/reset/reset-simple.c
@@ -11,6 +11,7 @@
  * Maxime Ripard <maxime.ripard@...e-electrons.com>
  */
 
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/io.h>
@@ -63,6 +64,24 @@ static int reset_simple_deassert(struct reset_controller_dev *rcdev,
 	return reset_simple_update(rcdev, id, false);
 }
 
+static int reset_simple_reset(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct reset_simple_data *data = to_reset_simple_data(rcdev);
+	int ret;
+
+	if (!data->reset_us)
+		return -ENOTSUPP;
+
+	ret = reset_simple_assert(rcdev, id);
+	if (ret)
+		return ret;
+
+	usleep_range(data->reset_us, data->reset_us * 2);
+
+	return reset_simple_deassert(rcdev, id);
+}
+
 static int reset_simple_status(struct reset_controller_dev *rcdev,
 			       unsigned long id)
 {
@@ -80,6 +99,7 @@ static int reset_simple_status(struct reset_controller_dev *rcdev,
 const struct reset_control_ops reset_simple_ops = {
 	.assert		= reset_simple_assert,
 	.deassert	= reset_simple_deassert,
+	.reset		= reset_simple_reset,
 	.status		= reset_simple_status,
 };
 EXPORT_SYMBOL_GPL(reset_simple_ops);
diff --git a/include/linux/reset/reset-simple.h b/include/linux/reset/reset-simple.h
index 08ccb25a55e6..c3e44f45b0f7 100644
--- a/include/linux/reset/reset-simple.h
+++ b/include/linux/reset/reset-simple.h
@@ -27,6 +27,12 @@
  * @status_active_low: if true, bits read back as cleared while the reset is
  *                     asserted. Otherwise, bits read back as set while the
  *                     reset is asserted.
+ * @reset_us: Minimum delay in microseconds needed that needs to be
+ *            waited for between an assert and a deassert to reset the
+ *            device. If multiple consumers with different delay
+ *            requirements are connected to this controller, it must
+ *            be the largest minimum delay. 0 means that such a delay is
+ *            unknown and the reset operation is unsupported.
  */
 struct reset_simple_data {
 	spinlock_t			lock;
@@ -34,6 +40,7 @@ struct reset_simple_data {
 	struct reset_controller_dev	rcdev;
 	bool				active_low;
 	bool				status_active_low;
+	unsigned int			reset_us;
 };
 
 extern const struct reset_control_ops reset_simple_ops;
-- 
git-series 0.9.1