linux-kernel - [v3,3/4] reset-controller: ti: introduce a new reset handler

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Date:   Mon, 17 Aug 2020 10:48:41 +0800
From:   Crystal Guo <crystal.guo@...iatek.com>
To:     <p.zabel@...gutronix.de>, <robh+dt@...nel.org>,
        <matthias.bgg@...il.com>
CC:     <srv_heupstream@...iatek.com>,
        <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <s-anna@...com>, <afd@...com>, <seiya.wang@...iatek.com>,
        <stanley.chu@...iatek.com>, <yingjoe.chen@...iatek.com>,
        <fan.chen@...iatek.com>, <yong.liang@...iatek.com>,
        Crystal Guo <crystal.guo@...iatek.com>
Subject: [v3,3/4] reset-controller: ti: introduce a new reset handler

Introduce ti_syscon_reset() to integrate assert and deassert together.
If some modules need do serialized assert and deassert operations
to reset itself, reset_control_reset can be called for convenience.

Such as reset-qcom-aoss.c, it integrates assert and deassert together
by 'reset' method. MTK Socs also need this method to perform reset.

Signed-off-by: Crystal Guo <crystal.guo@...iatek.com>
---
 drivers/reset/reset-ti-syscon.c | 26 ++++++++++++++++++++++++--
 1 file changed, 24 insertions(+), 2 deletions(-)

diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c
index a2635c21db7f..08289342f9af 100644
--- a/drivers/reset/reset-ti-syscon.c
+++ b/drivers/reset/reset-ti-syscon.c
@@ -15,6 +15,7 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/delay.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -56,6 +57,7 @@ struct ti_syscon_reset_data {
 	struct regmap *regmap;
 	struct ti_syscon_reset_control *controls;
 	unsigned int nr_controls;
+	unsigned int reset_duration_us;
 };
 
 #define to_ti_syscon_reset_data(rcdev)	\
@@ -89,7 +91,7 @@ static int ti_syscon_reset_assert(struct reset_controller_dev *rcdev,
 	mask = BIT(control->assert_bit);
 	value = (control->flags & ASSERT_SET) ? mask : 0x0;
 
-	return regmap_update_bits(data->regmap, control->assert_offset, mask, value);
+	return regmap_write_bits(data->regmap, control->assert_offset, mask, value);
 }
 
 /**
@@ -120,7 +122,7 @@ static int ti_syscon_reset_deassert(struct reset_controller_dev *rcdev,
 	mask = BIT(control->deassert_bit);
 	value = (control->flags & DEASSERT_SET) ? mask : 0x0;
 
-	return regmap_update_bits(data->regmap, control->deassert_offset, mask, value);
+	return regmap_write_bits(data->regmap, control->deassert_offset, mask, value);
 }
 
 /**
@@ -158,9 +160,26 @@ static int ti_syscon_reset_status(struct reset_controller_dev *rcdev,
 		!(control->flags & STATUS_SET);
 }
 
+static int ti_syscon_reset(struct reset_controller_dev *rcdev,
+				  unsigned long id)
+{
+	struct ti_syscon_reset_data *data = to_ti_syscon_reset_data(rcdev);
+	int ret;
+
+	ret = ti_syscon_reset_assert(rcdev, id);
+	if (ret)
+		return ret;
+
+	if (data->reset_duration_us)
+		usleep_range(data->reset_duration_us, data->reset_duration_us * 2);
+
+	return ti_syscon_reset_deassert(rcdev, id);
+}
+
 static const struct reset_control_ops ti_syscon_reset_ops = {
 	.assert		= ti_syscon_reset_assert,
 	.deassert	= ti_syscon_reset_deassert,
+	.reset		= ti_syscon_reset,
 	.status		= ti_syscon_reset_status,
 };
 
@@ -204,6 +223,9 @@ static int ti_syscon_reset_probe(struct platform_device *pdev)
 		controls[i].flags = be32_to_cpup(list++);
 	}
 
+	of_property_read_u32(pdev->dev.of_node,	"reset-duration-us",
+				&data->reset_duration_us);
+
 	data->rcdev.ops = &ti_syscon_reset_ops;
 	data->rcdev.owner = THIS_MODULE;
 	data->rcdev.of_node = np;
-- 
2.18.0