linux-kernel - [v6,2/3] reset-controller: ti: introduce a new reset handler

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Date:   Wed, 30 Sep 2020 10:21:58 +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>, <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: [v6,2/3] 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 | 40 ++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/drivers/reset/reset-ti-syscon.c b/drivers/reset/reset-ti-syscon.c
index a2635c21db7f..5d1f8306cd4f 100644
--- a/drivers/reset/reset-ti-syscon.c
+++ b/drivers/reset/reset-ti-syscon.c
@@ -15,15 +15,22 @@
  * GNU General Public License for more details.
  */
 
+#include <linux/delay.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
+#include <linux/of_device.h>
 #include <linux/platform_device.h>
 #include <linux/regmap.h>
 #include <linux/reset-controller.h>
 
 #include <dt-bindings/reset/ti-syscon.h>
 
+struct mediatek_reset_data {
+	unsigned char *reset_bits;
+	unsigned int reset_duration_us;
+};
+
 /**
  * struct ti_syscon_reset_control - reset control structure
  * @assert_offset: reset assert control register offset from syscon base
@@ -56,6 +63,7 @@ struct ti_syscon_reset_data {
 	struct regmap *regmap;
 	struct ti_syscon_reset_control *controls;
 	unsigned int nr_controls;
+	const struct mediatek_reset_data *reset_data;
 };
 
 #define to_ti_syscon_reset_data(rcdev)	\
@@ -158,9 +166,29 @@ 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;
+
+	if (data->reset_data) {
+		ret = ti_syscon_reset_assert(rcdev, id);
+		if (ret)
+			return ret;
+		usleep_range(data->reset_data->reset_duration_us,
+			data->reset_data->reset_duration_us * 2);
+
+		return ti_syscon_reset_deassert(rcdev, id);
+	} else {
+		return -ENOTSUPP;
+	}
+}
+
 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,
 };
 
@@ -182,7 +210,11 @@ static int ti_syscon_reset_probe(struct platform_device *pdev)
 	if (IS_ERR(regmap))
 		return PTR_ERR(regmap);
 
-	list = of_get_property(np, "ti,reset-bits", &size);
+	data->reset_data = of_device_get_match_data(&pdev->dev);
+	if (data->reset_data)
+		list = of_get_property(np, data->reset_data->reset_bits, &size);
+	else
+		list = of_get_property(np, "ti,reset-bits", &size);
 	if (!list || (size / sizeof(*list)) % 7 != 0) {
 		dev_err(dev, "invalid DT reset description\n");
 		return -EINVAL;
@@ -217,8 +249,14 @@ static int ti_syscon_reset_probe(struct platform_device *pdev)
 	return devm_reset_controller_register(dev, &data->rcdev);
 }
 
+static const struct mediatek_reset_data mtk_reset_data = {
+	.reset_bits = "mediatek,reset-bits",
+	.reset_duration_us = 10,
+};
+
 static const struct of_device_id ti_syscon_reset_of_match[] = {
 	{ .compatible = "ti,syscon-reset", },
+	{ .compatible = "mediatek,syscon-reset", .data = &mtk_reset_data},
 	{ /* sentinel */ },
 };
 MODULE_DEVICE_TABLE(of, ti_syscon_reset_of_match);
-- 
2.18.0