[PATCH 0/3] ARM: meson: Add reset controller

[PATCH 0/3] ARM: meson: Add reset controller

[Carlo Caione]

Apparently several IPs found in the MesonX SoCs can be reset by programming a
specific bit in a register in the so called AO (Always-On) domain. From the
documentation released by Amlogic under NDA it is not clear which devices can
be reset acting on this register. So far from the sources release by Amlogic it
seems that at least two IPs use this register for reset: RTC and UART. Since I
need it to reset the RTC, I wrote this small driver.

Carlo Caione (3):
  ARM: meson: reset: Add reset controller for MesonX SoCs
  ARM: meson: DTSI: Enable reset controller
  ARM: meson: docs: Add docs for MesonX reset controller

 .../bindings/reset/amlogic,meson6-rst-mgr-ao.txt   |  14 ++
 arch/arm/boot/dts/meson.dtsi                       |   6 +
 drivers/reset/Makefile                             |   1 +
 drivers/reset/reset-meson.c                        | 152 +++++++++++++++++++++
 4 files changed, 173 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/amlogic,meson6-rst-mgr-ao.txt
 create mode 100644 drivers/reset/reset-meson.c

-- 
1.9.1

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[PATCH 1/3] ARM: meson: reset: Add reset controller for MesonX SoCs

[Carlo Caione]

This patch adds support for the reset controller found on the Amlogic
MesonX SoCs. For several devices in the AO (Always-On) power domain, it
is possible to reset them by programming a specific bit in a register.

Signed-off-by: Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
---
 drivers/reset/Makefile      |   1 +
 drivers/reset/reset-meson.c | 152 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 153 insertions(+)
 create mode 100644 drivers/reset/reset-meson.c

diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 60fed3d..74f2372 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -1,4 +1,5 @@
 obj-$(CONFIG_RESET_CONTROLLER) += core.o
 obj-$(CONFIG_ARCH_SOCFPGA) += reset-socfpga.o
 obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
+obj-$(CONFIG_ARCH_MESON) += reset-meson.o
 obj-$(CONFIG_ARCH_STI) += sti/
diff --git a/drivers/reset/reset-meson.c b/drivers/reset/reset-meson.c
new file mode 100644
index 0000000..daeb604
--- /dev/null
+++ b/drivers/reset/reset-meson.c
@@ -0,0 +1,152 @@
+/*
+ * Copyright 2014 Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
+ *
+ * based on
+ * Steffen Trumtrar Reset Controller driver
+ *
+ * Copyright 2014 Steffen Trumtrar
+ *
+ * Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+#define MESON_RST_OFFSET	0x00
+
+struct meson_reset_data {
+	spinlock_t			lock;
+	void __iomem			*membase;
+	struct reset_controller_dev	rcdev;
+};
+
+static int meson_reset_assert(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct meson_reset_data *data = container_of(rcdev,
+						     struct meson_reset_data,
+						     rcdev);
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(&data->lock, flags);
+
+	reg = readl(data->membase + MESON_RST_OFFSET);
+	writel(reg | BIT(id), data->membase + MESON_RST_OFFSET);
+
+	spin_unlock_irqrestore(&data->lock, flags);
+
+	return 0;
+}
+
+static int meson_reset_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct meson_reset_data *data = container_of(rcdev,
+						     struct meson_reset_data,
+						     rcdev);
+
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(&data->lock, flags);
+
+	reg = readl(data->membase + MESON_RST_OFFSET);
+	writel(reg & ~BIT(id), data->membase + MESON_RST_OFFSET);
+
+	spin_unlock_irqrestore(&data->lock, flags);
+
+	return 0;
+}
+
+static int meson_reset_dev(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	int err;
+
+	err = meson_reset_assert(rcdev, id);
+	if (err)
+		return err;
+
+	return meson_reset_deassert(rcdev, id);
+}
+
+static struct reset_control_ops meson_reset_ops = {
+	.assert		= meson_reset_assert,
+	.deassert	= meson_reset_deassert,
+	.reset		= meson_reset_dev,
+};
+
+static int meson_reset_probe(struct platform_device *pdev)
+{
+	struct meson_reset_data *data;
+	struct resource *res;
+
+	/*
+	 * The binding was mainlined without the required property.
+	 * Do not continue, when we encounter an old DT.
+	 */
+	if (!of_find_property(pdev->dev.of_node, "#reset-cells", NULL)) {
+		dev_err(&pdev->dev, "%s missing #reset-cells property\n",
+			pdev->dev.of_node->full_name);
+		return -EINVAL;
+	}
+
+	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	data->membase = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->membase))
+		return PTR_ERR(data->membase);
+
+	spin_lock_init(&data->lock);
+
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.nr_resets = BITS_PER_LONG;
+	data->rcdev.ops = &meson_reset_ops;
+	data->rcdev.of_node = pdev->dev.of_node;
+	reset_controller_register(&data->rcdev);
+
+	return 0;
+}
+
+static int meson_reset_remove(struct platform_device *pdev)
+{
+	struct meson_reset_data *data = platform_get_drvdata(pdev);
+
+	reset_controller_unregister(&data->rcdev);
+
+	return 0;
+}
+
+static const struct of_device_id meson_reset_dt_ids[] = {
+	{ .compatible = "amlogic,meson6-rst-mgr-ao", },
+	{ /* sentinel */ },
+};
+
+static struct platform_driver meson_reset_driver = {
+	.probe	= meson_reset_probe,
+	.remove	= meson_reset_remove,
+	.driver = {
+		.name		= "meson-reset",
+		.owner		= THIS_MODULE,
+		.of_match_table	= meson_reset_dt_ids,
+	},
+};
+module_platform_driver(meson_reset_driver);
+
+MODULE_AUTHOR("Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>");
+MODULE_DESCRIPTION("Meson Reset Controller Driver");
+MODULE_LICENSE("GPL");
-- 
1.9.1

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[PATCH 2/3] ARM: meson: DTSI: Enable reset controller

[Carlo Caione]

Add the node for the reset controller in the DTSI.

Signed-off-by: Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
---
 arch/arm/boot/dts/meson.dtsi | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/arch/arm/boot/dts/meson.dtsi b/arch/arm/boot/dts/meson.dtsi
index e6539ea..1ca864e 100644
--- a/arch/arm/boot/dts/meson.dtsi
+++ b/arch/arm/boot/dts/meson.dtsi
@@ -75,6 +75,12 @@
 			reg = <0xc1109900 0x8>;
 		};
 
+		reset_AO: reset@c8100040 {
+			#reset-cells = <1>;
+			compatible = "amlogic,meson6-rst-mgr-ao";
+			reg = <0xc8100040 0x4>;
+		};
+
 		uart_AO: serial@c81004c0 {
 			compatible = "amlogic,meson-uart";
 			reg = <0xc81004c0 0x14>;
-- 
1.9.1

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[PATCH 3/3] ARM: meson: docs: Add docs for MesonX reset controller

[Carlo Caione]

Signed-off-by: Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
---
 .../bindings/reset/amlogic,meson6-rst-mgr-ao.txt           | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/reset/amlogic,meson6-rst-mgr-ao.txt

diff --git a/Documentation/devicetree/bindings/reset/amlogic,meson6-rst-mgr-ao.txt b/Documentation/devicetree/bindings/reset/amlogic,meson6-rst-mgr-ao.txt
new file mode 100644
index 0000000..4a8fd41
--- /dev/null
+++ b/Documentation/devicetree/bindings/reset/amlogic,meson6-rst-mgr-ao.txt
@@ -0,0 +1,14 @@
+Amlogic MesonX Reset Manager (AO domain)
+
+Required properties:
+- compatible : "amlogic,meson6-rst-mgr-ao"
+- reg : Should contain 1 register ranges(address and length)
+- #reset-cells: 1
+
+Example:
+
+	reset: reset@c8100040 {
+		#reset-cells = <1>;
+		compatible = "amlogic,meson6-rst-mgr-ao";
+		reg = <0xc8100040 0x4>;
+	};
-- 
1.9.1

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Re: [PATCH 1/3] ARM: meson: reset: Add reset controller for MesonX SoCs

[Beniamino Galvani]

On Sun, Oct 12, 2014 at 04:54:37PM +0200, Carlo Caione wrote:
> This patch adds support for the reset controller found on the Amlogic
> MesonX SoCs. For several devices in the AO (Always-On) power domain, it
> is possible to reset them by programming a specific bit in a register.

Hi Carlo,

> [...]
> +
> +static int meson_reset_probe(struct platform_device *pdev)
> +{
> +	struct meson_reset_data *data;
> +	struct resource *res;
> +
> +	/*
> +	 * The binding was mainlined without the required property.
> +	 * Do not continue, when we encounter an old DT.
> +	 */
> +	if (!of_find_property(pdev->dev.of_node, "#reset-cells", NULL)) {
> +		dev_err(&pdev->dev, "%s missing #reset-cells property\n",
> +			pdev->dev.of_node->full_name);
> +		return -EINVAL;
> +	}

Probably the above comment was taken from another driver but is not
relevant here.

> +
> +	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
> +	if (!data)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	data->membase = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(data->membase))
> +		return PTR_ERR(data->membase);
> +
> +	spin_lock_init(&data->lock);
> +
> +	data->rcdev.owner = THIS_MODULE;
> +	data->rcdev.nr_resets = BITS_PER_LONG;
> +	data->rcdev.ops = &meson_reset_ops;
> +	data->rcdev.of_node = pdev->dev.of_node;
> +	reset_controller_register(&data->rcdev);
> +
> +	return 0;
> +}
> +
> +static int meson_reset_remove(struct platform_device *pdev)
> +{
> +	struct meson_reset_data *data = platform_get_drvdata(pdev);

Don't you need to call platform_set_drvdata() in the probe() function
for this to be valid?

> +
> +	reset_controller_unregister(&data->rcdev);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id meson_reset_dt_ids[] = {
> +	{ .compatible = "amlogic,meson6-rst-mgr-ao", },
> +	{ /* sentinel */ },
> +};
> +
> +static struct platform_driver meson_reset_driver = {
> +	.probe	= meson_reset_probe,
> +	.remove	= meson_reset_remove,
> +	.driver = {
> +		.name		= "meson-reset",
> +		.owner		= THIS_MODULE,

I believe you can drop the owner field.

Beniamino
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Re: [PATCH 1/3] ARM: meson: reset: Add reset controller for MesonX SoCs

[Carlo Caione]

On Sun, Oct 12, 2014 at 6:03 PM, Beniamino Galvani <b.galvani-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Hi Carlo,

Hi Beniamino,

>> [...]
>> +
>> +static int meson_reset_probe(struct platform_device *pdev)
>> +{
>> +     struct meson_reset_data *data;
>> +     struct resource *res;
>> +
>> +     /*
>> +      * The binding was mainlined without the required property.
>> +      * Do not continue, when we encounter an old DT.
>> +      */
>> +     if (!of_find_property(pdev->dev.of_node, "#reset-cells", NULL)) {
>> +             dev_err(&pdev->dev, "%s missing #reset-cells property\n",
>> +                     pdev->dev.of_node->full_name);
>> +             return -EINVAL;
>> +     }
>
> Probably the above comment was taken from another driver but is not
> relevant here.

Right. Lazy copy and paste with brain off

>> +
>> +static int meson_reset_remove(struct platform_device *pdev)
>> +{
>> +     struct meson_reset_data *data = platform_get_drvdata(pdev);
>
> Don't you need to call platform_set_drvdata() in the probe() function
> for this to be valid?

Yes. Even though I believe the remove can never happen.

>> +
>> +     reset_controller_unregister(&data->rcdev);
>> +
>> +     return 0;
>> +}
>> +
>> +static const struct of_device_id meson_reset_dt_ids[] = {
>> +     { .compatible = "amlogic,meson6-rst-mgr-ao", },
>> +     { /* sentinel */ },
>> +};
>> +
>> +static struct platform_driver meson_reset_driver = {
>> +     .probe  = meson_reset_probe,
>> +     .remove = meson_reset_remove,
>> +     .driver = {
>> +             .name           = "meson-reset",
>> +             .owner          = THIS_MODULE,
>
> I believe you can drop the owner field.

I will.

Thank you for your review,

-- 
Carlo Caione
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