[PATCH v2 0/3] ARM: meson: Add reset controller

[PATCH v2 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.

v2:
* removed useless comment
* added platform_get_drvdata
* removed owner field

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                        | 142 +++++++++++++++++++++
 4 files changed, 163 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 v2 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 | 142 ++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 143 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..59b58e4
--- /dev/null
+++ b/drivers/reset/reset-meson.c
@@ -0,0 +1,142 @@
+/*
+ * 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;
+
+	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);
+
+	platform_set_drvdata(pdev, data);
+
+	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;
+
+	return reset_controller_register(&data->rcdev);
+}
+
+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",
+		.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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Re: [PATCH v2 1/3] ARM: meson: reset: Add reset controller for MesonX SoCs

[Philipp Zabel]

Hi Carlo,

On Tue, Oct 14, 2014 at 08:35:47PM +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.
> 
> Signed-off-by: Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
> ---
>  drivers/reset/Makefile      |   1 +
>  drivers/reset/reset-meson.c | 142 ++++++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 143 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..59b58e4
> --- /dev/null
> +++ b/drivers/reset/reset-meson.c
> @@ -0,0 +1,142 @@
> +/*
> + * Copyright 2014 Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
> + *
> + * based on
> + * Steffen Trumtrar Reset Controller driver

That doesn't sound right. Do you mean socfpga-reset?

> + * Copyright 2014 Steffen Trumtrar
> + *
> + * Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>

Could be combined into a single line.

> + * 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

If there is only one register, I see no need for this.

> +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;
> +
> +	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);
> +
> +	platform_set_drvdata(pdev, data);
> +
> +	data->rcdev.owner = THIS_MODULE;
> +	data->rcdev.nr_resets = BITS_PER_LONG;

Are all bits in this registers reset controls (or rather, are you
positive there is no bit in this register used by anything else)?

> +	data->rcdev.ops = &meson_reset_ops;
> +	data->rcdev.of_node = pdev->dev.of_node;
> +
> +	return reset_controller_register(&data->rcdev);
> +}
> +
> +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",
> +		.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

Other than that, the driver looks good.

regards
Philipp
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Re: [PATCH v2 1/3] ARM: meson: reset: Add reset controller for MesonX SoCs

[Carlo Caione]

On Wed, Oct 15, 2014 at 12:36 AM, Philipp Zabel <pza-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org> wrote:
> Hi Carlo,

Hi Philipp,

>> @@ -0,0 +1,142 @@
>> +/*
>> + * Copyright 2014 Carlo Caione <carlo-KA+7E9HrN00dnm+yROfE0A@public.gmane.org>
>> + *
>> + * based on
>> + * Steffen Trumtrar Reset Controller driver
>
> That doesn't sound right. Do you mean socfpga-reset?

Yes, I'll change it.

>> + * Copyright 2014 Steffen Trumtrar
>> + *
>> + * Steffen Trumtrar <s.trumtrar-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
>
> Could be combined into a single line.

Ok

>> + * 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
>
> If there is only one register, I see no need for this.

Ok

>> +
>> +     data->rcdev.owner = THIS_MODULE;
>> +     data->rcdev.nr_resets = BITS_PER_LONG;
>
> Are all bits in this registers reset controls (or rather, are you
> positive there is no bit in this register used by anything else)?

I'm not sure to be honest. Probably some other bits is used for power
management (I don't have full documentation yet).
I'll submit a v3 with a smaller mask for just the bits I'm going to use.

> Other than that, the driver looks good.

Thank you.

-- 
Carlo Caione
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[PATCH v2 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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Re: [PATCH v2 2/3] ARM: meson: DTSI: Enable reset controller

[Philipp Zabel]

On Tue, Oct 14, 2014 at 08:35:48PM +0200, Carlo Caione wrote:
> 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>;

This needs to go through the same tree as the one meson.dtsi got included in.

regards
Philipp
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[PATCH v2 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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