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[RFC PATCH 1/3] reset: Add support for the Amlogic Meson GXBB Reset Controller

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  [RFC PATCH 1/3] reset: Add support for the Amlogic Meson GXBB Reset Controller Neil Armstrong <narmstrong@baylibre.com> - 2016-05-13 16:10 +0200
    Re: [RFC PATCH 1/3] reset: Add support for the Amlogic Meson GXBB Reset Controller Kevin Hilman <khilman@baylibre.com> - 2016-05-14 17:10 +0200
      Re: [RFC PATCH 1/3] reset: Add support for the Amlogic Meson GXBB  Reset Controller Neil Armstrong <narmstrong@baylibre.com> - 2016-05-16 10:50 +0200
    Re: [RFC PATCH 1/3] reset: Add support for the Amlogic Meson GXBB Reset Controller Kevin Hilman <khilman@baylibre.com> - 2016-05-14 19:50 +0200

#1400814 — [RFC PATCH 1/3] reset: Add support for the Amlogic Meson GXBB Reset Controller

This patch adds the platform driver for the Amlogic Meson GXBB Reset
Controller.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
---
 drivers/reset/Kconfig            |   6 ++
 drivers/reset/Makefile           |   1 +
 drivers/reset/reset-meson-gxbb.c | 160 +++++++++++++++++++++++++++++++++++++++
 3 files changed, 167 insertions(+)
 create mode 100644 drivers/reset/reset-meson-gxbb.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index df37212..4ac5c4d 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -12,5 +12,11 @@ menuconfig RESET_CONTROLLER
 
 	  If unsure, say no.
 
+config MESON_GXBB_RESET
+	tristate "Amlogic Meson GXBB Reset Driver"
+	depends on (ARCH_MESON && RESET_CONTROLLER)
+	help
+	  Build the Amlogic Meson GxBB reset driver.
+
 source "drivers/reset/sti/Kconfig"
 source "drivers/reset/hisilicon/Kconfig"
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index a1fc8ed..5ff83a1 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -3,6 +3,7 @@ obj-$(CONFIG_ARCH_LPC18XX) += reset-lpc18xx.o
 obj-$(CONFIG_ARCH_SOCFPGA) += reset-socfpga.o
 obj-$(CONFIG_ARCH_BERLIN) += reset-berlin.o
 obj-$(CONFIG_MACH_PISTACHIO) += reset-pistachio.o
+obj-$(CONFIG_MESON_GXBB_RESET) += reset-meson-gxbb.o
 obj-$(CONFIG_ARCH_SUNXI) += reset-sunxi.o
 obj-$(CONFIG_ARCH_STI) += sti/
 obj-$(CONFIG_ARCH_HISI) += hisilicon/
diff --git a/drivers/reset/reset-meson-gxbb.c b/drivers/reset/reset-meson-gxbb.c
new file mode 100644
index 0000000..798fdf9
--- /dev/null
+++ b/drivers/reset/reset-meson-gxbb.c
@@ -0,0 +1,160 @@
+/*
+ * Copyright (c) 2016 BayLibre, Inc.
+ * Author: Neil Armstrong <narmstrong@baylibre.com>
+ *
+ * This file is dual-licensed: you can use it either under the terms
+ * of the GPL or the X11 license, at your option. Note that this dual
+ * licensing only applies to this file, and not this project as a
+ * whole.
+ *
+ *  a) This library 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.
+ *
+ *     This library is distributed in the hope that it will be useful,
+ *     but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *     GNU General Public License for more details.
+ *
+ * Or, alternatively,
+ *
+ *  b) Permission is hereby granted, free of charge, to any person
+ *     obtaining a copy of this software and associated documentation
+ *     files (the "Software"), to deal in the Software without
+ *     restriction, including without limitation the rights to use,
+ *     copy, modify, merge, publish, distribute, sublicense, and/or
+ *     sell copies of the Software, and to permit persons to whom the
+ *     Software is furnished to do so, subject to the following
+ *     conditions:
+ *
+ *     The above copyright notice and this permission notice shall be
+ *     included in all copies or substantial portions of the Software.
+ *
+ *     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ *     EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ *     OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ *     NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
+ *     HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
+ *     WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ *     FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ *     OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/types.h>
+
+#define REG_COUNT	7
+#define BITS_PER_REG	16
+
+struct meson_gxbb_reset {
+	void *reg_base;
+	struct reset_controller_dev rcdev;
+};
+
+static int meson_gxbb_reset_assert(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	struct meson_gxbb_reset *data =
+		container_of(rcdev, struct meson_gxbb_reset, rcdev);
+	unsigned int bank = id / BITS_PER_REG;
+	unsigned int offset = id % BITS_PER_REG;
+	void *reg_addr = data->reg_base + (bank << 2);
+
+	if (bank >= REG_COUNT)
+		return -EINVAL;
+
+	writel(readl(reg_addr) | BIT(offset), reg_addr);
+
+	return 0;
+}
+
+static int meson_gxbb_reset_deassert(struct reset_controller_dev *rcdev,
+				unsigned long id)
+{
+	struct meson_gxbb_reset *data =
+		container_of(rcdev, struct meson_gxbb_reset, rcdev);
+	unsigned int bank = id / BITS_PER_REG;
+	unsigned int offset = id % BITS_PER_REG;
+	void *reg_addr = data->reg_base + (bank << 2);
+
+	if (bank >= REG_COUNT)
+		return -EINVAL;
+
+	writel(readl(reg_addr) & ~BIT(offset), reg_addr);
+
+	return 0;
+}
+
+static int meson_gxbb_reset_reset(struct reset_controller_dev *rcdev,
+			      unsigned long id)
+{
+	int err;
+
+	err = meson_gxbb_reset_assert(rcdev, id);
+	if (err)
+		return err;
+
+	return meson_gxbb_reset_deassert(rcdev, id);
+}
+
+static const struct reset_control_ops meson_gxbb_reset_ops = {
+	.reset		= meson_gxbb_reset_reset,
+	.assert		= meson_gxbb_reset_assert,
+	.deassert	= meson_gxbb_reset_deassert,
+};
+
+static const struct of_device_id meson_gxbb_reset_dt_ids[] = {
+	 { .compatible = "amlogic,meson-gxbb-reset", },
+	 { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, meson_gxbb_reset_dt_ids);
+
+static int meson_gxbb_reset_probe(struct platform_device *pdev)
+{
+	struct meson_gxbb_reset *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->reg_base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(data->reg_base))
+		return PTR_ERR(data->reg_base);
+
+	platform_set_drvdata(pdev, data);
+
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.nr_resets = REG_COUNT * BITS_PER_REG;
+	data->rcdev.ops = &meson_gxbb_reset_ops;
+	data->rcdev.of_node = pdev->dev.of_node;
+
+	return reset_controller_register(&data->rcdev);
+}
+
+static int meson_gxbb_reset_remove(struct platform_device *pdev)
+{
+	struct meson_gxbb_reset *data = platform_get_drvdata(pdev);
+
+	reset_controller_unregister(&data->rcdev);
+
+	return 0;
+}
+
+static struct platform_driver meson_gxbb_reset_driver = {
+	.probe	= meson_gxbb_reset_probe,
+	.remove	= meson_gxbb_reset_remove,
+	.driver = {
+		.name		= "meson_gxbb_reset",
+		.of_match_table	= meson_gxbb_reset_dt_ids,
+	},
+};
+
+module_platform_driver(meson_gxbb_reset_driver);
-- 
2.7.0

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#1401093

Neil Armstrong <narmstrong@baylibre.com> writes:

> This patch adds the platform driver for the Amlogic Meson GXBB Reset
> Controller.
>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

[...]

> +static int meson_gxbb_reset_assert(struct reset_controller_dev *rcdev,
> +			      unsigned long id)
> +{
> +	struct meson_gxbb_reset *data =
> +		container_of(rcdev, struct meson_gxbb_reset, rcdev);
> +	unsigned int bank = id / BITS_PER_REG;
> +	unsigned int offset = id % BITS_PER_REG;
> +	void *reg_addr = data->reg_base + (bank << 2);
> +
> +	if (bank >= REG_COUNT)
> +		return -EINVAL;
> +
> +	writel(readl(reg_addr) | BIT(offset), reg_addr);

The spec lists these registers as 16-bit registers, so probably readw/writew
are more appropriate here.

> +	return 0;
> +}
> +
> +static int meson_gxbb_reset_deassert(struct reset_controller_dev *rcdev,
> +				unsigned long id)
> +{
> +	struct meson_gxbb_reset *data =
> +		container_of(rcdev, struct meson_gxbb_reset, rcdev);
> +	unsigned int bank = id / BITS_PER_REG;
> +	unsigned int offset = id % BITS_PER_REG;
> +	void *reg_addr = data->reg_base + (bank << 2);
> +
> +	if (bank >= REG_COUNT)
> +		return -EINVAL;
> +
> +	writel(readl(reg_addr) & ~BIT(offset), reg_addr);

and here.

> +	return 0;
> +}

Kevin

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#1401375 — Re: [RFC PATCH 1/3] reset: Add support for the Amlogic Meson GXBB Reset Controller

On 05/14/2016 05:07 PM, Kevin Hilman wrote:
> Neil Armstrong <narmstrong@baylibre.com> writes:
>> +	writel(readl(reg_addr) | BIT(offset), reg_addr);
> 
> The spec lists these registers as 16-bit registers, so probably readw/writew
> are more appropriate here.


Looking at the datasheet, the reset controller is an APB3 module, thus 32bit would be the only data width configured.

Sure, it's strange to only have 16 used bits per registers...

> 
>> +	return 0;
>> +}
>> +
>> +static int meson_gxbb_reset_deassert(struct reset_controller_dev *rcdev,
>> +				unsigned long id)
>> +{
>> +	struct meson_gxbb_reset *data =
>> +		container_of(rcdev, struct meson_gxbb_reset, rcdev);
>> +	unsigned int bank = id / BITS_PER_REG;
>> +	unsigned int offset = id % BITS_PER_REG;
>> +	void *reg_addr = data->reg_base + (bank << 2);
>> +
>> +	if (bank >= REG_COUNT)
>> +		return -EINVAL;
>> +
>> +	writel(readl(reg_addr) & ~BIT(offset), reg_addr);
> 
> and here.
> 
>> +	return 0;
>> +}
> 
> Kevin
> 

Neil

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#1401122

Neil Armstrong <narmstrong@baylibre.com> writes:

> This patch adds the platform driver for the Amlogic Meson GXBB Reset
> Controller.
>
> Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>

[...]

> +struct meson_gxbb_reset {
> +	void *reg_base;

nit: along wit the readw/writel, this should be void __iomem *.

> +	struct reset_controller_dev rcdev;
> +};

Kevin

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