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/*
* Copyright (c) 2022 Arm Limited. All rights reserved.
*
* This program is free software and is provided to you under the terms of the
* GNU General Public License version 2 as published by the Free Software
* Foundation, and any use by you of this program is subject to the terms
* of such GNU licence.
*
* This program 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, you can access it online at
* http://www.gnu.org/licenses/gpl-2.0.html.
*
* SPDX-License-Identifier: GPL-2.0-only
*/
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
/* External system reset control bits */
#define EXTSYS_CPU_WAIT (0x0)
#define EXTSYS_RST_REQ (0x1)
/* External system reset status bits */
#define EXTSYS_STATUS_NO_RST_REQ (0x0)
#define EXTSYS_STATUS_RST_REQ_NOT_COMPLETED (0x1)
#define EXTSYS_STATUS_RST_REQ_COMPLETED (0x2)
#define EXTSYS_STATUS_MASK(a) (0x3 & ((a) >> 1))
struct cs1k_es_reset_data {
struct reset_controller_dev rcdev;
struct device *dev;
void __iomem *ctrl;
void __iomem *status;
};
int cs1k_es_assert(struct reset_controller_dev *rcdev,
unsigned long id)
{
u32 status;
struct cs1k_es_reset_data *reset =
container_of(rcdev, struct cs1k_es_reset_data, rcdev);
if (id)
return -ENODEV;
dev_dbg(reset->dev, "Asserting reset");
/* set cpu wait and reset request of external system */
writel((1 << EXTSYS_CPU_WAIT) | (1 << EXTSYS_RST_REQ), reset->ctrl);
status = EXTSYS_STATUS_MASK(readl(reset->status));
dev_dbg(reset->dev, "status deasserting reset: %u", status);
return status == EXTSYS_STATUS_RST_REQ_COMPLETED ? 0 : 1;
}
int cs1k_es_deassert(struct reset_controller_dev *rcdev,
unsigned long id)
{
u32 status;
struct cs1k_es_reset_data *reset =
container_of(rcdev, struct cs1k_es_reset_data, rcdev);
if (id)
return -ENODEV;
/* release cpu wait */
dev_dbg(reset->dev, "Deasserting reset");
writel(0, reset->ctrl);
status = EXTSYS_STATUS_MASK(readl(reset->status));
dev_dbg(reset->dev, "status deasserting reset: %u", status);
return status == EXTSYS_STATUS_NO_RST_REQ ? 0 : 1;
}
static struct reset_control_ops cs1k_es_reset_ops = {
.assert = cs1k_es_assert,
.deassert = cs1k_es_deassert,
};
static int of_reset_noop(struct reset_controller_dev *rcdev,
const struct of_phandle_args *reset_spec)
{
return 0;
}
static int cs1k_es_reset_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct cs1k_es_reset_data *data;
struct resource *res;
if (!dev->of_node)
return -ENODEV;
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "rstreg");
data->ctrl = devm_ioremap_resource(dev, res);
if (IS_ERR(data->ctrl))
return PTR_ERR(data->ctrl);
res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "streg");
data->status = devm_ioremap_resource(dev, res);
if (IS_ERR(data->status))
return PTR_ERR(data->status);
data->dev = dev;
platform_set_drvdata(pdev, data);
data->rcdev.owner = THIS_MODULE;
data->rcdev.nr_resets = 1;
data->rcdev.ops = &cs1k_es_reset_ops;
data->rcdev.of_node = pdev->dev.of_node;
/* only one reset line for this reset controller */
data->rcdev.of_xlate = of_reset_noop;
dev_info(dev, "registering reset to core");
return devm_reset_controller_register(dev, &data->rcdev);
}
static int cs1k_es_reset_remove(struct platform_device *pdev)
{
return 0;
}
static const struct of_device_id cs1k_es_reset_match[] = {
{ .compatible = "arm,cs1k_es_rst", .data = 0 },
{ /* sentinel */ },
};
static struct platform_driver cs1k_es_reset_driver = {
.probe = cs1k_es_reset_probe,
.remove = cs1k_es_reset_remove,
.driver = {
.name = "cs1k_es-reset",
.of_match_table = of_match_ptr(cs1k_es_reset_match),
},
};
module_platform_driver(cs1k_es_reset_driver);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Arm Corstone1000 External System Reset Driver");
MODULE_AUTHOR("Arm Ltd");
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