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// SPDX-License-Identifier: GPL-2.0-only
/*
* PolarFire SoC (MPFS) Peripheral Clock Reset Controller
*
* Author: Conor Dooley <conor.dooley@microchip.com>
* Copyright (c) 2022 Microchip Technology Inc. and its subsidiaries.
*
*/
#include <linux/auxiliary_bus.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
#include <dt-bindings/clock/microchip,mpfs-clock.h>
#include <soc/microchip/mpfs.h>
/*
* The ENVM reset is the lowest bit in the register & I am using the CLK_FOO
* defines in the dt to make things easier to configure - so this is accounting
* for the offset of 3 there.
*/
#define MPFS_PERIPH_OFFSET CLK_ENVM
#define MPFS_NUM_RESETS 30u
#define MPFS_SLEEP_MIN_US 100
#define MPFS_SLEEP_MAX_US 200
/* block concurrent access to the soft reset register */
static DEFINE_SPINLOCK(mpfs_reset_lock);
/*
* Peripheral clock resets
*/
static int mpfs_assert(struct reset_controller_dev *rcdev, unsigned long id)
{
unsigned long flags;
u32 reg;
spin_lock_irqsave(&mpfs_reset_lock, flags);
reg = mpfs_reset_read(rcdev->dev);
reg |= BIT(id);
mpfs_reset_write(rcdev->dev, reg);
spin_unlock_irqrestore(&mpfs_reset_lock, flags);
return 0;
}
static int mpfs_deassert(struct reset_controller_dev *rcdev, unsigned long id)
{
unsigned long flags;
u32 reg;
spin_lock_irqsave(&mpfs_reset_lock, flags);
reg = mpfs_reset_read(rcdev->dev);
reg &= ~BIT(id);
mpfs_reset_write(rcdev->dev, reg);
spin_unlock_irqrestore(&mpfs_reset_lock, flags);
return 0;
}
static int mpfs_status(struct reset_controller_dev *rcdev, unsigned long id)
{
u32 reg = mpfs_reset_read(rcdev->dev);
/*
* It is safe to return here as MPFS_NUM_RESETS makes sure the sign bit
* is never hit.
*/
return (reg & BIT(id));
}
static int mpfs_reset(struct reset_controller_dev *rcdev, unsigned long id)
{
mpfs_assert(rcdev, id);
usleep_range(MPFS_SLEEP_MIN_US, MPFS_SLEEP_MAX_US);
mpfs_deassert(rcdev, id);
return 0;
}
static const struct reset_control_ops mpfs_reset_ops = {
.reset = mpfs_reset,
.assert = mpfs_assert,
.deassert = mpfs_deassert,
.status = mpfs_status,
};
static int mpfs_reset_xlate(struct reset_controller_dev *rcdev,
const struct of_phandle_args *reset_spec)
{
unsigned int index = reset_spec->args[0];
/*
* CLK_RESERVED does not map to a clock, but it does map to a reset,
* so it has to be accounted for here. It is the reset for the fabric,
* so if this reset gets called - do not reset it.
*/
if (index == CLK_RESERVED) {
dev_err(rcdev->dev, "Resetting the fabric is not supported\n");
return -EINVAL;
}
if (index < MPFS_PERIPH_OFFSET || index >= (MPFS_PERIPH_OFFSET + rcdev->nr_resets)) {
dev_err(rcdev->dev, "Invalid reset index %u\n", index);
return -EINVAL;
}
return index - MPFS_PERIPH_OFFSET;
}
static int mpfs_reset_probe(struct auxiliary_device *adev,
const struct auxiliary_device_id *id)
{
struct device *dev = &adev->dev;
struct reset_controller_dev *rcdev;
rcdev = devm_kzalloc(dev, sizeof(*rcdev), GFP_KERNEL);
if (!rcdev)
return -ENOMEM;
rcdev->dev = dev;
rcdev->dev->parent = dev->parent;
rcdev->ops = &mpfs_reset_ops;
rcdev->of_node = dev->parent->of_node;
rcdev->of_reset_n_cells = 1;
rcdev->of_xlate = mpfs_reset_xlate;
rcdev->nr_resets = MPFS_NUM_RESETS;
return devm_reset_controller_register(dev, rcdev);
}
static const struct auxiliary_device_id mpfs_reset_ids[] = {
{
.name = "clk_mpfs.reset-mpfs",
},
{ }
};
MODULE_DEVICE_TABLE(auxiliary, mpfs_reset_ids);
static struct auxiliary_driver mpfs_reset_driver = {
.probe = mpfs_reset_probe,
.id_table = mpfs_reset_ids,
};
module_auxiliary_driver(mpfs_reset_driver);
MODULE_DESCRIPTION("Microchip PolarFire SoC Reset Driver");
MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
MODULE_IMPORT_NS(MCHP_CLK_MPFS);
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