blob: 483824f2e26915b16c515e688d5f0b7cb4d6dfd6 [file] [log] [blame]
/*
* Simple Reset Controller Driver
*
* Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de>
*
* Based on Allwinner SoCs Reset Controller driver
*
* Copyright 2013 Maxime Ripard
*
* Maxime Ripard <maxime.ripard@free-electrons.com>
*
* 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/device.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
#include <linux/spinlock.h>
#include "reset-simple.h"
static inline struct reset_simple_data *
to_reset_simple_data(struct reset_controller_dev *rcdev)
{
return container_of(rcdev, struct reset_simple_data, rcdev);
}
static int reset_simple_update(struct reset_controller_dev *rcdev,
unsigned long id, bool assert)
{
struct reset_simple_data *data = to_reset_simple_data(rcdev);
int reg_width = sizeof(u32);
int bank = id / (reg_width * BITS_PER_BYTE);
int offset = id % (reg_width * BITS_PER_BYTE);
unsigned long flags;
u32 reg;
spin_lock_irqsave(&data->lock, flags);
reg = readl(data->membase + (bank * reg_width));
if (assert ^ data->active_low)
reg |= BIT(offset);
else
reg &= ~BIT(offset);
writel(reg, data->membase + (bank * reg_width));
spin_unlock_irqrestore(&data->lock, flags);
return 0;
}
static int reset_simple_assert(struct reset_controller_dev *rcdev,
unsigned long id)
{
return reset_simple_update(rcdev, id, true);
}
static int reset_simple_deassert(struct reset_controller_dev *rcdev,
unsigned long id)
{
return reset_simple_update(rcdev, id, false);
}
static int reset_simple_status(struct reset_controller_dev *rcdev,
unsigned long id)
{
struct reset_simple_data *data = to_reset_simple_data(rcdev);
int reg_width = sizeof(u32);
int bank = id / (reg_width * BITS_PER_BYTE);
int offset = id % (reg_width * BITS_PER_BYTE);
u32 reg;
reg = readl(data->membase + (bank * reg_width));
return !(reg & BIT(offset)) ^ !data->status_active_low;
}
const struct reset_control_ops reset_simple_ops = {
.assert = reset_simple_assert,
.deassert = reset_simple_deassert,
.status = reset_simple_status,
};
EXPORT_SYMBOL_GPL(reset_simple_ops);
/**
* struct reset_simple_devdata - simple reset controller properties
* @reg_offset: offset between base address and first reset register.
* @nr_resets: number of resets. If not set, default to resource size in bits.
* @active_low: if true, bits are cleared to assert the reset. Otherwise, bits
* are set to assert the reset.
* @status_active_low: if true, bits read back as cleared while the reset is
* asserted. Otherwise, bits read back as set while the
* reset is asserted.
*/
struct reset_simple_devdata {
u32 reg_offset;
u32 nr_resets;
bool active_low;
bool status_active_low;
};
static const struct reset_simple_devdata reset_simple_active_low = {
.active_low = true,
.status_active_low = true,
};
static const struct of_device_id reset_simple_dt_ids[] = {
{ .compatible = "st,stm32-rcc", },
{ .compatible = "allwinner,sun6i-a31-clock-reset",
.data = &reset_simple_active_low },
{ .compatible = "zte,zx296718-reset",
.data = &reset_simple_active_low },
{ .compatible = "aspeed,ast2400-lpc-reset" },
{ .compatible = "aspeed,ast2500-lpc-reset" },
{ /* sentinel */ },
};
static int reset_simple_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
const struct reset_simple_devdata *devdata;
struct reset_simple_data *data;
void __iomem *membase;
struct resource *res;
u32 reg_offset = 0;
devdata = of_device_get_match_data(dev);
data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
membase = devm_ioremap_resource(dev, res);
if (IS_ERR(membase))
return PTR_ERR(membase);
spin_lock_init(&data->lock);
data->membase = membase;
data->rcdev.owner = THIS_MODULE;
data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE;
data->rcdev.ops = &reset_simple_ops;
data->rcdev.of_node = dev->of_node;
if (devdata) {
reg_offset = devdata->reg_offset;
if (devdata->nr_resets)
data->rcdev.nr_resets = devdata->nr_resets;
data->active_low = devdata->active_low;
data->status_active_low = devdata->status_active_low;
}
data->membase += reg_offset;
return devm_reset_controller_register(dev, &data->rcdev);
}
static struct platform_driver reset_simple_driver = {
.probe = reset_simple_probe,
.driver = {
.name = "simple-reset",
.of_match_table = reset_simple_dt_ids,
},
};
builtin_platform_driver(reset_simple_driver);