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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Copyright (C) 2013 STMicroelectronics Limited
* Author: Stephen Gallimore <stephen.gallimore@st.com>
*
* Inspired by mach-imx/src.c
*/
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/types.h>
#include <linux/of_device.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>
#include "reset-syscfg.h"
/**
* Reset channel regmap configuration
*
* @reset: regmap field for the channel's reset bit.
* @ack: regmap field for the channel's ack bit (optional).
*/
struct syscfg_reset_channel {
struct regmap_field *reset;
struct regmap_field *ack;
};
/**
* A reset controller which groups together a set of related reset bits, which
* may be located in different system configuration registers.
*
* @rst: base reset controller structure.
* @active_low: are the resets in this controller active low, i.e. clearing
* the reset bit puts the hardware into reset.
* @channels: An array of reset channels for this controller.
*/
struct syscfg_reset_controller {
struct reset_controller_dev rst;
bool active_low;
struct syscfg_reset_channel *channels;
};
#define to_syscfg_reset_controller(_rst) \
container_of(_rst, struct syscfg_reset_controller, rst)
static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
unsigned long idx, int assert)
{
struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
const struct syscfg_reset_channel *ch;
u32 ctrl_val = rst->active_low ? !assert : !!assert;
int err;
if (idx >= rcdev->nr_resets)
return -EINVAL;
ch = &rst->channels[idx];
err = regmap_field_write(ch->reset, ctrl_val);
if (err)
return err;
if (ch->ack) {
unsigned long timeout = jiffies + msecs_to_jiffies(1000);
u32 ack_val;
while (true) {
err = regmap_field_read(ch->ack, &ack_val);
if (err)
return err;
if (ack_val == ctrl_val)
break;
if (time_after(jiffies, timeout))
return -ETIME;
cpu_relax();
}
}
return 0;
}
static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
unsigned long idx)
{
return syscfg_reset_program_hw(rcdev, idx, true);
}
static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
unsigned long idx)
{
return syscfg_reset_program_hw(rcdev, idx, false);
}
static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
unsigned long idx)
{
int err;
err = syscfg_reset_assert(rcdev, idx);
if (err)
return err;
return syscfg_reset_deassert(rcdev, idx);
}
static int syscfg_reset_status(struct reset_controller_dev *rcdev,
unsigned long idx)
{
struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
const struct syscfg_reset_channel *ch;
u32 ret_val = 0;
int err;
if (idx >= rcdev->nr_resets)
return -EINVAL;
ch = &rst->channels[idx];
if (ch->ack)
err = regmap_field_read(ch->ack, &ret_val);
else
err = regmap_field_read(ch->reset, &ret_val);
if (err)
return err;
return rst->active_low ? !ret_val : !!ret_val;
}
static const struct reset_control_ops syscfg_reset_ops = {
.reset = syscfg_reset_dev,
.assert = syscfg_reset_assert,
.deassert = syscfg_reset_deassert,
.status = syscfg_reset_status,
};
static int syscfg_reset_controller_register(struct device *dev,
const struct syscfg_reset_controller_data *data)
{
struct syscfg_reset_controller *rc;
int i, err;
rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
if (!rc)
return -ENOMEM;
rc->channels = devm_kcalloc(dev, data->nr_channels,
sizeof(*rc->channels), GFP_KERNEL);
if (!rc->channels)
return -ENOMEM;
rc->rst.ops = &syscfg_reset_ops,
rc->rst.of_node = dev->of_node;
rc->rst.nr_resets = data->nr_channels;
rc->active_low = data->active_low;
for (i = 0; i < data->nr_channels; i++) {
struct regmap *map;
struct regmap_field *f;
const char *compatible = data->channels[i].compatible;
map = syscon_regmap_lookup_by_compatible(compatible);
if (IS_ERR(map))
return PTR_ERR(map);
f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
if (IS_ERR(f))
return PTR_ERR(f);
rc->channels[i].reset = f;
if (!data->wait_for_ack)
continue;
f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
if (IS_ERR(f))
return PTR_ERR(f);
rc->channels[i].ack = f;
}
err = reset_controller_register(&rc->rst);
if (!err)
dev_info(dev, "registered\n");
return err;
}
int syscfg_reset_probe(struct platform_device *pdev)
{
struct device *dev = pdev ? &pdev->dev : NULL;
const struct of_device_id *match;
if (!dev || !dev->driver)
return -ENODEV;
match = of_match_device(dev->driver->of_match_table, dev);
if (!match || !match->data)
return -EINVAL;
return syscfg_reset_controller_register(dev, match->data);
}
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