mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-09-04 18:09:57 +00:00
![Stephen Gallimore](/assets/img/avatar_default.png)
This patch adds a reset controller implementation for STMicroelectronics STi family SoCs; it allows a group of related reset like controls found in multiple system configuration registers to be represented by a single controller device. System configuration registers are accessed through the regmap framework and the mfd/syscon driver. The implementation optionally supports waiting for the reset action to be acknowledged in a separate status register and supports both active high and active low reset lines. These properties are common across all the reset channels in a specific reset controller instance, hence all channels in a paritcular controller are expected to behave in the same way. Signed-off-by: Stephen Gallimore <stephen.gallimore@st.com> Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@st.com> Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
186 lines
4.4 KiB
C
186 lines
4.4 KiB
C
/*
|
|
* Copyright (C) 2013 STMicroelectronics Limited
|
|
* Author: Stephen Gallimore <stephen.gallimore@st.com>
|
|
*
|
|
* Inspired by mach-imx/src.c
|
|
*
|
|
* 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/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 = syscfg_reset_assert(rcdev, idx);
|
|
if (err)
|
|
return err;
|
|
|
|
return syscfg_reset_deassert(rcdev, idx);
|
|
}
|
|
|
|
static struct reset_control_ops syscfg_reset_ops = {
|
|
.reset = syscfg_reset_dev,
|
|
.assert = syscfg_reset_assert,
|
|
.deassert = syscfg_reset_deassert,
|
|
};
|
|
|
|
static int syscfg_reset_controller_register(struct device *dev,
|
|
const struct syscfg_reset_controller_data *data)
|
|
{
|
|
struct syscfg_reset_controller *rc;
|
|
size_t size;
|
|
int i, err;
|
|
|
|
rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
|
|
if (!rc)
|
|
return -ENOMEM;
|
|
|
|
size = sizeof(struct syscfg_reset_channel) * data->nr_channels;
|
|
|
|
rc->channels = devm_kzalloc(dev, size, 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);
|
|
}
|