1/*
  2 * Copyright (C) 2013 STMicroelectronics Limited
  3 * Author: Stephen Gallimore <stephen.gallimore@st.com>
  4 *
  5 * Inspired by mach-imx/src.c
  6 *
  7 * This program is free software; you can redistribute it and/or modify
  8 * it under the terms of the GNU General Public License as published by
  9 * the Free Software Foundation; either version 2 of the License, or
 10 * (at your option) any later version.
 11 */
 12#include <linux/kernel.h>
 13#include <linux/platform_device.h>
 14#include <linux/module.h>
 15#include <linux/err.h>
 16#include <linux/types.h>
 17#include <linux/of_device.h>
 18#include <linux/regmap.h>
 19#include <linux/mfd/syscon.h>
 20
 21#include "reset-syscfg.h"
 22
 23/**
 24 * Reset channel regmap configuration
 25 *
 26 * @reset: regmap field for the channel's reset bit.
 27 * @ack: regmap field for the channel's ack bit (optional).
 28 */
 29struct syscfg_reset_channel {
 30	struct regmap_field *reset;
 31	struct regmap_field *ack;
 32};
 33
 34/**
 35 * A reset controller which groups together a set of related reset bits, which
 36 * may be located in different system configuration registers.
 37 *
 38 * @rst: base reset controller structure.
 39 * @active_low: are the resets in this controller active low, i.e. clearing
 40 *              the reset bit puts the hardware into reset.
 41 * @channels: An array of reset channels for this controller.
 42 */
 43struct syscfg_reset_controller {
 44	struct reset_controller_dev rst;
 45	bool active_low;
 46	struct syscfg_reset_channel *channels;
 47};
 48
 49#define to_syscfg_reset_controller(_rst) \
 50	container_of(_rst, struct syscfg_reset_controller, rst)
 51
 52static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
 53				   unsigned long idx, int assert)
 54{
 55	struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
 56	const struct syscfg_reset_channel *ch;
 57	u32 ctrl_val = rst->active_low ? !assert : !!assert;
 58	int err;
 59
 60	if (idx >= rcdev->nr_resets)
 61		return -EINVAL;
 62
 63	ch = &rst->channels[idx];
 64
 65	err = regmap_field_write(ch->reset, ctrl_val);
 66	if (err)
 67		return err;
 68
 69	if (ch->ack) {
 70		unsigned long timeout = jiffies + msecs_to_jiffies(1000);
 71		u32 ack_val;
 72
 73		while (true) {
 74			err = regmap_field_read(ch->ack, &ack_val);
 75			if (err)
 76				return err;
 77
 78			if (ack_val == ctrl_val)
 79				break;
 80
 81			if (time_after(jiffies, timeout))
 82				return -ETIME;
 83
 84			cpu_relax();
 85		}
 86	}
 87
 88	return 0;
 89}
 90
 91static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
 92			       unsigned long idx)
 93{
 94	return syscfg_reset_program_hw(rcdev, idx, true);
 95}
 96
 97static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
 98				 unsigned long idx)
 99{
100	return syscfg_reset_program_hw(rcdev, idx, false);
101}
102
103static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
104			    unsigned long idx)
105{
106	int err;
107
108	err = syscfg_reset_assert(rcdev, idx);
109	if (err)
110		return err;
111
112	return syscfg_reset_deassert(rcdev, idx);
113}
114
115static int syscfg_reset_status(struct reset_controller_dev *rcdev,
116			       unsigned long idx)
117{
118	struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
119	const struct syscfg_reset_channel *ch;
120	u32 ret_val = 0;
121	int err;
122
123	if (idx >= rcdev->nr_resets)
124		return -EINVAL;
125
126	ch = &rst->channels[idx];
127	if (ch->ack)
128		err = regmap_field_read(ch->ack, &ret_val);
129	else
130		err = regmap_field_read(ch->reset, &ret_val);
131	if (err)
132		return err;
133
134	return rst->active_low ? !ret_val : !!ret_val;
135}
136
137static const struct reset_control_ops syscfg_reset_ops = {
138	.reset    = syscfg_reset_dev,
139	.assert   = syscfg_reset_assert,
140	.deassert = syscfg_reset_deassert,
141	.status   = syscfg_reset_status,
142};
143
144static int syscfg_reset_controller_register(struct device *dev,
145				const struct syscfg_reset_controller_data *data)
146{
147	struct syscfg_reset_controller *rc;
148	int i, err;
149
150	rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
151	if (!rc)
152		return -ENOMEM;
153
154	rc->channels = devm_kcalloc(dev, data->nr_channels,
155				    sizeof(*rc->channels), GFP_KERNEL);
156	if (!rc->channels)
157		return -ENOMEM;
158
159	rc->rst.ops = &syscfg_reset_ops,
160	rc->rst.of_node = dev->of_node;
161	rc->rst.nr_resets = data->nr_channels;
162	rc->active_low = data->active_low;
163
164	for (i = 0; i < data->nr_channels; i++) {
165		struct regmap *map;
166		struct regmap_field *f;
167		const char *compatible = data->channels[i].compatible;
168
169		map = syscon_regmap_lookup_by_compatible(compatible);
170		if (IS_ERR(map))
171			return PTR_ERR(map);
172
173		f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
174		if (IS_ERR(f))
175			return PTR_ERR(f);
176
177		rc->channels[i].reset = f;
178
179		if (!data->wait_for_ack)
180			continue;
181
182		f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
183		if (IS_ERR(f))
184			return PTR_ERR(f);
185
186		rc->channels[i].ack = f;
187	}
188
189	err = reset_controller_register(&rc->rst);
190	if (!err)
191		dev_info(dev, "registered\n");
192
193	return err;
194}
195
196int syscfg_reset_probe(struct platform_device *pdev)
197{
198	struct device *dev = pdev ? &pdev->dev : NULL;
199	const struct of_device_id *match;
200
201	if (!dev || !dev->driver)
202		return -ENODEV;
203
204	match = of_match_device(dev->driver->of_match_table, dev);
205	if (!match || !match->data)
206		return -EINVAL;
207
208	return syscfg_reset_controller_register(dev, match->data);
209}