1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 2016 Maxime Ripard
4 *
5 * Maxime Ripard <maxime.ripard@free-electrons.com>
6 */
7
8#include <linux/clk.h>
9#include <linux/clk-provider.h>
10#include <linux/device.h>
11#include <linux/iopoll.h>
12#include <linux/module.h>
13#include <linux/slab.h>
14
15#include "ccu_common.h"
16#include "ccu_gate.h"
17#include "ccu_reset.h"
18
19struct sunxi_ccu {
20	const struct sunxi_ccu_desc	*desc;
21	spinlock_t			lock;
22	struct ccu_reset		reset;
23};
24
25void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
26{
27	void __iomem *addr;
28	u32 reg;
29
30	if (!lock)
31		return;
32
33	if (common->features & CCU_FEATURE_LOCK_REG)
34		addr = common->base + common->lock_reg;
35	else
36		addr = common->base + common->reg;
37
38	WARN_ON(readl_relaxed_poll_timeout(addr, reg, reg & lock, 100, 70000));
39}
40EXPORT_SYMBOL_NS_GPL(ccu_helper_wait_for_lock, SUNXI_CCU);
41
42bool ccu_is_better_rate(struct ccu_common *common,
43			unsigned long target_rate,
44			unsigned long current_rate,
45			unsigned long best_rate)
46{
47	if (common->features & CCU_FEATURE_CLOSEST_RATE)
48		return abs(current_rate - target_rate) < abs(best_rate - target_rate);
49
50	return current_rate <= target_rate && current_rate > best_rate;
51}
52EXPORT_SYMBOL_NS_GPL(ccu_is_better_rate, SUNXI_CCU);
53
54/*
55 * This clock notifier is called when the frequency of a PLL clock is
56 * changed. In common PLL designs, changes to the dividers take effect
57 * almost immediately, while changes to the multipliers (implemented
58 * as dividers in the feedback loop) take a few cycles to work into
59 * the feedback loop for the PLL to stablize.
60 *
61 * Sometimes when the PLL clock rate is changed, the decrease in the
62 * divider is too much for the decrease in the multiplier to catch up.
63 * The PLL clock rate will spike, and in some cases, might lock up
64 * completely.
65 *
66 * This notifier callback will gate and then ungate the clock,
67 * effectively resetting it, so it proceeds to work. Care must be
68 * taken to reparent consumers to other temporary clocks during the
69 * rate change, and that this notifier callback must be the first
70 * to be registered.
71 */
72static int ccu_pll_notifier_cb(struct notifier_block *nb,
73			       unsigned long event, void *data)
74{
75	struct ccu_pll_nb *pll = to_ccu_pll_nb(nb);
76	int ret = 0;
77
78	if (event != POST_RATE_CHANGE)
79		goto out;
80
81	ccu_gate_helper_disable(pll->common, pll->enable);
82
83	ret = ccu_gate_helper_enable(pll->common, pll->enable);
84	if (ret)
85		goto out;
86
87	ccu_helper_wait_for_lock(pll->common, pll->lock);
88
89out:
90	return notifier_from_errno(ret);
91}
92
93int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
94{
95	pll_nb->clk_nb.notifier_call = ccu_pll_notifier_cb;
96
97	return clk_notifier_register(pll_nb->common->hw.clk,
98				     &pll_nb->clk_nb);
99}
100EXPORT_SYMBOL_NS_GPL(ccu_pll_notifier_register, SUNXI_CCU);
101
102static int sunxi_ccu_probe(struct sunxi_ccu *ccu, struct device *dev,
103			   struct device_node *node, void __iomem *reg,
104			   const struct sunxi_ccu_desc *desc)
105{
106	struct ccu_reset *reset;
107	int i, ret;
108
109	ccu->desc = desc;
110
111	spin_lock_init(&ccu->lock);
112
113	for (i = 0; i < desc->num_ccu_clks; i++) {
114		struct ccu_common *cclk = desc->ccu_clks[i];
115
116		if (!cclk)
117			continue;
118
119		cclk->base = reg;
120		cclk->lock = &ccu->lock;
121	}
122
123	for (i = 0; i < desc->hw_clks->num ; i++) {
124		struct clk_hw *hw = desc->hw_clks->hws[i];
125		const char *name;
126
127		if (!hw)
128			continue;
129
130		name = hw->init->name;
131		if (dev)
132			ret = clk_hw_register(dev, hw);
133		else
134			ret = of_clk_hw_register(node, hw);
135		if (ret) {
136			pr_err("Couldn't register clock %d - %s\n", i, name);
137			goto err_clk_unreg;
138		}
139	}
140
141	ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
142				     desc->hw_clks);
143	if (ret)
144		goto err_clk_unreg;
145
146	reset = &ccu->reset;
147	reset->rcdev.of_node = node;
148	reset->rcdev.ops = &ccu_reset_ops;
149	reset->rcdev.owner = dev ? dev->driver->owner : THIS_MODULE;
150	reset->rcdev.nr_resets = desc->num_resets;
151	reset->base = reg;
152	reset->lock = &ccu->lock;
153	reset->reset_map = desc->resets;
154
155	ret = reset_controller_register(&reset->rcdev);
156	if (ret)
157		goto err_del_provider;
158
159	return 0;
160
161err_del_provider:
162	of_clk_del_provider(node);
163err_clk_unreg:
164	while (--i >= 0) {
165		struct clk_hw *hw = desc->hw_clks->hws[i];
166
167		if (!hw)
168			continue;
169		clk_hw_unregister(hw);
170	}
171	return ret;
172}
173
174static void devm_sunxi_ccu_release(struct device *dev, void *res)
175{
176	struct sunxi_ccu *ccu = res;
177	const struct sunxi_ccu_desc *desc = ccu->desc;
178	int i;
179
180	reset_controller_unregister(&ccu->reset.rcdev);
181	of_clk_del_provider(dev->of_node);
182
183	for (i = 0; i < desc->hw_clks->num; i++) {
184		struct clk_hw *hw = desc->hw_clks->hws[i];
185
186		if (!hw)
187			continue;
188		clk_hw_unregister(hw);
189	}
190}
191
192int devm_sunxi_ccu_probe(struct device *dev, void __iomem *reg,
193			 const struct sunxi_ccu_desc *desc)
194{
195	struct sunxi_ccu *ccu;
196	int ret;
197
198	ccu = devres_alloc(devm_sunxi_ccu_release, sizeof(*ccu), GFP_KERNEL);
199	if (!ccu)
200		return -ENOMEM;
201
202	ret = sunxi_ccu_probe(ccu, dev, dev->of_node, reg, desc);
203	if (ret) {
204		devres_free(ccu);
205		return ret;
206	}
207
208	devres_add(dev, ccu);
209
210	return 0;
211}
212EXPORT_SYMBOL_NS_GPL(devm_sunxi_ccu_probe, SUNXI_CCU);
213
214void of_sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
215			const struct sunxi_ccu_desc *desc)
216{
217	struct sunxi_ccu *ccu;
218	int ret;
219
220	ccu = kzalloc(sizeof(*ccu), GFP_KERNEL);
221	if (!ccu)
222		return;
223
224	ret = sunxi_ccu_probe(ccu, NULL, node, reg, desc);
225	if (ret) {
226		pr_err("%pOF: probing clocks failed: %d\n", node, ret);
227		kfree(ccu);
228	}
229}
230
231MODULE_LICENSE("GPL");
232