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 
19 struct sunxi_ccu {
20 	const struct sunxi_ccu_desc	*desc;
21 	spinlock_t			lock;
22 	struct ccu_reset		reset;
23 };
24 
25 void 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 }
40 EXPORT_SYMBOL_NS_GPL(ccu_helper_wait_for_lock, SUNXI_CCU);
41 
42 bool 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 }
52 EXPORT_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  */
72 static 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 
89 out:
90 	return notifier_from_errno(ret);
91 }
92 
93 int 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 }
100 EXPORT_SYMBOL_NS_GPL(ccu_pll_notifier_register, SUNXI_CCU);
101 
102 static 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 
161 err_del_provider:
162 	of_clk_del_provider(node);
163 err_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 
174 static 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 
192 int 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 }
212 EXPORT_SYMBOL_NS_GPL(devm_sunxi_ccu_probe, SUNXI_CCU);
213 
214 void 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 
231 MODULE_LICENSE("GPL");
232