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