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(common: pll->common, gate: pll->enable);
82
83 ret = ccu_gate_helper_enable(common: pll->common, gate: 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(err: 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(clk: pll_nb->common->hw.clk,
98 nb: &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(np: node, get: of_clk_hw_onecell_get,
142 data: 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(rcdev: &reset->rcdev);
156 if (ret)
157 goto err_del_provider;
158
159 return 0;
160
161err_del_provider:
162 of_clk_del_provider(np: 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(rcdev: &ccu->reset.rcdev);
181 of_clk_del_provider(np: 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, node: dev->of_node, reg, desc);
203 if (ret) {
204 devres_free(res: ccu);
205 return ret;
206 }
207
208 devres_add(dev, res: 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(size: 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(objp: ccu);
228 }
229}
230
231MODULE_LICENSE("GPL");
232

source code of linux/drivers/clk/sunxi-ng/ccu_common.c