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/iopoll.h>
11 #include <linux/slab.h>
12
13 #include "ccu_common.h"
14 #include "ccu_gate.h"
15 #include "ccu_reset.h"
16
17 static DEFINE_SPINLOCK(ccu_lock);
18
ccu_helper_wait_for_lock(struct ccu_common * common,u32 lock)19 void ccu_helper_wait_for_lock(struct ccu_common *common, u32 lock)
20 {
21 void __iomem *addr;
22 u32 reg;
23
24 if (!lock)
25 return;
26
27 if (common->features & CCU_FEATURE_LOCK_REG)
28 addr = common->base + common->lock_reg;
29 else
30 addr = common->base + common->reg;
31
32 WARN_ON(readl_relaxed_poll_timeout(addr, reg, reg & lock, 100, 70000));
33 }
34
35 /*
36 * This clock notifier is called when the frequency of a PLL clock is
37 * changed. In common PLL designs, changes to the dividers take effect
38 * almost immediately, while changes to the multipliers (implemented
39 * as dividers in the feedback loop) take a few cycles to work into
40 * the feedback loop for the PLL to stablize.
41 *
42 * Sometimes when the PLL clock rate is changed, the decrease in the
43 * divider is too much for the decrease in the multiplier to catch up.
44 * The PLL clock rate will spike, and in some cases, might lock up
45 * completely.
46 *
47 * This notifier callback will gate and then ungate the clock,
48 * effectively resetting it, so it proceeds to work. Care must be
49 * taken to reparent consumers to other temporary clocks during the
50 * rate change, and that this notifier callback must be the first
51 * to be registered.
52 */
ccu_pll_notifier_cb(struct notifier_block * nb,unsigned long event,void * data)53 static int ccu_pll_notifier_cb(struct notifier_block *nb,
54 unsigned long event, void *data)
55 {
56 struct ccu_pll_nb *pll = to_ccu_pll_nb(nb);
57 int ret = 0;
58
59 if (event != POST_RATE_CHANGE)
60 goto out;
61
62 ccu_gate_helper_disable(pll->common, pll->enable);
63
64 ret = ccu_gate_helper_enable(pll->common, pll->enable);
65 if (ret)
66 goto out;
67
68 ccu_helper_wait_for_lock(pll->common, pll->lock);
69
70 out:
71 return notifier_from_errno(ret);
72 }
73
ccu_pll_notifier_register(struct ccu_pll_nb * pll_nb)74 int ccu_pll_notifier_register(struct ccu_pll_nb *pll_nb)
75 {
76 pll_nb->clk_nb.notifier_call = ccu_pll_notifier_cb;
77
78 return clk_notifier_register(pll_nb->common->hw.clk,
79 &pll_nb->clk_nb);
80 }
81
sunxi_ccu_probe(struct device_node * node,void __iomem * reg,const struct sunxi_ccu_desc * desc)82 int sunxi_ccu_probe(struct device_node *node, void __iomem *reg,
83 const struct sunxi_ccu_desc *desc)
84 {
85 struct ccu_reset *reset;
86 int i, ret;
87
88 for (i = 0; i < desc->num_ccu_clks; i++) {
89 struct ccu_common *cclk = desc->ccu_clks[i];
90
91 if (!cclk)
92 continue;
93
94 cclk->base = reg;
95 cclk->lock = &ccu_lock;
96 }
97
98 for (i = 0; i < desc->hw_clks->num ; i++) {
99 struct clk_hw *hw = desc->hw_clks->hws[i];
100 const char *name;
101
102 if (!hw)
103 continue;
104
105 name = hw->init->name;
106 ret = of_clk_hw_register(node, hw);
107 if (ret) {
108 pr_err("Couldn't register clock %d - %s\n", i, name);
109 goto err_clk_unreg;
110 }
111 }
112
113 ret = of_clk_add_hw_provider(node, of_clk_hw_onecell_get,
114 desc->hw_clks);
115 if (ret)
116 goto err_clk_unreg;
117
118 reset = kzalloc(sizeof(*reset), GFP_KERNEL);
119 if (!reset) {
120 ret = -ENOMEM;
121 goto err_alloc_reset;
122 }
123
124 reset->rcdev.of_node = node;
125 reset->rcdev.ops = &ccu_reset_ops;
126 reset->rcdev.owner = THIS_MODULE;
127 reset->rcdev.nr_resets = desc->num_resets;
128 reset->base = reg;
129 reset->lock = &ccu_lock;
130 reset->reset_map = desc->resets;
131
132 ret = reset_controller_register(&reset->rcdev);
133 if (ret)
134 goto err_of_clk_unreg;
135
136 return 0;
137
138 err_of_clk_unreg:
139 kfree(reset);
140 err_alloc_reset:
141 of_clk_del_provider(node);
142 err_clk_unreg:
143 while (--i >= 0) {
144 struct clk_hw *hw = desc->hw_clks->hws[i];
145
146 if (!hw)
147 continue;
148 clk_hw_unregister(hw);
149 }
150 return ret;
151 }
152
