1 /*
2 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
3 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
8 *
9 * Gated clock implementation
10 */
11
12 #include <linux/clk-provider.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
15 #include <linux/io.h>
16 #include <linux/err.h>
17 #include <linux/string.h>
18
19 /**
20 * DOC: basic gatable clock which can gate and ungate it's ouput
21 *
22 * Traits of this clock:
23 * prepare - clk_(un)prepare only ensures parent is (un)prepared
24 * enable - clk_enable and clk_disable are functional & control gating
25 * rate - inherits rate from parent. No clk_set_rate support
26 * parent - fixed parent. No clk_set_parent support
27 */
28
29 /*
30 * It works on following logic:
31 *
32 * For enabling clock, enable = 1
33 * set2dis = 1 -> clear bit -> set = 0
34 * set2dis = 0 -> set bit -> set = 1
35 *
36 * For disabling clock, enable = 0
37 * set2dis = 1 -> set bit -> set = 1
38 * set2dis = 0 -> clear bit -> set = 0
39 *
40 * So, result is always: enable xor set2dis.
41 */
clk_gate_endisable(struct clk_hw * hw,int enable)42 static void clk_gate_endisable(struct clk_hw *hw, int enable)
43 {
44 struct clk_gate *gate = to_clk_gate(hw);
45 int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
46 unsigned long flags;
47 u32 reg;
48
49 set ^= enable;
50
51 if (gate->lock)
52 spin_lock_irqsave(gate->lock, flags);
53 else
54 __acquire(gate->lock);
55
56 if (gate->flags & CLK_GATE_HIWORD_MASK) {
57 reg = BIT(gate->bit_idx + 16);
58 if (set)
59 reg |= BIT(gate->bit_idx);
60 } else {
61 reg = clk_readl(gate->reg);
62
63 if (set)
64 reg |= BIT(gate->bit_idx);
65 else
66 reg &= ~BIT(gate->bit_idx);
67 }
68
69 clk_writel(reg, gate->reg);
70
71 if (gate->lock)
72 spin_unlock_irqrestore(gate->lock, flags);
73 else
74 __release(gate->lock);
75 }
76
clk_gate_enable(struct clk_hw * hw)77 static int clk_gate_enable(struct clk_hw *hw)
78 {
79 clk_gate_endisable(hw, 1);
80
81 return 0;
82 }
83
clk_gate_disable(struct clk_hw * hw)84 static void clk_gate_disable(struct clk_hw *hw)
85 {
86 clk_gate_endisable(hw, 0);
87 }
88
clk_gate_is_enabled(struct clk_hw * hw)89 int clk_gate_is_enabled(struct clk_hw *hw)
90 {
91 u32 reg;
92 struct clk_gate *gate = to_clk_gate(hw);
93
94 reg = clk_readl(gate->reg);
95
96 /* if a set bit disables this clk, flip it before masking */
97 if (gate->flags & CLK_GATE_SET_TO_DISABLE)
98 reg ^= BIT(gate->bit_idx);
99
100 reg &= BIT(gate->bit_idx);
101
102 return reg ? 1 : 0;
103 }
104 EXPORT_SYMBOL_GPL(clk_gate_is_enabled);
105
106 const struct clk_ops clk_gate_ops = {
107 .enable = clk_gate_enable,
108 .disable = clk_gate_disable,
109 .is_enabled = clk_gate_is_enabled,
110 };
111 EXPORT_SYMBOL_GPL(clk_gate_ops);
112
113 /**
114 * clk_hw_register_gate - register a gate clock with the clock framework
115 * @dev: device that is registering this clock
116 * @name: name of this clock
117 * @parent_name: name of this clock's parent
118 * @flags: framework-specific flags for this clock
119 * @reg: register address to control gating of this clock
120 * @bit_idx: which bit in the register controls gating of this clock
121 * @clk_gate_flags: gate-specific flags for this clock
122 * @lock: shared register lock for this clock
123 */
clk_hw_register_gate(struct device * dev,const char * name,const char * parent_name,unsigned long flags,void __iomem * reg,u8 bit_idx,u8 clk_gate_flags,spinlock_t * lock)124 struct clk_hw *clk_hw_register_gate(struct device *dev, const char *name,
125 const char *parent_name, unsigned long flags,
126 void __iomem *reg, u8 bit_idx,
127 u8 clk_gate_flags, spinlock_t *lock)
128 {
129 struct clk_gate *gate;
130 struct clk_hw *hw;
131 struct clk_init_data init;
132 int ret;
133
134 if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
135 if (bit_idx > 15) {
136 pr_err("gate bit exceeds LOWORD field\n");
137 return ERR_PTR(-EINVAL);
138 }
139 }
140
141 /* allocate the gate */
142 gate = kzalloc(sizeof(*gate), GFP_KERNEL);
143 if (!gate)
144 return ERR_PTR(-ENOMEM);
145
146 init.name = name;
147 init.ops = &clk_gate_ops;
148 init.flags = flags | CLK_IS_BASIC;
149 init.parent_names = parent_name ? &parent_name : NULL;
150 init.num_parents = parent_name ? 1 : 0;
151
152 /* struct clk_gate assignments */
153 gate->reg = reg;
154 gate->bit_idx = bit_idx;
155 gate->flags = clk_gate_flags;
156 gate->lock = lock;
157 gate->hw.init = &init;
158
159 hw = &gate->hw;
160 ret = clk_hw_register(dev, hw);
161 if (ret) {
162 kfree(gate);
163 hw = ERR_PTR(ret);
164 }
165
166 return hw;
167 }
168 EXPORT_SYMBOL_GPL(clk_hw_register_gate);
169
clk_register_gate(struct device * dev,const char * name,const char * parent_name,unsigned long flags,void __iomem * reg,u8 bit_idx,u8 clk_gate_flags,spinlock_t * lock)170 struct clk *clk_register_gate(struct device *dev, const char *name,
171 const char *parent_name, unsigned long flags,
172 void __iomem *reg, u8 bit_idx,
173 u8 clk_gate_flags, spinlock_t *lock)
174 {
175 struct clk_hw *hw;
176
177 hw = clk_hw_register_gate(dev, name, parent_name, flags, reg,
178 bit_idx, clk_gate_flags, lock);
179 if (IS_ERR(hw))
180 return ERR_CAST(hw);
181 return hw->clk;
182 }
183 EXPORT_SYMBOL_GPL(clk_register_gate);
184
clk_unregister_gate(struct clk * clk)185 void clk_unregister_gate(struct clk *clk)
186 {
187 struct clk_gate *gate;
188 struct clk_hw *hw;
189
190 hw = __clk_get_hw(clk);
191 if (!hw)
192 return;
193
194 gate = to_clk_gate(hw);
195
196 clk_unregister(clk);
197 kfree(gate);
198 }
199 EXPORT_SYMBOL_GPL(clk_unregister_gate);
200
clk_hw_unregister_gate(struct clk_hw * hw)201 void clk_hw_unregister_gate(struct clk_hw *hw)
202 {
203 struct clk_gate *gate;
204
205 gate = to_clk_gate(hw);
206
207 clk_hw_unregister(hw);
208 kfree(gate);
209 }
210 EXPORT_SYMBOL_GPL(clk_hw_unregister_gate);
211