blob: fe2ff9e774c289604aabb45552d2706b57a0ebfa [file] [log] [blame]
Mike Turquette9d9f78e2012-03-15 23:11:20 -07001/*
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#define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw)
30
31static void clk_gate_set_bit(struct clk_gate *gate)
32{
33 u32 reg;
34 unsigned long flags = 0;
35
36 if (gate->lock)
37 spin_lock_irqsave(gate->lock, flags);
38
39 reg = readl(gate->reg);
40 reg |= BIT(gate->bit_idx);
41 writel(reg, gate->reg);
42
43 if (gate->lock)
44 spin_unlock_irqrestore(gate->lock, flags);
45}
46
47static void clk_gate_clear_bit(struct clk_gate *gate)
48{
49 u32 reg;
50 unsigned long flags = 0;
51
52 if (gate->lock)
53 spin_lock_irqsave(gate->lock, flags);
54
55 reg = readl(gate->reg);
56 reg &= ~BIT(gate->bit_idx);
57 writel(reg, gate->reg);
58
59 if (gate->lock)
60 spin_unlock_irqrestore(gate->lock, flags);
61}
62
63static int clk_gate_enable(struct clk_hw *hw)
64{
65 struct clk_gate *gate = to_clk_gate(hw);
66
67 if (gate->flags & CLK_GATE_SET_TO_DISABLE)
68 clk_gate_clear_bit(gate);
69 else
70 clk_gate_set_bit(gate);
71
72 return 0;
73}
Mike Turquette9d9f78e2012-03-15 23:11:20 -070074
75static void clk_gate_disable(struct clk_hw *hw)
76{
77 struct clk_gate *gate = to_clk_gate(hw);
78
79 if (gate->flags & CLK_GATE_SET_TO_DISABLE)
80 clk_gate_set_bit(gate);
81 else
82 clk_gate_clear_bit(gate);
83}
Mike Turquette9d9f78e2012-03-15 23:11:20 -070084
85static int clk_gate_is_enabled(struct clk_hw *hw)
86{
87 u32 reg;
88 struct clk_gate *gate = to_clk_gate(hw);
89
90 reg = readl(gate->reg);
91
92 /* if a set bit disables this clk, flip it before masking */
93 if (gate->flags & CLK_GATE_SET_TO_DISABLE)
94 reg ^= BIT(gate->bit_idx);
95
96 reg &= BIT(gate->bit_idx);
97
98 return reg ? 1 : 0;
99}
Mike Turquette9d9f78e2012-03-15 23:11:20 -0700100
Shawn Guo822c2502012-03-27 15:23:22 +0800101const struct clk_ops clk_gate_ops = {
Mike Turquette9d9f78e2012-03-15 23:11:20 -0700102 .enable = clk_gate_enable,
103 .disable = clk_gate_disable,
104 .is_enabled = clk_gate_is_enabled,
105};
106EXPORT_SYMBOL_GPL(clk_gate_ops);
107
108struct clk *clk_register_gate(struct device *dev, const char *name,
109 const char *parent_name, unsigned long flags,
110 void __iomem *reg, u8 bit_idx,
111 u8 clk_gate_flags, spinlock_t *lock)
112{
113 struct clk_gate *gate;
114 struct clk *clk;
115
116 gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
117
118 if (!gate) {
119 pr_err("%s: could not allocate gated clk\n", __func__);
120 return NULL;
121 }
122
123 /* struct clk_gate assignments */
124 gate->reg = reg;
125 gate->bit_idx = bit_idx;
126 gate->flags = clk_gate_flags;
127 gate->lock = lock;
128
129 if (parent_name) {
130 gate->parent[0] = kstrdup(parent_name, GFP_KERNEL);
131 if (!gate->parent[0])
132 goto out;
133 }
134
135 clk = clk_register(dev, name,
136 &clk_gate_ops, &gate->hw,
137 gate->parent,
138 (parent_name ? 1 : 0),
139 flags);
140 if (clk)
141 return clk;
142out:
143 kfree(gate->parent[0]);
144 kfree(gate);
145
146 return NULL;
147}