summaryrefslogtreecommitdiffstats
path: root/drivers/clk/clk-gate.c
blob: f05823cd9b21117a0dd04f3d86a6a6f658cc983d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
 *
 * Gated clock implementation
 */

#include <linux/clk-provider.h>
#include <linux/module.h>
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/err.h>
#include <linux/string.h>

/**
 * DOC: basic gatable clock which can gate and ungate it's ouput
 *
 * Traits of this clock:
 * prepare - clk_(un)prepare only ensures parent is (un)prepared
 * enable - clk_enable and clk_disable are functional & control gating
 * rate - inherits rate from parent.  No clk_set_rate support
 * parent - fixed parent.  No clk_set_parent support
 */

/*
 * It works on following logic:
 *
 * For enabling clock, enable = 1
 *	set2dis = 1	-> clear bit	-> set = 0
 *	set2dis = 0	-> set bit	-> set = 1
 *
 * For disabling clock, enable = 0
 *	set2dis = 1	-> set bit	-> set = 1
 *	set2dis = 0	-> clear bit	-> set = 0
 *
 * So, result is always: enable xor set2dis.
 */
static void clk_gate_endisable(struct clk_hw *hw, int enable)
{
	struct clk_gate *gate = to_clk_gate(hw);
	int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
	unsigned long uninitialized_var(flags);
	u32 reg;

	set ^= enable;

	if (gate->lock)
		spin_lock_irqsave(gate->lock, flags);
	else
		__acquire(gate->lock);

	if (gate->flags & CLK_GATE_HIWORD_MASK) {
		reg = BIT(gate->bit_idx + 16);
		if (set)
			reg |= BIT(gate->bit_idx);
	} else {
		reg = clk_readl(gate->reg);

		if (set)
			reg |= BIT(gate->bit_idx);
		else
			reg &= ~BIT(gate->bit_idx);
	}

	clk_writel(reg, gate->reg);

	if (gate->lock)
		spin_unlock_irqrestore(gate->lock, flags);
	else
		__release(gate->lock);
}

static int clk_gate_enable(struct clk_hw *hw)
{
	clk_gate_endisable(hw, 1);

	return 0;
}

static void clk_gate_disable(struct clk_hw *hw)
{
	clk_gate_endisable(hw, 0);
}

int clk_gate_is_enabled(struct clk_hw *hw)
{
	u32 reg;
	struct clk_gate *gate = to_clk_gate(hw);

	reg = clk_readl(gate->reg);

	/* if a set bit disables this clk, flip it before masking */
	if (gate->flags & CLK_GATE_SET_TO_DISABLE)
		reg ^= BIT(gate->bit_idx);

	reg &= BIT(gate->bit_idx);

	return reg ? 1 : 0;
}
EXPORT_SYMBOL_GPL(clk_gate_is_enabled);

const struct clk_ops clk_gate_ops = {
	.enable = clk_gate_enable,
	.disable = clk_gate_disable,
	.is_enabled = clk_gate_is_enabled,
};
EXPORT_SYMBOL_GPL(clk_gate_ops);

/**
 * clk_hw_register_gate - register a gate clock with the clock framework
 * @dev: device that is registering this clock
 * @name: name of this clock
 * @parent_name: name of this clock's parent
 * @flags: framework-specific flags for this clock
 * @reg: register address to control gating of this clock
 * @bit_idx: which bit in the register controls gating of this clock
 * @clk_gate_flags: gate-specific flags for this clock
 * @lock: shared register lock for this clock
 */
struct clk_hw *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)
{
	struct clk_gate *gate;
	struct clk_hw *hw;
	struct clk_init_data init;
	int ret;

	if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
		if (bit_idx > 15) {
			pr_err("gate bit exceeds LOWORD field\n");
			return ERR_PTR(-EINVAL);
		}
	}

	/* allocate the gate */
	gate = kzalloc(sizeof(*gate), GFP_KERNEL);
	if (!gate)
		return ERR_PTR(-ENOMEM);

	init.name = name;
	init.ops = &clk_gate_ops;
	init.flags = flags | CLK_IS_BASIC;
	init.parent_names = parent_name ? &parent_name : NULL;
	init.num_parents = parent_name ? 1 : 0;

	/* struct clk_gate assignments */
	gate->reg = reg;
	gate->bit_idx = bit_idx;
	gate->flags = clk_gate_flags;
	gate->lock = lock;
	gate->hw.init = &init;

	hw = &gate->hw;
	ret = clk_hw_register(dev, hw);
	if (ret) {
		kfree(gate);
		hw = ERR_PTR(ret);
	}

	return hw;
}
EXPORT_SYMBOL_GPL(clk_hw_register_gate);

struct clk *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)
{
	struct clk_hw *hw;

	hw = clk_hw_register_gate(dev, name, parent_name, flags, reg,
				  bit_idx, clk_gate_flags, lock);
	if (IS_ERR(hw))
		return ERR_CAST(hw);
	return hw->clk;
}
EXPORT_SYMBOL_GPL(clk_register_gate);

void clk_unregister_gate(struct clk *clk)
{
	struct clk_gate *gate;
	struct clk_hw *hw;

	hw = __clk_get_hw(clk);
	if (!hw)
		return;

	gate = to_clk_gate(hw);

	clk_unregister(clk);
	kfree(gate);
}
EXPORT_SYMBOL_GPL(clk_unregister_gate);

void clk_hw_unregister_gate(struct clk_hw *hw)
{
	struct clk_gate *gate;

	gate = to_clk_gate(hw);

	clk_hw_unregister(hw);
	kfree(gate);
}
EXPORT_SYMBOL_GPL(clk_hw_unregister_gate);
OpenPOWER on IntegriCloud