2 * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
3 * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
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.
9 * Gated clock implementation
12 #include <linux/clk-provider.h>
13 #include <linux/module.h>
14 #include <linux/slab.h>
16 #include <linux/err.h>
17 #include <linux/string.h>
20 * DOC: basic gatable clock which can gate and ungate it's ouput
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
29 #define to_clk_gate(_hw) container_of(_hw, struct clk_gate, hw)
31 static void clk_gate_set_bit(struct clk_gate *gate)
34 unsigned long flags = 0;
37 spin_lock_irqsave(gate->lock, flags);
39 reg = readl(gate->reg);
40 reg |= BIT(gate->bit_idx);
41 writel(reg, gate->reg);
44 spin_unlock_irqrestore(gate->lock, flags);
47 static void clk_gate_clear_bit(struct clk_gate *gate)
50 unsigned long flags = 0;
53 spin_lock_irqsave(gate->lock, flags);
55 reg = readl(gate->reg);
56 reg &= ~BIT(gate->bit_idx);
57 writel(reg, gate->reg);
60 spin_unlock_irqrestore(gate->lock, flags);
63 static int clk_gate_enable(struct clk_hw *hw)
65 struct clk_gate *gate = to_clk_gate(hw);
67 if (gate->flags & CLK_GATE_SET_TO_DISABLE)
68 clk_gate_clear_bit(gate);
70 clk_gate_set_bit(gate);
75 static void clk_gate_disable(struct clk_hw *hw)
77 struct clk_gate *gate = to_clk_gate(hw);
79 if (gate->flags & CLK_GATE_SET_TO_DISABLE)
80 clk_gate_set_bit(gate);
82 clk_gate_clear_bit(gate);
85 static int clk_gate_is_enabled(struct clk_hw *hw)
88 struct clk_gate *gate = to_clk_gate(hw);
90 reg = readl(gate->reg);
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);
96 reg &= BIT(gate->bit_idx);
101 const struct clk_ops clk_gate_ops = {
102 .enable = clk_gate_enable,
103 .disable = clk_gate_disable,
104 .is_enabled = clk_gate_is_enabled,
106 EXPORT_SYMBOL_GPL(clk_gate_ops);
109 * clk_register_gate - register a gate clock with the clock framework
110 * @dev: device that is registering this clock
111 * @name: name of this clock
112 * @parent_name: name of this clock's parent
113 * @flags: framework-specific flags for this clock
114 * @reg: register address to control gating of this clock
115 * @bit_idx: which bit in the register controls gating of this clock
116 * @clk_gate_flags: gate-specific flags for this clock
117 * @lock: shared register lock for this clock
119 struct clk *clk_register_gate(struct device *dev, const char *name,
120 const char *parent_name, unsigned long flags,
121 void __iomem *reg, u8 bit_idx,
122 u8 clk_gate_flags, spinlock_t *lock)
124 struct clk_gate *gate;
127 /* allocate the gate */
128 gate = kzalloc(sizeof(struct clk_gate), GFP_KERNEL);
130 pr_err("%s: could not allocate gated clk\n", __func__);
131 return ERR_PTR(-ENOMEM);
134 /* struct clk_gate assignments */
136 gate->bit_idx = bit_idx;
137 gate->flags = clk_gate_flags;
140 /* register the clock */
141 clk = clk_register(dev, name,
142 &clk_gate_ops, &gate->hw,
143 (parent_name ? &parent_name : NULL),
144 (parent_name ? 1 : 0),