xref: /openbmc/linux/drivers/clk/imx/clk-gate2.c (revision 3dc4b6fb)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
4  * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
5  *
6  * Gated clock implementation
7  */
8 
9 #include <linux/clk-provider.h>
10 #include <linux/module.h>
11 #include <linux/slab.h>
12 #include <linux/io.h>
13 #include <linux/err.h>
14 #include <linux/string.h>
15 #include "clk.h"
16 
17 /**
18  * DOC: basic gatable clock which can gate and ungate it's ouput
19  *
20  * Traits of this clock:
21  * prepare - clk_(un)prepare only ensures parent is (un)prepared
22  * enable - clk_enable and clk_disable are functional & control gating
23  * rate - inherits rate from parent.  No clk_set_rate support
24  * parent - fixed parent.  No clk_set_parent support
25  */
26 
27 struct clk_gate2 {
28 	struct clk_hw hw;
29 	void __iomem	*reg;
30 	u8		bit_idx;
31 	u8		cgr_val;
32 	u8		flags;
33 	spinlock_t	*lock;
34 	unsigned int	*share_count;
35 };
36 
37 #define to_clk_gate2(_hw) container_of(_hw, struct clk_gate2, hw)
38 
39 static int clk_gate2_enable(struct clk_hw *hw)
40 {
41 	struct clk_gate2 *gate = to_clk_gate2(hw);
42 	u32 reg;
43 	unsigned long flags = 0;
44 
45 	spin_lock_irqsave(gate->lock, flags);
46 
47 	if (gate->share_count && (*gate->share_count)++ > 0)
48 		goto out;
49 
50 	reg = readl(gate->reg);
51 	reg &= ~(3 << gate->bit_idx);
52 	reg |= gate->cgr_val << gate->bit_idx;
53 	writel(reg, gate->reg);
54 
55 out:
56 	spin_unlock_irqrestore(gate->lock, flags);
57 
58 	return 0;
59 }
60 
61 static void clk_gate2_disable(struct clk_hw *hw)
62 {
63 	struct clk_gate2 *gate = to_clk_gate2(hw);
64 	u32 reg;
65 	unsigned long flags = 0;
66 
67 	spin_lock_irqsave(gate->lock, flags);
68 
69 	if (gate->share_count) {
70 		if (WARN_ON(*gate->share_count == 0))
71 			goto out;
72 		else if (--(*gate->share_count) > 0)
73 			goto out;
74 	}
75 
76 	reg = readl(gate->reg);
77 	reg &= ~(3 << gate->bit_idx);
78 	writel(reg, gate->reg);
79 
80 out:
81 	spin_unlock_irqrestore(gate->lock, flags);
82 }
83 
84 static int clk_gate2_reg_is_enabled(void __iomem *reg, u8 bit_idx)
85 {
86 	u32 val = readl(reg);
87 
88 	if (((val >> bit_idx) & 1) == 1)
89 		return 1;
90 
91 	return 0;
92 }
93 
94 static int clk_gate2_is_enabled(struct clk_hw *hw)
95 {
96 	struct clk_gate2 *gate = to_clk_gate2(hw);
97 
98 	return clk_gate2_reg_is_enabled(gate->reg, gate->bit_idx);
99 }
100 
101 static void clk_gate2_disable_unused(struct clk_hw *hw)
102 {
103 	struct clk_gate2 *gate = to_clk_gate2(hw);
104 	unsigned long flags = 0;
105 	u32 reg;
106 
107 	spin_lock_irqsave(gate->lock, flags);
108 
109 	if (!gate->share_count || *gate->share_count == 0) {
110 		reg = readl(gate->reg);
111 		reg &= ~(3 << gate->bit_idx);
112 		writel(reg, gate->reg);
113 	}
114 
115 	spin_unlock_irqrestore(gate->lock, flags);
116 }
117 
118 static const struct clk_ops clk_gate2_ops = {
119 	.enable = clk_gate2_enable,
120 	.disable = clk_gate2_disable,
121 	.disable_unused = clk_gate2_disable_unused,
122 	.is_enabled = clk_gate2_is_enabled,
123 };
124 
125 struct clk_hw *clk_hw_register_gate2(struct device *dev, const char *name,
126 		const char *parent_name, unsigned long flags,
127 		void __iomem *reg, u8 bit_idx, u8 cgr_val,
128 		u8 clk_gate2_flags, spinlock_t *lock,
129 		unsigned int *share_count)
130 {
131 	struct clk_gate2 *gate;
132 	struct clk_hw *hw;
133 	struct clk_init_data init;
134 	int ret;
135 
136 	gate = kzalloc(sizeof(struct clk_gate2), GFP_KERNEL);
137 	if (!gate)
138 		return ERR_PTR(-ENOMEM);
139 
140 	/* struct clk_gate2 assignments */
141 	gate->reg = reg;
142 	gate->bit_idx = bit_idx;
143 	gate->cgr_val = cgr_val;
144 	gate->flags = clk_gate2_flags;
145 	gate->lock = lock;
146 	gate->share_count = share_count;
147 
148 	init.name = name;
149 	init.ops = &clk_gate2_ops;
150 	init.flags = flags;
151 	init.parent_names = parent_name ? &parent_name : NULL;
152 	init.num_parents = parent_name ? 1 : 0;
153 
154 	gate->hw.init = &init;
155 	hw = &gate->hw;
156 
157 	ret = clk_hw_register(NULL, hw);
158 	if (ret) {
159 		kfree(gate);
160 		return ERR_PTR(ret);
161 	}
162 
163 	return hw;
164 }
165