xref: /openbmc/linux/drivers/clk/clk-gate.c (revision 815f0e73)
1 // SPDX-License-Identifier: GPL-2.0
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/device.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/io.h>
14 #include <linux/err.h>
15 #include <linux/string.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 
clk_gate_readl(struct clk_gate * gate)27 static inline u32 clk_gate_readl(struct clk_gate *gate)
28 {
29 	if (gate->flags & CLK_GATE_BIG_ENDIAN)
30 		return ioread32be(gate->reg);
31 
32 	return readl(gate->reg);
33 }
34 
clk_gate_writel(struct clk_gate * gate,u32 val)35 static inline void clk_gate_writel(struct clk_gate *gate, u32 val)
36 {
37 	if (gate->flags & CLK_GATE_BIG_ENDIAN)
38 		iowrite32be(val, gate->reg);
39 	else
40 		writel(val, gate->reg);
41 }
42 
43 /*
44  * It works on following logic:
45  *
46  * For enabling clock, enable = 1
47  *	set2dis = 1	-> clear bit	-> set = 0
48  *	set2dis = 0	-> set bit	-> set = 1
49  *
50  * For disabling clock, enable = 0
51  *	set2dis = 1	-> set bit	-> set = 1
52  *	set2dis = 0	-> clear bit	-> set = 0
53  *
54  * So, result is always: enable xor set2dis.
55  */
clk_gate_endisable(struct clk_hw * hw,int enable)56 static void clk_gate_endisable(struct clk_hw *hw, int enable)
57 {
58 	struct clk_gate *gate = to_clk_gate(hw);
59 	int set = gate->flags & CLK_GATE_SET_TO_DISABLE ? 1 : 0;
60 	unsigned long flags;
61 	u32 reg;
62 
63 	set ^= enable;
64 
65 	if (gate->lock)
66 		spin_lock_irqsave(gate->lock, flags);
67 	else
68 		__acquire(gate->lock);
69 
70 	if (gate->flags & CLK_GATE_HIWORD_MASK) {
71 		reg = BIT(gate->bit_idx + 16);
72 		if (set)
73 			reg |= BIT(gate->bit_idx);
74 	} else {
75 		reg = clk_gate_readl(gate);
76 
77 		if (set)
78 			reg |= BIT(gate->bit_idx);
79 		else
80 			reg &= ~BIT(gate->bit_idx);
81 	}
82 
83 	clk_gate_writel(gate, reg);
84 
85 	if (gate->lock)
86 		spin_unlock_irqrestore(gate->lock, flags);
87 	else
88 		__release(gate->lock);
89 }
90 
clk_gate_enable(struct clk_hw * hw)91 static int clk_gate_enable(struct clk_hw *hw)
92 {
93 	clk_gate_endisable(hw, 1);
94 
95 	return 0;
96 }
97 
clk_gate_disable(struct clk_hw * hw)98 static void clk_gate_disable(struct clk_hw *hw)
99 {
100 	clk_gate_endisable(hw, 0);
101 }
102 
clk_gate_is_enabled(struct clk_hw * hw)103 int clk_gate_is_enabled(struct clk_hw *hw)
104 {
105 	u32 reg;
106 	struct clk_gate *gate = to_clk_gate(hw);
107 
108 	reg = clk_gate_readl(gate);
109 
110 	/* if a set bit disables this clk, flip it before masking */
111 	if (gate->flags & CLK_GATE_SET_TO_DISABLE)
112 		reg ^= BIT(gate->bit_idx);
113 
114 	reg &= BIT(gate->bit_idx);
115 
116 	return reg ? 1 : 0;
117 }
118 EXPORT_SYMBOL_GPL(clk_gate_is_enabled);
119 
120 const struct clk_ops clk_gate_ops = {
121 	.enable = clk_gate_enable,
122 	.disable = clk_gate_disable,
123 	.is_enabled = clk_gate_is_enabled,
124 };
125 EXPORT_SYMBOL_GPL(clk_gate_ops);
126 
__clk_hw_register_gate(struct device * dev,struct device_node * np,const char * name,const char * parent_name,const struct clk_hw * parent_hw,const struct clk_parent_data * parent_data,unsigned long flags,void __iomem * reg,u8 bit_idx,u8 clk_gate_flags,spinlock_t * lock)127 struct clk_hw *__clk_hw_register_gate(struct device *dev,
128 		struct device_node *np, const char *name,
129 		const char *parent_name, const struct clk_hw *parent_hw,
130 		const struct clk_parent_data *parent_data,
131 		unsigned long flags,
132 		void __iomem *reg, u8 bit_idx,
133 		u8 clk_gate_flags, spinlock_t *lock)
134 {
135 	struct clk_gate *gate;
136 	struct clk_hw *hw;
137 	struct clk_init_data init = {};
138 	int ret = -EINVAL;
139 
140 	if (clk_gate_flags & CLK_GATE_HIWORD_MASK) {
141 		if (bit_idx > 15) {
142 			pr_err("gate bit exceeds LOWORD field\n");
143 			return ERR_PTR(-EINVAL);
144 		}
145 	}
146 
147 	/* allocate the gate */
148 	gate = kzalloc(sizeof(*gate), GFP_KERNEL);
149 	if (!gate)
150 		return ERR_PTR(-ENOMEM);
151 
152 	init.name = name;
153 	init.ops = &clk_gate_ops;
154 	init.flags = flags;
155 	init.parent_names = parent_name ? &parent_name : NULL;
156 	init.parent_hws = parent_hw ? &parent_hw : NULL;
157 	init.parent_data = parent_data;
158 	if (parent_name || parent_hw || parent_data)
159 		init.num_parents = 1;
160 	else
161 		init.num_parents = 0;
162 
163 	/* struct clk_gate assignments */
164 	gate->reg = reg;
165 	gate->bit_idx = bit_idx;
166 	gate->flags = clk_gate_flags;
167 	gate->lock = lock;
168 	gate->hw.init = &init;
169 
170 	hw = &gate->hw;
171 	if (dev || !np)
172 		ret = clk_hw_register(dev, hw);
173 	else if (np)
174 		ret = of_clk_hw_register(np, hw);
175 	if (ret) {
176 		kfree(gate);
177 		hw = ERR_PTR(ret);
178 	}
179 
180 	return hw;
181 
182 }
183 EXPORT_SYMBOL_GPL(__clk_hw_register_gate);
184 
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)185 struct clk *clk_register_gate(struct device *dev, const char *name,
186 		const char *parent_name, unsigned long flags,
187 		void __iomem *reg, u8 bit_idx,
188 		u8 clk_gate_flags, spinlock_t *lock)
189 {
190 	struct clk_hw *hw;
191 
192 	hw = clk_hw_register_gate(dev, name, parent_name, flags, reg,
193 				  bit_idx, clk_gate_flags, lock);
194 	if (IS_ERR(hw))
195 		return ERR_CAST(hw);
196 	return hw->clk;
197 }
198 EXPORT_SYMBOL_GPL(clk_register_gate);
199 
clk_unregister_gate(struct clk * clk)200 void clk_unregister_gate(struct clk *clk)
201 {
202 	struct clk_gate *gate;
203 	struct clk_hw *hw;
204 
205 	hw = __clk_get_hw(clk);
206 	if (!hw)
207 		return;
208 
209 	gate = to_clk_gate(hw);
210 
211 	clk_unregister(clk);
212 	kfree(gate);
213 }
214 EXPORT_SYMBOL_GPL(clk_unregister_gate);
215 
clk_hw_unregister_gate(struct clk_hw * hw)216 void clk_hw_unregister_gate(struct clk_hw *hw)
217 {
218 	struct clk_gate *gate;
219 
220 	gate = to_clk_gate(hw);
221 
222 	clk_hw_unregister(hw);
223 	kfree(gate);
224 }
225 EXPORT_SYMBOL_GPL(clk_hw_unregister_gate);
226 
devm_clk_hw_release_gate(struct device * dev,void * res)227 static void devm_clk_hw_release_gate(struct device *dev, void *res)
228 {
229 	clk_hw_unregister_gate(*(struct clk_hw **)res);
230 }
231 
__devm_clk_hw_register_gate(struct device * dev,struct device_node * np,const char * name,const char * parent_name,const struct clk_hw * parent_hw,const struct clk_parent_data * parent_data,unsigned long flags,void __iomem * reg,u8 bit_idx,u8 clk_gate_flags,spinlock_t * lock)232 struct clk_hw *__devm_clk_hw_register_gate(struct device *dev,
233 		struct device_node *np, const char *name,
234 		const char *parent_name, const struct clk_hw *parent_hw,
235 		const struct clk_parent_data *parent_data,
236 		unsigned long flags,
237 		void __iomem *reg, u8 bit_idx,
238 		u8 clk_gate_flags, spinlock_t *lock)
239 {
240 	struct clk_hw **ptr, *hw;
241 
242 	ptr = devres_alloc(devm_clk_hw_release_gate, sizeof(*ptr), GFP_KERNEL);
243 	if (!ptr)
244 		return ERR_PTR(-ENOMEM);
245 
246 	hw = __clk_hw_register_gate(dev, np, name, parent_name, parent_hw,
247 				    parent_data, flags, reg, bit_idx,
248 				    clk_gate_flags, lock);
249 
250 	if (!IS_ERR(hw)) {
251 		*ptr = hw;
252 		devres_add(dev, ptr);
253 	} else {
254 		devres_free(ptr);
255 	}
256 
257 	return hw;
258 }
259 EXPORT_SYMBOL_GPL(__devm_clk_hw_register_gate);
260