xref: /openbmc/linux/drivers/clk/at91/clk-system.c (revision 2cf1c348)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
4  */
5 
6 #include <linux/clk-provider.h>
7 #include <linux/clkdev.h>
8 #include <linux/clk/at91_pmc.h>
9 #include <linux/of.h>
10 #include <linux/mfd/syscon.h>
11 #include <linux/regmap.h>
12 
13 #include "pmc.h"
14 
15 #define SYSTEM_MAX_ID		31
16 
17 #define SYSTEM_MAX_NAME_SZ	32
18 
19 #define to_clk_system(hw) container_of(hw, struct clk_system, hw)
20 struct clk_system {
21 	struct clk_hw hw;
22 	struct regmap *regmap;
23 	struct at91_clk_pms pms;
24 	u8 id;
25 };
26 
27 static inline int is_pck(int id)
28 {
29 	return (id >= 8) && (id <= 15);
30 }
31 
32 static inline bool clk_system_ready(struct regmap *regmap, int id)
33 {
34 	unsigned int status;
35 
36 	regmap_read(regmap, AT91_PMC_SR, &status);
37 
38 	return !!(status & (1 << id));
39 }
40 
41 static int clk_system_prepare(struct clk_hw *hw)
42 {
43 	struct clk_system *sys = to_clk_system(hw);
44 
45 	regmap_write(sys->regmap, AT91_PMC_SCER, 1 << sys->id);
46 
47 	if (!is_pck(sys->id))
48 		return 0;
49 
50 	while (!clk_system_ready(sys->regmap, sys->id))
51 		cpu_relax();
52 
53 	return 0;
54 }
55 
56 static void clk_system_unprepare(struct clk_hw *hw)
57 {
58 	struct clk_system *sys = to_clk_system(hw);
59 
60 	regmap_write(sys->regmap, AT91_PMC_SCDR, 1 << sys->id);
61 }
62 
63 static int clk_system_is_prepared(struct clk_hw *hw)
64 {
65 	struct clk_system *sys = to_clk_system(hw);
66 	unsigned int status;
67 
68 	regmap_read(sys->regmap, AT91_PMC_SCSR, &status);
69 
70 	if (!(status & (1 << sys->id)))
71 		return 0;
72 
73 	if (!is_pck(sys->id))
74 		return 1;
75 
76 	regmap_read(sys->regmap, AT91_PMC_SR, &status);
77 
78 	return !!(status & (1 << sys->id));
79 }
80 
81 static int clk_system_save_context(struct clk_hw *hw)
82 {
83 	struct clk_system *sys = to_clk_system(hw);
84 
85 	sys->pms.status = clk_system_is_prepared(hw);
86 
87 	return 0;
88 }
89 
90 static void clk_system_restore_context(struct clk_hw *hw)
91 {
92 	struct clk_system *sys = to_clk_system(hw);
93 
94 	if (sys->pms.status)
95 		clk_system_prepare(&sys->hw);
96 }
97 
98 static const struct clk_ops system_ops = {
99 	.prepare = clk_system_prepare,
100 	.unprepare = clk_system_unprepare,
101 	.is_prepared = clk_system_is_prepared,
102 	.save_context = clk_system_save_context,
103 	.restore_context = clk_system_restore_context,
104 };
105 
106 struct clk_hw * __init
107 at91_clk_register_system(struct regmap *regmap, const char *name,
108 			 const char *parent_name, u8 id)
109 {
110 	struct clk_system *sys;
111 	struct clk_hw *hw;
112 	struct clk_init_data init;
113 	int ret;
114 
115 	if (!parent_name || id > SYSTEM_MAX_ID)
116 		return ERR_PTR(-EINVAL);
117 
118 	sys = kzalloc(sizeof(*sys), GFP_KERNEL);
119 	if (!sys)
120 		return ERR_PTR(-ENOMEM);
121 
122 	init.name = name;
123 	init.ops = &system_ops;
124 	init.parent_names = &parent_name;
125 	init.num_parents = 1;
126 	init.flags = CLK_SET_RATE_PARENT;
127 
128 	sys->id = id;
129 	sys->hw.init = &init;
130 	sys->regmap = regmap;
131 
132 	hw = &sys->hw;
133 	ret = clk_hw_register(NULL, &sys->hw);
134 	if (ret) {
135 		kfree(sys);
136 		hw = ERR_PTR(ret);
137 	}
138 
139 	return hw;
140 }
141