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1 | /* |
2 | * Clock Driver for Allo DAC | |
3 | * | |
4 | * Author: Baswaraj K <jaikumar@cem-solutions.net> | |
5 | * Copyright 2016 | |
6 | * based on code by Stuart MacLean | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License | |
10 | * version 2 as published by the Free Software Foundation. | |
11 | * | |
12 | * This program is distributed in the hope that it will be useful, but | |
13 | * WITHOUT ANY WARRANTY; without even the implied warranty of | |
14 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
15 | * General Public License for more details. | |
16 | */ | |
17 | ||
18 | #include <linux/clk-provider.h> | |
19 | #include <linux/clkdev.h> | |
20 | #include <linux/kernel.h> | |
21 | #include <linux/module.h> | |
22 | #include <linux/of.h> | |
23 | #include <linux/slab.h> | |
24 | #include <linux/platform_device.h> | |
25 | ||
26 | /* Clock rate of CLK44EN attached to GPIO6 pin */ | |
27 | #define CLK_44EN_RATE 45158400UL | |
28 | /* Clock rate of CLK48EN attached to GPIO3 pin */ | |
29 | #define CLK_48EN_RATE 49152000UL | |
30 | ||
31 | /** | |
32 | * struct allo_dac_clk - Common struct to the Allo DAC | |
33 | * @hw: clk_hw for the common clk framework | |
34 | * @mode: 0 => CLK44EN, 1 => CLK48EN | |
35 | */ | |
36 | struct clk_allo_hw { | |
37 | struct clk_hw hw; | |
38 | uint8_t mode; | |
39 | }; | |
40 | ||
41 | #define to_allo_clk(_hw) container_of(_hw, struct clk_allo_hw, hw) | |
42 | ||
43 | static const struct of_device_id clk_allo_dac_dt_ids[] = { | |
44 | { .compatible = "allo,dac-clk",}, | |
45 | { } | |
46 | }; | |
47 | MODULE_DEVICE_TABLE(of, clk_allo_dac_dt_ids); | |
48 | ||
49 | static unsigned long clk_allo_dac_recalc_rate(struct clk_hw *hw, | |
50 | unsigned long parent_rate) | |
51 | { | |
52 | return (to_allo_clk(hw)->mode == 0) ? CLK_44EN_RATE : | |
53 | CLK_48EN_RATE; | |
54 | } | |
55 | ||
56 | static long clk_allo_dac_round_rate(struct clk_hw *hw, | |
57 | unsigned long rate, unsigned long *parent_rate) | |
58 | { | |
59 | long actual_rate; | |
60 | ||
61 | if (rate <= CLK_44EN_RATE) { | |
62 | actual_rate = (long)CLK_44EN_RATE; | |
63 | } else if (rate >= CLK_48EN_RATE) { | |
64 | actual_rate = (long)CLK_48EN_RATE; | |
65 | } else { | |
66 | long diff44Rate = (long)(rate - CLK_44EN_RATE); | |
67 | long diff48Rate = (long)(CLK_48EN_RATE - rate); | |
68 | ||
69 | if (diff44Rate < diff48Rate) | |
70 | actual_rate = (long)CLK_44EN_RATE; | |
71 | else | |
72 | actual_rate = (long)CLK_48EN_RATE; | |
73 | } | |
74 | return actual_rate; | |
75 | } | |
76 | ||
77 | ||
78 | static int clk_allo_dac_set_rate(struct clk_hw *hw, | |
79 | unsigned long rate, unsigned long parent_rate) | |
80 | { | |
81 | unsigned long actual_rate; | |
82 | struct clk_allo_hw *clk = to_allo_clk(hw); | |
83 | ||
84 | actual_rate = (unsigned long)clk_allo_dac_round_rate(hw, rate, | |
85 | &parent_rate); | |
86 | clk->mode = (actual_rate == CLK_44EN_RATE) ? 0 : 1; | |
87 | return 0; | |
88 | } | |
89 | ||
90 | ||
91 | const struct clk_ops clk_allo_dac_rate_ops = { | |
92 | .recalc_rate = clk_allo_dac_recalc_rate, | |
93 | .round_rate = clk_allo_dac_round_rate, | |
94 | .set_rate = clk_allo_dac_set_rate, | |
95 | }; | |
96 | ||
97 | static int clk_allo_dac_probe(struct platform_device *pdev) | |
98 | { | |
99 | int ret; | |
100 | struct clk_allo_hw *proclk; | |
101 | struct clk *clk; | |
102 | struct device *dev; | |
103 | struct clk_init_data init; | |
104 | ||
105 | dev = &pdev->dev; | |
106 | ||
107 | proclk = kzalloc(sizeof(struct clk_allo_hw), GFP_KERNEL); | |
108 | if (!proclk) | |
109 | return -ENOMEM; | |
110 | ||
111 | init.name = "clk-allo-dac"; | |
112 | init.ops = &clk_allo_dac_rate_ops; | |
113 | init.flags = CLK_IS_BASIC; | |
114 | init.parent_names = NULL; | |
115 | init.num_parents = 0; | |
116 | ||
117 | proclk->mode = 0; | |
118 | proclk->hw.init = &init; | |
119 | ||
120 | clk = devm_clk_register(dev, &proclk->hw); | |
121 | if (!IS_ERR(clk)) { | |
122 | ret = of_clk_add_provider(dev->of_node, of_clk_src_simple_get, | |
123 | clk); | |
124 | } else { | |
125 | dev_err(dev, "Fail to register clock driver\n"); | |
126 | kfree(proclk); | |
127 | ret = PTR_ERR(clk); | |
128 | } | |
129 | return ret; | |
130 | } | |
131 | ||
132 | static int clk_allo_dac_remove(struct platform_device *pdev) | |
133 | { | |
134 | of_clk_del_provider(pdev->dev.of_node); | |
135 | return 0; | |
136 | } | |
137 | ||
138 | static struct platform_driver clk_allo_dac_driver = { | |
139 | .probe = clk_allo_dac_probe, | |
140 | .remove = clk_allo_dac_remove, | |
141 | .driver = { | |
142 | .name = "clk-allo-dac", | |
143 | .of_match_table = clk_allo_dac_dt_ids, | |
144 | }, | |
145 | }; | |
146 | ||
147 | static int __init clk_allo_dac_init(void) | |
148 | { | |
149 | return platform_driver_register(&clk_allo_dac_driver); | |
150 | } | |
151 | core_initcall(clk_allo_dac_init); | |
152 | ||
153 | static void __exit clk_allo_dac_exit(void) | |
154 | { | |
155 | platform_driver_unregister(&clk_allo_dac_driver); | |
156 | } | |
157 | module_exit(clk_allo_dac_exit); | |
158 | ||
159 | MODULE_DESCRIPTION("Allo DAC clock driver"); | |
160 | MODULE_LICENSE("GPL v2"); | |
161 | MODULE_ALIAS("platform:clk-allo-dac"); |