Commit | Line | Data |
---|---|---|
270b9f42 VK |
1 | /* |
2 | * Copyright (C) 2012 ST Microelectronics | |
10d8935f | 3 | * Viresh Kumar <viresh.linux@gmail.com> |
270b9f42 VK |
4 | * |
5 | * This file is licensed under the terms of the GNU General Public | |
6 | * License version 2. This program is licensed "as is" without any | |
7 | * warranty of any kind, whether express or implied. | |
8 | * | |
9 | * Fractional Synthesizer clock implementation | |
10 | */ | |
11 | ||
12 | #define pr_fmt(fmt) "clk-frac-synth: " fmt | |
13 | ||
14 | #include <linux/clk-provider.h> | |
15 | #include <linux/slab.h> | |
16 | #include <linux/io.h> | |
17 | #include <linux/err.h> | |
18 | #include "clk.h" | |
19 | ||
20 | #define DIV_FACTOR_MASK 0x1FFFF | |
21 | ||
22 | /* | |
23 | * DOC: Fractional Synthesizer clock | |
24 | * | |
25 | * Fout from synthesizer can be given from below equation: | |
26 | * | |
27 | * Fout= Fin/2*div (division factor) | |
28 | * div is 17 bits:- | |
29 | * 0-13 (fractional part) | |
30 | * 14-16 (integer part) | |
31 | * div is (16-14 bits).(13-0 bits) (in binary) | |
32 | * | |
33 | * Fout = Fin/(2 * div) | |
34 | * Fout = ((Fin / 10000)/(2 * div)) * 10000 | |
35 | * Fout = (2^14 * (Fin / 10000)/(2^14 * (2 * div))) * 10000 | |
36 | * Fout = (((Fin / 10000) << 14)/(2 * (div << 14))) * 10000 | |
37 | * | |
38 | * div << 14 simply 17 bit value written at register. | |
39 | * Max error due to scaling down by 10000 is 10 KHz | |
40 | */ | |
41 | ||
42 | #define to_clk_frac(_hw) container_of(_hw, struct clk_frac, hw) | |
43 | ||
44 | static unsigned long frac_calc_rate(struct clk_hw *hw, unsigned long prate, | |
45 | int index) | |
46 | { | |
47 | struct clk_frac *frac = to_clk_frac(hw); | |
48 | struct frac_rate_tbl *rtbl = frac->rtbl; | |
49 | ||
50 | prate /= 10000; | |
51 | prate <<= 14; | |
52 | prate /= (2 * rtbl[index].div); | |
53 | prate *= 10000; | |
54 | ||
55 | return prate; | |
56 | } | |
57 | ||
58 | static long clk_frac_round_rate(struct clk_hw *hw, unsigned long drate, | |
59 | unsigned long *prate) | |
60 | { | |
61 | struct clk_frac *frac = to_clk_frac(hw); | |
62 | int unused; | |
63 | ||
64 | return clk_round_rate_index(hw, drate, *prate, frac_calc_rate, | |
65 | frac->rtbl_cnt, &unused); | |
66 | } | |
67 | ||
68 | static unsigned long clk_frac_recalc_rate(struct clk_hw *hw, | |
69 | unsigned long parent_rate) | |
70 | { | |
71 | struct clk_frac *frac = to_clk_frac(hw); | |
72 | unsigned long flags = 0; | |
73 | unsigned int div = 1, val; | |
74 | ||
75 | if (frac->lock) | |
76 | spin_lock_irqsave(frac->lock, flags); | |
77 | ||
78 | val = readl_relaxed(frac->reg); | |
79 | ||
80 | if (frac->lock) | |
81 | spin_unlock_irqrestore(frac->lock, flags); | |
82 | ||
83 | div = val & DIV_FACTOR_MASK; | |
84 | ||
85 | if (!div) | |
86 | return 0; | |
87 | ||
88 | parent_rate = parent_rate / 10000; | |
89 | ||
90 | parent_rate = (parent_rate << 14) / (2 * div); | |
91 | return parent_rate * 10000; | |
92 | } | |
93 | ||
94 | /* Configures new clock rate of frac */ | |
95 | static int clk_frac_set_rate(struct clk_hw *hw, unsigned long drate, | |
96 | unsigned long prate) | |
97 | { | |
98 | struct clk_frac *frac = to_clk_frac(hw); | |
99 | struct frac_rate_tbl *rtbl = frac->rtbl; | |
100 | unsigned long flags = 0, val; | |
101 | int i; | |
102 | ||
103 | clk_round_rate_index(hw, drate, prate, frac_calc_rate, frac->rtbl_cnt, | |
104 | &i); | |
105 | ||
106 | if (frac->lock) | |
107 | spin_lock_irqsave(frac->lock, flags); | |
108 | ||
109 | val = readl_relaxed(frac->reg) & ~DIV_FACTOR_MASK; | |
110 | val |= rtbl[i].div & DIV_FACTOR_MASK; | |
111 | writel_relaxed(val, frac->reg); | |
112 | ||
113 | if (frac->lock) | |
114 | spin_unlock_irqrestore(frac->lock, flags); | |
115 | ||
116 | return 0; | |
117 | } | |
118 | ||
119 | struct clk_ops clk_frac_ops = { | |
120 | .recalc_rate = clk_frac_recalc_rate, | |
121 | .round_rate = clk_frac_round_rate, | |
122 | .set_rate = clk_frac_set_rate, | |
123 | }; | |
124 | ||
125 | struct clk *clk_register_frac(const char *name, const char *parent_name, | |
126 | unsigned long flags, void __iomem *reg, | |
127 | struct frac_rate_tbl *rtbl, u8 rtbl_cnt, spinlock_t *lock) | |
128 | { | |
129 | struct clk_init_data init; | |
130 | struct clk_frac *frac; | |
131 | struct clk *clk; | |
132 | ||
133 | if (!name || !parent_name || !reg || !rtbl || !rtbl_cnt) { | |
134 | pr_err("Invalid arguments passed"); | |
135 | return ERR_PTR(-EINVAL); | |
136 | } | |
137 | ||
138 | frac = kzalloc(sizeof(*frac), GFP_KERNEL); | |
139 | if (!frac) { | |
140 | pr_err("could not allocate frac clk\n"); | |
141 | return ERR_PTR(-ENOMEM); | |
142 | } | |
143 | ||
144 | /* struct clk_frac assignments */ | |
145 | frac->reg = reg; | |
146 | frac->rtbl = rtbl; | |
147 | frac->rtbl_cnt = rtbl_cnt; | |
148 | frac->lock = lock; | |
149 | frac->hw.init = &init; | |
150 | ||
151 | init.name = name; | |
152 | init.ops = &clk_frac_ops; | |
153 | init.flags = flags; | |
154 | init.parent_names = &parent_name; | |
155 | init.num_parents = 1; | |
156 | ||
157 | clk = clk_register(NULL, &frac->hw); | |
158 | if (!IS_ERR_OR_NULL(clk)) | |
159 | return clk; | |
160 | ||
161 | pr_err("clk register failed\n"); | |
162 | kfree(frac); | |
163 | ||
164 | return NULL; | |
165 | } |