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