1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright 2012 Freescale Semiconductor, Inc.
4 */
5
6#include <linux/clk-provider.h>
7#include <linux/err.h>
8#include <linux/io.h>
9#include <linux/slab.h>
10#include "clk.h"
11
12/**
13 * struct clk_ref - mxs reference clock
14 * @hw: clk_hw for the reference clock
15 * @reg: register address
16 * @idx: the index of the reference clock within the same register
17 *
18 * The mxs reference clock sources from pll. Every 4 reference clocks share
19 * one register space, and @idx is used to identify them. Each reference
20 * clock has a gate control and a fractional * divider. The rate is calculated
21 * as pll rate * (18 / FRAC), where FRAC = 18 ~ 35.
22 */
23struct clk_ref {
24 struct clk_hw hw;
25 void __iomem *reg;
26 u8 idx;
27};
28
29#define to_clk_ref(_hw) container_of(_hw, struct clk_ref, hw)
30
31static int clk_ref_enable(struct clk_hw *hw)
32{
33 struct clk_ref *ref = to_clk_ref(hw);
34
35 writel_relaxed(1 << ((ref->idx + 1) * 8 - 1), ref->reg + CLR);
36
37 return 0;
38}
39
40static void clk_ref_disable(struct clk_hw *hw)
41{
42 struct clk_ref *ref = to_clk_ref(hw);
43
44 writel_relaxed(1 << ((ref->idx + 1) * 8 - 1), ref->reg + SET);
45}
46
47static unsigned long clk_ref_recalc_rate(struct clk_hw *hw,
48 unsigned long parent_rate)
49{
50 struct clk_ref *ref = to_clk_ref(hw);
51 u64 tmp = parent_rate;
52 u8 frac = (readl_relaxed(ref->reg) >> (ref->idx * 8)) & 0x3f;
53
54 tmp *= 18;
55 do_div(tmp, frac);
56
57 return tmp;
58}
59
60static long clk_ref_round_rate(struct clk_hw *hw, unsigned long rate,
61 unsigned long *prate)
62{
63 unsigned long parent_rate = *prate;
64 u64 tmp = parent_rate;
65 u8 frac;
66
67 tmp = tmp * 18 + rate / 2;
68 do_div(tmp, rate);
69 frac = tmp;
70
71 if (frac < 18)
72 frac = 18;
73 else if (frac > 35)
74 frac = 35;
75
76 tmp = parent_rate;
77 tmp *= 18;
78 do_div(tmp, frac);
79
80 return tmp;
81}
82
83static int clk_ref_set_rate(struct clk_hw *hw, unsigned long rate,
84 unsigned long parent_rate)
85{
86 struct clk_ref *ref = to_clk_ref(hw);
87 unsigned long flags;
88 u64 tmp = parent_rate;
89 u32 val;
90 u8 frac, shift = ref->idx * 8;
91
92 tmp = tmp * 18 + rate / 2;
93 do_div(tmp, rate);
94 frac = tmp;
95
96 if (frac < 18)
97 frac = 18;
98 else if (frac > 35)
99 frac = 35;
100
101 spin_lock_irqsave(&mxs_lock, flags);
102
103 val = readl_relaxed(ref->reg);
104 val &= ~(0x3f << shift);
105 val |= frac << shift;
106 writel_relaxed(val, ref->reg);
107
108 spin_unlock_irqrestore(lock: &mxs_lock, flags);
109
110 return 0;
111}
112
113static const struct clk_ops clk_ref_ops = {
114 .enable = clk_ref_enable,
115 .disable = clk_ref_disable,
116 .recalc_rate = clk_ref_recalc_rate,
117 .round_rate = clk_ref_round_rate,
118 .set_rate = clk_ref_set_rate,
119};
120
121struct clk *mxs_clk_ref(const char *name, const char *parent_name,
122 void __iomem *reg, u8 idx)
123{
124 struct clk_ref *ref;
125 struct clk *clk;
126 struct clk_init_data init;
127
128 ref = kzalloc(size: sizeof(*ref), GFP_KERNEL);
129 if (!ref)
130 return ERR_PTR(error: -ENOMEM);
131
132 init.name = name;
133 init.ops = &clk_ref_ops;
134 init.flags = 0;
135 init.parent_names = (parent_name ? &parent_name: NULL);
136 init.num_parents = (parent_name ? 1 : 0);
137
138 ref->reg = reg;
139 ref->idx = idx;
140 ref->hw.init = &init;
141
142 clk = clk_register(NULL, hw: &ref->hw);
143 if (IS_ERR(ptr: clk))
144 kfree(objp: ref);
145
146 return clk;
147}
148

source code of linux/drivers/clk/mxs/clk-ref.c