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git.proxmox.com Git - mirror_ubuntu-eoan-kernel.git/blob - drivers/clk/spear/clk-frac-synth.c
2 * Copyright (C) 2012 ST Microelectronics
3 * Viresh Kumar <viresh.linux@gmail.com>
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.
9 * Fractional Synthesizer clock implementation
12 #define pr_fmt(fmt) "clk-frac-synth: " fmt
14 #include <linux/clk-provider.h>
15 #include <linux/slab.h>
17 #include <linux/err.h>
20 #define DIV_FACTOR_MASK 0x1FFFF
23 * DOC: Fractional Synthesizer clock
25 * Fout from synthesizer can be given from below equation:
27 * Fout= Fin/2*div (division factor)
29 * 0-13 (fractional part)
30 * 14-16 (integer part)
31 * div is (16-14 bits).(13-0 bits) (in binary)
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
38 * div << 14 simply 17 bit value written at register.
39 * Max error due to scaling down by 10000 is 10 KHz
42 #define to_clk_frac(_hw) container_of(_hw, struct clk_frac, hw)
44 static unsigned long frac_calc_rate(struct clk_hw
*hw
, unsigned long prate
,
47 struct clk_frac
*frac
= to_clk_frac(hw
);
48 struct frac_rate_tbl
*rtbl
= frac
->rtbl
;
52 prate
/= (2 * rtbl
[index
].div
);
58 static long clk_frac_round_rate(struct clk_hw
*hw
, unsigned long drate
,
61 struct clk_frac
*frac
= to_clk_frac(hw
);
64 return clk_round_rate_index(hw
, drate
, *prate
, frac_calc_rate
,
65 frac
->rtbl_cnt
, &unused
);
68 static unsigned long clk_frac_recalc_rate(struct clk_hw
*hw
,
69 unsigned long parent_rate
)
71 struct clk_frac
*frac
= to_clk_frac(hw
);
72 unsigned long flags
= 0;
73 unsigned int div
= 1, val
;
76 spin_lock_irqsave(frac
->lock
, flags
);
78 val
= readl_relaxed(frac
->reg
);
81 spin_unlock_irqrestore(frac
->lock
, flags
);
83 div
= val
& DIV_FACTOR_MASK
;
88 parent_rate
= parent_rate
/ 10000;
90 parent_rate
= (parent_rate
<< 14) / (2 * div
);
91 return parent_rate
* 10000;
94 /* Configures new clock rate of frac */
95 static int clk_frac_set_rate(struct clk_hw
*hw
, unsigned long drate
,
98 struct clk_frac
*frac
= to_clk_frac(hw
);
99 struct frac_rate_tbl
*rtbl
= frac
->rtbl
;
100 unsigned long flags
= 0, val
;
103 clk_round_rate_index(hw
, drate
, prate
, frac_calc_rate
, frac
->rtbl_cnt
,
107 spin_lock_irqsave(frac
->lock
, flags
);
109 val
= readl_relaxed(frac
->reg
) & ~DIV_FACTOR_MASK
;
110 val
|= rtbl
[i
].div
& DIV_FACTOR_MASK
;
111 writel_relaxed(val
, frac
->reg
);
114 spin_unlock_irqrestore(frac
->lock
, flags
);
119 static 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
,
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
)
129 struct clk_init_data init
;
130 struct clk_frac
*frac
;
133 if (!name
|| !parent_name
|| !reg
|| !rtbl
|| !rtbl_cnt
) {
134 pr_err("Invalid arguments passed");
135 return ERR_PTR(-EINVAL
);
138 frac
= kzalloc(sizeof(*frac
), GFP_KERNEL
);
140 pr_err("could not allocate frac clk\n");
141 return ERR_PTR(-ENOMEM
);
144 /* struct clk_frac assignments */
147 frac
->rtbl_cnt
= rtbl_cnt
;
149 frac
->hw
.init
= &init
;
152 init
.ops
= &clk_frac_ops
;
154 init
.parent_names
= &parent_name
;
155 init
.num_parents
= 1;
157 clk
= clk_register(NULL
, &frac
->hw
);
158 if (!IS_ERR_OR_NULL(clk
))
161 pr_err("clk register failed\n");