1 /*
2  * Copyright 2014 Chen-Yu Tsai
3  *
4  * Chen-Yu Tsai <wens@csie.org>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  */
16 
17 #include <linux/clk.h>
18 #include <linux/clk-provider.h>
19 #include <linux/of_address.h>
20 
21 #include "clk-factors.h"
22 
23 /**
24  * sun8i_a23_get_mbus_factors() - calculates m factor for MBUS clocks
25  * MBUS rate is calculated as follows
26  * rate = parent_rate / (m + 1);
27  */
28 
29 static void sun8i_a23_get_mbus_factors(u32 *freq, u32 parent_rate,
30 				       u8 *n, u8 *k, u8 *m, u8 *p)
31 {
32 	u8 div;
33 
34 	/*
35 	 * These clocks can only divide, so we will never be able to
36 	 * achieve frequencies higher than the parent frequency
37 	 */
38 	if (*freq > parent_rate)
39 		*freq = parent_rate;
40 
41 	div = DIV_ROUND_UP(parent_rate, *freq);
42 
43 	if (div > 8)
44 		div = 8;
45 
46 	*freq = parent_rate / div;
47 
48 	/* we were called to round the frequency, we can now return */
49 	if (m == NULL)
50 		return;
51 
52 	*m = div - 1;
53 }
54 
55 static struct clk_factors_config sun8i_a23_mbus_config = {
56 	.mshift = 0,
57 	.mwidth = 3,
58 };
59 
60 static const struct factors_data sun8i_a23_mbus_data __initconst = {
61 	.enable = 31,
62 	.mux = 24,
63 	.muxmask = BIT(1) | BIT(0),
64 	.table = &sun8i_a23_mbus_config,
65 	.getter = sun8i_a23_get_mbus_factors,
66 };
67 
68 static DEFINE_SPINLOCK(sun8i_a23_mbus_lock);
69 
70 static void __init sun8i_a23_mbus_setup(struct device_node *node)
71 {
72 	struct clk *mbus;
73 	void __iomem *reg;
74 
75 	reg = of_iomap(node, 0);
76 	if (!reg) {
77 		pr_err("Could not get registers for a23-mbus-clk\n");
78 		return;
79 	}
80 
81 	mbus = sunxi_factors_register(node, &sun8i_a23_mbus_data,
82 				      &sun8i_a23_mbus_lock, reg);
83 
84 	/* The MBUS clocks needs to be always enabled */
85 	__clk_get(mbus);
86 	clk_prepare_enable(mbus);
87 }
88 CLK_OF_DECLARE(sun8i_a23_mbus, "allwinner,sun8i-a23-mbus-clk", sun8i_a23_mbus_setup);
89