xref: /openbmc/linux/drivers/clk/at91/clk-h32mx.c (revision 7effbd18)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * clk-h32mx.c
4  *
5  *  Copyright (C) 2014 Atmel
6  *
7  * Alexandre Belloni <alexandre.belloni@free-electrons.com>
8  */
9 
10 #include <linux/clk-provider.h>
11 #include <linux/clkdev.h>
12 #include <linux/clk/at91_pmc.h>
13 #include <linux/of.h>
14 #include <linux/regmap.h>
15 #include <linux/mfd/syscon.h>
16 
17 #include "pmc.h"
18 
19 #define H32MX_MAX_FREQ	90000000
20 
21 struct clk_sama5d4_h32mx {
22 	struct clk_hw hw;
23 	struct regmap *regmap;
24 };
25 
26 #define to_clk_sama5d4_h32mx(hw) container_of(hw, struct clk_sama5d4_h32mx, hw)
27 
28 static unsigned long clk_sama5d4_h32mx_recalc_rate(struct clk_hw *hw,
29 						 unsigned long parent_rate)
30 {
31 	struct clk_sama5d4_h32mx *h32mxclk = to_clk_sama5d4_h32mx(hw);
32 	unsigned int mckr;
33 
34 	regmap_read(h32mxclk->regmap, AT91_PMC_MCKR, &mckr);
35 	if (mckr & AT91_PMC_H32MXDIV)
36 		return parent_rate / 2;
37 
38 	if (parent_rate > H32MX_MAX_FREQ)
39 		pr_warn("H32MX clock is too fast\n");
40 	return parent_rate;
41 }
42 
43 static long clk_sama5d4_h32mx_round_rate(struct clk_hw *hw, unsigned long rate,
44 				       unsigned long *parent_rate)
45 {
46 	unsigned long div;
47 
48 	if (rate > *parent_rate)
49 		return *parent_rate;
50 	div = *parent_rate / 2;
51 	if (rate < div)
52 		return div;
53 
54 	if (rate - div < *parent_rate - rate)
55 		return div;
56 
57 	return *parent_rate;
58 }
59 
60 static int clk_sama5d4_h32mx_set_rate(struct clk_hw *hw, unsigned long rate,
61 				    unsigned long parent_rate)
62 {
63 	struct clk_sama5d4_h32mx *h32mxclk = to_clk_sama5d4_h32mx(hw);
64 	u32 mckr = 0;
65 
66 	if (parent_rate != rate && (parent_rate / 2) != rate)
67 		return -EINVAL;
68 
69 	if ((parent_rate / 2) == rate)
70 		mckr = AT91_PMC_H32MXDIV;
71 
72 	regmap_update_bits(h32mxclk->regmap, AT91_PMC_MCKR,
73 			   AT91_PMC_H32MXDIV, mckr);
74 
75 	return 0;
76 }
77 
78 static const struct clk_ops h32mx_ops = {
79 	.recalc_rate = clk_sama5d4_h32mx_recalc_rate,
80 	.round_rate = clk_sama5d4_h32mx_round_rate,
81 	.set_rate = clk_sama5d4_h32mx_set_rate,
82 };
83 
84 struct clk_hw * __init
85 at91_clk_register_h32mx(struct regmap *regmap, const char *name,
86 			const char *parent_name)
87 {
88 	struct clk_sama5d4_h32mx *h32mxclk;
89 	struct clk_init_data init;
90 	int ret;
91 
92 	h32mxclk = kzalloc(sizeof(*h32mxclk), GFP_KERNEL);
93 	if (!h32mxclk)
94 		return ERR_PTR(-ENOMEM);
95 
96 	init.name = name;
97 	init.ops = &h32mx_ops;
98 	init.parent_names = parent_name ? &parent_name : NULL;
99 	init.num_parents = parent_name ? 1 : 0;
100 	init.flags = CLK_SET_RATE_GATE;
101 
102 	h32mxclk->hw.init = &init;
103 	h32mxclk->regmap = regmap;
104 
105 	ret = clk_hw_register(NULL, &h32mxclk->hw);
106 	if (ret) {
107 		kfree(h32mxclk);
108 		return ERR_PTR(ret);
109 	}
110 
111 	return &h32mxclk->hw;
112 }
113