1 /*
2  * Copyright (C) 2016 Free Electrons
3  * Copyright (C) 2016 NextThing Co
4  *
5  * Maxime Ripard <maxime.ripard@free-electrons.com>
6  *
7  * This program is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU General Public License as
9  * published by the Free Software Foundation; either version 2 of
10  * the License, or (at your option) any later version.
11  */
12 
13 #include <linux/clk-provider.h>
14 
15 #include "sun4i_tcon.h"
16 #include "sun4i_hdmi.h"
17 
18 struct sun4i_ddc {
19 	struct clk_hw		hw;
20 	struct sun4i_hdmi	*hdmi;
21 };
22 
23 static inline struct sun4i_ddc *hw_to_ddc(struct clk_hw *hw)
24 {
25 	return container_of(hw, struct sun4i_ddc, hw);
26 }
27 
28 static unsigned long sun4i_ddc_calc_divider(unsigned long rate,
29 					    unsigned long parent_rate,
30 					    u8 *m, u8 *n)
31 {
32 	unsigned long best_rate = 0;
33 	u8 best_m = 0, best_n = 0, _m, _n;
34 
35 	for (_m = 0; _m < 8; _m++) {
36 		for (_n = 0; _n < 8; _n++) {
37 			unsigned long tmp_rate;
38 
39 			tmp_rate = (((parent_rate / 2) / 10) >> _n) / (_m + 1);
40 
41 			if (tmp_rate > rate)
42 				continue;
43 
44 			if (abs(rate - tmp_rate) < abs(rate - best_rate)) {
45 				best_rate = tmp_rate;
46 				best_m = _m;
47 				best_n = _n;
48 			}
49 		}
50 	}
51 
52 	if (m && n) {
53 		*m = best_m;
54 		*n = best_n;
55 	}
56 
57 	return best_rate;
58 }
59 
60 static long sun4i_ddc_round_rate(struct clk_hw *hw, unsigned long rate,
61 				 unsigned long *prate)
62 {
63 	return sun4i_ddc_calc_divider(rate, *prate, NULL, NULL);
64 }
65 
66 static unsigned long sun4i_ddc_recalc_rate(struct clk_hw *hw,
67 					    unsigned long parent_rate)
68 {
69 	struct sun4i_ddc *ddc = hw_to_ddc(hw);
70 	u32 reg;
71 	u8 m, n;
72 
73 	reg = readl(ddc->hdmi->base + SUN4I_HDMI_DDC_CLK_REG);
74 	m = (reg >> 3) & 0x7;
75 	n = reg & 0x7;
76 
77 	return (((parent_rate / 2) / 10) >> n) / (m + 1);
78 }
79 
80 static int sun4i_ddc_set_rate(struct clk_hw *hw, unsigned long rate,
81 			      unsigned long parent_rate)
82 {
83 	struct sun4i_ddc *ddc = hw_to_ddc(hw);
84 	u8 div_m, div_n;
85 
86 	sun4i_ddc_calc_divider(rate, parent_rate, &div_m, &div_n);
87 
88 	writel(SUN4I_HDMI_DDC_CLK_M(div_m) | SUN4I_HDMI_DDC_CLK_N(div_n),
89 	       ddc->hdmi->base + SUN4I_HDMI_DDC_CLK_REG);
90 
91 	return 0;
92 }
93 
94 static const struct clk_ops sun4i_ddc_ops = {
95 	.recalc_rate	= sun4i_ddc_recalc_rate,
96 	.round_rate	= sun4i_ddc_round_rate,
97 	.set_rate	= sun4i_ddc_set_rate,
98 };
99 
100 int sun4i_ddc_create(struct sun4i_hdmi *hdmi, struct clk *parent)
101 {
102 	struct clk_init_data init;
103 	struct sun4i_ddc *ddc;
104 	const char *parent_name;
105 
106 	parent_name = __clk_get_name(parent);
107 	if (!parent_name)
108 		return -ENODEV;
109 
110 	ddc = devm_kzalloc(hdmi->dev, sizeof(*ddc), GFP_KERNEL);
111 	if (!ddc)
112 		return -ENOMEM;
113 
114 	init.name = "hdmi-ddc";
115 	init.ops = &sun4i_ddc_ops;
116 	init.parent_names = &parent_name;
117 	init.num_parents = 1;
118 
119 	ddc->hdmi = hdmi;
120 	ddc->hw.init = &init;
121 
122 	hdmi->ddc_clk = devm_clk_register(hdmi->dev, &ddc->hw);
123 	if (IS_ERR(hdmi->ddc_clk))
124 		return PTR_ERR(hdmi->ddc_clk);
125 
126 	return 0;
127 }
128