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 #include <linux/regmap.h>
15 
16 #include "sun4i_hdmi.h"
17 
18 struct sun4i_ddc {
19 	struct clk_hw		hw;
20 	struct sun4i_hdmi	*hdmi;
21 	struct regmap_field	*reg;
22 	u8			pre_div;
23 	u8			m_offset;
24 };
25 
26 static inline struct sun4i_ddc *hw_to_ddc(struct clk_hw *hw)
27 {
28 	return container_of(hw, struct sun4i_ddc, hw);
29 }
30 
31 static unsigned long sun4i_ddc_calc_divider(unsigned long rate,
32 					    unsigned long parent_rate,
33 					    const u8 pre_div,
34 					    const u8 m_offset,
35 					    u8 *m, u8 *n)
36 {
37 	unsigned long best_rate = 0;
38 	u8 best_m = 0, best_n = 0, _m, _n;
39 
40 	for (_m = 0; _m < 8; _m++) {
41 		for (_n = 0; _n < 8; _n++) {
42 			unsigned long tmp_rate;
43 
44 			tmp_rate = (((parent_rate / pre_div) / 10) >> _n) /
45 				(_m + m_offset);
46 
47 			if (tmp_rate > rate)
48 				continue;
49 
50 			if (abs(rate - tmp_rate) < abs(rate - best_rate)) {
51 				best_rate = tmp_rate;
52 				best_m = _m;
53 				best_n = _n;
54 			}
55 		}
56 	}
57 
58 	if (m && n) {
59 		*m = best_m;
60 		*n = best_n;
61 	}
62 
63 	return best_rate;
64 }
65 
66 static long sun4i_ddc_round_rate(struct clk_hw *hw, unsigned long rate,
67 				 unsigned long *prate)
68 {
69 	struct sun4i_ddc *ddc = hw_to_ddc(hw);
70 
71 	return sun4i_ddc_calc_divider(rate, *prate, ddc->pre_div,
72 				      ddc->m_offset, NULL, NULL);
73 }
74 
75 static unsigned long sun4i_ddc_recalc_rate(struct clk_hw *hw,
76 					    unsigned long parent_rate)
77 {
78 	struct sun4i_ddc *ddc = hw_to_ddc(hw);
79 	unsigned int reg;
80 	u8 m, n;
81 
82 	regmap_field_read(ddc->reg, &reg);
83 	m = (reg >> 3) & 0xf;
84 	n = reg & 0x7;
85 
86 	return (((parent_rate / ddc->pre_div) / 10) >> n) /
87 	       (m + ddc->m_offset);
88 }
89 
90 static int sun4i_ddc_set_rate(struct clk_hw *hw, unsigned long rate,
91 			      unsigned long parent_rate)
92 {
93 	struct sun4i_ddc *ddc = hw_to_ddc(hw);
94 	u8 div_m, div_n;
95 
96 	sun4i_ddc_calc_divider(rate, parent_rate, ddc->pre_div,
97 			       ddc->m_offset, &div_m, &div_n);
98 
99 	regmap_field_write(ddc->reg,
100 			   SUN4I_HDMI_DDC_CLK_M(div_m) |
101 			   SUN4I_HDMI_DDC_CLK_N(div_n));
102 
103 	return 0;
104 }
105 
106 static const struct clk_ops sun4i_ddc_ops = {
107 	.recalc_rate	= sun4i_ddc_recalc_rate,
108 	.round_rate	= sun4i_ddc_round_rate,
109 	.set_rate	= sun4i_ddc_set_rate,
110 };
111 
112 int sun4i_ddc_create(struct sun4i_hdmi *hdmi, struct clk *parent)
113 {
114 	struct clk_init_data init;
115 	struct sun4i_ddc *ddc;
116 	const char *parent_name;
117 
118 	parent_name = __clk_get_name(parent);
119 	if (!parent_name)
120 		return -ENODEV;
121 
122 	ddc = devm_kzalloc(hdmi->dev, sizeof(*ddc), GFP_KERNEL);
123 	if (!ddc)
124 		return -ENOMEM;
125 
126 	ddc->reg = devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
127 					   hdmi->variant->ddc_clk_reg);
128 	if (IS_ERR(ddc->reg))
129 		return PTR_ERR(ddc->reg);
130 
131 	init.name = "hdmi-ddc";
132 	init.ops = &sun4i_ddc_ops;
133 	init.parent_names = &parent_name;
134 	init.num_parents = 1;
135 
136 	ddc->hdmi = hdmi;
137 	ddc->hw.init = &init;
138 	ddc->pre_div = hdmi->variant->ddc_clk_pre_divider;
139 	ddc->m_offset = hdmi->variant->ddc_clk_m_offset;
140 
141 	hdmi->ddc_clk = devm_clk_register(hdmi->dev, &ddc->hw);
142 	if (IS_ERR(hdmi->ddc_clk))
143 		return PTR_ERR(hdmi->ddc_clk);
144 
145 	return 0;
146 }
147