drivers/gpu/drm/sun4i/sun4i_hdmi_ddc_clk.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2016 Free Electrons
   4  * Copyright (C) 2016 NextThing Co
   5  *
   6  * Maxime Ripard <maxime.ripard@free-electrons.com>
   7  */
   8
   9 #include <linux/clk-provider.h>
  10 #include <linux/regmap.h>
  11
  12 #include "sun4i_hdmi.h"
  13
  14 struct sun4i_ddc {
  15         struct clk_hw           hw;
  16         struct sun4i_hdmi       *hdmi;
  17         struct regmap_field     *reg;
  18         u8                      pre_div;
  19         u8                      m_offset;
  20 };
  21
  22 static inline struct sun4i_ddc *hw_to_ddc(struct clk_hw *hw)
  23 {
  24         return container_of(hw, struct sun4i_ddc, hw);
  25 }
  26
  27 static unsigned long sun4i_ddc_calc_divider(unsigned long rate,
  28                                             unsigned long parent_rate,
  29                                             const u8 pre_div,
  30                                             const u8 m_offset,
  31                                             u8 *m, u8 *n)
  32 {
  33         unsigned long best_rate = 0;
  34         u8 best_m = 0, best_n = 0, _m, _n;
  35
  36         for (_m = 0; _m < 16; _m++) {
  37                 for (_n = 0; _n < 8; _n++) {
  38                         unsigned long tmp_rate;
  39
  40                         tmp_rate = (((parent_rate / pre_div) / 10) >> _n) /
  41                                 (_m + m_offset);
  42
  43                         if (tmp_rate > rate)
  44                                 continue;
  45
  46                         if (abs(rate - tmp_rate) < abs(rate - best_rate)) {
  47                                 best_rate = tmp_rate;
  48                                 best_m = _m;
  49                                 best_n = _n;
  50                         }
  51                 }
  52         }
  53
  54         if (m && n) {
  55                 *m = best_m;
  56                 *n = best_n;
  57         }
  58
  59         return best_rate;
  60 }
  61
  62 static long sun4i_ddc_round_rate(struct clk_hw *hw, unsigned long rate,
  63                                  unsigned long *prate)
  64 {
  65         struct sun4i_ddc *ddc = hw_to_ddc(hw);
  66
  67         return sun4i_ddc_calc_divider(rate, *prate, ddc->pre_div,
  68                                       ddc->m_offset, NULL, NULL);
  69 }
  70
  71 static unsigned long sun4i_ddc_recalc_rate(struct clk_hw *hw,
  72                                             unsigned long parent_rate)
  73 {
  74         struct sun4i_ddc *ddc = hw_to_ddc(hw);
  75         unsigned int reg;
  76         u8 m, n;
  77
  78         regmap_field_read(ddc->reg, &reg);
  79         m = (reg >> 3) & 0xf;
  80         n = reg & 0x7;
  81
  82         return (((parent_rate / ddc->pre_div) / 10) >> n) /
  83                (m + ddc->m_offset);
  84 }
  85
  86 static int sun4i_ddc_set_rate(struct clk_hw *hw, unsigned long rate,
  87                               unsigned long parent_rate)
  88 {
  89         struct sun4i_ddc *ddc = hw_to_ddc(hw);
  90         u8 div_m, div_n;
  91
  92         sun4i_ddc_calc_divider(rate, parent_rate, ddc->pre_div,
  93                                ddc->m_offset, &div_m, &div_n);
  94
  95         regmap_field_write(ddc->reg,
  96                            SUN4I_HDMI_DDC_CLK_M(div_m) |
  97                            SUN4I_HDMI_DDC_CLK_N(div_n));
  98
  99         return 0;
 100 }
 101
 102 static const struct clk_ops sun4i_ddc_ops = {
 103         .recalc_rate    = sun4i_ddc_recalc_rate,
 104         .round_rate     = sun4i_ddc_round_rate,
 105         .set_rate       = sun4i_ddc_set_rate,
 106 };
 107
 108 int sun4i_ddc_create(struct sun4i_hdmi *hdmi, struct clk *parent)
 109 {
 110         struct clk_init_data init;
 111         struct sun4i_ddc *ddc;
 112         const char *parent_name;
 113
 114         parent_name = __clk_get_name(parent);
 115         if (!parent_name)
 116                 return -ENODEV;
 117
 118         ddc = devm_kzalloc(hdmi->dev, sizeof(*ddc), GFP_KERNEL);
 119         if (!ddc)
 120                 return -ENOMEM;
 121
 122         ddc->reg = devm_regmap_field_alloc(hdmi->dev, hdmi->regmap,
 123                                            hdmi->variant->ddc_clk_reg);
 124         if (IS_ERR(ddc->reg))
 125                 return PTR_ERR(ddc->reg);
 126
 127         init.name = "hdmi-ddc";
 128         init.ops = &sun4i_ddc_ops;
 129         init.parent_names = &parent_name;
 130         init.num_parents = 1;
 131
 132         ddc->hdmi = hdmi;
 133         ddc->hw.init = &init;
 134         ddc->pre_div = hdmi->variant->ddc_clk_pre_divider;
 135         ddc->m_offset = hdmi->variant->ddc_clk_m_offset;
 136
 137         hdmi->ddc_clk = devm_clk_register(hdmi->dev, &ddc->hw);
 138         if (IS_ERR(hdmi->ddc_clk))
 139                 return PTR_ERR(hdmi->ddc_clk);
 140
 141         return 0;
 142 }