drivers/gpu/drm/sun4i/sun4i_hdmi_ddc_clk.c

   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 < 16; _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 }