drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_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_hdmi.h"
  16
  17 struct sun4i_tmds {
  18         struct clk_hw           hw;
  19         struct sun4i_hdmi       *hdmi;
  20
  21         u8                      div_offset;
  22 };
  23
  24 static inline struct sun4i_tmds *hw_to_tmds(struct clk_hw *hw)
  25 {
  26         return container_of(hw, struct sun4i_tmds, hw);
  27 }
  28
  29
  30 static unsigned long sun4i_tmds_calc_divider(unsigned long rate,
  31                                              unsigned long parent_rate,
  32                                              u8 div_offset,
  33                                              u8 *div,
  34                                              bool *half)
  35 {
  36         unsigned long best_rate = 0;
  37         u8 best_m = 0, m;
  38         bool is_double = false;
  39
  40         for (m = div_offset ?: 1; m < (16 + div_offset); m++) {
  41                 u8 d;
  42
  43                 for (d = 1; d < 3; d++) {
  44                         unsigned long tmp_rate;
  45
  46                         tmp_rate = parent_rate / m / d;
  47
  48                         if (tmp_rate > rate)
  49                                 continue;
  50
  51                         if (!best_rate ||
  52                             (rate - tmp_rate) < (rate - best_rate)) {
  53                                 best_rate = tmp_rate;
  54                                 best_m = m;
  55                                 is_double = (d == 2) ? true : false;
  56                         }
  57                 }
  58         }
  59
  60         if (div && half) {
  61                 *div = best_m;
  62                 *half = is_double;
  63         }
  64
  65         return best_rate;
  66 }
  67
  68
  69 static int sun4i_tmds_determine_rate(struct clk_hw *hw,
  70                                      struct clk_rate_request *req)
  71 {
  72         struct sun4i_tmds *tmds = hw_to_tmds(hw);
  73         struct clk_hw *parent = NULL;
  74         unsigned long best_parent = 0;
  75         unsigned long rate = req->rate;
  76         int best_div = 1, best_half = 1;
  77         int i, j, p;
  78
  79         /*
  80          * We only consider PLL3, since the TCON is very likely to be
  81          * clocked from it, and to have the same rate than our HDMI
  82          * clock, so we should not need to do anything.
  83          */
  84
  85         for (p = 0; p < clk_hw_get_num_parents(hw); p++) {
  86                 parent = clk_hw_get_parent_by_index(hw, p);
  87                 if (!parent)
  88                         continue;
  89
  90                 for (i = 1; i < 3; i++) {
  91                         for (j = tmds->div_offset ?: 1;
  92                              j < (16 + tmds->div_offset); j++) {
  93                                 unsigned long ideal = rate * i * j;
  94                                 unsigned long rounded;
  95
  96                                 rounded = clk_hw_round_rate(parent, ideal);
  97
  98                                 if (rounded == ideal) {
  99                                         best_parent = rounded;
 100                                         best_half = i;
 101                                         best_div = j;
 102                                         goto out;
 103                                 }
 104
 105                                 if (!best_parent ||
 106                                     abs(rate - rounded / i / j) <
 107                                     abs(rate - best_parent / best_half /
 108                                         best_div)) {
 109                                         best_parent = rounded;
 110                                         best_half = i;
 111                                         best_div = j;
 112                                 }
 113                         }
 114                 }
 115         }
 116
 117         if (!parent)
 118                 return -EINVAL;
 119
 120 out:
 121         req->rate = best_parent / best_half / best_div;
 122         req->best_parent_rate = best_parent;
 123         req->best_parent_hw = parent;
 124
 125         return 0;
 126 }
 127
 128 static unsigned long sun4i_tmds_recalc_rate(struct clk_hw *hw,
 129                                             unsigned long parent_rate)
 130 {
 131         struct sun4i_tmds *tmds = hw_to_tmds(hw);
 132         u32 reg;
 133
 134         reg = readl(tmds->hdmi->base + SUN4I_HDMI_PAD_CTRL1_REG);
 135         if (reg & SUN4I_HDMI_PAD_CTRL1_HALVE_CLK)
 136                 parent_rate /= 2;
 137
 138         reg = readl(tmds->hdmi->base + SUN4I_HDMI_PLL_CTRL_REG);
 139         reg = ((reg >> 4) & 0xf) + tmds->div_offset;
 140         if (!reg)
 141                 reg = 1;
 142
 143         return parent_rate / reg;
 144 }
 145
 146 static int sun4i_tmds_set_rate(struct clk_hw *hw, unsigned long rate,
 147                                unsigned long parent_rate)
 148 {
 149         struct sun4i_tmds *tmds = hw_to_tmds(hw);
 150         bool half;
 151         u32 reg;
 152         u8 div;
 153
 154         sun4i_tmds_calc_divider(rate, parent_rate, tmds->div_offset,
 155                                 &div, &half);
 156
 157         reg = readl(tmds->hdmi->base + SUN4I_HDMI_PAD_CTRL1_REG);
 158         reg &= ~SUN4I_HDMI_PAD_CTRL1_HALVE_CLK;
 159         if (half)
 160                 reg |= SUN4I_HDMI_PAD_CTRL1_HALVE_CLK;
 161         writel(reg, tmds->hdmi->base + SUN4I_HDMI_PAD_CTRL1_REG);
 162
 163         reg = readl(tmds->hdmi->base + SUN4I_HDMI_PLL_CTRL_REG);
 164         reg &= ~SUN4I_HDMI_PLL_CTRL_DIV_MASK;
 165         writel(reg | SUN4I_HDMI_PLL_CTRL_DIV(div - tmds->div_offset),
 166                tmds->hdmi->base + SUN4I_HDMI_PLL_CTRL_REG);
 167
 168         return 0;
 169 }
 170
 171 static u8 sun4i_tmds_get_parent(struct clk_hw *hw)
 172 {
 173         struct sun4i_tmds *tmds = hw_to_tmds(hw);
 174         u32 reg;
 175
 176         reg = readl(tmds->hdmi->base + SUN4I_HDMI_PLL_DBG0_REG);
 177         return ((reg & SUN4I_HDMI_PLL_DBG0_TMDS_PARENT_MASK) >>
 178                 SUN4I_HDMI_PLL_DBG0_TMDS_PARENT_SHIFT);
 179 }
 180
 181 static int sun4i_tmds_set_parent(struct clk_hw *hw, u8 index)
 182 {
 183         struct sun4i_tmds *tmds = hw_to_tmds(hw);
 184         u32 reg;
 185
 186         if (index > 1)
 187                 return -EINVAL;
 188
 189         reg = readl(tmds->hdmi->base + SUN4I_HDMI_PLL_DBG0_REG);
 190         reg &= ~SUN4I_HDMI_PLL_DBG0_TMDS_PARENT_MASK;
 191         writel(reg | SUN4I_HDMI_PLL_DBG0_TMDS_PARENT(index),
 192                tmds->hdmi->base + SUN4I_HDMI_PLL_DBG0_REG);
 193
 194         return 0;
 195 }
 196
 197 static const struct clk_ops sun4i_tmds_ops = {
 198         .determine_rate = sun4i_tmds_determine_rate,
 199         .recalc_rate    = sun4i_tmds_recalc_rate,
 200         .set_rate       = sun4i_tmds_set_rate,
 201
 202         .get_parent     = sun4i_tmds_get_parent,
 203         .set_parent     = sun4i_tmds_set_parent,
 204 };
 205
 206 int sun4i_tmds_create(struct sun4i_hdmi *hdmi)
 207 {
 208         struct clk_init_data init;
 209         struct sun4i_tmds *tmds;
 210         const char *parents[2];
 211
 212         parents[0] = __clk_get_name(hdmi->pll0_clk);
 213         if (!parents[0])
 214                 return -ENODEV;
 215
 216         parents[1] = __clk_get_name(hdmi->pll1_clk);
 217         if (!parents[1])
 218                 return -ENODEV;
 219
 220         tmds = devm_kzalloc(hdmi->dev, sizeof(*tmds), GFP_KERNEL);
 221         if (!tmds)
 222                 return -ENOMEM;
 223
 224         init.name = "hdmi-tmds";
 225         init.ops = &sun4i_tmds_ops;
 226         init.parent_names = parents;
 227         init.num_parents = 2;
 228         init.flags = CLK_SET_RATE_PARENT;
 229
 230         tmds->hdmi = hdmi;
 231         tmds->hw.init = &init;
 232         tmds->div_offset = hdmi->variant->tmds_clk_div_offset;
 233
 234         hdmi->tmds_clk = devm_clk_register(hdmi->dev, &tmds->hw);
 235         if (IS_ERR(hdmi->tmds_clk))
 236                 return PTR_ERR(hdmi->tmds_clk);
 237
 238         return 0;
 239 }