drivers/clk/sunxi-ng/ccu_nkm.c

   1 /*
   2  * Copyright (C) 2016 Maxime Ripard
   3  * Maxime Ripard <maxime.ripard@free-electrons.com>
   4  *
   5  * This program is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU General Public License as
   7  * published by the Free Software Foundation; either version 2 of
   8  * the License, or (at your option) any later version.
   9  */
  10
  11 #include <linux/clk-provider.h>
  12 #include <linux/rational.h>
  13
  14 #include "ccu_gate.h"
  15 #include "ccu_nkm.h"
  16
  17 struct _ccu_nkm {
  18         unsigned long   n, max_n;
  19         unsigned long   k, max_k;
  20         unsigned long   m, max_m;
  21 };
  22
  23 static void ccu_nkm_find_best(unsigned long parent, unsigned long rate,
  24                               struct _ccu_nkm *nkm)
  25 {
  26         unsigned long best_rate = 0;
  27         unsigned long best_n = 0, best_k = 0, best_m = 0;
  28         unsigned long _n, _k, _m;
  29
  30         for (_k = 1; _k <= nkm->max_k; _k++) {
  31                 unsigned long tmp_rate;
  32
  33                 rational_best_approximation(rate / _k, parent,
  34                                             nkm->max_n, nkm->max_m, &_n, &_m);
  35
  36                 tmp_rate = parent * _n * _k / _m;
  37
  38                 if (tmp_rate > rate)
  39                         continue;
  40
  41                 if ((rate - tmp_rate) < (rate - best_rate)) {
  42                         best_rate = tmp_rate;
  43                         best_n = _n;
  44                         best_k = _k;
  45                         best_m = _m;
  46                 }
  47         }
  48
  49         nkm->n = best_n;
  50         nkm->k = best_k;
  51         nkm->m = best_m;
  52 }
  53
  54 static void ccu_nkm_disable(struct clk_hw *hw)
  55 {
  56         struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
  57
  58         return ccu_gate_helper_disable(&nkm->common, nkm->enable);
  59 }
  60
  61 static int ccu_nkm_enable(struct clk_hw *hw)
  62 {
  63         struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
  64
  65         return ccu_gate_helper_enable(&nkm->common, nkm->enable);
  66 }
  67
  68 static int ccu_nkm_is_enabled(struct clk_hw *hw)
  69 {
  70         struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
  71
  72         return ccu_gate_helper_is_enabled(&nkm->common, nkm->enable);
  73 }
  74
  75 static unsigned long ccu_nkm_recalc_rate(struct clk_hw *hw,
  76                                         unsigned long parent_rate)
  77 {
  78         struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
  79         unsigned long n, m, k;
  80         u32 reg;
  81
  82         reg = readl(nkm->common.base + nkm->common.reg);
  83
  84         n = reg >> nkm->n.shift;
  85         n &= (1 << nkm->n.width) - 1;
  86
  87         k = reg >> nkm->k.shift;
  88         k &= (1 << nkm->k.width) - 1;
  89
  90         m = reg >> nkm->m.shift;
  91         m &= (1 << nkm->m.width) - 1;
  92
  93         return parent_rate * (n + 1) * (k + 1) / (m + 1);
  94 }
  95
  96 static unsigned long ccu_nkm_round_rate(struct ccu_mux_internal *mux,
  97                                         unsigned long parent_rate,
  98                                         unsigned long rate,
  99                                         void *data)
 100 {
 101         struct ccu_nkm *nkm = data;
 102         struct _ccu_nkm _nkm;
 103
 104         _nkm.max_n = 1 << nkm->n.width;
 105         _nkm.max_k = 1 << nkm->k.width;
 106         _nkm.max_m = nkm->m.max ?: 1 << nkm->m.width;
 107
 108         ccu_nkm_find_best(parent_rate, rate, &_nkm);
 109
 110         return parent_rate * _nkm.n * _nkm.k / _nkm.m;
 111 }
 112
 113 static int ccu_nkm_determine_rate(struct clk_hw *hw,
 114                                   struct clk_rate_request *req)
 115 {
 116         struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
 117
 118         return ccu_mux_helper_determine_rate(&nkm->common, &nkm->mux,
 119                                              req, ccu_nkm_round_rate, nkm);
 120 }
 121
 122 static int ccu_nkm_set_rate(struct clk_hw *hw, unsigned long rate,
 123                            unsigned long parent_rate)
 124 {
 125         struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
 126         struct _ccu_nkm _nkm;
 127         unsigned long flags;
 128         u32 reg;
 129
 130         _nkm.max_n = 1 << nkm->n.width;
 131         _nkm.max_k = 1 << nkm->k.width;
 132         _nkm.max_m = nkm->m.max ?: 1 << nkm->m.width;
 133
 134         ccu_nkm_find_best(parent_rate, rate, &_nkm);
 135
 136         spin_lock_irqsave(nkm->common.lock, flags);
 137
 138         reg = readl(nkm->common.base + nkm->common.reg);
 139         reg &= ~GENMASK(nkm->n.width + nkm->n.shift - 1, nkm->n.shift);
 140         reg &= ~GENMASK(nkm->k.width + nkm->k.shift - 1, nkm->k.shift);
 141         reg &= ~GENMASK(nkm->m.width + nkm->m.shift - 1, nkm->m.shift);
 142
 143         reg |= (_nkm.n - 1) << nkm->n.shift;
 144         reg |= (_nkm.k - 1) << nkm->k.shift;
 145         reg |= (_nkm.m - 1) << nkm->m.shift;
 146
 147         writel(reg, nkm->common.base + nkm->common.reg);
 148
 149         spin_unlock_irqrestore(nkm->common.lock, flags);
 150
 151         ccu_helper_wait_for_lock(&nkm->common, nkm->lock);
 152
 153         return 0;
 154 }
 155
 156 static u8 ccu_nkm_get_parent(struct clk_hw *hw)
 157 {
 158         struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
 159
 160         return ccu_mux_helper_get_parent(&nkm->common, &nkm->mux);
 161 }
 162
 163 static int ccu_nkm_set_parent(struct clk_hw *hw, u8 index)
 164 {
 165         struct ccu_nkm *nkm = hw_to_ccu_nkm(hw);
 166
 167         return ccu_mux_helper_set_parent(&nkm->common, &nkm->mux, index);
 168 }
 169
 170 const struct clk_ops ccu_nkm_ops = {
 171         .disable        = ccu_nkm_disable,
 172         .enable         = ccu_nkm_enable,
 173         .is_enabled     = ccu_nkm_is_enabled,
 174
 175         .get_parent     = ccu_nkm_get_parent,
 176         .set_parent     = ccu_nkm_set_parent,
 177
 178         .determine_rate = ccu_nkm_determine_rate,
 179         .recalc_rate    = ccu_nkm_recalc_rate,
 180         .set_rate       = ccu_nkm_set_rate,
 181 };