drivers/clk/sunxi-ng/ccu_sdm.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Copyright (C) 2017 Chen-Yu Tsai <wens@csie.org>
   4  */
   5
   6 #include <linux/clk-provider.h>
   7 #include <linux/io.h>
   8 #include <linux/spinlock.h>
   9
  10 #include "ccu_sdm.h"
  11
  12 bool ccu_sdm_helper_is_enabled(struct ccu_common *common,
  13                                struct ccu_sdm_internal *sdm)
  14 {
  15         if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD))
  16                 return false;
  17
  18         if (sdm->enable && !(readl(common->base + common->reg) & sdm->enable))
  19                 return false;
  20
  21         return !!(readl(common->base + sdm->tuning_reg) & sdm->tuning_enable);
  22 }
  23 EXPORT_SYMBOL_NS_GPL(ccu_sdm_helper_is_enabled, SUNXI_CCU);
  24
  25 void ccu_sdm_helper_enable(struct ccu_common *common,
  26                            struct ccu_sdm_internal *sdm,
  27                            unsigned long rate)
  28 {
  29         unsigned long flags;
  30         unsigned int i;
  31         u32 reg;
  32
  33         if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD))
  34                 return;
  35
  36         /* Set the pattern */
  37         for (i = 0; i < sdm->table_size; i++)
  38                 if (sdm->table[i].rate == rate)
  39                         writel(sdm->table[i].pattern,
  40                                common->base + sdm->tuning_reg);
  41
  42         /* Make sure SDM is enabled */
  43         spin_lock_irqsave(common->lock, flags);
  44         reg = readl(common->base + sdm->tuning_reg);
  45         writel(reg | sdm->tuning_enable, common->base + sdm->tuning_reg);
  46         spin_unlock_irqrestore(common->lock, flags);
  47
  48         spin_lock_irqsave(common->lock, flags);
  49         reg = readl(common->base + common->reg);
  50         writel(reg | sdm->enable, common->base + common->reg);
  51         spin_unlock_irqrestore(common->lock, flags);
  52 }
  53 EXPORT_SYMBOL_NS_GPL(ccu_sdm_helper_enable, SUNXI_CCU);
  54
  55 void ccu_sdm_helper_disable(struct ccu_common *common,
  56                             struct ccu_sdm_internal *sdm)
  57 {
  58         unsigned long flags;
  59         u32 reg;
  60
  61         if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD))
  62                 return;
  63
  64         spin_lock_irqsave(common->lock, flags);
  65         reg = readl(common->base + common->reg);
  66         writel(reg & ~sdm->enable, common->base + common->reg);
  67         spin_unlock_irqrestore(common->lock, flags);
  68
  69         spin_lock_irqsave(common->lock, flags);
  70         reg = readl(common->base + sdm->tuning_reg);
  71         writel(reg & ~sdm->tuning_enable, common->base + sdm->tuning_reg);
  72         spin_unlock_irqrestore(common->lock, flags);
  73 }
  74 EXPORT_SYMBOL_NS_GPL(ccu_sdm_helper_disable, SUNXI_CCU);
  75
  76 /*
  77  * Sigma delta modulation provides a way to do fractional-N frequency
  78  * synthesis, in essence allowing the PLL to output any frequency
  79  * within its operational range. On earlier SoCs such as the A10/A20,
  80  * some PLLs support this. On later SoCs, all PLLs support this.
  81  *
  82  * The datasheets do not explain what the "wave top" and "wave bottom"
  83  * parameters mean or do, nor how to calculate the effective output
  84  * frequency. The only examples (and real world usage) are for the audio
  85  * PLL to generate 24.576 and 22.5792 MHz clock rates used by the audio
  86  * peripherals. The author lacks the underlying domain knowledge to
  87  * pursue this.
  88  *
  89  * The goal and function of the following code is to support the two
  90  * clock rates used by the audio subsystem, allowing for proper audio
  91  * playback and capture without any pitch or speed changes.
  92  */
  93 bool ccu_sdm_helper_has_rate(struct ccu_common *common,
  94                              struct ccu_sdm_internal *sdm,
  95                              unsigned long rate)
  96 {
  97         unsigned int i;
  98
  99         if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD))
 100                 return false;
 101
 102         for (i = 0; i < sdm->table_size; i++)
 103                 if (sdm->table[i].rate == rate)
 104                         return true;
 105
 106         return false;
 107 }
 108 EXPORT_SYMBOL_NS_GPL(ccu_sdm_helper_has_rate, SUNXI_CCU);
 109
 110 unsigned long ccu_sdm_helper_read_rate(struct ccu_common *common,
 111                                        struct ccu_sdm_internal *sdm,
 112                                        u32 m, u32 n)
 113 {
 114         unsigned int i;
 115         u32 reg;
 116
 117         pr_debug("%s: Read sigma-delta modulation setting\n",
 118                  clk_hw_get_name(&common->hw));
 119
 120         if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD))
 121                 return 0;
 122
 123         pr_debug("%s: clock is sigma-delta modulated\n",
 124                  clk_hw_get_name(&common->hw));
 125
 126         reg = readl(common->base + sdm->tuning_reg);
 127
 128         pr_debug("%s: pattern reg is 0x%x",
 129                  clk_hw_get_name(&common->hw), reg);
 130
 131         for (i = 0; i < sdm->table_size; i++)
 132                 if (sdm->table[i].pattern == reg &&
 133                     sdm->table[i].m == m && sdm->table[i].n == n)
 134                         return sdm->table[i].rate;
 135
 136         /* We can't calculate the effective clock rate, so just fail. */
 137         return 0;
 138 }
 139 EXPORT_SYMBOL_NS_GPL(ccu_sdm_helper_read_rate, SUNXI_CCU);
 140
 141 int ccu_sdm_helper_get_factors(struct ccu_common *common,
 142                                struct ccu_sdm_internal *sdm,
 143                                unsigned long rate,
 144                                unsigned long *m, unsigned long *n)
 145 {
 146         unsigned int i;
 147
 148         if (!(common->features & CCU_FEATURE_SIGMA_DELTA_MOD))
 149                 return -EINVAL;
 150
 151         for (i = 0; i < sdm->table_size; i++)
 152                 if (sdm->table[i].rate == rate) {
 153                         *m = sdm->table[i].m;
 154                         *n = sdm->table[i].n;
 155                         return 0;
 156                 }
 157
 158         /* nothing found */
 159         return -EINVAL;
 160 }
 161 EXPORT_SYMBOL_NS_GPL(ccu_sdm_helper_get_factors, SUNXI_CCU);