drivers/clk/at91/clk-master.c

   1 /*
   2  *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  */
  10
  11 #include <linux/clk-provider.h>
  12 #include <linux/clkdev.h>
  13 #include <linux/clk/at91_pmc.h>
  14 #include <linux/of.h>
  15 #include <linux/mfd/syscon.h>
  16 #include <linux/regmap.h>
  17
  18 #include "pmc.h"
  19
  20 #define MASTER_SOURCE_MAX       4
  21
  22 #define MASTER_PRES_MASK        0x7
  23 #define MASTER_PRES_MAX         MASTER_PRES_MASK
  24 #define MASTER_DIV_SHIFT        8
  25 #define MASTER_DIV_MASK         0x3
  26
  27 struct clk_master_characteristics {
  28         struct clk_range output;
  29         u32 divisors[4];
  30         u8 have_div3_pres;
  31 };
  32
  33 struct clk_master_layout {
  34         u32 mask;
  35         u8 pres_shift;
  36 };
  37
  38 #define to_clk_master(hw) container_of(hw, struct clk_master, hw)
  39
  40 struct clk_master {
  41         struct clk_hw hw;
  42         struct regmap *regmap;
  43         const struct clk_master_layout *layout;
  44         const struct clk_master_characteristics *characteristics;
  45 };
  46
  47 static inline bool clk_master_ready(struct regmap *regmap)
  48 {
  49         unsigned int status;
  50
  51         regmap_read(regmap, AT91_PMC_SR, &status);
  52
  53         return status & AT91_PMC_MCKRDY ? 1 : 0;
  54 }
  55
  56 static int clk_master_prepare(struct clk_hw *hw)
  57 {
  58         struct clk_master *master = to_clk_master(hw);
  59
  60         while (!clk_master_ready(master->regmap))
  61                 cpu_relax();
  62
  63         return 0;
  64 }
  65
  66 static int clk_master_is_prepared(struct clk_hw *hw)
  67 {
  68         struct clk_master *master = to_clk_master(hw);
  69
  70         return clk_master_ready(master->regmap);
  71 }
  72
  73 static unsigned long clk_master_recalc_rate(struct clk_hw *hw,
  74                                             unsigned long parent_rate)
  75 {
  76         u8 pres;
  77         u8 div;
  78         unsigned long rate = parent_rate;
  79         struct clk_master *master = to_clk_master(hw);
  80         const struct clk_master_layout *layout = master->layout;
  81         const struct clk_master_characteristics *characteristics =
  82                                                 master->characteristics;
  83         unsigned int mckr;
  84
  85         regmap_read(master->regmap, AT91_PMC_MCKR, &mckr);
  86         mckr &= layout->mask;
  87
  88         pres = (mckr >> layout->pres_shift) & MASTER_PRES_MASK;
  89         div = (mckr >> MASTER_DIV_SHIFT) & MASTER_DIV_MASK;
  90
  91         if (characteristics->have_div3_pres && pres == MASTER_PRES_MAX)
  92                 rate /= 3;
  93         else
  94                 rate >>= pres;
  95
  96         rate /= characteristics->divisors[div];
  97
  98         if (rate < characteristics->output.min)
  99                 pr_warn("master clk is underclocked");
 100         else if (rate > characteristics->output.max)
 101                 pr_warn("master clk is overclocked");
 102
 103         return rate;
 104 }
 105
 106 static u8 clk_master_get_parent(struct clk_hw *hw)
 107 {
 108         struct clk_master *master = to_clk_master(hw);
 109         unsigned int mckr;
 110
 111         regmap_read(master->regmap, AT91_PMC_MCKR, &mckr);
 112
 113         return mckr & AT91_PMC_CSS;
 114 }
 115
 116 static const struct clk_ops master_ops = {
 117         .prepare = clk_master_prepare,
 118         .is_prepared = clk_master_is_prepared,
 119         .recalc_rate = clk_master_recalc_rate,
 120         .get_parent = clk_master_get_parent,
 121 };
 122
 123 static struct clk * __init
 124 at91_clk_register_master(struct regmap *regmap,
 125                 const char *name, int num_parents,
 126                 const char **parent_names,
 127                 const struct clk_master_layout *layout,
 128                 const struct clk_master_characteristics *characteristics)
 129 {
 130         struct clk_master *master;
 131         struct clk *clk = NULL;
 132         struct clk_init_data init;
 133
 134         if (!name || !num_parents || !parent_names)
 135                 return ERR_PTR(-EINVAL);
 136
 137         master = kzalloc(sizeof(*master), GFP_KERNEL);
 138         if (!master)
 139                 return ERR_PTR(-ENOMEM);
 140
 141         init.name = name;
 142         init.ops = &master_ops;
 143         init.parent_names = parent_names;
 144         init.num_parents = num_parents;
 145         init.flags = 0;
 146
 147         master->hw.init = &init;
 148         master->layout = layout;
 149         master->characteristics = characteristics;
 150         master->regmap = regmap;
 151
 152         clk = clk_register(NULL, &master->hw);
 153         if (IS_ERR(clk)) {
 154                 kfree(master);
 155         }
 156
 157         return clk;
 158 }
 159
 160
 161 static const struct clk_master_layout at91rm9200_master_layout = {
 162         .mask = 0x31F,
 163         .pres_shift = 2,
 164 };
 165
 166 static const struct clk_master_layout at91sam9x5_master_layout = {
 167         .mask = 0x373,
 168         .pres_shift = 4,
 169 };
 170
 171
 172 static struct clk_master_characteristics * __init
 173 of_at91_clk_master_get_characteristics(struct device_node *np)
 174 {
 175         struct clk_master_characteristics *characteristics;
 176
 177         characteristics = kzalloc(sizeof(*characteristics), GFP_KERNEL);
 178         if (!characteristics)
 179                 return NULL;
 180
 181         if (of_at91_get_clk_range(np, "atmel,clk-output-range", &characteristics->output))
 182                 goto out_free_characteristics;
 183
 184         of_property_read_u32_array(np, "atmel,clk-divisors",
 185                                    characteristics->divisors, 4);
 186
 187         characteristics->have_div3_pres =
 188                 of_property_read_bool(np, "atmel,master-clk-have-div3-pres");
 189
 190         return characteristics;
 191
 192 out_free_characteristics:
 193         kfree(characteristics);
 194         return NULL;
 195 }
 196
 197 static void __init
 198 of_at91_clk_master_setup(struct device_node *np,
 199                          const struct clk_master_layout *layout)
 200 {
 201         struct clk *clk;
 202         unsigned int num_parents;
 203         const char *parent_names[MASTER_SOURCE_MAX];
 204         const char *name = np->name;
 205         struct clk_master_characteristics *characteristics;
 206         struct regmap *regmap;
 207
 208         num_parents = of_clk_get_parent_count(np);
 209         if (num_parents == 0 || num_parents > MASTER_SOURCE_MAX)
 210                 return;
 211
 212         of_clk_parent_fill(np, parent_names, num_parents);
 213
 214         of_property_read_string(np, "clock-output-names", &name);
 215
 216         characteristics = of_at91_clk_master_get_characteristics(np);
 217         if (!characteristics)
 218                 return;
 219
 220         regmap = syscon_node_to_regmap(of_get_parent(np));
 221         if (IS_ERR(regmap))
 222                 return;
 223
 224         clk = at91_clk_register_master(regmap, name, num_parents,
 225                                        parent_names, layout,
 226                                        characteristics);
 227         if (IS_ERR(clk))
 228                 goto out_free_characteristics;
 229
 230         of_clk_add_provider(np, of_clk_src_simple_get, clk);
 231         return;
 232
 233 out_free_characteristics:
 234         kfree(characteristics);
 235 }
 236
 237 static void __init of_at91rm9200_clk_master_setup(struct device_node *np)
 238 {
 239         of_at91_clk_master_setup(np, &at91rm9200_master_layout);
 240 }
 241 CLK_OF_DECLARE(at91rm9200_clk_master, "atmel,at91rm9200-clk-master",
 242                of_at91rm9200_clk_master_setup);
 243
 244 static void __init of_at91sam9x5_clk_master_setup(struct device_node *np)
 245 {
 246         of_at91_clk_master_setup(np, &at91sam9x5_master_layout);
 247 }
 248 CLK_OF_DECLARE(at91sam9x5_clk_master, "atmel,at91sam9x5-clk-master",
 249                of_at91sam9x5_clk_master_setup);