drivers/clk/at91/clk-system.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 SYSTEM_MAX_ID           31
  21
  22 #define SYSTEM_MAX_NAME_SZ      32
  23
  24 #define to_clk_system(hw) container_of(hw, struct clk_system, hw)
  25 struct clk_system {
  26         struct clk_hw hw;
  27         struct regmap *regmap;
  28         u8 id;
  29 };
  30
  31 static inline int is_pck(int id)
  32 {
  33         return (id >= 8) && (id <= 15);
  34 }
  35
  36 static inline bool clk_system_ready(struct regmap *regmap, int id)
  37 {
  38         unsigned int status;
  39
  40         regmap_read(regmap, AT91_PMC_SR, &status);
  41
  42         return status & (1 << id) ? 1 : 0;
  43 }
  44
  45 static int clk_system_prepare(struct clk_hw *hw)
  46 {
  47         struct clk_system *sys = to_clk_system(hw);
  48
  49         regmap_write(sys->regmap, AT91_PMC_SCER, 1 << sys->id);
  50
  51         if (!is_pck(sys->id))
  52                 return 0;
  53
  54         while (!clk_system_ready(sys->regmap, sys->id))
  55                 cpu_relax();
  56
  57         return 0;
  58 }
  59
  60 static void clk_system_unprepare(struct clk_hw *hw)
  61 {
  62         struct clk_system *sys = to_clk_system(hw);
  63
  64         regmap_write(sys->regmap, AT91_PMC_SCDR, 1 << sys->id);
  65 }
  66
  67 static int clk_system_is_prepared(struct clk_hw *hw)
  68 {
  69         struct clk_system *sys = to_clk_system(hw);
  70         unsigned int status;
  71
  72         regmap_read(sys->regmap, AT91_PMC_SCSR, &status);
  73
  74         if (!(status & (1 << sys->id)))
  75                 return 0;
  76
  77         if (!is_pck(sys->id))
  78                 return 1;
  79
  80         regmap_read(sys->regmap, AT91_PMC_SR, &status);
  81
  82         return status & (1 << sys->id) ? 1 : 0;
  83 }
  84
  85 static const struct clk_ops system_ops = {
  86         .prepare = clk_system_prepare,
  87         .unprepare = clk_system_unprepare,
  88         .is_prepared = clk_system_is_prepared,
  89 };
  90
  91 static struct clk * __init
  92 at91_clk_register_system(struct regmap *regmap, const char *name,
  93                          const char *parent_name, u8 id)
  94 {
  95         struct clk_system *sys;
  96         struct clk *clk = NULL;
  97         struct clk_init_data init;
  98
  99         if (!parent_name || id > SYSTEM_MAX_ID)
 100                 return ERR_PTR(-EINVAL);
 101
 102         sys = kzalloc(sizeof(*sys), GFP_KERNEL);
 103         if (!sys)
 104                 return ERR_PTR(-ENOMEM);
 105
 106         init.name = name;
 107         init.ops = &system_ops;
 108         init.parent_names = &parent_name;
 109         init.num_parents = 1;
 110         init.flags = CLK_SET_RATE_PARENT;
 111
 112         sys->id = id;
 113         sys->hw.init = &init;
 114         sys->regmap = regmap;
 115
 116         clk = clk_register(NULL, &sys->hw);
 117         if (IS_ERR(clk))
 118                 kfree(sys);
 119
 120         return clk;
 121 }
 122
 123 static void __init of_at91rm9200_clk_sys_setup(struct device_node *np)
 124 {
 125         int num;
 126         u32 id;
 127         struct clk *clk;
 128         const char *name;
 129         struct device_node *sysclknp;
 130         const char *parent_name;
 131         struct regmap *regmap;
 132
 133         num = of_get_child_count(np);
 134         if (num > (SYSTEM_MAX_ID + 1))
 135                 return;
 136
 137         regmap = syscon_node_to_regmap(of_get_parent(np));
 138         if (IS_ERR(regmap))
 139                 return;
 140
 141         for_each_child_of_node(np, sysclknp) {
 142                 if (of_property_read_u32(sysclknp, "reg", &id))
 143                         continue;
 144
 145                 if (of_property_read_string(np, "clock-output-names", &name))
 146                         name = sysclknp->name;
 147
 148                 parent_name = of_clk_get_parent_name(sysclknp, 0);
 149
 150                 clk = at91_clk_register_system(regmap, name, parent_name, id);
 151                 if (IS_ERR(clk))
 152                         continue;
 153
 154                 of_clk_add_provider(sysclknp, of_clk_src_simple_get, clk);
 155         }
 156 }
 157 CLK_OF_DECLARE(at91rm9200_clk_sys, "atmel,at91rm9200-clk-system",
 158                of_at91rm9200_clk_sys_setup);