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/of_address.h>
  16 #include <linux/io.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 at91_pmc *pmc;
  28         u8 id;
  29 };
  30
  31 static int clk_system_enable(struct clk_hw *hw)
  32 {
  33         struct clk_system *sys = to_clk_system(hw);
  34         struct at91_pmc *pmc = sys->pmc;
  35
  36         pmc_write(pmc, AT91_PMC_SCER, 1 << sys->id);
  37         return 0;
  38 }
  39
  40 static void clk_system_disable(struct clk_hw *hw)
  41 {
  42         struct clk_system *sys = to_clk_system(hw);
  43         struct at91_pmc *pmc = sys->pmc;
  44
  45         pmc_write(pmc, AT91_PMC_SCDR, 1 << sys->id);
  46 }
  47
  48 static int clk_system_is_enabled(struct clk_hw *hw)
  49 {
  50         struct clk_system *sys = to_clk_system(hw);
  51         struct at91_pmc *pmc = sys->pmc;
  52
  53         return !!(pmc_read(pmc, AT91_PMC_SCSR) & (1 << sys->id));
  54 }
  55
  56 static const struct clk_ops system_ops = {
  57         .enable = clk_system_enable,
  58         .disable = clk_system_disable,
  59         .is_enabled = clk_system_is_enabled,
  60 };
  61
  62 static struct clk * __init
  63 at91_clk_register_system(struct at91_pmc *pmc, const char *name,
  64                          const char *parent_name, u8 id)
  65 {
  66         struct clk_system *sys;
  67         struct clk *clk = NULL;
  68         struct clk_init_data init;
  69
  70         if (!parent_name || id > SYSTEM_MAX_ID)
  71                 return ERR_PTR(-EINVAL);
  72
  73         sys = kzalloc(sizeof(*sys), GFP_KERNEL);
  74         if (!sys)
  75                 return ERR_PTR(-ENOMEM);
  76
  77         init.name = name;
  78         init.ops = &system_ops;
  79         init.parent_names = &parent_name;
  80         init.num_parents = 1;
  81         /*
  82          * CLK_IGNORE_UNUSED is used to avoid ddrck switch off.
  83          * TODO : we should implement a driver supporting at91 ddr controller
  84          * (see drivers/memory) which would request and enable the ddrck clock.
  85          * When this is done we will be able to remove CLK_IGNORE_UNUSED flag.
  86          */
  87         init.flags = CLK_IGNORE_UNUSED;
  88
  89         sys->id = id;
  90         sys->hw.init = &init;
  91         sys->pmc = pmc;
  92
  93         clk = clk_register(NULL, &sys->hw);
  94         if (IS_ERR(clk))
  95                 kfree(sys);
  96
  97         return clk;
  98 }
  99
 100 static void __init
 101 of_at91_clk_sys_setup(struct device_node *np, struct at91_pmc *pmc)
 102 {
 103         int num;
 104         u32 id;
 105         struct clk *clk;
 106         const char *name;
 107         struct device_node *sysclknp;
 108         const char *parent_name;
 109
 110         num = of_get_child_count(np);
 111         if (num > (SYSTEM_MAX_ID + 1))
 112                 return;
 113
 114         for_each_child_of_node(np, sysclknp) {
 115                 if (of_property_read_u32(sysclknp, "reg", &id))
 116                         continue;
 117
 118                 if (of_property_read_string(np, "clock-output-names", &name))
 119                         name = sysclknp->name;
 120
 121                 parent_name = of_clk_get_parent_name(sysclknp, 0);
 122
 123                 clk = at91_clk_register_system(pmc, name, parent_name, id);
 124                 if (IS_ERR(clk))
 125                         continue;
 126
 127                 of_clk_add_provider(sysclknp, of_clk_src_simple_get, clk);
 128         }
 129 }
 130
 131 void __init of_at91rm9200_clk_sys_setup(struct device_node *np,
 132                                         struct at91_pmc *pmc)
 133 {
 134         of_at91_clk_sys_setup(np, pmc);
 135 }