drivers/clk/clk-mux.c

   1 /*
   2  * Copyright (C) 2011 Sascha Hauer, Pengutronix <s.hauer@pengutronix.de>
   3  * Copyright (C) 2011 Richard Zhao, Linaro <richard.zhao@linaro.org>
   4  * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  * Simple multiplexer clock implementation
  11  */
  12
  13 #include <linux/clk-provider.h>
  14 #include <linux/module.h>
  15 #include <linux/slab.h>
  16 #include <linux/io.h>
  17 #include <linux/err.h>
  18
  19 /*
  20  * DOC: basic adjustable multiplexer clock that cannot gate
  21  *
  22  * Traits of this clock:
  23  * prepare - clk_prepare only ensures that parents are prepared
  24  * enable - clk_enable only ensures that parents are enabled
  25  * rate - rate is only affected by parent switching.  No clk_set_rate support
  26  * parent - parent is adjustable through clk_set_parent
  27  */
  28
  29 #define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)
  30
  31 static u8 clk_mux_get_parent(struct clk_hw *hw)
  32 {
  33         struct clk_mux *mux = to_clk_mux(hw);
  34         int num_parents = clk_hw_get_num_parents(hw);
  35         u32 val;
  36
  37         /*
  38          * FIXME need a mux-specific flag to determine if val is bitwise or numeric
  39          * e.g. sys_clkin_ck's clksel field is 3 bits wide, but ranges from 0x1
  40          * to 0x7 (index starts at one)
  41          * OTOH, pmd_trace_clk_mux_ck uses a separate bit for each clock, so
  42          * val = 0x4 really means "bit 2, index starts at bit 0"
  43          */
  44         val = clk_readl(mux->reg) >> mux->shift;
  45         val &= mux->mask;
  46
  47         if (mux->table) {
  48                 int i;
  49
  50                 for (i = 0; i < num_parents; i++)
  51                         if (mux->table[i] == val)
  52                                 return i;
  53                 return -EINVAL;
  54         }
  55
  56         if (val && (mux->flags & CLK_MUX_INDEX_BIT))
  57                 val = ffs(val) - 1;
  58
  59         if (val && (mux->flags & CLK_MUX_INDEX_ONE))
  60                 val--;
  61
  62         if (val >= num_parents)
  63                 return -EINVAL;
  64
  65         return val;
  66 }
  67
  68 static int clk_mux_set_parent(struct clk_hw *hw, u8 index)
  69 {
  70         struct clk_mux *mux = to_clk_mux(hw);
  71         u32 val;
  72         unsigned long flags = 0;
  73
  74         if (mux->table)
  75                 index = mux->table[index];
  76
  77         else {
  78                 if (mux->flags & CLK_MUX_INDEX_BIT)
  79                         index = 1 << index;
  80
  81                 if (mux->flags & CLK_MUX_INDEX_ONE)
  82                         index++;
  83         }
  84
  85         if (mux->lock)
  86                 spin_lock_irqsave(mux->lock, flags);
  87         else
  88                 __acquire(mux->lock);
  89
  90         if (mux->flags & CLK_MUX_HIWORD_MASK) {
  91                 val = mux->mask << (mux->shift + 16);
  92         } else {
  93                 val = clk_readl(mux->reg);
  94                 val &= ~(mux->mask << mux->shift);
  95         }
  96         val |= index << mux->shift;
  97         clk_writel(val, mux->reg);
  98
  99         if (mux->lock)
 100                 spin_unlock_irqrestore(mux->lock, flags);
 101         else
 102                 __release(mux->lock);
 103
 104         return 0;
 105 }
 106
 107 const struct clk_ops clk_mux_ops = {
 108         .get_parent = clk_mux_get_parent,
 109         .set_parent = clk_mux_set_parent,
 110         .determine_rate = __clk_mux_determine_rate,
 111 };
 112 EXPORT_SYMBOL_GPL(clk_mux_ops);
 113
 114 const struct clk_ops clk_mux_ro_ops = {
 115         .get_parent = clk_mux_get_parent,
 116 };
 117 EXPORT_SYMBOL_GPL(clk_mux_ro_ops);
 118
 119 struct clk *clk_register_mux_table(struct device *dev, const char *name,
 120                 const char * const *parent_names, u8 num_parents,
 121                 unsigned long flags,
 122                 void __iomem *reg, u8 shift, u32 mask,
 123                 u8 clk_mux_flags, u32 *table, spinlock_t *lock)
 124 {
 125         struct clk_mux *mux;
 126         struct clk *clk;
 127         struct clk_init_data init;
 128         u8 width = 0;
 129
 130         if (clk_mux_flags & CLK_MUX_HIWORD_MASK) {
 131                 width = fls(mask) - ffs(mask) + 1;
 132                 if (width + shift > 16) {
 133                         pr_err("mux value exceeds LOWORD field\n");
 134                         return ERR_PTR(-EINVAL);
 135                 }
 136         }
 137
 138         /* allocate the mux */
 139         mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
 140         if (!mux) {
 141                 pr_err("%s: could not allocate mux clk\n", __func__);
 142                 return ERR_PTR(-ENOMEM);
 143         }
 144
 145         init.name = name;
 146         if (clk_mux_flags & CLK_MUX_READ_ONLY)
 147                 init.ops = &clk_mux_ro_ops;
 148         else
 149                 init.ops = &clk_mux_ops;
 150         init.flags = flags | CLK_IS_BASIC;
 151         init.parent_names = parent_names;
 152         init.num_parents = num_parents;
 153
 154         /* struct clk_mux assignments */
 155         mux->reg = reg;
 156         mux->shift = shift;
 157         mux->mask = mask;
 158         mux->flags = clk_mux_flags;
 159         mux->lock = lock;
 160         mux->table = table;
 161         mux->hw.init = &init;
 162
 163         clk = clk_register(dev, &mux->hw);
 164
 165         if (IS_ERR(clk))
 166                 kfree(mux);
 167
 168         return clk;
 169 }
 170 EXPORT_SYMBOL_GPL(clk_register_mux_table);
 171
 172 struct clk *clk_register_mux(struct device *dev, const char *name,
 173                 const char * const *parent_names, u8 num_parents,
 174                 unsigned long flags,
 175                 void __iomem *reg, u8 shift, u8 width,
 176                 u8 clk_mux_flags, spinlock_t *lock)
 177 {
 178         u32 mask = BIT(width) - 1;
 179
 180         return clk_register_mux_table(dev, name, parent_names, num_parents,
 181                                       flags, reg, shift, mask, clk_mux_flags,
 182                                       NULL, lock);
 183 }
 184 EXPORT_SYMBOL_GPL(clk_register_mux);
 185
 186 void clk_unregister_mux(struct clk *clk)
 187 {
 188         struct clk_mux *mux;
 189         struct clk_hw *hw;
 190
 191         hw = __clk_get_hw(clk);
 192         if (!hw)
 193                 return;
 194
 195         mux = to_clk_mux(hw);
 196
 197         clk_unregister(clk);
 198         kfree(mux);
 199 }
 200 EXPORT_SYMBOL_GPL(clk_unregister_mux);