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.h>
  14 #include <linux/clk-provider.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/io.h>
  18 #include <linux/err.h>
  19
  20 /*
  21  * DOC: basic adjustable multiplexer clock that cannot gate
  22  *
  23  * Traits of this clock:
  24  * prepare - clk_prepare only ensures that parents are prepared
  25  * enable - clk_enable only ensures that parents are enabled
  26  * rate - rate is only affected by parent switching.  No clk_set_rate support
  27  * parent - parent is adjustable through clk_set_parent
  28  */
  29
  30 #define to_clk_mux(_hw) container_of(_hw, struct clk_mux, hw)
  31
  32 static u8 clk_mux_get_parent(struct clk_hw *hw)
  33 {
  34         struct clk_mux *mux = to_clk_mux(hw);
  35         int num_parents = __clk_get_num_parents(hw->clk);
  36         u32 val;
  37
  38         /*
  39          * FIXME need a mux-specific flag to determine if val is bitwise or numeric
  40          * e.g. sys_clkin_ck's clksel field is 3 bits wide, but ranges from 0x1
  41          * to 0x7 (index starts at one)
  42          * OTOH, pmd_trace_clk_mux_ck uses a separate bit for each clock, so
  43          * val = 0x4 really means "bit 2, index starts at bit 0"
  44          */
  45         val = readl(mux->reg) >> mux->shift;
  46         val &= mux->mask;
  47
  48         if (mux->table) {
  49                 int i;
  50
  51                 for (i = 0; i < num_parents; i++)
  52                         if (mux->table[i] == val)
  53                                 return i;
  54                 return -EINVAL;
  55         }
  56
  57         if (val && (mux->flags & CLK_MUX_INDEX_BIT))
  58                 val = ffs(val) - 1;
  59
  60         if (val && (mux->flags & CLK_MUX_INDEX_ONE))
  61                 val--;
  62
  63         if (val >= num_parents)
  64                 return -EINVAL;
  65
  66         return val;
  67 }
  68
  69 static int clk_mux_set_parent(struct clk_hw *hw, u8 index)
  70 {
  71         struct clk_mux *mux = to_clk_mux(hw);
  72         u32 val;
  73         unsigned long flags = 0;
  74
  75         if (mux->table)
  76                 index = mux->table[index];
  77
  78         else {
  79                 if (mux->flags & CLK_MUX_INDEX_BIT)
  80                         index = (1 << ffs(index));
  81
  82                 if (mux->flags & CLK_MUX_INDEX_ONE)
  83                         index++;
  84         }
  85
  86         if (mux->lock)
  87                 spin_lock_irqsave(mux->lock, flags);
  88
  89         if (mux->flags & CLK_MUX_HIWORD_MASK) {
  90                 val = mux->mask << (mux->shift + 16);
  91         } else {
  92                 val = readl(mux->reg);
  93                 val &= ~(mux->mask << mux->shift);
  94         }
  95         val |= index << mux->shift;
  96         writel(val, mux->reg);
  97
  98         if (mux->lock)
  99                 spin_unlock_irqrestore(mux->lock, flags);
 100
 101         return 0;
 102 }
 103
 104 const struct clk_ops clk_mux_ops = {
 105         .get_parent = clk_mux_get_parent,
 106         .set_parent = clk_mux_set_parent,
 107 };
 108 EXPORT_SYMBOL_GPL(clk_mux_ops);
 109
 110 struct clk *clk_register_mux_table(struct device *dev, const char *name,
 111                 const char **parent_names, u8 num_parents, unsigned long flags,
 112                 void __iomem *reg, u8 shift, u32 mask,
 113                 u8 clk_mux_flags, u32 *table, spinlock_t *lock)
 114 {
 115         struct clk_mux *mux;
 116         struct clk *clk;
 117         struct clk_init_data init;
 118         u8 width = 0;
 119
 120         if (clk_mux_flags & CLK_MUX_HIWORD_MASK) {
 121                 width = fls(mask) - ffs(mask) + 1;
 122                 if (width + shift > 16) {
 123                         pr_err("mux value exceeds LOWORD field\n");
 124                         return ERR_PTR(-EINVAL);
 125                 }
 126         }
 127
 128         /* allocate the mux */
 129         mux = kzalloc(sizeof(struct clk_mux), GFP_KERNEL);
 130         if (!mux) {
 131                 pr_err("%s: could not allocate mux clk\n", __func__);
 132                 return ERR_PTR(-ENOMEM);
 133         }
 134
 135         init.name = name;
 136         init.ops = &clk_mux_ops;
 137         init.flags = flags | CLK_IS_BASIC;
 138         init.parent_names = parent_names;
 139         init.num_parents = num_parents;
 140
 141         /* struct clk_mux assignments */
 142         mux->reg = reg;
 143         mux->shift = shift;
 144         mux->mask = mask;
 145         mux->flags = clk_mux_flags;
 146         mux->lock = lock;
 147         mux->table = table;
 148         mux->hw.init = &init;
 149
 150         clk = clk_register(dev, &mux->hw);
 151
 152         if (IS_ERR(clk))
 153                 kfree(mux);
 154
 155         return clk;
 156 }
 157
 158 struct clk *clk_register_mux(struct device *dev, const char *name,
 159                 const char **parent_names, u8 num_parents, unsigned long flags,
 160                 void __iomem *reg, u8 shift, u8 width,
 161                 u8 clk_mux_flags, spinlock_t *lock)
 162 {
 163         u32 mask = BIT(width) - 1;
 164
 165         return clk_register_mux_table(dev, name, parent_names, num_parents,
 166                                       flags, reg, shift, mask, clk_mux_flags,
 167                                       NULL, lock);
 168 }