drivers/clk/imx/clk-gate2.c

   1 /*
   2  * Copyright (C) 2010-2011 Canonical Ltd <jeremy.kerr@canonical.com>
   3  * Copyright (C) 2011-2012 Mike Turquette, Linaro Ltd <mturquette@linaro.org>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Gated clock implementation
  10  */
  11
  12 #include <linux/clk-provider.h>
  13 #include <linux/module.h>
  14 #include <linux/slab.h>
  15 #include <linux/io.h>
  16 #include <linux/err.h>
  17 #include <linux/string.h>
  18 #include "clk.h"
  19
  20 /**
  21  * DOC: basic gatable clock which can gate and ungate it's ouput
  22  *
  23  * Traits of this clock:
  24  * prepare - clk_(un)prepare only ensures parent is (un)prepared
  25  * enable - clk_enable and clk_disable are functional & control gating
  26  * rate - inherits rate from parent.  No clk_set_rate support
  27  * parent - fixed parent.  No clk_set_parent support
  28  */
  29
  30 struct clk_gate2 {
  31         struct clk_hw hw;
  32         void __iomem    *reg;
  33         u8              bit_idx;
  34         u8              cgr_val;
  35         u8              flags;
  36         spinlock_t      *lock;
  37         unsigned int    *share_count;
  38 };
  39
  40 #define to_clk_gate2(_hw) container_of(_hw, struct clk_gate2, hw)
  41
  42 static int clk_gate2_enable(struct clk_hw *hw)
  43 {
  44         struct clk_gate2 *gate = to_clk_gate2(hw);
  45         u32 reg;
  46         unsigned long flags = 0;
  47
  48         spin_lock_irqsave(gate->lock, flags);
  49
  50         if (gate->share_count && (*gate->share_count)++ > 0)
  51                 goto out;
  52
  53         reg = readl(gate->reg);
  54         reg &= ~(3 << gate->bit_idx);
  55         reg |= gate->cgr_val << gate->bit_idx;
  56         writel(reg, gate->reg);
  57
  58 out:
  59         spin_unlock_irqrestore(gate->lock, flags);
  60
  61         return 0;
  62 }
  63
  64 static void clk_gate2_disable(struct clk_hw *hw)
  65 {
  66         struct clk_gate2 *gate = to_clk_gate2(hw);
  67         u32 reg;
  68         unsigned long flags = 0;
  69
  70         spin_lock_irqsave(gate->lock, flags);
  71
  72         if (gate->share_count) {
  73                 if (WARN_ON(*gate->share_count == 0))
  74                         goto out;
  75                 else if (--(*gate->share_count) > 0)
  76                         goto out;
  77         }
  78
  79         reg = readl(gate->reg);
  80         reg &= ~(3 << gate->bit_idx);
  81         writel(reg, gate->reg);
  82
  83 out:
  84         spin_unlock_irqrestore(gate->lock, flags);
  85 }
  86
  87 static int clk_gate2_reg_is_enabled(void __iomem *reg, u8 bit_idx)
  88 {
  89         u32 val = readl(reg);
  90
  91         if (((val >> bit_idx) & 1) == 1)
  92                 return 1;
  93
  94         return 0;
  95 }
  96
  97 static int clk_gate2_is_enabled(struct clk_hw *hw)
  98 {
  99         struct clk_gate2 *gate = to_clk_gate2(hw);
 100
 101         return clk_gate2_reg_is_enabled(gate->reg, gate->bit_idx);
 102 }
 103
 104 static void clk_gate2_disable_unused(struct clk_hw *hw)
 105 {
 106         struct clk_gate2 *gate = to_clk_gate2(hw);
 107         unsigned long flags = 0;
 108         u32 reg;
 109
 110         spin_lock_irqsave(gate->lock, flags);
 111
 112         if (!gate->share_count || *gate->share_count == 0) {
 113                 reg = readl(gate->reg);
 114                 reg &= ~(3 << gate->bit_idx);
 115                 writel(reg, gate->reg);
 116         }
 117
 118         spin_unlock_irqrestore(gate->lock, flags);
 119 }
 120
 121 static struct clk_ops clk_gate2_ops = {
 122         .enable = clk_gate2_enable,
 123         .disable = clk_gate2_disable,
 124         .disable_unused = clk_gate2_disable_unused,
 125         .is_enabled = clk_gate2_is_enabled,
 126 };
 127
 128 struct clk *clk_register_gate2(struct device *dev, const char *name,
 129                 const char *parent_name, unsigned long flags,
 130                 void __iomem *reg, u8 bit_idx, u8 cgr_val,
 131                 u8 clk_gate2_flags, spinlock_t *lock,
 132                 unsigned int *share_count)
 133 {
 134         struct clk_gate2 *gate;
 135         struct clk *clk;
 136         struct clk_init_data init;
 137
 138         gate = kzalloc(sizeof(struct clk_gate2), GFP_KERNEL);
 139         if (!gate)
 140                 return ERR_PTR(-ENOMEM);
 141
 142         /* struct clk_gate2 assignments */
 143         gate->reg = reg;
 144         gate->bit_idx = bit_idx;
 145         gate->cgr_val = cgr_val;
 146         gate->flags = clk_gate2_flags;
 147         gate->lock = lock;
 148         gate->share_count = share_count;
 149
 150         init.name = name;
 151         init.ops = &clk_gate2_ops;
 152         init.flags = flags;
 153         init.parent_names = parent_name ? &parent_name : NULL;
 154         init.num_parents = parent_name ? 1 : 0;
 155
 156         gate->hw.init = &init;
 157
 158         clk = clk_register(dev, &gate->hw);
 159         if (IS_ERR(clk))
 160                 kfree(gate);
 161
 162         return clk;
 163 }