drivers/clk/mmp/clk-apbc.c

   1 /*
   2  * mmp APB clock operation source file
   3  *
   4  * Copyright (C) 2012 Marvell
   5  * Chao Xie <xiechao.mail@gmail.com>
   6  *
   7  * This file is licensed under the terms of the GNU General Public
   8  * License version 2. This program is licensed "as is" without any
   9  * warranty of any kind, whether express or implied.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/io.h>
  14 #include <linux/err.h>
  15 #include <linux/delay.h>
  16 #include <linux/slab.h>
  17
  18 #include "clk.h"
  19
  20 /* Common APB clock register bit definitions */
  21 #define APBC_APBCLK     (1 << 0)  /* APB Bus Clock Enable */
  22 #define APBC_FNCLK      (1 << 1)  /* Functional Clock Enable */
  23 #define APBC_RST        (1 << 2)  /* Reset Generation */
  24 #define APBC_POWER      (1 << 7)  /* Reset Generation */
  25
  26 #define to_clk_apbc(hw) container_of(hw, struct clk_apbc, hw)
  27 struct clk_apbc {
  28         struct clk_hw           hw;
  29         void __iomem            *base;
  30         unsigned int            delay;
  31         unsigned int            flags;
  32         spinlock_t              *lock;
  33 };
  34
  35 static int clk_apbc_prepare(struct clk_hw *hw)
  36 {
  37         struct clk_apbc *apbc = to_clk_apbc(hw);
  38         unsigned int data;
  39         unsigned long flags = 0;
  40
  41         /*
  42          * It may share same register as MUX clock,
  43          * and it will impact FNCLK enable. Spinlock is needed
  44          */
  45         if (apbc->lock)
  46                 spin_lock_irqsave(apbc->lock, flags);
  47
  48         data = readl_relaxed(apbc->base);
  49         if (apbc->flags & APBC_POWER_CTRL)
  50                 data |= APBC_POWER;
  51         data |= APBC_FNCLK;
  52         writel_relaxed(data, apbc->base);
  53
  54         if (apbc->lock)
  55                 spin_unlock_irqrestore(apbc->lock, flags);
  56
  57         udelay(apbc->delay);
  58
  59         if (apbc->lock)
  60                 spin_lock_irqsave(apbc->lock, flags);
  61
  62         data = readl_relaxed(apbc->base);
  63         data |= APBC_APBCLK;
  64         writel_relaxed(data, apbc->base);
  65
  66         if (apbc->lock)
  67                 spin_unlock_irqrestore(apbc->lock, flags);
  68
  69         udelay(apbc->delay);
  70
  71         if (!(apbc->flags & APBC_NO_BUS_CTRL)) {
  72                 if (apbc->lock)
  73                         spin_lock_irqsave(apbc->lock, flags);
  74
  75                 data = readl_relaxed(apbc->base);
  76                 data &= ~APBC_RST;
  77                 writel_relaxed(data, apbc->base);
  78
  79                 if (apbc->lock)
  80                         spin_unlock_irqrestore(apbc->lock, flags);
  81         }
  82
  83         return 0;
  84 }
  85
  86 static void clk_apbc_unprepare(struct clk_hw *hw)
  87 {
  88         struct clk_apbc *apbc = to_clk_apbc(hw);
  89         unsigned long data;
  90         unsigned long flags = 0;
  91
  92         if (apbc->lock)
  93                 spin_lock_irqsave(apbc->lock, flags);
  94
  95         data = readl_relaxed(apbc->base);
  96         if (apbc->flags & APBC_POWER_CTRL)
  97                 data &= ~APBC_POWER;
  98         data &= ~APBC_FNCLK;
  99         writel_relaxed(data, apbc->base);
 100
 101         if (apbc->lock)
 102                 spin_unlock_irqrestore(apbc->lock, flags);
 103
 104         udelay(10);
 105
 106         if (apbc->lock)
 107                 spin_lock_irqsave(apbc->lock, flags);
 108
 109         data = readl_relaxed(apbc->base);
 110         data &= ~APBC_APBCLK;
 111         writel_relaxed(data, apbc->base);
 112
 113         if (apbc->lock)
 114                 spin_unlock_irqrestore(apbc->lock, flags);
 115 }
 116
 117 static const struct clk_ops clk_apbc_ops = {
 118         .prepare = clk_apbc_prepare,
 119         .unprepare = clk_apbc_unprepare,
 120 };
 121
 122 struct clk *mmp_clk_register_apbc(const char *name, const char *parent_name,
 123                 void __iomem *base, unsigned int delay,
 124                 unsigned int apbc_flags, spinlock_t *lock)
 125 {
 126         struct clk_apbc *apbc;
 127         struct clk *clk;
 128         struct clk_init_data init;
 129
 130         apbc = kzalloc(sizeof(*apbc), GFP_KERNEL);
 131         if (!apbc)
 132                 return NULL;
 133
 134         init.name = name;
 135         init.ops = &clk_apbc_ops;
 136         init.flags = CLK_SET_RATE_PARENT;
 137         init.parent_names = (parent_name ? &parent_name : NULL);
 138         init.num_parents = (parent_name ? 1 : 0);
 139
 140         apbc->base = base;
 141         apbc->delay = delay;
 142         apbc->flags = apbc_flags;
 143         apbc->lock = lock;
 144         apbc->hw.init = &init;
 145
 146         clk = clk_register(NULL, &apbc->hw);
 147         if (IS_ERR(clk))
 148                 kfree(apbc);
 149
 150         return clk;
 151 }