arch/arm/mach-sa1100/clock.c

   1 /*
   2  *  linux/arch/arm/mach-sa1100/clock.c
   3  */
   4 #include <linux/module.h>
   5 #include <linux/kernel.h>
   6 #include <linux/list.h>
   7 #include <linux/errno.h>
   8 #include <linux/err.h>
   9 #include <linux/string.h>
  10 #include <linux/clk.h>
  11 #include <linux/spinlock.h>
  12
  13 #include <asm/hardware.h>
  14 #include <asm/semaphore.h>
  15
  16 struct clk {
  17         struct list_head        node;
  18         unsigned long           rate;
  19         struct module           *owner;
  20         const char              *name;
  21         unsigned int            enabled;
  22         void                    (*enable)(void);
  23         void                    (*disable)(void);
  24 };
  25
  26 static LIST_HEAD(clocks);
  27 static DECLARE_MUTEX(clocks_sem);
  28 static DEFINE_SPINLOCK(clocks_lock);
  29
  30 struct clk *clk_get(struct device *dev, const char *id)
  31 {
  32         struct clk *p, *clk = ERR_PTR(-ENOENT);
  33
  34         down(&clocks_sem);
  35         list_for_each_entry(p, &clocks, node) {
  36                 if (strcmp(id, p->name) == 0 && try_module_get(p->owner)) {
  37                         clk = p;
  38                         break;
  39                 }
  40         }
  41         up(&clocks_sem);
  42
  43         return clk;
  44 }
  45 EXPORT_SYMBOL(clk_get);
  46
  47 void clk_put(struct clk *clk)
  48 {
  49         module_put(clk->owner);
  50 }
  51 EXPORT_SYMBOL(clk_put);
  52
  53 int clk_enable(struct clk *clk)
  54 {
  55         unsigned long flags;
  56
  57         spin_lock_irqsave(&clocks_lock, flags);
  58         if (clk->enabled++ == 0)
  59                 clk->enable();
  60         spin_unlock_irqrestore(&clocks_lock, flags);
  61         return 0;
  62 }
  63 EXPORT_SYMBOL(clk_enable);
  64
  65 void clk_disable(struct clk *clk)
  66 {
  67         unsigned long flags;
  68
  69         WARN_ON(clk->enabled == 0);
  70
  71         spin_lock_irqsave(&clocks_lock, flags);
  72         if (--clk->enabled == 0)
  73                 clk->disable();
  74         spin_unlock_irqrestore(&clocks_lock, flags);
  75 }
  76 EXPORT_SYMBOL(clk_disable);
  77
  78 unsigned long clk_get_rate(struct clk *clk)
  79 {
  80         return clk->rate;
  81 }
  82 EXPORT_SYMBOL(clk_get_rate);
  83
  84
  85 static void clk_gpio27_enable(void)
  86 {
  87         /*
  88          * First, set up the 3.6864MHz clock on GPIO 27 for the SA-1111:
  89          * (SA-1110 Developer's Manual, section 9.1.2.1)
  90          */
  91         GAFR |= GPIO_32_768kHz;
  92         GPDR |= GPIO_32_768kHz;
  93         TUCR = TUCR_3_6864MHz;
  94 }
  95
  96 static void clk_gpio27_disable(void)
  97 {
  98         TUCR = 0;
  99         GPDR &= ~GPIO_32_768kHz;
 100         GAFR &= ~GPIO_32_768kHz;
 101 }
 102
 103 static struct clk clk_gpio27 = {
 104         .name           = "GPIO27_CLK",
 105         .rate           = 3686400,
 106         .enable         = clk_gpio27_enable,
 107         .disable        = clk_gpio27_disable,
 108 };
 109
 110 int clk_register(struct clk *clk)
 111 {
 112         down(&clocks_sem);
 113         list_add(&clk->node, &clocks);
 114         up(&clocks_sem);
 115         return 0;
 116 }
 117 EXPORT_SYMBOL(clk_register);
 118
 119 void clk_unregister(struct clk *clk)
 120 {
 121         down(&clocks_sem);
 122         list_del(&clk->node);
 123         up(&clocks_sem);
 124 }
 125 EXPORT_SYMBOL(clk_unregister);
 126
 127 static int __init clk_init(void)
 128 {
 129         clk_register(&clk_gpio27);
 130         return 0;
 131 }
 132 arch_initcall(clk_init);