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/device.h>
   7 #include <linux/list.h>
   8 #include <linux/errno.h>
   9 #include <linux/err.h>
  10 #include <linux/string.h>
  11 #include <linux/clk.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/mutex.h>
  14
  15 #include <mach/hardware.h>
  16
  17 /*
  18  * Very simple clock implementation - we only have one clock to deal with.
  19  */
  20 struct clk {
  21         unsigned int            enabled;
  22 };
  23
  24 static void clk_gpio27_enable(void)
  25 {
  26         /*
  27          * First, set up the 3.6864MHz clock on GPIO 27 for the SA-1111:
  28          * (SA-1110 Developer's Manual, section 9.1.2.1)
  29          */
  30         GAFR |= GPIO_32_768kHz;
  31         GPDR |= GPIO_32_768kHz;
  32         TUCR = TUCR_3_6864MHz;
  33 }
  34
  35 static void clk_gpio27_disable(void)
  36 {
  37         TUCR = 0;
  38         GPDR &= ~GPIO_32_768kHz;
  39         GAFR &= ~GPIO_32_768kHz;
  40 }
  41
  42 static struct clk clk_gpio27;
  43
  44 static DEFINE_SPINLOCK(clocks_lock);
  45
  46 struct clk *clk_get(struct device *dev, const char *id)
  47 {
  48         const char *devname = dev_name(dev);
  49
  50         return strcmp(devname, "sa1111.0") ? ERR_PTR(-ENOENT) : &clk_gpio27;
  51 }
  52 EXPORT_SYMBOL(clk_get);
  53
  54 void clk_put(struct clk *clk)
  55 {
  56 }
  57 EXPORT_SYMBOL(clk_put);
  58
  59 int clk_enable(struct clk *clk)
  60 {
  61         unsigned long flags;
  62
  63         spin_lock_irqsave(&clocks_lock, flags);
  64         if (clk->enabled++ == 0)
  65                 clk_gpio27_enable();
  66         spin_unlock_irqrestore(&clocks_lock, flags);
  67         return 0;
  68 }
  69 EXPORT_SYMBOL(clk_enable);
  70
  71 void clk_disable(struct clk *clk)
  72 {
  73         unsigned long flags;
  74
  75         WARN_ON(clk->enabled == 0);
  76
  77         spin_lock_irqsave(&clocks_lock, flags);
  78         if (--clk->enabled == 0)
  79                 clk_gpio27_disable();
  80         spin_unlock_irqrestore(&clocks_lock, flags);
  81 }
  82 EXPORT_SYMBOL(clk_disable);
  83
  84 unsigned long clk_get_rate(struct clk *clk)
  85 {
  86         return 3686400;
  87 }
  88 EXPORT_SYMBOL(clk_get_rate);