ARM: 6124/1: ep93xx: SPI driver platform support code
[safe/jmp/linux-2.6] / arch / arm / mach-ep93xx / clock.c
index b2eede5..e29bdef 100644 (file)
  * your option) any later version.
  */
 
+#define pr_fmt(fmt) "ep93xx " KBUILD_MODNAME ": " fmt
+
 #include <linux/kernel.h>
 #include <linux/clk.h>
 #include <linux/err.h>
 #include <linux/module.h>
 #include <linux/string.h>
 #include <linux/io.h>
+#include <linux/spinlock.h>
 
-#include <asm/clkdev.h>
-#include <asm/div64.h>
 #include <mach/hardware.h>
 
-
-/*
- * The EP93xx has two external crystal oscillators.  To generate the
- * required high-frequency clocks, the processor uses two phase-locked-
- * loops (PLLs) to multiply the incoming external clock signal to much
- * higher frequencies that are then divided down by programmable dividers
- * to produce the needed clocks.  The PLLs operate independently of one
- * another.
- */
-#define EP93XX_EXT_CLK_RATE    14745600
-#define EP93XX_EXT_RTC_RATE    32768
+#include <asm/clkdev.h>
+#include <asm/div64.h>
 
 
 struct clk {
+       struct clk      *parent;
        unsigned long   rate;
        int             users;
        int             sw_locked;
-       u32             enable_reg;
+       void __iomem    *enable_reg;
        u32             enable_mask;
 
        unsigned long   (*get_rate)(struct clk *clk);
+       int             (*set_rate)(struct clk *clk, unsigned long rate);
 };
 
 
 static unsigned long get_uart_rate(struct clk *clk);
 
+static int set_keytchclk_rate(struct clk *clk, unsigned long rate);
+static int set_div_rate(struct clk *clk, unsigned long rate);
 
+
+static struct clk clk_xtali = {
+       .rate           = EP93XX_EXT_CLK_RATE,
+};
 static struct clk clk_uart1 = {
+       .parent         = &clk_xtali,
        .sw_locked      = 1,
-       .enable_reg     = EP93XX_SYSCON_DEVICE_CONFIG,
-       .enable_mask    = EP93XX_SYSCON_DEVICE_CONFIG_U1EN,
+       .enable_reg     = EP93XX_SYSCON_DEVCFG,
+       .enable_mask    = EP93XX_SYSCON_DEVCFG_U1EN,
        .get_rate       = get_uart_rate,
 };
 static struct clk clk_uart2 = {
+       .parent         = &clk_xtali,
        .sw_locked      = 1,
-       .enable_reg     = EP93XX_SYSCON_DEVICE_CONFIG,
-       .enable_mask    = EP93XX_SYSCON_DEVICE_CONFIG_U2EN,
+       .enable_reg     = EP93XX_SYSCON_DEVCFG,
+       .enable_mask    = EP93XX_SYSCON_DEVCFG_U2EN,
        .get_rate       = get_uart_rate,
 };
 static struct clk clk_uart3 = {
+       .parent         = &clk_xtali,
        .sw_locked      = 1,
-       .enable_reg     = EP93XX_SYSCON_DEVICE_CONFIG,
-       .enable_mask    = EP93XX_SYSCON_DEVICE_CONFIG_U3EN,
+       .enable_reg     = EP93XX_SYSCON_DEVCFG,
+       .enable_mask    = EP93XX_SYSCON_DEVCFG_U3EN,
        .get_rate       = get_uart_rate,
 };
-static struct clk clk_pll1;
-static struct clk clk_f;
-static struct clk clk_h;
-static struct clk clk_p;
-static struct clk clk_pll2;
+static struct clk clk_pll1 = {
+       .parent         = &clk_xtali,
+};
+static struct clk clk_f = {
+       .parent         = &clk_pll1,
+};
+static struct clk clk_h = {
+       .parent         = &clk_pll1,
+};
+static struct clk clk_p = {
+       .parent         = &clk_pll1,
+};
+static struct clk clk_pll2 = {
+       .parent         = &clk_xtali,
+};
 static struct clk clk_usb_host = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = EP93XX_SYSCON_CLOCK_USH_EN,
+       .parent         = &clk_pll2,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_USH_EN,
+};
+static struct clk clk_keypad = {
+       .parent         = &clk_xtali,
+       .sw_locked      = 1,
+       .enable_reg     = EP93XX_SYSCON_KEYTCHCLKDIV,
+       .enable_mask    = EP93XX_SYSCON_KEYTCHCLKDIV_KEN,
+       .set_rate       = set_keytchclk_rate,
+};
+static struct clk clk_spi = {
+       .parent         = &clk_xtali,
+       .rate           = EP93XX_EXT_CLK_RATE,
+};
+static struct clk clk_pwm = {
+       .parent         = &clk_xtali,
+       .rate           = EP93XX_EXT_CLK_RATE,
+};
+
+static struct clk clk_video = {
+       .sw_locked      = 1,
+       .enable_reg     = EP93XX_SYSCON_VIDCLKDIV,
+       .enable_mask    = EP93XX_SYSCON_CLKDIV_ENABLE,
+       .set_rate       = set_div_rate,
 };
 
 /* DMA Clocks */
 static struct clk clk_m2p0 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x00020000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P0,
 };
 static struct clk clk_m2p1 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x00010000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P1,
 };
 static struct clk clk_m2p2 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x00080000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P2,
 };
 static struct clk clk_m2p3 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x00040000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P3,
 };
 static struct clk clk_m2p4 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x00200000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P4,
 };
 static struct clk clk_m2p5 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x00100000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P5,
 };
 static struct clk clk_m2p6 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x00800000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P6,
 };
 static struct clk clk_m2p7 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x00400000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P7,
 };
 static struct clk clk_m2p8 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x02000000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P8,
 };
 static struct clk clk_m2p9 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x01000000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2P9,
 };
 static struct clk clk_m2m0 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x04000000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2M0,
 };
 static struct clk clk_m2m1 = {
-       .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
-       .enable_mask    = 0x08000000,
+       .parent         = &clk_h,
+       .enable_reg     = EP93XX_SYSCON_PWRCNT,
+       .enable_mask    = EP93XX_SYSCON_PWRCNT_DMA_M2M1,
 };
 
 #define INIT_CK(dev,con,ck)                                    \
        { .dev_id = dev, .con_id = con, .clk = ck }
 
 static struct clk_lookup clocks[] = {
-       INIT_CK("apb:uart1", NULL, &clk_uart1),
-       INIT_CK("apb:uart2", NULL, &clk_uart2),
-       INIT_CK("apb:uart3", NULL, &clk_uart3),
-       INIT_CK(NULL, "pll1", &clk_pll1),
-       INIT_CK(NULL, "fclk", &clk_f),
-       INIT_CK(NULL, "hclk", &clk_h),
-       INIT_CK(NULL, "pclk", &clk_p),
-       INIT_CK(NULL, "pll2", &clk_pll2),
-       INIT_CK(NULL, "usb_host", &clk_usb_host),
-       INIT_CK(NULL, "m2p0", &clk_m2p0),
-       INIT_CK(NULL, "m2p1", &clk_m2p1),
-       INIT_CK(NULL, "m2p2", &clk_m2p2),
-       INIT_CK(NULL, "m2p3", &clk_m2p3),
-       INIT_CK(NULL, "m2p4", &clk_m2p4),
-       INIT_CK(NULL, "m2p5", &clk_m2p5),
-       INIT_CK(NULL, "m2p6", &clk_m2p6),
-       INIT_CK(NULL, "m2p7", &clk_m2p7),
-       INIT_CK(NULL, "m2p8", &clk_m2p8),
-       INIT_CK(NULL, "m2p9", &clk_m2p9),
-       INIT_CK(NULL, "m2m0", &clk_m2m0),
-       INIT_CK(NULL, "m2m1", &clk_m2m1),
+       INIT_CK(NULL,                   "xtali",        &clk_xtali),
+       INIT_CK("apb:uart1",            NULL,           &clk_uart1),
+       INIT_CK("apb:uart2",            NULL,           &clk_uart2),
+       INIT_CK("apb:uart3",            NULL,           &clk_uart3),
+       INIT_CK(NULL,                   "pll1",         &clk_pll1),
+       INIT_CK(NULL,                   "fclk",         &clk_f),
+       INIT_CK(NULL,                   "hclk",         &clk_h),
+       INIT_CK(NULL,                   "pclk",         &clk_p),
+       INIT_CK(NULL,                   "pll2",         &clk_pll2),
+       INIT_CK("ep93xx-ohci",          NULL,           &clk_usb_host),
+       INIT_CK("ep93xx-keypad",        NULL,           &clk_keypad),
+       INIT_CK("ep93xx-fb",            NULL,           &clk_video),
+       INIT_CK("ep93xx-spi.0",         NULL,           &clk_spi),
+       INIT_CK(NULL,                   "pwm_clk",      &clk_pwm),
+       INIT_CK(NULL,                   "m2p0",         &clk_m2p0),
+       INIT_CK(NULL,                   "m2p1",         &clk_m2p1),
+       INIT_CK(NULL,                   "m2p2",         &clk_m2p2),
+       INIT_CK(NULL,                   "m2p3",         &clk_m2p3),
+       INIT_CK(NULL,                   "m2p4",         &clk_m2p4),
+       INIT_CK(NULL,                   "m2p5",         &clk_m2p5),
+       INIT_CK(NULL,                   "m2p6",         &clk_m2p6),
+       INIT_CK(NULL,                   "m2p7",         &clk_m2p7),
+       INIT_CK(NULL,                   "m2p8",         &clk_m2p8),
+       INIT_CK(NULL,                   "m2p9",         &clk_m2p9),
+       INIT_CK(NULL,                   "m2m0",         &clk_m2m0),
+       INIT_CK(NULL,                   "m2m1",         &clk_m2m1),
 };
 
+static DEFINE_SPINLOCK(clk_lock);
+
+static void __clk_enable(struct clk *clk)
+{
+       if (!clk->users++) {
+               if (clk->parent)
+                       __clk_enable(clk->parent);
+
+               if (clk->enable_reg) {
+                       u32 v;
+
+                       v = __raw_readl(clk->enable_reg);
+                       v |= clk->enable_mask;
+                       if (clk->sw_locked)
+                               ep93xx_syscon_swlocked_write(v, clk->enable_reg);
+                       else
+                               __raw_writel(v, clk->enable_reg);
+               }
+       }
+}
 
 int clk_enable(struct clk *clk)
 {
-       if (!clk->users++ && clk->enable_reg) {
-               u32 value;
+       unsigned long flags;
 
-               value = __raw_readl(clk->enable_reg);
-               if (clk->sw_locked)
-                       __raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
-               __raw_writel(value | clk->enable_mask, clk->enable_reg);
-       }
+       if (!clk)
+               return -EINVAL;
+
+       spin_lock_irqsave(&clk_lock, flags);
+       __clk_enable(clk);
+       spin_unlock_irqrestore(&clk_lock, flags);
 
        return 0;
 }
 EXPORT_SYMBOL(clk_enable);
 
+static void __clk_disable(struct clk *clk)
+{
+       if (!--clk->users) {
+               if (clk->enable_reg) {
+                       u32 v;
+
+                       v = __raw_readl(clk->enable_reg);
+                       v &= ~clk->enable_mask;
+                       if (clk->sw_locked)
+                               ep93xx_syscon_swlocked_write(v, clk->enable_reg);
+                       else
+                               __raw_writel(v, clk->enable_reg);
+               }
+
+               if (clk->parent)
+                       __clk_disable(clk->parent);
+       }
+}
+
 void clk_disable(struct clk *clk)
 {
-       if (!--clk->users && clk->enable_reg) {
-               u32 value;
+       unsigned long flags;
 
-               value = __raw_readl(clk->enable_reg);
-               if (clk->sw_locked)
-                       __raw_writel(0xaa, EP93XX_SYSCON_SWLOCK);
-               __raw_writel(value & ~clk->enable_mask, clk->enable_reg);
-       }
+       if (!clk)
+               return;
+
+       spin_lock_irqsave(&clk_lock, flags);
+       __clk_disable(clk);
+       spin_unlock_irqrestore(&clk_lock, flags);
 }
 EXPORT_SYMBOL(clk_disable);
 
 static unsigned long get_uart_rate(struct clk *clk)
 {
+       unsigned long rate = clk_get_rate(clk->parent);
        u32 value;
 
-       value = __raw_readl(EP93XX_SYSCON_CLOCK_CONTROL);
-       if (value & EP93XX_SYSCON_CLOCK_UARTBAUD)
-               return EP93XX_EXT_CLK_RATE;
+       value = __raw_readl(EP93XX_SYSCON_PWRCNT);
+       if (value & EP93XX_SYSCON_PWRCNT_UARTBAUD)
+               return rate;
        else
-               return EP93XX_EXT_CLK_RATE / 2;
+               return rate / 2;
 }
 
 unsigned long clk_get_rate(struct clk *clk)
@@ -202,6 +295,121 @@ unsigned long clk_get_rate(struct clk *clk)
 }
 EXPORT_SYMBOL(clk_get_rate);
 
+static int set_keytchclk_rate(struct clk *clk, unsigned long rate)
+{
+       u32 val;
+       u32 div_bit;
+
+       val = __raw_readl(clk->enable_reg);
+
+       /*
+        * The Key Matrix and ADC clocks are configured using the same
+        * System Controller register.  The clock used will be either
+        * 1/4 or 1/16 the external clock rate depending on the
+        * EP93XX_SYSCON_KEYTCHCLKDIV_KDIV/EP93XX_SYSCON_KEYTCHCLKDIV_ADIV
+        * bit being set or cleared.
+        */
+       div_bit = clk->enable_mask >> 15;
+
+       if (rate == EP93XX_KEYTCHCLK_DIV4)
+               val |= div_bit;
+       else if (rate == EP93XX_KEYTCHCLK_DIV16)
+               val &= ~div_bit;
+       else
+               return -EINVAL;
+
+       ep93xx_syscon_swlocked_write(val, clk->enable_reg);
+       clk->rate = rate;
+       return 0;
+}
+
+static int calc_clk_div(struct clk *clk, unsigned long rate,
+                       int *psel, int *esel, int *pdiv, int *div)
+{
+       struct clk *mclk;
+       unsigned long max_rate, actual_rate, mclk_rate, rate_err = -1;
+       int i, found = 0, __div = 0, __pdiv = 0;
+
+       /* Don't exceed the maximum rate */
+       max_rate = max(max(clk_pll1.rate / 4, clk_pll2.rate / 4),
+                      clk_xtali.rate / 4);
+       rate = min(rate, max_rate);
+
+       /*
+        * Try the two pll's and the external clock
+        * Because the valid predividers are 2, 2.5 and 3, we multiply
+        * all the clocks by 2 to avoid floating point math.
+        *
+        * This is based on the algorithm in the ep93xx raster guide:
+        * http://be-a-maverick.com/en/pubs/appNote/AN269REV1.pdf
+        *
+        */
+       for (i = 0; i < 3; i++) {
+               if (i == 0)
+                       mclk = &clk_xtali;
+               else if (i == 1)
+                       mclk = &clk_pll1;
+               else
+                       mclk = &clk_pll2;
+               mclk_rate = mclk->rate * 2;
+
+               /* Try each predivider value */
+               for (__pdiv = 4; __pdiv <= 6; __pdiv++) {
+                       __div = mclk_rate / (rate * __pdiv);
+                       if (__div < 2 || __div > 127)
+                               continue;
+
+                       actual_rate = mclk_rate / (__pdiv * __div);
+
+                       if (!found || abs(actual_rate - rate) < rate_err) {
+                               *pdiv = __pdiv - 3;
+                               *div = __div;
+                               *psel = (i == 2);
+                               *esel = (i != 0);
+                               clk->parent = mclk;
+                               clk->rate = actual_rate;
+                               rate_err = abs(actual_rate - rate);
+                               found = 1;
+                       }
+               }
+       }
+
+       if (!found)
+               return -EINVAL;
+
+       return 0;
+}
+
+static int set_div_rate(struct clk *clk, unsigned long rate)
+{
+       int err, psel = 0, esel = 0, pdiv = 0, div = 0;
+       u32 val;
+
+       err = calc_clk_div(clk, rate, &psel, &esel, &pdiv, &div);
+       if (err)
+               return err;
+
+       /* Clear the esel, psel, pdiv and div bits */
+       val = __raw_readl(clk->enable_reg);
+       val &= ~0x7fff;
+
+       /* Set the new esel, psel, pdiv and div bits for the new clock rate */
+       val |= (esel ? EP93XX_SYSCON_CLKDIV_ESEL : 0) |
+               (psel ? EP93XX_SYSCON_CLKDIV_PSEL : 0) |
+               (pdiv << EP93XX_SYSCON_CLKDIV_PDIV_SHIFT) | div;
+       ep93xx_syscon_swlocked_write(val, clk->enable_reg);
+       return 0;
+}
+
+int clk_set_rate(struct clk *clk, unsigned long rate)
+{
+       if (clk->set_rate)
+               return clk->set_rate(clk, rate);
+
+       return -EINVAL;
+}
+EXPORT_SYMBOL(clk_set_rate);
+
 
 static char fclk_divisors[] = { 1, 2, 4, 8, 16, 1, 1, 1 };
 static char hclk_divisors[] = { 1, 2, 4, 5, 6, 8, 16, 32 };
@@ -215,7 +423,7 @@ static unsigned long calc_pll_rate(u32 config_word)
        unsigned long long rate;
        int i;
 
-       rate = EP93XX_EXT_CLK_RATE;
+       rate = clk_xtali.rate;
        rate *= ((config_word >> 11) & 0x1f) + 1;               /* X1FBD */
        rate *= ((config_word >> 5) & 0x3f) + 1;                /* X2FBD */
        do_div(rate, (config_word & 0x1f) + 1);                 /* X2IPD */
@@ -244,37 +452,47 @@ static void __init ep93xx_dma_clock_init(void)
 static int __init ep93xx_clock_init(void)
 {
        u32 value;
-       int i;
 
-       value = __raw_readl(EP93XX_SYSCON_CLOCK_SET1);
-       if (!(value & 0x00800000)) {                    /* PLL1 bypassed?  */
-               clk_pll1.rate = EP93XX_EXT_CLK_RATE;
-       } else {
+       /* Determine the bootloader configured pll1 rate */
+       value = __raw_readl(EP93XX_SYSCON_CLKSET1);
+       if (!(value & EP93XX_SYSCON_CLKSET1_NBYP1))
+               clk_pll1.rate = clk_xtali.rate;
+       else
                clk_pll1.rate = calc_pll_rate(value);
-       }
+
+       /* Initialize the pll1 derived clocks */
        clk_f.rate = clk_pll1.rate / fclk_divisors[(value >> 25) & 0x7];
        clk_h.rate = clk_pll1.rate / hclk_divisors[(value >> 20) & 0x7];
        clk_p.rate = clk_h.rate / pclk_divisors[(value >> 18) & 0x3];
        ep93xx_dma_clock_init();
 
-       value = __raw_readl(EP93XX_SYSCON_CLOCK_SET2);
-       if (!(value & 0x00080000)) {                    /* PLL2 bypassed?  */
-               clk_pll2.rate = EP93XX_EXT_CLK_RATE;
-       } else if (value & 0x00040000) {                /* PLL2 enabled?  */
+       /* Determine the bootloader configured pll2 rate */
+       value = __raw_readl(EP93XX_SYSCON_CLKSET2);
+       if (!(value & EP93XX_SYSCON_CLKSET2_NBYP2))
+               clk_pll2.rate = clk_xtali.rate;
+       else if (value & EP93XX_SYSCON_CLKSET2_PLL2_EN)
                clk_pll2.rate = calc_pll_rate(value);
-       } else {
+       else
                clk_pll2.rate = 0;
-       }
+
+       /* Initialize the pll2 derived clocks */
        clk_usb_host.rate = clk_pll2.rate / (((value >> 28) & 0xf) + 1);
 
-       printk(KERN_INFO "ep93xx: PLL1 running at %ld MHz, PLL2 at %ld MHz\n",
+       /*
+        * EP93xx SSP clock rate was doubled in version E2. For more information
+        * see:
+        *     http://www.cirrus.com/en/pubs/appNote/AN273REV4.pdf
+        */
+       if (ep93xx_chip_revision() < EP93XX_CHIP_REV_E2)
+               clk_spi.rate /= 2;
+
+       pr_info("PLL1 running at %ld MHz, PLL2 at %ld MHz\n",
                clk_pll1.rate / 1000000, clk_pll2.rate / 1000000);
-       printk(KERN_INFO "ep93xx: FCLK %ld MHz, HCLK %ld MHz, PCLK %ld MHz\n",
+       pr_info("FCLK %ld MHz, HCLK %ld MHz, PCLK %ld MHz\n",
                clk_f.rate / 1000000, clk_h.rate / 1000000,
                clk_p.rate / 1000000);
 
-       for (i = 0; i < ARRAY_SIZE(clocks); i++)
-               clkdev_add(&clocks[i]);
+       clkdev_add_table(clocks, ARRAY_SIZE(clocks));
        return 0;
 }
 arch_initcall(ep93xx_clock_init);