ARM: OMAP2: Add common clock framework for 24xx and 34xx

This patch adds a common clock framework for 24xx and 34xx.
Note that this patch does not add it to Makefile until in
next patch. Some functions are modified from earlier 24xx
clock framework code.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/mach-omap2/clock.c

+/*
+ *  linux/arch/arm/mach-omap2/clock.c
+ *
+ *  Copyright (C) 2005 Texas Instruments Inc.
+ *  Richard Woodruff <r-woodruff2@ti.com>
+ *  Created for OMAP2.
+ *
+ *  Cleaned up and modified to use omap shared clock framework by
+ *  Tony Lindgren <tony@atomide.com>
+ *
+ *  Copyright (C) 2007 Texas Instruments, Inc.
+ *  Copyright (C) 2007 Nokia Corporation
+ *  Paul Walmsley
+ *
+ *  Based on omap1 clock.c, Copyright (C) 2004 - 2005 Nokia corporation
+ *  Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#undef DEBUG
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/list.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/clk.h>
+#include <asm/bitops.h>
+
+#include <asm/io.h>
+
+#include <asm/arch/clock.h>
+#include <asm/arch/sram.h>
+#include <asm/arch/cpu.h>
+#include <asm/div64.h>
+
+#include "memory.h"
+#include "sdrc.h"
+#include "clock.h"
+#include "prm.h"
+#include "prm-regbits-24xx.h"
+#include "cm.h"
+#include "cm-regbits-24xx.h"
+#include "cm-regbits-34xx.h"
+
+#define MAX_CLOCK_ENABLE_WAIT		100000
+
+u8 cpu_mask;
+
+/*-------------------------------------------------------------------------
+ * Omap2 specific clock functions
+ *-------------------------------------------------------------------------*/
+
+/**
+ * omap2_init_clksel_parent - set a clksel clk's parent field from the hardware
+ * @clk: OMAP clock struct ptr to use
+ *
+ * Given a pointer to a source-selectable struct clk, read the hardware
+ * register and determine what its parent is currently set to.  Update the
+ * clk->parent field with the appropriate clk ptr.
+ */
+void omap2_init_clksel_parent(struct clk *clk)
+{
+	const struct clksel *clks;
+	const struct clksel_rate *clkr;
+	u32 r, found = 0;
+
+	if (!clk->clksel)
+		return;
+
+	r = __raw_readl(clk->clksel_reg) & clk->clksel_mask;
+	r >>= __ffs(clk->clksel_mask);
+
+	for (clks = clk->clksel; clks->parent && !found; clks++) {
+		for (clkr = clks->rates; clkr->div && !found; clkr++) {
+			if ((clkr->flags & cpu_mask) && (clkr->val == r)) {
+				if (clk->parent != clks->parent) {
+					pr_debug("clock: inited %s parent "
+						 "to %s (was %s)\n",
+						 clk->name, clks->parent->name,
+						 ((clk->parent) ?
+						  clk->parent->name : "NULL"));
+					clk->parent = clks->parent;
+				};
+				found = 1;
+			}
+		}
+	}
+
+	if (!found)
+		printk(KERN_ERR "clock: init parent: could not find "
+		       "regval %0x for clock %s\n", r,  clk->name);
+
+	return;
+}
+
+/* Returns the DPLL rate */
+u32 omap2_get_dpll_rate(struct clk *clk)
+{
+	long long dpll_clk;
+	u32 dpll_mult, dpll_div, dpll;
+	const struct dpll_data *dd;
+
+	dd = clk->dpll_data;
+	/* REVISIT: What do we return on error? */
+	if (!dd)
+		return 0;
+
+	dpll = __raw_readl(dd->mult_div1_reg);
+	dpll_mult = dpll & dd->mult_mask;
+	dpll_mult >>= __ffs(dd->mult_mask);
+	dpll_div = dpll & dd->div1_mask;
+	dpll_div >>= __ffs(dd->div1_mask);
+
+	dpll_clk = (long long)clk->parent->rate * dpll_mult;
+	do_div(dpll_clk, dpll_div + 1);
+
+	/* 34XX only */
+	if (dd->div2_reg) {
+		dpll = __raw_readl(dd->div2_reg);
+		dpll_div = dpll & dd->div2_mask;
+		dpll_div >>= __fss(dd->div2_mask);
+		do_div(dpll_clk, dpll_div + 1);
+	}
+
+	return dpll_clk;
+}
+
+/*
+ * Used for clocks that have the same value as the parent clock,
+ * divided by some factor
+ */
+void omap2_fixed_divisor_recalc(struct clk *clk)
+{
+	WARN_ON(!clk->fixed_div);
+
+	clk->rate = clk->parent->rate / clk->fixed_div;
+
+	if (clk->flags & RATE_PROPAGATES)
+		propagate_rate(clk);
+}
+
+/**
+ * omap2_wait_clock_ready - wait for clock to enable
+ * @reg: physical address of clock IDLEST register
+ * @mask: value to mask against to determine if the clock is active
+ * @name: name of the clock (for printk)
+ *
+ * Returns 1 if the clock enabled in time, or 0 if it failed to enable
+ * in roughly MAX_CLOCK_ENABLE_WAIT microseconds.
+ */
+int omap2_wait_clock_ready(void __iomem *reg, u32 mask, const char *name)
+{
+	int i = 0;
+	int ena = 0;
+
+	/*
+	 * 24xx uses 0 to indicate not ready, and 1 to indicate ready.
+	 * 34xx reverses this, just to keep us on our toes
+	 */
+	if (cpu_mask & (RATE_IN_242X | RATE_IN_243X)) {
+		ena = mask;
+	} else if (cpu_mask & RATE_IN_343X) {
+		ena = 0;
+	}
+
+	/* Wait for lock */
+	while (((__raw_readl(reg) & mask) != ena) &&
+	       (i++ < MAX_CLOCK_ENABLE_WAIT)) {
+		udelay(1);
+	}
+
+	if (i < MAX_CLOCK_ENABLE_WAIT)
+		pr_debug("Clock %s stable after %d loops\n", name, i);
+	else
+		printk(KERN_ERR "Clock %s didn't enable in %d tries\n",
+		       name, MAX_CLOCK_ENABLE_WAIT);
+
+
+	return (i < MAX_CLOCK_ENABLE_WAIT) ? 1 : 0;
+};
+
+
+/*
+ * Note: We don't need special code here for INVERT_ENABLE
+ * for the time being since INVERT_ENABLE only applies to clocks enabled by
+ * CM_CLKEN_PLL
+ */
+static void omap2_clk_wait_ready(struct clk *clk)
+{
+	void __iomem *reg, *other_reg, *st_reg;
+	u32 bit;
+
+	/*
+	 * REVISIT: This code is pretty ugly.  It would be nice to generalize
+	 * it and pull it into struct clk itself somehow.
+	 */
+	reg = clk->enable_reg;
+	if ((((u32)reg & 0xff) >= CM_FCLKEN1) &&
+	    (((u32)reg & 0xff) <= OMAP24XX_CM_FCLKEN2))
+		other_reg = (void __iomem *)(((u32)reg & ~0xf0) | 0x10); /* CM_ICLKEN* */
+	else if ((((u32)reg & 0xff) >= CM_ICLKEN1) &&
+		 (((u32)reg & 0xff) <= OMAP24XX_CM_ICLKEN4))
+		other_reg = (void __iomem *)(((u32)reg & ~0xf0) | 0x00); /* CM_FCLKEN* */
+	else
+		return;
+
+	/* REVISIT: What are the appropriate exclusions for 34XX? */
+	/* No check for DSS or cam clocks */
+	if (cpu_is_omap24xx() && ((u32)reg & 0x0f) == 0) { /* CM_{F,I}CLKEN1 */
+		if (clk->enable_bit == OMAP24XX_EN_DSS2_SHIFT ||
+		    clk->enable_bit == OMAP24XX_EN_DSS1_SHIFT ||
+		    clk->enable_bit == OMAP24XX_EN_CAM_SHIFT)
+			return;
+	}
+
+	/* REVISIT: What are the appropriate exclusions for 34XX? */
+	/* OMAP3: ignore DSS-mod clocks */
+	if (cpu_is_omap34xx() &&
+	    (((u32)reg & ~0xff) == (u32)OMAP_CM_REGADDR(OMAP3430_DSS_MOD, 0)))
+		return;
+
+	/* Check if both functional and interface clocks
+	 * are running. */
+	bit = 1 << clk->enable_bit;
+	if (!(__raw_readl(other_reg) & bit))
+		return;
+	st_reg = (void __iomem *)(((u32)other_reg & ~0xf0) | 0x20); /* CM_IDLEST* */
+
+	omap2_wait_clock_ready(st_reg, bit, clk->name);
+}
+
+/* Enables clock without considering parent dependencies or use count
+ * REVISIT: Maybe change this to use clk->enable like on omap1?
+ */
+int _omap2_clk_enable(struct clk *clk)
+{
+	u32 regval32;
+
+	if (clk->flags & (ALWAYS_ENABLED | PARENT_CONTROLS_CLOCK))
+		return 0;
+
+	if (clk->enable)
+		return clk->enable(clk);
+
+	if (unlikely(clk->enable_reg == 0)) {
+		printk(KERN_ERR "clock.c: Enable for %s without enable code\n",
+		       clk->name);
+		return 0; /* REVISIT: -EINVAL */
+	}
+
+	regval32 = __raw_readl(clk->enable_reg);
+	if (clk->flags & INVERT_ENABLE)
+		regval32 &= ~(1 << clk->enable_bit);
+	else
+		regval32 |= (1 << clk->enable_bit);
+	__raw_writel(regval32, clk->enable_reg);
+	wmb();
+
+	omap2_clk_wait_ready(clk);
+
+	return 0;
+}
+
+/* Disables clock without considering parent dependencies or use count */
+void _omap2_clk_disable(struct clk *clk)
+{
+	u32 regval32;
+
+	if (clk->flags & (ALWAYS_ENABLED | PARENT_CONTROLS_CLOCK))
+		return;
+
+	if (clk->disable) {
+		clk->disable(clk);
+		return;
+	}
+
+	if (clk->enable_reg == 0) {
+		/*
+		 * 'Independent' here refers to a clock which is not
+		 * controlled by its parent.
+		 */
+		printk(KERN_ERR "clock: clk_disable called on independent "
+		       "clock %s which has no enable_reg\n", clk->name);
+		return;
+	}
+
+	regval32 = __raw_readl(clk->enable_reg);
+	if (clk->flags & INVERT_ENABLE)
+		regval32 |= (1 << clk->enable_bit);
+	else
+		regval32 &= ~(1 << clk->enable_bit);
+	__raw_writel(regval32, clk->enable_reg);
+	wmb();
+}
+
+void omap2_clk_disable(struct clk *clk)
+{
+	if (clk->usecount > 0 && !(--clk->usecount)) {
+		_omap2_clk_disable(clk);
+		if (likely((u32)clk->parent))
+			omap2_clk_disable(clk->parent);
+	}
+}
+
+int omap2_clk_enable(struct clk *clk)
+{
+	int ret = 0;
+
+	if (clk->usecount++ == 0) {
+		if (likely((u32)clk->parent))
+			ret = omap2_clk_enable(clk->parent);
+
+		if (unlikely(ret != 0)) {
+			clk->usecount--;
+			return ret;
+		}
+
+		ret = _omap2_clk_enable(clk);
+
+		if (unlikely(ret != 0) && clk->parent) {
+			omap2_clk_disable(clk->parent);
+			clk->usecount--;
+		}
+	}
+
+	return ret;
+}
+
+/*
+ * Used for clocks that are part of CLKSEL_xyz governed clocks.
+ * REVISIT: Maybe change to use clk->enable() functions like on omap1?
+ */
+void omap2_clksel_recalc(struct clk *clk)
+{
+	u32 div = 0;
+
+	pr_debug("clock: recalc'ing clksel clk %s\n", clk->name);
+
+	div = omap2_clksel_get_divisor(clk);
+	if (div == 0)
+		return;
+
+	if (unlikely(clk->rate == clk->parent->rate / div))
+		return;
+	clk->rate = clk->parent->rate / div;
+
+	pr_debug("clock: new clock rate is %ld (div %d)\n", clk->rate, div);
+
+	if (unlikely(clk->flags & RATE_PROPAGATES))
+		propagate_rate(clk);
+}
+
+/**
+ * omap2_get_clksel_by_parent - return clksel struct for a given clk & parent
+ * @clk: OMAP struct clk ptr to inspect
+ * @src_clk: OMAP struct clk ptr of the parent clk to search for
+ *
+ * Scan the struct clksel array associated with the clock to find
+ * the element associated with the supplied parent clock address.
+ * Returns a pointer to the struct clksel on success or NULL on error.
+ */
+const struct clksel *omap2_get_clksel_by_parent(struct clk *clk,
+						struct clk *src_clk)
+{
+	const struct clksel *clks;
+
+	if (!clk->clksel)
+		return NULL;
+
+	for (clks = clk->clksel; clks->parent; clks++) {
+		if (clks->parent == src_clk)
+			break; /* Found the requested parent */
+	}
+
+	if (!clks->parent) {
+		printk(KERN_ERR "clock: Could not find parent clock %s in "
+		       "clksel array of clock %s\n", src_clk->name,
+		       clk->name);
+		return NULL;
+	}
+
+	return clks;
+}
+
+/**
+ * omap2_clksel_round_rate_div - find divisor for the given clock and rate
+ * @clk: OMAP struct clk to use
+ * @target_rate: desired clock rate
+ * @new_div: ptr to where we should store the divisor
+ *
+ * Finds 'best' divider value in an array based on the source and target
+ * rates.  The divider array must be sorted with smallest divider first.
+ * Note that this will not work for clocks which are part of CONFIG_PARTICIPANT,
+ * they are only settable as part of virtual_prcm set.
+ *
+ * Returns the rounded clock rate or returns 0xffffffff on error.
+ */
+u32 omap2_clksel_round_rate_div(struct clk *clk, unsigned long target_rate,
+				u32 *new_div)
+{
+	unsigned long test_rate;
+	const struct clksel *clks;
+	const struct clksel_rate *clkr;
+	u32 last_div = 0;
+
+	printk(KERN_INFO "clock: clksel_round_rate_div: %s target_rate %ld\n",
+	       clk->name, target_rate);
+
+	*new_div = 1;
+
+	clks = omap2_get_clksel_by_parent(clk, clk->parent);
+	if (clks == NULL)
+		return ~0;
+
+	for (clkr = clks->rates; clkr->div; clkr++) {
+		if (!(clkr->flags & cpu_mask))
+		    continue;
+
+		/* Sanity check */
+		if (clkr->div <= last_div)
+			printk(KERN_ERR "clock: clksel_rate table not sorted "
+			       "for clock %s", clk->name);
+
+		last_div = clkr->div;
+
+		test_rate = clk->parent->rate / clkr->div;
+
+		if (test_rate <= target_rate)
+			break; /* found it */
+	}
+
+	if (!clkr->div) {
+		printk(KERN_ERR "clock: Could not find divisor for target "
+		       "rate %ld for clock %s parent %s\n", target_rate,
+		       clk->name, clk->parent->name);
+		return ~0;
+	}
+
+	*new_div = clkr->div;
+
+	printk(KERN_INFO "clock: new_div = %d, new_rate = %ld\n", *new_div,
+	       (clk->parent->rate / clkr->div));
+
+	return (clk->parent->rate / clkr->div);
+}
+
+/**
+ * omap2_clksel_round_rate - find rounded rate for the given clock and rate
+ * @clk: OMAP struct clk to use
+ * @target_rate: desired clock rate
+ *
+ * Compatibility wrapper for OMAP clock framework
+ * Finds best target rate based on the source clock and possible dividers.
+ * rates. The divider array must be sorted with smallest divider first.
+ * Note that this will not work for clocks which are part of CONFIG_PARTICIPANT,
+ * they are only settable as part of virtual_prcm set.
+ *
+ * Returns the rounded clock rate or returns 0xffffffff on error.
+ */
+long omap2_clksel_round_rate(struct clk *clk, unsigned long target_rate)
+{
+	u32 new_div;
+
+	return omap2_clksel_round_rate_div(clk, target_rate, &new_div);
+}
+
+
+/* Given a clock and a rate apply a clock specific rounding function */
+long omap2_clk_round_rate(struct clk *clk, unsigned long rate)
+{
+	if (clk->round_rate != 0)
+		return clk->round_rate(clk, rate);
+
+	if (clk->flags & RATE_FIXED)
+		printk(KERN_ERR "clock: generic omap2_clk_round_rate called "
+		       "on fixed-rate clock %s\n", clk->name);
+
+	return clk->rate;
+}
+
+/**
+ * omap2_clksel_to_divisor() - turn clksel field value into integer divider
+ * @clk: OMAP struct clk to use
+ * @field_val: register field value to find
+ *
+ * Given a struct clk of a rate-selectable clksel clock, and a register field
+ * value to search for, find the corresponding clock divisor.  The register
+ * field value should be pre-masked and shifted down so the LSB is at bit 0
+ * before calling.  Returns 0 on error
+ */
+u32 omap2_clksel_to_divisor(struct clk *clk, u32 field_val)
+{
+	const struct clksel *clks;
+	const struct clksel_rate *clkr;
+
+	clks = omap2_get_clksel_by_parent(clk, clk->parent);
+	if (clks == NULL)
+		return 0;
+
+	for (clkr = clks->rates; clkr->div; clkr++) {
+		if ((clkr->flags & cpu_mask) && (clkr->val == field_val))
+			break;
+	}
+
+	if (!clkr->div) {
+		printk(KERN_ERR "clock: Could not find fieldval %d for "
+		       "clock %s parent %s\n", field_val, clk->name,
+		       clk->parent->name);
+		return 0;
+	}
+
+	return clkr->div;
+}
+
+/**
+ * omap2_divisor_to_clksel() - turn clksel integer divisor into a field value
+ * @clk: OMAP struct clk to use
+ * @div: integer divisor to search for
+ *
+ * Given a struct clk of a rate-selectable clksel clock, and a clock divisor,
+ * find the corresponding register field value.  The return register value is
+ * the value before left-shifting.  Returns 0xffffffff on error
+ */
+u32 omap2_divisor_to_clksel(struct clk *clk, u32 div)
+{
+	const struct clksel *clks;
+	const struct clksel_rate *clkr;
+
+	/* should never happen */
+	WARN_ON(div == 0);
+
+	clks = omap2_get_clksel_by_parent(clk, clk->parent);
+	if (clks == NULL)
+		return 0;
+
+	for (clkr = clks->rates; clkr->div; clkr++) {
+		if ((clkr->flags & cpu_mask) && (clkr->div == div))
+			break;
+	}
+
+	if (!clkr->div) {
+		printk(KERN_ERR "clock: Could not find divisor %d for "
+		       "clock %s parent %s\n", div, clk->name,
+		       clk->parent->name);
+		return 0;
+	}
+
+	return clkr->val;
+}
+
+/**
+ * omap2_get_clksel - find clksel register addr & field mask for a clk
+ * @clk: struct clk to use
+ * @field_mask: ptr to u32 to store the register field mask
+ *
+ * Returns the address of the clksel register upon success or NULL on error.
+ */
+void __iomem *omap2_get_clksel(struct clk *clk, u32 *field_mask)
+{
+	if (unlikely((clk->clksel_reg == 0) || (clk->clksel_mask == 0)))
+		return NULL;
+
+	*field_mask = clk->clksel_mask;
+
+	return clk->clksel_reg;
+}
+
+/**
+ * omap2_clksel_get_divisor - get current divider applied to parent clock.
+ * @clk: OMAP struct clk to use.
+ *
+ * Returns the integer divisor upon success or 0 on error.
+ */
+u32 omap2_clksel_get_divisor(struct clk *clk)
+{
+	u32 field_mask, field_val;
+	void __iomem *div_addr;
+
+	div_addr = omap2_get_clksel(clk, &field_mask);
+	if (div_addr == 0)
+		return 0;
+
+	field_val = __raw_readl(div_addr) & field_mask;
+	field_val >>= __ffs(field_mask);
+
+	return omap2_clksel_to_divisor(clk, field_val);
+}
+
+int omap2_clksel_set_rate(struct clk *clk, unsigned long rate)
+{
+	u32 field_mask, field_val, reg_val, validrate, new_div = 0;
+	void __iomem *div_addr;
+
+	validrate = omap2_clksel_round_rate_div(clk, rate, &new_div);
+	if (validrate != rate)
+		return -EINVAL;
+
+	div_addr = omap2_get_clksel(clk, &field_mask);
+	if (div_addr == 0)
+		return -EINVAL;
+
+	field_val = omap2_divisor_to_clksel(clk, new_div);
+	if (field_val == ~0)
+		return -EINVAL;
+
+	reg_val = __raw_readl(div_addr);
+	reg_val &= ~field_mask;
+	reg_val |= (field_val << __ffs(field_mask));
+	__raw_writel(reg_val, div_addr);
+	wmb();
+
+	clk->rate = clk->parent->rate / new_div;
+
+	if (clk->flags & DELAYED_APP && cpu_is_omap24xx()) {
+		__raw_writel(OMAP24XX_VALID_CONFIG, OMAP24XX_PRCM_CLKCFG_CTRL);
+		wmb();
+	}
+
+	return 0;
+}
+
+
+/* Set the clock rate for a clock source */
+int omap2_clk_set_rate(struct clk *clk, unsigned long rate)
+{
+	int ret = -EINVAL;
+
+	pr_debug("clock: set_rate for clock %s to rate %ld\n", clk->name, rate);
+
+	/* CONFIG_PARTICIPANT clocks are changed only in sets via the
+	   rate table mechanism, driven by mpu_speed  */
+	if (clk->flags & CONFIG_PARTICIPANT)
+		return -EINVAL;
+
+	/* dpll_ck, core_ck, virt_prcm_set; plus all clksel clocks */
+	if (clk->set_rate != 0)
+		ret = clk->set_rate(clk, rate);
+
+	if (unlikely(ret == 0 && (clk->flags & RATE_PROPAGATES)))
+		propagate_rate(clk);
+
+	return ret;
+}
+
+/*
+ * Converts encoded control register address into a full address
+ * On error, *src_addr will be returned as 0.
+ */
+static u32 omap2_clksel_get_src_field(void __iomem **src_addr,
+				      struct clk *src_clk, u32 *field_mask,
+				      struct clk *clk, u32 *parent_div)
+{
+	const struct clksel *clks;
+	const struct clksel_rate *clkr;
+
+	*parent_div = 0;
+	*src_addr = 0;
+
+	clks = omap2_get_clksel_by_parent(clk, src_clk);
+	if (clks == NULL)
+		return 0;
+
+	for (clkr = clks->rates; clkr->div; clkr++) {
+		if (clkr->flags & (cpu_mask | DEFAULT_RATE))
+			break; /* Found the default rate for this platform */
+	}
+
+	if (!clkr->div) {
+		printk(KERN_ERR "clock: Could not find default rate for "
+		       "clock %s parent %s\n", clk->name,
+		       src_clk->parent->name);
+		return 0;
+	}
+
+	/* Should never happen.  Add a clksel mask to the struct clk. */
+	WARN_ON(clk->clksel_mask == 0);
+
+	*field_mask = clk->clksel_mask;
+	*src_addr = clk->clksel_reg;
+	*parent_div = clkr->div;
+
+	return clkr->val;
+}
+
+int omap2_clk_set_parent(struct clk *clk, struct clk *new_parent)
+{
+	void __iomem *src_addr;
+	u32 field_val, field_mask, reg_val, parent_div;
+
+	if (unlikely(clk->flags & CONFIG_PARTICIPANT))
+		return -EINVAL;
+
+	if (!clk->clksel)
+		return -EINVAL;
+
+	field_val = omap2_clksel_get_src_field(&src_addr, new_parent,
+					       &field_mask, clk, &parent_div);
+	if (src_addr == 0)
+		return -EINVAL;
+
+	if (clk->usecount > 0)
+		_omap2_clk_disable(clk);
+
+	/* Set new source value (previous dividers if any in effect) */
+	reg_val = __raw_readl(src_addr) & ~field_mask;
+	reg_val |= (field_val << __ffs(field_mask));
+	__raw_writel(reg_val, src_addr);
+	wmb();
+
+	if (clk->flags & DELAYED_APP && cpu_is_omap24xx()) {
+		__raw_writel(OMAP24XX_VALID_CONFIG, OMAP24XX_PRCM_CLKCFG_CTRL);
+		wmb();
+	}
+
+	if (clk->usecount > 0)
+		_omap2_clk_enable(clk);
+
+	clk->parent = new_parent;
+
+	/* CLKSEL clocks follow their parents' rates, divided by a divisor */
+	clk->rate = new_parent->rate;
+
+	if (parent_div > 0)
+		clk->rate /= parent_div;
+
+	pr_debug("clock: set parent of %s to %s (new rate %ld)\n",
+		 clk->name, clk->parent->name, clk->rate);
+
+	if (unlikely(clk->flags & RATE_PROPAGATES))
+		propagate_rate(clk);
+
+	return 0;
+}
+
+/*-------------------------------------------------------------------------
+ * Omap2 clock reset and init functions
+ *-------------------------------------------------------------------------*/
+
+#ifdef CONFIG_OMAP_RESET_CLOCKS
+void omap2_clk_disable_unused(struct clk *clk)
+{
+	u32 regval32, v;
+
+	v = (clk->flags & INVERT_ENABLE) ? (1 << clk->enable_bit) : 0;
+
+	regval32 = __raw_readl(clk->enable_reg);
+	if ((regval32 & (1 << clk->enable_bit)) == v)
+		return;
+
+	printk(KERN_INFO "Disabling unused clock \"%s\"\n", clk->name);
+	_omap2_clk_disable(clk);
+}
+#endif

arch/arm/mach-omap2/clock.h

+/*
+ *  linux/arch/arm/mach-omap2/clock.h
+ *
+ *  Copyright (C) 2005 Texas Instruments Inc.
+ *  Richard Woodruff <r-woodruff2@ti.com>
+ *  Created for OMAP2.
+ *
+ *  Copyright (C) 2004 Nokia corporation
+ *  Written by Tuukka Tikkanen <tuukka.tikkanen@elektrobit.com>
+ *  Based on clocks.h by Tony Lindgren, Gordon McNutt and RidgeRun, Inc
+ *
+ *  Copyright (C) 2007 Texas Instruments, Inc.
+ *  Copyright (C) 2007 Nokia Corporation
+ *  Paul Walmsley
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef __ARCH_ARM_MACH_OMAP2_CLOCK_H
+#define __ARCH_ARM_MACH_OMAP2_CLOCK_H
+
+#include <asm/arch/clock.h>
+
+int omap2_clk_enable(struct clk *clk);
+void omap2_clk_disable(struct clk *clk);
+long omap2_clk_round_rate(struct clk *clk, unsigned long rate);
+int omap2_clk_set_rate(struct clk *clk, unsigned long rate);
+int omap2_clk_set_parent(struct clk *clk, struct clk *new_parent);
+
+#ifdef CONFIG_OMAP_RESET_CLOCKS
+void omap2_clk_disable_unused(struct clk *clk);
+#else
+#define omap2_clk_disable_unused	NULL
+#endif
+
+void omap2_clksel_recalc(struct clk *clk);
+void omap2_init_clksel_parent(struct clk *clk);
+u32 omap2_clksel_get_divisor(struct clk *clk);
+u32 omap2_clksel_round_rate_div(struct clk *clk, unsigned long target_rate,
+				u32 *new_div);
+u32 omap2_clksel_to_divisor(struct clk *clk, u32 field_val);
+u32 omap2_divisor_to_clksel(struct clk *clk, u32 div);
+void omap2_fixed_divisor_recalc(struct clk *clk);
+long omap2_clksel_round_rate(struct clk *clk, unsigned long target_rate);
+int omap2_clksel_set_rate(struct clk *clk, unsigned long rate);
+u32 omap2_get_dpll_rate(struct clk *clk);
+int omap2_wait_clock_ready(void __iomem *reg, u32 cval, const char *name);
+
+extern u8 cpu_mask;
+
+/* clksel_rate data common to 24xx/343x */
+static const struct clksel_rate gpt_32k_rates[] = {
+	 { .div = 1, .val = 0, .flags = RATE_IN_24XX | RATE_IN_343X | DEFAULT_RATE },
+	 { .div = 0 }
+};
+
+static const struct clksel_rate gpt_sys_rates[] = {
+	 { .div = 1, .val = 1, .flags = RATE_IN_24XX | RATE_IN_343X | DEFAULT_RATE },
+	 { .div = 0 }
+};
+
+static const struct clksel_rate gfx_l3_rates[] = {
+	{ .div = 1, .val = 1, .flags = RATE_IN_24XX | RATE_IN_343X },
+	{ .div = 2, .val = 2, .flags = RATE_IN_24XX | RATE_IN_343X | DEFAULT_RATE },
+	{ .div = 3, .val = 3, .flags = RATE_IN_243X | RATE_IN_343X },
+	{ .div = 4, .val = 4, .flags = RATE_IN_243X | RATE_IN_343X },
+	{ .div = 0 }
+};
+
+
+#endif