/*
* linux/arch/arm/mach-omap2/clock.c
*
* Copyright (C) 2005-2008 Texas Instruments, Inc.
* Copyright (C) 2004-2008 Nokia Corporation
*
* Contacts:
* Richard Woodruff <r-woodruff2@ti.com>
* 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.
*/
#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 <linux/io.h>
#include <linux/bitops.h>
#include <mach/clock.h>
#include <mach/clockdomain.h>
#include <mach/sram.h>
#include <mach/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
/* DPLL rate rounding: minimum DPLL multiplier, divider values */
#define DPLL_MIN_MULTIPLIER 1
#define DPLL_MIN_DIVIDER 1
/* Possible error results from _dpll_test_mult */
#define DPLL_MULT_UNDERFLOW (1 << 0)
/*
* Scale factor to mitigate roundoff errors in DPLL rate rounding.
* The higher the scale factor, the greater the risk of arithmetic overflow,
* but the closer the rounded rate to the target rate. DPLL_SCALE_FACTOR
* must be a power of DPLL_SCALE_BASE.
*/
#define DPLL_SCALE_FACTOR 64
#define DPLL_SCALE_BASE 2
#define DPLL_ROUNDING_VAL ((DPLL_SCALE_BASE / 2) * \
(DPLL_SCALE_FACTOR / DPLL_SCALE_BASE))
u8 cpu_mask;
/*-------------------------------------------------------------------------
* OMAP2/3 specific clock functions
*-------------------------------------------------------------------------*/
/**
* omap2_init_clk_clkdm - look up a clockdomain name, store pointer in clk
* @clk: OMAP clock struct ptr to use
*
* Convert a clockdomain name stored in a struct clk 'clk' into a
* clockdomain pointer, and save it into the struct clk. Intended to be
* called during clk_register(). No return value.
*/
void omap2_init_clk_clkdm(struct clk *clk)
{
struct clockdomain *clkdm;
if (!clk->clkdm_name)
return;
clkdm = clkdm_lookup(clk->clkdm_name);
if (clkdm) {
pr_debug("clock: associated clk %s to clkdm %s\n",
clk->name, clk->clkdm_name);
clk->clkdm = clkdm;
} else {
pr_debug("clock: could not associate clk %s to "
"clkdm %s\n", clk->name, clk->clkdm_name);
}
}
/**
* 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;
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);
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) ||
((((u32)reg & ~0xff) == (u32)OMAP_CM_REGADDR(CORE_MOD, 0)) &&
clk->enable_bit == OMAP3430_EN_SSI_SHIFT)))
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 == NULL)) {
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 == NULL) {
/*
* '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);
if (clk->clkdm)
omap2_clkdm_clk_disable(clk->clkdm, clk);
}
}
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;
}
if (clk->clkdm)
omap2_clkdm_clk_enable(clk->clkdm, clk);
ret = _omap2_clk_enable(clk);
if (unlikely(ret != 0)) {
if (clk->clkdm)
omap2_clkdm_clk_disable(clk->clkdm, clk);
if (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 != NULL)
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 == NULL) || (clk->clksel_mask == NULL)))
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 == NULL)
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 == NULL)
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()) {
prm_write_mod_reg(OMAP24XX_VALID_CONFIG,
OMAP24XX_GR_MOD, OMAP24XX_PRCM_CLKCFG_CTRL_OFFSET);
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 != NULL)
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 = NULL;
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 == NULL)
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;
}
/* DPLL rate rounding code */
/**
* omap2_dpll_set_rate_tolerance: set the error tolerance during rate rounding
* @clk: struct clk * of the DPLL
* @tolerance: maximum rate error tolerance
*
* Set the maximum DPLL rate error tolerance for the rate rounding
* algorithm. The rate tolerance is an attempt to balance DPLL power
* saving (the least divider value "n") vs. rate fidelity (the least
* difference between the desired DPLL target rate and the rounded
* rate out of the algorithm). So, increasing the tolerance is likely
* to decrease DPLL power consumption and increase DPLL rate error.
* Returns -EINVAL if provided a null clock ptr or a clk that is not a
* DPLL; or 0 upon success.
*/
int omap2_dpll_set_rate_tolerance(struct clk *clk, unsigned int tolerance)
{
if (!clk || !clk->dpll_data)
return -EINVAL;
clk->dpll_data->rate_tolerance = tolerance;
return 0;
}
static unsigned long _dpll_compute_new_rate(unsigned long parent_rate, unsigned int m, unsigned int n)
{
unsigned long long num;
num = (unsigned long long)parent_rate * m;
do_div(num, n);
return num;
}
/*
* _dpll_test_mult - test a DPLL multiplier value
* @m: pointer to the DPLL m (multiplier) value under test
* @n: current DPLL n (divider) value under test
* @new_rate: pointer to storage for the resulting rounded rate
* @target_rate: the desired DPLL rate
* @parent_rate: the DPLL's parent clock rate
*
* This code tests a DPLL multiplier value, ensuring that the
* resulting rate will not be higher than the target_rate, and that
* the multiplier value itself is valid for the DPLL. Initially, the
* integer pointed to by the m argument should be prescaled by
* multiplying by DPLL_SCALE_FACTOR. The code will replace this with
* a non-scaled m upon return. This non-scaled m will result in a
* new_rate as close as possible to target_rate (but not greater than
* target_rate) given the current (parent_rate, n, prescaled m)
* triple. Returns DPLL_MULT_UNDERFLOW in the event that the
* non-scaled m attempted to underflow, which can allow the calling
* function to bail out early; or 0 upon success.
*/
static int _dpll_test_mult(int *m, int n, unsigned long *new_rate,
unsigned long target_rate,
unsigned long parent_rate)
{
int flags = 0, carry = 0;
/* Unscale m and round if necessary */
if (*m % DPLL_SCALE_FACTOR >= DPLL_ROUNDING_VAL)
carry = 1;
*m = (*m / DPLL_SCALE_FACTOR) + carry;
/*
* The new rate must be <= the target rate to avoid programming
* a rate that is impossible for the hardware to handle
*/
*new_rate = _dpll_compute_new_rate(parent_rate, *m, n);
if (*new_rate > target_rate) {
(*m)--;
*new_rate = 0;
}
/* Guard against m underflow */
if (*m < DPLL_MIN_MULTIPLIER) {
*m = DPLL_MIN_MULTIPLIER;
*new_rate = 0;
flags = DPLL_MULT_UNDERFLOW;
}
if (*new_rate == 0)
*new_rate = _dpll_compute_new_rate(parent_rate, *m, n);
return flags;
}
/**
* omap2_dpll_round_rate - round a target rate for an OMAP DPLL
* @clk: struct clk * for a DPLL
* @target_rate: desired DPLL clock rate
*
* Given a DPLL, a desired target rate, and a rate tolerance, round
* the target rate to a possible, programmable rate for this DPLL.
* Rate tolerance is assumed to be set by the caller before this
* function is called. Attempts to select the minimum possible n
* within the tolerance to reduce power consumption. Stores the
* computed (m, n) in the DPLL's dpll_data structure so set_rate()
* will not need to call this (expensive) function again. Returns ~0
* if the target rate cannot be rounded, either because the rate is
* too low or because the rate tolerance is set too tightly; or the
* rounded rate upon success.
*/
long omap2_dpll_round_rate(struct clk *clk, unsigned long target_rate)
{
int m, n, r, e, scaled_max_m;
unsigned long scaled_rt_rp, new_rate;
int min_e = -1, min_e_m = -1, min_e_n = -1;
if (!clk || !clk->dpll_data)
return ~0;
pr_debug("clock: starting DPLL round_rate for clock %s, target rate "
"%ld\n", clk->name, target_rate);
scaled_rt_rp = target_rate / (clk->parent->rate / DPLL_SCALE_FACTOR);
scaled_max_m = clk->dpll_data->max_multiplier * DPLL_SCALE_FACTOR;
clk->dpll_data->last_rounded_rate = 0;
for (n = clk->dpll_data->max_divider; n >= DPLL_MIN_DIVIDER; n--) {
/* Compute the scaled DPLL multiplier, based on the divider */
m = scaled_rt_rp * n;
/*
* Since we're counting n down, a m overflow means we can
* can immediately skip to the next n
*/
if (m > scaled_max_m)
continue;
r = _dpll_test_mult(&m, n, &new_rate, target_rate,
clk->parent->rate);
e = target_rate - new_rate;
pr_debug("clock: n = %d: m = %d: rate error is %d "
"(new_rate = %ld)\n", n, m, e, new_rate);
if (min_e == -1 ||
min_e >= (int)(abs(e) - clk->dpll_data->rate_tolerance)) {
min_e = e;
min_e_m = m;
min_e_n = n;
pr_debug("clock: found new least error %d\n", min_e);
}
/*
* Since we're counting n down, a m underflow means we
* can bail out completely (since as n decreases in
* the next iteration, there's no way that m can
* increase beyond the current m)
*/
if (r & DPLL_MULT_UNDERFLOW)
break;
}
if (min_e < 0) {
pr_debug("clock: error: target rate or tolerance too low\n");
return ~0;
}
clk->dpll_data->last_rounded_m = min_e_m;
clk->dpll_data->last_rounded_n = min_e_n;
clk->dpll_data->last_rounded_rate =
_dpll_compute_new_rate(clk->parent->rate, min_e_m, min_e_n);
pr_debug("clock: final least error: e = %d, m = %d, n = %d\n",
min_e, min_e_m, min_e_n);
pr_debug("clock: final rate: %ld (target rate: %ld)\n",
clk->dpll_data->last_rounded_rate, target_rate);
return clk->dpll_data->last_rounded_rate;
}
/*-------------------------------------------------------------------------
* 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
