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OMAP2+ clock: clean up clkt_clksel.c 

This patch cleans up arch/arm/mach-omap2/clkt_clksel.c.  It:

- makes several functions static that are not called outside the file;

- adds documentation;

- makes some code paths easier to read (hopefully), by breaking up
  compound statements and removing redundant checks;

- converts some pr_err()s that indicate clock tree data problems into WARN()s,
  so they are more likely to be noticed;

- and moves omap2_clk_round_rate() back into mach-omap2/clock.c, its proper
  home, since it is not clksel-specific.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
This commit is contained in:
Paul Walmsley 2010-05-18 18:40:24 -06:00
parent d74b494971
commit 435699db6a
3 changed files with 301 additions and 212 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

493
arch/arm/mach-omap2/clkt_clksel.c
View File

@ -12,8 +12,26 @@
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* XXX At some point these clksel clocks should be split into
* "divider" clocks and "mux" clocks to better match the hardware.
*
* clksel clocks are clocks that do not have a fixed parent, or that
* can divide their parent's rate, or possibly both at the same time, based
* on the contents of a hardware register bitfield.
*
* All of the various mux and divider settings can be encoded into
* struct clksel* data structures, and then these can be autogenerated
* from some hardware database for each new chip generation. This
* should avoid the need to write, review, and validate a lot of new
* clock code for each new chip, since it can be exported from the SoC
* design flow. This is now done on OMAP4.
*
* The fusion of mux and divider clocks is a software creation. In
* hardware reality, the multiplexer (parent selection) and the
* divider exist separately. XXX At some point these clksel clocks
* should be split into "divider" clocks and "mux" clocks to better
* match the hardware.
*
* (The name "clksel" comes from the name of the corresponding
* register field in the OMAP2/3 family of SoCs.)
*
* XXX Currently these clocks are only used in the OMAP2/3/4 code, but
* many of the OMAP1 clocks should be convertible to use this
@ -29,14 +47,11 @@
#include <plat/clock.h>
#include "clock.h"
#include "cm.h"
#include "cm-regbits-24xx.h"
#include "cm-regbits-34xx.h"
/* Private functions */
/**
* _omap2_get_clksel_by_parent - return clksel struct for a given clk & parent
* _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
*
@ -44,23 +59,19 @@
* the element associated with the supplied parent clock address.
* Returns a pointer to the struct clksel on success or NULL on error.
*/
static const struct clksel *_omap2_get_clksel_by_parent(struct clk *clk,
struct clk *src_clk)
static const struct clksel *_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++) {
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);
/* This indicates a data problem */
WARN(1, "clock: Could not find parent clock %s in clksel array "
"of clock %s\n", src_clk->name, clk->name);
return NULL;
}
@ -68,7 +79,7 @@ static const struct clksel *_omap2_get_clksel_by_parent(struct clk *clk,
}
/**
* _omap2_clksel_get_src_field - find the new clksel divisor to use
* _get_div_and_fieldval() - find the new clksel divisor and field value to use
* @src_clk: planned new parent struct clk *
* @clk: struct clk * that is being reparented
* @field_val: pointer to a u32 to contain the register data for the divisor
@ -82,14 +93,14 @@ static const struct clksel *_omap2_get_clksel_by_parent(struct clk *clk,
* success (in this latter case, the corresponding register bitfield
* value is passed back in the variable pointed to by @field_val)
*/
static u8 _omap2_clksel_get_src_field(struct clk *src_clk, struct clk *clk,
u32 *field_val)
static u8 _get_div_and_fieldval(struct clk *src_clk, struct clk *clk,
u32 *field_val)
{
const struct clksel *clks;
const struct clksel_rate *clkr, *max_clkr;
u8 max_div = 0;
clks = _omap2_get_clksel_by_parent(clk, src_clk);
clks = _get_clksel_by_parent(clk, src_clk);
if (!clks)
return 0;
@ -113,9 +124,9 @@ static u8 _omap2_clksel_get_src_field(struct clk *src_clk, struct clk *clk,
}
if (max_div == 0) {
WARN(1, "clock: Could not find divisor for "
"clock %s parent %s\n", clk->name,
src_clk->parent->name);
/* This indicates an error in the clksel data */
WARN(1, "clock: Could not find divisor for clock %s parent %s"
"\n", clk->name, src_clk->parent->name);
return 0;
}
@ -124,82 +135,141 @@ static u8 _omap2_clksel_get_src_field(struct clk *src_clk, struct clk *clk,
return max_div;
}
/**
* _write_clksel_reg() - program a clock's clksel register in hardware
* @clk: struct clk * to program
* @v: clksel bitfield value to program (with LSB at bit 0)
*
* Shift the clksel register bitfield value @v to its appropriate
* location in the clksel register and write it in. This function
* will ensure that the write to the clksel_reg reaches its
* destination before returning -- important since PRM and CM register
* accesses can be quite slow compared to ARM cycles -- but does not
* take into account any time the hardware might take to switch the
* clock source.
*/
static void _write_clksel_reg(struct clk *clk, u32 field_val)
{
u32 v;
v = __raw_readl(clk->clksel_reg);
v &= ~clk->clksel_mask;
v |= field_val << __ffs(clk->clksel_mask);
__raw_writel(v, clk->clksel_reg);
v = __raw_readl(clk->clksel_reg); /* OCP barrier */
}
/**
* _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 or returns the actual integer divisor
* upon success.
*/
static u32 _clksel_to_divisor(struct clk *clk, u32 field_val)
{
const struct clksel *clks;
const struct clksel_rate *clkr;
clks = _get_clksel_by_parent(clk, clk->parent);
if (!clks)
return 0;
for (clkr = clks->rates; clkr->div; clkr++) {
if (!(clkr->flags & cpu_mask))
continue;
if (clkr->val == field_val)
break;
}
if (!clkr->div) {
/* This indicates a data error */
WARN(1, "clock: Could not find fieldval %d for clock %s parent "
"%s\n", field_val, clk->name, clk->parent->name);
return 0;
}
return clkr->div;
}
/**
* _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. Returns the
* register field value _before_ left-shifting (i.e., LSB is at bit
* 0); or returns 0xFFFFFFFF (~0) upon error.
*/
static u32 _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 = _get_clksel_by_parent(clk, clk->parent);
if (!clks)
return ~0;
for (clkr = clks->rates; clkr->div; clkr++) {
if (!(clkr->flags & cpu_mask))
continue;
if (clkr->div == div)
break;
}
if (!clkr->div) {
pr_err("clock: Could not find divisor %d for clock %s parent "
"%s\n", div, clk->name, clk->parent->name);
return ~0;
}
return clkr->val;
}
/**
* _read_divisor() - get current divisor applied to parent clock (from hdwr)
* @clk: OMAP struct clk to use.
*
* Read the current divisor register value for @clk that is programmed
* into the hardware, convert it into the actual divisor value, and
* return it; or return 0 on error.
*/
static u32 _read_divisor(struct clk *clk)
{
u32 v;
if (!clk->clksel || !clk->clksel_mask)
return 0;
v = __raw_readl(clk->clksel_reg);
v &= clk->clksel_mask;
v >>= __ffs(clk->clksel_mask);
return _clksel_to_divisor(clk, v);
}
/* Public 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_reparent(clk, 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;
}
/*
* Used for clocks that are part of CLKSEL_xyz governed clocks.
* REVISIT: Maybe change to use clk->enable() functions like on omap1?
*/
unsigned long omap2_clksel_recalc(struct clk *clk)
{
unsigned long rate;
u32 div = 0;
pr_debug("clock: recalc'ing clksel clk %s\n", clk->name);
div = omap2_clksel_get_divisor(clk);
if (div == 0)
return clk->rate;
rate = clk->parent->rate / div;
pr_debug("clock: new clock rate is %ld (div %d)\n", rate, div);
return rate;
}
/**
* omap2_clksel_round_rate_div - find divisor for the given clock and rate
* 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.
* This function is also used by the DPLL3 M2 divider code.
*
* Returns the rounded clock rate or returns 0xffffffff on error.
*/
@ -211,12 +281,15 @@ u32 omap2_clksel_round_rate_div(struct clk *clk, unsigned long target_rate,
const struct clksel_rate *clkr;
u32 last_div = 0;
if (!clk->clksel || !clk->clksel_mask)
return ~0;
pr_debug("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);
clks = _get_clksel_by_parent(clk, clk->parent);
if (!clks)
return ~0;
@ -252,16 +325,92 @@ u32 omap2_clksel_round_rate_div(struct clk *clk, unsigned long target_rate,
return clk->parent->rate / clkr->div;
}
/*
* Clocktype interface functions to the OMAP clock code
* (i.e., those used in struct clk field function pointers, etc.)
*/
/**
* omap2_clksel_round_rate - find rounded rate for the given clock and rate
* omap2_init_clksel_parent() - set a clksel clk's parent field from the hdwr
* @clk: OMAP clock struct ptr to use
*
* Given a pointer @clk to a source-selectable struct clk, read the
* hardware register and determine what its parent is currently set
* to. Update @clk's .parent field with the appropriate clk ptr. No
* return value.
*/
void omap2_init_clksel_parent(struct clk *clk)
{
const struct clksel *clks;
const struct clksel_rate *clkr;
u32 r, found = 0;
if (!clk->clksel || !clk->clksel_mask)
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))
continue;
if (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_reparent(clk, clks->parent);
};
found = 1;
}
}
}
/* This indicates a data error */
WARN(!found, "clock: %s: init parent: could not find regval %0x\n",
clk->name, r);
return;
}
/**
* omap2_clksel_recalc() - function ptr to pass via struct clk .recalc field
* @clk: struct clk *
*
* This function is intended to be called only by the clock framework.
* Each clksel clock should have its struct clk .recalc field set to this
* function. Returns the clock's current rate, based on its parent's rate
* and its current divisor setting in the hardware.
*/
unsigned long omap2_clksel_recalc(struct clk *clk)
{
unsigned long rate;
u32 div = 0;
div = _read_divisor(clk);
if (div == 0)
return clk->rate;
rate = clk->parent->rate / div;
pr_debug("clock: %s: recalc'd rate is %ld (div %d)\n", clk->name,
rate, div);
return rate;
}
/**
* 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
* This function is intended to be called only by the 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.
*/
@ -272,148 +421,78 @@ long omap2_clksel_round_rate(struct clk *clk, unsigned long target_rate)
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)
return clk->round_rate(clk, rate);
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
* omap2_clksel_set_rate() - program clock rate in hardware
* @clk: struct clk * to program rate
* @rate: target rate to program
*
* 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
* This function is intended to be called only by the clock framework.
* Program @clk's rate to @rate in the hardware. The clock can be
* either enabled or disabled when this happens, although if the clock
* is enabled, some downstream devices may glitch or behave
* unpredictably when the clock rate is changed - this depends on the
* hardware. This function does not currently check the usecount of
* the clock, so if multiple drivers are using the clock, and the rate
* is changed, they will all be affected without any notification.
* Returns -EINVAL upon error, or 0 upon success.
*/
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)
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 ~0 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)
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_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 v;
if (!clk->clksel_mask)
return 0;
v = __raw_readl(clk->clksel_reg) & clk->clksel_mask;
v >>= __ffs(clk->clksel_mask);
return omap2_clksel_to_divisor(clk, v);
}
int omap2_clksel_set_rate(struct clk *clk, unsigned long rate)
{
u32 v, field_val, validrate, new_div = 0;
u32 field_val, validrate, new_div = 0;
if (!clk->clksel_mask)
if (!clk->clksel || !clk->clksel_mask)
return -EINVAL;
validrate = omap2_clksel_round_rate_div(clk, rate, &new_div);
if (validrate != rate)
return -EINVAL;
field_val = omap2_divisor_to_clksel(clk, new_div);
field_val = _divisor_to_clksel(clk, new_div);
if (field_val == ~0)
return -EINVAL;
v = __raw_readl(clk->clksel_reg);
v &= ~clk->clksel_mask;
v |= field_val << __ffs(clk->clksel_mask);
__raw_writel(v, clk->clksel_reg);
v = __raw_readl(clk->clksel_reg); /* OCP barrier */
_write_clksel_reg(clk, field_val);
clk->rate = clk->parent->rate / new_div;
pr_debug("clock: %s: set rate to %ld\n", clk->name, clk->rate);
return 0;
}
/*
* Clksel parent setting function - not passed in struct clk function
* pointer - instead, the OMAP clock code currently assumes that any
* parent-setting clock is a clksel clock, and calls
* omap2_clksel_set_parent() by default
*/
/**
* omap2_clksel_set_parent() - change a clock's parent clock
* @clk: struct clk * of the child clock
* @new_parent: struct clk * of the new parent clock
*
* This function is intended to be called only by the clock framework.
* Change the parent clock of clock @clk to @new_parent. This is
* intended to be used while @clk is disabled. This function does not
* currently check the usecount of the clock, so if multiple drivers
* are using the clock, and the parent is changed, they will all be
* affected without any notification. Returns -EINVAL upon error, or
* 0 upon success.
*/
int omap2_clksel_set_parent(struct clk *clk, struct clk *new_parent)
{
u32 field_val, v, parent_div;
u32 field_val = 0;
u32 parent_div;
if (!clk->clksel || !clk->clksel_mask)
return -EINVAL;
parent_div = _omap2_clksel_get_src_field(new_parent, clk, &field_val);
parent_div = _get_div_and_fieldval(new_parent, clk, &field_val);
if (!parent_div)
return -EINVAL;
/* Set new source value (previous dividers if any in effect) */
v = __raw_readl(clk->clksel_reg);
v &= ~clk->clksel_mask;
v |= field_val << __ffs(clk->clksel_mask);
__raw_writel(v, clk->clksel_reg);
v = __raw_readl(clk->clksel_reg); /* OCP barrier */
_write_clksel_reg(clk, field_val);
clk_reparent(clk, new_parent);
@ -423,7 +502,7 @@ int omap2_clksel_set_parent(struct clk *clk, struct clk *new_parent)
if (parent_div > 0)
clk->rate /= parent_div;
pr_debug("clock: set parent of %s to %s (new rate %ld)\n",
pr_debug("clock: %s: set parent to %s (new rate %ld)\n",
clk->name, clk->parent->name, clk->rate);
return 0;

9
arch/arm/mach-omap2/clock.c
View File

@ -334,6 +334,15 @@ oce_err1:
return ret;
}
/* 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)
return clk->round_rate(clk, rate);
return clk->rate;
}
/* Set the clock rate for a clock source */
int omap2_clk_set_rate(struct clk *clk, unsigned long rate)
{

11
arch/arm/mach-omap2/clock.h
View File

@ -73,19 +73,20 @@ void omap2_clk_disable_unused(struct clk *clk);
#define omap2_clk_disable_unused NULL
#endif
unsigned long omap2_clksel_recalc(struct clk *clk);
void omap2_init_clk_clkdm(struct clk *clk);
void omap2_init_clksel_parent(struct clk *clk);
u32 omap2_clksel_get_divisor(struct clk *clk);
/* clkt_clksel.c public functions */
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_init_clksel_parent(struct clk *clk);
unsigned long omap2_clksel_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);
int omap2_clksel_set_parent(struct clk *clk, struct clk *new_parent);
u32 omap2_get_dpll_rate(struct clk *clk);
void omap2_init_dpll_parent(struct clk *clk);
int omap2_wait_clock_ready(void __iomem *reg, u32 cval, const char *name);