linux/arch/arm/mach-at91/clock.c
Andrew Victor a95c729b74 [ARM] 4604/2: AT91: Master clock divistor on SAM9
The calculation for the Master clock divisor (MDIV) is different on the
SAM9 processors than on the AT91RM9200.

Orignal patch from Sascha Erlacher.

Also use the defined AT91_PMC_PRES instead of hard-coded bitmasks.

Signed-off-by: Andrew Victor <andrew@sanpeople.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
2007-11-26 19:40:25 +00:00

639 lines
15 KiB
C

/*
* linux/arch/arm/mach-at91/clock.c
*
* Copyright (C) 2005 David Brownell
* Copyright (C) 2005 Ivan Kokshaysky
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/fs.h>
#include <linux/debugfs.h>
#include <linux/seq_file.h>
#include <linux/list.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/delay.h>
#include <linux/clk.h>
#include <asm/semaphore.h>
#include <asm/io.h>
#include <asm/mach-types.h>
#include <asm/hardware.h>
#include <asm/arch/at91_pmc.h>
#include <asm/arch/cpu.h>
#include "clock.h"
/*
* There's a lot more which can be done with clocks, including cpufreq
* integration, slow clock mode support (for system suspend), letting
* PLLB be used at other rates (on boards that don't need USB), etc.
*/
#define clk_is_primary(x) ((x)->type & CLK_TYPE_PRIMARY)
#define clk_is_programmable(x) ((x)->type & CLK_TYPE_PROGRAMMABLE)
#define clk_is_peripheral(x) ((x)->type & CLK_TYPE_PERIPHERAL)
#define clk_is_sys(x) ((x)->type & CLK_TYPE_SYSTEM)
static LIST_HEAD(clocks);
static DEFINE_SPINLOCK(clk_lock);
static u32 at91_pllb_usb_init;
/*
* Four primary clock sources: two crystal oscillators (32K, main), and
* two PLLs. PLLA usually runs the master clock; and PLLB must run at
* 48 MHz (unless no USB function clocks are needed). The main clock and
* both PLLs are turned off to run in "slow clock mode" (system suspend).
*/
static struct clk clk32k = {
.name = "clk32k",
.rate_hz = AT91_SLOW_CLOCK,
.users = 1, /* always on */
.id = 0,
.type = CLK_TYPE_PRIMARY,
};
static struct clk main_clk = {
.name = "main",
.pmc_mask = AT91_PMC_MOSCS, /* in PMC_SR */
.id = 1,
.type = CLK_TYPE_PRIMARY,
};
static struct clk plla = {
.name = "plla",
.parent = &main_clk,
.pmc_mask = AT91_PMC_LOCKA, /* in PMC_SR */
.id = 2,
.type = CLK_TYPE_PRIMARY | CLK_TYPE_PLL,
};
static void pllb_mode(struct clk *clk, int is_on)
{
u32 value;
if (is_on) {
is_on = AT91_PMC_LOCKB;
value = at91_pllb_usb_init;
} else
value = 0;
// REVISIT: Add work-around for AT91RM9200 Errata #26 ?
at91_sys_write(AT91_CKGR_PLLBR, value);
do {
cpu_relax();
} while ((at91_sys_read(AT91_PMC_SR) & AT91_PMC_LOCKB) != is_on);
}
static struct clk pllb = {
.name = "pllb",
.parent = &main_clk,
.pmc_mask = AT91_PMC_LOCKB, /* in PMC_SR */
.mode = pllb_mode,
.id = 3,
.type = CLK_TYPE_PRIMARY | CLK_TYPE_PLL,
};
static void pmc_sys_mode(struct clk *clk, int is_on)
{
if (is_on)
at91_sys_write(AT91_PMC_SCER, clk->pmc_mask);
else
at91_sys_write(AT91_PMC_SCDR, clk->pmc_mask);
}
/* USB function clocks (PLLB must be 48 MHz) */
static struct clk udpck = {
.name = "udpck",
.parent = &pllb,
.mode = pmc_sys_mode,
};
static struct clk uhpck = {
.name = "uhpck",
.parent = &pllb,
.mode = pmc_sys_mode,
};
/*
* The master clock is divided from the CPU clock (by 1-4). It's used for
* memory, interfaces to on-chip peripherals, the AIC, and sometimes more
* (e.g baud rate generation). It's sourced from one of the primary clocks.
*/
static struct clk mck = {
.name = "mck",
.pmc_mask = AT91_PMC_MCKRDY, /* in PMC_SR */
};
static void pmc_periph_mode(struct clk *clk, int is_on)
{
if (is_on)
at91_sys_write(AT91_PMC_PCER, clk->pmc_mask);
else
at91_sys_write(AT91_PMC_PCDR, clk->pmc_mask);
}
static struct clk __init *at91_css_to_clk(unsigned long css)
{
switch (css) {
case AT91_PMC_CSS_SLOW:
return &clk32k;
case AT91_PMC_CSS_MAIN:
return &main_clk;
case AT91_PMC_CSS_PLLA:
return &plla;
case AT91_PMC_CSS_PLLB:
return &pllb;
}
return NULL;
}
/*
* Associate a particular clock with a function (eg, "uart") and device.
* The drivers can then request the same 'function' with several different
* devices and not care about which clock name to use.
*/
void __init at91_clock_associate(const char *id, struct device *dev, const char *func)
{
struct clk *clk = clk_get(NULL, id);
if (!dev || !clk || !IS_ERR(clk_get(dev, func)))
return;
clk->function = func;
clk->dev = dev;
}
/* clocks cannot be de-registered no refcounting necessary */
struct clk *clk_get(struct device *dev, const char *id)
{
struct clk *clk;
list_for_each_entry(clk, &clocks, node) {
if (strcmp(id, clk->name) == 0)
return clk;
if (clk->function && (dev == clk->dev) && strcmp(id, clk->function) == 0)
return clk;
}
return ERR_PTR(-ENOENT);
}
EXPORT_SYMBOL(clk_get);
void clk_put(struct clk *clk)
{
}
EXPORT_SYMBOL(clk_put);
static void __clk_enable(struct clk *clk)
{
if (clk->parent)
__clk_enable(clk->parent);
if (clk->users++ == 0 && clk->mode)
clk->mode(clk, 1);
}
int clk_enable(struct clk *clk)
{
unsigned long flags;
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)
{
BUG_ON(clk->users == 0);
if (--clk->users == 0 && clk->mode)
clk->mode(clk, 0);
if (clk->parent)
__clk_disable(clk->parent);
}
void clk_disable(struct clk *clk)
{
unsigned long flags;
spin_lock_irqsave(&clk_lock, flags);
__clk_disable(clk);
spin_unlock_irqrestore(&clk_lock, flags);
}
EXPORT_SYMBOL(clk_disable);
unsigned long clk_get_rate(struct clk *clk)
{
unsigned long flags;
unsigned long rate;
spin_lock_irqsave(&clk_lock, flags);
for (;;) {
rate = clk->rate_hz;
if (rate || !clk->parent)
break;
clk = clk->parent;
}
spin_unlock_irqrestore(&clk_lock, flags);
return rate;
}
EXPORT_SYMBOL(clk_get_rate);
/*------------------------------------------------------------------------*/
#ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
/*
* For now, only the programmable clocks support reparenting (MCK could
* do this too, with care) or rate changing (the PLLs could do this too,
* ditto MCK but that's more for cpufreq). Drivers may reparent to get
* a better rate match; we don't.
*/
long clk_round_rate(struct clk *clk, unsigned long rate)
{
unsigned long flags;
unsigned prescale;
unsigned long actual;
if (!clk_is_programmable(clk))
return -EINVAL;
spin_lock_irqsave(&clk_lock, flags);
actual = clk->parent->rate_hz;
for (prescale = 0; prescale < 7; prescale++) {
if (actual && actual <= rate)
break;
actual >>= 1;
}
spin_unlock_irqrestore(&clk_lock, flags);
return (prescale < 7) ? actual : -ENOENT;
}
EXPORT_SYMBOL(clk_round_rate);
int clk_set_rate(struct clk *clk, unsigned long rate)
{
unsigned long flags;
unsigned prescale;
unsigned long actual;
if (!clk_is_programmable(clk))
return -EINVAL;
if (clk->users)
return -EBUSY;
spin_lock_irqsave(&clk_lock, flags);
actual = clk->parent->rate_hz;
for (prescale = 0; prescale < 7; prescale++) {
if (actual && actual <= rate) {
u32 pckr;
pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
pckr &= AT91_PMC_CSS_PLLB; /* clock selection */
pckr |= prescale << 2;
at91_sys_write(AT91_PMC_PCKR(clk->id), pckr);
clk->rate_hz = actual;
break;
}
actual >>= 1;
}
spin_unlock_irqrestore(&clk_lock, flags);
return (prescale < 7) ? actual : -ENOENT;
}
EXPORT_SYMBOL(clk_set_rate);
struct clk *clk_get_parent(struct clk *clk)
{
return clk->parent;
}
EXPORT_SYMBOL(clk_get_parent);
int clk_set_parent(struct clk *clk, struct clk *parent)
{
unsigned long flags;
if (clk->users)
return -EBUSY;
if (!clk_is_primary(parent) || !clk_is_programmable(clk))
return -EINVAL;
spin_lock_irqsave(&clk_lock, flags);
clk->rate_hz = parent->rate_hz;
clk->parent = parent;
at91_sys_write(AT91_PMC_PCKR(clk->id), parent->id);
spin_unlock_irqrestore(&clk_lock, flags);
return 0;
}
EXPORT_SYMBOL(clk_set_parent);
/* establish PCK0..PCK3 parentage and rate */
static void init_programmable_clock(struct clk *clk)
{
struct clk *parent;
u32 pckr;
pckr = at91_sys_read(AT91_PMC_PCKR(clk->id));
parent = at91_css_to_clk(pckr & AT91_PMC_CSS);
clk->parent = parent;
clk->rate_hz = parent->rate_hz / (1 << ((pckr & AT91_PMC_PRES) >> 2));
}
#endif /* CONFIG_AT91_PROGRAMMABLE_CLOCKS */
/*------------------------------------------------------------------------*/
#ifdef CONFIG_DEBUG_FS
static int at91_clk_show(struct seq_file *s, void *unused)
{
u32 scsr, pcsr, sr;
struct clk *clk;
seq_printf(s, "SCSR = %8x\n", scsr = at91_sys_read(AT91_PMC_SCSR));
seq_printf(s, "PCSR = %8x\n", pcsr = at91_sys_read(AT91_PMC_PCSR));
seq_printf(s, "MOR = %8x\n", at91_sys_read(AT91_CKGR_MOR));
seq_printf(s, "MCFR = %8x\n", at91_sys_read(AT91_CKGR_MCFR));
seq_printf(s, "PLLA = %8x\n", at91_sys_read(AT91_CKGR_PLLAR));
seq_printf(s, "PLLB = %8x\n", at91_sys_read(AT91_CKGR_PLLBR));
seq_printf(s, "MCKR = %8x\n", at91_sys_read(AT91_PMC_MCKR));
seq_printf(s, "SR = %8x\n", sr = at91_sys_read(AT91_PMC_SR));
seq_printf(s, "\n");
list_for_each_entry(clk, &clocks, node) {
char *state;
if (clk->mode == pmc_sys_mode)
state = (scsr & clk->pmc_mask) ? "on" : "off";
else if (clk->mode == pmc_periph_mode)
state = (pcsr & clk->pmc_mask) ? "on" : "off";
else if (clk->pmc_mask)
state = (sr & clk->pmc_mask) ? "on" : "off";
else if (clk == &clk32k || clk == &main_clk)
state = "on";
else
state = "";
seq_printf(s, "%-10s users=%2d %-3s %9ld Hz %s\n",
clk->name, clk->users, state, clk_get_rate(clk),
clk->parent ? clk->parent->name : "");
}
return 0;
}
static int at91_clk_open(struct inode *inode, struct file *file)
{
return single_open(file, at91_clk_show, NULL);
}
static const struct file_operations at91_clk_operations = {
.open = at91_clk_open,
.read = seq_read,
.llseek = seq_lseek,
.release = single_release,
};
static int __init at91_clk_debugfs_init(void)
{
/* /sys/kernel/debug/at91_clk */
(void) debugfs_create_file("at91_clk", S_IFREG | S_IRUGO, NULL, NULL, &at91_clk_operations);
return 0;
}
postcore_initcall(at91_clk_debugfs_init);
#endif
/*------------------------------------------------------------------------*/
/* Register a new clock */
int __init clk_register(struct clk *clk)
{
if (clk_is_peripheral(clk)) {
clk->parent = &mck;
clk->mode = pmc_periph_mode;
list_add_tail(&clk->node, &clocks);
}
else if (clk_is_sys(clk)) {
clk->parent = &mck;
clk->mode = pmc_sys_mode;
list_add_tail(&clk->node, &clocks);
}
#ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
else if (clk_is_programmable(clk)) {
clk->mode = pmc_sys_mode;
init_programmable_clock(clk);
list_add_tail(&clk->node, &clocks);
}
#endif
return 0;
}
/*------------------------------------------------------------------------*/
static u32 __init at91_pll_rate(struct clk *pll, u32 freq, u32 reg)
{
unsigned mul, div;
div = reg & 0xff;
mul = (reg >> 16) & 0x7ff;
if (div && mul) {
freq /= div;
freq *= mul + 1;
} else
freq = 0;
return freq;
}
static u32 __init at91_usb_rate(struct clk *pll, u32 freq, u32 reg)
{
if (pll == &pllb && (reg & AT91_PMC_USB96M))
return freq / 2;
else
return freq;
}
static unsigned __init at91_pll_calc(unsigned main_freq, unsigned out_freq)
{
unsigned i, div = 0, mul = 0, diff = 1 << 30;
unsigned ret = (out_freq > 155000000) ? 0xbe00 : 0x3e00;
/* PLL output max 240 MHz (or 180 MHz per errata) */
if (out_freq > 240000000)
goto fail;
for (i = 1; i < 256; i++) {
int diff1;
unsigned input, mul1;
/*
* PLL input between 1MHz and 32MHz per spec, but lower
* frequences seem necessary in some cases so allow 100K.
*/
input = main_freq / i;
if (input < 100000)
continue;
if (input > 32000000)
continue;
mul1 = out_freq / input;
if (mul1 > 2048)
continue;
if (mul1 < 2)
goto fail;
diff1 = out_freq - input * mul1;
if (diff1 < 0)
diff1 = -diff1;
if (diff > diff1) {
diff = diff1;
div = i;
mul = mul1;
if (diff == 0)
break;
}
}
if (i == 256 && diff > (out_freq >> 5))
goto fail;
return ret | ((mul - 1) << 16) | div;
fail:
return 0;
}
static struct clk *const standard_pmc_clocks[] __initdata = {
/* four primary clocks */
&clk32k,
&main_clk,
&plla,
&pllb,
/* PLLB children (USB) */
&udpck,
&uhpck,
/* MCK */
&mck
};
int __init at91_clock_init(unsigned long main_clock)
{
unsigned tmp, freq, mckr;
int i;
/*
* When the bootloader initialized the main oscillator correctly,
* there's no problem using the cycle counter. But if it didn't,
* or when using oscillator bypass mode, we must be told the speed
* of the main clock.
*/
if (!main_clock) {
do {
tmp = at91_sys_read(AT91_CKGR_MCFR);
} while (!(tmp & AT91_PMC_MAINRDY));
main_clock = (tmp & AT91_PMC_MAINF) * (AT91_SLOW_CLOCK / 16);
}
main_clk.rate_hz = main_clock;
/* report if PLLA is more than mildly overclocked */
plla.rate_hz = at91_pll_rate(&plla, main_clock, at91_sys_read(AT91_CKGR_PLLAR));
if (plla.rate_hz > 209000000)
pr_info("Clocks: PLLA overclocked, %ld MHz\n", plla.rate_hz / 1000000);
/*
* USB clock init: choose 48 MHz PLLB value,
* disable 48MHz clock during usb peripheral suspend.
*
* REVISIT: assumes MCK doesn't derive from PLLB!
*/
at91_pllb_usb_init = at91_pll_calc(main_clock, 48000000 * 2) | AT91_PMC_USB96M;
pllb.rate_hz = at91_pll_rate(&pllb, main_clock, at91_pllb_usb_init);
if (cpu_is_at91rm9200()) {
uhpck.pmc_mask = AT91RM9200_PMC_UHP;
udpck.pmc_mask = AT91RM9200_PMC_UDP;
at91_sys_write(AT91_PMC_SCER, AT91RM9200_PMC_MCKUDP);
} else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()) {
uhpck.pmc_mask = AT91SAM926x_PMC_UHP;
udpck.pmc_mask = AT91SAM926x_PMC_UDP;
}
at91_sys_write(AT91_CKGR_PLLBR, 0);
udpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
uhpck.rate_hz = at91_usb_rate(&pllb, pllb.rate_hz, at91_pllb_usb_init);
/*
* MCK and CPU derive from one of those primary clocks.
* For now, assume this parentage won't change.
*/
mckr = at91_sys_read(AT91_PMC_MCKR);
mck.parent = at91_css_to_clk(mckr & AT91_PMC_CSS);
freq = mck.parent->rate_hz;
freq /= (1 << ((mckr & AT91_PMC_PRES) >> 2)); /* prescale */
if (cpu_is_at91rm9200())
mck.rate_hz = freq / (1 + ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
else
mck.rate_hz = freq / (1 << ((mckr & AT91_PMC_MDIV) >> 8)); /* mdiv */
/* Register the PMC's standard clocks */
for (i = 0; i < ARRAY_SIZE(standard_pmc_clocks); i++)
list_add_tail(&standard_pmc_clocks[i]->node, &clocks);
/* MCK and CPU clock are "always on" */
clk_enable(&mck);
printk("Clocks: CPU %u MHz, master %u MHz, main %u.%03u MHz\n",
freq / 1000000, (unsigned) mck.rate_hz / 1000000,
(unsigned) main_clock / 1000000,
((unsigned) main_clock % 1000000) / 1000);
return 0;
}
/*
* Several unused clocks may be active. Turn them off.
*/
static int __init at91_clock_reset(void)
{
unsigned long pcdr = 0;
unsigned long scdr = 0;
struct clk *clk;
list_for_each_entry(clk, &clocks, node) {
if (clk->users > 0)
continue;
if (clk->mode == pmc_periph_mode)
pcdr |= clk->pmc_mask;
if (clk->mode == pmc_sys_mode)
scdr |= clk->pmc_mask;
pr_debug("Clocks: disable unused %s\n", clk->name);
}
at91_sys_write(AT91_PMC_PCDR, pcdr);
at91_sys_write(AT91_PMC_SCDR, scdr);
return 0;
}
late_initcall(at91_clock_reset);