linux/arch/arm/mach-shmobile/timer.c
Simon Horman f492b81777 ARM: shmobile: Set clock frequency in HZ from OF nodes
shmobile_init_delay() looks for OF "clock-frequency" to determine
the delay which is set by calling shmobile_setup_delay().

Unfortunately this seems to be incorrect in detail as
"clock-frequency" node values are in HZ whereas the frequency
argument to shmobile_setup_delay() is in MHz.

Provide a variant of shmobile_setup_delay() that accepts HZ to
correct this problem.

Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
2014-05-14 14:02:21 +09:00

107 lines
3.1 KiB
C

/*
* SH-Mobile Timer
*
* Copyright (C) 2010 Magnus Damm
* Copyright (C) 2002 - 2009 Paul Mundt
*
* 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; version 2 of the License.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*/
#include <linux/platform_device.h>
#include <linux/clocksource.h>
#include <linux/delay.h>
#include <linux/of_address.h>
void __init shmobile_setup_delay_hz(unsigned int max_cpu_core_hz,
unsigned int mult, unsigned int div)
{
/* calculate a worst-case loops-per-jiffy value
* based on maximum cpu core hz setting and the
* __delay() implementation in arch/arm/lib/delay.S
*
* this will result in a longer delay than expected
* when the cpu core runs on lower frequencies.
*/
unsigned int value = HZ * div / mult;
if (!preset_lpj)
preset_lpj = max_cpu_core_hz / value;
}
void __init shmobile_setup_delay(unsigned int max_cpu_core_mhz,
unsigned int mult, unsigned int div)
{
/* calculate a worst-case loops-per-jiffy value
* based on maximum cpu core mhz setting and the
* __delay() implementation in arch/arm/lib/delay.S
*
* this will result in a longer delay than expected
* when the cpu core runs on lower frequencies.
*/
unsigned int value = (1000000 * mult) / (HZ * div);
if (!preset_lpj)
preset_lpj = max_cpu_core_mhz * value;
}
void __init shmobile_init_delay(void)
{
struct device_node *np, *parent;
u32 max_freq, freq;
max_freq = 0;
parent = of_find_node_by_path("/cpus");
if (parent) {
for_each_child_of_node(parent, np) {
if (!of_property_read_u32(np, "clock-frequency", &freq))
max_freq = max(max_freq, freq);
}
of_node_put(parent);
}
if (max_freq) {
if (of_find_compatible_node(NULL, NULL, "arm,cortex-a8"))
shmobile_setup_delay_hz(max_freq, 1, 3);
else if (of_find_compatible_node(NULL, NULL, "arm,cortex-a9"))
shmobile_setup_delay_hz(max_freq, 1, 3);
else if (of_find_compatible_node(NULL, NULL, "arm,cortex-a15"))
if (!IS_ENABLED(CONFIG_ARM_ARCH_TIMER))
shmobile_setup_delay_hz(max_freq, 2, 4);
}
}
static void __init shmobile_late_time_init(void)
{
/*
* Make sure all compiled-in early timers register themselves.
*
* Run probe() for two "earlytimer" devices, these will be the
* clockevents and clocksource devices respectively. In the event
* that only a clockevents device is available, we -ENODEV on the
* clocksource and the jiffies clocksource is used transparently
* instead. No error handling is necessary here.
*/
early_platform_driver_register_all("earlytimer");
early_platform_driver_probe("earlytimer", 2, 0);
}
void __init shmobile_earlytimer_init(void)
{
late_time_init = shmobile_late_time_init;
}