/*
* arch/arm/mach-at91/pm.c
* AT91 Power Management
*
* Copyright (C) 2005 David Brownell
*
* 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/suspend.h>
#include <linux/sched.h>
#include <linux/proc_fs.h>
#include <linux/interrupt.h>
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/atomic.h>
#include <asm/mach/time.h>
#include <asm/mach/irq.h>
#include <asm/mach-types.h>
#include <asm/arch/at91_pmc.h>
#include <asm/arch/at91rm9200_mc.h>
#include <asm/arch/gpio.h>
#include <asm/arch/cpu.h>
#include "generic.h"
static int at91_pm_valid_state(suspend_state_t state)
{
switch (state) {
case PM_SUSPEND_ON:
case PM_SUSPEND_STANDBY:
case PM_SUSPEND_MEM:
return 1;
default:
return 0;
}
}
static suspend_state_t target_state;
/*
* Called after processes are frozen, but before we shutdown devices.
*/
static int at91_pm_begin(suspend_state_t state)
{
target_state = state;
return 0;
}
/*
* Verify that all the clocks are correct before entering
* slow-clock mode.
*/
static int at91_pm_verify_clocks(void)
{
unsigned long scsr;
int i;
scsr = at91_sys_read(AT91_PMC_SCSR);
/* USB must not be using PLLB */
if (cpu_is_at91rm9200()) {
if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
return 0;
}
} else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()) {
if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
return 0;
}
} else if (cpu_is_at91cap9()) {
if ((scsr & AT91CAP9_PMC_UHP) != 0) {
pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
return 0;
}
}
#ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
/* PCK0..PCK3 must be disabled, or configured to use clk32k */
for (i = 0; i < 4; i++) {
u32 css;
if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
continue;
css = at91_sys_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
if (css != AT91_PMC_CSS_SLOW) {
pr_debug("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
return 0;
}
}
#endif
return 1;
}
/*
* Call this from platform driver suspend() to see how deeply to suspend.
* For example, some controllers (like OHCI) need one of the PLL clocks
* in order to act as a wakeup source, and those are not available when
* going into slow clock mode.
*
* REVISIT: generalize as clk_will_be_available(clk)? Other platforms have
* the very same problem (but not using at91 main_clk), and it'd be better
* to add one generic API rather than lots of platform-specific ones.
*/
int at91_suspend_entering_slow_clock(void)
{
return (target_state == PM_SUSPEND_MEM);
}
EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
static void (*slow_clock)(void);
static int at91_pm_enter(suspend_state_t state)
{
at91_gpio_suspend();
at91_irq_suspend();
pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
/* remember all the always-wake irqs */
(at91_sys_read(AT91_PMC_PCSR)
| (1 << AT91_ID_FIQ)
| (1 << AT91_ID_SYS)
| (at91_extern_irq))
& at91_sys_read(AT91_AIC_IMR),
state);
switch (state) {
/*
* Suspend-to-RAM is like STANDBY plus slow clock mode, so
* drivers must suspend more deeply: only the master clock
* controller may be using the main oscillator.
*/
case PM_SUSPEND_MEM:
/*
* Ensure that clocks are in a valid state.
*/
if (!at91_pm_verify_clocks())
goto error;
/*
* Enter slow clock mode by switching over to clk32k and
* turning off the main oscillator; reverse on wakeup.
*/
if (slow_clock) {
slow_clock();
break;
} else {
/* DEVELOPMENT ONLY */
pr_info("AT91: PM - no slow clock mode yet ...\n");
/* FALLTHROUGH leaving master clock alone */
}
/*
* STANDBY mode has *all* drivers suspended; ignores irqs not
* marked as 'wakeup' event sources; and reduces DRAM power.
* But otherwise it's identical to PM_SUSPEND_ON: cpu idle, and
* nothing fancy done with main or cpu clocks.
*/
case PM_SUSPEND_STANDBY:
/*
* NOTE: the Wait-for-Interrupt instruction needs to be
* in icache so the SDRAM stays in self-refresh mode until
* the wakeup IRQ occurs.
*/
asm("b 1f; .align 5; 1:");
asm("mcr p15, 0, r0, c7, c10, 4"); /* drain write buffer */
at91_sys_write(AT91_SDRAMC_SRR, 1); /* self-refresh mode */
/* fall though to next state */
case PM_SUSPEND_ON:
asm("mcr p15, 0, r0, c7, c0, 4"); /* wait for interrupt */
break;
default:
pr_debug("AT91: PM - bogus suspend state %d\n", state);
goto error;
}
pr_debug("AT91: PM - wakeup %08x\n",
at91_sys_read(AT91_AIC_IPR) & at91_sys_read(AT91_AIC_IMR));
error:
target_state = PM_SUSPEND_ON;
at91_irq_resume();
at91_gpio_resume();
return 0;
}
/*
* Called right prior to thawing processes.
*/
static void at91_pm_end(void)
{
target_state = PM_SUSPEND_ON;
}
static struct platform_suspend_ops at91_pm_ops ={
.valid = at91_pm_valid_state,
.begin = at91_pm_begin,
.enter = at91_pm_enter,
.end = at91_pm_end,
};
static int __init at91_pm_init(void)
{
printk("AT91: Power Management\n");
#ifdef CONFIG_AT91_PM_SLOW_CLOCK
/* REVISIT allocations of SRAM should be dynamically managed.
* FIQ handlers and other components will want SRAM/TCM too...
*/
slow_clock = (void *) (AT91_VA_BASE_SRAM + (3 * SZ_4K));
memcpy(slow_clock, at91rm9200_slow_clock, at91rm9200_slow_clock_sz);
#endif
/* Disable SDRAM low-power mode. Cannot be used with self-refresh. */
at91_sys_write(AT91_SDRAMC_LPR, 0);
suspend_set_ops(&at91_pm_ops);
return 0;
}
arch_initcall(at91_pm_init);
