2 * arch/arm/mach-at91/pm.c
3 * AT91 Power Management
5 * Copyright (C) 2005 David Brownell
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
13 #include <linux/gpio.h>
14 #include <linux/suspend.h>
15 #include <linux/sched.h>
16 #include <linux/proc_fs.h>
17 #include <linux/interrupt.h>
18 #include <linux/sysfs.h>
19 #include <linux/module.h>
20 #include <linux/platform_device.h>
22 #include <linux/clk/at91_pmc.h>
25 #include <linux/atomic.h>
26 #include <asm/mach/time.h>
27 #include <asm/mach/irq.h>
30 #include <mach/hardware.h>
35 static void (*at91_pm_standby)(void);
37 static int at91_pm_valid_state(suspend_state_t state)
41 case PM_SUSPEND_STANDBY:
51 static suspend_state_t target_state;
54 * Called after processes are frozen, but before we shutdown devices.
56 static int at91_pm_begin(suspend_state_t state)
63 * Verify that all the clocks are correct before entering
66 static int at91_pm_verify_clocks(void)
71 scsr = at91_pmc_read(AT91_PMC_SCSR);
73 /* USB must not be using PLLB */
74 if (cpu_is_at91rm9200()) {
75 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
76 pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
79 } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()
80 || cpu_is_at91sam9g20() || cpu_is_at91sam9g10()) {
81 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
82 pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
87 /* PCK0..PCK3 must be disabled, or configured to use clk32k */
88 for (i = 0; i < 4; i++) {
91 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
94 css = at91_pmc_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
95 if (css != AT91_PMC_CSS_SLOW) {
96 pr_err("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
105 * Call this from platform driver suspend() to see how deeply to suspend.
106 * For example, some controllers (like OHCI) need one of the PLL clocks
107 * in order to act as a wakeup source, and those are not available when
108 * going into slow clock mode.
110 * REVISIT: generalize as clk_will_be_available(clk)? Other platforms have
111 * the very same problem (but not using at91 main_clk), and it'd be better
112 * to add one generic API rather than lots of platform-specific ones.
114 int at91_suspend_entering_slow_clock(void)
116 return (target_state == PM_SUSPEND_MEM);
118 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
121 static void (*slow_clock)(void __iomem *pmc, void __iomem *ramc0,
122 void __iomem *ramc1, int memctrl);
124 #ifdef CONFIG_AT91_SLOW_CLOCK
125 extern void at91_slow_clock(void __iomem *pmc, void __iomem *ramc0,
126 void __iomem *ramc1, int memctrl);
127 extern u32 at91_slow_clock_sz;
130 static int at91_pm_enter(suspend_state_t state)
132 at91_pinctrl_gpio_suspend();
136 * Suspend-to-RAM is like STANDBY plus slow clock mode, so
137 * drivers must suspend more deeply: only the master clock
138 * controller may be using the main oscillator.
142 * Ensure that clocks are in a valid state.
144 if (!at91_pm_verify_clocks())
148 * Enter slow clock mode by switching over to clk32k and
149 * turning off the main oscillator; reverse on wakeup.
152 int memctrl = AT91_MEMCTRL_SDRAMC;
154 if (cpu_is_at91rm9200())
155 memctrl = AT91_MEMCTRL_MC;
156 else if (cpu_is_at91sam9g45())
157 memctrl = AT91_MEMCTRL_DDRSDR;
158 #ifdef CONFIG_AT91_SLOW_CLOCK
159 /* copy slow_clock handler to SRAM, and call it */
160 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
162 slow_clock(at91_pmc_base, at91_ramc_base[0],
163 at91_ramc_base[1], memctrl);
166 pr_info("AT91: PM - no slow clock mode enabled ...\n");
167 /* FALLTHROUGH leaving master clock alone */
171 * STANDBY mode has *all* drivers suspended; ignores irqs not
172 * marked as 'wakeup' event sources; and reduces DRAM power.
173 * But otherwise it's identical to PM_SUSPEND_ON: cpu idle, and
174 * nothing fancy done with main or cpu clocks.
176 case PM_SUSPEND_STANDBY:
178 * NOTE: the Wait-for-Interrupt instruction needs to be
179 * in icache so no SDRAM accesses are needed until the
180 * wakeup IRQ occurs and self-refresh is terminated.
181 * For ARM 926 based chips, this requirement is weaker
182 * as at91sam9 can access a RAM in self-refresh mode.
193 pr_debug("AT91: PM - bogus suspend state %d\n", state);
198 target_state = PM_SUSPEND_ON;
200 at91_pinctrl_gpio_resume();
205 * Called right prior to thawing processes.
207 static void at91_pm_end(void)
209 target_state = PM_SUSPEND_ON;
213 static const struct platform_suspend_ops at91_pm_ops = {
214 .valid = at91_pm_valid_state,
215 .begin = at91_pm_begin,
216 .enter = at91_pm_enter,
220 static struct platform_device at91_cpuidle_device = {
221 .name = "cpuidle-at91",
224 void at91_pm_set_standby(void (*at91_standby)(void))
227 at91_cpuidle_device.dev.platform_data = at91_standby;
228 at91_pm_standby = at91_standby;
232 static int __init at91_pm_init(void)
234 #ifdef CONFIG_AT91_SLOW_CLOCK
235 slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
238 pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
240 /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
241 if (cpu_is_at91rm9200())
242 at91_ramc_write(0, AT91RM9200_SDRAMC_LPR, 0);
244 if (at91_cpuidle_device.dev.platform_data)
245 platform_device_register(&at91_cpuidle_device);
247 suspend_set_ops(&at91_pm_ops);
251 arch_initcall(at91_pm_init);