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>
24 #include <linux/atomic.h>
25 #include <asm/mach/time.h>
26 #include <asm/mach/irq.h>
28 #include <mach/at91_pmc.h>
36 * Show the reason for the previous system reset.
39 #include "at91_rstc.h"
40 #include "at91_shdwc.h"
42 static void (*at91_pm_standby)(void);
44 static void __init show_reset_status(void)
46 static char reset[] __initdata = "reset";
48 static char general[] __initdata = "general";
49 static char wakeup[] __initdata = "wakeup";
50 static char watchdog[] __initdata = "watchdog";
51 static char software[] __initdata = "software";
52 static char user[] __initdata = "user";
53 static char unknown[] __initdata = "unknown";
55 static char signal[] __initdata = "signal";
56 static char rtc[] __initdata = "rtc";
57 static char rtt[] __initdata = "rtt";
58 static char restore[] __initdata = "power-restored";
60 char *reason, *r2 = reset;
61 u32 reset_type, wake_type;
63 if (!at91_shdwc_base || !at91_rstc_base)
66 reset_type = at91_rstc_read(AT91_RSTC_SR) & AT91_RSTC_RSTTYP;
67 wake_type = at91_shdwc_read(AT91_SHDW_SR);
70 case AT91_RSTC_RSTTYP_GENERAL:
73 case AT91_RSTC_RSTTYP_WAKEUP:
74 /* board-specific code enabled the wakeup sources */
78 if (wake_type & AT91_SHDW_WAKEUP0)
82 if (wake_type & AT91_SHDW_RTTWK) /* rtt wakeup */
84 else if (wake_type & AT91_SHDW_RTCWK) /* rtc wakeup */
86 else if (wake_type == 0) /* power-restored wakeup */
88 else /* unknown wakeup */
92 case AT91_RSTC_RSTTYP_WATCHDOG:
95 case AT91_RSTC_RSTTYP_SOFTWARE:
98 case AT91_RSTC_RSTTYP_USER:
105 pr_info("AT91: Starting after %s %s\n", reason, r2);
108 static int at91_pm_valid_state(suspend_state_t state)
112 case PM_SUSPEND_STANDBY:
122 static suspend_state_t target_state;
125 * Called after processes are frozen, but before we shutdown devices.
127 static int at91_pm_begin(suspend_state_t state)
129 target_state = state;
134 * Verify that all the clocks are correct before entering
137 static int at91_pm_verify_clocks(void)
142 scsr = at91_pmc_read(AT91_PMC_SCSR);
144 /* USB must not be using PLLB */
145 if (cpu_is_at91rm9200()) {
146 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
147 pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
150 } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()
151 || cpu_is_at91sam9g20() || cpu_is_at91sam9g10()) {
152 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
153 pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
158 if (!IS_ENABLED(CONFIG_AT91_PROGRAMMABLE_CLOCKS))
161 /* PCK0..PCK3 must be disabled, or configured to use clk32k */
162 for (i = 0; i < 4; i++) {
165 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
168 css = at91_pmc_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
169 if (css != AT91_PMC_CSS_SLOW) {
170 pr_err("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
179 * Call this from platform driver suspend() to see how deeply to suspend.
180 * For example, some controllers (like OHCI) need one of the PLL clocks
181 * in order to act as a wakeup source, and those are not available when
182 * going into slow clock mode.
184 * REVISIT: generalize as clk_will_be_available(clk)? Other platforms have
185 * the very same problem (but not using at91 main_clk), and it'd be better
186 * to add one generic API rather than lots of platform-specific ones.
188 int at91_suspend_entering_slow_clock(void)
190 return (target_state == PM_SUSPEND_MEM);
192 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
195 static void (*slow_clock)(void __iomem *pmc, void __iomem *ramc0,
196 void __iomem *ramc1, int memctrl);
198 #ifdef CONFIG_AT91_SLOW_CLOCK
199 extern void at91_slow_clock(void __iomem *pmc, void __iomem *ramc0,
200 void __iomem *ramc1, int memctrl);
201 extern u32 at91_slow_clock_sz;
204 static int at91_pm_enter(suspend_state_t state)
206 if (of_have_populated_dt())
207 at91_pinctrl_gpio_suspend();
212 pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
213 /* remember all the always-wake irqs */
214 (at91_pmc_read(AT91_PMC_PCSR)
217 | (at91_get_extern_irq()))
218 & at91_aic_read(AT91_AIC_IMR),
223 * Suspend-to-RAM is like STANDBY plus slow clock mode, so
224 * drivers must suspend more deeply: only the master clock
225 * controller may be using the main oscillator.
229 * Ensure that clocks are in a valid state.
231 if (!at91_pm_verify_clocks())
235 * Enter slow clock mode by switching over to clk32k and
236 * turning off the main oscillator; reverse on wakeup.
239 int memctrl = AT91_MEMCTRL_SDRAMC;
241 if (cpu_is_at91rm9200())
242 memctrl = AT91_MEMCTRL_MC;
243 else if (cpu_is_at91sam9g45())
244 memctrl = AT91_MEMCTRL_DDRSDR;
245 #ifdef CONFIG_AT91_SLOW_CLOCK
246 /* copy slow_clock handler to SRAM, and call it */
247 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
249 slow_clock(at91_pmc_base, at91_ramc_base[0],
250 at91_ramc_base[1], memctrl);
253 pr_info("AT91: PM - no slow clock mode enabled ...\n");
254 /* FALLTHROUGH leaving master clock alone */
258 * STANDBY mode has *all* drivers suspended; ignores irqs not
259 * marked as 'wakeup' event sources; and reduces DRAM power.
260 * But otherwise it's identical to PM_SUSPEND_ON: cpu idle, and
261 * nothing fancy done with main or cpu clocks.
263 case PM_SUSPEND_STANDBY:
265 * NOTE: the Wait-for-Interrupt instruction needs to be
266 * in icache so no SDRAM accesses are needed until the
267 * wakeup IRQ occurs and self-refresh is terminated.
268 * For ARM 926 based chips, this requirement is weaker
269 * as at91sam9 can access a RAM in self-refresh mode.
280 pr_debug("AT91: PM - bogus suspend state %d\n", state);
284 pr_debug("AT91: PM - wakeup %08x\n",
285 at91_aic_read(AT91_AIC_IPR) & at91_aic_read(AT91_AIC_IMR));
288 target_state = PM_SUSPEND_ON;
290 if (of_have_populated_dt())
291 at91_pinctrl_gpio_resume();
298 * Called right prior to thawing processes.
300 static void at91_pm_end(void)
302 target_state = PM_SUSPEND_ON;
306 static const struct platform_suspend_ops at91_pm_ops = {
307 .valid = at91_pm_valid_state,
308 .begin = at91_pm_begin,
309 .enter = at91_pm_enter,
313 static struct platform_device at91_cpuidle_device = {
314 .name = "cpuidle-at91",
317 void at91_pm_set_standby(void (*at91_standby)(void))
320 at91_cpuidle_device.dev.platform_data = at91_standby;
321 at91_pm_standby = at91_standby;
325 static int __init at91_pm_init(void)
327 #ifdef CONFIG_AT91_SLOW_CLOCK
328 slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
331 pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
333 /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
334 if (cpu_is_at91rm9200())
335 at91_ramc_write(0, AT91RM9200_SDRAMC_LPR, 0);
337 if (at91_cpuidle_device.dev.platform_data)
338 platform_device_register(&at91_cpuidle_device);
340 suspend_set_ops(&at91_pm_ops);
345 arch_initcall(at91_pm_init);