arch/arm/mach-at91/pm.c

   1 /*
   2  * arch/arm/mach-at91/pm.c
   3  * AT91 Power Management
   4  *
   5  * Copyright (C) 2005 David Brownell
   6  *
   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.
  11  */
  12
  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>
  21 #include <linux/io.h>
  22
  23 #include <asm/irq.h>
  24 #include <linux/atomic.h>
  25 #include <asm/mach/time.h>
  26 #include <asm/mach/irq.h>
  27
  28 #include <mach/at91_pmc.h>
  29 #include <mach/cpu.h>
  30
  31 #include "generic.h"
  32 #include "pm.h"
  33
  34 /*
  35  * Show the reason for the previous system reset.
  36  */
  37
  38 #include <mach/at91_rstc.h>
  39 #include <mach/at91_shdwc.h>
  40
  41 static void __init show_reset_status(void)
  42 {
  43         static char reset[] __initdata = "reset";
  44
  45         static char general[] __initdata = "general";
  46         static char wakeup[] __initdata = "wakeup";
  47         static char watchdog[] __initdata = "watchdog";
  48         static char software[] __initdata = "software";
  49         static char user[] __initdata = "user";
  50         static char unknown[] __initdata = "unknown";
  51
  52         static char signal[] __initdata = "signal";
  53         static char rtc[] __initdata = "rtc";
  54         static char rtt[] __initdata = "rtt";
  55         static char restore[] __initdata = "power-restored";
  56
  57         char *reason, *r2 = reset;
  58         u32 reset_type, wake_type;
  59
  60         if (!at91_shdwc_base || !at91_rstc_base)
  61                 return;
  62
  63         reset_type = at91_rstc_read(AT91_RSTC_SR) & AT91_RSTC_RSTTYP;
  64         wake_type = at91_shdwc_read(AT91_SHDW_SR);
  65
  66         switch (reset_type) {
  67         case AT91_RSTC_RSTTYP_GENERAL:
  68                 reason = general;
  69                 break;
  70         case AT91_RSTC_RSTTYP_WAKEUP:
  71                 /* board-specific code enabled the wakeup sources */
  72                 reason = wakeup;
  73
  74                 /* "wakeup signal" */
  75                 if (wake_type & AT91_SHDW_WAKEUP0)
  76                         r2 = signal;
  77                 else {
  78                         r2 = reason;
  79                         if (wake_type & AT91_SHDW_RTTWK)        /* rtt wakeup */
  80                                 reason = rtt;
  81                         else if (wake_type & AT91_SHDW_RTCWK)   /* rtc wakeup */
  82                                 reason = rtc;
  83                         else if (wake_type == 0)        /* power-restored wakeup */
  84                                 reason = restore;
  85                         else                            /* unknown wakeup */
  86                                 reason = unknown;
  87                 }
  88                 break;
  89         case AT91_RSTC_RSTTYP_WATCHDOG:
  90                 reason = watchdog;
  91                 break;
  92         case AT91_RSTC_RSTTYP_SOFTWARE:
  93                 reason = software;
  94                 break;
  95         case AT91_RSTC_RSTTYP_USER:
  96                 reason = user;
  97                 break;
  98         default:
  99                 reason = unknown;
 100                 break;
 101         }
 102         pr_info("AT91: Starting after %s %s\n", reason, r2);
 103 }
 104
 105 static int at91_pm_valid_state(suspend_state_t state)
 106 {
 107         switch (state) {
 108                 case PM_SUSPEND_ON:
 109                 case PM_SUSPEND_STANDBY:
 110                 case PM_SUSPEND_MEM:
 111                         return 1;
 112
 113                 default:
 114                         return 0;
 115         }
 116 }
 117
 118
 119 static suspend_state_t target_state;
 120
 121 /*
 122  * Called after processes are frozen, but before we shutdown devices.
 123  */
 124 static int at91_pm_begin(suspend_state_t state)
 125 {
 126         target_state = state;
 127         return 0;
 128 }
 129
 130 /*
 131  * Verify that all the clocks are correct before entering
 132  * slow-clock mode.
 133  */
 134 static int at91_pm_verify_clocks(void)
 135 {
 136         unsigned long scsr;
 137         int i;
 138
 139         scsr = at91_sys_read(AT91_PMC_SCSR);
 140
 141         /* USB must not be using PLLB */
 142         if (cpu_is_at91rm9200()) {
 143                 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
 144                         pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
 145                         return 0;
 146                 }
 147         } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()
 148                         || cpu_is_at91sam9g20() || cpu_is_at91sam9g10()) {
 149                 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
 150                         pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
 151                         return 0;
 152                 }
 153         }
 154
 155 #ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
 156         /* PCK0..PCK3 must be disabled, or configured to use clk32k */
 157         for (i = 0; i < 4; i++) {
 158                 u32 css;
 159
 160                 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
 161                         continue;
 162
 163                 css = at91_sys_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
 164                 if (css != AT91_PMC_CSS_SLOW) {
 165                         pr_err("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
 166                         return 0;
 167                 }
 168         }
 169 #endif
 170
 171         return 1;
 172 }
 173
 174 /*
 175  * Call this from platform driver suspend() to see how deeply to suspend.
 176  * For example, some controllers (like OHCI) need one of the PLL clocks
 177  * in order to act as a wakeup source, and those are not available when
 178  * going into slow clock mode.
 179  *
 180  * REVISIT: generalize as clk_will_be_available(clk)?  Other platforms have
 181  * the very same problem (but not using at91 main_clk), and it'd be better
 182  * to add one generic API rather than lots of platform-specific ones.
 183  */
 184 int at91_suspend_entering_slow_clock(void)
 185 {
 186         return (target_state == PM_SUSPEND_MEM);
 187 }
 188 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
 189
 190
 191 static void (*slow_clock)(void);
 192
 193 #ifdef CONFIG_AT91_SLOW_CLOCK
 194 extern void at91_slow_clock(void);
 195 extern u32 at91_slow_clock_sz;
 196 #endif
 197
 198
 199 static int at91_pm_enter(suspend_state_t state)
 200 {
 201         at91_gpio_suspend();
 202         at91_irq_suspend();
 203
 204         pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
 205                         /* remember all the always-wake irqs */
 206                         (at91_sys_read(AT91_PMC_PCSR)
 207                                         | (1 << AT91_ID_FIQ)
 208                                         | (1 << AT91_ID_SYS)
 209                                         | (at91_extern_irq))
 210                                 & at91_aic_read(AT91_AIC_IMR),
 211                         state);
 212
 213         switch (state) {
 214                 /*
 215                  * Suspend-to-RAM is like STANDBY plus slow clock mode, so
 216                  * drivers must suspend more deeply:  only the master clock
 217                  * controller may be using the main oscillator.
 218                  */
 219                 case PM_SUSPEND_MEM:
 220                         /*
 221                          * Ensure that clocks are in a valid state.
 222                          */
 223                         if (!at91_pm_verify_clocks())
 224                                 goto error;
 225
 226                         /*
 227                          * Enter slow clock mode by switching over to clk32k and
 228                          * turning off the main oscillator; reverse on wakeup.
 229                          */
 230                         if (slow_clock) {
 231 #ifdef CONFIG_AT91_SLOW_CLOCK
 232                                 /* copy slow_clock handler to SRAM, and call it */
 233                                 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
 234 #endif
 235                                 slow_clock();
 236                                 break;
 237                         } else {
 238                                 pr_info("AT91: PM - no slow clock mode enabled ...\n");
 239                                 /* FALLTHROUGH leaving master clock alone */
 240                         }
 241
 242                 /*
 243                  * STANDBY mode has *all* drivers suspended; ignores irqs not
 244                  * marked as 'wakeup' event sources; and reduces DRAM power.
 245                  * But otherwise it's identical to PM_SUSPEND_ON:  cpu idle, and
 246                  * nothing fancy done with main or cpu clocks.
 247                  */
 248                 case PM_SUSPEND_STANDBY:
 249                         /*
 250                          * NOTE: the Wait-for-Interrupt instruction needs to be
 251                          * in icache so no SDRAM accesses are needed until the
 252                          * wakeup IRQ occurs and self-refresh is terminated.
 253                          * For ARM 926 based chips, this requirement is weaker
 254                          * as at91sam9 can access a RAM in self-refresh mode.
 255                          */
 256                         at91_standby();
 257                         break;
 258
 259                 case PM_SUSPEND_ON:
 260                         cpu_do_idle();
 261                         break;
 262
 263                 default:
 264                         pr_debug("AT91: PM - bogus suspend state %d\n", state);
 265                         goto error;
 266         }
 267
 268         pr_debug("AT91: PM - wakeup %08x\n",
 269                         at91_aic_read(AT91_AIC_IPR) & at91_aic_read(AT91_AIC_IMR));
 270
 271 error:
 272         target_state = PM_SUSPEND_ON;
 273         at91_irq_resume();
 274         at91_gpio_resume();
 275         return 0;
 276 }
 277
 278 /*
 279  * Called right prior to thawing processes.
 280  */
 281 static void at91_pm_end(void)
 282 {
 283         target_state = PM_SUSPEND_ON;
 284 }
 285
 286
 287 static const struct platform_suspend_ops at91_pm_ops = {
 288         .valid  = at91_pm_valid_state,
 289         .begin  = at91_pm_begin,
 290         .enter  = at91_pm_enter,
 291         .end    = at91_pm_end,
 292 };
 293
 294 static int __init at91_pm_init(void)
 295 {
 296 #ifdef CONFIG_AT91_SLOW_CLOCK
 297         slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
 298 #endif
 299
 300         pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
 301
 302 #ifdef CONFIG_ARCH_AT91RM9200
 303         /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
 304         at91_sys_write(AT91_SDRAMC_LPR, 0);
 305 #endif
 306
 307         suspend_set_ops(&at91_pm_ops);
 308
 309         show_reset_status();
 310         return 0;
 311 }
 312 arch_initcall(at91_pm_init);