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 #include <linux/clk/at91_pmc.h>
  23
  24 #include <asm/irq.h>
  25 #include <linux/atomic.h>
  26 #include <asm/mach/time.h>
  27 #include <asm/mach/irq.h>
  28
  29 #include <mach/cpu.h>
  30
  31 #include "at91_aic.h"
  32 #include "generic.h"
  33 #include "pm.h"
  34
  35 /*
  36  * Show the reason for the previous system reset.
  37  */
  38
  39 #include "at91_rstc.h"
  40 #include "at91_shdwc.h"
  41
  42 static void (*at91_pm_standby)(void);
  43
  44 static void __init show_reset_status(void)
  45 {
  46         static char reset[] __initdata = "reset";
  47
  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";
  54
  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";
  59
  60         char *reason, *r2 = reset;
  61         u32 reset_type, wake_type;
  62
  63         if (!at91_shdwc_base || !at91_rstc_base)
  64                 return;
  65
  66         reset_type = at91_rstc_read(AT91_RSTC_SR) & AT91_RSTC_RSTTYP;
  67         wake_type = at91_shdwc_read(AT91_SHDW_SR);
  68
  69         switch (reset_type) {
  70         case AT91_RSTC_RSTTYP_GENERAL:
  71                 reason = general;
  72                 break;
  73         case AT91_RSTC_RSTTYP_WAKEUP:
  74                 /* board-specific code enabled the wakeup sources */
  75                 reason = wakeup;
  76
  77                 /* "wakeup signal" */
  78                 if (wake_type & AT91_SHDW_WAKEUP0)
  79                         r2 = signal;
  80                 else {
  81                         r2 = reason;
  82                         if (wake_type & AT91_SHDW_RTTWK)        /* rtt wakeup */
  83                                 reason = rtt;
  84                         else if (wake_type & AT91_SHDW_RTCWK)   /* rtc wakeup */
  85                                 reason = rtc;
  86                         else if (wake_type == 0)        /* power-restored wakeup */
  87                                 reason = restore;
  88                         else                            /* unknown wakeup */
  89                                 reason = unknown;
  90                 }
  91                 break;
  92         case AT91_RSTC_RSTTYP_WATCHDOG:
  93                 reason = watchdog;
  94                 break;
  95         case AT91_RSTC_RSTTYP_SOFTWARE:
  96                 reason = software;
  97                 break;
  98         case AT91_RSTC_RSTTYP_USER:
  99                 reason = user;
 100                 break;
 101         default:
 102                 reason = unknown;
 103                 break;
 104         }
 105         pr_info("AT91: Starting after %s %s\n", reason, r2);
 106 }
 107
 108 static int at91_pm_valid_state(suspend_state_t state)
 109 {
 110         switch (state) {
 111                 case PM_SUSPEND_ON:
 112                 case PM_SUSPEND_STANDBY:
 113                 case PM_SUSPEND_MEM:
 114                         return 1;
 115
 116                 default:
 117                         return 0;
 118         }
 119 }
 120
 121
 122 static suspend_state_t target_state;
 123
 124 /*
 125  * Called after processes are frozen, but before we shutdown devices.
 126  */
 127 static int at91_pm_begin(suspend_state_t state)
 128 {
 129         target_state = state;
 130         return 0;
 131 }
 132
 133 /*
 134  * Verify that all the clocks are correct before entering
 135  * slow-clock mode.
 136  */
 137 static int at91_pm_verify_clocks(void)
 138 {
 139         unsigned long scsr;
 140         int i;
 141
 142         scsr = at91_pmc_read(AT91_PMC_SCSR);
 143
 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");
 148                         return 0;
 149                 }
 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");
 154                         return 0;
 155                 }
 156         }
 157
 158         /* PCK0..PCK3 must be disabled, or configured to use clk32k */
 159         for (i = 0; i < 4; i++) {
 160                 u32 css;
 161
 162                 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
 163                         continue;
 164
 165                 css = at91_pmc_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
 166                 if (css != AT91_PMC_CSS_SLOW) {
 167                         pr_err("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
 168                         return 0;
 169                 }
 170         }
 171
 172         return 1;
 173 }
 174
 175 /*
 176  * Call this from platform driver suspend() to see how deeply to suspend.
 177  * For example, some controllers (like OHCI) need one of the PLL clocks
 178  * in order to act as a wakeup source, and those are not available when
 179  * going into slow clock mode.
 180  *
 181  * REVISIT: generalize as clk_will_be_available(clk)?  Other platforms have
 182  * the very same problem (but not using at91 main_clk), and it'd be better
 183  * to add one generic API rather than lots of platform-specific ones.
 184  */
 185 int at91_suspend_entering_slow_clock(void)
 186 {
 187         return (target_state == PM_SUSPEND_MEM);
 188 }
 189 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
 190
 191
 192 static void (*slow_clock)(void __iomem *pmc, void __iomem *ramc0,
 193                           void __iomem *ramc1, int memctrl);
 194
 195 #ifdef CONFIG_AT91_SLOW_CLOCK
 196 extern void at91_slow_clock(void __iomem *pmc, void __iomem *ramc0,
 197                             void __iomem *ramc1, int memctrl);
 198 extern u32 at91_slow_clock_sz;
 199 #endif
 200
 201 static int at91_pm_enter(suspend_state_t state)
 202 {
 203         if (of_have_populated_dt())
 204                 at91_pinctrl_gpio_suspend();
 205         else
 206                 at91_gpio_suspend();
 207         at91_irq_suspend();
 208
 209         pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
 210                         /* remember all the always-wake irqs */
 211                         (at91_pmc_read(AT91_PMC_PCSR)
 212                                         | (1 << AT91_ID_FIQ)
 213                                         | (1 << AT91_ID_SYS)
 214                                         | (at91_get_extern_irq()))
 215                                 & at91_aic_read(AT91_AIC_IMR),
 216                         state);
 217
 218         switch (state) {
 219                 /*
 220                  * Suspend-to-RAM is like STANDBY plus slow clock mode, so
 221                  * drivers must suspend more deeply:  only the master clock
 222                  * controller may be using the main oscillator.
 223                  */
 224                 case PM_SUSPEND_MEM:
 225                         /*
 226                          * Ensure that clocks are in a valid state.
 227                          */
 228                         if (!at91_pm_verify_clocks())
 229                                 goto error;
 230
 231                         /*
 232                          * Enter slow clock mode by switching over to clk32k and
 233                          * turning off the main oscillator; reverse on wakeup.
 234                          */
 235                         if (slow_clock) {
 236                                 int memctrl = AT91_MEMCTRL_SDRAMC;
 237
 238                                 if (cpu_is_at91rm9200())
 239                                         memctrl = AT91_MEMCTRL_MC;
 240                                 else if (cpu_is_at91sam9g45())
 241                                         memctrl = AT91_MEMCTRL_DDRSDR;
 242 #ifdef CONFIG_AT91_SLOW_CLOCK
 243                                 /* copy slow_clock handler to SRAM, and call it */
 244                                 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
 245 #endif
 246                                 slow_clock(at91_pmc_base, at91_ramc_base[0],
 247                                            at91_ramc_base[1], memctrl);
 248                                 break;
 249                         } else {
 250                                 pr_info("AT91: PM - no slow clock mode enabled ...\n");
 251                                 /* FALLTHROUGH leaving master clock alone */
 252                         }
 253
 254                 /*
 255                  * STANDBY mode has *all* drivers suspended; ignores irqs not
 256                  * marked as 'wakeup' event sources; and reduces DRAM power.
 257                  * But otherwise it's identical to PM_SUSPEND_ON:  cpu idle, and
 258                  * nothing fancy done with main or cpu clocks.
 259                  */
 260                 case PM_SUSPEND_STANDBY:
 261                         /*
 262                          * NOTE: the Wait-for-Interrupt instruction needs to be
 263                          * in icache so no SDRAM accesses are needed until the
 264                          * wakeup IRQ occurs and self-refresh is terminated.
 265                          * For ARM 926 based chips, this requirement is weaker
 266                          * as at91sam9 can access a RAM in self-refresh mode.
 267                          */
 268                         if (at91_pm_standby)
 269                                 at91_pm_standby();
 270                         break;
 271
 272                 case PM_SUSPEND_ON:
 273                         cpu_do_idle();
 274                         break;
 275
 276                 default:
 277                         pr_debug("AT91: PM - bogus suspend state %d\n", state);
 278                         goto error;
 279         }
 280
 281         pr_debug("AT91: PM - wakeup %08x\n",
 282                         at91_aic_read(AT91_AIC_IPR) & at91_aic_read(AT91_AIC_IMR));
 283
 284 error:
 285         target_state = PM_SUSPEND_ON;
 286         at91_irq_resume();
 287         if (of_have_populated_dt())
 288                 at91_pinctrl_gpio_resume();
 289         else
 290                 at91_gpio_resume();
 291         return 0;
 292 }
 293
 294 /*
 295  * Called right prior to thawing processes.
 296  */
 297 static void at91_pm_end(void)
 298 {
 299         target_state = PM_SUSPEND_ON;
 300 }
 301
 302
 303 static const struct platform_suspend_ops at91_pm_ops = {
 304         .valid  = at91_pm_valid_state,
 305         .begin  = at91_pm_begin,
 306         .enter  = at91_pm_enter,
 307         .end    = at91_pm_end,
 308 };
 309
 310 static struct platform_device at91_cpuidle_device = {
 311         .name = "cpuidle-at91",
 312 };
 313
 314 void at91_pm_set_standby(void (*at91_standby)(void))
 315 {
 316         if (at91_standby) {
 317                 at91_cpuidle_device.dev.platform_data = at91_standby;
 318                 at91_pm_standby = at91_standby;
 319         }
 320 }
 321
 322 static int __init at91_pm_init(void)
 323 {
 324 #ifdef CONFIG_AT91_SLOW_CLOCK
 325         slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
 326 #endif
 327
 328         pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
 329
 330         /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
 331         if (cpu_is_at91rm9200())
 332                 at91_ramc_write(0, AT91RM9200_SDRAMC_LPR, 0);
 333
 334         if (at91_cpuidle_device.dev.platform_data)
 335                 platform_device_register(&at91_cpuidle_device);
 336
 337         suspend_set_ops(&at91_pm_ops);
 338
 339         show_reset_status();
 340         return 0;
 341 }
 342 arch_initcall(at91_pm_init);