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/suspend.h>
  14 #include <linux/sched.h>
  15 #include <linux/proc_fs.h>
  16 #include <linux/interrupt.h>
  17 #include <linux/sysfs.h>
  18 #include <linux/module.h>
  19 #include <linux/platform_device.h>
  20 #include <linux/io.h>
  21
  22 #include <asm/irq.h>
  23 #include <asm/atomic.h>
  24 #include <asm/mach/time.h>
  25 #include <asm/mach/irq.h>
  26
  27 #include <mach/at91_pmc.h>
  28 #include <mach/gpio.h>
  29 #include <mach/cpu.h>
  30
  31 #include "generic.h"
  32
  33 #ifdef CONFIG_ARCH_AT91RM9200
  34 #include <mach/at91rm9200_mc.h>
  35
  36 /*
  37  * The AT91RM9200 goes into self-refresh mode with this command, and will
  38  * terminate self-refresh automatically on the next SDRAM access.
  39  */
  40 #define sdram_selfrefresh_enable()      at91_sys_write(AT91_SDRAMC_SRR, 1)
  41 #define sdram_selfrefresh_disable()     do {} while (0)
  42
  43 #elif defined(CONFIG_ARCH_AT91CAP9)
  44 #include <mach/at91cap9_ddrsdr.h>
  45
  46 static u32 saved_lpr;
  47
  48 static inline void sdram_selfrefresh_enable(void)
  49 {
  50         u32 lpr;
  51
  52         saved_lpr = at91_sys_read(AT91_DDRSDRC_LPR);
  53
  54         lpr = saved_lpr & ~AT91_DDRSDRC_LPCB;
  55         at91_sys_write(AT91_DDRSDRC_LPR, lpr | AT91_DDRSDRC_LPCB_SELF_REFRESH);
  56 }
  57
  58 #define sdram_selfrefresh_disable()     at91_sys_write(AT91_DDRSDRC_LPR, saved_lpr)
  59
  60 #else
  61 #include <mach/at91sam9_sdramc.h>
  62
  63 #ifdef CONFIG_ARCH_AT91SAM9263
  64 /*
  65  * FIXME either or both the SDRAM controllers (EB0, EB1) might be in use;
  66  * handle those cases both here and in the Suspend-To-RAM support.
  67  */
  68 #define AT91_SDRAMC     AT91_SDRAMC0
  69 #warning Assuming EB1 SDRAM controller is *NOT* used
  70 #endif
  71
  72 static u32 saved_lpr;
  73
  74 static inline void sdram_selfrefresh_enable(void)
  75 {
  76         u32 lpr;
  77
  78         saved_lpr = at91_sys_read(AT91_SDRAMC_LPR);
  79
  80         lpr = saved_lpr & ~AT91_SDRAMC_LPCB;
  81         at91_sys_write(AT91_SDRAMC_LPR, lpr | AT91_SDRAMC_LPCB_SELF_REFRESH);
  82 }
  83
  84 #define sdram_selfrefresh_disable()     at91_sys_write(AT91_SDRAMC_LPR, saved_lpr)
  85
  86 #endif
  87
  88
  89 /*
  90  * Show the reason for the previous system reset.
  91  */
  92 #if defined(AT91_SHDWC)
  93
  94 #include <mach/at91_rstc.h>
  95 #include <mach/at91_shdwc.h>
  96
  97 static void __init show_reset_status(void)
  98 {
  99         static char reset[] __initdata = "reset";
 100
 101         static char general[] __initdata = "general";
 102         static char wakeup[] __initdata = "wakeup";
 103         static char watchdog[] __initdata = "watchdog";
 104         static char software[] __initdata = "software";
 105         static char user[] __initdata = "user";
 106         static char unknown[] __initdata = "unknown";
 107
 108         static char signal[] __initdata = "signal";
 109         static char rtc[] __initdata = "rtc";
 110         static char rtt[] __initdata = "rtt";
 111         static char restore[] __initdata = "power-restored";
 112
 113         char *reason, *r2 = reset;
 114         u32 reset_type, wake_type;
 115
 116         reset_type = at91_sys_read(AT91_RSTC_SR) & AT91_RSTC_RSTTYP;
 117         wake_type = at91_sys_read(AT91_SHDW_SR);
 118
 119         switch (reset_type) {
 120         case AT91_RSTC_RSTTYP_GENERAL:
 121                 reason = general;
 122                 break;
 123         case AT91_RSTC_RSTTYP_WAKEUP:
 124                 /* board-specific code enabled the wakeup sources */
 125                 reason = wakeup;
 126
 127                 /* "wakeup signal" */
 128                 if (wake_type & AT91_SHDW_WAKEUP0)
 129                         r2 = signal;
 130                 else {
 131                         r2 = reason;
 132                         if (wake_type & AT91_SHDW_RTTWK)        /* rtt wakeup */
 133                                 reason = rtt;
 134                         else if (wake_type & AT91_SHDW_RTCWK)   /* rtc wakeup */
 135                                 reason = rtc;
 136                         else if (wake_type == 0)        /* power-restored wakeup */
 137                                 reason = restore;
 138                         else                            /* unknown wakeup */
 139                                 reason = unknown;
 140                 }
 141                 break;
 142         case AT91_RSTC_RSTTYP_WATCHDOG:
 143                 reason = watchdog;
 144                 break;
 145         case AT91_RSTC_RSTTYP_SOFTWARE:
 146                 reason = software;
 147                 break;
 148         case AT91_RSTC_RSTTYP_USER:
 149                 reason = user;
 150                 break;
 151         default:
 152                 reason = unknown;
 153                 break;
 154         }
 155         pr_info("AT91: Starting after %s %s\n", reason, r2);
 156 }
 157 #else
 158 static void __init show_reset_status(void) {}
 159 #endif
 160
 161
 162 static int at91_pm_valid_state(suspend_state_t state)
 163 {
 164         switch (state) {
 165                 case PM_SUSPEND_ON:
 166                 case PM_SUSPEND_STANDBY:
 167                 case PM_SUSPEND_MEM:
 168                         return 1;
 169
 170                 default:
 171                         return 0;
 172         }
 173 }
 174
 175
 176 static suspend_state_t target_state;
 177
 178 /*
 179  * Called after processes are frozen, but before we shutdown devices.
 180  */
 181 static int at91_pm_begin(suspend_state_t state)
 182 {
 183         target_state = state;
 184         return 0;
 185 }
 186
 187 /*
 188  * Verify that all the clocks are correct before entering
 189  * slow-clock mode.
 190  */
 191 static int at91_pm_verify_clocks(void)
 192 {
 193         unsigned long scsr;
 194         int i;
 195
 196         scsr = at91_sys_read(AT91_PMC_SCSR);
 197
 198         /* USB must not be using PLLB */
 199         if (cpu_is_at91rm9200()) {
 200                 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
 201                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
 202                         return 0;
 203                 }
 204         } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263() || cpu_is_at91sam9g20()) {
 205                 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
 206                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
 207                         return 0;
 208                 }
 209         } else if (cpu_is_at91cap9()) {
 210                 if ((scsr & AT91CAP9_PMC_UHP) != 0) {
 211                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
 212                         return 0;
 213                 }
 214         }
 215
 216 #ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
 217         /* PCK0..PCK3 must be disabled, or configured to use clk32k */
 218         for (i = 0; i < 4; i++) {
 219                 u32 css;
 220
 221                 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
 222                         continue;
 223
 224                 css = at91_sys_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
 225                 if (css != AT91_PMC_CSS_SLOW) {
 226                         pr_debug("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
 227                         return 0;
 228                 }
 229         }
 230 #endif
 231
 232         return 1;
 233 }
 234
 235 /*
 236  * Call this from platform driver suspend() to see how deeply to suspend.
 237  * For example, some controllers (like OHCI) need one of the PLL clocks
 238  * in order to act as a wakeup source, and those are not available when
 239  * going into slow clock mode.
 240  *
 241  * REVISIT: generalize as clk_will_be_available(clk)?  Other platforms have
 242  * the very same problem (but not using at91 main_clk), and it'd be better
 243  * to add one generic API rather than lots of platform-specific ones.
 244  */
 245 int at91_suspend_entering_slow_clock(void)
 246 {
 247         return (target_state == PM_SUSPEND_MEM);
 248 }
 249 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
 250
 251
 252 static void (*slow_clock)(void);
 253
 254 #ifdef CONFIG_AT91_SLOW_CLOCK
 255 extern void at91_slow_clock(void);
 256 extern u32 at91_slow_clock_sz;
 257 #endif
 258
 259
 260 static int at91_pm_enter(suspend_state_t state)
 261 {
 262         at91_gpio_suspend();
 263         at91_irq_suspend();
 264
 265         pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
 266                         /* remember all the always-wake irqs */
 267                         (at91_sys_read(AT91_PMC_PCSR)
 268                                         | (1 << AT91_ID_FIQ)
 269                                         | (1 << AT91_ID_SYS)
 270                                         | (at91_extern_irq))
 271                                 & at91_sys_read(AT91_AIC_IMR),
 272                         state);
 273
 274         switch (state) {
 275                 /*
 276                  * Suspend-to-RAM is like STANDBY plus slow clock mode, so
 277                  * drivers must suspend more deeply:  only the master clock
 278                  * controller may be using the main oscillator.
 279                  */
 280                 case PM_SUSPEND_MEM:
 281                         /*
 282                          * Ensure that clocks are in a valid state.
 283                          */
 284                         if (!at91_pm_verify_clocks())
 285                                 goto error;
 286
 287                         /*
 288                          * Enter slow clock mode by switching over to clk32k and
 289                          * turning off the main oscillator; reverse on wakeup.
 290                          */
 291                         if (slow_clock) {
 292 #ifdef CONFIG_AT91_SLOW_CLOCK
 293                                 /* copy slow_clock handler to SRAM, and call it */
 294                                 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
 295 #endif
 296                                 slow_clock();
 297                                 break;
 298                         } else {
 299                                 pr_info("AT91: PM - no slow clock mode enabled ...\n");
 300                                 /* FALLTHROUGH leaving master clock alone */
 301                         }
 302
 303                 /*
 304                  * STANDBY mode has *all* drivers suspended; ignores irqs not
 305                  * marked as 'wakeup' event sources; and reduces DRAM power.
 306                  * But otherwise it's identical to PM_SUSPEND_ON:  cpu idle, and
 307                  * nothing fancy done with main or cpu clocks.
 308                  */
 309                 case PM_SUSPEND_STANDBY:
 310                         /*
 311                          * NOTE: the Wait-for-Interrupt instruction needs to be
 312                          * in icache so no SDRAM accesses are needed until the
 313                          * wakeup IRQ occurs and self-refresh is terminated.
 314                          */
 315                         asm("b 1f; .align 5; 1:");
 316                         asm("mcr p15, 0, r0, c7, c10, 4");      /* drain write buffer */
 317                         sdram_selfrefresh_enable();
 318                         asm("mcr p15, 0, r0, c7, c0, 4");       /* wait for interrupt */
 319                         sdram_selfrefresh_disable();
 320                         break;
 321
 322                 case PM_SUSPEND_ON:
 323                         asm("mcr p15, 0, r0, c7, c0, 4");       /* wait for interrupt */
 324                         break;
 325
 326                 default:
 327                         pr_debug("AT91: PM - bogus suspend state %d\n", state);
 328                         goto error;
 329         }
 330
 331         pr_debug("AT91: PM - wakeup %08x\n",
 332                         at91_sys_read(AT91_AIC_IPR) & at91_sys_read(AT91_AIC_IMR));
 333
 334 error:
 335         sdram_selfrefresh_disable();
 336         target_state = PM_SUSPEND_ON;
 337         at91_irq_resume();
 338         at91_gpio_resume();
 339         return 0;
 340 }
 341
 342 /*
 343  * Called right prior to thawing processes.
 344  */
 345 static void at91_pm_end(void)
 346 {
 347         target_state = PM_SUSPEND_ON;
 348 }
 349
 350
 351 static struct platform_suspend_ops at91_pm_ops ={
 352         .valid  = at91_pm_valid_state,
 353         .begin  = at91_pm_begin,
 354         .enter  = at91_pm_enter,
 355         .end    = at91_pm_end,
 356 };
 357
 358 static int __init at91_pm_init(void)
 359 {
 360 #ifdef CONFIG_AT91_SLOW_CLOCK
 361         slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
 362 #endif
 363
 364         pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
 365
 366 #ifdef CONFIG_ARCH_AT91RM9200
 367         /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
 368         at91_sys_write(AT91_SDRAMC_LPR, 0);
 369 #endif
 370
 371         suspend_set_ops(&at91_pm_ops);
 372
 373         show_reset_status();
 374         return 0;
 375 }
 376 arch_initcall(at91_pm_init);