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
  21 #include <asm/io.h>
  22 #include <asm/irq.h>
  23 #include <asm/atomic.h>
  24 #include <asm/mach/time.h>
  25 #include <asm/mach/irq.h>
  26 #include <asm/mach-types.h>
  27
  28 #include <asm/arch/at91_pmc.h>
  29 #include <asm/arch/gpio.h>
  30 #include <asm/arch/cpu.h>
  31
  32 #include "generic.h"
  33
  34 #ifdef CONFIG_ARCH_AT91RM9200
  35 #include <asm/arch/at91rm9200_mc.h>
  36
  37 /*
  38  * The AT91RM9200 goes into self-refresh mode with this command, and will
  39  * terminate self-refresh automatically on the next SDRAM access.
  40  */
  41 #define sdram_selfrefresh_enable()      at91_sys_write(AT91_SDRAMC_SRR, 1)
  42 #define sdram_selfrefresh_disable()     do {} while (0)
  43
  44 #elif defined(CONFIG_ARCH_AT91CAP9)
  45 #include <asm/arch/at91cap9_ddrsdr.h>
  46
  47 static u32 saved_lpr;
  48
  49 static inline void sdram_selfrefresh_enable(void)
  50 {
  51         u32 lpr;
  52
  53         saved_lpr = at91_sys_read(AT91_DDRSDRC_LPR);
  54
  55         lpr = saved_lpr & ~AT91_DDRSDRC_LPCB;
  56         at91_sys_write(AT91_DDRSDRC_LPR, lpr | AT91_DDRSDRC_LPCB_SELF_REFRESH);
  57 }
  58
  59 #define sdram_selfrefresh_disable()     at91_sys_write(AT91_DDRSDRC_LPR, saved_lpr)
  60
  61 #else
  62 #include <asm/arch/at91sam9_sdramc.h>
  63
  64 static u32 saved_lpr;
  65
  66 static inline void sdram_selfrefresh_enable(void)
  67 {
  68         u32 lpr;
  69
  70         saved_lpr = at91_sys_read(AT91_SDRAMC_LPR);
  71
  72         lpr = saved_lpr & ~AT91_SDRAMC_LPCB;
  73         at91_sys_write(AT91_SDRAMC_LPR, lpr | AT91_SDRAMC_LPCB_SELF_REFRESH);
  74 }
  75
  76 #define sdram_selfrefresh_disable()     at91_sys_write(AT91_SDRAMC_LPR, saved_lpr)
  77
  78 /*
  79  * FIXME: The AT91SAM9263 has a second EBI controller which may have
  80  *        additional SDRAM.  pm_slowclock.S will require a similar fix.
  81  */
  82
  83 #endif
  84
  85
  86 /*
  87  * Show the reason for the previous system reset.
  88  */
  89 #if defined(AT91_SHDWC)
  90
  91 #include <asm/arch/at91_rstc.h>
  92 #include <asm/arch/at91_shdwc.h>
  93
  94 static void __init show_reset_status(void)
  95 {
  96         static char reset[] __initdata = "reset";
  97
  98         static char general[] __initdata = "general";
  99         static char wakeup[] __initdata = "wakeup";
 100         static char watchdog[] __initdata = "watchdog";
 101         static char software[] __initdata = "software";
 102         static char user[] __initdata = "user";
 103         static char unknown[] __initdata = "unknown";
 104
 105         static char signal[] __initdata = "signal";
 106         static char rtc[] __initdata = "rtc";
 107         static char rtt[] __initdata = "rtt";
 108         static char restore[] __initdata = "power-restored";
 109
 110         char *reason, *r2 = reset;
 111         u32 reset_type, wake_type;
 112
 113         reset_type = at91_sys_read(AT91_RSTC_SR) & AT91_RSTC_RSTTYP;
 114         wake_type = at91_sys_read(AT91_SHDW_SR);
 115
 116         switch (reset_type) {
 117         case AT91_RSTC_RSTTYP_GENERAL:
 118                 reason = general;
 119                 break;
 120         case AT91_RSTC_RSTTYP_WAKEUP:
 121                 /* board-specific code enabled the wakeup sources */
 122                 reason = wakeup;
 123
 124                 /* "wakeup signal" */
 125                 if (wake_type & AT91_SHDW_WAKEUP0)
 126                         r2 = signal;
 127                 else {
 128                         r2 = reason;
 129                         if (wake_type & AT91_SHDW_RTTWK)        /* rtt wakeup */
 130                                 reason = rtt;
 131                         else if (wake_type & AT91_SHDW_RTCWK)   /* rtc wakeup */
 132                                 reason = rtc;
 133                         else if (wake_type == 0)        /* power-restored wakeup */
 134                                 reason = restore;
 135                         else                            /* unknown wakeup */
 136                                 reason = unknown;
 137                 }
 138                 break;
 139         case AT91_RSTC_RSTTYP_WATCHDOG:
 140                 reason = watchdog;
 141                 break;
 142         case AT91_RSTC_RSTTYP_SOFTWARE:
 143                 reason = software;
 144                 break;
 145         case AT91_RSTC_RSTTYP_USER:
 146                 reason = user;
 147                 break;
 148         default:
 149                 reason = unknown;
 150                 break;
 151         }
 152         pr_info("AT91: Starting after %s %s\n", reason, r2);
 153 }
 154 #else
 155 static void __init show_reset_status(void) {}
 156 #endif
 157
 158
 159 static int at91_pm_valid_state(suspend_state_t state)
 160 {
 161         switch (state) {
 162                 case PM_SUSPEND_ON:
 163                 case PM_SUSPEND_STANDBY:
 164                 case PM_SUSPEND_MEM:
 165                         return 1;
 166
 167                 default:
 168                         return 0;
 169         }
 170 }
 171
 172
 173 static suspend_state_t target_state;
 174
 175 /*
 176  * Called after processes are frozen, but before we shutdown devices.
 177  */
 178 static int at91_pm_begin(suspend_state_t state)
 179 {
 180         target_state = state;
 181         return 0;
 182 }
 183
 184 /*
 185  * Verify that all the clocks are correct before entering
 186  * slow-clock mode.
 187  */
 188 static int at91_pm_verify_clocks(void)
 189 {
 190         unsigned long scsr;
 191         int i;
 192
 193         scsr = at91_sys_read(AT91_PMC_SCSR);
 194
 195         /* USB must not be using PLLB */
 196         if (cpu_is_at91rm9200()) {
 197                 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
 198                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
 199                         return 0;
 200                 }
 201         } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()) {
 202                 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
 203                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
 204                         return 0;
 205                 }
 206         } else if (cpu_is_at91cap9()) {
 207                 if ((scsr & AT91CAP9_PMC_UHP) != 0) {
 208                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
 209                         return 0;
 210                 }
 211         }
 212
 213 #ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
 214         /* PCK0..PCK3 must be disabled, or configured to use clk32k */
 215         for (i = 0; i < 4; i++) {
 216                 u32 css;
 217
 218                 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
 219                         continue;
 220
 221                 css = at91_sys_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
 222                 if (css != AT91_PMC_CSS_SLOW) {
 223                         pr_debug("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
 224                         return 0;
 225                 }
 226         }
 227 #endif
 228
 229         return 1;
 230 }
 231
 232 /*
 233  * Call this from platform driver suspend() to see how deeply to suspend.
 234  * For example, some controllers (like OHCI) need one of the PLL clocks
 235  * in order to act as a wakeup source, and those are not available when
 236  * going into slow clock mode.
 237  *
 238  * REVISIT: generalize as clk_will_be_available(clk)?  Other platforms have
 239  * the very same problem (but not using at91 main_clk), and it'd be better
 240  * to add one generic API rather than lots of platform-specific ones.
 241  */
 242 int at91_suspend_entering_slow_clock(void)
 243 {
 244         return (target_state == PM_SUSPEND_MEM);
 245 }
 246 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
 247
 248
 249 static void (*slow_clock)(void);
 250
 251 #ifdef CONFIG_AT91_SLOW_CLOCK
 252 extern void at91_slow_clock(void);
 253 extern u32 at91_slow_clock_sz;
 254 #endif
 255
 256
 257 static int at91_pm_enter(suspend_state_t state)
 258 {
 259         at91_gpio_suspend();
 260         at91_irq_suspend();
 261
 262         pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
 263                         /* remember all the always-wake irqs */
 264                         (at91_sys_read(AT91_PMC_PCSR)
 265                                         | (1 << AT91_ID_FIQ)
 266                                         | (1 << AT91_ID_SYS)
 267                                         | (at91_extern_irq))
 268                                 & at91_sys_read(AT91_AIC_IMR),
 269                         state);
 270
 271         switch (state) {
 272                 /*
 273                  * Suspend-to-RAM is like STANDBY plus slow clock mode, so
 274                  * drivers must suspend more deeply:  only the master clock
 275                  * controller may be using the main oscillator.
 276                  */
 277                 case PM_SUSPEND_MEM:
 278                         /*
 279                          * Ensure that clocks are in a valid state.
 280                          */
 281                         if (!at91_pm_verify_clocks())
 282                                 goto error;
 283
 284                         /*
 285                          * Enter slow clock mode by switching over to clk32k and
 286                          * turning off the main oscillator; reverse on wakeup.
 287                          */
 288                         if (slow_clock) {
 289 #ifdef CONFIG_AT91_SLOW_CLOCK
 290                                 /* copy slow_clock handler to SRAM, and call it */
 291                                 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
 292 #endif
 293                                 slow_clock();
 294                                 break;
 295                         } else {
 296                                 pr_info("AT91: PM - no slow clock mode enabled ...\n");
 297                                 /* FALLTHROUGH leaving master clock alone */
 298                         }
 299
 300                 /*
 301                  * STANDBY mode has *all* drivers suspended; ignores irqs not
 302                  * marked as 'wakeup' event sources; and reduces DRAM power.
 303                  * But otherwise it's identical to PM_SUSPEND_ON:  cpu idle, and
 304                  * nothing fancy done with main or cpu clocks.
 305                  */
 306                 case PM_SUSPEND_STANDBY:
 307                         /*
 308                          * NOTE: the Wait-for-Interrupt instruction needs to be
 309                          * in icache so no SDRAM accesses are needed until the
 310                          * wakeup IRQ occurs and self-refresh is terminated.
 311                          */
 312                         asm("b 1f; .align 5; 1:");
 313                         asm("mcr p15, 0, r0, c7, c10, 4");      /* drain write buffer */
 314                         sdram_selfrefresh_enable();
 315                         asm("mcr p15, 0, r0, c7, c0, 4");       /* wait for interrupt */
 316                         sdram_selfrefresh_disable();
 317                         break;
 318
 319                 case PM_SUSPEND_ON:
 320                         asm("mcr p15, 0, r0, c7, c0, 4");       /* wait for interrupt */
 321                         break;
 322
 323                 default:
 324                         pr_debug("AT91: PM - bogus suspend state %d\n", state);
 325                         goto error;
 326         }
 327
 328         pr_debug("AT91: PM - wakeup %08x\n",
 329                         at91_sys_read(AT91_AIC_IPR) & at91_sys_read(AT91_AIC_IMR));
 330
 331 error:
 332         sdram_selfrefresh_disable();
 333         target_state = PM_SUSPEND_ON;
 334         at91_irq_resume();
 335         at91_gpio_resume();
 336         return 0;
 337 }
 338
 339 /*
 340  * Called right prior to thawing processes.
 341  */
 342 static void at91_pm_end(void)
 343 {
 344         target_state = PM_SUSPEND_ON;
 345 }
 346
 347
 348 static struct platform_suspend_ops at91_pm_ops ={
 349         .valid  = at91_pm_valid_state,
 350         .begin  = at91_pm_begin,
 351         .enter  = at91_pm_enter,
 352         .end    = at91_pm_end,
 353 };
 354
 355 static int __init at91_pm_init(void)
 356 {
 357 #ifdef CONFIG_AT91_SLOW_CLOCK
 358         slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
 359 #endif
 360
 361         pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
 362
 363 #ifdef CONFIG_ARCH_AT91RM9200
 364         /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
 365         at91_sys_write(AT91_SDRAMC_LPR, 0);
 366 #endif
 367
 368         suspend_set_ops(&at91_pm_ops);
 369
 370         show_reset_status();
 371         return 0;
 372 }
 373 arch_initcall(at91_pm_init);