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_aic.h>
  29 #include <mach/at91_pmc.h>
  30 #include <mach/cpu.h>
  31
  32 #include "generic.h"
  33 #include "pm.h"
  34
  35 /*
  36  * Show the reason for the previous system reset.
  37  */
  38
  39 #include <mach/at91_rstc.h>
  40 #include <mach/at91_shdwc.h>
  41
  42 static void __init show_reset_status(void)
  43 {
  44         static char reset[] __initdata = "reset";
  45
  46         static char general[] __initdata = "general";
  47         static char wakeup[] __initdata = "wakeup";
  48         static char watchdog[] __initdata = "watchdog";
  49         static char software[] __initdata = "software";
  50         static char user[] __initdata = "user";
  51         static char unknown[] __initdata = "unknown";
  52
  53         static char signal[] __initdata = "signal";
  54         static char rtc[] __initdata = "rtc";
  55         static char rtt[] __initdata = "rtt";
  56         static char restore[] __initdata = "power-restored";
  57
  58         char *reason, *r2 = reset;
  59         u32 reset_type, wake_type;
  60
  61         if (!at91_shdwc_base || !at91_rstc_base)
  62                 return;
  63
  64         reset_type = at91_rstc_read(AT91_RSTC_SR) & AT91_RSTC_RSTTYP;
  65         wake_type = at91_shdwc_read(AT91_SHDW_SR);
  66
  67         switch (reset_type) {
  68         case AT91_RSTC_RSTTYP_GENERAL:
  69                 reason = general;
  70                 break;
  71         case AT91_RSTC_RSTTYP_WAKEUP:
  72                 /* board-specific code enabled the wakeup sources */
  73                 reason = wakeup;
  74
  75                 /* "wakeup signal" */
  76                 if (wake_type & AT91_SHDW_WAKEUP0)
  77                         r2 = signal;
  78                 else {
  79                         r2 = reason;
  80                         if (wake_type & AT91_SHDW_RTTWK)        /* rtt wakeup */
  81                                 reason = rtt;
  82                         else if (wake_type & AT91_SHDW_RTCWK)   /* rtc wakeup */
  83                                 reason = rtc;
  84                         else if (wake_type == 0)        /* power-restored wakeup */
  85                                 reason = restore;
  86                         else                            /* unknown wakeup */
  87                                 reason = unknown;
  88                 }
  89                 break;
  90         case AT91_RSTC_RSTTYP_WATCHDOG:
  91                 reason = watchdog;
  92                 break;
  93         case AT91_RSTC_RSTTYP_SOFTWARE:
  94                 reason = software;
  95                 break;
  96         case AT91_RSTC_RSTTYP_USER:
  97                 reason = user;
  98                 break;
  99         default:
 100                 reason = unknown;
 101                 break;
 102         }
 103         pr_info("AT91: Starting after %s %s\n", reason, r2);
 104 }
 105
 106 static int at91_pm_valid_state(suspend_state_t state)
 107 {
 108         switch (state) {
 109                 case PM_SUSPEND_ON:
 110                 case PM_SUSPEND_STANDBY:
 111                 case PM_SUSPEND_MEM:
 112                         return 1;
 113
 114                 default:
 115                         return 0;
 116         }
 117 }
 118
 119
 120 static suspend_state_t target_state;
 121
 122 /*
 123  * Called after processes are frozen, but before we shutdown devices.
 124  */
 125 static int at91_pm_begin(suspend_state_t state)
 126 {
 127         target_state = state;
 128         return 0;
 129 }
 130
 131 /*
 132  * Verify that all the clocks are correct before entering
 133  * slow-clock mode.
 134  */
 135 static int at91_pm_verify_clocks(void)
 136 {
 137         unsigned long scsr;
 138         int i;
 139
 140         scsr = at91_pmc_read(AT91_PMC_SCSR);
 141
 142         /* USB must not be using PLLB */
 143         if (cpu_is_at91rm9200()) {
 144                 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
 145                         pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
 146                         return 0;
 147                 }
 148         } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()
 149                         || cpu_is_at91sam9g20() || cpu_is_at91sam9g10()) {
 150                 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
 151                         pr_err("AT91: PM - Suspend-to-RAM with USB still active\n");
 152                         return 0;
 153                 }
 154         }
 155
 156 #ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
 157         /* PCK0..PCK3 must be disabled, or configured to use clk32k */
 158         for (i = 0; i < 4; i++) {
 159                 u32 css;
 160
 161                 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
 162                         continue;
 163
 164                 css = at91_pmc_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
 165                 if (css != AT91_PMC_CSS_SLOW) {
 166                         pr_err("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
 167                         return 0;
 168                 }
 169         }
 170 #endif
 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         at91_gpio_suspend();
 204         at91_irq_suspend();
 205
 206         pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
 207                         /* remember all the always-wake irqs */
 208                         (at91_pmc_read(AT91_PMC_PCSR)
 209                                         | (1 << AT91_ID_FIQ)
 210                                         | (1 << AT91_ID_SYS)
 211                                         | (at91_extern_irq))
 212                                 & at91_aic_read(AT91_AIC_IMR),
 213                         state);
 214
 215         switch (state) {
 216                 /*
 217                  * Suspend-to-RAM is like STANDBY plus slow clock mode, so
 218                  * drivers must suspend more deeply:  only the master clock
 219                  * controller may be using the main oscillator.
 220                  */
 221                 case PM_SUSPEND_MEM:
 222                         /*
 223                          * Ensure that clocks are in a valid state.
 224                          */
 225                         if (!at91_pm_verify_clocks())
 226                                 goto error;
 227
 228                         /*
 229                          * Enter slow clock mode by switching over to clk32k and
 230                          * turning off the main oscillator; reverse on wakeup.
 231                          */
 232                         if (slow_clock) {
 233                                 int memctrl = AT91_MEMCTRL_SDRAMC;
 234
 235                                 if (cpu_is_at91rm9200())
 236                                         memctrl = AT91_MEMCTRL_MC;
 237                                 else if (cpu_is_at91sam9g45())
 238                                         memctrl = AT91_MEMCTRL_DDRSDR;
 239 #ifdef CONFIG_AT91_SLOW_CLOCK
 240                                 /* copy slow_clock handler to SRAM, and call it */
 241                                 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
 242 #endif
 243                                 slow_clock(at91_pmc_base, at91_ramc_base[0],
 244                                            at91_ramc_base[1], memctrl);
 245                                 break;
 246                         } else {
 247                                 pr_info("AT91: PM - no slow clock mode enabled ...\n");
 248                                 /* FALLTHROUGH leaving master clock alone */
 249                         }
 250
 251                 /*
 252                  * STANDBY mode has *all* drivers suspended; ignores irqs not
 253                  * marked as 'wakeup' event sources; and reduces DRAM power.
 254                  * But otherwise it's identical to PM_SUSPEND_ON:  cpu idle, and
 255                  * nothing fancy done with main or cpu clocks.
 256                  */
 257                 case PM_SUSPEND_STANDBY:
 258                         /*
 259                          * NOTE: the Wait-for-Interrupt instruction needs to be
 260                          * in icache so no SDRAM accesses are needed until the
 261                          * wakeup IRQ occurs and self-refresh is terminated.
 262                          * For ARM 926 based chips, this requirement is weaker
 263                          * as at91sam9 can access a RAM in self-refresh mode.
 264                          */
 265                         if (cpu_is_at91rm9200())
 266                                 at91rm9200_standby();
 267                         else if (cpu_is_at91sam9g45())
 268                                 at91sam9g45_standby();
 269                         else
 270                                 at91sam9_standby();
 271                         break;
 272
 273                 case PM_SUSPEND_ON:
 274                         cpu_do_idle();
 275                         break;
 276
 277                 default:
 278                         pr_debug("AT91: PM - bogus suspend state %d\n", state);
 279                         goto error;
 280         }
 281
 282         pr_debug("AT91: PM - wakeup %08x\n",
 283                         at91_aic_read(AT91_AIC_IPR) & at91_aic_read(AT91_AIC_IMR));
 284
 285 error:
 286         target_state = PM_SUSPEND_ON;
 287         at91_irq_resume();
 288         at91_gpio_resume();
 289         return 0;
 290 }
 291
 292 /*
 293  * Called right prior to thawing processes.
 294  */
 295 static void at91_pm_end(void)
 296 {
 297         target_state = PM_SUSPEND_ON;
 298 }
 299
 300
 301 static const struct platform_suspend_ops at91_pm_ops = {
 302         .valid  = at91_pm_valid_state,
 303         .begin  = at91_pm_begin,
 304         .enter  = at91_pm_enter,
 305         .end    = at91_pm_end,
 306 };
 307
 308 static int __init at91_pm_init(void)
 309 {
 310 #ifdef CONFIG_AT91_SLOW_CLOCK
 311         slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
 312 #endif
 313
 314         pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
 315
 316         /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
 317         if (cpu_is_at91rm9200())
 318                 at91_ramc_write(0, AT91RM9200_SDRAMC_LPR, 0);
 319
 320         suspend_set_ops(&at91_pm_ops);
 321
 322         show_reset_status();
 323         return 0;
 324 }
 325 arch_initcall(at91_pm_init);