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         if (!IS_ENABLED(CONFIG_AT91_PROGRAMMABLE_CLOCKS))
 157                 return 1;
 158
 159         /* PCK0..PCK3 must be disabled, or configured to use clk32k */
 160         for (i = 0; i < 4; i++) {
 161                 u32 css;
 162
 163                 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
 164                         continue;
 165
 166                 css = at91_pmc_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
 167                 if (css != AT91_PMC_CSS_SLOW) {
 168                         pr_err("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
 169                         return 0;
 170                 }
 171         }
 172
 173         return 1;
 174 }
 175
 176 /*
 177  * Call this from platform driver suspend() to see how deeply to suspend.
 178  * For example, some controllers (like OHCI) need one of the PLL clocks
 179  * in order to act as a wakeup source, and those are not available when
 180  * going into slow clock mode.
 181  *
 182  * REVISIT: generalize as clk_will_be_available(clk)?  Other platforms have
 183  * the very same problem (but not using at91 main_clk), and it'd be better
 184  * to add one generic API rather than lots of platform-specific ones.
 185  */
 186 int at91_suspend_entering_slow_clock(void)
 187 {
 188         return (target_state == PM_SUSPEND_MEM);
 189 }
 190 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
 191
 192
 193 static void (*slow_clock)(void __iomem *pmc, void __iomem *ramc0,
 194                           void __iomem *ramc1, int memctrl);
 195
 196 #ifdef CONFIG_AT91_SLOW_CLOCK
 197 extern void at91_slow_clock(void __iomem *pmc, void __iomem *ramc0,
 198                             void __iomem *ramc1, int memctrl);
 199 extern u32 at91_slow_clock_sz;
 200 #endif
 201
 202 static int at91_pm_enter(suspend_state_t state)
 203 {
 204         at91_gpio_suspend();
 205         at91_irq_suspend();
 206
 207         pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
 208                         /* remember all the always-wake irqs */
 209                         (at91_pmc_read(AT91_PMC_PCSR)
 210                                         | (1 << AT91_ID_FIQ)
 211                                         | (1 << AT91_ID_SYS)
 212                                         | (at91_extern_irq))
 213                                 & at91_aic_read(AT91_AIC_IMR),
 214                         state);
 215
 216         switch (state) {
 217                 /*
 218                  * Suspend-to-RAM is like STANDBY plus slow clock mode, so
 219                  * drivers must suspend more deeply:  only the master clock
 220                  * controller may be using the main oscillator.
 221                  */
 222                 case PM_SUSPEND_MEM:
 223                         /*
 224                          * Ensure that clocks are in a valid state.
 225                          */
 226                         if (!at91_pm_verify_clocks())
 227                                 goto error;
 228
 229                         /*
 230                          * Enter slow clock mode by switching over to clk32k and
 231                          * turning off the main oscillator; reverse on wakeup.
 232                          */
 233                         if (slow_clock) {
 234                                 int memctrl = AT91_MEMCTRL_SDRAMC;
 235
 236                                 if (cpu_is_at91rm9200())
 237                                         memctrl = AT91_MEMCTRL_MC;
 238                                 else if (cpu_is_at91sam9g45())
 239                                         memctrl = AT91_MEMCTRL_DDRSDR;
 240 #ifdef CONFIG_AT91_SLOW_CLOCK
 241                                 /* copy slow_clock handler to SRAM, and call it */
 242                                 memcpy(slow_clock, at91_slow_clock, at91_slow_clock_sz);
 243 #endif
 244                                 slow_clock(at91_pmc_base, at91_ramc_base[0],
 245                                            at91_ramc_base[1], memctrl);
 246                                 break;
 247                         } else {
 248                                 pr_info("AT91: PM - no slow clock mode enabled ...\n");
 249                                 /* FALLTHROUGH leaving master clock alone */
 250                         }
 251
 252                 /*
 253                  * STANDBY mode has *all* drivers suspended; ignores irqs not
 254                  * marked as 'wakeup' event sources; and reduces DRAM power.
 255                  * But otherwise it's identical to PM_SUSPEND_ON:  cpu idle, and
 256                  * nothing fancy done with main or cpu clocks.
 257                  */
 258                 case PM_SUSPEND_STANDBY:
 259                         /*
 260                          * NOTE: the Wait-for-Interrupt instruction needs to be
 261                          * in icache so no SDRAM accesses are needed until the
 262                          * wakeup IRQ occurs and self-refresh is terminated.
 263                          * For ARM 926 based chips, this requirement is weaker
 264                          * as at91sam9 can access a RAM in self-refresh mode.
 265                          */
 266                         if (cpu_is_at91rm9200())
 267                                 at91rm9200_standby();
 268                         else if (cpu_is_at91sam9g45())
 269                                 at91sam9g45_standby();
 270                         else
 271                                 at91sam9_standby();
 272                         break;
 273
 274                 case PM_SUSPEND_ON:
 275                         cpu_do_idle();
 276                         break;
 277
 278                 default:
 279                         pr_debug("AT91: PM - bogus suspend state %d\n", state);
 280                         goto error;
 281         }
 282
 283         pr_debug("AT91: PM - wakeup %08x\n",
 284                         at91_aic_read(AT91_AIC_IPR) & at91_aic_read(AT91_AIC_IMR));
 285
 286 error:
 287         target_state = PM_SUSPEND_ON;
 288         at91_irq_resume();
 289         at91_gpio_resume();
 290         return 0;
 291 }
 292
 293 /*
 294  * Called right prior to thawing processes.
 295  */
 296 static void at91_pm_end(void)
 297 {
 298         target_state = PM_SUSPEND_ON;
 299 }
 300
 301
 302 static const struct platform_suspend_ops at91_pm_ops = {
 303         .valid  = at91_pm_valid_state,
 304         .begin  = at91_pm_begin,
 305         .enter  = at91_pm_enter,
 306         .end    = at91_pm_end,
 307 };
 308
 309 static int __init at91_pm_init(void)
 310 {
 311 #ifdef CONFIG_AT91_SLOW_CLOCK
 312         slow_clock = (void *) (AT91_IO_VIRT_BASE - at91_slow_clock_sz);
 313 #endif
 314
 315         pr_info("AT91: Power Management%s\n", (slow_clock ? " (with slow clock mode)" : ""));
 316
 317         /* AT91RM9200 SDRAM low-power mode cannot be used with self-refresh. */
 318         if (cpu_is_at91rm9200())
 319                 at91_ramc_write(0, AT91RM9200_SDRAMC_LPR, 0);
 320
 321         suspend_set_ops(&at91_pm_ops);
 322
 323         show_reset_status();
 324         return 0;
 325 }
 326 arch_initcall(at91_pm_init);