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/at91rm9200_mc.h>
  30 #include <asm/arch/gpio.h>
  31 #include <asm/arch/cpu.h>
  32
  33 #include "generic.h"
  34
  35
  36 static int at91_pm_valid_state(suspend_state_t state)
  37 {
  38         switch (state) {
  39                 case PM_SUSPEND_ON:
  40                 case PM_SUSPEND_STANDBY:
  41                 case PM_SUSPEND_MEM:
  42                         return 1;
  43
  44                 default:
  45                         return 0;
  46         }
  47 }
  48
  49
  50 static suspend_state_t target_state;
  51
  52 /*
  53  * Called after processes are frozen, but before we shutdown devices.
  54  */
  55 static int at91_pm_begin(suspend_state_t state)
  56 {
  57         target_state = state;
  58         return 0;
  59 }
  60
  61 /*
  62  * Verify that all the clocks are correct before entering
  63  * slow-clock mode.
  64  */
  65 static int at91_pm_verify_clocks(void)
  66 {
  67         unsigned long scsr;
  68         int i;
  69
  70         scsr = at91_sys_read(AT91_PMC_SCSR);
  71
  72         /* USB must not be using PLLB */
  73         if (cpu_is_at91rm9200()) {
  74                 if ((scsr & (AT91RM9200_PMC_UHP | AT91RM9200_PMC_UDP)) != 0) {
  75                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
  76                         return 0;
  77                 }
  78         } else if (cpu_is_at91sam9260() || cpu_is_at91sam9261() || cpu_is_at91sam9263()) {
  79                 if ((scsr & (AT91SAM926x_PMC_UHP | AT91SAM926x_PMC_UDP)) != 0) {
  80                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
  81                         return 0;
  82                 }
  83         } else if (cpu_is_at91cap9()) {
  84                 if ((scsr & AT91CAP9_PMC_UHP) != 0) {
  85                         pr_debug("AT91: PM - Suspend-to-RAM with USB still active\n");
  86                         return 0;
  87                 }
  88         }
  89
  90 #ifdef CONFIG_AT91_PROGRAMMABLE_CLOCKS
  91         /* PCK0..PCK3 must be disabled, or configured to use clk32k */
  92         for (i = 0; i < 4; i++) {
  93                 u32 css;
  94
  95                 if ((scsr & (AT91_PMC_PCK0 << i)) == 0)
  96                         continue;
  97
  98                 css = at91_sys_read(AT91_PMC_PCKR(i)) & AT91_PMC_CSS;
  99                 if (css != AT91_PMC_CSS_SLOW) {
 100                         pr_debug("AT91: PM - Suspend-to-RAM with PCK%d src %d\n", i, css);
 101                         return 0;
 102                 }
 103         }
 104 #endif
 105
 106         return 1;
 107 }
 108
 109 /*
 110  * Call this from platform driver suspend() to see how deeply to suspend.
 111  * For example, some controllers (like OHCI) need one of the PLL clocks
 112  * in order to act as a wakeup source, and those are not available when
 113  * going into slow clock mode.
 114  *
 115  * REVISIT: generalize as clk_will_be_available(clk)?  Other platforms have
 116  * the very same problem (but not using at91 main_clk), and it'd be better
 117  * to add one generic API rather than lots of platform-specific ones.
 118  */
 119 int at91_suspend_entering_slow_clock(void)
 120 {
 121         return (target_state == PM_SUSPEND_MEM);
 122 }
 123 EXPORT_SYMBOL(at91_suspend_entering_slow_clock);
 124
 125
 126 static void (*slow_clock)(void);
 127
 128
 129 static int at91_pm_enter(suspend_state_t state)
 130 {
 131         at91_gpio_suspend();
 132         at91_irq_suspend();
 133
 134         pr_debug("AT91: PM - wake mask %08x, pm state %d\n",
 135                         /* remember all the always-wake irqs */
 136                         (at91_sys_read(AT91_PMC_PCSR)
 137                                         | (1 << AT91_ID_FIQ)
 138                                         | (1 << AT91_ID_SYS)
 139                                         | (at91_extern_irq))
 140                                 & at91_sys_read(AT91_AIC_IMR),
 141                         state);
 142
 143         switch (state) {
 144                 /*
 145                  * Suspend-to-RAM is like STANDBY plus slow clock mode, so
 146                  * drivers must suspend more deeply:  only the master clock
 147                  * controller may be using the main oscillator.
 148                  */
 149                 case PM_SUSPEND_MEM:
 150                         /*
 151                          * Ensure that clocks are in a valid state.
 152                          */
 153                         if (!at91_pm_verify_clocks())
 154                                 goto error;
 155
 156                         /*
 157                          * Enter slow clock mode by switching over to clk32k and
 158                          * turning off the main oscillator; reverse on wakeup.
 159                          */
 160                         if (slow_clock) {
 161                                 slow_clock();
 162                                 break;
 163                         } else {
 164                                 /* DEVELOPMENT ONLY */
 165                                 pr_info("AT91: PM - no slow clock mode yet ...\n");
 166                                 /* FALLTHROUGH leaving master clock alone */
 167                         }
 168
 169                 /*
 170                  * STANDBY mode has *all* drivers suspended; ignores irqs not
 171                  * marked as 'wakeup' event sources; and reduces DRAM power.
 172                  * But otherwise it's identical to PM_SUSPEND_ON:  cpu idle, and
 173                  * nothing fancy done with main or cpu clocks.
 174                  */
 175                 case PM_SUSPEND_STANDBY:
 176                         /*
 177                          * NOTE: the Wait-for-Interrupt instruction needs to be
 178                          * in icache so the SDRAM stays in self-refresh mode until
 179                          * the wakeup IRQ occurs.
 180                          */
 181                         asm("b 1f; .align 5; 1:");
 182                         asm("mcr p15, 0, r0, c7, c10, 4");      /* drain write buffer */
 183                         at91_sys_write(AT91_SDRAMC_SRR, 1);     /* self-refresh mode */
 184                         /* fall though to next state */
 185
 186                 case PM_SUSPEND_ON:
 187                         asm("mcr p15, 0, r0, c7, c0, 4");       /* wait for interrupt */
 188                         break;
 189
 190                 default:
 191                         pr_debug("AT91: PM - bogus suspend state %d\n", state);
 192                         goto error;
 193         }
 194
 195         pr_debug("AT91: PM - wakeup %08x\n",
 196                         at91_sys_read(AT91_AIC_IPR) & at91_sys_read(AT91_AIC_IMR));
 197
 198 error:
 199         target_state = PM_SUSPEND_ON;
 200         at91_irq_resume();
 201         at91_gpio_resume();
 202         return 0;
 203 }
 204
 205 /*
 206  * Called right prior to thawing processes.
 207  */
 208 static void at91_pm_end(void)
 209 {
 210         target_state = PM_SUSPEND_ON;
 211 }
 212
 213
 214 static struct platform_suspend_ops at91_pm_ops ={
 215         .valid  = at91_pm_valid_state,
 216         .begin  = at91_pm_begin,
 217         .enter  = at91_pm_enter,
 218         .end    = at91_pm_end,
 219 };
 220
 221 static int __init at91_pm_init(void)
 222 {
 223         printk("AT91: Power Management\n");
 224
 225 #ifdef CONFIG_AT91_PM_SLOW_CLOCK
 226         /* REVISIT allocations of SRAM should be dynamically managed.
 227          * FIQ handlers and other components will want SRAM/TCM too...
 228          */
 229         slow_clock = (void *) (AT91_VA_BASE_SRAM + (3 * SZ_4K));
 230         memcpy(slow_clock, at91rm9200_slow_clock, at91rm9200_slow_clock_sz);
 231 #endif
 232
 233         /* Disable SDRAM low-power mode.  Cannot be used with self-refresh. */
 234         at91_sys_write(AT91_SDRAMC_LPR, 0);
 235
 236         suspend_set_ops(&at91_pm_ops);
 237
 238         return 0;
 239 }
 240 arch_initcall(at91_pm_init);