arch/avr32/mach-at32ap/pm.c

   1 /*
   2  * AVR32 AP Power Management
   3  *
   4  * Copyright (C) 2008 Atmel Corporation
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * version 2 as published by the Free Software Foundation.
   9  */
  10 #include <linux/io.h>
  11 #include <linux/suspend.h>
  12 #include <linux/vmalloc.h>
  13
  14 #include <asm/cacheflush.h>
  15 #include <asm/sysreg.h>
  16
  17 #include <mach/pm.h>
  18 #include <mach/sram.h>
  19
  20 /* FIXME: This is only valid for AP7000 */
  21 #define SDRAMC_BASE     0xfff03800
  22
  23 #include "sdramc.h"
  24
  25 #define SRAM_PAGE_FLAGS (SYSREG_BIT(TLBELO_D) | SYSREG_BF(SZ, 1)        \
  26                                 | SYSREG_BF(AP, 3) | SYSREG_BIT(G))
  27
  28
  29 static unsigned long    pm_sram_start;
  30 static size_t           pm_sram_size;
  31 static struct vm_struct *pm_sram_area;
  32
  33 static void (*avr32_pm_enter_standby)(unsigned long sdramc_base);
  34 static void (*avr32_pm_enter_str)(unsigned long sdramc_base);
  35
  36 /*
  37  * Must be called with interrupts disabled. Exceptions will be masked
  38  * on return (i.e. all exceptions will be "unrecoverable".)
  39  */
  40 static void *avr32_pm_map_sram(void)
  41 {
  42         unsigned long   vaddr;
  43         unsigned long   page_addr;
  44         u32             tlbehi;
  45         u32             mmucr;
  46
  47         vaddr = (unsigned long)pm_sram_area->addr;
  48         page_addr = pm_sram_start & PAGE_MASK;
  49
  50         /*
  51          * Mask exceptions and grab the first TLB entry. We won't be
  52          * needing it while sleeping.
  53          */
  54         asm volatile("ssrf      %0" : : "i"(SYSREG_EM_OFFSET) : "memory");
  55
  56         mmucr = sysreg_read(MMUCR);
  57         tlbehi = sysreg_read(TLBEHI);
  58         sysreg_write(MMUCR, SYSREG_BFINS(DRP, 0, mmucr));
  59
  60         tlbehi = SYSREG_BF(ASID, SYSREG_BFEXT(ASID, tlbehi));
  61         tlbehi |= vaddr & PAGE_MASK;
  62         tlbehi |= SYSREG_BIT(TLBEHI_V);
  63
  64         sysreg_write(TLBELO, page_addr | SRAM_PAGE_FLAGS);
  65         sysreg_write(TLBEHI, tlbehi);
  66         __builtin_tlbw();
  67
  68         return (void *)(vaddr + pm_sram_start - page_addr);
  69 }
  70
  71 /*
  72  * Must be called with interrupts disabled. Exceptions will be
  73  * unmasked on return.
  74  */
  75 static void avr32_pm_unmap_sram(void)
  76 {
  77         u32     mmucr;
  78         u32     tlbehi;
  79         u32     tlbarlo;
  80
  81         /* Going to update TLB entry at index 0 */
  82         mmucr = sysreg_read(MMUCR);
  83         tlbehi = sysreg_read(TLBEHI);
  84         sysreg_write(MMUCR, SYSREG_BFINS(DRP, 0, mmucr));
  85
  86         /* Clear the "valid" bit */
  87         tlbehi = SYSREG_BF(ASID, SYSREG_BFEXT(ASID, tlbehi));
  88         sysreg_write(TLBEHI, tlbehi);
  89
  90         /* Mark it as "not accessed" */
  91         tlbarlo = sysreg_read(TLBARLO);
  92         sysreg_write(TLBARLO, tlbarlo | 0x80000000U);
  93
  94         /* Update the TLB */
  95         __builtin_tlbw();
  96
  97         /* Unmask exceptions */
  98         asm volatile("csrf      %0" : : "i"(SYSREG_EM_OFFSET) : "memory");
  99 }
 100
 101 static int avr32_pm_valid_state(suspend_state_t state)
 102 {
 103         switch (state) {
 104         case PM_SUSPEND_ON:
 105         case PM_SUSPEND_STANDBY:
 106         case PM_SUSPEND_MEM:
 107                 return 1;
 108
 109         default:
 110                 return 0;
 111         }
 112 }
 113
 114 static int avr32_pm_enter(suspend_state_t state)
 115 {
 116         u32             lpr_saved;
 117         u32             evba_saved;
 118         void            *sram;
 119
 120         switch (state) {
 121         case PM_SUSPEND_STANDBY:
 122                 sram = avr32_pm_map_sram();
 123
 124                 /* Switch to in-sram exception handlers */
 125                 evba_saved = sysreg_read(EVBA);
 126                 sysreg_write(EVBA, (unsigned long)sram);
 127
 128                 /*
 129                  * Save the LPR register so that we can re-enable
 130                  * SDRAM Low Power mode on resume.
 131                  */
 132                 lpr_saved = sdramc_readl(LPR);
 133                 pr_debug("%s: Entering standby...\n", __func__);
 134                 avr32_pm_enter_standby(SDRAMC_BASE);
 135                 sdramc_writel(LPR, lpr_saved);
 136
 137                 /* Switch back to regular exception handlers */
 138                 sysreg_write(EVBA, evba_saved);
 139
 140                 avr32_pm_unmap_sram();
 141                 break;
 142
 143         case PM_SUSPEND_MEM:
 144                 sram = avr32_pm_map_sram();
 145
 146                 /* Switch to in-sram exception handlers */
 147                 evba_saved = sysreg_read(EVBA);
 148                 sysreg_write(EVBA, (unsigned long)sram);
 149
 150                 /*
 151                  * Save the LPR register so that we can re-enable
 152                  * SDRAM Low Power mode on resume.
 153                  */
 154                 lpr_saved = sdramc_readl(LPR);
 155                 pr_debug("%s: Entering suspend-to-ram...\n", __func__);
 156                 avr32_pm_enter_str(SDRAMC_BASE);
 157                 sdramc_writel(LPR, lpr_saved);
 158
 159                 /* Switch back to regular exception handlers */
 160                 sysreg_write(EVBA, evba_saved);
 161
 162                 avr32_pm_unmap_sram();
 163                 break;
 164
 165         case PM_SUSPEND_ON:
 166                 pr_debug("%s: Entering idle...\n", __func__);
 167                 cpu_enter_idle();
 168                 break;
 169
 170         default:
 171                 pr_debug("%s: Invalid suspend state %d\n", __func__, state);
 172                 goto out;
 173         }
 174
 175         pr_debug("%s: wakeup\n", __func__);
 176
 177 out:
 178         return 0;
 179 }
 180
 181 static struct platform_suspend_ops avr32_pm_ops = {
 182         .valid  = avr32_pm_valid_state,
 183         .enter  = avr32_pm_enter,
 184 };
 185
 186 static unsigned long avr32_pm_offset(void *symbol)
 187 {
 188         extern u8 pm_exception[];
 189
 190         return (unsigned long)symbol - (unsigned long)pm_exception;
 191 }
 192
 193 static int __init avr32_pm_init(void)
 194 {
 195         extern u8 pm_exception[];
 196         extern u8 pm_irq0[];
 197         extern u8 pm_standby[];
 198         extern u8 pm_suspend_to_ram[];
 199         extern u8 pm_sram_end[];
 200         void *dst;
 201
 202         /*
 203          * To keep things simple, we depend on not needing more than a
 204          * single page.
 205          */
 206         pm_sram_size = avr32_pm_offset(pm_sram_end);
 207         if (pm_sram_size > PAGE_SIZE)
 208                 goto err;
 209
 210         pm_sram_start = sram_alloc(pm_sram_size);
 211         if (!pm_sram_start)
 212                 goto err_alloc_sram;
 213
 214         /* Grab a virtual area we can use later on. */
 215         pm_sram_area = get_vm_area(pm_sram_size, VM_IOREMAP);
 216         if (!pm_sram_area)
 217                 goto err_vm_area;
 218         pm_sram_area->phys_addr = pm_sram_start;
 219
 220         local_irq_disable();
 221         dst = avr32_pm_map_sram();
 222         memcpy(dst, pm_exception, pm_sram_size);
 223         flush_dcache_region(dst, pm_sram_size);
 224         invalidate_icache_region(dst, pm_sram_size);
 225         avr32_pm_unmap_sram();
 226         local_irq_enable();
 227
 228         avr32_pm_enter_standby = dst + avr32_pm_offset(pm_standby);
 229         avr32_pm_enter_str = dst + avr32_pm_offset(pm_suspend_to_ram);
 230         intc_set_suspend_handler(avr32_pm_offset(pm_irq0));
 231
 232         suspend_set_ops(&avr32_pm_ops);
 233
 234         printk("AVR32 AP Power Management enabled\n");
 235
 236         return 0;
 237
 238 err_vm_area:
 239         sram_free(pm_sram_start, pm_sram_size);
 240 err_alloc_sram:
 241 err:
 242         pr_err("AVR32 Power Management initialization failed\n");
 243         return -ENOMEM;
 244 }
 245 arch_initcall(avr32_pm_init);