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