avr32: Power Management support ("standby" and "mem" modes)
Implement Standby support. In this mode, we'll suspend all drivers,
put the SDRAM in self-refresh mode and switch off the HSB bus
("frozen" mode.)
Implement Suspend-to-mem support. In this mode, we suspend all
drivers, put the SDRAM into self-refresh mode and switch off all
internal clocks except the 32 kHz oscillator ("stop" mode.)
The lowest-level suspend code runs from a small portion of SRAM
allocated at startup time. This gets rid of a small potential race
with the SDRAM where we might try to enter self-refresh mode in the
middle of an icache burst. We also relocate all interrupt and
exception handlers to SRAM during the small window when we enter and
exit the low-power modes.
We don't need to do any special tricks to start and stop the PLL. The
main clock is automatically gated by hardware until the PLL is stable.
Signed-off-by: Haavard Skinnemoen <hskinnemoen@atmel.com>
diff --git a/arch/avr32/mach-at32ap/pm.c b/arch/avr32/mach-at32ap/pm.c
new file mode 100644
index 0000000..0b76432
--- /dev/null
+++ b/arch/avr32/mach-at32ap/pm.c
@@ -0,0 +1,245 @@
+/*
+ * AVR32 AP Power Management
+ *
+ * Copyright (C) 2008 Atmel Corporation
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+#include <linux/io.h>
+#include <linux/suspend.h>
+#include <linux/vmalloc.h>
+
+#include <asm/cacheflush.h>
+#include <asm/sysreg.h>
+
+#include <asm/arch/pm.h>
+#include <asm/arch/sram.h>
+
+/* FIXME: This is only valid for AP7000 */
+#define SDRAMC_BASE 0xfff03800
+
+#include "sdramc.h"
+
+#define SRAM_PAGE_FLAGS (SYSREG_BIT(TLBELO_D) | SYSREG_BF(SZ, 1) \
+ | SYSREG_BF(AP, 3) | SYSREG_BIT(G))
+
+
+static unsigned long pm_sram_start;
+static size_t pm_sram_size;
+static struct vm_struct *pm_sram_area;
+
+static void (*avr32_pm_enter_standby)(unsigned long sdramc_base);
+static void (*avr32_pm_enter_str)(unsigned long sdramc_base);
+
+/*
+ * Must be called with interrupts disabled. Exceptions will be masked
+ * on return (i.e. all exceptions will be "unrecoverable".)
+ */
+static void *avr32_pm_map_sram(void)
+{
+ unsigned long vaddr;
+ unsigned long page_addr;
+ u32 tlbehi;
+ u32 mmucr;
+
+ vaddr = (unsigned long)pm_sram_area->addr;
+ page_addr = pm_sram_start & PAGE_MASK;
+
+ /*
+ * Mask exceptions and grab the first TLB entry. We won't be
+ * needing it while sleeping.
+ */
+ asm volatile("ssrf %0" : : "i"(SYSREG_EM_OFFSET) : "memory");
+
+ mmucr = sysreg_read(MMUCR);
+ tlbehi = sysreg_read(TLBEHI);
+ sysreg_write(MMUCR, SYSREG_BFINS(DRP, 0, mmucr));
+
+ tlbehi = SYSREG_BF(ASID, SYSREG_BFEXT(ASID, tlbehi));
+ tlbehi |= vaddr & PAGE_MASK;
+ tlbehi |= SYSREG_BIT(TLBEHI_V);
+
+ sysreg_write(TLBELO, page_addr | SRAM_PAGE_FLAGS);
+ sysreg_write(TLBEHI, tlbehi);
+ __builtin_tlbw();
+
+ return (void *)(vaddr + pm_sram_start - page_addr);
+}
+
+/*
+ * Must be called with interrupts disabled. Exceptions will be
+ * unmasked on return.
+ */
+static void avr32_pm_unmap_sram(void)
+{
+ u32 mmucr;
+ u32 tlbehi;
+ u32 tlbarlo;
+
+ /* Going to update TLB entry at index 0 */
+ mmucr = sysreg_read(MMUCR);
+ tlbehi = sysreg_read(TLBEHI);
+ sysreg_write(MMUCR, SYSREG_BFINS(DRP, 0, mmucr));
+
+ /* Clear the "valid" bit */
+ tlbehi = SYSREG_BF(ASID, SYSREG_BFEXT(ASID, tlbehi));
+ sysreg_write(TLBEHI, tlbehi);
+
+ /* Mark it as "not accessed" */
+ tlbarlo = sysreg_read(TLBARLO);
+ sysreg_write(TLBARLO, tlbarlo | 0x80000000U);
+
+ /* Update the TLB */
+ __builtin_tlbw();
+
+ /* Unmask exceptions */
+ asm volatile("csrf %0" : : "i"(SYSREG_EM_OFFSET) : "memory");
+}
+
+static int avr32_pm_valid_state(suspend_state_t state)
+{
+ switch (state) {
+ case PM_SUSPEND_ON:
+ case PM_SUSPEND_STANDBY:
+ case PM_SUSPEND_MEM:
+ return 1;
+
+ default:
+ return 0;
+ }
+}
+
+static int avr32_pm_enter(suspend_state_t state)
+{
+ u32 lpr_saved;
+ u32 evba_saved;
+ void *sram;
+
+ switch (state) {
+ case PM_SUSPEND_STANDBY:
+ sram = avr32_pm_map_sram();
+
+ /* Switch to in-sram exception handlers */
+ evba_saved = sysreg_read(EVBA);
+ sysreg_write(EVBA, (unsigned long)sram);
+
+ /*
+ * Save the LPR register so that we can re-enable
+ * SDRAM Low Power mode on resume.
+ */
+ lpr_saved = sdramc_readl(LPR);
+ pr_debug("%s: Entering standby...\n", __func__);
+ avr32_pm_enter_standby(SDRAMC_BASE);
+ sdramc_writel(LPR, lpr_saved);
+
+ /* Switch back to regular exception handlers */
+ sysreg_write(EVBA, evba_saved);
+
+ avr32_pm_unmap_sram();
+ break;
+
+ case PM_SUSPEND_MEM:
+ sram = avr32_pm_map_sram();
+
+ /* Switch to in-sram exception handlers */
+ evba_saved = sysreg_read(EVBA);
+ sysreg_write(EVBA, (unsigned long)sram);
+
+ /*
+ * Save the LPR register so that we can re-enable
+ * SDRAM Low Power mode on resume.
+ */
+ lpr_saved = sdramc_readl(LPR);
+ pr_debug("%s: Entering suspend-to-ram...\n", __func__);
+ avr32_pm_enter_str(SDRAMC_BASE);
+ sdramc_writel(LPR, lpr_saved);
+
+ /* Switch back to regular exception handlers */
+ sysreg_write(EVBA, evba_saved);
+
+ avr32_pm_unmap_sram();
+ break;
+
+ case PM_SUSPEND_ON:
+ pr_debug("%s: Entering idle...\n", __func__);
+ cpu_enter_idle();
+ break;
+
+ default:
+ pr_debug("%s: Invalid suspend state %d\n", __func__, state);
+ goto out;
+ }
+
+ pr_debug("%s: wakeup\n", __func__);
+
+out:
+ return 0;
+}
+
+static struct platform_suspend_ops avr32_pm_ops = {
+ .valid = avr32_pm_valid_state,
+ .enter = avr32_pm_enter,
+};
+
+static unsigned long avr32_pm_offset(void *symbol)
+{
+ extern u8 pm_exception[];
+
+ return (unsigned long)symbol - (unsigned long)pm_exception;
+}
+
+static int __init avr32_pm_init(void)
+{
+ extern u8 pm_exception[];
+ extern u8 pm_irq0[];
+ extern u8 pm_standby[];
+ extern u8 pm_suspend_to_ram[];
+ extern u8 pm_sram_end[];
+ void *dst;
+
+ /*
+ * To keep things simple, we depend on not needing more than a
+ * single page.
+ */
+ pm_sram_size = avr32_pm_offset(pm_sram_end);
+ if (pm_sram_size > PAGE_SIZE)
+ goto err;
+
+ pm_sram_start = sram_alloc(pm_sram_size);
+ if (!pm_sram_start)
+ goto err_alloc_sram;
+
+ /* Grab a virtual area we can use later on. */
+ pm_sram_area = get_vm_area(pm_sram_size, VM_IOREMAP);
+ if (!pm_sram_area)
+ goto err_vm_area;
+ pm_sram_area->phys_addr = pm_sram_start;
+
+ local_irq_disable();
+ dst = avr32_pm_map_sram();
+ memcpy(dst, pm_exception, pm_sram_size);
+ flush_dcache_region(dst, pm_sram_size);
+ invalidate_icache_region(dst, pm_sram_size);
+ avr32_pm_unmap_sram();
+ local_irq_enable();
+
+ avr32_pm_enter_standby = dst + avr32_pm_offset(pm_standby);
+ avr32_pm_enter_str = dst + avr32_pm_offset(pm_suspend_to_ram);
+ intc_set_suspend_handler(avr32_pm_offset(pm_irq0));
+
+ suspend_set_ops(&avr32_pm_ops);
+
+ printk("AVR32 AP Power Management enabled\n");
+
+ return 0;
+
+err_vm_area:
+ sram_free(pm_sram_start, pm_sram_size);
+err_alloc_sram:
+err:
+ pr_err("AVR32 Power Management initialization failed\n");
+ return -ENOMEM;
+}
+arch_initcall(avr32_pm_init);
