From 3c0e1947d9c171649f3bde13d1010ac6d7ce09c1 Mon Sep 17 00:00:00 2001 From: Kevin Wells Date: Tue, 27 Jul 2010 08:35:56 -0700 Subject: ARM: LPC32XX: System suspend support Support for system suspend and resume Signed-off-by: Kevin Wells --- arch/arm/mach-lpc32xx/pm.c | 146 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 146 insertions(+) create mode 100644 arch/arm/mach-lpc32xx/pm.c (limited to 'arch/arm/mach-lpc32xx/pm.c') diff --git a/arch/arm/mach-lpc32xx/pm.c b/arch/arm/mach-lpc32xx/pm.c new file mode 100644 index 000000000000..a6e2aed9a49f --- /dev/null +++ b/arch/arm/mach-lpc32xx/pm.c @@ -0,0 +1,146 @@ +/* + * arch/arm/mach-lpc32xx/pm.c + * + * Original authors: Vitaly Wool, Dmitry Chigirev + * Modified by Kevin Wells + * + * 2005 (c) MontaVista Software, Inc. This file is licensed under + * the terms of the GNU General Public License version 2. This program + * is licensed "as is" without any warranty of any kind, whether express + * or implied. + */ + +/* + * LPC32XX CPU and system power management + * + * The LCP32XX has three CPU modes for controlling system power: run, + * direct-run, and halt modes. When switching between halt and run modes, + * the CPU transistions through direct-run mode. For Linux, direct-run + * mode is not used in normal operation. Halt mode is used when the + * system is fully suspended. + * + * Run mode: + * The ARM CPU clock (HCLK_PLL), HCLK bus clock, and PCLK bus clocks are + * derived from the HCLK PLL. The HCLK and PCLK bus rates are divided from + * the HCLK_PLL rate. Linux runs in this mode. + * + * Direct-run mode: + * The ARM CPU clock, HCLK bus clock, and PCLK bus clocks are driven from + * SYSCLK. SYSCLK is usually around 13MHz, but may vary based on SYSCLK + * source or the frequency of the main oscillator. In this mode, the + * HCLK_PLL can be safely enabled, changed, or disabled. + * + * Halt mode: + * SYSCLK is gated off and the CPU and system clocks are halted. + * Peripherals based on the 32KHz oscillator clock (ie, RTC, touch, + * key scanner, etc.) still operate if enabled. In this state, an enabled + * system event (ie, GPIO state change, RTC match, key press, etc.) will + * wake the system up back into direct-run mode. + * + * DRAM refresh + * DRAM clocking and refresh are slightly different for systems with DDR + * DRAM or regular SDRAM devices. If SDRAM is used in the system, the + * SDRAM will still be accessible in direct-run mode. In DDR based systems, + * a transistion to direct-run mode will stop all DDR accesses (no clocks). + * Because of this, the code to switch power modes and the code to enter + * and exit DRAM self-refresh modes must not be executed in DRAM. A small + * section of IRAM is used instead for this. + * + * Suspend is handled with the following logic: + * Backup a small area of IRAM used for the suspend code + * Copy suspend code to IRAM + * Transfer control to code in IRAM + * Places DRAMs in self-refresh mode + * Enter direct-run mode + * Save state of HCLK_PLL PLL + * Disable HCLK_PLL PLL + * Enter halt mode - CPU and buses will stop + * System enters direct-run mode when an enabled event occurs + * HCLK PLL state is restored + * Run mode is entered + * DRAMS are placed back into normal mode + * Code execution returns from IRAM + * IRAM code are used for suspend is restored + * Suspend mode is exited + */ + +#include +#include +#include + +#include + +#include +#include +#include "common.h" +#include "clock.h" + +#define TEMP_IRAM_AREA IO_ADDRESS(LPC32XX_IRAM_BASE) + +/* + * Both STANDBY and MEM suspend states are handled the same with no + * loss of CPU or memory state + */ +static int lpc32xx_pm_enter(suspend_state_t state) +{ + int (*lpc32xx_suspend_ptr) (void); + void *iram_swap_area; + + /* Allocate some space for temporary IRAM storage */ + iram_swap_area = kmalloc(lpc32xx_sys_suspend_sz, GFP_KERNEL); + if (!iram_swap_area) { + printk(KERN_ERR + "PM Suspend: cannot allocate memory to save portion " + "of SRAM\n"); + return -ENOMEM; + } + + /* Backup a small area of IRAM used for the suspend code */ + memcpy(iram_swap_area, (void *) TEMP_IRAM_AREA, + lpc32xx_sys_suspend_sz); + + /* + * Copy code to suspend system into IRAM. The suspend code + * needs to run from IRAM as DRAM may no longer be available + * when the PLL is stopped. + */ + memcpy((void *) TEMP_IRAM_AREA, &lpc32xx_sys_suspend, + lpc32xx_sys_suspend_sz); + flush_icache_range((unsigned long)TEMP_IRAM_AREA, + (unsigned long)(TEMP_IRAM_AREA) + lpc32xx_sys_suspend_sz); + + /* Transfer to suspend code in IRAM */ + lpc32xx_suspend_ptr = (void *) TEMP_IRAM_AREA; + flush_cache_all(); + (void) lpc32xx_suspend_ptr(); + + /* Restore original IRAM contents */ + memcpy((void *) TEMP_IRAM_AREA, iram_swap_area, + lpc32xx_sys_suspend_sz); + + kfree(iram_swap_area); + + return 0; +} + +static struct platform_suspend_ops lpc32xx_pm_ops = { + .valid = suspend_valid_only_mem, + .enter = lpc32xx_pm_enter, +}; + +#define EMC_DYN_MEM_CTRL_OFS 0x20 +#define EMC_SRMMC (1 << 3) +#define EMC_CTRL_REG io_p2v(LPC32XX_EMC_BASE + EMC_DYN_MEM_CTRL_OFS) +static int __init lpc32xx_pm_init(void) +{ + /* + * Setup SDRAM self-refresh clock to automatically disable o + * start of self-refresh. This only needs to be done once. + */ + __raw_writel(__raw_readl(EMC_CTRL_REG) | EMC_SRMMC, EMC_CTRL_REG); + + suspend_set_ops(&lpc32xx_pm_ops); + + return 0; +} +arch_initcall(lpc32xx_pm_init); -- cgit v1.2.3-59-g8ed1b