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Diffstat (limited to 'Documentation/arm/Samsung-S3C24XX/Suspend.txt')
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diff --git a/Documentation/arm/Samsung-S3C24XX/Suspend.txt b/Documentation/arm/Samsung-S3C24XX/Suspend.txt deleted file mode 100644 index cb4f0c0cdf9d..000000000000 --- a/Documentation/arm/Samsung-S3C24XX/Suspend.txt +++ /dev/null @@ -1,137 +0,0 @@ - S3C24XX Suspend Support - ======================= - - -Introduction ------------- - - The S3C24XX supports a low-power suspend mode, where the SDRAM is kept - in Self-Refresh mode, and all but the essential peripheral blocks are - powered down. For more information on how this works, please look - at the relevant CPU datasheet from Samsung. - - -Requirements ------------- - - 1) A bootloader that can support the necessary resume operation - - 2) Support for at least 1 source for resume - - 3) CONFIG_PM enabled in the kernel - - 4) Any peripherals that are going to be powered down at the same - time require suspend/resume support. - - -Resuming --------- - - The S3C2410 user manual defines the process of sending the CPU to - sleep and how it resumes. The default behaviour of the Linux code - is to set the GSTATUS3 register to the physical address of the - code to resume Linux operation. - - GSTATUS4 is currently left alone by the sleep code, and is free to - use for any other purposes (for example, the EB2410ITX uses this to - save memory configuration in). - - -Machine Support ---------------- - - The machine specific functions must call the s3c_pm_init() function - to say that its bootloader is capable of resuming. This can be as - simple as adding the following to the machine's definition: - - INITMACHINE(s3c_pm_init) - - A board can do its own setup before calling s3c_pm_init, if it - needs to setup anything else for power management support. - - There is currently no support for over-riding the default method of - saving the resume address, if your board requires it, then contact - the maintainer and discuss what is required. - - Note, the original method of adding an late_initcall() is wrong, - and will end up initialising all compiled machines' pm init! - - The following is an example of code used for testing wakeup from - an falling edge on IRQ_EINT0: - - -static irqreturn_t button_irq(int irq, void *pw) -{ - return IRQ_HANDLED; -} - -statuc void __init machine_init(void) -{ - ... - - request_irq(IRQ_EINT0, button_irq, IRQF_TRIGGER_FALLING, - "button-irq-eint0", NULL); - - enable_irq_wake(IRQ_EINT0); - - s3c_pm_init(); -} - - -Debugging ---------- - - There are several important things to remember when using PM suspend: - - 1) The uart drivers will disable the clocks to the UART blocks when - suspending, which means that use of printascii() or similar direct - access to the UARTs will cause the debug to stop. - - 2) While the pm code itself will attempt to re-enable the UART clocks, - care should be taken that any external clock sources that the UARTs - rely on are still enabled at that point. - - 3) If any debugging is placed in the resume path, then it must have the - relevant clocks and peripherals setup before use (ie, bootloader). - - For example, if you transmit a character from the UART, the baud - rate and uart controls must be setup beforehand. - - -Configuration -------------- - - The S3C2410 specific configuration in `System Type` defines various - aspects of how the S3C2410 suspend and resume support is configured - - `S3C2410 PM Suspend debug` - - This option prints messages to the serial console before and after - the actual suspend, giving detailed information on what is - happening - - - `S3C2410 PM Suspend Memory CRC` - - Allows the entire memory to be checksummed before and after the - suspend to see if there has been any corruption of the contents. - - Note, the time to calculate the CRC is dependent on the CPU speed - and the size of memory. For an 64Mbyte RAM area on an 200MHz - S3C2410, this can take approximately 4 seconds to complete. - - This support requires the CRC32 function to be enabled. - - - `S3C2410 PM Suspend CRC Chunksize (KiB)` - - Defines the size of memory each CRC chunk covers. A smaller value - will mean that the CRC data block will take more memory, but will - identify any faults with better precision - - -Document Author ---------------- - -Ben Dooks, Copyright 2004 Simtec Electronics - |