linux/drivers/i2c
Oleksandr Dmytryshyn 4368de19ed i2c: omap: correct usage of the interrupt enable register
We've been lucky not to have any interrupts fire during the suspend
path, otherwise we would have unpredictable behaviour in the kernel.

Based on the logic of the kernel code interrupts from i2c should be
prohibited during suspend. Kernel writes 0 to the I2C_IE register in
the omap_i2c_runtime_suspend() function. In the other side kernel
writes saved interrupt flags to the I2C_IE register in
omap_i2c_runtime_resume() function. I.e. interrupts should be disabled
during suspend.

This works for chips with version1 registers scheme. Interrupts are
disabled during suspend. For chips with version2 scheme registers
writting 0 to the I2C_IE register does nothing (because now the
I2C_IRQENABLE_SET register is located at this address). This register
is used to enable interrupts. For disabling interrupts
I2C_IRQENABLE_CLR register should be used.

Because the registers I2C_IRQENABLE_SET and I2C_IE have the same
addresses, the interrupt enabling procedure is unchanged.

I've checked that interrupts in the i2c controller are still enabled
after writting 0 to the I2C_IRQENABLE_SET register. With this patch
interrupts are disabled in the omap_i2c_runtime_suspend() function.

Patch is based on:
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tag: v3.10-rc2

Verified on OMAP4430.

Signed-off-by: Oleksandr Dmytryshyn <oleksandr.dmytryshyn@ti.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
2013-06-19 12:04:26 +02:00
..
algos Linux 3.6-rc7 2012-10-08 12:46:32 +02:00
busses i2c: omap: correct usage of the interrupt enable register 2013-06-19 12:04:26 +02:00
muxes Removal of GENERIC_GPIO for v3.10 2013-05-09 09:59:16 -07:00
i2c-boardinfo.c i2c: Update the FSF address 2012-03-26 21:47:19 +02:00
i2c-core.c Revert "i2c: core: make it possible to match a pure device tree driver" 2013-06-18 18:02:45 +02:00
i2c-core.h i2c: Update the FSF address 2012-03-26 21:47:19 +02:00
i2c-dev.c new helper: file_inode(file) 2013-02-22 23:31:31 -05:00
i2c-mux.c i2c: Make the return type of i2c_del_mux_adapter() void 2013-04-02 07:07:32 +02:00
i2c-smbus.c i2c-smbus: Convert kzalloc to devm_kzalloc 2012-10-05 22:23:52 +02:00
i2c-stub.c i2c-stub: Move to drivers/i2c 2012-10-28 21:37:00 +01:00
Kconfig drivers/i2c: remove !S390 dependency, add missing GENERIC_HARDIRQS dependencies 2013-03-11 09:59:02 +01:00
Makefile i2c-stub: Move to drivers/i2c 2012-10-28 21:37:00 +01:00