drivers/rtc/rtc-isl12057.c: add alarm support to Intersil ISL12057 RTC driver
This patch adds alarm support to Intersil ISL12057 driver. This allows to configure the chip to generate an interrupt when the alarm matches current time value. Alarm can be programmed up to one month in the future and is accurate to the second. The patch was developed to support two different configurations: systems w/ and w/o RTC chip IRQ line connected to the main CPU. The latter is the one found on current 3 kernel users of the chip for which support was initially developed (Netgear ReadyNAS 102, 104 and 2120 NAS). On those devices, the IRQ#2 pin of the chip is not connected to the SoC but to a PMIC. This allows setting an alarm, powering off the device and have it wake up when the alarm rings. To support that configuration the driver does the following: 1. it has alarm_irq_enable() function returns -ENOTTY when no IRQ is passed to the driver. 2. it marks the device as a wakeup source in all cases (whether an IRQ is passed to the driver or not) to have 'wakealarm' sysfs entry created. 3. it marks the device has not supporting UIE mode when no IRQ is passed to the driver (see the commmit message of c9f5c7e7 ) This specific configuration was tested on a ReadyNAS 102 by setting an alarm, powering off the device and see it reboot as expected when the alarm rang. The former configuration was tested on a Netgear ReadyNAS 102 after some soldering of the IRQ#2 pin of the RTC chip to a MPP line of the SoC (the one used usually handles the reset button). The test was performed using a modified .dts file reflecting this change (see below) and rtc-test.c program available in Documentation/rtc.txt. This test program ran as expected, which validates alarm supports, including interrupt support. As a side note, the ISL12057 remains in the list of trivial devices, i.e. no specific DT binding being added by this patch: i2c core automatically handles extraction of IRQ line info from .dts file. For instance, if one wants to reference the interrupt line for the alarm in its .dts file, adding interrupt and interrupt-parent properties works as expected: isl12057: isl12057@68 { compatible =3D "isil,isl12057"; interrupt-parent =3D <&gpio0>; interrupts =3D <6 IRQ_TYPE_EDGE_FALLING>; reg =3D <0x68>; }; FWIW, if someone is looking for a way to test alarm support on a system on which the chip IRQ line has the ability to boot the system (e.g. ReadyNAS 102, 104, etc): # echo 0 > /sys/class/rtc/rtc0/wakealarm # echo `date '+%s' -d '+ 1 minutes'` > /sys/class/rtc/rtc0/wakealarm # shutdown -h now With the commands above, after a minute, the system comes back to life. Signed-off-by:Arnaud Ebalard <arno@natisbad.org> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Peter Huewe <peter.huewe@infineon.com> Cc: Linus Walleij <linus.walleij@linaro.org> Cc: Thierry Reding <treding@nvidia.com> Cc: Mark Brown <broonie@kernel.org> Cc: Grant Likely <grant.likely@linaro.org> Cc: Uwe Kleine-König <uwe@kleine-koenig.org> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
parent
3fc70077
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