On 22/04/16 22:11, Alexandre Belloni wrote: > On 22/04/2016 at 14:32:32 -0500, Rob Herring wrote : >> On Wed, Apr 20, 2016 at 01:07:49PM +0200, Jeppe Ledet-Pedersen wrote: >>> This patch adds support for the Cypress Semiconductor FM33256B processor >>> companion. The device contains a 256 kbit FRAM, an RTC, a supply voltage >>> monitor, and a watchdog timer. >>> >>> Signed-off-by: Jeppe Ledet-Pedersen <jlp@xxxxxxxxxxxx> >>> --- >>> Documentation/devicetree/bindings/mfd/fm33256b.txt | 30 ++ >>> MAINTAINERS | 6 + >>> drivers/mfd/Kconfig | 16 + >>> drivers/mfd/Makefile | 1 + >>> drivers/mfd/fm33256b.c | 488 +++++++++++++++++++++ >>> include/linux/mfd/fm33256b.h | 76 ++++ >>> 6 files changed, 617 insertions(+) >>> create mode 100644 Documentation/devicetree/bindings/mfd/fm33256b.txt >>> create mode 100644 drivers/mfd/fm33256b.c >>> create mode 100644 include/linux/mfd/fm33256b.h >>> >>> diff --git a/Documentation/devicetree/bindings/mfd/fm33256b.txt b/Documentation/devicetree/bindings/mfd/fm33256b.txt >>> new file mode 100644 >>> index 0000000..6591c94 >>> --- /dev/null >>> +++ b/Documentation/devicetree/bindings/mfd/fm33256b.txt >>> @@ -0,0 +1,30 @@ >>> +Device-tree bindings for Cypress Semiconductor FM33256B Processor Companion >>> +--------------------------------------------------------------------------- >>> + >>> +Required properties: >>> +- compatible: must be "cypress,fm33256b". >>> +- reg: SPI chip select >>> +- spi-max-frequency: Max SPI frequency to use (< 16000000) >>> + >>> +Optional properties: >>> +- cypress,charge-enabled: enable trickle charger >> >> What does the driver do if charging is disabled? Would using 'status = >> "disabled"' be any different? >> > > Good catch, I didn't look at this patch but it includes a lot of code > that should be going to the RTC driver. > If trickle charging is not enabled, I guess the RTC will not charge its > backup battery. Thank you for the comments. Alexandre is correct. If the "cypress,charge-enabled" property is present, the internal 80 uA trickle charger is enabled to charge a backup capacitor on the VBAK pin. Do you want more code than the trickle charger setup moved to the RTC driver? >>> +- cypress,charge-fast: enable fast (1 mA) charging >> >> What does fast mean? >> Fast charging means charging with 1 mA instead of 80 uA. The wording is from the datasheet, but I agree it should be renamed to something that better explains what the difference is. >> I think it is time for a common binding here. There's all sorts of >> variations on setting the charge current in bindings. Add something like >> "charge-current-microamp" in power_supply.txt and use it here. Then >> 1000uA implies "fast charge". > > Well, this is not a power supply, it is an RTC. > > I think both properties should got to the RTC subdevice and be parsed in > the RTC driver. The backup capacitor is primarily used to supply current to the RTC, but a couple of other registers are also battery-backed (watchdog reset cause, event counter), so I put the charger setup in the main MFD file. If you prefer, I can move them both to the RTC driver? > Note that for trickle charging, we currently have the following > properties: > - trickle-resistor-ohms > - trickle-diode-disable > - abracon,tc-diode > - abracon,tc-resistor > > abracon,tc-resistor can be replaced by trickle-resistor-ohms, I'll make > a patch but abracon,tc-diode allows to select a diode type (and in > particular a voltage drop). > > I think we could add a trickle-current-microamp like you suggested and > trickle-diode-disable can be reused. So replace "cypress,charge-enabled/charge-fast" with "trickle-current-microamp" and a check for 0/80/1000 uA? Thanks, -Jeppe -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
