Messages in this thread | | | From | Tim Harvey <> | Date | Tue, 3 Apr 2018 08:48:27 -0700 | Subject | Re: [PATCH v3 2/4] mfd: add Gateworks System Controller core driver |
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On Wed, Mar 28, 2018 at 8:14 AM, Tim Harvey <tharvey@gateworks.com> wrote: > The Gateworks System Controller (GSC) is an I2C slave controller > implemented with an MSP430 micro-controller whose firmware embeds the > following features: > - I/O expander (16 GPIO's) using PCA955x protocol > - Real Time Clock using DS1672 protocol > - User EEPROM using AT24 protocol > - HWMON using custom protocol > - Interrupt controller with tamper detect, user pushbotton > - Watchdog controller capable of full board power-cycle > - Power Control capable of full board power-cycle > > see http://trac.gateworks.com/wiki/gsc for more details > <snip> > + > +/* > + * gsc_powerdown - API to use GSC to power down board for a specific time > + * > + * secs - number of seconds to remain powered off > + */ > +static int gsc_powerdown(struct gsc_dev *gsc, unsigned long secs) > +{ > + int ret; > + unsigned char regs[4]; > + > + dev_info(&gsc->i2c->dev, "GSC powerdown for %ld seconds\n", > + secs); > + regs[0] = secs & 0xff; > + regs[1] = (secs >> 8) & 0xff; > + regs[2] = (secs >> 16) & 0xff; > + regs[3] = (secs >> 24) & 0xff; > + ret = regmap_bulk_write(gsc->regmap, GSC_TIME_ADD, regs, 4); > + > + return ret; > +}
Any feedback on the 'powerdown' sysfs attribute that hooks to this function? This allows the GSC to disable the board primary power supply for 2^32 seconds and is often used to 'reset' the board although it could also be used to put the board in a power down state longer. I'm wondering if there is a more appropriate API for this in the kernel that I don't know about.
I would also like to register a restart handler using this but I believe that ARM restart handlers currently can not use I2C - is that correct?
Regards,
Tim
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