kernel/linux.git/drivers/rtc/rtc-isl12022.c, branch v6.6.148

rtc: isl12022: implement support for the #clock-cells DT property

2023-08-15T23:27:01+00:00

If device tree implies that the chip's IRQ/F_OUT pin is used as a clock, expose that in the driver. For now, pretend it is a fixed-rate (32kHz) clock; if other use cases appear the driver can be updated to provide its own clk_ops etc. When the clock output is not used on a given board, one can prolong the battery life by ensuring that the FOx bits are 0. For the hardware I'm currently working on, the RTC draws 1.2uA with the FOx bits at their default 0001 value, dropping to 0.88uA when those bits are cleared. Signed-off-by: Rasmus Villemoes Link: https://lore.kernel.org/r/20230615105826.411953-9-linux@rasmusvillemoes.dk Signed-off-by: Alexandre Belloni

rtc: isl12022: trigger battery level detection during probe

2023-08-15T23:27:01+00:00

Since the meaning of the SR_LBAT85 and SR_LBAT75 bits are different in battery backup mode, they may very well be set after power on, and stay set for up to a minute (i.e. until the battery detection in VDD mode happens when the seconds counter hits 59). This would mean that userspace doing a ioctl(RTC_VL_READ) early on could get a false positive. The battery level detection can also be triggered by explicitly writing a 1 to the TSE bit in the BETA register. Do that once during boot. Empirically, this does not immediately update the bits in the status register (i.e., an immediate read of SR after this write can still show stale values), but the update is done after a few milliseconds, so certainly before the RTC device gets registered and userspace has a chance of doing the ioctl() on this device. Signed-off-by: Rasmus Villemoes Link: https://lore.kernel.org/r/20230615105826.411953-7-linux@rasmusvillemoes.dk Signed-off-by: Alexandre Belloni

rtc: isl12022: implement RTC_VL_READ ioctl

2023-08-15T23:27:01+00:00

Hook up support for reading the values of the SR_LBAT85 and SR_LBAT75 bits. Translate the former to "battery low", and the latter to "battery empty or not-present". Signed-off-by: Rasmus Villemoes Link: https://lore.kernel.org/r/20230615105826.411953-6-linux@rasmusvillemoes.dk Signed-off-by: Alexandre Belloni

rtc: isl12022: add support for trip level DT binding

2023-08-15T23:27:01+00:00

Implement support for using the values given in the isil,battery-trip-levels-microvolt property to set appropriate values in the VB85TP/VB75TP bits in the PWR_VBAT register. Signed-off-by: Rasmus Villemoes Link: https://lore.kernel.org/r/20230615105826.411953-5-linux@rasmusvillemoes.dk Signed-off-by: Alexandre Belloni

rtc: isl12022: remove wrong warning for low battery level

2023-08-15T23:27:01+00:00

There are multiple problems with this warning. First of all, it triggers way too often, in fact nearly on every boot, because the SR_LBAT85/SR_LBAT75 bits have another meaning when in battery backup mode. Quoting from the data sheet: LOW BATTERY INDICATOR 85% BIT (LBAT85) In Normal Mode (VDD), this bit indicates when the battery level has dropped below the pre-selected trip levels. [...] The LBAT85 detection happens automatically once every minute when seconds register reaches 59. In Battery Mode (VBAT), this bit indicates the device has entered into battery mode by polling once every 10 minutes. The LBAT85 detection happens automatically once when the minute register reaches x9h or x0h minutes. Similar wording applies to the LBAT75 bit. This means that if the device is powered off for more than 10 minutes, the LBAT85 bit is guaranteed to be set. Upon power-on, unless we're close enough to the end of a minute and/or the boot is slow enough that the second register passes 59, the LBAT85 bit is still set when the kernel (or early userspace) reads the RTC to set the system's wallclock time. Another minor problem is with the bit logic. If the 75% level is reached, logically we're also below 85%, so both bits would most likely be set. So even if the battery is below 75%, the warning would still say "voltage dropped below 85%". A third problem is that the driver and current DT binding offer no way to indicate the nominal battery level and/or settings of the Battery Level Monitor Trip Bits. Since the default value of the VB85TP[2:0] and VB75TP[2:0] bits are 000, this means the actual setting of the LBAT85/LBAT75 bits in VDD mode doesn't happen until the battery is below 2.125V/1.875V, which for a standard 3V battery is way too late. A fourth problem is emitting this warning from ->read_time: util-linux' hwclock will, in the absence of support for getting an interrupt when the seconds counter is updated, issue ioctl(RTC_RD_TIME) in a busy-loop until it sees a change in the seconds field. In that case, if the battery low bits are set (either genuinely, more than a minute after boot, due to the battery actually being low, or as above, bogusly shortly after boot), the kernel log is swamped with hundreds of identical warnings. Subsequent patches will add such bindings and driver support, and also proper support for RTC_VL_READ. For now, remove the broken warning. Signed-off-by: Rasmus Villemoes Link: https://lore.kernel.org/r/20230615105826.411953-2-linux@rasmusvillemoes.dk Signed-off-by: Alexandre Belloni

rtc: Switch i2c drivers back to use .probe()

2023-06-06T21:29:37+00:00

After commit b8a1a4cd5a98 ("i2c: Provide a temporary .probe_new() call-back type"), all drivers being converted to .probe_new() and then 03c835f498b5 ("i2c: Switch .probe() to not take an id parameter") convert back to (the new) .probe() to be able to eventually drop .probe_new() from struct i2c_driver. Signed-off-by: Uwe Kleine-König Link: https://lore.kernel.org/r/20230505121136.1185653-1-u.kleine-koenig@pengutronix.de Signed-off-by: Alexandre Belloni

rtc: isl12022: constify pointers to hwmon_channel_info

2023-06-06T21:24:54+00:00

Statically allocated array of pointers to hwmon_channel_info can be made const for safety. Signed-off-by: Krzysztof Kozlowski Link: https://lore.kernel.org/r/20230511175609.282191-3-krzysztof.kozlowski@linaro.org Signed-off-by: Alexandre Belloni

rtc: isl12022: sort header inclusion alphabetically

2023-02-22T20:06:30+00:00

Sort header inclusion alphabetically for better maintenance. Signed-off-by: Andy Shevchenko Acked-by: Rasmus Villemoes Link: https://lore.kernel.org/r/20230110140806.87432-6-andriy.shevchenko@linux.intel.com Signed-off-by: Alexandre Belloni

rtc: isl12022: Join string literals back

2023-02-22T20:06:30+00:00

For easy grepping on debug purposes join string literals back in the messages. While at it, drop __func__ parameter from unique enough dev_dbg() message as Dynamic Debug can retrieve this at run time. Signed-off-by: Andy Shevchenko Acked-by: Rasmus Villemoes Link: https://lore.kernel.org/r/20230110140806.87432-5-andriy.shevchenko@linux.intel.com Signed-off-by: Alexandre Belloni

rtc: isl12022: Drop unneeded OF guards and of_match_ptr()

2023-02-22T20:06:30+00:00

Drop unneeded OF guards and of_match_ptr(). This allows use of the driver with other types of firmware such as ACPI PRP0001 based probing. Signed-off-by: Andy Shevchenko Link: https://lore.kernel.org/r/20230110140806.87432-4-andriy.shevchenko@linux.intel.com Signed-off-by: Alexandre Belloni