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linux/drivers/rtc
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Ahmad Fatoum c27fee16fa rtc: rv8803: re-initialize all Epson RX8803 registers on voltage loss 
The reference manuals of both the RX8803 and RV8803 dictate that
"[On V2F/VLF = ] all registers must be initialized".

The RV-8803 application manual (rev. 1.6) further specifies that crossing
V_LOW2 threshold enables flag V2F and triggers a Power-On reset.
According to table 3.11 in the document, all control registers are
defined to sensible values.

However, The Epson RX-8803 doesn't offer the same guarantees.
It explicitly states:

  During the initial power-up, the TEST bit is reset to "0" and the VLF
  bit is set to "1".
  ∗ At this point, all other register values are _undefined_, so be sure to
  perform a reset before using the module.

Commit d3700b6b64 ("rtc: rv8803: Stop the clock while setting the time")
also had this rationale:

  Indeed, all the registers must be initialized if the voltage has been
  lower than VLOW2 (triggering V2F), but not low enough to trigger a POR.

We should follow the advice and initialize all applicable registers.
We can group the registers into 3 groups:

A) Already correctly handled registers:
  * 0B-0Ch | Timer Counter  | unused and disabled by clearing TE in 0Dh
  * 0Dh    | Extension Reg  | already initialized in rv8803_regs_configure
  * 0Eh    | Flag Reg       | handled in IRQ handler, except for VLF, VDET
  * 0Eh    | VLF, VDET      | cleared in ->set_time
  * 10h    | 100th Seconds  | Already reset via RESET bit
  * 20-21h | Capture Buffer | holds timestamp unused by driver
  * 2Fh    | Event Control  | resets automatically

B) Registers that are hardware initialized on POR, but not on VLF:
  * 0Fh    | Control Reg
  * 2Ch    | OSC Offset

C) RAM that is undefined on voltage loss:
  * 00-06h | Date/Time
  * 07h    | RAM
  * 08-0Ah | Alarm

This means we should initialize after VLF the registers in group B
(RV8803_CTRL and RV8803_OSC_OFFSET).

Group C is all-zero after voltage loss on the RV-8803, but undefined on
the RX-8803. This is ok for Date/Time because ->get_time returns an
error code for as long as the voltage loss flag is active. It's cleared
on ->set_time however. Zeroing both RAM and alarm ensures a fixed value
is read afterwards.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/20220426071056.1187235-4-s.hauer@pengutronix.de
2022-06-24 21:24:02 +02:00
..
class.c rtc: remove uie_unsupported 2022-03-23 19:58:41 +01:00
dev.c rtc: Move variable into switch case statement 2022-01-05 01:03:09 +01:00
interface.c rtc: check if __rtc_read_time was successful 2022-03-29 22:45:50 +02:00
Kconfig rtc: rzn1: Add new RTC driver 2022-05-17 23:11:44 +02:00
lib.c rtc: Improve performance of rtc_time64_to_tm(). Add tests. 2021-08-10 00:09:21 +02:00
lib_test.c rtc: lib_test: add MODULE_LICENSE 2021-08-10 23:21:46 +02:00
Makefile rtc: rzn1: Add new RTC driver 2022-05-17 23:11:44 +02:00
nvmem.c rtc: nvmem: emit an error message when nvmem registration fails 2020-11-19 12:50:12 +01:00
proc.c rtc: fix snprintf() checking in is_rtc_hctosys() 2021-05-25 00:36:11 +02:00
rtc-88pm80x.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-88pm860x.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ab-b5ze-s3.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ab-eoz9.c rtc: ab-eoz9: support UIE when available 2021-11-10 00:45:57 +01:00
rtc-ab8500.c rtc: ab8500: let the core handle the alarm resolution 2021-11-10 00:45:57 +01:00
rtc-abx80x.c rtc: abx80x: Add utility function for writing configuration key 2021-02-13 23:03:26 +01:00
rtc-ac100.c rtc: ac100: use rtc_lock/rtc_unlock 2021-01-25 23:45:37 +01:00
rtc-armada38x.c rtc: armada38x: remove armada38x_rtc_ops_noirq 2021-01-16 23:19:26 +01:00
rtc-as3722.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 157 2019-05-30 11:26:37 -07:00
rtc-asm9260.c rtc: asm9260: use rtc_lock/rtc_unlock 2021-01-25 23:46:16 +01:00
rtc-aspeed.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-at91rm9200.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-at91sam9.c rtc: at91sam9: Remove unnecessary offset variable checks 2021-07-10 02:42:08 +02:00
rtc-au1xxx.c rtc: au1xxx: convert to SPDX identifier 2021-07-10 01:53:39 +02:00
rtc-bd70528.c rtc: bd70528: Drop BD70528 support 2021-06-20 22:24:52 +02:00
rtc-bq32k.c rtc: bq32k: quiet maybe-unused variable warning 2021-02-06 00:58:24 +01:00
rtc-bq4802.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
rtc-brcmstb-waketimer.c rtc: brcmstb-waketimer: quiet maybe-unused variable warning 2021-02-06 00:58:24 +01:00
rtc-cadence.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-cmos.c rtc: cmos: avoid UIP when writing alarm time 2021-12-16 21:50:07 +01:00
rtc-core.h
rtc-cpcap.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-cros-ec.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-da9052.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-da9055.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
rtc-da9063.c rtc: da9063: add as wakeup source 2021-12-02 23:23:38 +01:00
rtc-davinci.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-digicolor.c rtc: digicolor: quiet maybe-unused variable warning 2021-02-06 00:58:24 +01:00
rtc-dm355evm.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ds1216.c rtc: use devm_platform_ioremap_resource() to simplify code 2019-10-07 01:07:35 +02:00
rtc-ds1286.c rtc: use devm_platform_ioremap_resource() to simplify code 2019-10-07 01:07:35 +02:00
rtc-ds1302.c spi: make remove callback a void function 2022-02-09 13:00:45 +00:00
rtc-ds1305.c spi: make remove callback a void function 2022-02-09 13:00:45 +00:00
rtc-ds1307.c rtc: ds1307: switch to RTC_FEATURE_UPDATE_INTERRUPT 2022-03-23 19:58:38 +01:00
rtc-ds1343.c spi: make remove callback a void function 2022-02-09 13:00:45 +00:00
rtc-ds1347.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ds1374.c rtc: ds1374: convert to SPDX identifier 2021-07-10 01:53:39 +02:00
rtc-ds1390.c rtc: ds1390: Add SPI ID table 2021-09-25 23:22:28 +02:00
rtc-ds1511.c rtc: ds1511: remove unused function 2021-04-17 11:21:04 +02:00
rtc-ds1553.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ds1672.c rtc: ds1672: quiet maybe-unused variable warning 2021-02-06 00:58:24 +01:00
rtc-ds1685.c rtc: ds1685: drop no_irq 2022-03-23 19:58:38 +01:00
rtc-ds1742.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ds2404.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ds3232.c rtc: ds3232: quiet maybe-unused variable warning 2021-02-06 00:58:24 +01:00
rtc-efi.c rtc: efi: switch to RTC_FEATURE_UPDATE_INTERRUPT 2022-03-23 19:58:40 +01:00
rtc-em3027.c rtc: em3027: correct month value 2019-11-08 16:14:09 +01:00
rtc-ep93xx.c rtc: ep93xx: Fix NULL pointer dereference in ep93xx_rtc_read_time 2020-12-03 23:49:31 +01:00
rtc-fm3130.c RTC for 5.3 2019-07-17 10:03:50 -07:00
rtc-fsl-ftm-alarm.c rtc: fsl-ftm-alarm: add MODULE_TABLE() 2021-04-17 11:21:04 +02:00
rtc-ftrtc010.c rtc: ftrtc010: Fix error handling in ftrtc010_rtc_probe 2022-05-19 12:08:17 +02:00
rtc-gamecube.c rtc: gamecube: Add missing iounmap in gamecube_rtc_read_offset_from_sram 2022-05-18 14:52:17 +02:00
rtc-generic.c treewide: Add SPDX license identifier for more missed files 2019-05-21 10:50:45 +02:00
rtc-goldfish.c clocksource/drivers: Add a goldfish-timer clocksource 2022-04-11 11:48:01 +02:00
rtc-hid-sensor-time.c iio: hid-sensors: lighten exported symbols by moving to IIO_HID namespace 2021-06-16 14:53:13 +01:00
rtc-hym8563.c rtc: hym8563: switch to RTC_FEATURE_UPDATE_INTERRUPT 2022-03-23 19:58:40 +01:00
rtc-imx-sc.c rtc: imx-sc: remove .read_alarm 2021-04-29 23:03:26 +02:00
rtc-imxdi.c rtc: imxdi: add wakeup support 2021-05-25 00:41:25 +02:00
rtc-isl1208.c rtc: isl1208: quiet maybe-unused variable warning 2021-02-06 00:58:24 +01:00
rtc-isl12022.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-isl12026.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-jz4740.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-lp8788.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-lpc24xx.c rtc: remove unnecessary error message after platform_get_irq 2020-04-15 09:56:17 +02:00
rtc-lpc32xx.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-ls1x.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-m41t80.c rtc: m41t80: switch to RTC_FEATURE_UPDATE_INTERRUPT 2022-03-23 19:58:39 +01:00
rtc-m41t93.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-m41t94.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-m48t35.c rtc: m48t35: remove SGI-IP27 kludge 2020-03-16 11:12:11 +01:00
rtc-m48t59.c rtc: m48t59: use platform_get_irq_optional 2021-03-11 09:48:09 +01:00
rtc-m48t86.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-max6900.c rtc: max6900: convert to SPDX identifier 2021-07-10 01:53:39 +02:00
rtc-max6902.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-max6916.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-max8907.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-max8925.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-max8997.c
rtc-max8998.c
rtc-max77686.c rtc: max77686: Add MAX77714 support 2022-03-07 13:55:04 +00:00
rtc-mc13xxx.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-mc146818-lib.c rtc: mc146818-lib: reduce RTC_UIP polling period 2022-06-24 21:23:50 +02:00
rtc-mcp795.c rtc: mcp795: Add SPI ID table 2021-10-01 23:28:28 +02:00
rtc-meson-vrtc.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-meson.c rtc: meson: Fix email address in MODULE_AUTHOR 2022-05-18 00:20:39 +02:00
rtc-moxart.c rtc: moxart: Convert to SPDX identifier 2019-12-23 11:23:49 +01:00
rtc-mpc5121.c rtc: mpc5121: switch to RTC_FEATURE_UPDATE_INTERRUPT 2022-03-23 19:58:38 +01:00
rtc-msc313.c rtc: msc313: Fix unintentional sign extension issues with left shift of a u16 2021-10-01 23:28:46 +02:00
rtc-msm6242.c rtc: msm6242: Remove unneeded msm6242_set()/msm6242_clear() functions 2019-11-18 15:23:54 +01:00
rtc-mt2712.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-mt6397.c rtc: mt6397: check return value after calling platform_get_resource() 2022-05-19 12:05:48 +02:00
rtc-mt7622.c rtc: use devm_platform_ioremap_resource() to simplify code 2019-10-07 01:07:35 +02:00
rtc-mv.c rtc: mv: remove mv_rtc_alarm_ops 2021-01-16 23:19:26 +01:00
rtc-mxc.c rtc: mxc: Silence a clang warning 2022-06-01 23:19:17 +02:00
rtc-mxc_v2.c rtc: mxc_v2: add missing MODULE_DEVICE_TABLE 2021-05-25 00:33:17 +02:00
rtc-ntxec.c rtc: New driver for RTC in Netronix embedded controller 2021-03-10 11:06:33 +00:00
rtc-omap.c rtc: omap: drop unneeded MODULE_ALIAS 2021-09-25 23:26:37 +02:00
rtc-opal.c rtc: opal: switch to RTC_FEATURE_UPDATE_INTERRUPT 2022-03-23 19:58:39 +01:00
rtc-optee.c rtc: optee: add RTC driver for OP-TEE RTC PTA 2022-03-25 11:42:50 +01:00
rtc-palmas.c rtc: palmas: convert to SPDX identifier 2021-07-10 01:53:39 +02:00
rtc-pcap.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-pcf2123.c rtc: pcf2123: set RTC_FEATURE_ALARM_RES_MINUTE 2022-03-23 19:58:39 +01:00
rtc-pcf2127.c rtc: pcf2127: set RTC_FEATURE_ALARM_RES_2S 2022-03-23 19:58:39 +01:00
rtc-pcf8523.c rtc: pcf8523: let the core handle the alarm resolution 2022-03-23 19:58:39 +01:00
rtc-pcf8563.c rtc: pcf8563: switch to RTC_FEATURE_UPDATE_INTERRUPT 2022-03-23 19:58:40 +01:00
rtc-pcf8583.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-pcf50633.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
rtc-pcf85063.c rtc: pcf85063: Add a compatible entry for pca85073a 2022-05-18 00:15:50 +02:00
rtc-pcf85363.c rtc: pcf85363: quiet maybe-unused variable warning 2021-02-06 00:58:25 +01:00
rtc-pic32.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-pl030.c amba: Make the remove callback return void 2021-02-02 14:25:50 +01:00
rtc-pl031.c rtc: pl031: fix rtc features null pointer dereference 2022-03-23 19:58:37 +01:00
rtc-pm8xxx.c rtc: pm8xxx: Return -ENODEV if set_time disallowed 2022-03-25 11:38:33 +01:00
rtc-ps3.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-pxa.c ARM: pxa: split up mach/hardware.h 2022-04-19 16:27:05 +02:00
rtc-r7301.c rtc: r7301: Replace spin_lock_irqsave with spin_lock in hard IRQ 2021-02-06 00:50:47 +01:00
rtc-r9701.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rc5t583.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 201 2019-05-30 11:29:52 -07:00
rtc-rc5t619.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rk808.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rp5c01.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rs5c313.c rtc: rtc-rs5c313: Convert to module_platform_driver() 2020-08-21 00:13:44 +02:00
rtc-rs5c348.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-rs5c372.c rtc: rs5c372: fix incorrect oscillation value on r2221tl 2022-01-05 00:52:10 +01:00
rtc-rtd119x.c rtc: rtd119x: Fix format of SPDX identifier 2021-07-10 01:53:39 +02:00
rtc-rv3028.c rtc: rv3028: add BSM support 2021-10-18 17:20:50 +02:00
rtc-rv3029c2.c rtc: rv3029: quiet maybe-unused variable warning 2021-02-06 00:58:25 +01:00
rtc-rv3032.c rtc: rv3032: let the core handle the alarm resolution 2021-11-10 00:45:57 +01:00
rtc-rv8803.c rtc: rv8803: re-initialize all Epson RX8803 registers on voltage loss 2022-06-24 21:24:02 +02:00
rtc-rx4581.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-rx6110.c rtc: rx6110: simplify getting the adapter of a client 2021-09-25 23:27:39 +02:00
rtc-rx8010.c rtc: rx8010: quiet maybe-unused variable warning 2021-02-06 00:58:25 +01:00
rtc-rx8025.c rtc: simplify the return expression of rx8025_set_offset() 2022-05-18 00:18:19 +02:00
rtc-rx8581.c rtc: rx8581: quiet maybe-unused variable warning 2021-02-06 00:58:25 +01:00
rtc-rzn1.c rtc: rzn1: Fix a variable type 2022-05-25 01:24:21 +02:00
rtc-s3c.c rtc: s3c: Add time range 2021-10-23 23:57:23 +02:00
rtc-s3c.h treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-s5m.c rtc: s5m: drop unneeded MODULE_ALIAS 2021-09-25 23:26:37 +02:00
rtc-s35390a.c rtc: s35390a: let the core handle the alarm resolution 2021-11-10 00:45:57 +01:00
rtc-sa1100.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-sa1100.h
rtc-sc27xx.c rtc: sc27xx: Fix format of SPDX identifier 2021-07-10 01:53:39 +02:00
rtc-sd3078.c rtc: sd3078: quiet maybe-unused variable warning 2021-02-06 00:58:26 +01:00
rtc-sh.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-snvs.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-spear.c rtc: spear: fix spear_rtc_read_time 2022-03-23 19:58:40 +01:00
rtc-st-lpc.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-starfire.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-stk17ta8.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-stm32.c rtc: stm32: Fix unbalanced clk_disable_unprepare() on probe error path 2021-06-20 22:28:02 +02:00
rtc-stmp3xxx.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-sun4v.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-sun6i.c RTC for 5.19 2022-06-01 14:48:13 -07:00
rtc-sunplus.c rtc: sunplus: fix return value in sp_rtc_probe() 2022-01-16 23:50:34 +01:00
rtc-sunxi.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-tegra.c rtc: tegra: Replace spin_lock_irqsave with spin_lock in hard IRQ 2021-02-06 00:50:47 +01:00
rtc-test.c rtc: test: remove debug message 2020-12-03 23:43:23 +01:00
rtc-tps6586x.c rtc: tps6586x: convert to SPDX identifier 2021-07-10 01:53:40 +02:00
rtc-tps65910.c rtc: tps65910: Correct driver module alias 2021-08-17 23:36:22 +02:00
rtc-twl.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152 2019-05-30 11:26:32 -07:00
rtc-v3020.c rtc: v3020: remove redundant initialization of variable retval 2021-06-20 22:29:50 +02:00
rtc-vr41xx.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-vt8500.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-wilco-ec.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-wm831x.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
rtc-wm8350.c rtc: wm8350: Handle error for wm8350_register_irq 2022-03-23 19:58:38 +01:00
rtc-x1205.c treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
rtc-xgene.c rtc: xgene: stop using uie_unsupported 2022-03-23 19:58:41 +01:00
rtc-zynqmp.c rtc: rework rtc_register_device() resource management 2020-11-19 12:50:12 +01:00
sysfs.c rtc: sysfs: Correct kerneldoc function name hctosys_show() 2021-06-20 22:18:05 +02:00