lkml.org 
[lkml]   [2023]   [Jun]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 00/14] rtc: pcf2127: add PCF2131 driver
    On Wed, 21 Jun 2023 10:14:29 -0400
    Hugo Villeneuve <hugo@hugovil.com> wrote:

    > On Fri, 20 Jan 2023 20:05:07 +0100
    > Alexandre Belloni <alexandre.belloni@bootlin.com> wrote:
    >
    > > Hello,
    > >
    > > I know I've been holding off on the review of this series for a while
    > > and I'm sorry for that.
    > >
    > > One of the main issue that is remaining is that the driver ends up being
    > > 53% bigger and generaly less efficient for no added functionality for
    > > the existing RTCs.
    > >
    > > I know performance is not a concern however, having more code in the
    > > set/read time and irq paths means that it is more difficult to set an
    > > get the time precisely.
    >
    > Hi Alexandre,
    > one way to keep rtc_read_time() as efficient as before, and even more
    > efficient by reading 7 instead of 10 registers, would be to drop reading
    > the CTRL3 register, which is only used to detect and display an info
    > message for the low battery condition. This low battery check could be
    > moved to an ioctl call, like it is done in the PCF8523 driver.
    >
    > Hugo.

    Hi,
    in fact it is already part of the ioctl, so it is even simpler...

    Hugo.


    >
    >
    > > I guess I'll take it as a merged driver but I took a different decision
    > > for other RTCs.
    > >
    > > On 15/12/2022 10:02:01-0500, Hugo Villeneuve wrote:
    > > > From: Hugo Villeneuve <hvilleneuve@dimonoff.com>
    > > >
    > > > Hello,
    > > > this patch series adds the driver for the PCF2131 real-time clock.
    > > >
    > > > This RTC is very similar in functionality to the PCF2127/29 with the
    > > > following differences:
    > > > -supports two new control registers at offsets 4 and 5
    > > > -supports a new reset register
    > > > -supports 4 tamper detection functions instead of 1
    > > > -has no nvmem (like the PCF2129)
    > > > -has two output interrupt pins instead of one
    > > > -has 1/100th seconds capabilities (not supported in this driver)
    > > > -pcf2127 has watchdog clock sources: 1/60, 1, 64 and 4096Hz
    > > > pcf2131 has watchdog clock sources: 1/64, 1/4, 4 and 64Hz
    > > > -watchdog value register cannot be read after being set
    > > >
    > > > Most of the register addresses are very different, although they still
    > > > follow the same layout. For example, the time/date and tamper registers
    > > > have a different base address, but the offsets are all the same.
    > > > Consequently, the source code of the PCF2127 driver can be easily adapted
    > > > to support this new device.
    > > >
    > > > Patches 1 to 6 modify the existing pcf2127 driver to make it more generic
    > > > and able to support multiple variants, like the PCF2131. This is done
    > > > mostly by using offsets instead of absolute hardcoded register addresses.
    > > >
    > > > Patch 7 add actual support for the PCF2131.
    > > >
    > > > Patch 8 configures all interrupt sources to go through the INT A pin.
    > > >
    > > > Patch 9 changes the PWRMNG bits to be the same with the PCF2131 as they
    > > > are with the PCF2127/29 (different default values).
    > > >
    > > > Patch 10 allow to confirm PCF2131 device presence by reading the reset
    > > > register fixed pattern.
    > > >
    > > > Patch 11 adapt the time/date registers write sequence for PCF2131 (STOP and
    > > > CPR bits).
    > > >
    > > > Patch 12 add support for generic watchdog timing configuration.
    > > >
    > > > Patch 13 add a new flag to identify if device has read support for reading
    > > > watchdog register value.
    > > > Since the watchdog value register cannot be read on the PCF2131 after
    > > > being set, it seems that we cannot detect if watchdog timer was
    > > > started by bootloader. I am not sure what is the best way to handle
    > > > this situation, suggestions are welcomed.
    > > >
    > > > Patch 14 add the dt-bindings for the PCF2131.
    > > >
    > > > I have tested the driver using a PCF2131-ARD evaluation board connected to
    > > > an NXP imx8mp evaluation board:
    > > > - Time get/set ok;
    > > > - Alarms get/set ok
    > > > - Timestamp 1 to 4 ok
    > > > - IRQ alarm ok
    > > > - Watchdog ok
    > > > - Also tested successfully with "RTC Driver Test Example" from
    > > > Documentation/rtc.txt
    > > >
    > > > I have also tested the driver on a custom PCF2129 adapter board connected to a
    > > > beaglebone black.
    > > >
    > > > Thank you.
    > > >
    > > > Link: [v1] https://patchwork.ozlabs.org/project/rtc-linux/patch/20220125200009.900660-2-hugo@hugovil.com/
    > > > Link: [v2] https://patchwork.ozlabs.org/project/rtc-linux/list/?series=285734
    > > >
    > > > Changes for V3:
    > > > - Rebased for kernel v6.1
    > > >
    > > > Changes for V2:
    > > > - In general, fix and improvements after I have tested on real hardware
    > > > - Fix alarm interrupt A/B mask setting for PCF2131:
    > > > PCF2131_BIT_INT_AIE must be cleared, not set, to enable interrupt.
    > > > - Remove low_reg validation: only check if TS interrupt flag is
    > > > defined, as low_reg is defined at address 0 for PCF2127/29.
    > > > - Change PWRMNG value for PCF2131: default is different than PCF2127/29.
    > > > - Adapt time/date registers write sequence for PCF2131 (STOP and CPR bits).
    > > > - Map all interrupt sources to INT A pin
    > > > - Read and validate PCF2131 device presence from RESET register
    > > > - Adapt watchdog configuration for PCF2131
    > > >
    > > > Hugo Villeneuve (14):
    > > > rtc: pcf2127: add variant-specific configuration structure
    > > > rtc: pcf2127: adapt for time/date registers at any offset
    > > > rtc: pcf2127: adapt for alarm registers at any offset
    > > > rtc: pcf2127: adapt for WD registers at any offset
    > > > rtc: pcf2127: adapt for CLKOUT register at any offset
    > > > rtc: pcf2127: add support for multiple TS functions
    > > > rtc: pcf2127: add support for PCF2131 RTC
    > > > rtc: pcf2127: add support for PCF2131 interrupts on output INT_A
    > > > rtc: pcf2127: set PWRMNG value for PCF2131
    > > > rtc: pcf2127: read and validate PCF2131 device signature
    > > > rtc: pcf2127: adapt time/date registers write sequence for PCF2131
    > > > rtc: pcf2127: support generic watchdog timing configuration
    > > > rtc: pcf2127: add flag for watchdog register value read support
    > > > dt-bindings: rtc: pcf2127: add PCF2131
    > > >
    > > > .../devicetree/bindings/rtc/nxp,pcf2127.yaml | 4 +-
    > > > drivers/rtc/Kconfig | 4 +-
    > > > drivers/rtc/rtc-pcf2127.c | 939 ++++++++++++++----
    > > > 3 files changed, 752 insertions(+), 195 deletions(-)
    > > >
    > > > --
    > > > 2.30.2
    > > >
    > >
    > > --
    > > Alexandre Belloni, co-owner and COO, Bootlin
    > > Embedded Linux and Kernel engineering
    > > https://bootlin.com
    > >

    \
     
     \ /
      Last update: 2023-06-21 19:01    [W:8.005 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site