linux-kernel - Re: [PATCH v4 2/4] Watchdog: sp5100_tco: Refactor MMIO base address initialization

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Date:   Tue, 1 Feb 2022 14:36:31 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Terry Bowman <Terry.Bowman@....com>,
        linux-watchdog@...r.kernel.org, jdelvare@...e.com,
        linux-i2c@...r.kernel.org, wsa@...nel.org,
        andy.shevchenko@...il.com, rafael.j.wysocki@...el.com
Cc:     linux-kernel@...r.kernel.org, wim@...ux-watchdog.org,
        rrichter@....com, thomas.lendacky@....com, sudheesh.mavila@....com,
        Nehal-bakulchandra.Shah@....com, Basavaraj.Natikar@....com,
        Shyam-sundar.S-k@....com, Mario.Limonciello@....com
Subject: Re: [PATCH v4 2/4] Watchdog: sp5100_tco: Refactor MMIO base address
 initialization

On 2/1/22 12:32, Terry Bowman wrote:
> 
> 
> On 2/1/22 10:46, Terry Bowman wrote:
>>
>>
>> On 2/1/22 09:31, Guenter Roeck wrote:
>>> On 1/30/22 11:12, Terry Bowman wrote:
>>>> Combine MMIO base address and alternate base address detection. Combine
>>>> based on layout type. This will simplify the function by eliminating
>>>> a switch case.
>>>>
>>>> Move existing request/release code into functions. This currently only
>>>> supports port I/O request/release. The move into a separate function
>>>> will make it ready for adding MMIO region support.
>>>>
>>>> Co-developed-by: Robert Richter <rrichter@....com>
>>>> Signed-off-by: Robert Richter <rrichter@....com>
>>>> Signed-off-by: Terry Bowman <terry.bowman@....com>
>>>> Tested-by: Jean Delvare <jdelvare@...e.de>
>>>> Reviewed-by: Jean Delvare <jdelvare@...e.de>
>>>> ---
>>>>    drivers/watchdog/sp5100_tco.c | 155 ++++++++++++++++++----------------
>>>>    drivers/watchdog/sp5100_tco.h |   1 +
>>>>    2 files changed, 82 insertions(+), 74 deletions(-)
>>>>
>>>> diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
>>>> index b365bbc9ac36..16e122d5045e 100644
>>>> --- a/drivers/watchdog/sp5100_tco.c
>>>> +++ b/drivers/watchdog/sp5100_tco.c
>>>> @@ -223,6 +223,55 @@ static u32 sp5100_tco_read_pm_reg32(u8 index)
>>>>        return val;
>>>>    }
>>>>    +static u32 sp5100_tco_request_region(struct device *dev,
>>>> +                     u32 mmio_addr,
>>>> +                     const char *dev_name)
>>>> +{
>>>> +    if (!devm_request_mem_region(dev, mmio_addr, SP5100_WDT_MEM_MAP_SIZE,
>>>> +                     dev_name)) {
>>>> +        dev_dbg(dev, "MMIO address 0x%08x already in use\n", mmio_addr);
>>>> +        return 0;
>>>> +    }
>>>> +
>>>> +    return mmio_addr;
>>>> +}
>>>> +
>>>> +static u32 sp5100_tco_prepare_base(struct sp5100_tco *tco,
>>>> +                   u32 mmio_addr,
>>>> +                   u32 alt_mmio_addr,
>>>> +                   const char *dev_name)
>>>> +{
>>>> +    struct device *dev = tco->wdd.parent;
>>>> +
>>>> +    dev_dbg(dev, "Got 0x%08x from SBResource_MMIO register\n", mmio_addr);
>>>> +
>>>> +    if (!mmio_addr && !alt_mmio_addr)
>>>> +        return -ENODEV;
>>>> +
>>>> +    /* Check for MMIO address and alternate MMIO address conflicts */
>>>> +    if (mmio_addr)
>>>> +        mmio_addr = sp5100_tco_request_region(dev, mmio_addr, dev_name);
>>>> +
>>>> +    if (!mmio_addr && alt_mmio_addr)
>>>> +        mmio_addr = sp5100_tco_request_region(dev, alt_mmio_addr, dev_name);
>>>> +
>>>> +    if (!mmio_addr) {
>>>> +        dev_err(dev, "Failed to reserve MMIO or alternate MMIO region\n");
>>>> +        return -EBUSY;
>>>> +    }
>>>> +
>>>> +    tco->tcobase = devm_ioremap(dev, mmio_addr, SP5100_WDT_MEM_MAP_SIZE);
>>>> +    if (!tco->tcobase) {
>>>> +        dev_err(dev, "MMIO address 0x%08x failed mapping\n", mmio_addr);
>>>> +        devm_release_mem_region(dev, mmio_addr, SP5100_WDT_MEM_MAP_SIZE);
>>>> +        return -ENOMEM;
>>>> +    }
>>>> +
>>>> +    dev_info(dev, "Using 0x%08x for watchdog MMIO address\n", tco->tcobase);
>>>> +
>>>
>>> I know this is the same as the old code, but I think it would make sense to change
>>> this as suggested by 0-day and use %px instead.
>>>
>>> Thanks,
>>> Guenter
>>
>>
> Hi Guenter,
> 
> This line was changed in v4 and should be reverted. It should be using the mmio_addr
> physical address with '0x%08x' formatting instead of tco->tcobase. This would be:
> 
> dev_info(dev, "Using 0x%08x for watchdog MMIO address\n", mmio_addr);
> 
> The dmesg then provides:
> 
> [    5.972921] sp5100_tco: SP5100/SB800 TCO WatchDog Timer Driver
> [    5.978238] sp5100-tco sp5100-tco: Using 0xfeb00000 for watchdog MMIO address
> [    5.978252] sp5100-tco sp5100-tco: Watchdog hardware is disabled
> 
> Do your agree?
> 

Yes. Displaying the mapped address has zero if any value.

Guenter