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

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Message-ID: <e7112674-05e2-93cd-b8f9-3e31f173238d@amd.com>
Date:   Tue, 1 Feb 2022 14:32:45 -0600
From:   Terry Bowman <Terry.Bowman@....com>
To:     Guenter Roeck <linux@...ck-us.net>, 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 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?

Regards,
Terry