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Date: Tue, 25 Jan 2022 14:45:20 +0100
From: Jean Delvare <jdelvare@...e.de>
To: Terry Bowman <terry.bowman@....com>
Cc: <linux@...ck-us.net>, <linux-watchdog@...r.kernel.org>,
<linux-i2c@...r.kernel.org>, <wsa@...nel.org>,
<andy.shevchenko@...il.com>, <rafael.j.wysocki@...el.com>,
<linux-kernel@...r.kernel.org>, <wim@...ux-watchdog.org>,
<rrichter@....com>, <thomas.lendacky@....com>,
<Nehal-bakulchandra.Shah@....com>, <Basavaraj.Natikar@....com>,
<Shyam-sundar.S-k@....com>, <Mario.Limonciello@....com>
Subject: Re: [PATCH v3 2/4] Watchdog: sp5100_tco: Refactor MMIO base address
initialization
Hi Terry,
Sorry for the late review, I hope you did not send an updated series
already.
On Tue, 18 Jan 2022 14:22:32 -0600, 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.
>
> (...)
> +static int __sp5100_tco_prepare_base(struct sp5100_tco *tco,
> + u32 mmio_addr,
> + const char *dev_name)
> +{
> + struct device *dev = tco->wdd.parent;
> + int ret = 0;
> +
> + if (!mmio_addr)
> + return -ENOMEM;
Can this actually happen? If it does, is -ENOMEM really the best error
value?
And if it can happen, I think I would prefer if you would simply not
call this function, knowing it can only fail. In other words, I'd go
for something like the following in the function below:
/* Check MMIO address conflict */
if (mmio_addr)
ret = __sp5100_tco_prepare_base(tco, mmio_addr, dev_name);
The intention is clearer and execution is faster too.
> +
> + 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 -EBUSY;
> + }
> +
> + tco->tcobase = devm_ioremap(dev, mmio_addr,
> + SP5100_WDT_MEM_MAP_SIZE);
> + if (!tco->tcobase) {
> + dev_dbg(dev, "MMIO address 0x%08x failed mapping.\n",
> + mmio_addr);
Remove trailing dot for consistency with the other messages.
> + 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",
> + mmio_addr);
> +
> + return ret;
> +}
> +
> +static int 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;
> + int ret = 0;
> +
> + dev_dbg(dev, "Got 0x%08x from SBResource_MMIO register\n",
> + mmio_addr);
> +
> + /* Check MMIO address conflict */
> + ret = __sp5100_tco_prepare_base(tco, mmio_addr, dev_name);
> +
> + /* Check alternate MMIO address conflict */
> + if (ret)
> + ret = __sp5100_tco_prepare_base(tco, alt_mmio_addr,
> + dev_name);
> +
> + if (ret)
> + dev_err(dev, "Failed to reserve-map MMIO (%X) and alternate MMIO (%X) regions. ret=%X",
> + mmio_addr, alt_mmio_addr, ret);
Format for the addresses is inconsistent with the other messages above,
please use 0x%08x for consistency. As for the return value (which
should be preceded by a comma rather than a dot), it should be printed
as a decimal, not hexadecimal, value.
(And nitpicking: I'd split after "dev," so as to not make the line
longer than needed.
> +
> + return ret;
> +}
> +
> static int sp5100_tco_timer_init(struct sp5100_tco *tco)
> {
> struct watchdog_device *wdd = &tco->wdd;
> @@ -264,6 +324,7 @@ static int sp5100_tco_setupdevice(struct device *dev,
> struct sp5100_tco *tco = watchdog_get_drvdata(wdd);
> const char *dev_name;
> u32 mmio_addr = 0, val;
> + u32 alt_mmio_addr = 0;
> int ret;
>
> /* Request the IO ports used by this driver */
> @@ -282,11 +343,35 @@ static int sp5100_tco_setupdevice(struct device *dev,
> dev_name = SP5100_DEVNAME;
> mmio_addr = sp5100_tco_read_pm_reg32(SP5100_PM_WATCHDOG_BASE) &
> 0xfffffff8;
> +
> + /*
> + * Secondly, Find the watchdog timer MMIO address
> + * from SBResource_MMIO register.
> + */
> + /* Read SBResource_MMIO from PCI config(PCI_Reg: 9Ch) */
> + pci_read_config_dword(sp5100_tco_pci,
> + SP5100_SB_RESOURCE_MMIO_BASE,
> + &alt_mmio_addr);
> + if (alt_mmio_addr & ((SB800_ACPI_MMIO_DECODE_EN |
> + SB800_ACPI_MMIO_SEL) !=
> + SB800_ACPI_MMIO_DECODE_EN)) {
> + alt_mmio_addr &= ~0xFFF;
> + alt_mmio_addr += SB800_PM_WDT_MMIO_OFFSET;
> + }
> break;
> case sb800:
> dev_name = SB800_DEVNAME;
> mmio_addr = sp5100_tco_read_pm_reg32(SB800_PM_WATCHDOG_BASE) &
> 0xfffffff8;
> + /* Read SBResource_MMIO from AcpiMmioEn(PM_Reg: 24h) */
> + alt_mmio_addr =
> + sp5100_tco_read_pm_reg32(SB800_PM_ACPI_MMIO_EN);
> + if (!(alt_mmio_addr & (((SB800_ACPI_MMIO_DECODE_EN |
> + SB800_ACPI_MMIO_SEL)) !=
> + SB800_ACPI_MMIO_DECODE_EN))) {
The condition is the opposite of the sp5100 case above, which looks
quite suspicious. As far as I can see, that wasn't the case in the
original code. Please double check. In any case, please avoid double
negations, they are too easy to get wrong.
> + alt_mmio_addr &= ~0xFFF;
> + alt_mmio_addr += SB800_PM_WDT_MMIO_OFFSET;
> + }
> break;
> case efch:
> dev_name = SB800_DEVNAME;
> @@ -305,87 +390,24 @@ static int sp5100_tco_setupdevice(struct device *dev,
> val = sp5100_tco_read_pm_reg8(EFCH_PM_DECODEEN);
> if (val & EFCH_PM_DECODEEN_WDT_TMREN)
> mmio_addr = EFCH_PM_WDT_ADDR;
> +
> + val = sp5100_tco_read_pm_reg8(EFCH_PM_ISACONTROL);
> + if (val & EFCH_PM_ISACONTROL_MMIOEN)
> + alt_mmio_addr = EFCH_PM_ACPI_MMIO_ADDR +
> + EFCH_PM_ACPI_MMIO_WDT_OFFSET;
> break;
> default:
> return -ENODEV;
> }
> (...)
Rest looks OK to me.
--
Jean Delvare
SUSE L3 Support
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