Re: [PATCH v7 3/6] watchdog: iTCO_wdt: cleanup set/unset no_reboot_bit functions

[Guenter Roeck]

On 04/09/2017 03:00 PM, Kuppuswamy Sathyanarayanan wrote:
> iTCO_wdt no_reboot_bit set/unset functions has lot of common code between
> them. So merging these two functions into a single update function would
> remove these unnecessary code duplications. This patch fixes this issue
> by creating a no_reboot_bit update function to handle both set/unset
> functions.
>
> Also checking for iTCO version every time you make no_reboot_bit set/unset
> call is inefficient and makes the code look complex. This can be improved
> by performing this check once during device probe and selecting the
> appropriate no_reboot_bit update function. This patch fixes this issue
> by splitting the update function into multiple helper functions.
>
> Signed-off-by: Kuppuswamy Sathyanarayanan <sathyanarayanan.kuppuswamy@xxxxxxxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

> ---
>  drivers/watchdog/iTCO_wdt.c | 83 +++++++++++++++++++++++++++------------------
>  1 file changed, 50 insertions(+), 33 deletions(-)
>
> Changes since v6:
>  * make iTCO_wdt_no_reboot_bit_setup() static
>  * remove inline specifier for update_no_reboot_bit helper functions.
>
> Changes since v5:
>  * Changed update function argument name from "status" to "set".
>  * Fixed commit history.
>  * Changed update function name to use "bit" instead of "flag"
>  * Addressed Andy's comment on creating multiple helper functions.
>
> diff --git a/drivers/watchdog/iTCO_wdt.c b/drivers/watchdog/iTCO_wdt.c
> index 3d0abc0..a629933 100644
> --- a/drivers/watchdog/iTCO_wdt.c
> +++ b/drivers/watchdog/iTCO_wdt.c
> @@ -106,6 +106,8 @@ struct iTCO_wdt_private {
>  	struct pci_dev *pci_dev;
>  	/* whether or not the watchdog has been suspended */
>  	bool suspended;
> +	/* no reboot update function pointer */
> +	int (*update_no_reboot_bit)(void *p, bool set);
>  };
>
>  /* module parameters */
> @@ -170,48 +172,61 @@ static inline u32 no_reboot_bit(struct iTCO_wdt_private *p)
>  	return enable_bit;
>  }
>
> -static void iTCO_wdt_set_NO_REBOOT_bit(struct iTCO_wdt_private *p)
> +static int update_no_reboot_bit_def(void *priv, bool set)
>  {
> -	u32 val32;
> -
> -	/* Set the NO_REBOOT bit: this disables reboots */
> -	if (p->iTCO_version >= 2) {
> -		val32 = readl(p->gcs_pmc);
> -		val32 |= no_reboot_bit(p);
> -		writel(val32, p->gcs_pmc);
> -	} else if (p->iTCO_version == 1) {
> -		pci_read_config_dword(p->pci_dev, 0xd4, &val32);
> -		val32 |= no_reboot_bit(p);
> -		pci_write_config_dword(p->pci_dev, 0xd4, val32);
> -	}
> +	return 0;
>  }
>
> -static int iTCO_wdt_unset_NO_REBOOT_bit(struct iTCO_wdt_private *p)
> +static int update_no_reboot_bit_pci(void *priv, bool set)
>  {
> -	u32 enable_bit = no_reboot_bit(p);
> -	u32 val32 = 0;
> +	struct iTCO_wdt_private *p = priv;
> +	u32 val32 = 0, newval32 = 0;
>
> -	/* Unset the NO_REBOOT bit: this enables reboots */
> -	if (p->iTCO_version >= 2) {
> -		val32 = readl(p->gcs_pmc);
> -		val32 &= ~enable_bit;
> -		writel(val32, p->gcs_pmc);
> +	pci_read_config_dword(p->pci_dev, 0xd4, &val32);
> +	if (set)
> +		val32 |= no_reboot_bit(p);
> +	else
> +		val32 &= ~no_reboot_bit(p);
> +	pci_write_config_dword(p->pci_dev, 0xd4, val32);
> +	pci_read_config_dword(p->pci_dev, 0xd4, &newval32);
>
> -		val32 = readl(p->gcs_pmc);
> -	} else if (p->iTCO_version == 1) {
> -		pci_read_config_dword(p->pci_dev, 0xd4, &val32);
> -		val32 &= ~enable_bit;
> -		pci_write_config_dword(p->pci_dev, 0xd4, val32);
> +	/* make sure the update is successful */
> +	if (val32 != newval32)
> +		return -EIO;
>
> -		pci_read_config_dword(p->pci_dev, 0xd4, &val32);
> -	}
> +	return 0;
> +}
> +
> +static int update_no_reboot_bit_mem(void *priv, bool set)
> +{
> +	struct iTCO_wdt_private *p = priv;
> +	u32 val32 = 0, newval32 = 0;
> +
> +	val32 = readl(p->gcs_pmc);
> +	if (set)
> +		val32 |= no_reboot_bit(p);
> +	else
> +		val32 &= ~no_reboot_bit(p);
> +	writel(val32, p->gcs_pmc);
> +	newval32 = readl(p->gcs_pmc);
>
> -	if (val32 & enable_bit)
> +	/* make sure the update is successful */
> +	if (val32 != newval32)
>  		return -EIO;
>
>  	return 0;
>  }
>
> +static void iTCO_wdt_no_reboot_bit_setup(struct iTCO_wdt_private *p)
> +{
> +	if (p->iTCO_version >= 2)
> +		p->update_no_reboot_bit = update_no_reboot_bit_mem;
> +	else if (p->iTCO_version == 1)
> +		p->update_no_reboot_bit = update_no_reboot_bit_pci;
> +	else
> +		p->update_no_reboot_bit = update_no_reboot_bit_def;
> +}
> +
>  static int iTCO_wdt_start(struct watchdog_device *wd_dev)
>  {
>  	struct iTCO_wdt_private *p = watchdog_get_drvdata(wd_dev);
> @@ -222,7 +237,7 @@ static int iTCO_wdt_start(struct watchdog_device *wd_dev)
>  	iTCO_vendor_pre_start(p->smi_res, wd_dev->timeout);
>
>  	/* disable chipset's NO_REBOOT bit */
> -	if (iTCO_wdt_unset_NO_REBOOT_bit(p)) {
> +	if (p->update_no_reboot_bit(p, false)) {
>  		spin_unlock(&p->io_lock);
>  		pr_err("failed to reset NO_REBOOT flag, reboot disabled by hardware/BIOS\n");
>  		return -EIO;
> @@ -263,7 +278,7 @@ static int iTCO_wdt_stop(struct watchdog_device *wd_dev)
>  	val = inw(TCO1_CNT(p));
>
>  	/* Set the NO_REBOOT bit to prevent later reboots, just for sure */
> -	iTCO_wdt_set_NO_REBOOT_bit(p);
> +	p->update_no_reboot_bit(p, true);
>
>  	spin_unlock(&p->io_lock);
>
> @@ -428,6 +443,8 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>  	p->iTCO_version = pdata->version;
>  	p->pci_dev = to_pci_dev(dev->parent);
>
> +	iTCO_wdt_no_reboot_bit_setup(p);
> +
>  	/*
>  	 * Get the Memory-Mapped GCS or PMC register, we need it for the
>  	 * NO_REBOOT flag (TCO v2 and v3).
> @@ -442,14 +459,14 @@ static int iTCO_wdt_probe(struct platform_device *pdev)
>  	}
>
>  	/* Check chipset's NO_REBOOT bit */
> -	if (iTCO_wdt_unset_NO_REBOOT_bit(p) &&
> +	if (p->update_no_reboot_bit(p, false) &&
>  	    iTCO_vendor_check_noreboot_on()) {
>  		pr_info("unable to reset NO_REBOOT flag, device disabled by hardware/BIOS\n");
>  		return -ENODEV;	/* Cannot reset NO_REBOOT bit */
>  	}
>
>  	/* Set the NO_REBOOT bit to prevent later reboots, just for sure */
> -	iTCO_wdt_set_NO_REBOOT_bit(p);
> +	p->update_no_reboot_bit(p, true);
>
>  	/* The TCO logic uses the TCO_EN bit in the SMI_EN register */
>  	if (!devm_request_region(dev, p->smi_res->start,