Re: [PATCH V2] mmc: sdhci: supporting PCI MSI

[Aaron Lu <aaron.lu@intel.com>]

On 11/12/2013 02:56 PM, Jackey Shen wrote:
> Enable MSI support in sdhci-pci driver and provide the mechanism
> to fall back to Legacy Pin-based Interrupt if MSI register fails.
> 
> Tested with SD cards on AMD platform.
> 

->

> Change from V1:
> - implement this PCI MSI feature in sdhci-pci.c instead of sdhci.c

Such words can be placed under the --- below so that it will not appear
in git log.

> 
> Signed-off-by: Jackey Shen <Jackey.Shen@amd.com>
> Reviewed-by: Huang Rui <ray.huang@amd.com>
> ---

->
Put change related info Here.

>  drivers/mmc/host/Kconfig     | 11 +++++++++
>  drivers/mmc/host/sdhci-pci.c | 58 ++++++++++++++++++++++++++++++++++++++++++++
>  drivers/mmc/host/sdhci.c     | 42 ++++++++++++++++++++++++++------
>  drivers/mmc/host/sdhci.h     |  2 ++
>  include/linux/mmc/sdhci.h    |  2 ++
>  5 files changed, 107 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
> index 7fc5099..a56cf27 100644
> --- a/drivers/mmc/host/Kconfig
> +++ b/drivers/mmc/host/Kconfig
> @@ -68,6 +68,17 @@ config MMC_SDHCI_PCI
>  
>  	  If unsure, say N.
>  
> +config MMC_SDHCI_PCI_MSI
> +	bool "SDHCI support with MSI on PCI bus"
> +	depends on MMC_SDHCI_PCI && PCI_MSI
> +	help
> +	  This enables PCI MSI (Message Signaled Interrupts) for Secure
> +	  Digital Host Controller Interface.
> +
> +	  If you have a controller with this capability, say Y or M here.
> +
> +	  If unsure, say N.
> +
>  config MMC_RICOH_MMC
>  	bool "Ricoh MMC Controller Disabler"
>  	depends on MMC_SDHCI_PCI
> diff --git a/drivers/mmc/host/sdhci-pci.c b/drivers/mmc/host/sdhci-pci.c
> index 8f75381..2ca29c0 100644
> --- a/drivers/mmc/host/sdhci-pci.c
> +++ b/drivers/mmc/host/sdhci-pci.c
> @@ -1143,10 +1143,68 @@ static void sdhci_pci_hw_reset(struct sdhci_host *host)
>  		slot->hw_reset(host);
>  }
>  
> +#ifdef CONFIG_MMC_SDHCI_PCI_MSI
> +static int sdhci_pci_setup_msi(struct sdhci_host *host, irq_handler_t handler)
> +{
> +	int ret;
> +	struct pci_dev *pdev = to_pci_dev(host->mmc->parent);
> +
> +	host->msi_enabled = false;
> +
> +	ret = pci_enable_msi(pdev);
> +	if (ret) {
> +		pr_warn("%s: Failed to allocate MSI entry\n",
> +			mmc_hostname(host->mmc));
> +		return ret;
> +	}
> +
> +	ret = request_irq(pdev->irq, handler, 0,
> +		mmc_hostname(host->mmc), host);
> +	if (ret) {
> +		pr_warn("%s: Failed to request MSI IRQ %d: %d\n",
> +		       mmc_hostname(host->mmc), pdev->irq, ret);
> +		pci_disable_msi(pdev);
> +		return ret;
> +	}
> +
> +	host->irq = pdev->irq;
> +	host->msi_enabled = true;
> +	return ret;
> +}

What about we only call pci_enable_msi in sdhci-pci.c and then assign
host->irq appropriately before calling sdhci_add_host, will that work?
The only difference would be, request_irq will have SHARED flag, but I
suppose that's not a problem.

> +
> +static int sdhci_pci_enable_msi(struct sdhci_host *host, irq_handler_t handler)
> +{
> +	return sdhci_pci_setup_msi(host, handler);
> +}
> +
> +static void sdhci_pci_disable_msi(struct sdhci_host *host)
> +{
> +	struct pci_dev *pdev = to_pci_dev(host->mmc->parent);
> +
> +	if (host->msi_enabled) {
> +		pci_disable_msi(pdev);
> +		host->msi_enabled = false;
> +	}
> +}
> +
> +#else
> +
> +static int sdhci_pci_enable_msi(struct sdhci_host *host, irq_handler_t handler)
> +{
> +	return 0;
> +}
> +
> +static void sdhci_pci_disable_msi(struct sdhci_host *host)
> +{
> +}
> +#endif /* CONFIG_MMC_SDHCI_PCI_MSI */
> +
>  static const struct sdhci_ops sdhci_pci_ops = {
>  	.enable_dma	= sdhci_pci_enable_dma,
>  	.platform_bus_width	= sdhci_pci_bus_width,
>  	.hw_reset		= sdhci_pci_hw_reset,
> +	.enable_msi		= sdhci_pci_enable_msi,
> +	.disable_msi		= sdhci_pci_disable_msi,
>  };
>  
>  /*****************************************************************************\
> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
> index 6785fb1..4c2a1ac 100644
> --- a/drivers/mmc/host/sdhci.c
> +++ b/drivers/mmc/host/sdhci.c
> @@ -2554,6 +2554,31 @@ void sdhci_disable_irq_wakeups(struct sdhci_host *host)
>  }
>  EXPORT_SYMBOL_GPL(sdhci_disable_irq_wakeups);
>  
> +static int sdhci_request_irq(struct sdhci_host *host)
> +{
> +	int ret = 0;
> +
> +	/* try to enable MSI */
> +	if (host->ops->enable_msi) {
> +		ret = host->ops->enable_msi(host, sdhci_irq);
> +		if (ret)
> +			pr_warn("%s: Fall back to Pin-based Interrupt: %d\n",
> +				mmc_hostname(host->mmc), ret);
> +	}
> +
> +	if (!host->msi_enabled) {
> +		/* fall back to legacy pin-based interrupt */
> +		ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
> +				mmc_hostname(host->mmc), host);
> +		if (ret) {
> +			pr_err("%s: Failed to request IRQ %d: %d\n",
> +				 mmc_hostname(host->mmc), host->irq, ret);
> +			return ret;
> +		}
> +	}
> +
> +	return ret;
> +}
>  int sdhci_suspend_host(struct sdhci_host *host)
>  {
>  	if (host->ops->platform_suspend)
> @@ -2570,6 +2595,8 @@ int sdhci_suspend_host(struct sdhci_host *host)
>  	if (!device_may_wakeup(mmc_dev(host->mmc))) {
>  		sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
>  		free_irq(host->irq, host);
> +		if (host->ops->disable_msi)
> +			host->ops->disable_msi(host);

What would happen if we do not disable/enable msi in suspend/resume host?
We have already masked all irqs with sdhci_mask_irqs anyway.

Thanks,
Aaron

>  	} else {
>  		sdhci_enable_irq_wakeups(host);
>  		enable_irq_wake(host->irq);
> @@ -2589,8 +2616,7 @@ int sdhci_resume_host(struct sdhci_host *host)
>  	}
>  
>  	if (!device_may_wakeup(mmc_dev(host->mmc))) {
> -		ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
> -				  mmc_hostname(host->mmc), host);
> +		ret = sdhci_request_irq(host);
>  		if (ret)
>  			return ret;
>  	} else {
> @@ -3212,13 +3238,9 @@ int sdhci_add_host(struct sdhci_host *host)
>  
>  	sdhci_init(host, 0);
>  
> -	ret = request_irq(host->irq, sdhci_irq, IRQF_SHARED,
> -		mmc_hostname(mmc), host);
> -	if (ret) {
> -		pr_err("%s: Failed to request IRQ %d: %d\n",
> -		       mmc_hostname(mmc), host->irq, ret);
> +	ret = sdhci_request_irq(host);
> +	if (ret)
>  		goto untasklet;
> -	}
>  
>  #ifdef CONFIG_MMC_DEBUG
>  	sdhci_dumpregs(host);
> @@ -3258,6 +3280,8 @@ reset:
>  	sdhci_reset(host, SDHCI_RESET_ALL);
>  	sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
>  	free_irq(host->irq, host);
> +	if (host->ops->disable_msi)
> +		host->ops->disable_msi(host);
>  #endif
>  untasklet:
>  	tasklet_kill(&host->card_tasklet);
> @@ -3301,6 +3325,8 @@ void sdhci_remove_host(struct sdhci_host *host, int dead)
>  
>  	sdhci_mask_irqs(host, SDHCI_INT_ALL_MASK);
>  	free_irq(host->irq, host);
> +	if (host->ops->disable_msi)
> +		host->ops->disable_msi(host);
>  
>  	del_timer_sync(&host->timer);
>  
> diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
> index 0a3ed01..cbee843 100644
> --- a/drivers/mmc/host/sdhci.h
> +++ b/drivers/mmc/host/sdhci.h
> @@ -296,6 +296,8 @@ struct sdhci_ops {
>  	void    (*adma_workaround)(struct sdhci_host *host, u32 intmask);
>  	void	(*platform_init)(struct sdhci_host *host);
>  	void    (*card_event)(struct sdhci_host *host);
> +	int	(*enable_msi)(struct sdhci_host *host, irq_handler_t handler);
> +	void	(*disable_msi)(struct sdhci_host *host);
>  };
>  
>  #ifdef CONFIG_MMC_SDHCI_IO_ACCESSORS
> diff --git a/include/linux/mmc/sdhci.h b/include/linux/mmc/sdhci.h
> index 3e781b8..3812479 100644
> --- a/include/linux/mmc/sdhci.h
> +++ b/include/linux/mmc/sdhci.h
> @@ -99,6 +99,8 @@ struct sdhci_host {
>  /* Controller has a non-standard host control register */
>  #define SDHCI_QUIRK2_BROKEN_HOST_CONTROL		(1<<5)
>  
> +	bool msi_enabled;	/* SD host controller with PCI MSI enabled */
> +
>  	int irq;		/* Device IRQ */
>  	void __iomem *ioaddr;	/* Mapped address */
>  
>