linux-kernel - Re: [PATCH v6 3/3] PCI: Add tango MSI controller support

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Date:   Tue, 13 Jun 2017 15:22:39 +0100
From:   Marc Zyngier <marc.zyngier@....com>
To:     Marc Gonzalez <marc_gonzalez@...madesigns.com>,
        Thomas Gleixner <tglx@...utronix.de>
Cc:     Bjorn Helgaas <helgaas@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Liviu Dudau <liviu.dudau@....com>,
        David Laight <david.laight@...lab.com>,
        linux-pci <linux-pci@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>, Mason <slash.tmp@...e.fr>
Subject: Re: [PATCH v6 3/3] PCI: Add tango MSI controller support

On 13/06/17 15:01, Marc Gonzalez wrote:
> The MSI controller in Tango supports 256 message-signaled interrupts,
> and a single doorbell address.
> 
> Signed-off-by: Marc Gonzalez <marc_gonzalez@...madesigns.com>
> ---
> Changes from v5 to v6
> o Rename 'used' bitmap to 'used_msi'
> o Rename 'lock' spinlock to 'used_msi_lock'
> o Take lock in interrupt handler
> o Remove irq_dom in error path
> ---
>  drivers/pci/host/pcie-tango.c | 225 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 225 insertions(+)
> 
> diff --git a/drivers/pci/host/pcie-tango.c b/drivers/pci/host/pcie-tango.c
> index 67aaadcc1c5e..b06446b23bc8 100644
> --- a/drivers/pci/host/pcie-tango.c
> +++ b/drivers/pci/host/pcie-tango.c
> @@ -1,16 +1,228 @@
> +#include <linux/irqchip/chained_irq.h>
> +#include <linux/irqdomain.h>
>  #include <linux/pci-ecam.h>
>  #include <linux/delay.h>
> +#include <linux/msi.h>
>  #include <linux/of.h>
>  
>  #define MSI_MAX 256
>  
>  #define SMP8759_MUX		0x48
>  #define SMP8759_TEST_OUT	0x74
> +#define SMP8759_STATUS		0x80
> +#define SMP8759_ENABLE		0xa0
> +#define SMP8759_DOORBELL	0xa002e07c
>  
>  struct tango_pcie {
> +	DECLARE_BITMAP(used_msi, MSI_MAX);
> +	spinlock_t used_msi_lock;
>  	void __iomem *mux;
> +	void __iomem *msi_status;
> +	void __iomem *msi_enable;
> +	phys_addr_t msi_doorbell;
> +	struct irq_domain *irq_dom;
> +	struct irq_domain *msi_dom;
> +	int irq;
>  };
>  
> +/*** MSI CONTROLLER SUPPORT ***/
> +
> +static void tango_msi_isr(struct irq_desc *desc)
> +{
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	struct tango_pcie *pcie = irq_desc_get_handler_data(desc);
> +	unsigned long flags, status, base, virq, idx, pos = 0;
> +
> +	chained_irq_enter(chip, desc);
> +	spin_lock_irqsave(&pcie->used_msi_lock, flags);

You're already in interrupt context, so there is no need to disable
interrupts any further. spin_lock() should do the trick

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...