Re: [v8,4/7] PCI: mediatek-gen3: Add INTx support

[Jianjun Wang]

On Tue, 2021-03-09 at 11:10 +0000, Marc Zyngier wrote:
> On Wed, 24 Feb 2021 06:11:29 +0000,
> Jianjun Wang <jianjun.wang@xxxxxxxxxxxx> wrote:
> > 
> > Add INTx support for MediaTek Gen3 PCIe controller.
> > 
> > Signed-off-by: Jianjun Wang <jianjun.wang@xxxxxxxxxxxx>
> > Acked-by: Ryder Lee <ryder.lee@xxxxxxxxxxxx>
> > ---
> >  drivers/pci/controller/pcie-mediatek-gen3.c | 176 ++++++++++++++++++++
> >  1 file changed, 176 insertions(+)
> > 
> > diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
> > index c602beb9afec..8b3b5f838b69 100644
> > --- a/drivers/pci/controller/pcie-mediatek-gen3.c
> > +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
> > @@ -9,6 +9,9 @@
> >  #include <linux/clk.h>
> >  #include <linux/delay.h>
> >  #include <linux/iopoll.h>
> > +#include <linux/irq.h>
> > +#include <linux/irqchip/chained_irq.h>
> > +#include <linux/irqdomain.h>
> >  #include <linux/kernel.h>
> >  #include <linux/module.h>
> >  #include <linux/pci.h>
> > @@ -45,6 +48,13 @@
> >  #define PCIE_LINK_STATUS_REG		0x154
> >  #define PCIE_PORT_LINKUP		BIT(8)
> >  
> > +#define PCIE_INT_ENABLE_REG		0x180
> > +#define PCIE_INTX_SHIFT			24
> > +#define PCIE_INTX_ENABLE \
> > +	GENMASK(PCIE_INTX_SHIFT + PCI_NUM_INTX - 1, PCIE_INTX_SHIFT)
> > +
> > +#define PCIE_INT_STATUS_REG		0x184
> > +
> >  #define PCIE_TRANS_TABLE_BASE_REG	0x800
> >  #define PCIE_ATR_SRC_ADDR_MSB_OFFSET	0x4
> >  #define PCIE_ATR_TRSL_ADDR_LSB_OFFSET	0x8
> > @@ -73,6 +83,9 @@
> >   * @phy: PHY controller block
> >   * @clks: PCIe clocks
> >   * @num_clks: PCIe clocks count for this port
> > + * @irq: PCIe controller interrupt number
> > + * @irq_lock: lock protecting IRQ register access
> > + * @intx_domain: legacy INTx IRQ domain
> >   */
> >  struct mtk_pcie_port {
> >  	struct device *dev;
> > @@ -83,6 +96,10 @@ struct mtk_pcie_port {
> >  	struct phy *phy;
> >  	struct clk_bulk_data *clks;
> >  	int num_clks;
> > +
> > +	int irq;
> > +	raw_spinlock_t irq_lock;
> > +	struct irq_domain *intx_domain;
> >  };
> >  
> >  /**
> > @@ -199,6 +216,11 @@ static int mtk_pcie_startup_port(struct mtk_pcie_port *port)
> >  	val |= PCI_CLASS(PCI_CLASS_BRIDGE_PCI << 8);
> >  	writel_relaxed(val, port->base + PCIE_PCI_IDS_1);
> >  
> > +	/* Mask all INTx interrupts */
> > +	val = readl_relaxed(port->base + PCIE_INT_ENABLE_REG);
> > +	val &= ~PCIE_INTX_ENABLE;
> > +	writel_relaxed(val, port->base + PCIE_INT_ENABLE_REG);
> > +
> >  	/* Assert all reset signals */
> >  	val = readl_relaxed(port->base + PCIE_RST_CTRL_REG);
> >  	val |= PCIE_MAC_RSTB | PCIE_PHY_RSTB | PCIE_BRG_RSTB | PCIE_PE_RSTB;
> > @@ -262,6 +284,154 @@ static int mtk_pcie_startup_port(struct mtk_pcie_port *port)
> >  	return 0;
> >  }
> >  
> > +static int mtk_pcie_set_affinity(struct irq_data *data,
> > +				 const struct cpumask *mask, bool force)
> > +{
> > +	return -EINVAL;
> > +}
> > +
> > +static void mtk_intx_mask(struct irq_data *data)
> > +{
> > +	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
> > +	unsigned long flags;
> > +	u32 val;
> > +
> > +	raw_spin_lock_irqsave(&port->irq_lock, flags);
> > +	val = readl_relaxed(port->base + PCIE_INT_ENABLE_REG);
> > +	val &= ~BIT(data->hwirq + PCIE_INTX_SHIFT);
> > +	writel_relaxed(val, port->base + PCIE_INT_ENABLE_REG);
> > +	raw_spin_unlock_irqrestore(&port->irq_lock, flags);
> > +}
> > +
> > +static void mtk_intx_unmask(struct irq_data *data)
> > +{
> > +	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
> > +	unsigned long flags;
> > +	u32 val;
> > +
> > +	raw_spin_lock_irqsave(&port->irq_lock, flags);
> > +	val = readl_relaxed(port->base + PCIE_INT_ENABLE_REG);
> > +	val |= BIT(data->hwirq + PCIE_INTX_SHIFT);
> > +	writel_relaxed(val, port->base + PCIE_INT_ENABLE_REG);
> > +	raw_spin_unlock_irqrestore(&port->irq_lock, flags);
> > +}
> > +
> > +/**
> > + * mtk_intx_eoi
> > + * @data: pointer to chip specific data
> > + *
> > + * As an emulated level IRQ, its interrupt status will remain
> > + * until the corresponding de-assert message is received; hence that
> > + * the status can only be cleared when the interrupt has been serviced.
> > + */
> > +static void mtk_intx_eoi(struct irq_data *data)
> > +{
> > +	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
> > +	unsigned long hwirq;
> > +
> > +	hwirq = data->hwirq + PCIE_INTX_SHIFT;
> > +	writel_relaxed(BIT(hwirq), port->base + PCIE_INT_STATUS_REG);
> > +}
> > +
> > +static struct irq_chip mtk_intx_irq_chip = {
> > +	.irq_enable		= mtk_intx_unmask,
> > +	.irq_disable		= mtk_intx_mask,
> 
> Please get rid of enable/disable. Given that you already have
> mask/unmask with the *same* implementation, this offers zero benefit.

Hi Marc,

Thanks for your review.

We need to support suspend/resume feature, the HW will be powered off
when the system is suspended, and its register value will be cleared. If
the enable/disable callback is not implemented, the unmask function will
not be called when the system resume, so INTx will remain disabled.

Can I keep the enable/disable callback? Or do we have any solutions to
restore the register value when the system resume?

Thanks.
> 
> > +	.irq_mask		= mtk_intx_mask,
> > +	.irq_unmask		= mtk_intx_unmask,
> > +	.irq_eoi		= mtk_intx_eoi,
> > +	.irq_set_affinity	= mtk_pcie_set_affinity,
> > +	.name			= "INTx",
> > +};
> 
> [...]
> 
> Other that that, this look good to me.
> 
> Thanks,
> 
> 	M.
>