Message-ID: <123724a33c29d1f078f2a65795c6e208@kernel.org>
Date:   Tue, 26 Jan 2021 12:25:08 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     Jianjun Wang <jianjun.wang@...iatek.com>
Cc:     Bjorn Helgaas <bhelgaas@...gle.com>,
        Rob Herring <robh+dt@...nel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Ryder Lee <ryder.lee@...iatek.com>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        Matthias Brugger <matthias.bgg@...il.com>,
        linux-pci@...r.kernel.org, linux-mediatek@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Sj Huang <sj.huang@...iatek.com>, youlin.pei@...iatek.com,
        chuanjia.liu@...iatek.com, qizhong.cheng@...iatek.com,
        sin_jieyang@...iatek.com, drinkcat@...omium.org,
        Rex-BC.Chen@...iatek.com, anson.chuang@...iatek.com
Subject: Re: [v7,4/7] PCI: mediatek-gen3: Add INTx support

On 2021-01-13 11:39, Jianjun Wang wrote:
> Add INTx support for MediaTek Gen3 PCIe controller.
> 
> Signed-off-by: Jianjun Wang <jianjun.wang@...iatek.com>
> Acked-by: Ryder Lee <ryder.lee@...iatek.com>
> ---
>  drivers/pci/controller/pcie-mediatek-gen3.c | 163 ++++++++++++++++++++
>  1 file changed, 163 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c
> b/drivers/pci/controller/pcie-mediatek-gen3.c
> index c00ea7c167de..7979a2856c35 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/of_address.h>
> @@ -49,6 +52,12 @@
>  #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_MASK			GENMASK(27, 24)

I guess this '24' is actually PCIE_INTX_SHIFT? In this case,
please write it as

GENMASK(PCIE_INTX_SHIFT + PCI_NUM_INTX - 1, PCIE_INTX_SHIFT)

to make it clear that you are dealing with one bit per INTx.

> +
> +#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
> @@ -77,6 +86,8 @@
>   * @phy: PHY controller block
>   * @clks: PCIe clocks
>   * @num_clks: PCIe clocks count for this port
> + * @irq: PCIe controller interrupt number
> + * @intx_domain: legacy INTx IRQ domain
>   */
>  struct mtk_pcie_port {
>  	struct device *dev;
> @@ -87,6 +98,9 @@ struct mtk_pcie_port {
>  	struct phy *phy;
>  	struct clk_bulk_data *clks;
>  	int num_clks;
> +
> +	int irq;
> +	struct irq_domain *intx_domain;
>  };
> 
>  /**
> @@ -266,6 +280,149 @@ 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);
> +	u32 val;
> +
> +	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);

This is missing some locking. Otherwise, two concurrent mask/unmask
for different interrupts will corrupt each other's state.

> +}
> +
> +static void mtk_intx_unmask(struct irq_data *data)
> +{
> +	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
> +	u32 val;
> +
> +	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);

Same thing here.

> +}
> +
> +/**
> + * 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_mask		= mtk_intx_mask,
> +	.irq_unmask		= mtk_intx_unmask,
> +	.irq_eoi		= mtk_intx_eoi,
> +	.irq_set_affinity	= mtk_pcie_set_affinity,
> +	.name			= "PCIe",

nit: "PCIe" is not really descriptive. "INTx" would be a bit better.

> +};
> +
> +static int mtk_pcie_intx_map(struct irq_domain *domain, unsigned int 
> irq,
> +			     irq_hw_number_t hwirq)
> +{
> +	irq_set_chip_and_handler_name(irq, &mtk_intx_irq_chip,
> +				      handle_fasteoi_irq, "INTx");
> +	irq_set_chip_data(irq, domain->host_data);

You probably want to set the chip_data *before* wiring
the handler, as otherwise you could end-up with a NULL
pointer in any of the callbacks if the interrupt fires
between the two.

> +
> +	return 0;
> +}
> +
> +static const struct irq_domain_ops intx_domain_ops = {
> +	.map = mtk_pcie_intx_map,
> +};
> +
> +static int mtk_pcie_init_irq_domains(struct mtk_pcie_port *port,
> +				     struct device_node *node)
> +{
> +	struct device *dev = port->dev;
> +	struct device_node *intc_node;
> +
> +	/* Setup INTx */
> +	intc_node = of_get_child_by_name(node, "interrupt-controller");
> +	if (!intc_node) {
> +		dev_err(dev, "missing PCIe Intc node\n");
> +		return -ENODEV;
> +	}
> +
> +	port->intx_domain = irq_domain_add_linear(intc_node, PCI_NUM_INTX,
> +						  &intx_domain_ops, port);
> +	if (!port->intx_domain) {
> +		dev_err(dev, "failed to get INTx IRQ domain\n");
> +		return -ENODEV;
> +	}
> +
> +	return 0;
> +}
> +
> +static void mtk_pcie_irq_teardown(struct mtk_pcie_port *port)
> +{
> +	irq_set_chained_handler_and_data(port->irq, NULL, NULL);
> +
> +	if (port->intx_domain)
> +		irq_domain_remove(port->intx_domain);
> +
> +	irq_dispose_mapping(port->irq);
> +}
> +
> +static void mtk_pcie_irq_handler(struct irq_desc *desc)
> +{
> +	struct mtk_pcie_port *port = irq_desc_get_handler_data(desc);
> +	struct irq_chip *irqchip = irq_desc_get_chip(desc);
> +	unsigned long status;
> +	unsigned int virq;
> +	irq_hw_number_t irq_bit = PCIE_INTX_SHIFT;
> +
> +	chained_irq_enter(irqchip, desc);
> +
> +	status = readl_relaxed(port->base + PCIE_INT_STATUS_REG);
> +	if (status & PCIE_INTX_MASK) {

This "if (status & PCIE_INTX_MASK)" is already implicit from
the for_each_set_bit_from() iterator, and you can drop it.

> +		for_each_set_bit_from(irq_bit, &status, PCI_NUM_INTX +
> +				      PCIE_INTX_SHIFT) {
> +			virq = irq_find_mapping(port->intx_domain,
> +						irq_bit - PCIE_INTX_SHIFT);
> +			generic_handle_irq(virq);
> +		}
> +	}
> +
> +	chained_irq_exit(irqchip, desc);
> +}
> +
> +static int mtk_pcie_setup_irq(struct mtk_pcie_port *port,
> +			      struct device_node *node)
> +{
> +	struct device *dev = port->dev;
> +	struct platform_device *pdev = to_platform_device(dev);
> +	int err;
> +
> +	err = mtk_pcie_init_irq_domains(port, node);
> +	if (err) {
> +		dev_err(dev, "failed to init PCIe IRQ domain\n");
> +		return err;
> +	}
> +
> +	port->irq = platform_get_irq(pdev, 0);
> +	if (port->irq < 0)
> +		return port->irq;
> +
> +	irq_set_chained_handler_and_data(port->irq, mtk_pcie_irq_handler, 
> port);

You seem to be missing something that will mask all INTx interrupts
as an initial state.

> +
> +	return 0;
> +}
> +
>  static int mtk_pcie_clk_init(struct mtk_pcie_port *port)
>  {
>  	int ret;
> @@ -388,6 +545,10 @@ static int mtk_pcie_setup(struct mtk_pcie_port 
> *port)
>  		goto err_setup;
>  	}
> 
> +	err = mtk_pcie_setup_irq(port, dev->of_node);
> +	if (err)
> +		goto err_setup;
> +
>  	dev_info(dev, "PCIe link up success!\n");
> 
>  	return 0;
> @@ -423,6 +584,7 @@ static int mtk_pcie_probe(struct platform_device 
> *pdev)
> 
>  	err = pci_host_probe(host);
>  	if (err) {
> +		mtk_pcie_irq_teardown(port);
>  		mtk_pcie_power_down(port);
>  		return err;
>  	}
> @@ -440,6 +602,7 @@ static int mtk_pcie_remove(struct platform_device 
> *pdev)
>  	pci_remove_root_bus(host->bus);
>  	pci_unlock_rescan_remove();
> 
> +	mtk_pcie_irq_teardown(port);
>  	mtk_pcie_power_down(port);
> 
>  	return 0;

Thanks,

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

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