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Date:   Tue, 09 Mar 2021 11:23:05 +0000
Message-ID: <87pn08y3ja.wl-maz@kernel.org>
From:   Marc Zyngier <maz@kernel.org>
To:     Jianjun Wang <jianjun.wang@mediatek.com>
Cc:     Bjorn Helgaas <bhelgaas@google.com>,
        Rob Herring <robh+dt@kernel.org>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Ryder Lee <ryder.lee@mediatek.com>,
        Philipp Zabel <p.zabel@pengutronix.de>,
        Matthias Brugger <matthias.bgg@gmail.com>,
        <linux-pci@vger.kernel.org>, <linux-mediatek@lists.infradead.org>,
        <devicetree@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        <linux-arm-kernel@lists.infradead.org>,
        Sj Huang <sj.huang@mediatek.com>, <youlin.pei@mediatek.com>,
        <chuanjia.liu@mediatek.com>, <qizhong.cheng@mediatek.com>,
        <sin_jieyang@mediatek.com>, <drinkcat@chromium.org>,
        <Rex-BC.Chen@mediatek.com>, <anson.chuang@mediatek.com>
Subject: Re: [v8,5/7] PCI: mediatek-gen3: Add MSI support
In-Reply-To: <20210224061132.26526-6-jianjun.wang@mediatek.com>
References: <20210224061132.26526-1-jianjun.wang@mediatek.com>
        <20210224061132.26526-6-jianjun.wang@mediatek.com>
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On Wed, 24 Feb 2021 06:11:30 +0000,
Jianjun Wang <jianjun.wang@mediatek.com> wrote:
> 
> Add MSI support for MediaTek Gen3 PCIe controller.
> 
> This PCIe controller supports up to 256 MSI vectors, the MSI hardware
> block diagram is as follows:
> 
>                   +-----+
>                   | GIC |
>                   +-----+
>                      ^
>                      |
>                  port->irq
>                      |
>              +-+-+-+-+-+-+-+-+
>              |0|1|2|3|4|5|6|7| (PCIe intc)
>              +-+-+-+-+-+-+-+-+
>               ^ ^           ^
>               | |    ...    |
>       +-------+ +------+    +-----------+
>       |                |                |
> +-+-+---+--+--+  +-+-+---+--+--+  +-+-+---+--+--+
> |0|1|...|30|31|  |0|1|...|30|31|  |0|1|...|30|31| (MSI sets)
> +-+-+---+--+--+  +-+-+---+--+--+  +-+-+---+--+--+
>  ^ ^      ^  ^    ^ ^      ^  ^    ^ ^      ^  ^
>  | |      |  |    | |      |  |    | |      |  |  (MSI vectors)
>  | |      |  |    | |      |  |    | |      |  |
> 
>   (MSI SET0)       (MSI SET1)  ...   (MSI SET7)
> 
> With 256 MSI vectors supported, the MSI vectors are composed of 8 sets,
> each set has its own address for MSI message, and supports 32 MSI vectors
> to generate interrupt.
> 
> Signed-off-by: Jianjun Wang <jianjun.wang@mediatek.com>
> Acked-by: Ryder Lee <ryder.lee@mediatek.com>
> ---
>  drivers/pci/controller/pcie-mediatek-gen3.c | 277 ++++++++++++++++++++
>  1 file changed, 277 insertions(+)
> 
> diff --git a/drivers/pci/controller/pcie-mediatek-gen3.c b/drivers/pci/controller/pcie-mediatek-gen3.c
> index 8b3b5f838b69..3cbec22ece0c 100644
> --- a/drivers/pci/controller/pcie-mediatek-gen3.c
> +++ b/drivers/pci/controller/pcie-mediatek-gen3.c
> @@ -14,6 +14,7 @@
>  #include <linux/irqdomain.h>
>  #include <linux/kernel.h>
>  #include <linux/module.h>
> +#include <linux/msi.h>
>  #include <linux/pci.h>
>  #include <linux/phy/phy.h>
>  #include <linux/platform_device.h>
> @@ -48,12 +49,29 @@
>  #define PCIE_LINK_STATUS_REG		0x154
>  #define PCIE_PORT_LINKUP		BIT(8)
>  
> +#define PCIE_MSI_SET_NUM		8
> +#define PCIE_MSI_IRQS_PER_SET		32
> +#define PCIE_MSI_IRQS_NUM \
> +	(PCIE_MSI_IRQS_PER_SET * PCIE_MSI_SET_NUM)
> +
>  #define PCIE_INT_ENABLE_REG		0x180
> +#define PCIE_MSI_ENABLE			GENMASK(PCIE_MSI_SET_NUM + 8 - 1, 8)
> +#define PCIE_MSI_SHIFT			8
>  #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_MSI_SET_ENABLE_REG		0x190
> +#define PCIE_MSI_SET_ENABLE		GENMASK(PCIE_MSI_SET_NUM - 1, 0)
> +
> +#define PCIE_MSI_SET_BASE_REG		0xc00
> +#define PCIE_MSI_SET_OFFSET		0x10
> +#define PCIE_MSI_SET_STATUS_OFFSET	0x04
> +#define PCIE_MSI_SET_ENABLE_OFFSET	0x08
> +
> +#define PCIE_MSI_SET_ADDR_HI_BASE	0xc80
> +#define PCIE_MSI_SET_ADDR_HI_OFFSET	0x04
>  
>  #define PCIE_TRANS_TABLE_BASE_REG	0x800
>  #define PCIE_ATR_SRC_ADDR_MSB_OFFSET	0x4
> @@ -73,6 +91,16 @@
>  #define PCIE_ATR_TLP_TYPE_MEM		PCIE_ATR_TLP_TYPE(0)
>  #define PCIE_ATR_TLP_TYPE_IO		PCIE_ATR_TLP_TYPE(2)
>  
> +/**
> + * struct mtk_pcie_msi - MSI information for each set
> + * @base: IO mapped register base
> + * @msg_addr: MSI message address
> + */
> +struct mtk_msi_set {
> +	void __iomem *base;
> +	phys_addr_t msg_addr;
> +};
> +
>  /**
>   * struct mtk_pcie_port - PCIe port information
>   * @dev: pointer to PCIe device
> @@ -86,6 +114,11 @@
>   * @irq: PCIe controller interrupt number
>   * @irq_lock: lock protecting IRQ register access
>   * @intx_domain: legacy INTx IRQ domain
> + * @msi_domain: MSI IRQ domain
> + * @msi_bottom_domain: MSI IRQ bottom domain
> + * @msi_sets: MSI sets information
> + * @lock: lock protecting IRQ bit map
> + * @msi_irq_in_use: bit map for assigned MSI IRQ
>   */
>  struct mtk_pcie_port {
>  	struct device *dev;
> @@ -100,6 +133,11 @@ struct mtk_pcie_port {
>  	int irq;
>  	raw_spinlock_t irq_lock;
>  	struct irq_domain *intx_domain;
> +	struct irq_domain *msi_domain;
> +	struct irq_domain *msi_bottom_domain;
> +	struct mtk_msi_set msi_sets[PCIE_MSI_SET_NUM];
> +	struct mutex lock;
> +	DECLARE_BITMAP(msi_irq_in_use, PCIE_MSI_IRQS_NUM);
>  };
>  
>  /**
> @@ -197,6 +235,35 @@ static int mtk_pcie_set_trans_table(struct mtk_pcie_port *port,
>  	return 0;
>  }
>  
> +static void mtk_pcie_enable_msi(struct mtk_pcie_port *port)
> +{
> +	int i;
> +	u32 val;
> +
> +	val = readl_relaxed(port->base + PCIE_MSI_SET_ENABLE_REG);
> +	val |= PCIE_MSI_SET_ENABLE;
> +	writel_relaxed(val, port->base + PCIE_MSI_SET_ENABLE_REG);
> +
> +	val = readl_relaxed(port->base + PCIE_INT_ENABLE_REG);
> +	val |= PCIE_MSI_ENABLE;
> +	writel_relaxed(val, port->base + PCIE_INT_ENABLE_REG);

Shouldn't you configure the capture addresses *before* enabling
things? Is there any need for locking here, given that you are
modifying global registers?

> +
> +	for (i = 0; i < PCIE_MSI_SET_NUM; i++) {
> +		struct mtk_msi_set *msi_set = &port->msi_sets[i];
> +
> +		msi_set->base = port->base + PCIE_MSI_SET_BASE_REG +
> +				i * PCIE_MSI_SET_OFFSET;
> +		msi_set->msg_addr = port->reg_base + PCIE_MSI_SET_BASE_REG +
> +				    i * PCIE_MSI_SET_OFFSET;
> +
> +		/* Configure the MSI capture address */
> +		writel_relaxed(lower_32_bits(msi_set->msg_addr), msi_set->base);
> +		writel_relaxed(upper_32_bits(msi_set->msg_addr),
> +			       port->base + PCIE_MSI_SET_ADDR_HI_BASE +
> +			       i * PCIE_MSI_SET_ADDR_HI_OFFSET);
> +	}
> +}
> +
>  static int mtk_pcie_startup_port(struct mtk_pcie_port *port)
>  {
>  	struct resource_entry *entry;
> @@ -247,6 +314,8 @@ static int mtk_pcie_startup_port(struct mtk_pcie_port *port)
>  		return err;
>  	}
>  
> +	mtk_pcie_enable_msi(port);
> +
>  	/* Set PCIe translation windows */
>  	resource_list_for_each_entry(entry, &host->windows) {
>  		struct resource *res = entry->res;
> @@ -290,6 +359,148 @@ static int mtk_pcie_set_affinity(struct irq_data *data,
>  	return -EINVAL;
>  }
>  
> +static void mtk_pcie_irq_mask(struct irq_data *data)

It'd be good if you used _msi_ in function names that deal with MSIs.

> +{
> +	pci_msi_mask_irq(data);
> +	irq_chip_mask_parent(data);
> +}
> +
> +static void mtk_pcie_irq_unmask(struct irq_data *data)
> +{
> +	pci_msi_unmask_irq(data);
> +	irq_chip_unmask_parent(data);
> +}
> +
> +static struct irq_chip mtk_msi_irq_chip = {
> +	.name = "MSI",
> +	.irq_enable = mtk_pcie_irq_unmask,
> +	.irq_disable = mtk_pcie_irq_mask,

Same comment as for the previous patch: enable/disable serve no
purpose here.

> +	.irq_ack = irq_chip_ack_parent,
> +	.irq_mask = mtk_pcie_irq_mask,
> +	.irq_unmask = mtk_pcie_irq_unmask,
> +};
> +
> +static struct msi_domain_info mtk_msi_domain_info = {
> +	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_PCI_MSIX |
> +		   MSI_FLAG_USE_DEF_CHIP_OPS | MSI_FLAG_MULTI_PCI_MSI),

minor nit: keep the *_OPS flag on one line, and the *_PCI_* flags on
another.

> +	.chip	= &mtk_msi_irq_chip,
> +};
> +
> +static void mtk_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> +	struct mtk_msi_set *msi_set = irq_data_get_irq_chip_data(data);
> +	struct mtk_pcie_port *port = data->domain->host_data;
> +	unsigned long hwirq;
> +
> +	hwirq =	data->hwirq % PCIE_MSI_IRQS_PER_SET;
> +
> +	msg->address_hi = upper_32_bits(msi_set->msg_addr);
> +	msg->address_lo = lower_32_bits(msi_set->msg_addr);
> +	msg->data = hwirq;
> +	dev_dbg(port->dev, "msi#%#lx address_hi %#x address_lo %#x data %d\n",
> +		hwirq, msg->address_hi, msg->address_lo, msg->data);
> +}
> +
> +static void mtk_msi_bottom_irq_ack(struct irq_data *data)
> +{
> +	struct mtk_msi_set *msi_set = irq_data_get_irq_chip_data(data);
> +	unsigned long hwirq;
> +
> +	hwirq =	data->hwirq % PCIE_MSI_IRQS_PER_SET;
> +
> +	writel_relaxed(BIT(hwirq), msi_set->base + PCIE_MSI_SET_STATUS_OFFSET);
> +}
> +
> +static void mtk_msi_bottom_irq_mask(struct irq_data *data)
> +{
> +	struct mtk_msi_set *msi_set = irq_data_get_irq_chip_data(data);
> +	struct mtk_pcie_port *port = data->domain->host_data;
> +	unsigned long hwirq, flags;
> +	u32 val;
> +
> +	hwirq =	data->hwirq % PCIE_MSI_IRQS_PER_SET;
> +
> +	raw_spin_lock_irqsave(&port->irq_lock, flags);
> +	val = readl_relaxed(msi_set->base + PCIE_MSI_SET_ENABLE_OFFSET);
> +	val &= ~BIT(hwirq);
> +	writel_relaxed(val, msi_set->base + PCIE_MSI_SET_ENABLE_OFFSET);
> +	raw_spin_unlock_irqrestore(&port->irq_lock, flags);
> +}
> +
> +static void mtk_msi_bottom_irq_unmask(struct irq_data *data)
> +{
> +	struct mtk_msi_set *msi_set = irq_data_get_irq_chip_data(data);
> +	struct mtk_pcie_port *port = data->domain->host_data;
> +	unsigned long hwirq, flags;
> +	u32 val;
> +
> +	hwirq =	data->hwirq % PCIE_MSI_IRQS_PER_SET;
> +
> +	raw_spin_lock_irqsave(&port->irq_lock, flags);
> +	val = readl_relaxed(msi_set->base + PCIE_MSI_SET_ENABLE_OFFSET);
> +	val |= BIT(hwirq);
> +	writel_relaxed(val, msi_set->base + PCIE_MSI_SET_ENABLE_OFFSET);
> +	raw_spin_unlock_irqrestore(&port->irq_lock, flags);
> +}
> +
> +static struct irq_chip mtk_msi_bottom_irq_chip = {
> +	.irq_ack		= mtk_msi_bottom_irq_ack,
> +	.irq_mask		= mtk_msi_bottom_irq_mask,
> +	.irq_unmask		= mtk_msi_bottom_irq_unmask,
> +	.irq_compose_msi_msg	= mtk_compose_msi_msg,
> +	.irq_set_affinity	= mtk_pcie_set_affinity,
> +	.name			= "MSI",
> +};
> +
> +static int mtk_msi_bottom_domain_alloc(struct irq_domain *domain,
> +				       unsigned int virq, unsigned int nr_irqs,
> +				       void *arg)
> +{
> +	struct mtk_pcie_port *port = domain->host_data;
> +	struct mtk_msi_set *msi_set;
> +	int i, hwirq, set_idx;
> +
> +	mutex_lock(&port->lock);
> +
> +	hwirq = bitmap_find_free_region(port->msi_irq_in_use, PCIE_MSI_IRQS_NUM,
> +					order_base_2(nr_irqs));
> +
> +	mutex_unlock(&port->lock);
> +
> +	if (hwirq < 0)
> +		return -ENOSPC;
> +
> +	set_idx = hwirq / PCIE_MSI_IRQS_PER_SET;
> +	msi_set = &port->msi_sets[set_idx];
> +
> +	for (i = 0; i < nr_irqs; i++)
> +		irq_domain_set_info(domain, virq + i, hwirq + i,
> +				    &mtk_msi_bottom_irq_chip, msi_set,
> +				    handle_edge_irq, NULL, NULL);
> +
> +	return 0;
> +}
> +
> +static void mtk_msi_bottom_domain_free(struct irq_domain *domain,
> +				       unsigned int virq, unsigned int nr_irqs)
> +{
> +	struct mtk_pcie_port *port = domain->host_data;
> +	struct irq_data *data = irq_domain_get_irq_data(domain, virq);
> +
> +	mutex_lock(&port->lock);
> +
> +	bitmap_clear(port->msi_irq_in_use, data->hwirq, nr_irqs);
> +
> +	mutex_unlock(&port->lock);
> +
> +	irq_domain_free_irqs_common(domain, virq, nr_irqs);
> +}
> +
> +static const struct irq_domain_ops mtk_msi_bottom_domain_ops = {
> +	.alloc = mtk_msi_bottom_domain_alloc,
> +	.free = mtk_msi_bottom_domain_free,
> +};
> +
>  static void mtk_intx_mask(struct irq_data *data)
>  {
>  	struct mtk_pcie_port *port = irq_data_get_irq_chip_data(data);
> @@ -360,6 +571,7 @@ static int mtk_pcie_init_irq_domains(struct mtk_pcie_port *port)
>  {
>  	struct device *dev = port->dev;
>  	struct device_node *intc_node, *node = dev->of_node;
> +	int ret;
>  
>  	raw_spin_lock_init(&port->irq_lock);
>  
> @@ -377,7 +589,34 @@ static int mtk_pcie_init_irq_domains(struct mtk_pcie_port *port)
>  		return -ENODEV;
>  	}
>  
> +	/* Setup MSI */
> +	mutex_init(&port->lock);
> +
> +	port->msi_bottom_domain = irq_domain_add_linear(node, PCIE_MSI_IRQS_NUM,
> +				  &mtk_msi_bottom_domain_ops, port);
> +	if (!port->msi_bottom_domain) {
> +		dev_info(dev, "failed to create MSI bottom domain\n");
> +		ret = -ENODEV;
> +		goto err_msi_bottom_domain;
> +	}
> +
> +	port->msi_domain = pci_msi_create_irq_domain(dev->fwnode,
> +						     &mtk_msi_domain_info,
> +						     port->msi_bottom_domain);
> +	if (!port->msi_domain) {
> +		dev_info(dev, "failed to create MSI domain\n");
> +		ret = -ENODEV;
> +		goto err_msi_domain;
> +	}
> +
>  	return 0;
> +
> +err_msi_domain:
> +	irq_domain_remove(port->msi_bottom_domain);
> +err_msi_bottom_domain:
> +	irq_domain_remove(port->intx_domain);
> +
> +	return ret;
>  }
>  
>  static void mtk_pcie_irq_teardown(struct mtk_pcie_port *port)
> @@ -387,9 +626,39 @@ static void mtk_pcie_irq_teardown(struct mtk_pcie_port *port)
>  	if (port->intx_domain)
>  		irq_domain_remove(port->intx_domain);
>  
> +	if (port->msi_domain)
> +		irq_domain_remove(port->msi_domain);
> +
> +	if (port->msi_bottom_domain)
> +		irq_domain_remove(port->msi_bottom_domain);
> +
>  	irq_dispose_mapping(port->irq);
>  }
>  
> +static void mtk_pcie_msi_handler(struct mtk_pcie_port *port, int set_idx)
> +{
> +	struct mtk_msi_set *msi_set = &port->msi_sets[set_idx];
> +	unsigned long msi_enable, msi_status;
> +	unsigned int virq;
> +	irq_hw_number_t bit, hwirq;
> +
> +	msi_enable = readl_relaxed(msi_set->base + PCIE_MSI_SET_ENABLE_OFFSET);
> +
> +	do {
> +		msi_status = readl_relaxed(msi_set->base +
> +					   PCIE_MSI_SET_STATUS_OFFSET);
> +		msi_status &= msi_enable;
> +		if (!msi_status)
> +			break;
> +
> +		for_each_set_bit(bit, &msi_status, PCIE_MSI_IRQS_PER_SET) {
> +			hwirq = bit + set_idx * PCIE_MSI_IRQS_PER_SET;
> +			virq = irq_find_mapping(port->msi_bottom_domain, hwirq);
> +			generic_handle_irq(virq);
> +		}
> +	} while (true);
> +}
> +
>  static void mtk_pcie_irq_handler(struct irq_desc *desc)
>  {
>  	struct mtk_pcie_port *port = irq_desc_get_handler_data(desc);
> @@ -408,6 +677,14 @@ static void mtk_pcie_irq_handler(struct irq_desc *desc)
>  		generic_handle_irq(virq);
>  	}
>  
> +	irq_bit = PCIE_MSI_SHIFT;
> +	for_each_set_bit_from(irq_bit, &status, PCIE_MSI_SET_NUM +
> +			      PCIE_MSI_SHIFT) {
> +		mtk_pcie_msi_handler(port, irq_bit - PCIE_MSI_SHIFT);
> +
> +		writel_relaxed(BIT(irq_bit), port->base + PCIE_INT_STATUS_REG);

Isn't this write the same thing you have for EOI in the INTx case?
While I could understand your description in that case (this is a
resampling operation), I don't get what this does here. Either this is
also an EOI, but your initial description doesn't make sense, or it is
an Ack, and it should be moved to the right place.

Which one is it?

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.