Re: [PATCH v6 1/9] PCI: dwc: Add IRQ chained API support

[Marc Zyngier <marc.zyngier@arm.com>]

Hi Gustavo,

On 26/01/18 16:35, Gustavo Pimentel wrote:
> Adds a IRQ chained API to pcie-designware, that aims to replace the current
> IRQ domain hierarchy API implemented.
> 
> Although the IRQ domain hierarchy API is still available, pcie-designware
> will use now the IRQ chained API.

I'm a bit thrown by this comment, as I don't think it reflects the
reality of the code.

What you have here is a domain hierarchy (generic PCI MSI layer and HW
specific domain), *and* a multiplexer (chained interrupt) that funnels
all your MSIs into a single parent interrupt. What you're moving away
from is the msi_controller API.

This has no impact on the code, but it helps to use the correct terminology.

> 
> Signed-off-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>
> Tested-by: Niklas Cassel <niklas.cassel@axis.com>
> ---
> Change v1->v2:
> - num_vectors is now not configurable by the Device Tree. Now it is 32 by
> default and can be overridden by any specific SoC driver.
> Change v2->v3:
> - Nothing changed, just to follow the patch set version.
> Change v3->v4:
> - Moved Kishon's fixes (PCI end point error and a dra7xx warning) from
> v3-0007 patch file to here.
> - Undo the change of the function signature to be more coherent with the
> host mode specific functions (Thanks Kishon).
> - Refactor the added functions in order to used host_data so that getting
> pp again back from pci could be avoided. (Thanks Kishon)
> - Changed summary line to match the drivers/PCI convention and changelog to
> maintain the consistency (thanks Bjorn).
> Change v4->v5:
> - Implemented Kishon MSI multiple messages fix (thanks Kishon).
> Change v5->v6:
> - Fixed rebase problem detected by Niklas (thanks Niklas).
> 
>  drivers/pci/dwc/pcie-designware-host.c | 296 +++++++++++++++++++++++++++++----
>  drivers/pci/dwc/pcie-designware.h      |  18 ++
>  2 files changed, 286 insertions(+), 28 deletions(-)
> 
> diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c
> index bf558df..f7b2bce 100644
> --- a/drivers/pci/dwc/pcie-designware-host.c
> +++ b/drivers/pci/dwc/pcie-designware-host.c
> @@ -11,6 +11,7 @@
>   * published by the Free Software Foundation.
>   */
>  
> +#include <linux/irqchip/chained_irq.h>
>  #include <linux/irqdomain.h>
>  #include <linux/of_address.h>
>  #include <linux/of_pci.h>
> @@ -53,6 +54,36 @@ static struct irq_chip dw_msi_irq_chip = {
>  	.irq_unmask = pci_msi_unmask_irq,
>  };
>  
> +static void dw_msi_ack_irq(struct irq_data *d)
> +{
> +	irq_chip_ack_parent(d);
> +}
> +
> +static void dw_msi_mask_irq(struct irq_data *d)
> +{
> +	pci_msi_mask_irq(d);
> +	irq_chip_mask_parent(d);
> +}
> +
> +static void dw_msi_unmask_irq(struct irq_data *d)
> +{
> +	pci_msi_unmask_irq(d);
> +	irq_chip_unmask_parent(d);
> +}
> +
> +static struct irq_chip dw_pcie_msi_irq_chip = {
> +	.name = "PCI-MSI",
> +	.irq_ack = dw_msi_ack_irq,
> +	.irq_mask = dw_msi_mask_irq,
> +	.irq_unmask = dw_msi_unmask_irq,
> +};
> +
> +static struct msi_domain_info dw_pcie_msi_domain_info = {
> +	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
> +		   MSI_FLAG_PCI_MSIX | MSI_FLAG_MULTI_PCI_MSI),
> +	.chip	= &dw_pcie_msi_irq_chip,
> +};
> +
>  /* MSI int handler */
>  irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
>  {
> @@ -81,6 +112,196 @@ irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
>  	return ret;
>  }
>  
> +/* Chained MSI interrupt service routine */
> +static void dw_chained_msi_isr(struct irq_desc *desc)
> +{
> +	struct irq_chip *chip = irq_desc_get_chip(desc);
> +	struct pcie_port *pp;
> +
> +	chained_irq_enter(chip, desc);
> +
> +	pp = irq_desc_get_handler_data(desc);
> +	dw_handle_msi_irq(pp);
> +
> +	chained_irq_exit(chip, desc);
> +}

Nit: once you're done with the msi_controller stuff (in patch #8), it'd
be good to move dw_handle_msi_irq() inside this function, as the
irqreturn_t return type doesn't make much sense any more.

> +
> +static void dw_pci_setup_msi_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> +	struct pcie_port *pp = irq_data_get_irq_chip_data(data);
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	u64 msi_target;
> +
> +	if (pp->ops->get_msi_addr)
> +		msi_target = pp->ops->get_msi_addr(pp);
> +	else
> +		msi_target = (u64)pp->msi_data;
> +
> +	msg->address_lo = lower_32_bits(msi_target);
> +	msg->address_hi = upper_32_bits(msi_target);
> +
> +	if (pp->ops->get_msi_data)
> +		msg->data = pp->ops->get_msi_data(pp, data->hwirq);
> +	else
> +		msg->data = data->hwirq;
> +
> +	dev_dbg(pci->dev, "msi#%d address_hi %#x address_lo %#x\n",
> +		(int)data->hwirq, msg->address_hi, msg->address_lo);
> +}
> +
> +static int dw_pci_msi_set_affinity(struct irq_data *irq_data,
> +				   const struct cpumask *mask, bool force)
> +{
> +	return -EINVAL;
> +}
> +
> +static void dw_pci_bottom_mask(struct irq_data *data)
> +{
> +	struct pcie_port *pp = irq_data_get_irq_chip_data(data);
> +	unsigned int res, bit, ctrl;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pp->lock, flags);

Consider turning this lock (and the corresponding locking primitives) to
a raw spin_lock. This won't have any additional effect for the mainline
kernel, but will make it work correctly if you use the RT patches.

> +
> +	if (pp->ops->msi_clear_irq)
> +		pp->ops->msi_clear_irq(pp, data->hwirq);
> +	else {

Please use { } on both sides of the else.

> +		ctrl = data->hwirq / 32;
> +		res = ctrl * 12;
> +		bit = data->hwirq % 32;
> +
> +		pp->irq_status[ctrl] &= ~(1 << bit);
> +		dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4,
> +				    pp->irq_status[ctrl]);
> +	}
> +
> +	spin_unlock_irqrestore(&pp->lock, flags);
> +}
> +
> +static void dw_pci_bottom_unmask(struct irq_data *data)
> +{
> +	struct pcie_port *pp = irq_data_get_irq_chip_data(data);
> +	unsigned int res, bit, ctrl;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pp->lock, flags);
> +
> +	if (pp->ops->msi_set_irq)
> +		pp->ops->msi_set_irq(pp, data->hwirq);
> +	else {
> +		ctrl = data->hwirq / 32;
> +		res = ctrl * 12;
> +		bit = data->hwirq % 32;
> +
> +		pp->irq_status[ctrl] |= 1 << bit;
> +		dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4,
> +				    pp->irq_status[ctrl]);
> +	}
> +
> +	spin_unlock_irqrestore(&pp->lock, flags);
> +}
> +
> +static void dw_pci_bottom_ack(struct irq_data *d)
> +{
> +	struct msi_desc *msi = irq_data_get_msi_desc(d);
> +	struct pcie_port *pp;
> +
> +	pp = (struct pcie_port *) msi_desc_to_pci_sysdata(msi);

msi_desc_to_pci_sysdata returns a void*, so you can remove this cast.

> +
> +	if (pp->ops->msi_irq_ack)
> +		pp->ops->msi_irq_ack(d->hwirq, pp);
> +}
> +
> +static struct irq_chip dw_pci_msi_bottom_irq_chip = {
> +	.name = "DWPCI-MSI",
> +	.irq_ack = dw_pci_bottom_ack,
> +	.irq_compose_msi_msg = dw_pci_setup_msi_msg,
> +	.irq_set_affinity = dw_pci_msi_set_affinity,
> +	.irq_mask = dw_pci_bottom_mask,
> +	.irq_unmask = dw_pci_bottom_unmask,
> +};
> +
> +static int dw_pcie_irq_domain_alloc(struct irq_domain *domain,
> +				    unsigned int virq, unsigned int nr_irqs,
> +				    void *args)
> +{
> +	struct pcie_port *pp = domain->host_data;
> +	unsigned long flags;
> +	unsigned long bit;
> +	u32 i;
> +
> +	spin_lock_irqsave(&pp->lock, flags);
> +
> +	bit = bitmap_find_free_region(pp->msi_irq_in_use, pp->num_vectors,
> +				      order_base_2(nr_irqs));
> +
> +	if (bit < 0) {
> +		spin_unlock_irqrestore(&pp->lock, flags);
> +		return -ENOSPC;
> +	}
> +
> +	spin_unlock_irqrestore(&pp->lock, flags);
> +
> +	for (i = 0; i < nr_irqs; i++)
> +		irq_domain_set_info(domain, virq + i, bit + i,
> +				    &dw_pci_msi_bottom_irq_chip,
> +				    pp, handle_level_irq,

Are you sure about this "handle_level_irq"? MSIs are definitely edge
triggered, not level.

> +				    NULL, NULL);
> +
> +	return 0;
> +}
> +
> +static void dw_pcie_irq_domain_free(struct irq_domain *domain,
> +				    unsigned int virq, unsigned int nr_irqs)
> +{
> +	struct irq_data *data = irq_domain_get_irq_data(domain, virq);
> +	struct pcie_port *pp = irq_data_get_irq_chip_data(data);
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pp->lock, flags);
> +	bitmap_release_region(pp->msi_irq_in_use, data->hwirq,
> +			      order_base_2(nr_irqs));
> +	spin_unlock_irqrestore(&pp->lock, flags);
> +}
> +
> +static const struct irq_domain_ops dw_pcie_msi_domain_ops = {
> +	.alloc	= dw_pcie_irq_domain_alloc,
> +	.free	= dw_pcie_irq_domain_free,
> +};
> +
> +int dw_pcie_allocate_domains(struct pcie_port *pp)
> +{
> +	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> +	struct fwnode_handle *fwnode = of_node_to_fwnode(pci->dev->of_node);
> +
> +	pp->irq_domain = irq_domain_create_linear(fwnode, pp->num_vectors,
> +					       &dw_pcie_msi_domain_ops, pp);
> +	if (!pp->irq_domain) {
> +		dev_err(pci->dev, "failed to create IRQ domain\n");
> +		return -ENOMEM;
> +	}
> +
> +	pp->msi_domain = pci_msi_create_irq_domain(fwnode,
> +						   &dw_pcie_msi_domain_info,
> +						   pp->irq_domain);
> +	if (!pp->msi_domain) {
> +		dev_err(pci->dev, "failed to create MSI domain\n");
> +		irq_domain_remove(pp->irq_domain);
> +		return -ENOMEM;
> +	}
> +
> +	return 0;
> +}
> +
> +void dw_pcie_free_msi(struct pcie_port *pp)
> +{
> +	irq_set_chained_handler(pp->msi_irq, NULL);
> +	irq_set_handler_data(pp->msi_irq, NULL);
> +
> +	irq_domain_remove(pp->msi_domain);
> +	irq_domain_remove(pp->irq_domain);
> +}
> +
>  void dw_pcie_msi_init(struct pcie_port *pp)
>  {
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
> @@ -99,20 +320,21 @@ void dw_pcie_msi_init(struct pcie_port *pp)
>  
>  	/* program the msi_data */
>  	dw_pcie_wr_own_conf(pp, PCIE_MSI_ADDR_LO, 4,
> -			    (u32)(msi_target & 0xffffffff));
> +			    lower_32_bits(msi_target));
>  	dw_pcie_wr_own_conf(pp, PCIE_MSI_ADDR_HI, 4,
> -			    (u32)(msi_target >> 32 & 0xffffffff));
> +			    upper_32_bits(msi_target));
>  }
>  
>  static void dw_pcie_msi_clear_irq(struct pcie_port *pp, int irq)
>  {
> -	unsigned int res, bit, val;
> +	unsigned int res, bit, ctrl;
>  
> -	res = (irq / 32) * 12;
> +	ctrl = irq / 32;
> +	res = ctrl * 12;
>  	bit = irq % 32;
> -	dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4, &val);
> -	val &= ~(1 << bit);
> -	dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4, val);
> +	pp->irq_status[ctrl] &= ~(1 << bit);
> +	dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4,
> +			    pp->irq_status[ctrl]);
>  }
>  
>  static void clear_irq_range(struct pcie_port *pp, unsigned int irq_base,
> @@ -134,13 +356,14 @@ static void clear_irq_range(struct pcie_port *pp, unsigned int irq_base,
>  
>  static void dw_pcie_msi_set_irq(struct pcie_port *pp, int irq)
>  {
> -	unsigned int res, bit, val;
> +	unsigned int res, bit, ctrl;
>  
> -	res = (irq / 32) * 12;
> +	ctrl = irq / 32;
> +	res = ctrl * 12;
>  	bit = irq % 32;
> -	dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4, &val);
> -	val |= 1 << bit;
> -	dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4, val);
> +	pp->irq_status[ctrl] |= 1 << bit;
> +	dw_pcie_wr_own_conf(pp, PCIE_MSI_INTR0_ENABLE + res, 4,
> +			    pp->irq_status[ctrl]);
>  }
>  
>  static int assign_irq(int no_irqs, struct msi_desc *desc, int *pos)
> @@ -288,11 +511,13 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  	struct device *dev = pci->dev;
>  	struct device_node *np = dev->of_node;
>  	struct platform_device *pdev = to_platform_device(dev);
> +	struct resource_entry *win, *tmp;
>  	struct pci_bus *bus, *child;
>  	struct pci_host_bridge *bridge;
>  	struct resource *cfg_res;
> -	int i, ret;
> -	struct resource_entry *win, *tmp;
> +	int ret;
> +
> +	spin_lock_init(&pci->pp.lock);
>  
>  	cfg_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config");
>  	if (cfg_res) {
> @@ -391,18 +616,33 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  		pci->num_viewport = 2;
>  
>  	if (IS_ENABLED(CONFIG_PCI_MSI)) {
> -		if (!pp->ops->msi_host_init) {
> -			pp->irq_domain = irq_domain_add_linear(dev->of_node,
> -						MAX_MSI_IRQS, &msi_domain_ops,
> -						&dw_pcie_msi_chip);
> -			if (!pp->irq_domain) {
> -				dev_err(dev, "irq domain init failed\n");
> -				ret = -ENXIO;
> +		/*
> +		 * If a specific SoC driver needs to change the
> +		 * default number of vectors, it needs to implement
> +		 * the set_num_vectors callback.
> +		 */
> +		if (!pp->ops->set_num_vectors) {
> +			pp->num_vectors = MSI_DEF_NUM_VECTORS;
> +		} else {
> +			pp->ops->set_num_vectors(pp);
> +
> +			if (pp->num_vectors > MAX_MSI_IRQS ||
> +			    pp->num_vectors == 0) {
> +				dev_err(dev,
> +					"Invalid number of vectors\n");
>  				goto error;
>  			}
> +		}
>  
> -			for (i = 0; i < MAX_MSI_IRQS; i++)
> -				irq_create_mapping(pp->irq_domain, i);
> +		if (!pp->ops->msi_host_init) {
> +			ret = dw_pcie_allocate_domains(pp);
> +			if (ret)
> +				goto error;
> +
> +			if (pp->msi_irq)
> +				irq_set_chained_handler_and_data(pp->msi_irq,
> +							    dw_chained_msi_isr,
> +							    pp);
>  		} else {
>  			ret = pp->ops->msi_host_init(pp, &dw_pcie_msi_chip);
>  			if (ret < 0)
> @@ -424,10 +664,6 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  	bridge->ops = &dw_pcie_ops;
>  	bridge->map_irq = of_irq_parse_and_map_pci;
>  	bridge->swizzle_irq = pci_common_swizzle;
> -	if (IS_ENABLED(CONFIG_PCI_MSI)) {
> -		bridge->msi = &dw_pcie_msi_chip;
> -		dw_pcie_msi_chip.dev = dev;
> -	}
>  
>  	ret = pci_scan_root_bus_bridge(bridge);
>  	if (ret)
> @@ -596,11 +832,15 @@ static u8 dw_pcie_iatu_unroll_enabled(struct dw_pcie *pci)
>  
>  void dw_pcie_setup_rc(struct pcie_port *pp)
>  {
> -	u32 val;
> +	u32 val, ctrl;
>  	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
>  
>  	dw_pcie_setup(pci);
>  
> +	/* Initialize IRQ Status array */
> +	for (ctrl = 0; ctrl < MAX_MSI_CTRLS; ctrl++)
> +		dw_pcie_rd_own_conf(pp, PCIE_MSI_INTR0_ENABLE + (ctrl * 12), 4,
> +				    &pp->irq_status[ctrl]);
>  	/* setup RC BARs */
>  	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_0, 0x00000004);
>  	dw_pcie_writel_dbi(pci, PCI_BASE_ADDRESS_1, 0x00000000);
> diff --git a/drivers/pci/dwc/pcie-designware.h b/drivers/pci/dwc/pcie-designware.h
> index 8190465..b603e88 100644
> --- a/drivers/pci/dwc/pcie-designware.h
> +++ b/drivers/pci/dwc/pcie-designware.h
> @@ -117,6 +117,7 @@
>   */
>  #define MAX_MSI_IRQS			32
>  #define MAX_MSI_CTRLS			(MAX_MSI_IRQS / 32)
> +#define MSI_DEF_NUM_VECTORS		32
>  
>  /* Maximum number of inbound/outbound iATUs */
>  #define MAX_IATU_IN			256
> @@ -152,7 +153,9 @@ struct dw_pcie_host_ops {
>  	phys_addr_t (*get_msi_addr)(struct pcie_port *pp);
>  	u32 (*get_msi_data)(struct pcie_port *pp, int pos);
>  	void (*scan_bus)(struct pcie_port *pp);
> +	void (*set_num_vectors)(struct pcie_port *pp);
>  	int (*msi_host_init)(struct pcie_port *pp, struct msi_controller *chip);
> +	void (*msi_irq_ack)(int irq, struct pcie_port *pp);
>  };
>  
>  struct pcie_port {
> @@ -177,7 +180,11 @@ struct pcie_port {
>  	const struct dw_pcie_host_ops *ops;
>  	int			msi_irq;
>  	struct irq_domain	*irq_domain;
> +	struct irq_domain	*msi_domain;
>  	dma_addr_t		msi_data;
> +	u32			num_vectors;
> +	u32			irq_status[MAX_MSI_CTRLS];
> +	spinlock_t		lock;
>  	DECLARE_BITMAP(msi_irq_in_use, MAX_MSI_IRQS);
>  };
>  
> @@ -319,8 +326,10 @@ static inline void dw_pcie_dbi_ro_wr_dis(struct dw_pcie *pci)
>  #ifdef CONFIG_PCIE_DW_HOST
>  irqreturn_t dw_handle_msi_irq(struct pcie_port *pp);
>  void dw_pcie_msi_init(struct pcie_port *pp);
> +void dw_pcie_free_msi(struct pcie_port *pp);
>  void dw_pcie_setup_rc(struct pcie_port *pp);
>  int dw_pcie_host_init(struct pcie_port *pp);
> +int dw_pcie_allocate_domains(struct pcie_port *pp);
>  #else
>  static inline irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
>  {
> @@ -331,6 +340,10 @@ static inline void dw_pcie_msi_init(struct pcie_port *pp)
>  {
>  }
>  
> +static inline void dw_pcie_free_msi(struct pcie_port *pp)
> +{
> +}
> +
>  static inline void dw_pcie_setup_rc(struct pcie_port *pp)
>  {
>  }
> @@ -339,6 +352,11 @@ static inline int dw_pcie_host_init(struct pcie_port *pp)
>  {
>  	return 0;
>  }
> +
> +static inline int dw_pcie_allocate_domains(struct pcie_port *pp)
> +{
> +	return 0;
> +}
>  #endif
>  
>  #ifdef CONFIG_PCIE_DW_EP
> 

Thanks,

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