Re: [RFC v2 1/8] pci: adding new irq api to pci-designware

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

On Mon, May 15 2017 at 06:03:41 PM, Joao Pinto <Joao.Pinto@synopsys.com> wrote:
> This patch adds the new interrupt api to pcie-designware, keeping the old
> one. Although the old API is still available, pcie-designware initiates with
> the new one.
>
> Signed-off-by: Joao Pinto <jpinto@synopsys.com>
> ---
> changes v1->v2:
> - Now there's no config to toggle between the 2 APIs, so pcie-designware
> initiaties wih the new one by default
> - Using lower_32_bits / upper_32_bits
> - Instead of mutex, now using spinlocks
> - Instead of always reading PCIE_MSI_INTR0_ENABLE, now we use an internal
> variable
> - dw_pcie_irq_domain_alloc() was updated to enable Multi-MSI
> - using irq_domain_create_linear() instead of irq_domain_add_linear()
>
>  drivers/pci/dwc/pcie-designware-host.c | 272 +++++++++++++++++++++++++++++----
>  drivers/pci/dwc/pcie-designware.h      |  15 ++
>  2 files changed, 258 insertions(+), 29 deletions(-)
>
> diff --git a/drivers/pci/dwc/pcie-designware-host.c b/drivers/pci/dwc/pcie-designware-host.c
> index 28ed32b..78ce002 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 +54,28 @@ static struct irq_chip dw_msi_irq_chip = {
>  	.irq_unmask = pci_msi_unmask_irq,
>  };
>  
> +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_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),

How is Multi-MSI supported if you don't pass the MSI_FLAG_MULTI_PCI_MSI
flag?

> +	.chip	= &dw_pcie_msi_irq_chip,
> +};
> +
>  /* MSI int handler */
>  irqreturn_t dw_handle_msi_irq(struct pcie_port *pp)
>  {
> @@ -81,6 +104,191 @@ 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;
> +	struct dw_pcie *pci;
> +
> +	chained_irq_enter(chip, desc);
> +	pci = irq_desc_get_handler_data(desc);
> +	pp = &pci->pp;
> +
> +	dw_handle_msi_irq(pp);
> +
> +	chained_irq_exit(chip, desc);
> +}
> +
> +static void dw_pci_setup_msi_msg(struct irq_data *data, struct msi_msg *msg)
> +{
> +	struct dw_pcie *pci = irq_data_get_irq_chip_data(data);
> +	struct pcie_port *pp = &pci->pp;
> +	u64 msi_target;
> +
> +	if (pp->ops->get_msi_addr)
> +		msi_target = pp->ops->get_msi_addr(pp);
> +	else
> +		msi_target = virt_to_phys((void *)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);

I've already asked about the reason for this indirection, and I'd
appreciate an answer.

> +	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 dw_pcie *pci = irq_data_get_irq_chip_data(data);
> +	struct pcie_port *pp = &pci->pp;
> +	unsigned int res, bit, ctrl;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pp->lock, flags);
> +
> +	if (pp->ops->msi_clear_irq)
> +		pp->ops->msi_clear_irq(pp, data->hwirq);

Same thing. If you have to have that kind of indirection, then this is a
different irqchip altogether. Also, see below for the coding-style.

> +	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 dw_pcie *pci = irq_data_get_irq_chip_data(data);
> +	struct pcie_port *pp = &pci->pp;
> +	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 {

Coding-style:

        if (...) {
        	...
        } 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 struct irq_chip dw_pci_msi_bottom_irq_chip = {
> +	.name			= "DWPCI-MSI",
> +	.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 dw_pcie *pci = domain->host_data;
> +	struct pcie_port *pp = &pci->pp;
> +	unsigned long flags;
> +	unsigned long bit;
> +	u32 i;
> +
> +	spin_lock_irqsave(&pp->lock, flags);
> +
> +	bit = bitmap_find_next_zero_area(pp->msi_irq_in_use, pp->num_vectors, 0,
> +					 nr_irqs, 0);
> +
> +	if (bit >= pp->num_vectors) {
> +		spin_unlock_irqrestore(&pp->lock, flags);
> +		return -ENOSPC;
> +	}
> +
> +	bitmap_set(pp->msi_irq_in_use, bit, nr_irqs);
> +
> +	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,
> +				    domain->host_data, handle_simple_irq,
> +				    NULL, NULL);
> +
> +	return 0;

How does this work when you're using the indirection I've moaned about
earlier? How can you guarantee that there are similar number of
available vectors?

> +}
> +
> +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 dw_pcie *pci = irq_data_get_irq_chip_data(data);
> +	struct pcie_port *pp = &pci->pp;
> +	unsigned long flags;
> +
> +	spin_lock_irqsave(&pp->lock, flags);
> +	bitmap_clear(pp->msi_irq_in_use, data->hwirq, 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 dw_pcie *pci)
> +{
> +	struct pcie_port *pp = &pci->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, pci);
> +	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)
>  {
>  	u64 msi_target;
> @@ -97,13 +305,14 @@ void dw_pcie_msi_init(struct pcie_port *pp)
>  
>  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,
> @@ -125,13 +334,14 @@ 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)
> @@ -279,11 +489,14 @@ 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 resource *cfg_res;
>  	int i, ret;
> +
>  	LIST_HEAD(res);
> -	struct resource_entry *win, *tmp;
> +
> +	spin_lock_init(&pci->pp.lock);
>  
>  	cfg_res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "config");
>  	if (cfg_res) {
> @@ -378,17 +591,18 @@ int dw_pcie_host_init(struct pcie_port *pp)
>  
>  	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;
> +			ret = of_property_read_u32(np, "num-vectors",
> +						   &pp->num_vectors);
> +			if (ret)
> +				pp->num_vectors = 1;

1? As in "one bit only"? Is that a valid configuration? Also, all of
this code seems to assume a maximum number of 32 MSIs. Is that a real
limitation? Because if that's the case, you can drop all the stuff about
ctrl and the '* 12' offset all over the code.

Thanks,

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