PCI: dwc: Code cleanup

Code cleanup with no functional changes. These changes were originally
made by Thomas Gleixner (see Link tag below) in a patch that was never
submitted as is. Other parts of that patch were eventually submitted as
commit 8e71711 ("PCI: dwc: Switch to msi_create_parent_irq_domain()")
and the remaining parts are the code cleanup changes:

    - Use guard()/scoped_guard() instead of open-coded lock/unlock.
    - Return void in a few functions whose return value is never used.
    - Simplify dw_handle_msi_irq() by using for_each_set_bit().

One notable deviation from the original patch is that it reverts back to a
simple 1 by 1 iteration over the controllers inside dw_handle_msi_irq.  The
reason is that with the original changes, the IRQ offset was calculated
incorrectly.

This prepares the ground for enabling MSI affinity support, which was
originally part of that same series that Thomas Gleixner prepared.

Originally-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Radu Rendec <rrendec@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/linux-pci/878qpg4o4t.ffs@tglx/
Link: https://patch.msgid.link/20251128212055.1409093-3-rrendec@redhat.com
(cherry picked from commit f187509)

Author: rrendec

drivers/pci/controller/dwc/pcie-designware-host.c

@@ -48,35 +48,25 @@ static const struct msi_parent_ops dw_pcie_msi_parent_ops = {
 };
 
 /* MSI int handler */
-irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp)
+void dw_handle_msi_irq(struct dw_pcie_rp *pp)
 {
-	int i, pos;
-	unsigned long val;
-	u32 status, num_ctrls;
-	irqreturn_t ret = IRQ_NONE;
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
+	unsigned int i, num_ctrls;
 
 	num_ctrls = pp->num_vectors / MAX_MSI_IRQS_PER_CTRL;
 
 	for (i = 0; i < num_ctrls; i++) {
-		status = dw_pcie_readl_dbi(pci, PCIE_MSI_INTR0_STATUS +
-					   (i * MSI_REG_CTRL_BLOCK_SIZE));
+		unsigned int reg_off = i * MSI_REG_CTRL_BLOCK_SIZE;
+		unsigned int irq_off = i * MAX_MSI_IRQS_PER_CTRL;
+		unsigned long status, pos;
+
+		status = dw_pcie_readl_dbi(pci, PCIE_MSI_INTR0_STATUS + reg_off);
 		if (!status)
 			continue;
 
-		ret = IRQ_HANDLED;
-		val = status;
-		pos = 0;
-		while ((pos = find_next_bit(&val, MAX_MSI_IRQS_PER_CTRL,
-					    pos)) != MAX_MSI_IRQS_PER_CTRL) {
-			generic_handle_domain_irq(pp->irq_domain,
-						  (i * MAX_MSI_IRQS_PER_CTRL) +
-						  pos);
-			pos++;
-		}
+		for_each_set_bit(pos, &status, MAX_MSI_IRQS_PER_CTRL)
+			generic_handle_domain_irq(pp->irq_domain, irq_off + pos);
 	}
-
-	return ret;
 }
 
 /* Chained MSI interrupt service routine */
@@ -97,13 +87,10 @@ static void dw_pci_setup_msi_msg(struct irq_data *d, struct msi_msg *msg)
 {
 	struct dw_pcie_rp *pp = irq_data_get_irq_chip_data(d);
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
-	u64 msi_target;
-
-	msi_target = (u64)pp->msi_data;
+	u64 msi_target = (u64)pp->msi_data;
 
 	msg->address_lo = lower_32_bits(msi_target);
 	msg->address_hi = upper_32_bits(msi_target);
-
 	msg->data = d->hwirq;
 
 	dev_dbg(pci->dev, "msi#%d address_hi %#x address_lo %#x\n",
@@ -115,37 +102,29 @@ static void dw_pci_bottom_mask(struct irq_data *d)
 	struct dw_pcie_rp *pp = irq_data_get_irq_chip_data(d);
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 	unsigned int res, bit, ctrl;
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&pp->lock, flags);
 
+	guard(raw_spinlock)(&pp->lock);
 	ctrl = d->hwirq / MAX_MSI_IRQS_PER_CTRL;
 	res = ctrl * MSI_REG_CTRL_BLOCK_SIZE;
 	bit = d->hwirq % MAX_MSI_IRQS_PER_CTRL;
 
 	pp->irq_mask[ctrl] |= BIT(bit);
 	dw_pcie_writel_dbi(pci, PCIE_MSI_INTR0_MASK + res, pp->irq_mask[ctrl]);
-
-	raw_spin_unlock_irqrestore(&pp->lock, flags);
 }
 
 static void dw_pci_bottom_unmask(struct irq_data *d)
 {
 	struct dw_pcie_rp *pp = irq_data_get_irq_chip_data(d);
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
 	unsigned int res, bit, ctrl;
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&pp->lock, flags);
 
+	guard(raw_spinlock)(&pp->lock);
 	ctrl = d->hwirq / MAX_MSI_IRQS_PER_CTRL;
 	res = ctrl * MSI_REG_CTRL_BLOCK_SIZE;
 	bit = d->hwirq % MAX_MSI_IRQS_PER_CTRL;
 
 	pp->irq_mask[ctrl] &= ~BIT(bit);
 	dw_pcie_writel_dbi(pci, PCIE_MSI_INTR0_MASK + res, pp->irq_mask[ctrl]);
-
-	raw_spin_unlock_irqrestore(&pp->lock, flags);
 }
 
 static void dw_pci_bottom_ack(struct irq_data *d)
@@ -162,54 +141,42 @@ static void dw_pci_bottom_ack(struct irq_data *d)
 }
 
 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_mask = dw_pci_bottom_mask,
-	.irq_unmask = dw_pci_bottom_unmask,
+	.name			= "DWPCI-MSI",
+	.irq_ack		= dw_pci_bottom_ack,
+	.irq_compose_msi_msg	= dw_pci_setup_msi_msg,
+	.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)
+static int dw_pcie_irq_domain_alloc(struct irq_domain *domain, unsigned int virq,
+				    unsigned int nr_irqs, void *args)
 {
 	struct dw_pcie_rp *pp = domain->host_data;
-	unsigned long flags;
-	u32 i;
 	int bit;
 
-	raw_spin_lock_irqsave(&pp->lock, flags);
-
-	bit = bitmap_find_free_region(pp->msi_irq_in_use, pp->num_vectors,
-				      order_base_2(nr_irqs));
-
-	raw_spin_unlock_irqrestore(&pp->lock, flags);
+	scoped_guard (raw_spinlock_irq, &pp->lock) {
+		bit = bitmap_find_free_region(pp->msi_irq_in_use, pp->num_vectors,
+					      order_base_2(nr_irqs));
+	}
 
 	if (bit < 0)
 		return -ENOSPC;
 
-	for (i = 0; i < nr_irqs; i++)
-		irq_domain_set_info(domain, virq + i, bit + i,
-				    pp->msi_irq_chip,
-				    pp, handle_edge_irq,
-				    NULL, NULL);
-
+	for (unsigned int i = 0; i < nr_irqs; i++) {
+		irq_domain_set_info(domain, virq + i, bit + i, pp->msi_irq_chip,
+				    pp, handle_edge_irq, NULL, NULL);
+	}
 	return 0;
 }
 
-static void dw_pcie_irq_domain_free(struct irq_domain *domain,
-				    unsigned int virq, unsigned int nr_irqs)
+static void dw_pcie_irq_domain_free(struct irq_domain *domain, unsigned int virq,
+				    unsigned int nr_irqs)
 {
 	struct irq_data *d = irq_domain_get_irq_data(domain, virq);
 	struct dw_pcie_rp *pp = domain->host_data;
-	unsigned long flags;
-
-	raw_spin_lock_irqsave(&pp->lock, flags);
 
-	bitmap_release_region(pp->msi_irq_in_use, d->hwirq,
-			      order_base_2(nr_irqs));
-
-	raw_spin_unlock_irqrestore(&pp->lock, flags);
+	guard(raw_spinlock_irq)(&pp->lock);
+	bitmap_release_region(pp->msi_irq_in_use, d->hwirq, order_base_2(nr_irqs));
 }
 
 static const struct irq_domain_ops dw_pcie_msi_domain_ops = {
@@ -242,8 +209,7 @@ void dw_pcie_free_msi(struct dw_pcie_rp *pp)
 
 	for (ctrl = 0; ctrl < MAX_MSI_CTRLS; ctrl++) {
 		if (pp->msi_irq[ctrl] > 0)
-			irq_set_chained_handler_and_data(pp->msi_irq[ctrl],
-							 NULL, NULL);
+			irq_set_chained_handler_and_data(pp->msi_irq[ctrl], NULL, NULL);
 	}
 
 	irq_domain_remove(pp->irq_domain);

drivers/pci/controller/dwc/pcie-designware.h

@@ -816,7 +816,7 @@ const char *dw_pcie_ltssm_status_string(enum dw_pcie_ltssm ltssm);
 #ifdef CONFIG_PCIE_DW_HOST
 int dw_pcie_suspend_noirq(struct dw_pcie *pci);
 int dw_pcie_resume_noirq(struct dw_pcie *pci);
-irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp);
+void dw_handle_msi_irq(struct dw_pcie_rp *pp);
 void dw_pcie_msi_init(struct dw_pcie_rp *pp);
 int dw_pcie_msi_host_init(struct dw_pcie_rp *pp);
 void dw_pcie_free_msi(struct dw_pcie_rp *pp);
@@ -837,10 +837,7 @@ static inline int dw_pcie_resume_noirq(struct dw_pcie *pci)
 	return 0;
 }
 
-static inline irqreturn_t dw_handle_msi_irq(struct dw_pcie_rp *pp)
-{
-	return IRQ_NONE;
-}
+static inline void dw_handle_msi_irq(struct dw_pcie_rp *pp) { }
 
 static inline void dw_pcie_msi_init(struct dw_pcie_rp *pp)
 { }