Re: [PATCH RFC v2 02/18] irq/dev-msi: Add support for a new DEV_MSI irq domain

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Hi Jason,

On 7/21/2020 9:13 AM, Jason Gunthorpe wrote:
On Tue, Jul 21, 2020 at 09:02:28AM -0700, Dave Jiang wrote:
From: Megha Dey <megha.dey@xxxxxxxxx>

Add support for the creation of a new DEV_MSI irq domain. It creates a
new irq chip associated with the DEV_MSI domain and adds the necessary
domain operations to it.

Add a new config option DEV_MSI which must be enabled by any
driver that wants to support device-specific message-signaled-interrupts
outside of PCI-MSI(-X).

Lastly, add device specific mask/unmask callbacks in addition to a write
function to the platform_msi_ops.

Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Signed-off-by: Megha Dey <megha.dey@xxxxxxxxx>
Signed-off-by: Dave Jiang <dave.jiang@xxxxxxxxx>
  arch/x86/include/asm/hw_irq.h |    5 ++
  drivers/base/Kconfig          |    7 +++
  drivers/base/Makefile         |    1
  drivers/base/dev-msi.c        |   95 +++++++++++++++++++++++++++++++++++++++++
  drivers/base/platform-msi.c   |   45 +++++++++++++------
  drivers/base/platform-msi.h   |   23 ++++++++++
  include/linux/msi.h           |    8 +++
  7 files changed, 168 insertions(+), 16 deletions(-)
  create mode 100644 drivers/base/dev-msi.c
  create mode 100644 drivers/base/platform-msi.h

diff --git a/arch/x86/include/asm/hw_irq.h b/arch/x86/include/asm/hw_irq.h
index 74c12437401e..8ecd7570589d 100644
+++ b/arch/x86/include/asm/hw_irq.h
@@ -61,6 +61,11 @@ struct irq_alloc_info {
  			irq_hw_number_t	msi_hwirq;
  		};
  #endif
+#ifdef CONFIG_DEV_MSI
+		struct {
+			irq_hw_number_t hwirq;
+		};
+#endif

Why is this in this patch? I didn't see an obvious place where it is
used?

Since I have introduced the DEV-MSI domain and related ops, this is required in the dev_msi_set_hwirq and dev_msi_set_desc in this patch.

+static void __platform_msi_desc_mask_unmask_irq(struct msi_desc *desc, u32 mask)
+{
+	const struct platform_msi_ops *ops;
+
+	ops = desc->platform.msi_priv_data->ops;
+	if (!ops)
+		return;
+
+	if (mask) {
+		if (ops->irq_mask)
+			ops->irq_mask(desc);
+	} else {
+		if (ops->irq_unmask)
+			ops->irq_unmask(desc);
+	}
+}
+
+void platform_msi_mask_irq(struct irq_data *data)
+{
+	__platform_msi_desc_mask_unmask_irq(irq_data_get_msi_desc(data), 1);
+}
+
+void platform_msi_unmask_irq(struct irq_data *data)
+{
+	__platform_msi_desc_mask_unmask_irq(irq_data_get_msi_desc(data), 0);
+}

This is a bit convoluted, just call the op directly:

void platform_msi_unmask_irq(struct irq_data *data)
{
	const struct platform_msi_ops *ops = desc->platform.msi_priv_data->ops;

	if (ops->irq_unmask)
		ops->irq_unmask(desc);
}


Sure, I will update this.

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 7f6a8eb51aca..1da97f905720 100644
+++ b/include/linux/msi.h
@@ -323,9 +323,13 @@ enum {
/*
   * platform_msi_ops - Callbacks for platform MSI ops
+ * @irq_mask:   mask an interrupt source
+ * @irq_unmask: unmask an interrupt source
   * @write_msg:	write message content
   */
  struct platform_msi_ops {
+	unsigned int            (*irq_mask)(struct msi_desc *desc);
+	unsigned int            (*irq_unmask)(struct msi_desc *desc);

Why do these functions return things if the only call site throws it
away?

Hmmm, fair enough, I will change it to void.


Jason




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