PCI/switchtec: Add check of event support

Not all events are supported by every gen/variant of the Switchtec
firmware. To solve this, since Gen4, a new bit in each event header
is introduced to indicate if an event is supported by the firmware.

Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Logan Gunthorpe <[e-mail]>
Signed-off-by: Kelvin Cao <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>

drivers/pci/switch/switchtec.c

···
 		return PTR_ERR(reg);
 
 	hdr = ioread32(reg);
+	if (hdr & SWITCHTEC_EVENT_NOT_SUPP)
+		return -EOPNOTSUPP;
+
 	for (i = 0; i < ARRAY_SIZE(ctl->data); i++)
 		ctl->data[i] = ioread32(&reg[i + 1]);
 
···
 		for (ctl.index = 0; ctl.index < nr_idxs; ctl.index++) {
 			ctl.flags = event_flags;
 			ret = event_ctl(stdev, &ctl);
-			if (ret < 0)
+			if (ret < 0 && ret != -EOPNOTSUPP)
 				return ret;
 		}
 	} else {
···
 
 	hdr_reg = event_regs[eid].map_reg(stdev, off, idx);
 	hdr = ioread32(hdr_reg);
+
+	if (hdr & SWITCHTEC_EVENT_NOT_SUPP)
+		return 0;
 
 	if (!(hdr & SWITCHTEC_EVENT_OCCURRED && hdr & SWITCHTEC_EVENT_EN_IRQ))
 		return 0;

include/linux/switchtec.h

···
 #define SWITCHTEC_EVENT_EN_CLI   BIT(2)
 #define SWITCHTEC_EVENT_EN_IRQ   BIT(3)
 #define SWITCHTEC_EVENT_FATAL    BIT(4)
+#define SWITCHTEC_EVENT_NOT_SUPP BIT(31)
 
 #define SWITCHTEC_DMA_MRPC_EN	BIT(0)