linux-kernel - [RFC PATCH v2 07/21] serial: 8250_pnp: Add support for deferred probe

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Date:   Thu, 26 Oct 2023 01:53:30 +0530
From:   Sunil V L <sunilvl@...tanamicro.com>
To:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        linux-riscv@...ts.infradead.org, linux-acpi@...r.kernel.org,
        linux-pci@...r.kernel.org, linux-serial@...r.kernel.org
Cc:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        "Rafael J . Wysocki" <rafael@...nel.org>,
        Len Brown <lenb@...nel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Anup Patel <anup@...infault.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Jiri Slaby <jirislaby@...nel.org>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Andrew Jones <ajones@...tanamicro.com>,
        Atish Kumar Patra <atishp@...osinc.com>,
        Haibo Xu <haibo1.xu@...el.com>,
        Sunil V L <sunilvl@...tanamicro.com>
Subject: [RFC PATCH v2 07/21] serial: 8250_pnp: Add support for deferred probe

With pnp_irq() able to return error code, enhance the serial pnp driver
to support deferred probing. Return -EPROBE_DEFER when pnp_irq() returns
the same so that the driver probe is deferred.

Signed-off-by: Sunil V L <sunilvl@...tanamicro.com>
---
 drivers/tty/serial/8250/8250_pnp.c | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_pnp.c b/drivers/tty/serial/8250/8250_pnp.c
index 1974bbadc975..dcb3daf7c816 100644
--- a/drivers/tty/serial/8250/8250_pnp.c
+++ b/drivers/tty/serial/8250/8250_pnp.c
@@ -8,6 +8,7 @@
  *
  *  Ported to the Linux PnP Layer - (C) Adam Belay.
  */
+#include <linux/acpi.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/pnp.h>
@@ -443,8 +444,21 @@ serial_pnp_probe(struct pnp_dev *dev, const struct pnp_device_id *dev_id)
 	}
 
 	memset(&uart, 0, sizeof(uart));
-	if (pnp_irq_valid(dev, 0))
-		uart.port.irq = pnp_irq(dev, 0);
+	if (pnp_irq_valid(dev, 0)) {
+		ret = pnp_irq(dev, 0);
+		if (ret == -EPROBE_DEFER) {
+			struct resource r;
+
+			ret = acpi_irq_get(ACPI_HANDLE(&dev->dev), 0, &r);
+			if (!ret)
+				uart.port.irq = r.start;
+			else
+				return ret;
+		} else {
+			uart.port.irq = ret;
+		}
+	}
+
 	if ((flags & CIR_PORT) && pnp_port_valid(dev, 2)) {
 		uart.port.iobase = pnp_port_start(dev, 2);
 		uart.port.iotype = UPIO_PORT;
-- 
2.39.2