i3c: mipi-i3c-hci: Fix handling of shared IRQs during early initialization

Shared interrupts may fire unexpectedly, including during periods when the
controller is not yet fully initialized. Commit b9a15012a1452
("i3c: mipi-i3c-hci: Add optional Runtime PM support") addressed this issue
for the runtime-suspended state, but the same problem can also occur before
the bus is enabled for the first time.

Ensure the IRQ handler ignores interrupts until initialization is complete
by making consistent use of the existing irq_inactive flag.  The flag is
now set to false immediately before enabling the bus.

To guarantee correct ordering with respect to the IRQ handler, protect
all transitions of irq_inactive with the same spinlock used inside the
handler.

Fixes: b8460480f62e1 ("i3c: mipi-i3c-hci: Allow for Multi-Bus Instances")
Cc: stable@vger.kernel.org
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260306072451.11131-14-adrian.hunter@intel.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/i3c/master/mipi-i3c-hci/core.c b/drivers/i3c/master/mipi-i3c-hci/core.c
index b98952d12d7ce69df1eabba09c302226bc0f406b..d5e91af7d56913bb16255ca7b17f642cef11daef 100644 (file)
--- a/drivers/i3c/master/mipi-i3c-hci/core.c
+++ b/drivers/i3c/master/mipi-i3c-hci/core.c
@@ -152,6 +152,9 @@ static int i3c_hci_bus_init(struct i3c_master_controller *m)
        if (hci->quirks & HCI_QUIRK_RESP_BUF_THLD)
                amd_set_resp_buf_thld(hci);
 
+       scoped_guard(spinlock_irqsave, &hci->lock)
+               hci->irq_inactive = false;
+
        /* Enable bus with Hot-Join disabled */
        reg_set(HC_CONTROL, HC_CONTROL_BUS_ENABLE | HC_CONTROL_HOT_JOIN_CTRL);
        dev_dbg(&hci->master.dev, "HC_CONTROL = %#x", reg_read(HC_CONTROL));
@@ -184,8 +187,9 @@ void i3c_hci_sync_irq_inactive(struct i3c_hci *hci)
        int irq = platform_get_irq(pdev, 0);
 
        reg_write(INTR_SIGNAL_ENABLE, 0x0);
-       hci->irq_inactive = true;
        synchronize_irq(irq);
+       scoped_guard(spinlock_irqsave, &hci->lock)
+               hci->irq_inactive = true;
 }
 
 static void i3c_hci_bus_cleanup(struct i3c_master_controller *m)
@@ -781,10 +785,11 @@ static int i3c_hci_runtime_resume(struct device *dev)
 
        mipi_i3c_hci_dat_v1.restore(hci);
 
-       hci->irq_inactive = false;
-
        hci->io->resume(hci);
 
+       scoped_guard(spinlock_irqsave, &hci->lock)
+               hci->irq_inactive = false;
+
        /* Enable bus with Hot-Join disabled */
        reg_set(HC_CONTROL, HC_CONTROL_BUS_ENABLE | HC_CONTROL_HOT_JOIN_CTRL);
 
@@ -975,6 +980,8 @@ static int i3c_hci_probe(struct platform_device *pdev)
        if (ret)
                return ret;
 
+       hci->irq_inactive = true;
+
        irq = platform_get_irq(pdev, 0);
        ret = devm_request_irq(&pdev->dev, irq, i3c_hci_irq_handler,
                               IRQF_SHARED, NULL, hci);