gpio: ml-ioh: use raw_spinlock_t for the register lock

commit 600411e upstream.

ioh_irq_type() is registered as the irq_chip .irq_set_type callback and
takes chip->spinlock with spin_lock_irqsave().  This callback is reached
from __setup_irq() -> __irq_set_trigger() -> chip->irq_set_type() while
the caller holds desc->lock, a raw_spinlock_t, with hardirqs disabled.
That context is not sleepable, but on PREEMPT_RT a regular spinlock_t is
an rtmutex-backed sleeping lock, so acquiring it there is invalid.
ioh_irq_enable() and ioh_irq_disable() take the same lock from the
.irq_enable/.irq_disable callbacks, which are likewise invoked with
desc->lock held.

Convert the register lock to raw_spinlock_t.  The same lock also
serializes the GPIO direction/value callbacks and the suspend/resume
register save/restore, and those critical sections only perform short
sequences of MMIO register accesses (ioread32()/iowrite32()); the
.irq_set_type callback additionally emits a dev_warn() on an unsupported
type.  None of these are sleepable operations, so keeping this register
lock non-sleeping is appropriate for the irqchip callbacks and does not
change the GPIO-side locking contract.

This is the same fix as commit a02b895 ("gpio: pch: use
raw_spinlock_t for the register lock"); this driver shares the same
structure as gpio-pch.

Fixes: 54be566 ("gpio-ml-ioh: Support interrupt function")
Cc: stable@vger.kernel.org
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://patch.msgid.link/20260731032747.2987292-1-junjie.cao@intel.com
Signed-off-by: Junjie Cao <junjie.cao@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Junjie650

drivers/gpio/gpio-ml-ioh.c

@@ -84,7 +84,7 @@ struct ioh_gpio {
 	u32 gpio_use_sel;
 	int ch;
 	int irq_base;
-	spinlock_t spinlock;
+	raw_spinlock_t spinlock;
 };
 
 static const int num_ports[] = {6, 12, 16, 16, 15, 16, 16, 12};
@@ -95,15 +95,15 @@ static void ioh_gpio_set(struct gpio_chip *gpio, unsigned nr, int val)
 	struct ioh_gpio *chip =	gpiochip_get_data(gpio);
 	unsigned long flags;
 
-	spin_lock_irqsave(&chip->spinlock, flags);
+	raw_spin_lock_irqsave(&chip->spinlock, flags);
 	reg_val = ioread32(&chip->reg->regs[chip->ch].po);
 	if (val)
 		reg_val |= BIT(nr);
 	else
 		reg_val &= ~BIT(nr);
 
 	iowrite32(reg_val, &chip->reg->regs[chip->ch].po);
-	spin_unlock_irqrestore(&chip->spinlock, flags);
+	raw_spin_unlock_irqrestore(&chip->spinlock, flags);
 }
 
 static int ioh_gpio_get(struct gpio_chip *gpio, unsigned nr)
@@ -121,7 +121,7 @@ static int ioh_gpio_direction_output(struct gpio_chip *gpio, unsigned nr,
 	u32 reg_val;
 	unsigned long flags;
 
-	spin_lock_irqsave(&chip->spinlock, flags);
+	raw_spin_lock_irqsave(&chip->spinlock, flags);
 	pm = ioread32(&chip->reg->regs[chip->ch].pm);
 	pm &= BIT(num_ports[chip->ch]) - 1;
 	pm |= BIT(nr);
@@ -134,7 +134,7 @@ static int ioh_gpio_direction_output(struct gpio_chip *gpio, unsigned nr,
 		reg_val &= ~BIT(nr);
 	iowrite32(reg_val, &chip->reg->regs[chip->ch].po);
 
-	spin_unlock_irqrestore(&chip->spinlock, flags);
+	raw_spin_unlock_irqrestore(&chip->spinlock, flags);
 
 	return 0;
 }
@@ -145,12 +145,12 @@ static int ioh_gpio_direction_input(struct gpio_chip *gpio, unsigned nr)
 	u32 pm;
 	unsigned long flags;
 
-	spin_lock_irqsave(&chip->spinlock, flags);
+	raw_spin_lock_irqsave(&chip->spinlock, flags);
 	pm = ioread32(&chip->reg->regs[chip->ch].pm);
 	pm &= BIT(num_ports[chip->ch]) - 1;
 	pm &= ~BIT(nr);
 	iowrite32(pm, &chip->reg->regs[chip->ch].pm);
-	spin_unlock_irqrestore(&chip->spinlock, flags);
+	raw_spin_unlock_irqrestore(&chip->spinlock, flags);
 
 	return 0;
 }
@@ -254,7 +254,7 @@ static int ioh_irq_type(struct irq_data *d, unsigned int type)
 	dev_dbg(chip->dev, "%s:irq=%d type=%d ch=%d pos=%d type=%d\n",
 		__func__, irq, type, ch, im_pos, type);
 
-	spin_lock_irqsave(&chip->spinlock, flags);
+	raw_spin_lock_irqsave(&chip->spinlock, flags);
 
 	switch (type) {
 	case IRQ_TYPE_EDGE_RISING:
@@ -294,7 +294,7 @@ static int ioh_irq_type(struct irq_data *d, unsigned int type)
 	ien = ioread32(&chip->reg->regs[chip->ch].ien);
 	iowrite32(ien | BIT(ch), &chip->reg->regs[chip->ch].ien);
 end:
-	spin_unlock_irqrestore(&chip->spinlock, flags);
+	raw_spin_unlock_irqrestore(&chip->spinlock, flags);
 
 	return 0;
 }
@@ -324,11 +324,11 @@ static void ioh_irq_disable(struct irq_data *d)
 	unsigned long flags;
 	u32 ien;
 
-	spin_lock_irqsave(&chip->spinlock, flags);
+	raw_spin_lock_irqsave(&chip->spinlock, flags);
 	ien = ioread32(&chip->reg->regs[chip->ch].ien);
 	ien &= ~BIT(d->irq - chip->irq_base);
 	iowrite32(ien, &chip->reg->regs[chip->ch].ien);
-	spin_unlock_irqrestore(&chip->spinlock, flags);
+	raw_spin_unlock_irqrestore(&chip->spinlock, flags);
 }
 
 static void ioh_irq_enable(struct irq_data *d)
@@ -338,11 +338,11 @@ static void ioh_irq_enable(struct irq_data *d)
 	unsigned long flags;
 	u32 ien;
 
-	spin_lock_irqsave(&chip->spinlock, flags);
+	raw_spin_lock_irqsave(&chip->spinlock, flags);
 	ien = ioread32(&chip->reg->regs[chip->ch].ien);
 	ien |= BIT(d->irq - chip->irq_base);
 	iowrite32(ien, &chip->reg->regs[chip->ch].ien);
-	spin_unlock_irqrestore(&chip->spinlock, flags);
+	raw_spin_unlock_irqrestore(&chip->spinlock, flags);
 }
 
 static irqreturn_t ioh_gpio_handler(int irq, void *dev_id)
@@ -438,7 +438,7 @@ static int ioh_gpio_probe(struct pci_dev *pdev,
 		chip->base = base;
 		chip->reg = chip->base;
 		chip->ch = i;
-		spin_lock_init(&chip->spinlock);
+		raw_spin_lock_init(&chip->spinlock);
 		ioh_gpio_setup(chip, num_ports[i]);
 		ret = devm_gpiochip_add_data(dev, &chip->gpio, chip);
 		if (ret) {
@@ -482,9 +482,9 @@ static int __maybe_unused ioh_gpio_suspend(struct device *dev)
 	struct ioh_gpio *chip = dev_get_drvdata(dev);
 	unsigned long flags;
 
-	spin_lock_irqsave(&chip->spinlock, flags);
+	raw_spin_lock_irqsave(&chip->spinlock, flags);
 	ioh_gpio_save_reg_conf(chip);
-	spin_unlock_irqrestore(&chip->spinlock, flags);
+	raw_spin_unlock_irqrestore(&chip->spinlock, flags);
 
 	return 0;
 }
@@ -494,11 +494,11 @@ static int __maybe_unused ioh_gpio_resume(struct device *dev)
 	struct ioh_gpio *chip = dev_get_drvdata(dev);
 	unsigned long flags;
 
-	spin_lock_irqsave(&chip->spinlock, flags);
+	raw_spin_lock_irqsave(&chip->spinlock, flags);
 	iowrite32(0x01, &chip->reg->srst);
 	iowrite32(0x00, &chip->reg->srst);
 	ioh_gpio_restore_reg_conf(chip);
-	spin_unlock_irqrestore(&chip->spinlock, flags);
+	raw_spin_unlock_irqrestore(&chip->spinlock, flags);
 
 	return 0;
 }