gpio: etraxfs: make use of raw_spinlock variants

The etraxfs gpio driver currently implements an irq_chip for handling
interrupts; due to how irq_chip handling is done, it's necessary for the
irq_chip methods to be invoked from hardirq context, even on a a
real-time kernel. Because the spinlock_t type becomes a "sleeping"
spinlock w/ RT kernels, it is not suitable to be used with irq_chips.

A quick audit of the operations under the lock reveal that they do only
minimal, bounded work, and are therefore safe to do under a raw spinlock.

Signed-off-by: Julia Cartwright <[e-mail]>
Signed-off-by: Linus Walleij <[e-mail]>

drivers/gpio/gpio-etraxfs.c

···
 struct etraxfs_gpio_info;
 
 struct etraxfs_gpio_block {
-	spinlock_t lock;
+	raw_spinlock_t lock;
 	u32 mask;
 	u32 cfg;
 	u32 pins;
···
 	struct etraxfs_gpio_block *block = chip->block;
 	unsigned int grpirq = etraxfs_gpio_to_group_irq(d->hwirq);
 
-	spin_lock(&block->lock);
+	raw_spin_lock(&block->lock);
 	block->mask &= ~BIT(grpirq);
 	writel(block->mask, block->regs + block->info->rw_intr_mask);
-	spin_unlock(&block->lock);
+	raw_spin_unlock(&block->lock);
 }
 
 static void etraxfs_gpio_irq_unmask(struct irq_data *d)
···
 	struct etraxfs_gpio_block *block = chip->block;
 	unsigned int grpirq = etraxfs_gpio_to_group_irq(d->hwirq);
 
-	spin_lock(&block->lock);
+	raw_spin_lock(&block->lock);
 	block->mask |= BIT(grpirq);
 	writel(block->mask, block->regs + block->info->rw_intr_mask);
-	spin_unlock(&block->lock);
+	raw_spin_unlock(&block->lock);
 }
 
 static int etraxfs_gpio_irq_set_type(struct irq_data *d, u32 type)
···
 		return -EINVAL;
 	}
 
-	spin_lock(&block->lock);
+	raw_spin_lock(&block->lock);
 	block->cfg &= ~(0x7 << (grpirq * 3));
 	block->cfg |= (cfg << (grpirq * 3));
 	writel(block->cfg, block->regs + block->info->rw_intr_cfg);
-	spin_unlock(&block->lock);
+	raw_spin_unlock(&block->lock);
 
 	return 0;
 }
···
 	unsigned int grpirq = etraxfs_gpio_to_group_irq(d->hwirq);
 	int ret = -EBUSY;
 
-	spin_lock(&block->lock);
+	raw_spin_lock(&block->lock);
 	if (block->group[grpirq])
 		goto out;
 
···
 	}
 
 out:
-	spin_unlock(&block->lock);
+	raw_spin_unlock(&block->lock);
 	return ret;
 }
 
···
 	struct etraxfs_gpio_block *block = chip->block;
 	unsigned int grpirq = etraxfs_gpio_to_group_irq(d->hwirq);
 
-	spin_lock(&block->lock);
+	raw_spin_lock(&block->lock);
 	block->group[grpirq] = 0;
 	gpiochip_unlock_as_irq(&chip->gc, d->hwirq);
-	spin_unlock(&block->lock);
+	raw_spin_unlock(&block->lock);
 }
 
 static struct irq_chip etraxfs_gpio_irq_chip = {
···
 	if (!block)
 		return -ENOMEM;
 
-	spin_lock_init(&block->lock);
+	raw_spin_lock_init(&block->lock);
 
 	block->regs = regs;
 	block->info = info;