irqchip/irq-mtk-sysirq: Replace spinlock with raw_spinlock

This driver may take a regular spinlock when a raw spinlock
(irq_desc->lock) is already taken which results in the following
lockdep splat:

=============================
[ BUG: Invalid wait context ]
5.7.0-rc7 #1 Not tainted
-----------------------------
swapper/0/0 is trying to lock:
ffffff800303b798 (&chip_data->lock){....}-{3:3}, at: mtk_sysirq_set_type+0x48/0xc0
other info that might help us debug this:
context-{5:5}
2 locks held by swapper/0/0:
#0: ffffff800302ee68 (&desc->request_mutex){....}-{4:4}, at: __setup_irq+0xc4/0x8a0
#1: ffffff800302ecf0 (&irq_desc_lock_class){....}-{2:2}, at: __setup_irq+0xe4/0x8a0
stack backtrace:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.7.0-rc7 #1
Hardware name: Pumpkin MT8516 (DT)
Call trace:
dump_backtrace+0x0/0x180
show_stack+0x14/0x20
dump_stack+0xd0/0x118
__lock_acquire+0x8c8/0x2270
lock_acquire+0xf8/0x470
_raw_spin_lock_irqsave+0x50/0x78
mtk_sysirq_set_type+0x48/0xc0
__irq_set_trigger+0x58/0x170
__setup_irq+0x420/0x8a0
request_threaded_irq+0xd8/0x190
timer_of_init+0x1e8/0x2c4
mtk_gpt_init+0x5c/0x1dc
timer_probe+0x74/0xf4
time_init+0x14/0x44
start_kernel+0x394/0x4f0

Replace the spinlock_t with raw_spinlock_t to avoid this warning.

Signed-off-by: Bartosz Golaszewski <[e-mail]>
Signed-off-by: Marc Zyngier <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]

drivers/irqchip/irq-mtk-sysirq.c

···
 #include <linux/spinlock.h>
 
 struct mtk_sysirq_chip_data {
-	spinlock_t lock;
+	raw_spinlock_t lock;
 	u32 nr_intpol_bases;
 	void __iomem **intpol_bases;
 	u32 *intpol_words;
···
 	reg_index = chip_data->which_word[hwirq];
 	offset = hwirq & 0x1f;
 
-	spin_lock_irqsave(&chip_data->lock, flags);
+	raw_spin_lock_irqsave(&chip_data->lock, flags);
 	value = readl_relaxed(base + reg_index * 4);
 	if (type == IRQ_TYPE_LEVEL_LOW || type == IRQ_TYPE_EDGE_FALLING) {
 		if (type == IRQ_TYPE_LEVEL_LOW)
···
 
 	data = data->parent_data;
 	ret = data->chip->irq_set_type(data, type);
-	spin_unlock_irqrestore(&chip_data->lock, flags);
+	raw_spin_unlock_irqrestore(&chip_data->lock, flags);
 	return ret;
 }
 
···
 		ret = -ENOMEM;
 		goto out_free_which_word;
 	}
-	spin_lock_init(&chip_data->lock);
+	raw_spin_lock_init(&chip_data->lock);
 
 	return 0;