i2c: bcm-iproc: Fix bcm_iproc_i2c_isr deadlock issue

iproc_i2c_rd_reg() and iproc_i2c_wr_reg() are called from both
interrupt context (e.g. bcm_iproc_i2c_isr) and process context
(e.g. bcm_iproc_i2c_suspend). Therefore, interrupts should be
disabled to avoid potential deadlock. To prevent this scenario,
use spin_lock_irqsave().

Fixes: 9a1038728037 ("i2c: iproc: add NIC I2C support")
Signed-off-by: Chengfeng Ye <[e-mail]>
Acked-by: Ray Jui <[e-mail]>
Reviewed-by: Andi Shyti <[e-mail]>
Signed-off-by: Wolfram Sang <[e-mail]>

drivers/i2c/busses/i2c-bcm-iproc.c

···
 				   u32 offset)
 {
 	u32 val;
+	unsigned long flags;
 
 	if (iproc_i2c->idm_base) {
-		spin_lock(&iproc_i2c->idm_lock);
+		spin_lock_irqsave(&iproc_i2c->idm_lock, flags);
 		writel(iproc_i2c->ape_addr_mask,
 		       iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET);
 		val = readl(iproc_i2c->base + offset);
-		spin_unlock(&iproc_i2c->idm_lock);
+		spin_unlock_irqrestore(&iproc_i2c->idm_lock, flags);
 	} else {
 		val = readl(iproc_i2c->base + offset);
 	}
···
 static inline void iproc_i2c_wr_reg(struct bcm_iproc_i2c_dev *iproc_i2c,
 				    u32 offset, u32 val)
 {
+	unsigned long flags;
+
 	if (iproc_i2c->idm_base) {
-		spin_lock(&iproc_i2c->idm_lock);
+		spin_lock_irqsave(&iproc_i2c->idm_lock, flags);
 		writel(iproc_i2c->ape_addr_mask,
 		       iproc_i2c->idm_base + IDM_CTRL_DIRECT_OFFSET);
 		writel(val, iproc_i2c->base + offset);
-		spin_unlock(&iproc_i2c->idm_lock);
+		spin_unlock_irqrestore(&iproc_i2c->idm_lock, flags);
 	} else {
 		writel(val, iproc_i2c->base + offset);
 	}