scsi: ufs: avoid spurious UFS host controller interrupts

When control reaches to Linux UFS driver during UFS boot mode, UFS host
controller interrupt status/enable registers may have left over
settings.
In order to avoid any spurious interrupts due to these left overs,
it's important to clear these interrupt status/enable registers before
enabling UFS interrupt handling.

Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufshcd.c

@@ -5837,6 +5837,21 @@ int ufshcd_init(struct ufs_hba *hba, void __iomem *mmio_base, unsigned int irq)
 	init_waitqueue_head(&hba->dev_cmd.tag_wq);
 
 	ufshcd_init_clk_gating(hba);
+
+	/*
+	 * In order to avoid any spurious interrupt immediately after
+	 * registering UFS controller interrupt handler, clear any pending UFS
+	 * interrupt status and disable all the UFS interrupts.
+	 */
+	ufshcd_writel(hba, ufshcd_readl(hba, REG_INTERRUPT_STATUS),
+		      REG_INTERRUPT_STATUS);
+	ufshcd_writel(hba, 0, REG_INTERRUPT_ENABLE);
+	/*
+	 * Make sure that UFS interrupts are disabled and any pending interrupt
+	 * status is cleared before registering UFS interrupt handler.
+	 */
+	mb();
+
 	/* IRQ registration */
 	err = devm_request_irq(dev, irq, ufshcd_intr, IRQF_SHARED, UFSHCD, hba);
 	if (err) {