[PATCH] serial: sc16is7xx: declare MCR and IER as volatile registers

[Hugo Villeneuve]

From: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>

MCR register has the same address as XON1 register.
IER register has the same address as DLH register.

Which register is accessed depends on bits configuration in some
other registers.

To prevent potential access errors, declare MCR and IER as volatile
registers.

Fixes: dfeae619d781 ("serial: sc16is7xx")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Hugo Villeneuve <hvilleneuve@xxxxxxxxxxxx>
---
 drivers/tty/serial/sc16is7xx.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 296079c16fdb9..d6b3b67d17d55 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -501,7 +501,9 @@ static bool sc16is7xx_regmap_volatile(struct device *dev, unsigned int reg)
 {
 	switch (reg) {
 	case SC16IS7XX_RHR_REG: /* Shared address space with THR & DLL */
+	case SC16IS7XX_IER_REG: /* Shared address space with DLH */
 	case SC16IS7XX_IIR_REG: /* Shared address space with FCR & EFR */
+	case SC16IS7XX_MCR_REG: /* Shared address space with XON1 */
 	case SC16IS7XX_LSR_REG: /* Shared address space with XON2 */
 	case SC16IS7XX_MSR_REG: /* Shared address space with TCR & XOFF1 */
 	case SC16IS7XX_SPR_REG: /* Shared address space with TLR & XOFF2 */

base-commit: 36844ea19656fb41278799ef3d5cd52120d89149
-- 
2.47.3