watchdog: s3c2410: Implement a way to invert mask reg value

On new Exynos chips (like Exynos850) the MASK_WDT_RESET_REQUEST register
is replaced with CLUSTERx_NONCPU_INT_EN, and its mask bit value meaning
was reversed: for new register the bit value "1" means "Interrupt
enabled", while for MASK_WDT_RESET_REQUEST register "1" means "Mask the
interrupt" (i.e. "Interrupt disabled").

Introduce "mask_reset_inv" boolean field in driver data structure; when
that field is "true", mask register handling function will invert the
value before setting it to the register.

This commit doesn't bring any functional change to existing devices, but
merely provides an infrastructure for upcoming chips support.
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20211107202943.8859-8-semen.protsenko@linaro.orgSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/s3c2410_wdt.c

@@ -92,6 +92,7 @@ MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to
  * timer reset functionality.
  * @mask_reset_reg: Offset in pmureg for the register that masks the watchdog
  * timer reset functionality.
+ * @mask_reset_inv: If set, mask_reset_reg value will have inverted meaning.
  * @mask_bit: Bit number for the watchdog timer in the disable register and the
  * mask reset register.
  * @rst_stat_reg: Offset in pmureg for the register that has the reset status.
@@ -103,6 +104,7 @@ MODULE_PARM_DESC(soft_noboot, "Watchdog action, set to 1 to ignore reboots, 0 to
 struct s3c2410_wdt_variant {
 	int disable_reg;
 	int mask_reset_reg;
+	bool mask_reset_inv;
 	int mask_bit;
 	int rst_stat_reg;
 	int rst_stat_bit;
@@ -219,7 +221,8 @@ static int s3c2410wdt_disable_wdt_reset(struct s3c2410_wdt *wdt, bool mask)
 static int s3c2410wdt_mask_wdt_reset(struct s3c2410_wdt *wdt, bool mask)
 {
 	const u32 mask_val = BIT(wdt->drv_data->mask_bit);
-	const u32 val = mask ? mask_val : 0;
+	const bool val_inv = wdt->drv_data->mask_reset_inv;
+	const u32 val = (mask ^ val_inv) ? mask_val : 0;
 	int ret;
 
 	ret = regmap_update_bits(wdt->pmureg, wdt->drv_data->mask_reset_reg,