soc/intel/{skl,cnl,dnv}: disable PM ACPI timer if chosen

Disable the PM ACPI timer during PMC init, when `USE_PM_ACPI_TIMER` is
disabled. This is done to bring SKL, CNL, DNV in line with the other
platforms, in order to transition handling of the PM timer from FSP to
coreboot in the follow-up changes.

For SKL and CNL, this temporarly redundantly disables the PM Timer,
since FSP does that, too. This redundancy is resolved in the follow-up.

Change-Id: I47280cd670a96c8fa5af107986496234f04e1f77
Signed-off-by: Michael Niewöhner <foss@mniewoehner.de>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/57932
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/src/soc/intel/cannonlake/pmc.c b/src/soc/intel/cannonlake/pmc.c
index d502e06..4c88685 100644
--- a/src/soc/intel/cannonlake/pmc.c
+++ b/src/soc/intel/cannonlake/pmc.c
@@ -118,6 +118,15 @@
 	 * found.
 	 */
 	pmc_set_acpi_mode();
+
+	/*
+	 * Disable ACPI PM timer based on Kconfig
+	 *
+	 * Disabling ACPI PM timer is necessary for XTAL OSC shutdown.
+	 * Disabling ACPI PM timer also switches off TCO.
+	 */
+	if (!CONFIG(USE_PM_ACPI_TIMER))
+		setbits8(pmc_mmio_regs() + PCH_PWRM_ACPI_TMR_CTL, ACPI_TIM_DIS);
 }
 
 static void pmc_fill_ssdt(const struct device *dev)