core: Introduce JAILHOUSE_CON_INVERTED_GATE

Some clock drivers use inverted logic of clock gates. This happens to be
the case for Emtrion's drivers.

Add an additional flag JAILHOUSE_CON_INVERTED_GATE to indicate inverted
logic.

This is necessary if we want to decouple clock gating logic from UART
drivers. The reason behind die decoupling: UART devices are not bound to
a specific clock device. Clock gating should happen independently, but
before initialisation of the UART device.

Signed-off-by: Ralf Ramsauer <ralf.ramsauer@oth-regensburg.de>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

configs/arm/emtrion-rzg1e.c

@@ -41,7 +41,8 @@ struct {
 			/* .divider = 0x2e, */
 			.type = JAILHOUSE_CON_TYPE_HSCIF,
 			.flags =  JAILHOUSE_CON_ACCESS_MMIO |
-				 JAILHOUSE_CON_REGDIST_4,
+				  JAILHOUSE_CON_REGDIST_4 |
+				  JAILHOUSE_CON_INVERTED_GATE,
 		},
 		.platform_info = {
 			/* .pci_mmconfig_base = 0x2000000,

configs/arm/emtrion-rzg1h.c

@@ -41,7 +41,8 @@ struct {
 			/* .divider = 0x2e, */
 			.type= JAILHOUSE_CON_TYPE_SCIFA,
 			.flags = JAILHOUSE_CON_ACCESS_MMIO |
-				 JAILHOUSE_CON_REGDIST_4,
+				 JAILHOUSE_CON_REGDIST_4 |
+				 JAILHOUSE_CON_INVERTED_GATE,
 		},
 		.platform_info = {
 			/* .pci_mmconfig_base = 0x2000000,

configs/arm/emtrion-rzg1m.c

@@ -41,7 +41,8 @@ struct {
 			/* .divider = 0x2e, */
 			.type = JAILHOUSE_CON_TYPE_HSCIF,
 			.flags = JAILHOUSE_CON_ACCESS_MMIO |
-				 JAILHOUSE_CON_REGDIST_4,
+				 JAILHOUSE_CON_REGDIST_4 |
+				 JAILHOUSE_CON_INVERTED_GATE,
 		},
 		.platform_info = {
 			/* .pci_mmconfig_base = 0x2000000,

include/jailhouse/console.h

@@ -65,6 +65,15 @@
 
 #define CON_USES_REGDIST_1(flags) (((flags) & JAILHOUSE_CON_REGDIST_4) == 0)
 
+/* Bits 2-11: Reserved */
+
+/* Bit 12 is used to indicate to clear instead of to set the clock gate */
+#define JAILHOUSE_CON_INVERTED_GATE	0x1000
+
+#define CON_HAS_INVERTED_GATE(flags)	!!((flags) & JAILHOUSE_CON_INVERTED_GATE)
+
+/* Bits 13-15: Reserved */
+
 struct jailhouse_console {
 	__u64 address;
 	__u32 size;