Support for Naples LPC serial interrupts

This adds support for the HW SerIRQ deserializer of the P8 LPC
bridge which is properly wired up on Naples. It also adds support
for detecting and reporting LPC error interrupts on all P8s.

On most platforms (Rhesus is the exception here due to the way it
lets Linux handle the UART interrupts directly), we modify the
device-tree to properly represent the LPC controller as a cascaded
interrupt-controller and the "interrupts" property of LPC devices
to contain the actual LPC interrupt number for the device.

We add a mechanism for drivers to register specific LPC interrupts,
and a "workaround" for pre-Naples P8 which platforms can use to call
all of them for when the external FPGA based deserializer is used.

There's also a callback on LPC resets which isn't used yet, we need
a bit more work on the general LPC error handling, but it can be
done a separate patches.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

1 files changed, 15 insertions, 12 deletions

diff --git a/platforms/rhesus/rhesus.c b/platforms/rhesus/rhesus.c
index 7a43b1f4..b597ba02 100644
--- a/platforms/rhesus/rhesus.c
+++ b/platforms/rhesus/rhesus.c
@@ -20,6 +20,7 @@
 #include <lpc.h>
 #include <console.h>
 #include <opal.h>
+#include <interrupts.h>
 #include <libflash/libflash.h>
 #include <libflash/libffs.h>
 #include <libflash/blocklevel.h>
@@ -156,7 +157,7 @@ static void rhesus_init(void)
 	uart_setup_linux_passthrough();
 }
 
-static void rhesus_dt_fixup_uart(struct dt_node *lpc)
+static void rhesus_dt_fixup_uart(struct dt_node *lpc, bool has_irq)
 {
 	/*
 	 * The official OF ISA/LPC binding is a bit odd, it prefixes
@@ -193,14 +194,15 @@ static void rhesus_dt_fixup_uart(struct dt_node *lpc)
 	 */
 	dt_add_property_strings(uart, "device_type", "serial");
 
-	/*
-	 * Add interrupt. This simulates coming from HostBoot which
-	 * does not know our interrupt numbering scheme. Instead, it
-	 * just tells us which chip the interrupt is wired to, it will
-	 * be the PSI "host error" interrupt of that chip. For now we
-	 * assume the same chip as the LPC bus is on.
+	/* Expose the external interrupt if supported
 	 */
-	dt_add_property_cells(uart, "ibm,irq-chip-id", dt_get_chip_id(lpc));
+	if (has_irq) {
+		uint32_t chip_id = dt_get_chip_id(lpc);
+		uint32_t irq = get_psi_interrupt(chip_id) + P8_IRQ_PSI_HOST_ERR;
+		dt_add_property_cells(uart, "interrupts", irq);
+		dt_add_property_cells(uart, "interrupt-parent",
+				      get_ics_phandle());
+	}
 }
 
 /*
@@ -224,7 +226,7 @@ static void rhesus_dt_fixup_rtc(struct dt_node *lpc)
 			      (EC_RTC_BLOCK_SIZE / 128) * 2);
 }
 
-static void rhesus_dt_fixup(void)
+static void rhesus_dt_fixup(bool has_uart_irq)
 {
 	struct dt_node *n, *primary_lpc = NULL;
 
@@ -240,13 +242,14 @@ static void rhesus_dt_fixup(void)
 		return;
 
 	rhesus_dt_fixup_rtc(primary_lpc);
-	rhesus_dt_fixup_uart(primary_lpc);
+	rhesus_dt_fixup_uart(primary_lpc, has_uart_irq);
 }
 
 static bool rhesus_probe(void)
 {
 	const char *model;
 	int rev;
+	bool has_uart_irq = false;
 
 	if (!dt_node_is_compatible(dt_root, "ibm,powernv"))
 		return false;
@@ -264,14 +267,14 @@ static bool rhesus_probe(void)
 		prerror("Rhesus board revision not found !\n");
 
 	/* Add missing bits of device-tree such as the UART */
-	rhesus_dt_fixup();
+	rhesus_dt_fixup(has_uart_irq);
 
 	/*
 	 * Setup UART and use it as console. For now, we
 	 * don't expose the interrupt as we know it's not
 	 * working properly yet
 	 */
-	uart_init(false);
+	uart_init(has_uart_irq);
 
 	return true;
 }