irq/occ/opal: Add self-sent dummy interrupt

This makes OPAL use the OCC interrupt facility to send itself an interrupt
whenever the OPAL event bit is set as a result of an OPAL call that wasn't
itself opal_handle_interrupt() or opal_handle_hmi() (both of which we know
the OS will already deal with appropriately).

This ensures that OPAL event changes are notified to Linux via its
interrupt path which is necessary for it to properly broadcast the state
change to its various clients.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>

7 files changed, 70 insertions, 5 deletions

diff --git a/asm/asm-offsets.c b/asm/asm-offsets.c
index 3440054..e33c181 100644
--- a/asm/asm-offsets.c
+++ b/asm/asm-offsets.c
@@ -35,6 +35,7 @@ int main(void)
 	OFFSET(CPUTHREAD_PIR, cpu_thread, pir);
 	OFFSET(CPUTHREAD_SAVE_R1, cpu_thread, save_r1);
 	OFFSET(CPUTHREAD_STATE, cpu_thread, state);
+	OFFSET(CPUTHREAD_CUR_TOKEN, cpu_thread, current_token);
 
 	OFFSET(STACK_TYPE,	stack_frame, type);
 	OFFSET(STACK_LOCALS,	stack_frame, locals);
diff --git a/asm/head.S b/asm/head.S
index 37a059d..a56f2bb 100644
--- a/asm/head.S
+++ b/asm/head.S
@@ -777,6 +777,9 @@ opal_entry:
 	/* Get the CPU thread */
 	GET_CPU()
 
+	/* Store token in CPU thread */
+	std	%r0,CPUTHREAD_CUR_TOKEN(%r13)
+
 	/* Mark the stack frame */
 	li	%r12,STACK_ENTRY_OPAL_API	
 	std	%r12,STACK_TYPE(%r1)
diff --git a/core/opal.c b/core/opal.c
index 4ad322c..f6bd00d 100644
--- a/core/opal.c
+++ b/core/opal.c
@@ -157,11 +157,26 @@ void opal_update_pending_evt(uint64_t evt_mask, uint64_t evt_values)
 	/* XXX FIXME: Use atomics instead ??? Or caller locks (con_lock ?) */
 	lock(&evt_lock);
 	new_evts = (opal_pending_events & ~evt_mask) | evt_values;
+	if (opal_pending_events != new_evts) {
+		uint64_t tok;
+
 #ifdef OPAL_TRACE_EVT_CHG
-	printf("OPAL: Evt change: 0x%016llx -> 0x%016llx\n",
-	       opal_pending_events, new_evts);
+		printf("OPAL: Evt change: 0x%016llx -> 0x%016llx\n",
+		       opal_pending_events, new_evts);
 #endif
-	opal_pending_events = new_evts;
+		/*
+		 * If an event gets *set* while we are in a different call chain
+		 * than opal_handle_interrupt() or opal_handle_hmi(), then we
+		 * artificially generate an interrupt (OCC interrupt specifically)
+		 * to ensure that Linux properly broadcast the event change internally
+		 */
+		if ((new_evts & ~opal_pending_events) != 0) {
+			tok = this_cpu()->current_token;
+			if (tok != OPAL_HANDLE_INTERRUPT && tok != OPAL_HANDLE_HMI)
+				occ_send_dummy_interrupt();
+		}
+		opal_pending_events = new_evts;
+	}
 	unlock(&evt_lock);
 }
 
diff --git a/hw/occ.c b/hw/occ.c
index f1a7a27..74c9deb 100644
--- a/hw/occ.c
+++ b/hw/occ.c
@@ -480,6 +480,48 @@ static struct fsp_client fsp_occ_client = {
 	.message = fsp_occ_msg,
 };
 
+#define OCB_OCI_OCCMISC		0x6a020
+#define OCB_OCI_OCCMISC_AND	0x6a021
+#define OCB_OCI_OCCMISC_OR	0x6a022
+#define OCB_OCI_OCIMISC_IRQ		PPC_BIT(0)
+#define OCB_OCI_OCIMISC_IRQ_TMGT	PPC_BIT(1)
+#define OCB_OCI_OCIMISC_IRQ_OPAL_DUMMY	PPC_BIT(15)
+
+void occ_send_dummy_interrupt(void)
+{
+	xscom_writeme(OCB_OCI_OCCMISC_OR,
+		      OCB_OCI_OCIMISC_IRQ |
+		      OCB_OCI_OCIMISC_IRQ_OPAL_DUMMY);
+}
+
+static void occ_tmgt_interrupt(void)
+{
+	/* Not currently expected */
+	printf("OCC: TMGT interrupt !\n");
+}
+
+void occ_interrupt(void)
+{
+	uint64_t ireg;
+	int64_t rc;
+
+	/* The OCC interrupt is used to mux up to 15 different sources */
+	rc = xscom_readme(OCB_OCI_OCCMISC, &ireg);
+	if (rc) {
+		prerror("OCC: Failed to read interrupt status !\n");
+		/* Should we mask it in the XIVR ? */
+		return;
+	}
+	prlog(PR_TRACE, "OCC: IRQ received: %04llx\n", ireg >> 48);
+
+	/* Clear the bits */
+	xscom_writeme(OCB_OCI_OCCMISC_AND, ~ireg);
+
+	/* Dispatch */
+	if (ireg & OCB_OCI_OCIMISC_IRQ_TMGT)
+		occ_tmgt_interrupt();
+}
+
 void occ_fsp_init(void)
 {
 	/* OCC is P8 only */
diff --git a/hw/psi.c b/hw/psi.c
index 6752bf4..b96b611 100644
--- a/hw/psi.c
+++ b/hw/psi.c
@@ -276,7 +276,7 @@ static void handle_extra_interrupt(struct psi *psi)
 	 * when available.
 	 */
 	if (val & PSIHB_IRQ_STAT_OCC)
-		printf("PSI: OCC irq received\n");
+		occ_interrupt();
 	if (val & PSIHB_IRQ_STAT_FSI)
 		printf("PSI: FSI irq received\n");
 	if (val & PSIHB_IRQ_STAT_LPC)
diff --git a/include/cpu.h b/include/cpu.h
index 1f92b9c..7895e96 100644
--- a/include/cpu.h
+++ b/include/cpu.h
@@ -58,6 +58,7 @@ struct cpu_thread {
 	bool				con_need_flush;
 	uint32_t			hbrt_spec_wakeup; /* primary only */
 	uint64_t			save_l2_fir_action1;
+	uint64_t			current_token;
 
 	struct lock			job_lock;
 	struct list_head		job_queue;
diff --git a/include/skiboot.h b/include/skiboot.h
index 41180ae..1a1f96f 100644
--- a/include/skiboot.h
+++ b/include/skiboot.h
@@ -204,12 +204,15 @@ extern void nvram_read_complete(bool success);
 struct flash_chip;
 extern int flash_nvram_init(struct flash_chip *chip, uint32_t start,
 			    uint32_t size);
-
 /* UART stuff */
 extern void uart_irq(void);
 extern void uart_setup_linux_passthrough(void);
 extern void uart_setup_opal_console(void);
 
+/* OCC interrupt */
+extern void occ_interrupt(void);
+extern void occ_send_dummy_interrupt(void);
+
 /* Flatten device-tree */
 extern void *create_dtb(const struct dt_node *root);