ast-io: Rework setup/tear-down of communication with the BMC

It's possible for the platform to configure the BMC with SuperIO
access disabled. Rework the interfaces to report failures if SuperIO is
not enabled, and clean up once we're finished.

Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
Signed-off-by: Stewart Smith <stewart@linux.ibm.com>

1 files changed, 61 insertions, 2 deletions

diff --git a/hw/ast-bmc/ast-io.c b/hw/ast-bmc/ast-io.c
index a5528716..eb80181e 100644
--- a/hw/ast-bmc/ast-io.c
+++ b/hw/ast-bmc/ast-io.c
@@ -119,6 +119,17 @@
 #define BMC_SIO_SCR29_MBOX 0x08
 #define BMC_SIO_SCR29_MEMBOOT 0x10
 
+/*
+ *  SIO Register 0x2d: Platform Flags (normal bit ordering)
+ *
+ *       [ 7 ] Hostboot configures SUART
+ *       [ 6 ] Hostboot configures VUART
+ *       [5:1] Reserved
+ *       [ 0 ] Isolate Service Processor
+ */
+#define BMC_SIO_PLAT_FLAGS 		0x2d
+#define  BMC_SIO_PLAT_ISOLATE_SP 	0x01
+
 enum {
 	BMC_SIO_DEV_NONE	= -1,
 	BMC_SIO_DEV_UART1	= 2,
@@ -310,10 +321,58 @@ static void ast_setup_sio_irq_polarity(void)
 	bmc_sio_put(true);
 }
 
-void ast_io_init(void)
+static bool ast_sio_is_enabled(void)
+{
+	bool enabled;
+
+	lpc_outb(0xa5, 0x2e);
+	lpc_outb(0xa5, 0x2e);
+
+	/* Heuristic attempt to confirm SIO is enabled.
+	 *
+	 * Do two tests of 1 byte, giving a false positive probability of
+	 * 1/65536. Read tests on disabled SIO tended to return 0x60.
+	 */
+	bmc_sio_outb(0x2, 0x07);
+	enabled = bmc_sio_inb(0x07) == 2;
+	if (enabled) {
+		bmc_sio_outb(0xd, 0x07);
+		enabled = bmc_sio_inb(0x07) == 0xd;
+	}
+
+	if (enabled)
+		lpc_outb(0xaa, 0x2e);
+
+	return enabled;
+}
+
+bool ast_sio_init(void)
 {
+	bool enabled = ast_sio_is_enabled();
+
+	prlog(PR_NOTICE, "PLAT: SuperIO is %s\n",
+	      enabled ? "available" : "unavailable!");
+
 	/* Configure all AIO interrupts to level low */
-	ast_setup_sio_irq_polarity();
+	if (enabled)
+		ast_setup_sio_irq_polarity();
+
+	return enabled;
+}
+
+bool ast_can_isolate_sp(void)
+{
+	return bmc_sio_inb(BMC_SIO_PLAT_FLAGS) & BMC_SIO_PLAT_ISOLATE_SP;
+}
+
+bool ast_io_is_rw(void)
+{
+	return !(ast_ahb_readl(LPC_HICRB) & LPC_HICRB_ILPC_DISABLE);
+}
+
+bool ast_io_init(void)
+{
+	return ast_io_is_rw();
 }
 
 bool ast_lpc_fw_is_mbox(void)