1 files changed, 54 insertions, 0 deletions
diff --git a/src/mainboard/dell/optiplex_9020/sch5555_ec.c b/src/mainboard/dell/optiplex_9020/sch5555_ec.c
new file mode 100644
index 0000000000..1df5026531
--- /dev/null
+++ b/src/mainboard/dell/optiplex_9020/sch5555_ec.c
@@ -0,0 +1,54 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <arch/io.h>
+#include <device/pnp_ops.h>
+#include <superio/smsc/sch555x/sch555x.h>
+#include "sch5555_ec.h"
+
+uint8_t sch5555_mbox_read(uint8_t addr1, uint16_t addr2)
+{
+	// clear ec-to-host mailbox
+	uint8_t tmp = inb(SCH555x_EMI_IOBASE + 1);
+	outb(tmp, SCH555x_EMI_IOBASE + 1);
+
+	// send address
+	outw(0 | 0x8001, SCH555x_EMI_IOBASE + 2);
+	outw((addr1 * 2) | 0x100, SCH555x_EMI_IOBASE + 4);
+
+	outw(4 | 0x8002, SCH555x_EMI_IOBASE + 2);
+	outl(addr2 << 16, SCH555x_EMI_IOBASE + 4);
+
+	// send message to ec
+	outb(1, SCH555x_EMI_IOBASE);
+
+	// wait for ack
+	for (size_t retry = 0; retry < 0xfff; ++retry)
+		if (inb(SCH555x_EMI_IOBASE + 1) & 1)
+			break;
+
+	// read result
+	outw(4 | 0x8000, SCH555x_EMI_IOBASE + 2);
+	return inb(SCH555x_EMI_IOBASE + 4);
+}
+
+void sch5555_mbox_write(uint8_t addr1, uint16_t addr2, uint8_t val)
+{
+	// clear ec-to-host mailbox
+	uint8_t tmp = inb(SCH555x_EMI_IOBASE + 1);
+	outb(tmp, SCH555x_EMI_IOBASE + 1);
+
+	// send address and value
+	outw(0 | 0x8001, SCH555x_EMI_IOBASE + 2);
+	outw((addr1 * 2) | 0x101, SCH555x_EMI_IOBASE + 4);
+
+	outw(4 | 0x8002, SCH555x_EMI_IOBASE + 2);
+	outl(val | (addr2 << 16), SCH555x_EMI_IOBASE + 4);
+
+	// send message to ec
+	outb(1, SCH555x_EMI_IOBASE);
+
+	// wait for ack
+	for (size_t retry = 0; retry < 0xfff; ++retry)
+		if (inb(SCH555x_EMI_IOBASE + 1) & 1)
+			break;
+}