From 847b2b952602576f8c3bab678377ff4a770d2fc8 Mon Sep 17 00:00:00 2001
From: Nicholas Chin <nic.c3.14@gmail.com>
Date: Tue, 18 Jun 2024 21:31:08 -0600
Subject: [PATCH 14/18] ec/dell/mec5035: Route power button event to host

If command 0x3e with an argument of 1 isn't sent to the EC, pressing the
power button results in the EC powering off the system without letting
the OS cleanly shutting itself down. This command and argument tells the
EC to route power button events to the host so that it can determine
what to do.

The EC command was identified from the ec/google/wilco code, which is
used for Dell's Latitude Chromebooks. According to the EC_GOOGLE_WILCO
Kconfig help text, those ECs run a modified version of Dell's typical
Latitude EC firmware, so it is likely that the two firmware
implementations use similar commands. Examining LPC traffic between the
host and the EC on the Latitude E6400 did reveal that the same command
was being sent by the vendor firmware to the EC, but this does not
confirm that it has the same meaning as the command from the Wilco code.
Sending the command using inb/outb calls in a userspace C program while
running coreboot without this patch did allow subsequent power button
events to be handled by the host, confirming that the command was indeed
the same.

Change-Id: I5ded315270c0e1efbbc90cfa9d9d894b872e99a2
Signed-off-by: Nicholas Chin <nic.c3.14@gmail.com>
---
 src/ec/dell/mec5035/mec5035.c | 8 ++++++++
 src/ec/dell/mec5035/mec5035.h | 7 +++++++
 2 files changed, 15 insertions(+)

diff --git a/src/ec/dell/mec5035/mec5035.c b/src/ec/dell/mec5035/mec5035.c
index 85c2ab0140..bdae929a27 100644
--- a/src/ec/dell/mec5035/mec5035.c
+++ b/src/ec/dell/mec5035/mec5035.c
@@ -94,6 +94,13 @@ void mec5035_control_radio(enum ec_radio_dev dev, enum ec_radio_state state)
 	ec_command(CMD_RADIO_CTRL);
 }
 
+void mec5035_power_button_route(enum ec_power_button_route target)
+{
+	u8 buf = (u8)target;
+	write_mailbox_regs(&buf, 2, 1);
+	ec_command(CMD_POWER_BUTTON_TO_HOST);
+}
+
 void mec5035_change_wake(u8 source, enum ec_wake_change change)
 {
 	u8 buf[ACPI_WAKEUP_NUM_ARGS] = {change, source, 0, 0x40};
@@ -121,6 +128,7 @@ static void mec5035_init(struct device *dev)
 	/* Unconditionally use this argument for now as this setting
 	   is probably the most sensible default out of the 3 choices. */
 	mec5035_mouse_touchpad(TP_PS2_MOUSE);
+	mec5035_power_button_route(HOST);
 
 	pc_keyboard_init(NO_AUX_DEVICE);
 
diff --git a/src/ec/dell/mec5035/mec5035.h b/src/ec/dell/mec5035/mec5035.h
index 8d4fded28b..51422598c4 100644
--- a/src/ec/dell/mec5035/mec5035.h
+++ b/src/ec/dell/mec5035/mec5035.h
@@ -11,6 +11,7 @@
 enum mec5035_cmd {
 	CMD_MOUSE_TP = 0x1a,
 	CMD_RADIO_CTRL = 0x2b,
+	CMD_POWER_BUTTON_TO_HOST = 0x3e,
 	CMD_ACPI_WAKEUP_CHANGE = 0x4a,
 	CMD_SLEEP_ENABLE = 0x64,
 	CMD_CPU_OK = 0xc2,
@@ -36,6 +37,11 @@ enum ec_radio_state {
 	RADIO_ON
 };
 
+enum ec_power_button_route {
+	EC = 0,
+	HOST
+};
+
 #define ACPI_WAKEUP_NUM_ARGS 4
 enum ec_wake_change {
 	WAKE_OFF = 0,
@@ -55,6 +61,7 @@ u8 mec5035_mouse_touchpad(enum ec_mouse_setting setting);
 void mec5035_cpu_ok(void);
 void mec5035_early_init(void);
 void mec5035_control_radio(enum ec_radio_dev device, enum ec_radio_state state);
+void mec5035_power_button_route(enum ec_power_button_route target);
 void mec5035_change_wake(u8 source, enum ec_wake_change change);
 void mec5035_sleep_enable(void);
 
-- 
2.39.5

