Input: cros_ec_keyb - add an EC event for sysrq

Some form factors (detachables/tablets) may not have a keyboard and
thus user may have to resort to using a defined EC UI to send sysrq(s)
to the kernel in order to collect crash info etc. This UI typically
is in the form of user pressing volume / power buttons in some specific
sequence and for some specific time. Add a new EC event that allows EC
to communicate the sysrq to the AP.

(We're skipping event number 5 because it has been reserved for
something else)
Signed-off-by: Rajat Jain <rajatja@google.com>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

drivers/input/keyboard/cros_ec_keyb.c

@@ -30,6 +30,7 @@
 #include <linux/notifier.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/sysrq.h>
 #include <linux/input/matrix_keypad.h>
 #include <linux/mfd/cros_ec.h>
 #include <linux/mfd/cros_ec_commands.h>
@@ -260,6 +261,12 @@ static int cros_ec_keyb_work(struct notifier_block *nb,
 				     ckdev->ec->event_size);
 		break;
 
+	case EC_MKBP_EVENT_SYSRQ:
+		val = get_unaligned_le32(&ckdev->ec->event_data.data.sysrq);
+		dev_dbg(ckdev->dev, "sysrq code from EC: %#x\n", val);
+		handle_sysrq(val);
+		break;
+
 	case EC_MKBP_EVENT_BUTTON:
 	case EC_MKBP_EVENT_SWITCH:
 		/*

include/linux/mfd/cros_ec_commands.h

@@ -2040,6 +2040,9 @@ enum ec_mkbp_event {
 	/* The state of the switches have changed. */
 	EC_MKBP_EVENT_SWITCH = 4,
 
+	/* EC sent a sysrq command */
+	EC_MKBP_EVENT_SYSRQ = 6,
+
 	/* Number of MKBP events */
 	EC_MKBP_EVENT_COUNT,
 };
@@ -2052,6 +2055,7 @@ union ec_response_get_next_data {
 
 	uint32_t   buttons;
 	uint32_t   switches;
+	uint32_t   sysrq;
 } __packed;
 
 struct ec_response_get_next_event {