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 <[e-mail]>
Acked-by: Lee Jones <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/keyboard/cros_ec_keyb.c

···
 #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>
···
 		cros_ec_keyb_process(ckdev,
 				     ckdev->ec->event_data.data.key_matrix,
 				     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:

include/linux/mfd/cros_ec_commands.h

···
 	/* 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,
 };
···
 
 	uint32_t   buttons;
 	uint32_t   switches;
+	uint32_t   sysrq;
 } __packed;
 
 struct ec_response_get_next_event {