panel-poweroff.patch -- NetBSD 11.0/i386: power a Whistle InterJet off on
"shutdown -p" by sending ESC X to its front panel (com1), once every file
system is unmounted, and only with machdep.interjet_escx=1 and DCD low,
that is, mains absent.  Enable with "options INTERJET_PANEL_POWEROFF".
Apply in usr/src with: patch -p0

Author: Royce Williams
License: the same terms as each NetBSD source file it modifies.

--- sys/arch/i386/conf/files.i386.orig
+++ sys/arch/i386/conf/files.i386
@@ -45,6 +45,12 @@
 defparam 	opt_beep.h		BEEP_ONHALT_PITCH=1500
 defparam 	opt_beep.h		BEEP_ONHALT_PERIOD=250
 
+# Power a Whistle InterJet off from shutdown -p: ESC X to the front panel
+# (com1) in cpu_reboot().
+# _TEST reads DCD inverted, for a QEMU control kernel only.
+defflag	opt_interjet_poweroff.h	INTERJET_PANEL_POWEROFF
+defflag	opt_interjet_poweroff.h	INTERJET_PANEL_POWEROFF_TEST
+
 # Multiboot support
 defflag 	opt_multiboot.h		MULTIBOOT
 obsolete 	defparam		MULTIBOOT_SYMTAB_SPACE
--- sys/arch/i386/i386/machdep.c.orig
+++ sys/arch/i386/i386/machdep.c
@@ -74,6 +74,7 @@
 #include "opt_compat_netbsd.h"
 #include "opt_cpureset_delay.h"
 #include "opt_ddb.h"
+#include "opt_interjet_poweroff.h"
 #include "opt_kgdb.h"
 #include "opt_mtrr.h"
 #include "opt_modular.h"
@@ -805,6 +806,118 @@
 	splx(s);
 }
 
+#ifdef INTERJET_PANEL_POWEROFF
+#include <dev/ic/comreg.h>		/* com_lcr, com_msr, LCR_DLAB, MSR_DCD */
+
+/*
+ * interjet_panel_poweroff:
+ * Local change.  Power a Whistle
+ * InterJet off on shutdown -p by sending ESC X, 1b 58, to the front
+ * panel, com1 at 0x2f8.  With mains absent the panel cuts power at once
+ * and the machine stays off; with mains present it power-CYCLES the
+ * machine, so ESC X is sent only while DCD, the panel's mains-present
+ * line, is low.  WhistleWare's kernel sent the same two bytes at the
+ * same point in its boot(): after the sync, after vfs_unmountall() and a
+ * 100 ms settle, on a power-off only.
+ *
+ * It sends only when all of these hold.  Otherwise it prints which one
+ * failed and returns, and the machine halts as it would without it.
+ *   - machdep.interjet_escx is 1.  It is 0 at boot; rc.d/lcdhalt sets it
+ *     during shutdown -p when /etc/rc.conf has lcdhalt_escx=YES.
+ *   - No file system is mounted.  cpu_reboot() has unmounted them all by
+ *     now, except after a panic, RB_NOSYNC or a cold halt, which skip the
+ *     unmount.  _mountlist_next() reads the list unlocked, which its
+ *     comment reserves for DDB, where nothing else can change the list;
+ *     that holds here too: one CPU, IPL_HIGH, every process killed by
+ *     halt(8).  The locked iterator allocates and takes an adaptive
+ *     mutex, neither of which belongs at IPL_HIGH.
+ *   - The UART is there and DLAB is clear.  An absent UART reads 0xff;
+ *     with DLAB set a data write would load the divisor.
+ *   - DCD is low twice, before and after the 100 ms settle.  An absent
+ *     UART reads 0xff in MSR too, so it reads as mains present.
+ *
+ * Write only, and never the rate: the firmware's 57600 stands.  com(4)
+ * has detached by now, and the data register is never read.  Each byte
+ * waits for THRE with the bound com_common_putc() uses.  ESC W, one bit
+ * away, arms the panel's reset watchdog, so the two bytes are a const
+ * array and nothing else is sent.
+ *
+ * INTERJET_PANEL_POWEROFF_TEST inverts the DCD reading so the send path
+ * runs under QEMU, whose UART reports DCD high.
+ * NEVER put it in a unit's config: on hardware it sends ESC X with mains
+ * present, and the machine power-cycles.
+ *
+ * Author: Royce Williams
+ */
+#define IJPOFF_BASE	IO_COM2		/* 0x2f8, com1, the panel */
+#define IJPOFF_TIMO	150000		/* LSR polls per byte */
+
+int interjet_escx = 0;			/* machdep.interjet_escx */
+
+SYSCTL_SETUP(sysctl_interjet_escx_setup, "machdep.interjet_escx")
+{
+	sysctl_createv(clog, 0, NULL, NULL,
+	    CTLFLAG_PERMANENT | CTLFLAG_READWRITE, CTLTYPE_INT,
+	    "interjet_escx",
+	    SYSCTL_DESCR("Send ESC X to the InterJet panel on power-off "
+	    "when mains is absent"),
+	    NULL, 0, &interjet_escx, 0, CTL_MACHDEP, CTL_CREATE, CTL_EOL);
+}
+
+static void
+interjet_panel_poweroff(void)
+{
+	static const uint8_t escx[] = { 0x1b, 'X' };
+	uint8_t lcr, msr;
+	u_int i, t;
+
+	if (interjet_escx == 0) {
+		printf("interjet: machdep.interjet_escx is 0: "
+		    "ESC X not sent\n");
+		return;
+	}
+	if (_mountlist_next(NULL) != NULL) {
+		printf("interjet: a file system is still mounted: "
+		    "ESC X not sent\n");
+		return;
+	}
+	lcr = inb(IJPOFF_BASE + com_lcr);
+	if (lcr == 0xff || (lcr & LCR_DLAB) != 0) {
+		printf("interjet: no usable UART at 0x%x (lcr 0x%02x): "
+		    "ESC X not sent\n", IJPOFF_BASE, lcr);
+		return;
+	}
+	for (i = 0; i < 2; i++) {
+		if (i == 1)
+			delay(100000);		/* WhistleWare's 100 ms settle */
+		msr = inb(IJPOFF_BASE + com_msr);
+#ifdef INTERJET_PANEL_POWEROFF_TEST
+		msr ^= MSR_DCD;			/* QEMU control only */
+#endif
+		if ((msr & MSR_DCD) != 0) {
+			printf("interjet: DCD high (msr 0x%02x), mains present: "
+			    "ESC X not sent\n", msr);
+			return;
+		}
+	}
+	printf("Sending the power down signal...\n");	/* WhistleWare's */
+	for (i = 0; i < __arraycount(escx); i++) {
+		for (t = IJPOFF_TIMO; t > 0; t--)
+			if ((inb(IJPOFF_BASE + com_lsr) & LSR_TXRDY) != 0)
+				break;
+		if (t == 0) {
+			printf("interjet: UART never drained after %u of 2 "
+			    "bytes\n", i);
+			return;
+		}
+		outb(IJPOFF_BASE + com_data, escx[i]);
+	}
+	/* Mains absent: the power goes within milliseconds. */
+	delay(2000000);
+	printf("interjet: ESC X sent, and the power is still on\n");
+}
+#endif /* INTERJET_PANEL_POWEROFF */
+
 void
 cpu_reboot(int howto, char *bootstr)
 {
@@ -853,6 +966,9 @@
 	doshutdownhooks();
 
 	if ((howto & RB_POWERDOWN) == RB_POWERDOWN) {
+#ifdef INTERJET_PANEL_POWEROFF
+		interjet_panel_poweroff();
+#endif
 #if NACPICA > 0
 		if (s != IPL_NONE)
 			splx(s);