Initial commit

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

4 files changed, 660 insertions, 0 deletions

diff --git a/LICENSE b/LICENSE
new file mode 100644
index 0000000..8f71f43
--- /dev/null
+++ b/LICENSE
@@ -0,0 +1,202 @@
+                                 Apache License
+                           Version 2.0, January 2004
+                        http://www.apache.org/licenses/
+
+   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION
+
+   1. Definitions.
+
+      "License" shall mean the terms and conditions for use, reproduction,
+      and distribution as defined by Sections 1 through 9 of this document.
+
+      "Licensor" shall mean the copyright owner or entity authorized by
+      the copyright owner that is granting the License.
+
+      "Legal Entity" shall mean the union of the acting entity and all
+      other entities that control, are controlled by, or are under common
+      control with that entity. For the purposes of this definition,
+      "control" means (i) the power, direct or indirect, to cause the
+      direction or management of such entity, whether by contract or
+      otherwise, or (ii) ownership of fifty percent (50%) or more of the
+      outstanding shares, or (iii) beneficial ownership of such entity.
+
+      "You" (or "Your") shall mean an individual or Legal Entity
+      exercising permissions granted by this License.
+
+      "Source" form shall mean the preferred form for making modifications,
+      including but not limited to software source code, documentation
+      source, and configuration files.
+
+      "Object" form shall mean any form resulting from mechanical
+      transformation or translation of a Source form, including but
+      not limited to compiled object code, generated documentation,
+      and conversions to other media types.
+
+      "Work" shall mean the work of authorship, whether in Source or
+      Object form, made available under the License, as indicated by a
+      copyright notice that is included in or attached to the work
+      (an example is provided in the Appendix below).
+
+      "Derivative Works" shall mean any work, whether in Source or Object
+      form, that is based on (or derived from) the Work and for which the
+      editorial revisions, annotations, elaborations, or other modifications
+      represent, as a whole, an original work of authorship. For the purposes
+      of this License, Derivative Works shall not include works that remain
+      separable from, or merely link (or bind by name) to the interfaces of,
+      the Work and Derivative Works thereof.
+
+      "Contribution" shall mean any work of authorship, including
+      the original version of the Work and any modifications or additions
+      to that Work or Derivative Works thereof, that is intentionally
+      submitted to Licensor for inclusion in the Work by the copyright owner
+      or by an individual or Legal Entity authorized to submit on behalf of
+      the copyright owner. For the purposes of this definition, "submitted"
+      means any form of electronic, verbal, or written communication sent
+      to the Licensor or its representatives, including but not limited to
+      communication on electronic mailing lists, source code control systems,
+      and issue tracking systems that are managed by, or on behalf of, the
+      Licensor for the purpose of discussing and improving the Work, but
+      excluding communication that is conspicuously marked or otherwise
+      designated in writing by the copyright owner as "Not a Contribution."
+
+      "Contributor" shall mean Licensor and any individual or Legal Entity
+      on behalf of whom a Contribution has been received by Licensor and
+      subsequently incorporated within the Work.
+
+   2. Grant of Copyright License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      copyright license to reproduce, prepare Derivative Works of,
+      publicly display, publicly perform, sublicense, and distribute the
+      Work and such Derivative Works in Source or Object form.
+
+   3. Grant of Patent License. Subject to the terms and conditions of
+      this License, each Contributor hereby grants to You a perpetual,
+      worldwide, non-exclusive, no-charge, royalty-free, irrevocable
+      (except as stated in this section) patent license to make, have made,
+      use, offer to sell, sell, import, and otherwise transfer the Work,
+      where such license applies only to those patent claims licensable
+      by such Contributor that are necessarily infringed by their
+      Contribution(s) alone or by combination of their Contribution(s)
+      with the Work to which such Contribution(s) was submitted. If You
+      institute patent litigation against any entity (including a
+      cross-claim or counterclaim in a lawsuit) alleging that the Work
+      or a Contribution incorporated within the Work constitutes direct
+      or contributory patent infringement, then any patent licenses
+      granted to You under this License for that Work shall terminate
+      as of the date such litigation is filed.
+
+   4. Redistribution. You may reproduce and distribute copies of the
+      Work or Derivative Works thereof in any medium, with or without
+      modifications, and in Source or Object form, provided that You
+      meet the following conditions:
+
+      (a) You must give any other recipients of the Work or
+          Derivative Works a copy of this License; and
+
+      (b) You must cause any modified files to carry prominent notices
+          stating that You changed the files; and
+
+      (c) You must retain, in the Source form of any Derivative Works
+          that You distribute, all copyright, patent, trademark, and
+          attribution notices from the Source form of the Work,
+          excluding those notices that do not pertain to any part of
+          the Derivative Works; and
+
+      (d) If the Work includes a "NOTICE" text file as part of its
+          distribution, then any Derivative Works that You distribute must
+          include a readable copy of the attribution notices contained
+          within such NOTICE file, excluding those notices that do not
+          pertain to any part of the Derivative Works, in at least one
+          of the following places: within a NOTICE text file distributed
+          as part of the Derivative Works; within the Source form or
+          documentation, if provided along with the Derivative Works; or,
+          within a display generated by the Derivative Works, if and
+          wherever such third-party notices normally appear. The contents
+          of the NOTICE file are for informational purposes only and
+          do not modify the License. You may add Your own attribution
+          notices within Derivative Works that You distribute, alongside
+          or as an addendum to the NOTICE text from the Work, provided
+          that such additional attribution notices cannot be construed
+          as modifying the License.
+
+      You may add Your own copyright statement to Your modifications and
+      may provide additional or different license terms and conditions
+      for use, reproduction, or distribution of Your modifications, or
+      for any such Derivative Works as a whole, provided Your use,
+      reproduction, and distribution of the Work otherwise complies with
+      the conditions stated in this License.
+
+   5. Submission of Contributions. Unless You explicitly state otherwise,
+      any Contribution intentionally submitted for inclusion in the Work
+      by You to the Licensor shall be under the terms and conditions of
+      this License, without any additional terms or conditions.
+      Notwithstanding the above, nothing herein shall supersede or modify
+      the terms of any separate license agreement you may have executed
+      with Licensor regarding such Contributions.
+
+   6. Trademarks. This License does not grant permission to use the trade
+      names, trademarks, service marks, or product names of the Licensor,
+      except as required for reasonable and customary use in describing the
+      origin of the Work and reproducing the content of the NOTICE file.
+
+   7. Disclaimer of Warranty. Unless required by applicable law or
+      agreed to in writing, Licensor provides the Work (and each
+      Contributor provides its Contributions) on an "AS IS" BASIS,
+      WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+      implied, including, without limitation, any warranties or conditions
+      of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A
+      PARTICULAR PURPOSE. You are solely responsible for determining the
+      appropriateness of using or redistributing the Work and assume any
+      risks associated with Your exercise of permissions under this License.
+
+   8. Limitation of Liability. In no event and under no legal theory,
+      whether in tort (including negligence), contract, or otherwise,
+      unless required by applicable law (such as deliberate and grossly
+      negligent acts) or agreed to in writing, shall any Contributor be
+      liable to You for damages, including any direct, indirect, special,
+      incidental, or consequential damages of any character arising as a
+      result of this License or out of the use or inability to use the
+      Work (including but not limited to damages for loss of goodwill,
+      work stoppage, computer failure or malfunction, or any and all
+      other commercial damages or losses), even if such Contributor
+      has been advised of the possibility of such damages.
+
+   9. Accepting Warranty or Additional Liability. While redistributing
+      the Work or Derivative Works thereof, You may choose to offer,
+      and charge a fee for, acceptance of support, warranty, indemnity,
+      or other liability obligations and/or rights consistent with this
+      License. However, in accepting such obligations, You may act only
+      on Your own behalf and on Your sole responsibility, not on behalf
+      of any other Contributor, and only if You agree to indemnify,
+      defend, and hold each Contributor harmless for any liability
+      incurred by, or claims asserted against, such Contributor by reason
+      of your accepting any such warranty or additional liability.
+
+   END OF TERMS AND CONDITIONS
+
+   APPENDIX: How to apply the Apache License to your work.
+
+      To apply the Apache License to your work, attach the following
+      boilerplate notice, with the fields enclosed by brackets "{}"
+      replaced with your own identifying information. (Don't include
+      the brackets!)  The text should be enclosed in the appropriate
+      comment syntax for the file format. We also recommend that a
+      file or class name and description of purpose be included on the
+      same "printed page" as the copyright notice for easier
+      identification within third-party archives.
+
+   Copyright {yyyy} {name of copyright owner}
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+
diff --git a/Makefile.am b/Makefile.am
new file mode 100644
index 0000000..3335e01
--- /dev/null
+++ b/Makefile.am
@@ -0,0 +1,7 @@
+sbin_PROGRAMS = obmc-uart-render-controller
+
+obmc_uart_render_controller_SOURCES = \
+	 uart-render-controller.c
+
+obmc_uart_render_controller_CPPFLAGS = $(LIBSYSTEMD_CFLAGS)
+obmc_uart_render_controller_LDADD = $(LIBSYSTEMD_LIBS)
diff --git a/configure.ac b/configure.ac
new file mode 100644
index 0000000..8a7ced3
--- /dev/null
+++ b/configure.ac
@@ -0,0 +1,17 @@
+AC_PREREQ([2.69])
+AC_INIT([obmc-uart-render-controller], 0.1, [jk@ozlabs.org])
+AM_INIT_AUTOMAKE([subdir-objects -Wall -Werror foreign dist-xz])
+AM_SILENT_RULES([yes])
+
+AC_PROG_CC
+AM_PROG_AR
+AC_PROG_INSTALL
+AC_PROG_MAKE_SET
+
+AX_APPEND_COMPILE_FLAGS([-Wall -Werror], [CFLAGS])
+
+PKG_CHECK_MODULES([LIBSYSTEMD], [libsystemd], [],
+		[AC_MSG_ERROR(["libsystemd required and not found."])])
+
+AC_CONFIG_FILES([Makefile])
+AC_OUTPUT
diff --git a/uart-render-controller.c b/uart-render-controller.c
new file mode 100644
index 0000000..dde6e63
--- /dev/null
+++ b/uart-render-controller.c
@@ -0,0 +1,434 @@
+/**
+ * UART-to-video rendering controller.
+ *
+ * Copyright © 2018 IBM Corporation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define _GNU_SOURCE
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <poll.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <systemd/sd-bus.h>
+
+/*
+ * We monitor two things: host state, and the VGA password register.
+ * State diagram:
+ *
+ *    ┌──────────┐
+ *    │host idle │←──┐
+ *    └──────────┘   │
+ *         │         │
+ *        host      host
+ *         on       !on
+ *         ⭣         │
+ *    ┌──────────┐   │
+ *    │ GPU idle │───┤
+ *    └──────────┘   │
+ *         │         │
+ *       vga pw      │
+ *        set        │
+ *         ⭣         │
+ *    ┌──────────┐   │
+ *    │ running  │───┘
+ *    └──────────┘
+ *
+ * We only want the renderer running while in GPU idle state (host may be
+ * outputting UART data, but isn't yet outputting video). That maps the GPU
+ * state transitions to renderer state transitions as follows:
+ *
+ *  host on:    start renderer
+ *  host !on:   stop renderer
+ *  vga pw set: stop renderer
+ *
+ * Even though there are only two states for the renderer, we keep track of the
+ * three host states, so we know when to monitor the VGA pw register.
+ */
+
+enum host_state {
+	STATE_HOST_IDLE,
+	STATE_HOST_GPU_IDLE,
+	STATE_HOST_GPU_RUNNING,
+};
+
+struct render_ctx {
+	enum host_state	state;
+	int		vga_pw_fd;
+	sd_bus		*bus;
+
+	const char	*service_name;
+};
+
+static const int scratch_poll_ms = 100;
+
+static const char *host_bus_name = "xyz.openbmc_project.State.Host";
+static const char *host_iface_name = "xyz.openbmc_project.State.Host";
+static const char *host_obj_path = "/xyz/openbmc_project/state/host0";
+static const char *host_state_prop = "CurrentHostState";
+static const char *host_state_prop_running =
+	"xyz.openbmc_project.State.Host.HostState.Running";
+
+static const char *dbus_iface_props = "org.freedesktop.DBus.Properties";
+
+static const char *systemd_bus_name = "org.freedesktop.systemd1";
+static const char *systemd_obj = "/org/freedesktop/systemd1";
+static const char *systemd_iface = "org.freedesktop.systemd1.Manager";
+
+static void set_renderer_running(struct render_ctx *ctx, bool running)
+{
+	sd_bus_error e = {0};
+	int rc;
+
+	fprintf(stderr, "setting render state to %s\n",
+			running ? "running" : "stopped");
+
+	rc = sd_bus_call_method(ctx->bus,
+			systemd_bus_name,
+			systemd_obj,
+			systemd_iface,
+			running ? "StartUnit" : "StopUnit",
+			&e,
+			NULL,
+			"ss",
+			ctx->service_name,
+			"replace");
+
+	if (rc < 0)
+		warnx("failed to %s %s: %s\n",
+				running ? "start" : "stop",
+				ctx->service_name,
+				sd_bus_error_is_set(&e) ?
+					e.name : strerror(rc));
+}
+
+static int read_vga_pw_reg(struct render_ctx *ctx, uint8_t *regp)
+{
+	unsigned long tmp;
+	char buf[8];
+	int rc;
+
+	rc = lseek(ctx->vga_pw_fd, 0, SEEK_SET);
+	if (rc == -1) {
+		warn("Can't seek VGA scratch reg interface");
+		return -1;
+	}
+
+	rc = read(ctx->vga_pw_fd, buf, sizeof(buf));
+	if (rc < 1) {
+		warn("Can't read VGA scratch register");
+		return -1;
+	}
+
+	errno = 0;
+	tmp = strtoul(buf, NULL, 0);
+	if (errno || (tmp & ~0xfful)) {
+		warn("Can't parse VGA scratch register value");
+		return -1;
+	}
+
+	*regp = tmp & 0xff;
+
+	return 0;
+}
+
+static void handle_gpu_state(struct render_ctx *ctx, bool running)
+{
+	switch (ctx->state) {
+	case STATE_HOST_GPU_IDLE:
+		if (running) {
+			set_renderer_running(ctx, false);
+			ctx->state = STATE_HOST_GPU_RUNNING;
+		}
+		break;
+	case STATE_HOST_GPU_RUNNING:
+		/* we don't transition here, as the host will never cede
+		 * control of the GPU while running */
+		break;
+	case STATE_HOST_IDLE:
+		/* can't have the GPU running with the host off */
+		break;
+	}
+}
+
+static void query_scratch_reg_state(struct render_ctx *ctx)
+{
+	bool gpu_running;
+	uint8_t reg;
+	int rc;
+
+	rc = read_vga_pw_reg(ctx, &reg);
+	if (rc) {
+		warnx("error reading VGA scratch register, assuming active");
+		gpu_running = true;
+	} else {
+		gpu_running = reg == 0xa8;
+	}
+
+	handle_gpu_state(ctx, gpu_running);
+}
+
+static void handle_host_state(struct render_ctx *ctx, bool running)
+{
+	switch (ctx->state) {
+	case STATE_HOST_IDLE:
+		if (running) {
+			ctx->state = STATE_HOST_GPU_IDLE;
+			query_scratch_reg_state(ctx);
+			if (ctx->state == STATE_HOST_GPU_IDLE)
+				set_renderer_running(ctx, true);
+		}
+		break;
+
+	case STATE_HOST_GPU_IDLE:
+	case STATE_HOST_GPU_RUNNING:
+		if (!running) {
+			ctx->state = STATE_HOST_IDLE;
+			set_renderer_running(ctx, false);
+		}
+		break;
+	}
+}
+
+static bool host_state_is_running(const char *state)
+{
+	return !strcmp(state, host_state_prop_running);
+}
+
+/* returns:
+ *  <0 on message error
+ *   0 if the property isn't applicable
+ *   1 if the property was processed
+ */
+static int handle_host_propchange_entry(struct render_ctx *ctx,
+		sd_bus_message *m)
+{
+	const char *name, *type, *val;
+	char c;
+	int rc;
+
+	rc = sd_bus_message_enter_container(m,
+			SD_BUS_TYPE_DICT_ENTRY, "sv");
+	if (rc <= 0)
+		return -1;
+
+	rc = sd_bus_message_read_basic(m, SD_BUS_TYPE_STRING, &name);
+	if (rc < 0)
+		goto out_exit;
+
+	/* is this a host state change? */
+	if (strcmp(name, host_state_prop)) {
+		rc = 0;
+		goto out_exit;
+	}
+
+	rc = sd_bus_message_peek_type(m, &c, &type);
+	if (rc < 0)
+		goto out_exit;
+
+	/* host state change should be a string, but be paranoid and check
+	 * anyway */
+	if (c != SD_BUS_TYPE_VARIANT || *type != SD_BUS_TYPE_STRING) {
+		char skip_type[] = { c, '\0' };
+		sd_bus_message_skip(m, skip_type);
+		rc = 0;
+		goto out_exit;
+	}
+
+	rc = sd_bus_message_enter_container(m, SD_BUS_TYPE_VARIANT, type);
+	if (rc < 0)
+		goto out_exit;
+
+	rc = sd_bus_message_read_basic(m, SD_BUS_TYPE_STRING, &val);
+	if (rc >= 0) {
+		handle_host_state(ctx, host_state_is_running(val));
+		rc = 1;
+	}
+
+	sd_bus_message_exit_container(m);
+
+out_exit:
+	sd_bus_message_exit_container(m);
+	return rc;
+}
+static int handle_dbus_signal_host_propchange(sd_bus_message *m,
+		void *data, sd_bus_error *err)
+{
+	struct render_ctx *ctx = data;
+	const char *s;
+	int rc;
+
+	/* check that the member and signature indicate a property
+	 * change event
+	 */
+	if (strcmp(sd_bus_message_get_interface(m), dbus_iface_props))
+		return 0;
+
+	if (strcmp(sd_bus_message_get_member(m), "PropertiesChanged"))
+		return 0;
+
+	/* is the property change part of the state interface? */
+	rc = sd_bus_message_read_basic(m, SD_BUS_TYPE_STRING, &s);
+	if (rc < 0 || strcmp(s, host_iface_name))
+		return 0;
+
+	rc = sd_bus_message_enter_container(m, SD_BUS_TYPE_ARRAY, "{sv}");
+	if (rc < 0)
+		return -1;
+
+	for (;;) {
+		rc = handle_host_propchange_entry(ctx, m);
+		if (rc)
+			break;
+	}
+
+	return 0;
+}
+
+static int handle_dbus_event(struct render_ctx *ctx)
+{
+	int rc;
+
+	for (;;) {
+		rc = sd_bus_process(ctx->bus, NULL);
+
+		if (rc <= 0)
+			return rc;
+	}
+}
+
+static int run_daemon(struct render_ctx *ctx)
+{
+	struct pollfd pollfds[1];
+	int rc, timeout;
+
+	pollfds[0].fd = sd_bus_get_fd(ctx->bus);
+	pollfds[0].events = POLLIN;
+
+	for (;;) {
+		if (ctx->state == STATE_HOST_GPU_IDLE)
+			timeout = scratch_poll_ms;
+		else
+			timeout = -1;
+
+		rc = poll(pollfds, 1, timeout);
+
+		if (rc < 0) {
+			warn("poll failure");
+			return -1;
+		}
+
+		if (pollfds[0].revents)
+			handle_dbus_event(ctx);
+
+		if (ctx->state == STATE_HOST_GPU_IDLE)
+			query_scratch_reg_state(ctx);
+	}
+
+	return 0;
+}
+
+static int query_initial_state(struct render_ctx *ctx)
+{
+	sd_bus_error sd_err = { 0 };
+	char *host_state;
+	int rc;
+
+	ctx->state = STATE_HOST_IDLE;
+
+	rc = sd_bus_get_property_string(ctx->bus,
+			host_bus_name,
+			host_obj_path,
+			host_iface_name,
+			host_state_prop,
+			&sd_err,
+			&host_state);
+
+	if (rc < 0) {
+		warnx("error querying host state: %d, %s\n",
+				rc, sd_err.name);
+		sd_bus_error_free(&sd_err);
+		return rc;
+	}
+
+	handle_host_state(ctx, host_state_is_running(host_state));
+	free(host_state);
+
+	return 0;
+}
+
+static void usage(const char *progname)
+{
+	fprintf(stderr, "usage: %s <VGA-reg> <renderer-service>\n",
+			progname);
+}
+
+
+int main(int argc, char **argv)
+{
+	struct render_ctx _ctx, *ctx;
+	const char *vga_pw_path;
+	char *match;
+	int rc;
+
+	ctx = &_ctx;
+
+	if (argc != 3) {
+		usage(argv[0]);
+		return EXIT_FAILURE;
+	}
+
+	vga_pw_path = argv[1];
+	ctx->service_name = argv[2];
+
+	ctx->vga_pw_fd = open(vga_pw_path, O_RDONLY);
+	if (ctx->vga_pw_fd < 0)
+		err(EXIT_FAILURE, "can't open VGA scratch regs interface at %s",
+				vga_pw_path);
+
+
+	rc = sd_bus_default(&ctx->bus);
+	if (rc < 0)
+		err(EXIT_FAILURE, "can't connect to dbus");
+
+
+	rc = query_initial_state(ctx);
+	if (rc)
+		return EXIT_FAILURE;
+
+	rc = asprintf(&match,
+			"type='signal',path='%s',interface='%s',member='%s'",
+			host_obj_path,
+			dbus_iface_props,
+			"PropertiesChanged");
+
+	if (rc < 0)
+		return EXIT_FAILURE;
+
+	rc = sd_bus_add_match(ctx->bus, NULL, match,
+			handle_dbus_signal_host_propchange, ctx);
+	if (rc < 0)
+		errx(EXIT_FAILURE,
+				"can't establish host property change handler");
+
+	rc = run_daemon(ctx);
+
+	return rc == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+}