diff mbox series

[5/7] drivers: misc: add Gateworks System Controller driver

Message ID 20220308002406.22433-6-tharvey@gateworks.com
State Accepted
Commit 8479b9e6c9db6dc0971283c35d59ab07b289be52
Delegated to: Stefano Babic
Headers show
Series Add Gateworks System Controller driver | expand

Commit Message

Tim Harvey March 8, 2022, 12:24 a.m. UTC
Add a driver for the Gateworks System Controller used on Gateworks boards
which provides a boot watchdog, power control, temperature monitor,
and voltage ADCs.

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
---
 MAINTAINERS           |   6 +
 drivers/misc/Kconfig  |   8 +
 drivers/misc/Makefile |   1 +
 drivers/misc/gsc.c    | 633 ++++++++++++++++++++++++++++++++++++++++++
 include/gsc.h         |  21 ++
 5 files changed, 669 insertions(+)
 create mode 100644 drivers/misc/gsc.c
 create mode 100644 include/gsc.h

Comments

Stefano Babic April 12, 2022, 6:44 p.m. UTC | #1
> Add a driver for the Gateworks System Controller used on Gateworks boards
> which provides a boot watchdog, power control, temperature monitor,
> and voltage ADCs.
> Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Applied to u-boot-imx, master, thanks !

Best regards,
Stefano Babic
diff mbox series

Patch

diff --git a/MAINTAINERS b/MAINTAINERS
index 0f39bc6bc923..a80d2a6f76da 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -853,6 +853,12 @@  T:	git https://source.denx.de/u-boot/custodians/u-boot-fsl-qoriq.git
 F:	drivers/watchdog/sp805_wdt.c
 F:	drivers/watchdog/sbsa_gwdt.c
 
+GATEWORKS_SC
+M:	Tim Harvey <tharvey@gateworks.com>
+S:	Maintained
+F:	drivers/misc/gsc.c
+F:	include/gsc.h
+
 I2C
 M:	Heiko Schocher <hs@denx.de>
 S:	Maintained
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 7029bb7b5c58..10fd601278ef 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -46,6 +46,14 @@  config ATSHA204A
 	   CryptoAuthentication module found for example on the Turris Omnia
 	   board.
 
+config GATEWORKS_SC
+	bool "Gateworks System Controller Support"
+	depends on MISC
+	help
+	  Enable access for the Gateworks System Controller used on Gateworks
+	  boards to provide a boot watchdog, power control, temperature monitor,
+	  voltage ADCs, and EEPROM.
+
 config ROCKCHIP_EFUSE
         bool "Rockchip e-fuse support"
 	depends on MISC
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index f22eff601a1e..6150d01e8840 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -38,6 +38,7 @@  obj-$(CONFIG_FSL_IIM) += fsl_iim.o
 obj-$(CONFIG_FSL_MC9SDZ60) += mc9sdz60.o
 obj-$(CONFIG_FSL_SEC_MON) += fsl_sec_mon.o
 obj-$(CONFIG_$(SPL_)FS_LOADER) += fs_loader.o
+obj-$(CONFIG_GATEWORKS_SC) += gsc.o
 obj-$(CONFIG_GDSYS_IOEP) += gdsys_ioep.o
 obj-$(CONFIG_GDSYS_RXAUI_CTRL) += gdsys_rxaui_ctrl.o
 obj-$(CONFIG_GDSYS_SOC) += gdsys_soc.o
diff --git a/drivers/misc/gsc.c b/drivers/misc/gsc.c
new file mode 100644
index 000000000000..ec24ca807b07
--- /dev/null
+++ b/drivers/misc/gsc.c
@@ -0,0 +1,633 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2022 Gateworks Corporation
+ */
+
+#include <command.h>
+#include <gsc.h>
+#include <i2c.h>
+#include <rtc.h>
+#include <asm/unaligned.h>
+#include <linux/delay.h>
+#include <dm/device.h>
+#include <dm/device-internal.h>
+#include <dm/ofnode.h>
+#include <dm/read.h>
+
+#define GSC_BUSNO	0
+#define GSC_SC_ADDR	0x20
+#define GSC_HWMON_ADDR	0x29
+#define GSC_RTC_ADDR	0x68
+
+/* System Controller registers */
+enum {
+	GSC_SC_CTRL0		= 0,
+	GSC_SC_CTRL1		= 1,
+	GSC_SC_TIME		= 2,
+	GSC_SC_TIME_ADD		= 6,
+	GSC_SC_STATUS		= 10,
+	GSC_SC_FWCRC		= 12,
+	GSC_SC_FWVER		= 14,
+	GSC_SC_WP		= 15,
+	GSC_SC_RST_CAUSE	= 16,
+	GSC_SC_THERM_PROTECT	= 19,
+};
+
+/* System Controller Control1 bits */
+enum {
+	GSC_SC_CTRL1_SLEEP_EN		= 0, /* 1 = enable sleep */
+	GSC_SC_CTRL1_SLEEP_ACTIVATE	= 1, /* 1 = activate sleep */
+	GSC_SC_CTRL1_SLEEP_ADD		= 2, /* 1 = latch and add sleep time */
+	GSC_SC_CTRL1_SLEEP_NOWAKEPB	= 3, /* 1 = do not wake on sleep on button press */
+	GSC_SC_CTRL1_WDTIME		= 4, /* 1 = 60s timeout, 0 = 30s timeout */
+	GSC_SC_CTRL1_WDEN		= 5, /* 1 = enable, 0 = disable */
+	GSC_SC_CTRL1_BOOT_CHK		= 6, /* 1 = enable alt boot check */
+	GSC_SC_CTRL1_WDDIS		= 7, /* 1 = disable boot watchdog */
+};
+
+/* System Controller Interrupt bits */
+enum {
+	GSC_SC_IRQ_PB		= 0, /* Pushbutton switch */
+	GSC_SC_IRQ_SECURE	= 1, /* Secure Key erase operation complete */
+	GSC_SC_IRQ_EEPROM_WP	= 2, /* EEPROM write violation */
+	GSC_SC_IRQ_GPIO		= 4, /* GPIO change */
+	GSC_SC_IRQ_TAMPER	= 5, /* Tamper detect */
+	GSC_SC_IRQ_WATCHDOG	= 6, /* Watchdog trip */
+	GSC_SC_IRQ_PBLONG	= 7, /* Pushbutton long hold */
+};
+
+/* System Controller WP bits */
+enum {
+	GSC_SC_WP_ALL		= 0, /* Write Protect All EEPROM regions */
+	GSC_SC_WP_BOARDINFO	= 1, /* Write Protect Board Info region */
+};
+
+/* System Controller Reset Cause */
+enum {
+	GSC_SC_RST_CAUSE_VIN		= 0,
+	GSC_SC_RST_CAUSE_PB		= 1,
+	GSC_SC_RST_CAUSE_WDT		= 2,
+	GSC_SC_RST_CAUSE_CPU		= 3,
+	GSC_SC_RST_CAUSE_TEMP_LOCAL	= 4,
+	GSC_SC_RST_CAUSE_TEMP_REMOTE	= 5,
+	GSC_SC_RST_CAUSE_SLEEP		= 6,
+	GSC_SC_RST_CAUSE_BOOT_WDT	= 7,
+	GSC_SC_RST_CAUSE_BOOT_WDT_MAN	= 8,
+	GSC_SC_RST_CAUSE_SOFT_PWR	= 9,
+	GSC_SC_RST_CAUSE_MAX		= 10,
+};
+
+#if (IS_ENABLED(CONFIG_DM_I2C))
+
+struct gsc_priv {
+	int gscver;
+	int fwver;
+	int fwcrc;
+	struct udevice *hwmon;
+	struct udevice *rtc;
+};
+
+/*
+ * GSCv2 will fail to ACK an I2C transaction if it is busy, which can occur
+ * during its 1HZ timer tick while reading ADC's. When this does occur,
+ * it will never be busy longer than 2 back-to-back transfers so retry 3 times.
+ */
+static int gsc_i2c_read(struct udevice *dev, uint addr, u8 *buf, int len)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+	int retry = (priv->gscver == 3) ? 1 : 3;
+	int n = 0;
+	int ret;
+
+	while (n++ < retry) {
+		ret = dm_i2c_read(dev, addr, buf, len);
+		if (!ret)
+			break;
+		if (ret != -EREMOTEIO)
+			break;
+		mdelay(10);
+	}
+	return ret;
+}
+
+static int gsc_i2c_write(struct udevice *dev, uint addr, const u8 *buf, int len)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+	int retry = (priv->gscver == 3) ? 1 : 3;
+	int n = 0;
+	int ret;
+
+	while (n++ < retry) {
+		ret = dm_i2c_write(dev, addr, buf, len);
+		if (!ret)
+			break;
+		if (ret != -EREMOTEIO)
+			break;
+		mdelay(10);
+	}
+	return ret;
+}
+
+static struct udevice *gsc_get_dev(int busno, int slave)
+{
+	struct udevice *dev, *bus;
+	int ret;
+
+	ret = uclass_get_device_by_seq(UCLASS_I2C, busno, &bus);
+	if (ret)
+		return NULL;
+	ret = dm_i2c_probe(bus, slave, 0, &dev);
+	if (ret)
+		return NULL;
+
+	return dev;
+}
+
+static int gsc_thermal_get_info(struct udevice *dev, u8 *outreg, int *tmax, bool *enable)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+	int ret;
+	u8 reg;
+
+	if (priv->gscver > 2 && priv->fwver > 52) {
+		ret = gsc_i2c_read(dev, GSC_SC_THERM_PROTECT, &reg, 1);
+		if (!ret) {
+			if (outreg)
+				*outreg = reg;
+			if (tmax) {
+				*tmax = ((reg & 0xf8) >> 3) * 2;
+				if (*tmax)
+					*tmax += 70;
+				else
+					*tmax = 120;
+			}
+			if (enable)
+				*enable = reg & 1;
+		}
+	} else {
+		ret = -ENODEV;
+	}
+
+	return ret;
+}
+
+static int gsc_thermal_get_temp(struct udevice *dev)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+	u32 reg, mode, val;
+	const char *label;
+	ofnode node;
+	u8 buf[2];
+
+	ofnode_for_each_subnode(node, dev_read_subnode(dev, "adc")) {
+		if (ofnode_read_u32(node, "reg", &reg))
+			reg = -1;
+		if (ofnode_read_u32(node, "gw,mode", &mode))
+			mode = -1;
+		label = ofnode_read_string(node, "label");
+
+		if ((reg == -1) || (mode == -1) || !label)
+			continue;
+
+		if (mode != 0 || strcmp(label, "temp"))
+			continue;
+
+		memset(buf, 0, sizeof(buf));
+		if (!gsc_i2c_read(priv->hwmon, reg, buf, sizeof(buf))) {
+			val = buf[0] | buf[1] << 8;
+			if (val > 0x8000)
+				val -= 0xffff;
+			return val;
+		}
+	}
+
+	return 0;
+}
+
+static void gsc_thermal_info(struct udevice *dev)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+
+	switch (priv->gscver) {
+	case 2:
+		printf("board_temp:%dC ", gsc_thermal_get_temp(dev) / 10);
+		break;
+	case 3:
+		if (priv->fwver > 52) {
+			bool enabled;
+			int tmax;
+
+			if (!gsc_thermal_get_info(dev, NULL, &tmax, &enabled)) {
+				puts("Thermal protection:");
+				if (enabled)
+					printf("enabled at %dC ", tmax);
+				else
+					puts("disabled ");
+			}
+		}
+		break;
+	}
+}
+
+static void gsc_reset_info(struct udevice *dev)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+	static const char * const names[] = {
+		"VIN",
+		"PB",
+		"WDT",
+		"CPU",
+		"TEMP_L",
+		"TEMP_R",
+		"SLEEP",
+		"BOOT_WDT1",
+		"BOOT_WDT2",
+		"SOFT_PWR",
+	};
+	u8 reg;
+
+	/* reset cause */
+	switch (priv->gscver) {
+	case 2:
+		if (!gsc_i2c_read(dev, GSC_SC_STATUS, &reg, 1)) {
+			if (reg & BIT(GSC_SC_IRQ_WATCHDOG)) {
+				puts("RST:WDT");
+				reg &= ~BIT(GSC_SC_IRQ_WATCHDOG);
+				gsc_i2c_write(dev, GSC_SC_STATUS, &reg, 1);
+			} else {
+				puts("RST:VIN");
+			}
+			printf(" WDT:%sabled ",
+			       (reg & BIT(GSC_SC_CTRL1_WDEN)) ? "en" : "dis");
+		}
+		break;
+	case 3:
+		if (priv->fwver > 52 &&
+		    !gsc_i2c_read(dev, GSC_SC_RST_CAUSE, &reg, 1)) {
+			puts("RST:");
+			if (reg < ARRAY_SIZE(names))
+				printf("%s ", names[reg]);
+			else
+				printf("0x%02x ", reg);
+		}
+		break;
+	}
+}
+
+/* display hardware monitor ADC channels */
+static int gsc_hwmon(struct udevice *dev)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+	u32 reg, mode, val, offset;
+	const char *label;
+	ofnode node;
+	u8 buf[2];
+	u32 r[2];
+	int ret;
+
+	/* iterate over hwmon nodes */
+	ofnode_for_each_subnode(node, dev_read_subnode(dev, "adc")) {
+		if (ofnode_read_u32(node, "reg", &reg))
+			reg = -1;
+		if (ofnode_read_u32(node, "gw,mode", &mode))
+			mode = -1;
+		label = ofnode_read_string(node, "label");
+		if ((reg == -1) || (mode == -1) || !label)
+			continue;
+
+		memset(buf, 0, sizeof(buf));
+		ret = gsc_i2c_read(priv->hwmon, reg, buf, sizeof(buf));
+		if (ret) {
+			printf("i2c error: %d\n", ret);
+			continue;
+		}
+		val = buf[0] | buf[1] << 8;
+
+		switch (mode) {
+		case 0: /* temperature (C*10) */
+			if (val > 0x8000)
+				val -= 0xffff;
+			printf("%-8s: %d.%ldC\n", label, val / 10, abs(val % 10));
+			break;
+		case 1: /* prescaled voltage */
+			if (val != 0xffff)
+				printf("%-8s: %d.%03dV\n", label, val / 1000, val % 1000);
+			break;
+		case 2: /* scaled based on ref volt and resolution */
+			val *= 2500;
+			val /= 1 << 12;
+
+			/* apply pre-scaler voltage divider */
+			if (!ofnode_read_u32_index(node, "gw,voltage-divider-ohms", 0, &r[0]) &&
+			    !ofnode_read_u32_index(node, "gw,voltage-divider-ohms", 1, &r[1]) &&
+			    r[0] && r[1]) {
+				val *= (r[0] + r[1]);
+				val /= r[1];
+			}
+
+			/* adjust by offset */
+			val += (offset / 1000);
+
+			printf("%-8s: %d.%03dV\n", label, val / 1000, val % 1000);
+			break;
+		}
+	}
+
+	return 0;
+}
+
+static int gsc_banner(struct udevice *dev)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+
+	/* banner */
+	printf("GSCv%d   : v%d 0x%04x ", priv->gscver, priv->fwver, priv->fwcrc);
+	gsc_reset_info(dev);
+	gsc_thermal_info(dev);
+	puts("\n");
+
+	/* Display RTC */
+	if (priv->rtc) {
+		u8 buf[4];
+		time_t timestamp;
+		struct rtc_time tm;
+
+		if (!gsc_i2c_read(priv->rtc, 0, buf, 4)) {
+			timestamp = get_unaligned_le32(buf);
+			rtc_to_tm(timestamp, &tm);
+			printf("RTC     : %4d-%02d-%02d  %2d:%02d:%02d UTC\n",
+			       tm.tm_year, tm.tm_mon, tm.tm_mday,
+			       tm.tm_hour, tm.tm_min, tm.tm_sec);
+		}
+	}
+
+	return 0;
+}
+
+static int gsc_probe(struct udevice *dev)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+	u8 buf[32];
+	int ret;
+
+	ret = gsc_i2c_read(dev, 0, buf, sizeof(buf));
+	if (ret)
+		return ret;
+
+	/*
+	 * GSC chip version:
+	 *   GSCv2 has 16 registers (which overlap)
+	 *   GSCv3 has 32 registers
+	 */
+	priv->gscver = memcmp(buf, buf + 16, 16) ? 3 : 2;
+	priv->fwver = buf[GSC_SC_FWVER];
+	priv->fwcrc = buf[GSC_SC_FWCRC] | buf[GSC_SC_FWCRC + 1] << 8;
+	priv->hwmon = gsc_get_dev(GSC_BUSNO, GSC_HWMON_ADDR);
+	if (priv->hwmon)
+		dev_set_priv(priv->hwmon, priv);
+	priv->rtc = gsc_get_dev(GSC_BUSNO, GSC_RTC_ADDR);
+	if (priv->rtc)
+		dev_set_priv(priv->rtc, priv);
+
+#ifdef CONFIG_SPL_BUILD
+	gsc_banner(dev);
+#endif
+
+	return 0;
+};
+
+static const struct udevice_id gsc_ids[] = {
+	{ .compatible = "gw,gsc", },
+	{ }
+};
+
+U_BOOT_DRIVER(gsc) = {
+	.name = "gsc",
+	.id = UCLASS_MISC,
+	.of_match = gsc_ids,
+	.probe = gsc_probe,
+	.priv_auto      = sizeof(struct gsc_priv),
+	.flags = DM_FLAG_PRE_RELOC,
+};
+
+static int gsc_sleep(struct udevice *dev, unsigned long secs)
+{
+	u8 regs[4];
+	int ret;
+
+	printf("GSC Sleeping for %ld seconds\n", secs);
+	put_unaligned_le32(secs, regs);
+	ret = gsc_i2c_write(dev, GSC_SC_TIME_ADD, regs, sizeof(regs));
+	if (ret)
+		goto err;
+	ret = gsc_i2c_read(dev, GSC_SC_CTRL1, regs, 1);
+	if (ret)
+		goto err;
+	regs[0] |= BIT(GSC_SC_CTRL1_SLEEP_ADD);
+	ret = gsc_i2c_write(dev, GSC_SC_CTRL1, regs, 1);
+	if (ret)
+		goto err;
+	regs[0] &= ~BIT(GSC_SC_CTRL1_SLEEP_ADD);
+	regs[0] |= BIT(GSC_SC_CTRL1_SLEEP_EN) | BIT(GSC_SC_CTRL1_SLEEP_ACTIVATE);
+	ret = gsc_i2c_write(dev, GSC_SC_CTRL1, regs, 1);
+	if (ret)
+		goto err;
+
+	return 0;
+
+err:
+	printf("i2c error: %d\n", ret);
+	return ret;
+}
+
+static int gsc_wd_disable(struct udevice *dev)
+{
+	int ret;
+	u8 reg;
+
+	ret = gsc_i2c_read(dev, GSC_SC_CTRL1, &reg, 1);
+	if (ret)
+		goto err;
+	reg |= BIT(GSC_SC_CTRL1_WDDIS);
+	reg &= ~BIT(GSC_SC_CTRL1_BOOT_CHK);
+	ret = gsc_i2c_write(dev, GSC_SC_CTRL1, &reg, 1);
+	if (ret)
+		goto err;
+	puts("GSC     : boot watchdog disabled\n");
+
+	return 0;
+
+err:
+	puts("i2c error");
+	return ret;
+}
+
+static int gsc_thermal(struct udevice *dev, const char *cmd, const char *val)
+{
+	struct gsc_priv *priv = dev_get_priv(dev);
+	int ret, tmax;
+	bool enabled;
+	u8 reg;
+
+	if (priv->gscver < 3 || priv->fwver < 53)
+		return -EINVAL;
+	ret = gsc_thermal_get_info(dev, &reg, &tmax, &enabled);
+	if (ret)
+		return ret;
+	if (cmd && !strcmp(cmd, "enable")) {
+		if (val && *val) {
+			tmax = clamp((int)simple_strtoul(val, NULL, 0), 72, 122);
+			reg &= ~0xf8;
+			reg |= ((tmax - 70) / 2) << 3;
+		}
+		reg |= BIT(0);
+		gsc_i2c_write(dev, GSC_SC_THERM_PROTECT, &reg, 1);
+	} else if (cmd && !strcmp(cmd, "disable")) {
+		reg &= ~BIT(0);
+		gsc_i2c_write(dev, GSC_SC_THERM_PROTECT, &reg, 1);
+	} else if (cmd) {
+		return -EINVAL;
+	}
+
+	/* show status */
+	gsc_thermal_info(dev);
+	puts("\n");
+
+	return 0;
+}
+
+/* override in board files to display additional board EEPROM info */
+__weak void board_gsc_info(void)
+{
+}
+
+static void gsc_info(struct udevice *dev)
+{
+	gsc_banner(dev);
+	board_gsc_info();
+}
+
+static int do_gsc(struct cmd_tbl *cmdtp, int flag, int argc, char * const argv[])
+{
+	struct udevice *dev;
+	int ret;
+
+	/* get/probe driver */
+	ret = uclass_get_device_by_driver(UCLASS_MISC, DM_DRIVER_GET(gsc), &dev);
+	if (ret)
+		return CMD_RET_USAGE;
+	if (argc < 2) {
+		gsc_info(dev);
+		return CMD_RET_SUCCESS;
+	} else if (strcasecmp(argv[1], "sleep") == 0) {
+		if (argc < 3)
+			return CMD_RET_USAGE;
+		if (!gsc_sleep(dev, dectoul(argv[2], NULL)))
+			return CMD_RET_SUCCESS;
+	} else if (strcasecmp(argv[1], "hwmon") == 0) {
+		if (!gsc_hwmon(dev))
+			return CMD_RET_SUCCESS;
+	} else if (strcasecmp(argv[1], "wd-disable") == 0) {
+		if (!gsc_wd_disable(dev))
+			return CMD_RET_SUCCESS;
+	} else if (strcasecmp(argv[1], "thermal") == 0) {
+		char *cmd, *val;
+
+		cmd = (argc > 2) ? argv[2] : NULL;
+		val = (argc > 3) ? argv[3] : NULL;
+		if (!gsc_thermal(dev, cmd, val))
+			return CMD_RET_SUCCESS;
+	}
+
+	return CMD_RET_USAGE;
+}
+
+U_BOOT_CMD(gsc, 4, 1, do_gsc, "Gateworks System Controller",
+	   "[sleep <secs>]|[hwmon]|[wd-disable][thermal [disable|enable [temp]]]\n");
+
+/* disable boot watchdog - useful for an SPL that wants to use falcon mode */
+int gsc_boot_wd_disable(void)
+{
+	struct udevice *dev;
+	int ret;
+
+	/* get/probe driver */
+	ret = uclass_get_device_by_driver(UCLASS_MISC, DM_DRIVER_GET(gsc), &dev);
+	if (!ret)
+		ret = gsc_wd_disable(dev);
+
+	return ret;
+}
+
+# else
+
+/*
+ * GSCv2 will fail to ACK an I2C transaction if it is busy, which can occur
+ * during its 1HZ timer tick while reading ADC's. When this does occur,
+ * it will never be busy longer than 2 back-to-back transfers so retry 3 times.
+ */
+static int gsc_i2c_read(uint chip, uint addr, u8 *buf, int len)
+{
+	int retry = 3;
+	int n = 0;
+	int ret;
+
+	while (n++ < retry) {
+		ret = i2c_read(chip, addr, 1, buf, len);
+		if (!ret)
+			break;
+		if (ret != -EREMOTEIO)
+			break;
+printf("%s 0x%02x retry %d\n", __func__, addr, n);
+		mdelay(10);
+	}
+	return ret;
+}
+
+static int gsc_i2c_write(uint chip, uint addr, u8 *buf, int len)
+{
+	int retry = 3;
+	int n = 0;
+	int ret;
+
+	while (n++ < retry) {
+		ret = i2c_write(chip, addr, 1, buf, len);
+		if (!ret)
+			break;
+		if (ret != -EREMOTEIO)
+			break;
+printf("%s 0x%02x retry %d\n", __func__, addr, n);
+		mdelay(10);
+	}
+	return ret;
+}
+
+/* disable boot watchdog - useful for an SPL that wants to use falcon mode */
+int gsc_boot_wd_disable(void)
+{
+	u8 buf[32];
+	int ret;
+
+	i2c_set_bus_num(GSC_BUSNO);
+	ret = gsc_i2c_read(GSC_SC_ADDR, 0, buf, sizeof(buf));
+	if (!ret) {
+		buf[GSC_SC_CTRL1] |= BIT(GSC_SC_CTRL1_WDDIS);
+		ret = gsc_i2c_write(GSC_SC_ADDR, GSC_SC_CTRL1, &buf[GSC_SC_CTRL1], 1);
+		printf("GSCv%d: v%d 0x%04x ",
+		       memcmp(buf, buf + 16, 16) ? 3 : 2,
+		       buf[GSC_SC_FWVER],
+		       buf[GSC_SC_FWCRC] | buf[GSC_SC_FWCRC + 1] << 8);
+		if (buf[GSC_SC_STATUS] & BIT(GSC_SC_IRQ_WATCHDOG)) {
+			puts("RST:WDT ");
+			buf[GSC_SC_STATUS] &= ~BIT(GSC_SC_IRQ_WATCHDOG);
+			gsc_i2c_write(GSC_SC_ADDR, GSC_SC_STATUS, &buf[GSC_SC_STATUS], 1);
+		} else {
+			puts("RST:VIN ");
+		}
+		puts("WDT:disabled\n");
+	}
+
+	return ret;
+}
+
+#endif
diff --git a/include/gsc.h b/include/gsc.h
new file mode 100644
index 000000000000..132c3121825e
--- /dev/null
+++ b/include/gsc.h
@@ -0,0 +1,21 @@ 
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright 2022 Gateworks Corporation
+ */
+
+#ifndef _GSC_H_
+#define _GSC_H_
+
+/*
+ * board_gsc_info - Display additional board info
+ */
+void board_gsc_info(void);
+
+/*
+ * gsc_boot_wd_disable - disable the BOOT watchdog
+ *
+ * Return: 0 on success or negative error on failure
+ */
+int gsc_boot_wd_disable(void);
+
+#endif