[PATCH v3 4/5] watchdog: Congatec Board Controller watchdog timer driver

[Thomas Richard <thomas.richard@xxxxxxxxxxx>]

Add watchdog timer support for the Congatec Board Controller.

Acked-by: Guenter Roeck <linux@xxxxxxxxxxxx>
Signed-off-by: Thomas Richard <thomas.richard@xxxxxxxxxxx>
---
 drivers/watchdog/Kconfig    |  10 +++
 drivers/watchdog/Makefile   |   1 +
 drivers/watchdog/cgbc_wdt.c | 211 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 222 insertions(+)

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 684b9fe84fff..755cf3559540 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1151,6 +1151,16 @@ config ALIM7101_WDT
 
 	  Most people will say N.
 
+config CGBC_WDT
+	tristate "Congatec Board Controller Watchdog Timer"
+	depends on MFD_CGBC
+	select WATCHDOG_CORE
+	help
+	  Enables watchdog timer support for the Congatec Board Controller.
+
+	  This driver can also be built as a module. If so, the module will be
+	  called cgbc_wdt.
+
 config EBC_C384_WDT
 	tristate "WinSystems EBC-C384 Watchdog Timer"
 	depends on (X86 || COMPILE_TEST) && HAS_IOPORT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index ab6f2b41e38e..386d88d89fe5 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -107,6 +107,7 @@ obj-$(CONFIG_ADVANTECH_WDT) += advantechwdt.o
 obj-$(CONFIG_ADVANTECH_EC_WDT) += advantech_ec_wdt.o
 obj-$(CONFIG_ALIM1535_WDT) += alim1535_wdt.o
 obj-$(CONFIG_ALIM7101_WDT) += alim7101_wdt.o
+obj-$(CONFIG_CGBC_WDT) += cgbc_wdt.o
 obj-$(CONFIG_EBC_C384_WDT) += ebc-c384_wdt.o
 obj-$(CONFIG_EXAR_WDT) += exar_wdt.o
 obj-$(CONFIG_F71808E_WDT) += f71808e_wdt.o
diff --git a/drivers/watchdog/cgbc_wdt.c b/drivers/watchdog/cgbc_wdt.c
new file mode 100644
index 000000000000..702b055ba6f4
--- /dev/null
+++ b/drivers/watchdog/cgbc_wdt.c
@@ -0,0 +1,211 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Congatec Board Controller watchdog driver
+ *
+ * Copyright (C) 2024 Bootlin
+ * Author: Thomas Richard <thomas.richard@xxxxxxxxxxx>
+ */
+
+#include <linux/build_bug.h>
+#include <linux/device.h>
+#include <linux/limits.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#include <linux/mfd/cgbc.h>
+
+#define CGBC_WDT_CMD_TRIGGER	0x27
+#define CGBC_WDT_CMD_INIT	0x28
+#define CGBC_WDT_DISABLE	0x00
+
+#define CGBC_WDT_MODE_SINGLE_EVENT 0x02
+
+#define CGBC_WDT_MIN_TIMEOUT	1
+#define CGBC_WDT_MAX_TIMEOUT	((U32_MAX >> 8) / 1000)
+
+#define CGBC_WDT_DEFAULT_TIMEOUT	30
+#define CGBC_WDT_DEFAULT_PRETIMEOUT	0
+
+enum action {
+	ACTION_INT = 0,
+	ACTION_SMI,
+	ACTION_RESET,
+	ACTION_BUTTON,
+};
+
+static unsigned int timeout;
+module_param(timeout, uint, 0);
+MODULE_PARM_DESC(timeout,
+		 "Watchdog timeout in seconds. (>=0, default="
+		 __MODULE_STRING(CGBC_WDT_DEFAULT_TIMEOUT) ")");
+
+static unsigned int pretimeout = CGBC_WDT_DEFAULT_PRETIMEOUT;
+module_param(pretimeout, uint, 0);
+MODULE_PARM_DESC(pretimeout,
+		 "Watchdog pretimeout in seconds. (>=0, default="
+		 __MODULE_STRING(CGBC_WDT_DEFAULT_PRETIMEOUT) ")");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout,
+		 "Watchdog cannot be stopped once started (default="
+		 __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+struct cgbc_wdt_data {
+	struct cgbc_device_data	*cgbc;
+	struct watchdog_device	wdd;
+};
+
+struct cgbc_wdt_cmd_cfg {
+	u8 cmd;
+	u8 mode;
+	u8 action;
+	u8 timeout1[3];
+	u8 timeout2[3];
+	u8 reserved[3];
+	u8 delay[3];
+} __packed;
+
+static_assert(sizeof(struct cgbc_wdt_cmd_cfg) == 15);
+
+static int cgbc_wdt_start(struct watchdog_device *wdd)
+{
+	struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct cgbc_device_data *cgbc = wdt_data->cgbc;
+	unsigned int timeout1 = (wdd->timeout - wdd->pretimeout) * 1000;
+	unsigned int timeout2 = wdd->pretimeout * 1000;
+	u8 action;
+
+	struct cgbc_wdt_cmd_cfg cmd_start = {
+		.cmd = CGBC_WDT_CMD_INIT,
+		.mode = CGBC_WDT_MODE_SINGLE_EVENT,
+		.timeout1[0] = (u8)timeout1,
+		.timeout1[1] = (u8)(timeout1 >> 8),
+		.timeout1[2] = (u8)(timeout1 >> 16),
+		.timeout2[0] = (u8)timeout2,
+		.timeout2[1] = (u8)(timeout2 >> 8),
+		.timeout2[2] = (u8)(timeout2 >> 16),
+	};
+
+	if (wdd->pretimeout) {
+		action = 2;
+		action |= ACTION_SMI << 2;
+		action |= ACTION_RESET << 4;
+	} else {
+		action = 1;
+		action |= ACTION_RESET << 2;
+	}
+
+	cmd_start.action = action;
+
+	return cgbc_command(cgbc, &cmd_start, sizeof(cmd_start), NULL, 0, NULL);
+}
+
+static int cgbc_wdt_stop(struct watchdog_device *wdd)
+{
+	struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct cgbc_device_data *cgbc = wdt_data->cgbc;
+	struct cgbc_wdt_cmd_cfg cmd_stop = {
+		.cmd = CGBC_WDT_CMD_INIT,
+		.mode = CGBC_WDT_DISABLE,
+	};
+
+	return cgbc_command(cgbc, &cmd_stop, sizeof(cmd_stop), NULL, 0, NULL);
+}
+
+static int cgbc_wdt_keepalive(struct watchdog_device *wdd)
+{
+	struct cgbc_wdt_data *wdt_data = watchdog_get_drvdata(wdd);
+	struct cgbc_device_data *cgbc = wdt_data->cgbc;
+	u8 cmd_ping = CGBC_WDT_CMD_TRIGGER;
+
+	return cgbc_command(cgbc, &cmd_ping, sizeof(cmd_ping), NULL, 0, NULL);
+}
+
+static int cgbc_wdt_set_pretimeout(struct watchdog_device *wdd,
+				   unsigned int pretimeout)
+{
+	wdd->pretimeout = pretimeout;
+
+	if (watchdog_active(wdd))
+		return cgbc_wdt_start(wdd);
+
+	return 0;
+}
+
+static int cgbc_wdt_set_timeout(struct watchdog_device *wdd,
+				unsigned int timeout)
+{
+	if (timeout < wdd->pretimeout)
+		wdd->pretimeout = 0;
+
+	wdd->timeout = timeout;
+
+	if (watchdog_active(wdd))
+		return cgbc_wdt_start(wdd);
+
+	return 0;
+}
+
+static const struct watchdog_info cgbc_wdt_info = {
+	.identity	= "CGBC Watchdog",
+	.options	= WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+		WDIOF_MAGICCLOSE | WDIOF_PRETIMEOUT
+};
+
+static const struct watchdog_ops cgbc_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= cgbc_wdt_start,
+	.stop		= cgbc_wdt_stop,
+	.ping		= cgbc_wdt_keepalive,
+	.set_timeout	= cgbc_wdt_set_timeout,
+	.set_pretimeout = cgbc_wdt_set_pretimeout,
+};
+
+static int cgbc_wdt_probe(struct platform_device *pdev)
+{
+	struct cgbc_device_data *cgbc = dev_get_drvdata(pdev->dev.parent);
+	struct device *dev = &pdev->dev;
+	struct cgbc_wdt_data *wdt_data;
+	struct watchdog_device *wdd;
+
+	wdt_data = devm_kzalloc(dev, sizeof(*wdt_data), GFP_KERNEL);
+	if (!wdt_data)
+		return -ENOMEM;
+
+	wdt_data->cgbc = cgbc;
+	wdd = &wdt_data->wdd;
+	wdd->parent = dev;
+
+	wdd->info = &cgbc_wdt_info;
+	wdd->ops = &cgbc_wdt_ops;
+	wdd->max_timeout = CGBC_WDT_MAX_TIMEOUT;
+	wdd->min_timeout = CGBC_WDT_MIN_TIMEOUT;
+
+	watchdog_set_drvdata(wdd, wdt_data);
+	watchdog_set_nowayout(wdd, nowayout);
+
+	wdd->timeout = CGBC_WDT_DEFAULT_TIMEOUT;
+	watchdog_init_timeout(wdd, timeout, dev);
+	cgbc_wdt_set_pretimeout(wdd, pretimeout);
+
+	platform_set_drvdata(pdev, wdt_data);
+	watchdog_stop_on_reboot(wdd);
+	watchdog_stop_on_unregister(wdd);
+
+	return devm_watchdog_register_device(dev, wdd);
+}
+
+static struct platform_driver cgbc_wdt_driver = {
+	.driver		= {
+		.name	= "cgbc-wdt",
+	},
+	.probe		= cgbc_wdt_probe,
+};
+
+module_platform_driver(cgbc_wdt_driver);
+
+MODULE_DESCRIPTION("Congatec Board Controller Watchdog Driver");
+MODULE_AUTHOR("Thomas Richard <thomas.richard@xxxxxxxxxxx>");
+MODULE_LICENSE("GPL");

-- 
2.39.5