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Subject[PATCH v9 05/13] watchdog: add support for sl28cpld watchdog
Date
Add support for the watchdog of the sl28cpld board management
controller. This is part of a multi-function device driver.

Signed-off-by: Michael Walle <michael@walle.cc>
Acked-by: Guenter Roeck <linux@roeck-us.net>
---
Changes since v8:
- none

Changes since v7:
- added "depends on MFD_SL28CPLD || COMPILE_TEST"

Changes since v6:
- none

Changes since v5:
- none

Changes since v4:
- update copyright year
- remove #include <linux/of_device.h>, suggested by Andy.
- slightly reworked the error code handling (only style), suggested by
Andy.
- Don't use "if (ret < 0)", but only "if (ret)", suggested by Andy.
- remove comma in terminator line of the compatible strings list
- don't use KBUID_MODNAME
- remove the platform device table

Changes since v3:
- see cover letter

drivers/watchdog/Kconfig | 11 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/sl28cpld_wdt.c | 229 ++++++++++++++++++++++++++++++++
3 files changed, 241 insertions(+)
create mode 100644 drivers/watchdog/sl28cpld_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index e4dd49895567..ba3108ca757d 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -340,6 +340,17 @@ config MLX_WDT
To compile this driver as a module, choose M here: the
module will be called mlx-wdt.

+config SL28CPLD_WATCHDOG
+ tristate "Kontron sl28cpld Watchdog"
+ depends on MFD_SL28CPLD || COMPILE_TEST
+ select WATCHDOG_CORE
+ help
+ Say Y here to include support for the watchdog timer
+ on the Kontron sl28 CPLD.
+
+ To compile this driver as a module, choose M here: the
+ module will be called sl28cpld_wdt.
+
# ALPHA Architecture

# ARM Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 97bed1d3d97c..aa6e41126901 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -225,3 +225,4 @@ obj-$(CONFIG_MENF21BMC_WATCHDOG) += menf21bmc_wdt.o
obj-$(CONFIG_MENZ069_WATCHDOG) += menz69_wdt.o
obj-$(CONFIG_RAVE_SP_WATCHDOG) += rave-sp-wdt.o
obj-$(CONFIG_STPMIC1_WATCHDOG) += stpmic1_wdt.o
+obj-$(CONFIG_SL28CPLD_WATCHDOG) += sl28cpld_wdt.o
diff --git a/drivers/watchdog/sl28cpld_wdt.c b/drivers/watchdog/sl28cpld_wdt.c
new file mode 100644
index 000000000000..a45047d8d9ab
--- /dev/null
+++ b/drivers/watchdog/sl28cpld_wdt.c
@@ -0,0 +1,229 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sl28cpld watchdog driver
+ *
+ * Copyright 2020 Kontron Europe GmbH
+ */
+
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/regmap.h>
+#include <linux/watchdog.h>
+
+/*
+ * Watchdog timer block registers.
+ */
+#define WDT_CTRL 0x00
+#define WDT_CTRL_EN BIT(0)
+#define WDT_CTRL_LOCK BIT(2)
+#define WDT_CTRL_ASSERT_SYS_RESET BIT(6)
+#define WDT_CTRL_ASSERT_WDT_TIMEOUT BIT(7)
+#define WDT_TIMEOUT 0x01
+#define WDT_KICK 0x02
+#define WDT_KICK_VALUE 0x6b
+#define WDT_COUNT 0x03
+
+#define WDT_DEFAULT_TIMEOUT 10
+
+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) ")");
+
+static int timeout;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Initial watchdog timeout in seconds");
+
+struct sl28cpld_wdt {
+ struct watchdog_device wdd;
+ struct regmap *regmap;
+ u32 offset;
+ bool assert_wdt_timeout;
+};
+
+static int sl28cpld_wdt_ping(struct watchdog_device *wdd)
+{
+ struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ return regmap_write(wdt->regmap, wdt->offset + WDT_KICK,
+ WDT_KICK_VALUE);
+}
+
+static int sl28cpld_wdt_start(struct watchdog_device *wdd)
+{
+ struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
+ unsigned int val;
+
+ val = WDT_CTRL_EN | WDT_CTRL_ASSERT_SYS_RESET;
+ if (wdt->assert_wdt_timeout)
+ val |= WDT_CTRL_ASSERT_WDT_TIMEOUT;
+ if (nowayout)
+ val |= WDT_CTRL_LOCK;
+
+ return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
+ val, val);
+}
+
+static int sl28cpld_wdt_stop(struct watchdog_device *wdd)
+{
+ struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ return regmap_update_bits(wdt->regmap, wdt->offset + WDT_CTRL,
+ WDT_CTRL_EN, 0);
+}
+
+static unsigned int sl28cpld_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+ struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
+ unsigned int val;
+ int ret;
+
+ ret = regmap_read(wdt->regmap, wdt->offset + WDT_COUNT, &val);
+ if (ret)
+ return 0;
+
+ return val;
+}
+
+static int sl28cpld_wdt_set_timeout(struct watchdog_device *wdd,
+ unsigned int timeout)
+{
+ struct sl28cpld_wdt *wdt = watchdog_get_drvdata(wdd);
+ int ret;
+
+ ret = regmap_write(wdt->regmap, wdt->offset + WDT_TIMEOUT, timeout);
+ if (ret)
+ return ret;
+
+ wdd->timeout = timeout;
+
+ return 0;
+}
+
+static const struct watchdog_info sl28cpld_wdt_info = {
+ .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING,
+ .identity = "sl28cpld watchdog",
+};
+
+static struct watchdog_ops sl28cpld_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = sl28cpld_wdt_start,
+ .stop = sl28cpld_wdt_stop,
+ .ping = sl28cpld_wdt_ping,
+ .set_timeout = sl28cpld_wdt_set_timeout,
+ .get_timeleft = sl28cpld_wdt_get_timeleft,
+};
+
+static int sl28cpld_wdt_probe(struct platform_device *pdev)
+{
+ struct watchdog_device *wdd;
+ struct sl28cpld_wdt *wdt;
+ unsigned int status;
+ unsigned int val;
+ int ret;
+
+ if (!pdev->dev.parent)
+ return -ENODEV;
+
+ wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+ if (!wdt)
+ return -ENOMEM;
+
+ wdt->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+ if (!wdt->regmap)
+ return -ENODEV;
+
+ ret = device_property_read_u32(&pdev->dev, "reg", &wdt->offset);
+ if (ret)
+ return -EINVAL;
+
+ wdt->assert_wdt_timeout = device_property_read_bool(&pdev->dev,
+ "kontron,assert-wdt-timeout-pin");
+
+ /* initialize struct watchdog_device */
+ wdd = &wdt->wdd;
+ wdd->parent = &pdev->dev;
+ wdd->info = &sl28cpld_wdt_info;
+ wdd->ops = &sl28cpld_wdt_ops;
+ wdd->min_timeout = 1;
+ wdd->max_timeout = 255;
+
+ watchdog_set_drvdata(wdd, wdt);
+ watchdog_stop_on_reboot(wdd);
+
+ /*
+ * Read the status early, in case of an error, we haven't modified the
+ * hardware.
+ */
+ ret = regmap_read(wdt->regmap, wdt->offset + WDT_CTRL, &status);
+ if (ret)
+ return ret;
+
+ /*
+ * Initial timeout value, may be overwritten by device tree or module
+ * parmeter in watchdog_init_timeout().
+ *
+ * Reading a zero here means that either the hardware has a default
+ * value of zero (which is very unlikely and definitely a hardware
+ * bug) or the bootloader set it to zero. In any case, we handle
+ * this case gracefully and set out own timeout.
+ */
+ ret = regmap_read(wdt->regmap, wdt->offset + WDT_TIMEOUT, &val);
+ if (ret)
+ return ret;
+
+ if (val)
+ wdd->timeout = val;
+ else
+ wdd->timeout = WDT_DEFAULT_TIMEOUT;
+
+ watchdog_init_timeout(wdd, timeout, &pdev->dev);
+ sl28cpld_wdt_set_timeout(wdd, wdd->timeout);
+
+ /* if the watchdog is locked, we set nowayout */
+ if (status & WDT_CTRL_LOCK)
+ nowayout = true;
+ watchdog_set_nowayout(wdd, nowayout);
+
+ /*
+ * If watchdog is already running, keep it enabled, but make
+ * sure its mode is set correctly.
+ */
+ if (status & WDT_CTRL_EN) {
+ sl28cpld_wdt_start(wdd);
+ set_bit(WDOG_HW_RUNNING, &wdd->status);
+ }
+
+ ret = devm_watchdog_register_device(&pdev->dev, wdd);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "failed to register watchdog device\n");
+ return ret;
+ }
+
+ dev_info(&pdev->dev, "initial timeout %d sec%s\n",
+ wdd->timeout, nowayout ? ", nowayout" : "");
+
+ return 0;
+}
+
+static const struct of_device_id sl28cpld_wdt_of_match[] = {
+ { .compatible = "kontron,sl28cpld-wdt" },
+ {}
+};
+MODULE_DEVICE_TABLE(of, sl28cpld_wdt_of_match);
+
+static struct platform_driver sl28cpld_wdt_driver = {
+ .probe = sl28cpld_wdt_probe,
+ .driver = {
+ .name = "sl28cpld-wdt",
+ .of_match_table = sl28cpld_wdt_of_match,
+ },
+};
+module_platform_driver(sl28cpld_wdt_driver);
+
+MODULE_DESCRIPTION("sl28cpld Watchdog Driver");
+MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
+MODULE_LICENSE("GPL");
--
2.20.1
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