Re: [PATCH v3 6/6] watchdog: ts4600: add driver for TS-4600 watchdog

From: Guenter Roeck
Date: Sun May 14 2017 - 10:40:51 EST

On 05/05/2017 12:32 PM, Sebastien Bourdelin wrote:
This watchdog is instantiated in a FPGA and can only be access using a
GPIOs bit-banged bus, called the NBUS by Technologic Systems.
The watchdog is made of only one register, called the feed register.
Writing to this register will re-arm the watchdog for a given time (and
enable it if it was disable). It can be disabled by writing a special
value into it.

Signed-off-by: Sebastien Bourdelin <sebastien.bourdelin@xxxxxxxxxxxxxxxxxxxx>

Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>

When you send v4, please retain unless you make other changes.

Thanks,
Guenter

---
Changes v2 -> v3:
- rebase on master
- remove the timeout table to simplify the logic (suggested by
Guenter Roeck)
- fix the set_timeout function (suggested by Guenter Roeck)
- hardcode the max_hw_heartbeat_ms value based on the ts4600 max
timeout value supported (suggested by Guenter Roeck)
- remove the max_timeout usage and set a default timeout value
(suggested by Guenter Roeck)
- use the devm_watchdog_register_device function instead of
watchdog_register_device (suggested by Guenter Roeck)

Changes v1 -> v2:
- rebase on master
- retrieve the ts_nbus instantiated by the parent node (suggested by
Linus Walleij)
- rename the wdt by watchdog in the device tree and in the
documentation (suggested by Rob Herring)
- add a dependency to the TS_NBUS driver in the Kconfig (suggested by
Guenter Roeck)
- simplify the set_timeout function (suggested by Guenter Roeck)
- use the max_hw_heartbeat_ms callback instead of the max_timeout
callback (suggested by Guenter Roeck)
---
.../devicetree/bindings/watchdog/ts4600-wdt.txt | 16 ++
arch/arm/boot/dts/imx28-ts4600-common.dtsi | 5 +
drivers/watchdog/Kconfig | 11 ++
drivers/watchdog/Makefile | 1 +
drivers/watchdog/ts4600_wdt.c | 185 +++++++++++++++++++++
5 files changed, 218 insertions(+)
create mode 100644 Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt
create mode 100644 drivers/watchdog/ts4600_wdt.c

diff --git a/Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt b/Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt
new file mode 100644
index 000000000000..7de00ceae341
--- /dev/null
+++ b/Documentation/devicetree/bindings/watchdog/ts4600-wdt.txt
@@ -0,0 +1,16 @@
+TS-4600 Technologic Systems Watchdog
+
+Required properties:
+- compatible: must be "technologic,ts4600-wdt"
+- reg: offset to the FPGA's watchdog register
+
+Optional property:
+- timeout-sec: contains the watchdog timeout in seconds.
+
+Example:
+
+watchdog {
+ compatible = "technologic,ts4600-wdt";
+ reg = <0x2a>;
+ timeout-sec = <10>;
+};
diff --git a/arch/arm/boot/dts/imx28-ts4600-common.dtsi b/arch/arm/boot/dts/imx28-ts4600-common.dtsi
index c6282d5479de..092c2eed0fe7 100644
--- a/arch/arm/boot/dts/imx28-ts4600-common.dtsi
+++ b/arch/arm/boot/dts/imx28-ts4600-common.dtsi
@@ -116,6 +116,11 @@
ts-strobe-gpios = <&gpio0 25 GPIO_ACTIVE_HIGH>;
ts-ale-gpios = <&gpio0 26 GPIO_ACTIVE_HIGH>;
ts-rdy-gpios = <&gpio0 21 GPIO_ACTIVE_HIGH>;
+
+ watchdog@2a {
+ compatible = "technologic,ts4600-wdt";
+ reg = <0x2a>;
+ };
};

};
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 52a70ee6014f..408ad7c92cb3 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -520,6 +520,17 @@ config NUC900_WATCHDOG
To compile this driver as a module, choose M here: the
module will be called nuc900_wdt.

+config TS4600_WATCHDOG
+ tristate "TS-4600 Watchdog"
+ depends on TS_NBUS
+ depends on HAS_IOMEM && OF
+ depends on SOC_IMX28 || COMPILE_TEST
+ select WATCHDOG_CORE
+ help
+ Technologic Systems TS-4600 has watchdog timer implemented in
+ an external FPGA. Say Y here if you want to support for the
+ watchdog timer on TS-4600 board.
+
config TS4800_WATCHDOG
tristate "TS-4800 Watchdog"
depends on HAS_IOMEM && OF
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a2126e2a99ae..19553f27061a 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -62,6 +62,7 @@ obj-$(CONFIG_RN5T618_WATCHDOG) += rn5t618_wdt.o
obj-$(CONFIG_COH901327_WATCHDOG) += coh901327_wdt.o
obj-$(CONFIG_STMP3XXX_RTC_WATCHDOG) += stmp3xxx_rtc_wdt.o
obj-$(CONFIG_NUC900_WATCHDOG) += nuc900_wdt.o
+obj-$(CONFIG_TS4600_WATCHDOG) += ts4600_wdt.o
obj-$(CONFIG_TS4800_WATCHDOG) += ts4800_wdt.o
obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
diff --git a/drivers/watchdog/ts4600_wdt.c b/drivers/watchdog/ts4600_wdt.c
new file mode 100644
index 000000000000..ed530dd2f800
--- /dev/null
+++ b/drivers/watchdog/ts4600_wdt.c
@@ -0,0 +1,185 @@
+/*
+ * Watchdog driver for TS-4600 based boards
+ *
+ * Copyright (c) 2016 - Savoir-faire Linux
+ * Author: Sebastien Bourdelin <sebastien.bourdelin@xxxxxxxxxxxxxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * The watchdog on the TS-4600 based boards is in an FPGA and can only be
+ * accessed using a GPIO bit-banged bus called the NBUS by Technologic Systems.
+ * The logic for the watchdog is the same then for the TS-4800 SoM, only the way
+ * to access it change, therefore this driver is heavely based on the ts4800_wdt
+ * driver from Damien Riegel <damien.riegel@xxxxxxxxxxxxxxxxxxxx>.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/ts-nbus.h>
+#include <linux/watchdog.h>
+
+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) ")");
+
+/*
+ * TS-4600 supports the following timeout values:
+ *
+ * value desc
+ * ---------------------
+ * 0 feed for 338ms
+ * 1 feed for 2.706s
+ * 2 feed for 10.824s
+ * 3 disable watchdog
+ */
+#define TS4600_WDT_FEED_2S 0x1
+#define TS4600_WDT_FEED_10S 0x2
+#define TS4600_WDT_DISABLE 0x3
+
+struct ts4600_wdt {
+ struct watchdog_device wdd;
+ struct ts_nbus *ts_nbus;
+ u32 feed_offset;
+ u32 feed_val;
+};
+
+static void ts4600_write_feed(struct ts4600_wdt *wdt, u32 val)
+{
+ ts_nbus_write(wdt->ts_nbus, wdt->feed_offset, val);
+}
+
+static int ts4600_wdt_start(struct watchdog_device *wdd)
+{
+ struct ts4600_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ ts4600_write_feed(wdt, wdt->feed_val);
+
+ return 0;
+}
+
+static int ts4600_wdt_stop(struct watchdog_device *wdd)
+{
+ struct ts4600_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ ts4600_write_feed(wdt, TS4600_WDT_DISABLE);
+ return 0;
+}
+
+static int ts4600_wdt_set_timeout(struct watchdog_device *wdd,
+ unsigned int timeout)
+{
+ struct ts4600_wdt *wdt = watchdog_get_drvdata(wdd);
+
+ if (timeout <= 2) {
+ wdd->timeout = 2;
+ wdt->feed_val = TS4600_WDT_FEED_2S;
+ } else {
+ wdd->timeout = timeout < 10 ? 10 : timeout;
+ wdt->feed_val = TS4600_WDT_FEED_10S;
+ }
+
+ return 0;
+}
+
+static const struct watchdog_ops ts4600_wdt_ops = {
+ .owner = THIS_MODULE,
+ .start = ts4600_wdt_start,
+ .stop = ts4600_wdt_stop,
+ .set_timeout = ts4600_wdt_set_timeout,
+};
+
+static const struct watchdog_info ts4600_wdt_info = {
+ .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+ .identity = "TS-4600 Watchdog",
+};
+
+static int ts4600_wdt_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ struct ts_nbus *ts_nbus;
+ struct watchdog_device *wdd;
+ struct ts4600_wdt *wdt;
+ u32 reg;
+ int ret;
+
+ ret = of_property_read_u32(np, "reg", &reg);
+ if (ret < 0) {
+ dev_err(&pdev->dev, "missing reg property\n");
+ return ret;
+ }
+
+ /* allocate memory for watchdog struct */
+ wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+ if (!wdt)
+ return -ENOMEM;
+
+ /* set offset to know where to write */
+ wdt->feed_offset = reg;
+
+ /* keep a pointer to the ts_nbus instanciated by the parent node */
+ ts_nbus = dev_get_drvdata(dev->parent);
+ if (!ts_nbus) {
+ dev_err(dev, "missing ts-nbus compatible parent node\n");
+ return PTR_ERR(ts_nbus);
+ }
+ wdt->ts_nbus = ts_nbus;
+
+ /* Initialize struct watchdog_device */
+ wdd = &wdt->wdd;
+ wdd->parent = dev;
+ wdd->info = &ts4600_wdt_info;
+ wdd->ops = &ts4600_wdt_ops;
+ wdd->min_timeout = 2;
+ wdd->max_hw_heartbeat_ms = 10824;
+ wdd->timeout = 30;
+
+ watchdog_set_drvdata(wdd, wdt);
+ watchdog_set_nowayout(wdd, nowayout);
+ watchdog_init_timeout(wdd, 0, dev);
+
+ ts4600_wdt_set_timeout(wdd, wdd->timeout);
+
+ /*
+ * The feed register is write-only, so it is not possible to determine
+ * watchdog's state. Disable it to be in a known state.
+ */
+ ts4600_wdt_stop(wdd);
+
+ ret = devm_watchdog_register_device(&pdev->dev, &wdt->wdd);
+ if (ret) {
+ dev_err(dev, "failed to register watchdog device\n");
+ return ret;
+ }
+
+ dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n",
+ wdd->timeout, nowayout);
+
+ return 0;
+}
+
+static const struct of_device_id ts4600_wdt_of_match[] = {
+ { .compatible = "technologic,ts4600-wdt", },
+ { },
+};
+MODULE_DEVICE_TABLE(of, ts4600_wdt_of_match);
+
+static struct platform_driver ts4600_wdt_driver = {
+ .probe = ts4600_wdt_probe,
+ .driver = {
+ .name = "ts4600_wdt",
+ .of_match_table = ts4600_wdt_of_match,
+ },
+};
+
+module_platform_driver(ts4600_wdt_driver);
+
+MODULE_AUTHOR("Sebastien Bourdelin <sebastien.bourdelin@xxxxxxxxxxxxxxxxxxxx>");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:ts4600_wdt");