Re: [PATCH v7 3/6] watchdog: ts4800: add driver for TS-4800 watchdog

Rob Herring
2015-11-30T19:01:54Z

On Mon, Nov 30, 2015 at 10:59:48AM -0500, Damien Riegel wrote:
> This watchdog is instantiated in a FPGA that is memory mapped. It 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.
>
> It is part of a syscon block, and the watchdog register offset in this
> block varies from board to board. This offset is passed in the syscon
> property after the phandle to the syscon node.
>
> Signed-off-by: Damien Riegel <damien.riegel@savoirfairelinux.com>
> ---
> .../devicetree/bindings/watchdog/ts4800-wdt.txt | 25 +++

For the binding:

Acked-by: Rob Herring <robh@kernel.org>

> drivers/watchdog/Kconfig | 10 +
> drivers/watchdog/Makefile | 1 +
> drivers/watchdog/ts4800_wdt.c | 215 +++++++++++++++++++++
> 4 files changed, 251 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/watchdog/ts4800-wdt.txt
> create mode 100644 drivers/watchdog/ts4800_wdt.c
>
> diff --git a/Documentation/devicetree/bindings/watchdog/ts4800-wdt.txt b/Documentation/devicetree/bindings/watchdog/ts4800-wdt.txt
> new file mode 100644
> index 0000000..8f6caad
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/watchdog/ts4800-wdt.txt
> @@ -0,0 +1,25 @@
> +Technologic Systems Watchdog
> +
> +Required properties:
> +- compatible: must be "technologic,ts4800-wdt"
> +- syscon: phandle / integer array that points to the syscon node which
> + describes the FPGA's syscon registers.
> + - phandle to FPGA's syscon
> + - offset to the watchdog register
> +
> +Optional property:
> +- timeout-sec: contains the watchdog timeout in seconds.
> +
> +Example:
> +
> +syscon: syscon@b0010000 {
> + compatible = "syscon", "simple-mfd";
> + reg = <0xb0010000 0x3d>;
> + reg-io-width = <2>;
> +
> + wdt@e {
> + compatible = "technologic,ts4800-wdt";
> + syscon = <&syscon 0xe>;
> + timeout-sec = <10>;
> + };
> +}
> diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> index 79e1aa1..bb624d2 100644
> --- a/drivers/watchdog/Kconfig
> +++ b/drivers/watchdog/Kconfig
> @@ -426,6 +426,16 @@ config NUC900_WATCHDOG
> To compile this driver as a module, choose M here: the
> module will be called nuc900_wdt.
>
> +config TS4800_WATCHDOG
> + tristate "TS-4800 Watchdog"
> + depends on HAS_IOMEM && OF
> + select WATCHDOG_CORE
> + select MFD_SYSCON
> + help
> + Technologic Systems TS-4800 has watchdog timer implemented in
> + an external FPGA. Say Y here if you want to support for the
> + watchdog timer on TS-4800 board.
> +
> config TS72XX_WATCHDOG
> tristate "TS-72XX SBC Watchdog"
> depends on MACH_TS72XX
> diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
> index 0c616e3..3863ce0 100644
> --- a/drivers/watchdog/Makefile
> +++ b/drivers/watchdog/Makefile
> @@ -53,6 +53,7 @@ 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-$(CONFIG_TS4800_WATCHDOG) += ts4800_wdt.o
> obj-$(CONFIG_TS72XX_WATCHDOG) += ts72xx_wdt.o
> obj-$(CONFIG_IMX2_WDT) += imx2_wdt.o
> obj-$(CONFIG_UX500_WATCHDOG) += ux500_wdt.o
> diff --git a/drivers/watchdog/ts4800_wdt.c b/drivers/watchdog/ts4800_wdt.c
> new file mode 100644
> index 0000000..2b8de86
> --- /dev/null
> +++ b/drivers/watchdog/ts4800_wdt.c
> @@ -0,0 +1,215 @@
> +/*
> + * Watchdog driver for TS-4800 based boards
> + *
> + * Copyright (c) 2015 - Savoir-faire Linux
> + *
> + * 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.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.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) ")");
> +
> +/* possible feed values */
> +#define TS4800_WDT_FEED_2S 0x1
> +#define TS4800_WDT_FEED_10S 0x2
> +#define TS4800_WDT_DISABLE 0x3
> +
> +struct ts4800_wdt {
> + struct watchdog_device wdd;
> + struct regmap *regmap;
> + u32 feed_offset;
> + u32 feed_val;
> +};
> +
> +/*
> + * TS-4800 supports the following timeout values:
> + *
> + * value desc
> + * ---------------------
> + * 0 feed for 338ms
> + * 1 feed for 2.706s
> + * 2 feed for 10.824s
> + * 3 disable watchdog
> + *
> + * Keep the regmap/timeout map ordered by timeout
> + */
> +static const struct {
> + const int timeout;
> + const int regval;
> +} ts4800_wdt_map[] = {
> + { 2, TS4800_WDT_FEED_2S },
> + { 10, TS4800_WDT_FEED_10S },
> +};
> +
> +#define MAX_TIMEOUT_INDEX (ARRAY_SIZE(ts4800_wdt_map) - 1)
> +
> +static void ts4800_write_feed(struct ts4800_wdt *wdt, u32 val)
> +{
> + regmap_write(wdt->regmap, wdt->feed_offset, val);
> +}
> +
> +static int ts4800_wdt_start(struct watchdog_device *wdd)
> +{
> + struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> + ts4800_write_feed(wdt, wdt->feed_val);
> + return 0;
> +}
> +
> +static int ts4800_wdt_stop(struct watchdog_device *wdd)
> +{
> + struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
> +
> + ts4800_write_feed(wdt, TS4800_WDT_DISABLE);
> + return 0;
> +}
> +
> +static int ts4800_wdt_set_timeout(struct watchdog_device *wdd,
> + unsigned int timeout)
> +{
> + struct ts4800_wdt *wdt = watchdog_get_drvdata(wdd);
> + int i;
> +
> + for (i = 0; i < MAX_TIMEOUT_INDEX; i++) {
> + if (ts4800_wdt_map[i].timeout >= timeout)
> + break;
> + }
> +
> + wdd->timeout = ts4800_wdt_map[i].timeout;
> + wdt->feed_val = ts4800_wdt_map[i].regval;
> +
> + return 0;
> +}
> +
> +static const struct watchdog_ops ts4800_wdt_ops = {
> + .owner = THIS_MODULE,
> + .start = ts4800_wdt_start,
> + .stop = ts4800_wdt_stop,
> + .set_timeout = ts4800_wdt_set_timeout,
> +};
> +
> +static const struct watchdog_info ts4800_wdt_info = {
> + .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
> + .identity = "TS-4800 Watchdog",
> +};
> +
> +static int ts4800_wdt_probe(struct platform_device *pdev)
> +{
> + struct device_node *np = pdev->dev.of_node;
> + struct device_node *syscon_np;
> + struct watchdog_device *wdd;
> + struct ts4800_wdt *wdt;
> + u32 reg;
> + int ret;
> +
> + syscon_np = of_parse_phandle(np, "syscon", 0);
> + if (!syscon_np) {
> + dev_err(&pdev->dev, "no syscon property\n");
> + return -ENODEV;
> + }
> +
> + ret = of_property_read_u32_index(np, "syscon", 1, &reg);
> + if (ret < 0) {
> + dev_err(&pdev->dev, "no offset in syscon\n");
> + return ret;
> + }
> +
> + /* allocate memory for watchdog struct */
> + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> + if (!wdt)
> + return -ENOMEM;
> +
> + /* set regmap and offset to know where to write */
> + wdt->feed_offset = reg;
> + wdt->regmap = syscon_node_to_regmap(syscon_np);
> + if (IS_ERR(wdt->regmap)) {
> + dev_err(&pdev->dev, "cannot get parent's regmap\n");
> + return PTR_ERR(wdt->regmap);
> + }
> +
> + /* Initialize struct watchdog_device */
> + wdd = &wdt->wdd;
> + wdd->parent = &pdev->dev;
> + wdd->info = &ts4800_wdt_info;
> + wdd->ops = &ts4800_wdt_ops;
> + wdd->min_timeout = ts4800_wdt_map[0].timeout;
> + wdd->max_timeout = ts4800_wdt_map[MAX_TIMEOUT_INDEX].timeout;
> +
> + watchdog_set_drvdata(wdd, wdt);
> + watchdog_set_nowayout(wdd, nowayout);
> + watchdog_init_timeout(wdd, 0, &pdev->dev);
> +
> + /*
> + * As this watchdog supports only a few values, ts4800_wdt_set_timeout
> + * must be called to initialize timeout and feed_val with valid values.
> + * Default to maximum timeout if none, or an invalid one, is provided in
> + * device tree.
> + */
> + if (!wdd->timeout)
> + wdd->timeout = wdd->max_timeout;
> + ts4800_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.
> + */
> + ts4800_wdt_stop(wdd);
> +
> + ret = watchdog_register_device(wdd);
> + if (ret) {
> + dev_err(&pdev->dev,
> + "failed to register watchdog device\n");
> + return ret;
> + }
> +
> + platform_set_drvdata(pdev, wdt);
> +
> + dev_info(&pdev->dev,
> + "initialized (timeout = %d sec, nowayout = %d)\n",
> + wdd->timeout, nowayout);
> +
> + return 0;
> +}
> +
> +static int ts4800_wdt_remove(struct platform_device *pdev)
> +{
> + struct ts4800_wdt *wdt = platform_get_drvdata(pdev);
> +
> + watchdog_unregister_device(&wdt->wdd);
> +
> + return 0;
> +}
> +
> +static const struct of_device_id ts4800_wdt_of_match[] = {
> + { .compatible = "technologic,ts4800-wdt", },
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, ts4800_wdt_of_match);
> +
> +static struct platform_driver ts4800_wdt_driver = {
> + .probe = ts4800_wdt_probe,
> + .remove = ts4800_wdt_remove,
> + .driver = {
> + .name = "ts4800_wdt",
> + .of_match_table = ts4800_wdt_of_match,
> + },
> +};
> +
> +module_platform_driver(ts4800_wdt_driver);
> +
> +MODULE_AUTHOR("Damien Riegel <damien.riegel@savoirfairelinux.com>");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:ts4800_wdt");
> --
> 2.5.0
>