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Diffstat (limited to '')
| -rw-r--r-- | drivers/watchdog/ts4800_wdt.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/drivers/watchdog/ts4800_wdt.c b/drivers/watchdog/ts4800_wdt.c new file mode 100644 index 000000000..0ea554c7c --- /dev/null +++ b/drivers/watchdog/ts4800_wdt.c @@ -0,0 +1,206 @@ +/* + * 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 *dev = &pdev->dev; + struct device_node *np = 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(dev, "no syscon property\n"); + return -ENODEV; + } + + ret = of_property_read_u32_index(np, "syscon", 1, ®); + if (ret < 0) { + dev_err(dev, "no offset in syscon\n"); + of_node_put(syscon_np); + return ret; + } + + /* allocate memory for watchdog struct */ + wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL); + if (!wdt) { + of_node_put(syscon_np); + return -ENOMEM; + } + + /* set regmap and offset to know where to write */ + wdt->feed_offset = reg; + wdt->regmap = syscon_node_to_regmap(syscon_np); + of_node_put(syscon_np); + if (IS_ERR(wdt->regmap)) { + dev_err(dev, "cannot get parent's regmap\n"); + return PTR_ERR(wdt->regmap); + } + + /* Initialize struct watchdog_device */ + wdd = &wdt->wdd; + wdd->parent = 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, 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 = devm_watchdog_register_device(dev, wdd); + if (ret) + return ret; + + platform_set_drvdata(pdev, wdt); + + dev_info(dev, "initialized (timeout = %d sec, nowayout = %d)\n", + wdd->timeout, nowayout); + + 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, + .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"); |