diff options
Diffstat (limited to 'drivers/watchdog/exar_wdt.c')
| -rw-r--r-- | drivers/watchdog/exar_wdt.c | 429 |
1 files changed, 429 insertions, 0 deletions
diff --git a/drivers/watchdog/exar_wdt.c b/drivers/watchdog/exar_wdt.c new file mode 100644 index 000000000..7c61ff343 --- /dev/null +++ b/drivers/watchdog/exar_wdt.c @@ -0,0 +1,429 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * exar_wdt.c - Driver for the watchdog present in some + * Exar/MaxLinear UART chips like the XR28V38x. + * + * (c) Copyright 2022 D. Müller <d.mueller@elsoft.ch>. + * + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/io.h> +#include <linux/list.h> +#include <linux/module.h> +#include <linux/platform_device.h> +#include <linux/slab.h> +#include <linux/watchdog.h> + +#define DRV_NAME "exar_wdt" + +static const unsigned short sio_config_ports[] = { 0x2e, 0x4e }; +static const unsigned char sio_enter_keys[] = { 0x67, 0x77, 0x87, 0xA0 }; +#define EXAR_EXIT_KEY 0xAA + +#define EXAR_LDN 0x07 +#define EXAR_DID 0x20 +#define EXAR_VID 0x23 +#define EXAR_WDT 0x26 +#define EXAR_ACT 0x30 +#define EXAR_RTBASE 0x60 + +#define EXAR_WDT_LDEV 0x08 + +#define EXAR_VEN_ID 0x13A8 +#define EXAR_DEV_382 0x0382 +#define EXAR_DEV_384 0x0384 + +/* WDT runtime registers */ +#define WDT_CTRL 0x00 +#define WDT_VAL 0x01 + +#define WDT_UNITS_10MS 0x0 /* the 10 millisec unit of the HW is not used */ +#define WDT_UNITS_SEC 0x2 +#define WDT_UNITS_MIN 0x4 + +/* default WDT control for WDTOUT signal activ / rearm by read */ +#define EXAR_WDT_DEF_CONF 0 + +struct wdt_pdev_node { + struct list_head list; + struct platform_device *pdev; + const char name[16]; +}; + +struct wdt_priv { + /* the lock for WDT io operations */ + spinlock_t io_lock; + struct resource wdt_res; + struct watchdog_device wdt_dev; + unsigned short did; + unsigned short config_port; + unsigned char enter_key; + unsigned char unit; + unsigned char timeout; +}; + +#define WATCHDOG_TIMEOUT 60 + +static int timeout = WATCHDOG_TIMEOUT; +module_param(timeout, int, 0); +MODULE_PARM_DESC(timeout, + "Watchdog timeout in seconds. 1<=timeout<=15300, default=" + __MODULE_STRING(WATCHDOG_TIMEOUT) "."); + +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 exar_sio_enter(const unsigned short config_port, + const unsigned char key) +{ + if (!request_muxed_region(config_port, 2, DRV_NAME)) + return -EBUSY; + + /* write the ENTER-KEY twice */ + outb(key, config_port); + outb(key, config_port); + + return 0; +} + +static void exar_sio_exit(const unsigned short config_port) +{ + outb(EXAR_EXIT_KEY, config_port); + release_region(config_port, 2); +} + +static unsigned char exar_sio_read(const unsigned short config_port, + const unsigned char reg) +{ + outb(reg, config_port); + return inb(config_port + 1); +} + +static void exar_sio_write(const unsigned short config_port, + const unsigned char reg, const unsigned char val) +{ + outb(reg, config_port); + outb(val, config_port + 1); +} + +static unsigned short exar_sio_read16(const unsigned short config_port, + const unsigned char reg) +{ + unsigned char msb, lsb; + + msb = exar_sio_read(config_port, reg); + lsb = exar_sio_read(config_port, reg + 1); + + return (msb << 8) | lsb; +} + +static void exar_sio_select_wdt(const unsigned short config_port) +{ + exar_sio_write(config_port, EXAR_LDN, EXAR_WDT_LDEV); +} + +static void exar_wdt_arm(const struct wdt_priv *priv) +{ + unsigned short rt_base = priv->wdt_res.start; + + /* write timeout value twice to arm watchdog */ + outb(priv->timeout, rt_base + WDT_VAL); + outb(priv->timeout, rt_base + WDT_VAL); +} + +static void exar_wdt_disarm(const struct wdt_priv *priv) +{ + unsigned short rt_base = priv->wdt_res.start; + + /* + * use two accesses with different values to make sure + * that a combination of a previous single access and + * the ones below with the same value are not falsely + * interpreted as "arm watchdog" + */ + outb(0xFF, rt_base + WDT_VAL); + outb(0, rt_base + WDT_VAL); +} + +static int exar_wdt_start(struct watchdog_device *wdog) +{ + struct wdt_priv *priv = watchdog_get_drvdata(wdog); + unsigned short rt_base = priv->wdt_res.start; + + spin_lock(&priv->io_lock); + + exar_wdt_disarm(priv); + outb(priv->unit, rt_base + WDT_CTRL); + exar_wdt_arm(priv); + + spin_unlock(&priv->io_lock); + return 0; +} + +static int exar_wdt_stop(struct watchdog_device *wdog) +{ + struct wdt_priv *priv = watchdog_get_drvdata(wdog); + + spin_lock(&priv->io_lock); + + exar_wdt_disarm(priv); + + spin_unlock(&priv->io_lock); + return 0; +} + +static int exar_wdt_keepalive(struct watchdog_device *wdog) +{ + struct wdt_priv *priv = watchdog_get_drvdata(wdog); + unsigned short rt_base = priv->wdt_res.start; + + spin_lock(&priv->io_lock); + + /* reading the WDT_VAL reg will feed the watchdog */ + inb(rt_base + WDT_VAL); + + spin_unlock(&priv->io_lock); + return 0; +} + +static int exar_wdt_set_timeout(struct watchdog_device *wdog, unsigned int t) +{ + struct wdt_priv *priv = watchdog_get_drvdata(wdog); + bool unit_min = false; + + /* + * if new timeout is bigger then 255 seconds, change the + * unit to minutes and round the timeout up to the next whole minute + */ + if (t > 255) { + unit_min = true; + t = DIV_ROUND_UP(t, 60); + } + + /* save for later use in exar_wdt_start() */ + priv->unit = unit_min ? WDT_UNITS_MIN : WDT_UNITS_SEC; + priv->timeout = t; + + wdog->timeout = unit_min ? t * 60 : t; + + if (watchdog_hw_running(wdog)) + exar_wdt_start(wdog); + + return 0; +} + +static const struct watchdog_info exar_wdt_info = { + .options = WDIOF_KEEPALIVEPING | + WDIOF_SETTIMEOUT | + WDIOF_MAGICCLOSE, + .identity = "Exar/MaxLinear XR28V38x Watchdog", +}; + +static const struct watchdog_ops exar_wdt_ops = { + .owner = THIS_MODULE, + .start = exar_wdt_start, + .stop = exar_wdt_stop, + .ping = exar_wdt_keepalive, + .set_timeout = exar_wdt_set_timeout, +}; + +static int exar_wdt_config(struct watchdog_device *wdog, + const unsigned char conf) +{ + struct wdt_priv *priv = watchdog_get_drvdata(wdog); + int ret; + + ret = exar_sio_enter(priv->config_port, priv->enter_key); + if (ret) + return ret; + + exar_sio_select_wdt(priv->config_port); + exar_sio_write(priv->config_port, EXAR_WDT, conf); + + exar_sio_exit(priv->config_port); + + return 0; +} + +static int __init exar_wdt_probe(struct platform_device *pdev) +{ + struct device *dev = &pdev->dev; + struct wdt_priv *priv = dev->platform_data; + struct watchdog_device *wdt_dev = &priv->wdt_dev; + struct resource *res; + int ret; + + res = platform_get_resource(pdev, IORESOURCE_IO, 0); + if (!res) + return -ENXIO; + + spin_lock_init(&priv->io_lock); + + wdt_dev->info = &exar_wdt_info; + wdt_dev->ops = &exar_wdt_ops; + wdt_dev->min_timeout = 1; + wdt_dev->max_timeout = 255 * 60; + + watchdog_init_timeout(wdt_dev, timeout, NULL); + watchdog_set_nowayout(wdt_dev, nowayout); + watchdog_stop_on_reboot(wdt_dev); + watchdog_stop_on_unregister(wdt_dev); + watchdog_set_drvdata(wdt_dev, priv); + + ret = exar_wdt_config(wdt_dev, EXAR_WDT_DEF_CONF); + if (ret) + return ret; + + exar_wdt_set_timeout(wdt_dev, timeout); + /* Make sure that the watchdog is not running */ + exar_wdt_stop(wdt_dev); + + ret = devm_watchdog_register_device(dev, wdt_dev); + if (ret) + return ret; + + dev_info(dev, "XR28V%X WDT initialized. timeout=%d sec (nowayout=%d)\n", + priv->did, timeout, nowayout); + + return 0; +} + +static unsigned short __init exar_detect(const unsigned short config_port, + const unsigned char key, + unsigned short *rt_base) +{ + int ret; + unsigned short base = 0; + unsigned short vid, did; + + ret = exar_sio_enter(config_port, key); + if (ret) + return 0; + + vid = exar_sio_read16(config_port, EXAR_VID); + did = exar_sio_read16(config_port, EXAR_DID); + + /* check for the vendor and device IDs we currently know about */ + if (vid == EXAR_VEN_ID && + (did == EXAR_DEV_382 || + did == EXAR_DEV_384)) { + exar_sio_select_wdt(config_port); + /* is device active? */ + if (exar_sio_read(config_port, EXAR_ACT) == 0x01) + base = exar_sio_read16(config_port, EXAR_RTBASE); + } + + exar_sio_exit(config_port); + + if (base) { + pr_debug("Found a XR28V%X WDT (conf: 0x%x / rt: 0x%04x)\n", + did, config_port, base); + *rt_base = base; + return did; + } + + return 0; +} + +static struct platform_driver exar_wdt_driver = { + .driver = { + .name = DRV_NAME, + }, +}; + +static LIST_HEAD(pdev_list); + +static int __init exar_wdt_register(struct wdt_priv *priv, const int idx) +{ + struct wdt_pdev_node *n; + + n = kzalloc(sizeof(*n), GFP_KERNEL); + if (!n) + return -ENOMEM; + + INIT_LIST_HEAD(&n->list); + + scnprintf((char *)n->name, sizeof(n->name), DRV_NAME ".%d", idx); + priv->wdt_res.name = n->name; + + n->pdev = platform_device_register_resndata(NULL, DRV_NAME, idx, + &priv->wdt_res, 1, + priv, sizeof(*priv)); + if (IS_ERR(n->pdev)) { + int err = PTR_ERR(n->pdev); + + kfree(n); + return err; + } + + list_add_tail(&n->list, &pdev_list); + + return 0; +} + +static void exar_wdt_unregister(void) +{ + struct wdt_pdev_node *n, *t; + + list_for_each_entry_safe(n, t, &pdev_list, list) { + platform_device_unregister(n->pdev); + list_del(&n->list); + kfree(n); + } +} + +static int __init exar_wdt_init(void) +{ + int ret, i, j, idx = 0; + + /* search for active Exar watchdogs on all possible locations */ + for (i = 0; i < ARRAY_SIZE(sio_config_ports); i++) { + for (j = 0; j < ARRAY_SIZE(sio_enter_keys); j++) { + unsigned short did, rt_base = 0; + + did = exar_detect(sio_config_ports[i], + sio_enter_keys[j], + &rt_base); + + if (did) { + struct wdt_priv priv = { + .wdt_res = DEFINE_RES_IO(rt_base, 2), + .did = did, + .config_port = sio_config_ports[i], + .enter_key = sio_enter_keys[j], + }; + + ret = exar_wdt_register(&priv, idx); + if (!ret) + idx++; + } + } + } + + if (!idx) + return -ENODEV; + + ret = platform_driver_probe(&exar_wdt_driver, exar_wdt_probe); + if (ret) + exar_wdt_unregister(); + + return ret; +} + +static void __exit exar_wdt_exit(void) +{ + exar_wdt_unregister(); + platform_driver_unregister(&exar_wdt_driver); +} + +module_init(exar_wdt_init); +module_exit(exar_wdt_exit); + +MODULE_AUTHOR("David Müller <d.mueller@elsoft.ch>"); +MODULE_DESCRIPTION("Exar/MaxLinear Watchdog Driver"); +MODULE_LICENSE("GPL"); |