--- /dev/null
+// 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)) {
+ kfree(n);
+ return PTR_ERR(n->pdev);
+ }
+
+ 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");
projects / platform / kernel / linux-rpi.git / commitdiff