1 files changed, 356 insertions, 0 deletions
diff --git a/drivers/watchdog/rti_wdt.c b/drivers/watchdog/rti_wdt.c
new file mode 100644
index 000000000..ea617c0f9
--- /dev/null
+++ b/drivers/watchdog/rti_wdt.c
@@ -0,0 +1,356 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Watchdog driver for the K3 RTI module
+ *
+ * (c) Copyright 2019-2020 Texas Instruments Inc.
+ * All rights reserved.
+ */
+
+#include <linux/clk.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+#define DEFAULT_HEARTBEAT 60
+
+/* Max heartbeat is calculated at 32kHz source clock */
+#define MAX_HEARTBEAT	1000
+
+/* Timer register set definition */
+#define RTIDWDCTRL	0x90
+#define RTIDWDPRLD	0x94
+#define RTIWDSTATUS	0x98
+#define RTIWDKEY	0x9c
+#define RTIDWDCNTR	0xa0
+#define RTIWWDRXCTRL	0xa4
+#define RTIWWDSIZECTRL	0xa8
+
+#define RTIWWDRX_NMI	0xa
+
+#define RTIWWDSIZE_50P		0x50
+#define RTIWWDSIZE_25P		0x500
+#define RTIWWDSIZE_12P5		0x5000
+#define RTIWWDSIZE_6P25		0x50000
+#define RTIWWDSIZE_3P125	0x500000
+
+#define WDENABLE_KEY	0xa98559da
+
+#define WDKEY_SEQ0		0xe51a
+#define WDKEY_SEQ1		0xa35c
+
+#define WDT_PRELOAD_SHIFT	13
+
+#define WDT_PRELOAD_MAX		0xfff
+
+#define DWDST			BIT(1)
+
+static int heartbeat = DEFAULT_HEARTBEAT;
+
+/*
+ * struct to hold data for each WDT device
+ * @base - base io address of WD device
+ * @freq - source clock frequency of WDT
+ * @wdd  - hold watchdog device as is in WDT core
+ */
+struct rti_wdt_device {
+	void __iomem		*base;
+	unsigned long		freq;
+	struct watchdog_device	wdd;
+};
+
+static int rti_wdt_start(struct watchdog_device *wdd)
+{
+	u32 timer_margin;
+	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(wdd->parent);
+	if (ret)
+		return ret;
+
+	/* set timeout period */
+	timer_margin = (u64)wdd->timeout * wdt->freq;
+	timer_margin >>= WDT_PRELOAD_SHIFT;
+	if (timer_margin > WDT_PRELOAD_MAX)
+		timer_margin = WDT_PRELOAD_MAX;
+	writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD);
+
+	/*
+	 * RTI only supports a windowed mode, where the watchdog can only
+	 * be petted during the open window; not too early or not too late.
+	 * The HW configuration options only allow for the open window size
+	 * to be 50% or less than that; we obviouly want to configure the open
+	 * window as large as possible so we select the 50% option.
+	 */
+	wdd->min_hw_heartbeat_ms = 500 * wdd->timeout;
+
+	/* Generate NMI when wdt expires */
+	writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
+
+	/* Open window size 50%; this is the largest window size available */
+	writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
+
+	readl_relaxed(wdt->base + RTIWWDSIZECTRL);
+
+	/* enable watchdog */
+	writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
+	return 0;
+}
+
+static int rti_wdt_ping(struct watchdog_device *wdd)
+{
+	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
+
+	/* put watchdog in service state */
+	writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
+	/* put watchdog in active state */
+	writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
+
+	return 0;
+}
+
+static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
+{
+	/*
+	 * RTI only supports a windowed mode, where the watchdog can only
+	 * be petted during the open window; not too early or not too late.
+	 * The HW configuration options only allow for the open window size
+	 * to be 50% or less than that.
+	 */
+	switch (wsize) {
+	case RTIWWDSIZE_50P:
+		/* 50% open window => 50% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 500 * heartbeat;
+		break;
+
+	case RTIWWDSIZE_25P:
+		/* 25% open window => 75% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 750 * heartbeat;
+		break;
+
+	case RTIWWDSIZE_12P5:
+		/* 12.5% open window => 87.5% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 875 * heartbeat;
+		break;
+
+	case RTIWWDSIZE_6P25:
+		/* 6.5% open window => 93.5% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 935 * heartbeat;
+		break;
+
+	case RTIWWDSIZE_3P125:
+		/* 3.125% open window => 96.9% min heartbeat */
+		wdd->min_hw_heartbeat_ms = 969 * heartbeat;
+		break;
+
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd)
+{
+	u64 timer_counter;
+	u32 val;
+	struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
+
+	/* if timeout has occurred then return 0 */
+	val = readl_relaxed(wdt->base + RTIWDSTATUS);
+	if (val & DWDST)
+		return 0;
+
+	timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);
+
+	timer_counter *= 1000;
+
+	do_div(timer_counter, wdt->freq);
+
+	return timer_counter;
+}
+
+static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	return rti_wdt_get_timeleft_ms(wdd) / 1000;
+}
+
+static const struct watchdog_info rti_wdt_info = {
+	.options = WDIOF_KEEPALIVEPING,
+	.identity = "K3 RTI Watchdog",
+};
+
+static const struct watchdog_ops rti_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= rti_wdt_start,
+	.ping		= rti_wdt_ping,
+	.get_timeleft	= rti_wdt_get_timeleft,
+};
+
+static int rti_wdt_probe(struct platform_device *pdev)
+{
+	int ret = 0;
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+	struct rti_wdt_device *wdt;
+	struct clk *clk;
+	u32 last_ping = 0;
+
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	clk = clk_get(dev, NULL);
+	if (IS_ERR(clk))
+		return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
+
+	wdt->freq = clk_get_rate(clk);
+
+	clk_put(clk);
+
+	if (!wdt->freq) {
+		dev_err(dev, "Failed to get fck rate.\n");
+		return -EINVAL;
+	}
+
+	/*
+	 * If watchdog is running at 32k clock, it is not accurate.
+	 * Adjust frequency down in this case so that we don't pet
+	 * the watchdog too often.
+	 */
+	if (wdt->freq < 32768)
+		wdt->freq = wdt->freq * 9 / 10;
+
+	pm_runtime_enable(dev);
+	ret = pm_runtime_resume_and_get(dev);
+	if (ret < 0) {
+		pm_runtime_disable(&pdev->dev);
+		return dev_err_probe(dev, ret, "runtime pm failed\n");
+	}
+
+	platform_set_drvdata(pdev, wdt);
+
+	wdd = &wdt->wdd;
+	wdd->info = &rti_wdt_info;
+	wdd->ops = &rti_wdt_ops;
+	wdd->min_timeout = 1;
+	wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
+		wdt->freq * 1000;
+	wdd->parent = dev;
+
+	watchdog_set_drvdata(wdd, wdt);
+	watchdog_set_nowayout(wdd, 1);
+	watchdog_set_restart_priority(wdd, 128);
+
+	wdt->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(wdt->base)) {
+		ret = PTR_ERR(wdt->base);
+		goto err_iomap;
+	}
+
+	if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
+		int preset_heartbeat;
+		u32 time_left_ms;
+		u64 heartbeat_ms;
+		u32 wsize;
+
+		set_bit(WDOG_HW_RUNNING, &wdd->status);
+		time_left_ms = rti_wdt_get_timeleft_ms(wdd);
+		heartbeat_ms = readl(wdt->base + RTIDWDPRLD);
+		heartbeat_ms <<= WDT_PRELOAD_SHIFT;
+		heartbeat_ms *= 1000;
+		do_div(heartbeat_ms, wdt->freq);
+		preset_heartbeat = heartbeat_ms + 500;
+		preset_heartbeat /= 1000;
+		if (preset_heartbeat != heartbeat)
+			dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n");
+
+		heartbeat = preset_heartbeat;
+
+		wsize = readl(wdt->base + RTIWWDSIZECTRL);
+		ret = rti_wdt_setup_hw_hb(wdd, wsize);
+		if (ret) {
+			dev_err(dev, "bad window size.\n");
+			goto err_iomap;
+		}
+
+		last_ping = heartbeat_ms - time_left_ms;
+		if (time_left_ms > heartbeat_ms) {
+			dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n");
+			last_ping = 0;
+		}
+	}
+
+	watchdog_init_timeout(wdd, heartbeat, dev);
+
+	ret = watchdog_register_device(wdd);
+	if (ret) {
+		dev_err(dev, "cannot register watchdog device\n");
+		goto err_iomap;
+	}
+
+	if (last_ping)
+		watchdog_set_last_hw_keepalive(wdd, last_ping);
+
+	if (!watchdog_hw_running(wdd))
+		pm_runtime_put_sync(&pdev->dev);
+
+	return 0;
+
+err_iomap:
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+
+	return ret;
+}
+
+static int rti_wdt_remove(struct platform_device *pdev)
+{
+	struct rti_wdt_device *wdt = platform_get_drvdata(pdev);
+
+	watchdog_unregister_device(&wdt->wdd);
+
+	if (!pm_runtime_suspended(&pdev->dev))
+		pm_runtime_put(&pdev->dev);
+
+	pm_runtime_disable(&pdev->dev);
+
+	return 0;
+}
+
+static const struct of_device_id rti_wdt_of_match[] = {
+	{ .compatible = "ti,j7-rti-wdt", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
+
+static struct platform_driver rti_wdt_driver = {
+	.driver = {
+		.name = "rti-wdt",
+		.of_match_table = rti_wdt_of_match,
+	},
+	.probe = rti_wdt_probe,
+	.remove = rti_wdt_remove,
+};
+
+module_platform_driver(rti_wdt_driver);
+
+MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");
+MODULE_DESCRIPTION("K3 RTI Watchdog Driver");
+
+module_param(heartbeat, int, 0);
+MODULE_PARM_DESC(heartbeat,
+		 "Watchdog heartbeat period in seconds from 1 to "
+		 __MODULE_STRING(MAX_HEARTBEAT) ", default "
+		 __MODULE_STRING(DEFAULT_HEARTBEAT));
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:rti-wdt");