1 files changed, 340 insertions, 0 deletions
diff --git a/drivers/watchdog/imgpdc_wdt.c b/drivers/watchdog/imgpdc_wdt.c
new file mode 100644
index 000000000..a3134ffa5
--- /dev/null
+++ b/drivers/watchdog/imgpdc_wdt.c
@@ -0,0 +1,340 @@
+/*
+ * Imagination Technologies PowerDown Controller Watchdog Timer.
+ *
+ * Copyright (c) 2014 Imagination Technologies Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ *
+ * Based on drivers/watchdog/sunxi_wdt.c Copyright (c) 2013 Carlo Caione
+ *                                                     2012 Henrik Nordstrom
+ *
+ * Notes
+ * -----
+ * The timeout value is rounded to the next power of two clock cycles.
+ * This is configured using the PDC_WDT_CONFIG register, according to this
+ * formula:
+ *
+ *     timeout = 2^(delay + 1) clock cycles
+ *
+ * Where 'delay' is the value written in PDC_WDT_CONFIG register.
+ *
+ * Therefore, the hardware only allows to program watchdog timeouts, expressed
+ * as a power of two number of watchdog clock cycles. The current implementation
+ * guarantees that the actual watchdog timeout will be _at least_ the value
+ * programmed in the imgpdg_wdt driver.
+ *
+ * The following table shows how the user-configured timeout relates
+ * to the actual hardware timeout (watchdog clock @ 40000 Hz):
+ *
+ * input timeout | WD_DELAY | actual timeout
+ * -----------------------------------
+ *      10       |   18     |  13 seconds
+ *      20       |   19     |  26 seconds
+ *      30       |   20     |  52 seconds
+ *      60       |   21     |  104 seconds
+ *
+ * Albeit coarse, this granularity would suffice most watchdog uses.
+ * If the platform allows it, the user should be able to change the watchdog
+ * clock rate and achieve a finer timeout granularity.
+ */
+
+#include <linux/clk.h>
+#include <linux/io.h>
+#include <linux/log2.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/watchdog.h>
+
+/* registers */
+#define PDC_WDT_SOFT_RESET		0x00
+#define PDC_WDT_CONFIG			0x04
+  #define PDC_WDT_CONFIG_ENABLE		BIT(31)
+  #define PDC_WDT_CONFIG_DELAY_MASK	0x1f
+
+#define PDC_WDT_TICKLE1			0x08
+#define PDC_WDT_TICKLE1_MAGIC		0xabcd1234
+#define PDC_WDT_TICKLE2			0x0c
+#define PDC_WDT_TICKLE2_MAGIC		0x4321dcba
+
+#define PDC_WDT_TICKLE_STATUS_MASK	0x7
+#define PDC_WDT_TICKLE_STATUS_SHIFT	0
+#define PDC_WDT_TICKLE_STATUS_HRESET	0x0  /* Hard reset */
+#define PDC_WDT_TICKLE_STATUS_TIMEOUT	0x1  /* Timeout */
+#define PDC_WDT_TICKLE_STATUS_TICKLE	0x2  /* Tickled incorrectly */
+#define PDC_WDT_TICKLE_STATUS_SRESET	0x3  /* Soft reset */
+#define PDC_WDT_TICKLE_STATUS_USER	0x4  /* User reset */
+
+/* Timeout values are in seconds */
+#define PDC_WDT_MIN_TIMEOUT		1
+#define PDC_WDT_DEF_TIMEOUT		64
+
+static int heartbeat;
+module_param(heartbeat, int, 0);
+MODULE_PARM_DESC(heartbeat, "Watchdog heartbeats in seconds "
+	"(default=" __MODULE_STRING(PDC_WDT_DEF_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) ")");
+
+struct pdc_wdt_dev {
+	struct watchdog_device wdt_dev;
+	struct clk *wdt_clk;
+	struct clk *sys_clk;
+	void __iomem *base;
+};
+
+static int pdc_wdt_keepalive(struct watchdog_device *wdt_dev)
+{
+	struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
+
+	writel(PDC_WDT_TICKLE1_MAGIC, wdt->base + PDC_WDT_TICKLE1);
+	writel(PDC_WDT_TICKLE2_MAGIC, wdt->base + PDC_WDT_TICKLE2);
+
+	return 0;
+}
+
+static int pdc_wdt_stop(struct watchdog_device *wdt_dev)
+{
+	unsigned int val;
+	struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
+
+	val = readl(wdt->base + PDC_WDT_CONFIG);
+	val &= ~PDC_WDT_CONFIG_ENABLE;
+	writel(val, wdt->base + PDC_WDT_CONFIG);
+
+	/* Must tickle to finish the stop */
+	pdc_wdt_keepalive(wdt_dev);
+
+	return 0;
+}
+
+static void __pdc_wdt_set_timeout(struct pdc_wdt_dev *wdt)
+{
+	unsigned long clk_rate = clk_get_rate(wdt->wdt_clk);
+	unsigned int val;
+
+	val = readl(wdt->base + PDC_WDT_CONFIG) & ~PDC_WDT_CONFIG_DELAY_MASK;
+	val |= order_base_2(wdt->wdt_dev.timeout * clk_rate) - 1;
+	writel(val, wdt->base + PDC_WDT_CONFIG);
+}
+
+static int pdc_wdt_set_timeout(struct watchdog_device *wdt_dev,
+			       unsigned int new_timeout)
+{
+	struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
+
+	wdt->wdt_dev.timeout = new_timeout;
+
+	__pdc_wdt_set_timeout(wdt);
+
+	return 0;
+}
+
+/* Start the watchdog timer (delay should already be set) */
+static int pdc_wdt_start(struct watchdog_device *wdt_dev)
+{
+	unsigned int val;
+	struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
+
+	__pdc_wdt_set_timeout(wdt);
+
+	val = readl(wdt->base + PDC_WDT_CONFIG);
+	val |= PDC_WDT_CONFIG_ENABLE;
+	writel(val, wdt->base + PDC_WDT_CONFIG);
+
+	return 0;
+}
+
+static int pdc_wdt_restart(struct watchdog_device *wdt_dev,
+			   unsigned long action, void *data)
+{
+	struct pdc_wdt_dev *wdt = watchdog_get_drvdata(wdt_dev);
+
+	/* Assert SOFT_RESET */
+	writel(0x1, wdt->base + PDC_WDT_SOFT_RESET);
+
+	return 0;
+}
+
+static const struct watchdog_info pdc_wdt_info = {
+	.identity	= "IMG PDC Watchdog",
+	.options	= WDIOF_SETTIMEOUT |
+			  WDIOF_KEEPALIVEPING |
+			  WDIOF_MAGICCLOSE,
+};
+
+static const struct watchdog_ops pdc_wdt_ops = {
+	.owner		= THIS_MODULE,
+	.start		= pdc_wdt_start,
+	.stop		= pdc_wdt_stop,
+	.ping		= pdc_wdt_keepalive,
+	.set_timeout	= pdc_wdt_set_timeout,
+	.restart        = pdc_wdt_restart,
+};
+
+static int pdc_wdt_probe(struct platform_device *pdev)
+{
+	u64 div;
+	int ret, val;
+	unsigned long clk_rate;
+	struct resource *res;
+	struct pdc_wdt_dev *pdc_wdt;
+
+	pdc_wdt = devm_kzalloc(&pdev->dev, sizeof(*pdc_wdt), GFP_KERNEL);
+	if (!pdc_wdt)
+		return -ENOMEM;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	pdc_wdt->base = devm_ioremap_resource(&pdev->dev, res);
+	if (IS_ERR(pdc_wdt->base))
+		return PTR_ERR(pdc_wdt->base);
+
+	pdc_wdt->sys_clk = devm_clk_get(&pdev->dev, "sys");
+	if (IS_ERR(pdc_wdt->sys_clk)) {
+		dev_err(&pdev->dev, "failed to get the sys clock\n");
+		return PTR_ERR(pdc_wdt->sys_clk);
+	}
+
+	pdc_wdt->wdt_clk = devm_clk_get(&pdev->dev, "wdt");
+	if (IS_ERR(pdc_wdt->wdt_clk)) {
+		dev_err(&pdev->dev, "failed to get the wdt clock\n");
+		return PTR_ERR(pdc_wdt->wdt_clk);
+	}
+
+	ret = clk_prepare_enable(pdc_wdt->sys_clk);
+	if (ret) {
+		dev_err(&pdev->dev, "could not prepare or enable sys clock\n");
+		return ret;
+	}
+
+	ret = clk_prepare_enable(pdc_wdt->wdt_clk);
+	if (ret) {
+		dev_err(&pdev->dev, "could not prepare or enable wdt clock\n");
+		goto disable_sys_clk;
+	}
+
+	/* We use the clock rate to calculate the max timeout */
+	clk_rate = clk_get_rate(pdc_wdt->wdt_clk);
+	if (clk_rate == 0) {
+		dev_err(&pdev->dev, "failed to get clock rate\n");
+		ret = -EINVAL;
+		goto disable_wdt_clk;
+	}
+
+	if (order_base_2(clk_rate) > PDC_WDT_CONFIG_DELAY_MASK + 1) {
+		dev_err(&pdev->dev, "invalid clock rate\n");
+		ret = -EINVAL;
+		goto disable_wdt_clk;
+	}
+
+	if (order_base_2(clk_rate) == 0)
+		pdc_wdt->wdt_dev.min_timeout = PDC_WDT_MIN_TIMEOUT + 1;
+	else
+		pdc_wdt->wdt_dev.min_timeout = PDC_WDT_MIN_TIMEOUT;
+
+	pdc_wdt->wdt_dev.info = &pdc_wdt_info;
+	pdc_wdt->wdt_dev.ops = &pdc_wdt_ops;
+
+	div = 1ULL << (PDC_WDT_CONFIG_DELAY_MASK + 1);
+	do_div(div, clk_rate);
+	pdc_wdt->wdt_dev.max_timeout = div;
+	pdc_wdt->wdt_dev.timeout = PDC_WDT_DEF_TIMEOUT;
+	pdc_wdt->wdt_dev.parent = &pdev->dev;
+	watchdog_set_drvdata(&pdc_wdt->wdt_dev, pdc_wdt);
+
+	watchdog_init_timeout(&pdc_wdt->wdt_dev, heartbeat, &pdev->dev);
+
+	pdc_wdt_stop(&pdc_wdt->wdt_dev);
+
+	/* Find what caused the last reset */
+	val = readl(pdc_wdt->base + PDC_WDT_TICKLE1);
+	val = (val & PDC_WDT_TICKLE_STATUS_MASK) >> PDC_WDT_TICKLE_STATUS_SHIFT;
+	switch (val) {
+	case PDC_WDT_TICKLE_STATUS_TICKLE:
+	case PDC_WDT_TICKLE_STATUS_TIMEOUT:
+		pdc_wdt->wdt_dev.bootstatus |= WDIOF_CARDRESET;
+		dev_info(&pdev->dev,
+			 "watchdog module last reset due to timeout\n");
+		break;
+	case PDC_WDT_TICKLE_STATUS_HRESET:
+		dev_info(&pdev->dev,
+			 "watchdog module last reset due to hard reset\n");
+		break;
+	case PDC_WDT_TICKLE_STATUS_SRESET:
+		dev_info(&pdev->dev,
+			 "watchdog module last reset due to soft reset\n");
+		break;
+	case PDC_WDT_TICKLE_STATUS_USER:
+		dev_info(&pdev->dev,
+			 "watchdog module last reset due to user reset\n");
+		break;
+	default:
+		dev_info(&pdev->dev,
+			 "contains an illegal status code (%08x)\n", val);
+		break;
+	}
+
+	watchdog_set_nowayout(&pdc_wdt->wdt_dev, nowayout);
+	watchdog_set_restart_priority(&pdc_wdt->wdt_dev, 128);
+
+	platform_set_drvdata(pdev, pdc_wdt);
+
+	ret = watchdog_register_device(&pdc_wdt->wdt_dev);
+	if (ret)
+		goto disable_wdt_clk;
+
+	return 0;
+
+disable_wdt_clk:
+	clk_disable_unprepare(pdc_wdt->wdt_clk);
+disable_sys_clk:
+	clk_disable_unprepare(pdc_wdt->sys_clk);
+	return ret;
+}
+
+static void pdc_wdt_shutdown(struct platform_device *pdev)
+{
+	struct pdc_wdt_dev *pdc_wdt = platform_get_drvdata(pdev);
+
+	pdc_wdt_stop(&pdc_wdt->wdt_dev);
+}
+
+static int pdc_wdt_remove(struct platform_device *pdev)
+{
+	struct pdc_wdt_dev *pdc_wdt = platform_get_drvdata(pdev);
+
+	pdc_wdt_stop(&pdc_wdt->wdt_dev);
+	watchdog_unregister_device(&pdc_wdt->wdt_dev);
+	clk_disable_unprepare(pdc_wdt->wdt_clk);
+	clk_disable_unprepare(pdc_wdt->sys_clk);
+
+	return 0;
+}
+
+static const struct of_device_id pdc_wdt_match[] = {
+	{ .compatible = "img,pdc-wdt" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, pdc_wdt_match);
+
+static struct platform_driver pdc_wdt_driver = {
+	.driver = {
+		.name = "imgpdc-wdt",
+		.of_match_table	= pdc_wdt_match,
+	},
+	.probe = pdc_wdt_probe,
+	.remove = pdc_wdt_remove,
+	.shutdown = pdc_wdt_shutdown,
+};
+module_platform_driver(pdc_wdt_driver);
+
+MODULE_AUTHOR("Jude Abraham <Jude.Abraham@imgtec.com>");
+MODULE_AUTHOR("Naidu Tellapati <Naidu.Tellapati@imgtec.com>");
+MODULE_DESCRIPTION("Imagination Technologies PDC Watchdog Timer Driver");
+MODULE_LICENSE("GPL v2");