[PATCH v3 1/2] watchdog: add Intel MID watchdog driver support

[David Cohen <david.a.cohen@linux.intel.com>]

Add initial Intel MID watchdog driver support.

This driver is an initial implementation of generic Intel MID watchdog
driver. Currently it supports Intel Merrifield platform.

Signed-off-by: Eric Ernst <eric.ernst@intel.com>
Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
---
 drivers/watchdog/Kconfig         |  13 +++
 drivers/watchdog/Makefile        |   1 +
 drivers/watchdog/intel-mid_wdt.c | 187 +++++++++++++++++++++++++++++++++++++++
 include/linux/intel-mid_wdt.h    |  20 +++++
 4 files changed, 221 insertions(+)
 create mode 100644 drivers/watchdog/intel-mid_wdt.c
 create mode 100644 include/linux/intel-mid_wdt.h

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 79d25894343a..0e110c37aa5c 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -643,6 +643,19 @@ config INTEL_SCU_WATCHDOG
 
 	  To compile this driver as a module, choose M here.
 
+config INTEL_MID_WATCHDOG
+	tristate "Intel MID Watchdog Timer"
+	depends on X86_INTEL_MID
+	select WATCHDOG_CORE
+	---help---
+	  Watchdog timer driver built into the Intel SCU for Intel MID
+	  Platforms.
+
+	  This driver currently supports only the watchdog evolution
+	  implementation in SCU, available for Merrifield generation.
+
+	  To compile this driver as a module, choose M here.
+
 config ITCO_WDT
 	tristate "Intel TCO Timer/Watchdog"
 	depends on (X86 || IA64) && PCI
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 985a66cda76f..b927e7496eb4 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -113,6 +113,7 @@ obj-$(CONFIG_W83977F_WDT) += w83977f_wdt.o
 obj-$(CONFIG_MACHZ_WDT) += machzwd.o
 obj-$(CONFIG_SBC_EPX_C3_WATCHDOG) += sbc_epx_c3.o
 obj-$(CONFIG_INTEL_SCU_WATCHDOG) += intel_scu_watchdog.o
+obj-$(CONFIG_INTEL_MID_WATCHDOG) += intel-mid_wdt.o
 
 # M32R Architecture
 
diff --git a/drivers/watchdog/intel-mid_wdt.c b/drivers/watchdog/intel-mid_wdt.c
new file mode 100644
index 000000000000..d8bf3c3cd2b7
--- /dev/null
+++ b/drivers/watchdog/intel-mid_wdt.c
@@ -0,0 +1,187 @@
+/*
+ *      intel-mid_wdt: generic Intel MID SCU watchdog driver
+ *
+ *      Platforms supported so far:
+ *      - Merrifield only
+ *
+ *      Copyright (C) 2014 Intel Corporation. All rights reserved.
+ *      Contact: David Cohen <david.a.cohen@linux.intel.com>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of version 2 of the GNU General
+ *      Public License as published by the Free Software Foundation.
+ */
+
+#include <linux/intel-mid_wdt.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/nmi.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#include <asm/intel_scu_ipc.h>
+#include <asm/intel-mid.h>
+
+#define IPC_WATCHDOG 0xf8
+
+#define MID_WDT_PRETIMEOUT		15
+#define MID_WDT_TIMEOUT_MIN		(1 + MID_WDT_PRETIMEOUT)
+#define MID_WDT_TIMEOUT_MAX		170
+#define MID_WDT_DEFAULT_TIMEOUT		90
+
+/* SCU watchdog messages */
+enum {
+	SCU_WATCHDOG_START = 0,
+	SCU_WATCHDOG_STOP,
+	SCU_WATCHDOG_KEEPALIVE,
+};
+
+static inline int wdt_command(int sub, u32 *in, int inlen)
+{
+	return intel_scu_ipc_command(IPC_WATCHDOG, sub, in, inlen, NULL, 0);
+}
+
+static int wdt_start(struct watchdog_device *wd)
+{
+	int ret, in_size;
+	int timeout = wd->timeout;
+	struct ipc_wd_start {
+		u32 pretimeout;
+		u32 timeout;
+	} ipc_wd_start = { timeout - MID_WDT_PRETIMEOUT, timeout };
+
+	/*
+	 * SCU expects the input size for watchdog IPC to
+	 * be based on double-word
+	 */
+	in_size = (sizeof(ipc_wd_start) + 3) / 4;
+
+	ret = wdt_command(SCU_WATCHDOG_START, (u32 *)&ipc_wd_start, in_size);
+	if (ret) {
+		struct device *dev = watchdog_get_drvdata(wd);
+		dev_crit(dev, "error starting watchdog: %d\n", ret);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int wdt_ping(struct watchdog_device *wd)
+{
+	int ret;
+
+	ret = wdt_command(SCU_WATCHDOG_KEEPALIVE, NULL, 0);
+	if (ret) {
+		struct device *dev = watchdog_get_drvdata(wd);
+		dev_crit(dev, "Error executing keepalive: 0x%x\n", ret);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static int wdt_stop(struct watchdog_device *wd)
+{
+	int ret;
+
+	ret = wdt_command(SCU_WATCHDOG_STOP, NULL, 0);
+	if (ret) {
+		struct device *dev = watchdog_get_drvdata(wd);
+		dev_crit(dev, "Error stopping watchdog: 0x%x\n", ret);
+		return -EIO;
+	}
+
+	return 0;
+}
+
+static irqreturn_t mid_wdt_warning_irq(int irq, void *dev_id)
+{
+	panic("Kernel Watchdog");
+
+	/* This code should not be reached */
+	return IRQ_HANDLED;
+}
+
+static const struct watchdog_info mid_wdt_info = {
+	.identity = "Intel MID SCU watchdog",
+	.options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT,
+};
+
+static const struct watchdog_ops mid_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = wdt_start,
+	.stop = wdt_stop,
+	.ping = wdt_ping,
+};
+
+static int mid_wdt_probe(struct platform_device *pdev)
+{
+	struct watchdog_device *wdt_dev;
+	struct intel_mid_wdt_pdata *pdata = pdev->dev.platform_data;
+	int ret;
+
+	if (!pdata) {
+		dev_err(&pdev->dev, "missing platform data\n");
+		return -EINVAL;
+	}
+
+	if (pdata->probe) {
+		ret = pdata->probe();
+		if (ret)
+			return ret;
+	}
+
+	wdt_dev = devm_kzalloc(&pdev->dev, sizeof(*wdt_dev), GFP_KERNEL);
+	if (!wdt_dev)
+		return -ENOMEM;
+
+	wdt_dev->info = &mid_wdt_info;
+	wdt_dev->ops = &mid_wdt_ops;
+	wdt_dev->min_timeout = MID_WDT_TIMEOUT_MIN;
+	wdt_dev->max_timeout = MID_WDT_TIMEOUT_MAX;
+	wdt_dev->timeout = MID_WDT_DEFAULT_TIMEOUT;
+
+	watchdog_set_drvdata(wdt_dev, &pdev->dev);
+	platform_set_drvdata(pdev, wdt_dev);
+
+	ret = devm_request_irq(&pdev->dev, pdata->irq, mid_wdt_warning_irq,
+			       IRQF_SHARED | IRQF_NO_SUSPEND, "watchdog",
+			       wdt_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "error requesting warning irq %d\n",
+			pdata->irq);
+		return ret;
+	}
+
+	ret = watchdog_register_device(wdt_dev);
+	if (ret) {
+		dev_err(&pdev->dev, "error registering watchdog device\n");
+		return ret;
+	}
+
+	dev_info(&pdev->dev, "Intel MID watchdog device probed\n");
+
+	return 0;
+}
+
+static int mid_wdt_remove(struct platform_device *pdev)
+{
+	struct watchdog_device *wd = platform_get_drvdata(pdev);
+	watchdog_unregister_device(wd);
+	return 0;
+}
+
+static struct platform_driver mid_wdt_driver = {
+	.probe		= mid_wdt_probe,
+	.remove		= mid_wdt_remove,
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "intel_mid_wdt",
+	},
+};
+
+module_platform_driver(mid_wdt_driver);
+
+MODULE_AUTHOR("David Cohen <david.a.cohen@linux.intel.com>");
+MODULE_DESCRIPTION("Watchdog Driver for Intel MID platform");
+MODULE_LICENSE("GPL");
diff --git a/include/linux/intel-mid_wdt.h b/include/linux/intel-mid_wdt.h
new file mode 100644
index 000000000000..705dff1c62f8
--- /dev/null
+++ b/include/linux/intel-mid_wdt.h
@@ -0,0 +1,20 @@
+/*
+ *      intel-mid_wdt: generic Intel MID SCU watchdog driver
+ *
+ *      Copyright (C) 2014 Intel Corporation. All rights reserved.
+ *      Contact: David Cohen <david.a.cohen@linux.intel.com>
+ *
+ *      This program is free software; you can redistribute it and/or
+ *      modify it under the terms of version 2 of the GNU General
+ *      Public License as published by the Free Software Foundation.
+ */
+
+#ifndef __INTEL_MID_WDT_H__
+#define __INTEL_MID_WDT_H__
+
+struct intel_mid_wdt_pdata {
+	int irq;
+	int (*probe)(void);
+};
+
+#endif /*__INTEL_MID_WDT_H__*/
-- 
1.9.1