Date:	Fri, 25 Nov 2011 21:02:39 +0100
From:	Marc Vertes <marc.vertes@...fox.com>
To:	wim@...ana.be
Cc:	w.sang@...gutronix.de, mad_soft@...ox.ru,
	linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
	HaraldWelte@...tech.com, broonie@...nsource.wolfsonmicro.com
Subject: Re: [PATCH RFC] watchdog: add a new driver for VIA chipsets

Add a new driver for the hardware watchdog timer on VIA chipsets.
This driver uses the new watchdog framework.
Remember to switch on PnP in BIOS.
Tested on a Artigo A1100, VX855 chipset.

Signed-off-by: Marc Vertes <marc.vertes@...fox.com>

---

 Kconfig   |   14 +++
 Makefile  |    1 
 via_wdt.c |  268 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 283 insertions(+)

--- linux-3.2-rc3/drivers/watchdog/Makefile.orig	2011-11-24 05:20:28.000000000 +0100
+++ linux-3.2-rc3/drivers/watchdog/Makefile	2011-11-25 20:41:58.098297812 +0100
@@ -99,6 +99,7 @@ obj-$(CONFIG_SBC7240_WDT) += sbc7240_wdt
 obj-$(CONFIG_CPU5_WDT) += cpu5wdt.o
 obj-$(CONFIG_SMSC_SCH311X_WDT) += sch311x_wdt.o
 obj-$(CONFIG_SMSC37B787_WDT) += smsc37b787_wdt.o
+obj-$(CONFIG_VIA_WDT) += via_wdt.o
 obj-$(CONFIG_W83627HF_WDT) += w83627hf_wdt.o
 obj-$(CONFIG_W83697HF_WDT) += w83697hf_wdt.o
 obj-$(CONFIG_W83697UG_WDT) += w83697ug_wdt.o
--- linux-3.2-rc3/drivers/watchdog/via_wdt.c.orig	2011-11-25 20:35:19.219272614 +0100
+++ linux-3.2-rc3/drivers/watchdog/via_wdt.c	2011-11-25 20:35:53.128104742 +0100
@@ -0,0 +1,268 @@
+/*
+ * VIA Chipset Watchdog Driver
+ *
+ * Copyright (C) 2011 Sigfox
+ * License terms: GNU General Public License (GPL) version 2
+ * Author: Marc Vertes <marc.vertes@...fox.com>
+ * Based on a preliminary version from Harald Welte <HaraldWelte@...tech.com>
+ * Timer code by Wim Van Sebroeck <wim@...ana.be>
+ *
+ * Caveat: PnP must be enabled in BIOS to allow full access to watchdog
+ * control registers. If not, the watchdog must be configured in BIOS manually.
+ */
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/timer.h>
+#include <linux/watchdog.h>
+
+/* Configuration registers relative to the pci device */
+#define VIA_WDT_MMIO_BASE	0xe8	/* MMIO region base address */
+#define VIA_WDT_CONF		0xec	/* watchdog enable state */
+
+/* Relevant bits for the VIA_WDT_CONF register */
+#define VIA_WDT_CONF_ENABLE	0x01	/* 1: enable watchdog */
+#define VIA_WDT_CONF_MMIO	0x02	/* 1: enable watchdog MMIO */
+
+/*
+ * The MMIO region contains the watchog control register and the
+ * hardware timer counter.
+ */
+#define VIA_WDT_MMIO_LEN	8	/* MMIO region length in bytes */
+#define VIA_WDT_CTL		0	/* MMIO addr+0: state/control reg. */
+#define VIA_WDT_COUNT		4	/* MMIO addr+4: timer counter reg. */
+
+/* Bits for the VIA_WDT_CTL register */
+#define VIA_WDT_RUNNING		0x01	/* 0: stop, 1: running */
+#define VIA_WDT_FIRED		0x02	/* 1: restarted by expired watchdog */
+#define VIA_WDT_PWROFF		0x04	/* 0: reset, 1: poweroff */
+#define VIA_WDT_DISABLED	0x08	/* 1: timer is disabled */
+#define VIA_WDT_TRIGGER		0x80	/* 1: start a new countdown */
+
+/* Hardware heartbeat in seconds */
+#define WDT_HW_HEARTBEAT 1
+
+/* Timer heartbeat (500ms) */
+#define WDT_HEARTBEAT	(HZ/2)	/* should be <= ((WDT_HW_HEARTBEAT*HZ)/2) */
+
+/* User space timeout in seconds */
+#define WDT_TIMEOUT_MAX	1023	/* approx. 17 min. */
+#define WDT_TIMEOUT	60
+static int timeout = WDT_TIMEOUT;
+module_param(timeout, int, 0);
+MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds, between 1 and 1023 "
+	"(default = " __MODULE_STRING(WDT_TIMEOUT) ")");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started "
+	"(default = " __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+static struct watchdog_device wdt_dev;
+static struct resource wdt_res;
+static void __iomem *wdt_mem;
+static unsigned int mmio;
+static void wdt_timer_tick(unsigned long data);
+static DEFINE_TIMER(timer, wdt_timer_tick, 0, 0);
+					/* The timer that pings the watchdog */
+static unsigned long next_heartbeat;	/* the next_heartbeat for the timer */
+
+static inline void wdt_reset(void)
+{
+	unsigned int ctl = readl(wdt_mem);
+
+	writel(ctl | VIA_WDT_TRIGGER, wdt_mem);
+}
+
+/*
+ * Timer tick: the timer will make sure that the watchdog timer hardware
+ * is being reset in time. The conditions to do this are:
+ *  1) the watchog timer has been started and /dev/watchdog is open
+ *     and there is still time left before userspace should send the
+ *     next heartbeat/ping. (note: the internal heartbeat is much smaller
+ *     then the external/userspace heartbeat).
+ *  2) the watchdog timer has been stopped by userspace.
+ */
+static void wdt_timer_tick(unsigned long data)
+{
+	if (time_before(jiffies, next_heartbeat) ||
+	   (!test_bit(WDOG_ACTIVE, &wdt_dev.status))) {
+		wdt_reset();
+		mod_timer(&timer, jiffies + WDT_HEARTBEAT);
+	} else
+		pr_crit("I will reboot your machine !\n");
+}
+
+static int wdt_ping(struct watchdog_device *wdd)
+{
+	/* calculate when the next userspace timeout will be */
+	next_heartbeat = jiffies + timeout * HZ;
+	return 0;
+}
+
+static int wdt_start(struct watchdog_device *wdd)
+{
+	unsigned int ctl = readl(wdt_mem);
+
+	writel(timeout, wdt_mem + VIA_WDT_COUNT);
+	writel(ctl | VIA_WDT_RUNNING | VIA_WDT_TRIGGER, wdt_mem);
+	wdt_ping(wdd);
+	mod_timer(&timer, jiffies + WDT_HEARTBEAT);
+	return 0;
+}
+
+static int wdt_stop(struct watchdog_device *wdd)
+{
+	unsigned int ctl = readl(wdt_mem);
+
+	writel(ctl & ~VIA_WDT_RUNNING, wdt_mem);
+	return 0;
+}
+
+static int wdt_set_timeout(struct watchdog_device *wdd,
+			   unsigned int new_timeout)
+{
+	if (new_timeout < 1 || new_timeout > WDT_TIMEOUT_MAX)
+		return -EINVAL;
+	writel(new_timeout, wdt_mem + VIA_WDT_COUNT);
+	timeout = new_timeout;
+	return 0;
+}
+
+static const struct watchdog_info wdt_info = {
+	.identity =	"VIA watchdog",
+	.options =	WDIOF_CARDRESET |
+			WDIOF_SETTIMEOUT |
+			WDIOF_MAGICCLOSE |
+			WDIOF_KEEPALIVEPING,
+};
+
+static const struct watchdog_ops wdt_ops = {
+	.owner =	THIS_MODULE,
+	.start =	wdt_start,
+	.stop =		wdt_stop,
+	.ping =		wdt_ping,
+	.set_timeout =	wdt_set_timeout,
+};
+
+static struct watchdog_device wdt_dev = {
+	.info =		&wdt_info,
+	.ops =		&wdt_ops,
+};
+
+static int __devinit wdt_probe(struct pci_dev *pdev,
+			       const struct pci_device_id *ent)
+{
+	unsigned char conf;
+	int ret = -ENODEV;
+
+	if (pci_enable_device(pdev)) {
+		dev_err(&pdev->dev, "cannot enable PCI device\n");
+		return -ENODEV;
+	}
+
+	/*
+	 * Allocate a MMIO region which contains watchdog control register
+	 * and counter, then configure the watchdog to use this region.
+	 * This is possible only if PnP is properly enabled in BIOS.
+	 * If not, the watchdog must be configured in BIOS manually.
+	 */
+	if (allocate_resource(&iomem_resource, &wdt_res, VIA_WDT_MMIO_LEN,
+			      0xf0000000, 0xffffff00, 0xff, NULL, NULL)) {
+		dev_err(&pdev->dev, "MMIO allocation failed\n");
+		goto err_out_disable_device;
+	}
+
+	pci_write_config_dword(pdev, VIA_WDT_MMIO_BASE, wdt_res.start);
+	pci_read_config_byte(pdev, VIA_WDT_CONF, &conf);
+	conf |= VIA_WDT_CONF_ENABLE | VIA_WDT_CONF_MMIO;
+	pci_write_config_byte(pdev, VIA_WDT_CONF, conf);
+
+	pci_read_config_dword(pdev, VIA_WDT_MMIO_BASE, &mmio);
+	if (mmio) {
+		dev_info(&pdev->dev, "VIA Chipset watchdog MMIO: %x\n", mmio);
+	} else {
+		dev_err(&pdev->dev, "MMIO setting failed. Check BIOS.\n");
+		goto err_out_resource;
+	}
+
+	if (!request_mem_region(mmio, VIA_WDT_MMIO_LEN, "via_wdt")) {
+		dev_err(&pdev->dev, "MMIO region busy\n");
+		goto err_out_resource;
+	}
+
+	wdt_mem = ioremap(mmio, VIA_WDT_MMIO_LEN);
+	if (wdt_mem == NULL) {
+		dev_err(&pdev->dev, "cannot remap VIA wdt MMIO registers\n");
+		goto err_out_release;
+	}
+
+	wdt_dev.timeout = timeout;
+	if (nowayout)
+		set_bit(WDOG_NO_WAY_OUT, &wdt_dev.status);
+
+	if (readl(wdt_mem) & VIA_WDT_FIRED)
+		wdt_dev.bootstatus |= WDIOF_CARDRESET;
+
+	ret = watchdog_register_device(&wdt_dev);
+	if (ret)
+		goto err_out_iounmap;
+
+	/* start triggering, in case of watchdog already enabled by BIOS */
+	mod_timer(&timer, jiffies + WDT_HEARTBEAT);
+	return 0;
+
+err_out_iounmap:
+	iounmap(wdt_mem);
+err_out_release:
+	release_mem_region(mmio, VIA_WDT_MMIO_LEN);
+err_out_resource:
+	release_resource(&wdt_res);
+err_out_disable_device:
+	pci_disable_device(pdev);
+	return ret;
+}
+
+static void __devexit wdt_remove(struct pci_dev *pdev)
+{
+	watchdog_unregister_device(&wdt_dev);
+	del_timer(&timer);
+	iounmap(wdt_mem);
+	release_mem_region(mmio, VIA_WDT_MMIO_LEN);
+	release_resource(&wdt_res);
+	pci_disable_device(pdev);
+}
+
+DEFINE_PCI_DEVICE_TABLE(wdt_pci_table) = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_CX700) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX800) },
+	{ PCI_DEVICE(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_VX855) },
+	{ 0 }
+};
+
+static struct pci_driver wdt_driver = {
+	.name		= "via_wdt",
+	.id_table	= wdt_pci_table,
+	.probe		= wdt_probe,
+	.remove		= __devexit_p(wdt_remove),
+};
+
+static int __init wdt_init(void)
+{
+	if (timeout < 1 || timeout > WDT_TIMEOUT_MAX)
+		timeout = WDT_TIMEOUT;
+	return pci_register_driver(&wdt_driver);
+}
+
+static void __exit wdt_exit(void)
+{
+	pci_unregister_driver(&wdt_driver);
+}
+
+module_init(wdt_init);
+module_exit(wdt_exit);
+
+MODULE_AUTHOR("Marc Vertes");
+MODULE_DESCRIPTION("Driver for watchdog timer on VIA chipset");
+MODULE_LICENSE("GPL");
--- linux-3.2-rc3/drivers/watchdog/Kconfig.orig	2011-11-24 05:20:28.000000000 +0100
+++ linux-3.2-rc3/drivers/watchdog/Kconfig	2011-11-25 20:42:46.826056558 +0100
@@ -772,6 +772,20 @@ config SMSC37B787_WDT
 
 	  Most people will say N.
 
+config VIA_WDT
+	tristate "VIA Watchdog Timer"
+	depends on X86
+	select WATCHDOG_CORE
+	---help---
+	This is the driver for the hardware watchdog timer on VIA
+	southbridge chipset CX700, VX800, VX855. Watchdog setup
+	in BIOS is required.
+
+	To compile this driver as a module, choose M here; the module
+	will be called via_wdt.
+
+	Most people will say N.
+
 config W83627HF_WDT
 	tristate "W83627HF/W83627DHG Watchdog Timer"
 	depends on X86
--
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