[WATCHDOG] U300 COH 901 327 watchdog driver

This patch adds support for the U300 COH 901 327 watchdog for the
U300 platform recently added to RMK:s ARM tree.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

3 files changed, 548 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 373c22fd24e..631599b7e6a 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -240,6 +240,16 @@ config ORION_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called orion_wdt.
 
+config COH901327_WATCHDOG
+	bool "ST-Ericsson COH 901 327 watchdog"
+	depends on ARCH_U300
+	default y if MACH_U300
+	help
+	  Say Y here to include Watchdog timer support for the
+	  watchdog embedded into the ST-Ericsson U300 series platforms.
+	  This watchdog is used to reset the system and thus cannot be
+	  compiled as a module.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 7231a150086..c3a22d3d549 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -41,6 +41,7 @@ obj-$(CONFIG_PNX4008_WATCHDOG) += pnx4008_wdt.o
 obj-$(CONFIG_IOP_WATCHDOG) += iop_wdt.o
 obj-$(CONFIG_DAVINCI_WATCHDOG) += davinci_wdt.o
 obj-$(CONFIG_ORION_WATCHDOG) += orion_wdt.o
+obj-$(CONFIG_COH901327_WATCHDOG) += coh901327_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/coh901327_wdt.c b/drivers/watchdog/coh901327_wdt.c
new file mode 100644
index 00000000000..fecb307d28e
--- /dev/null
+++ b/drivers/watchdog/coh901327_wdt.c
@@ -0,0 +1,537 @@
+/*
+ * coh901327_wdt.c
+ *
+ * Copyright (C) 2008-2009 ST-Ericsson AB
+ * License terms: GNU General Public License (GPL) version 2
+ * Watchdog driver for the ST-Ericsson AB COH 901 327 IP core
+ * Author: Linus Walleij <linus.walleij@stericsson.com>
+ */
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/interrupt.h>
+#include <linux/pm.h>
+#include <linux/platform_device.h>
+#include <linux/io.h>
+#include <linux/bitops.h>
+#include <linux/uaccess.h>
+#include <linux/clk.h>
+
+#define DRV_NAME "WDOG COH 901 327"
+
+/*
+ * COH 901 327 register definitions
+ */
+
+/* WDOG_FEED Register 32bit (-/W) */
+#define U300_WDOG_FR							0x00
+#define U300_WDOG_FR_FEED_RESTART_TIMER					0xFEEDU
+/* WDOG_TIMEOUT Register 32bit (R/W) */
+#define U300_WDOG_TR							0x04
+#define U300_WDOG_TR_TIMEOUT_MASK					0x7FFFU
+/* WDOG_DISABLE1 Register 32bit (-/W) */
+#define U300_WDOG_D1R							0x08
+#define U300_WDOG_D1R_DISABLE1_DISABLE_TIMER				0x2BADU
+/* WDOG_DISABLE2 Register 32bit (R/W) */
+#define U300_WDOG_D2R							0x0C
+#define U300_WDOG_D2R_DISABLE2_DISABLE_TIMER				0xCAFEU
+#define U300_WDOG_D2R_DISABLE_STATUS_DISABLED				0xDABEU
+#define U300_WDOG_D2R_DISABLE_STATUS_ENABLED				0x0000U
+/* WDOG_STATUS Register 32bit (R/W) */
+#define U300_WDOG_SR							0x10
+#define U300_WDOG_SR_STATUS_TIMED_OUT					0xCFE8U
+#define U300_WDOG_SR_STATUS_NORMAL					0x0000U
+#define U300_WDOG_SR_RESET_STATUS_RESET					0xE8B4U
+/* WDOG_COUNT Register 32bit (R/-) */
+#define U300_WDOG_CR							0x14
+#define U300_WDOG_CR_VALID_IND						0x8000U
+#define U300_WDOG_CR_VALID_STABLE					0x0000U
+#define U300_WDOG_CR_COUNT_VALUE_MASK					0x7FFFU
+/* WDOG_JTAGOVR Register 32bit (R/W) */
+#define U300_WDOG_JOR							0x18
+#define U300_WDOG_JOR_JTAG_MODE_IND					0x0002U
+#define U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE				0x0001U
+/* WDOG_RESTART Register 32bit (-/W) */
+#define U300_WDOG_RR							0x1C
+#define U300_WDOG_RR_RESTART_VALUE_RESUME				0xACEDU
+/* WDOG_IRQ_EVENT Register 32bit (R/W) */
+#define U300_WDOG_IER							0x20
+#define U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND				0x0001U
+#define U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE				0x0001U
+/* WDOG_IRQ_MASK Register 32bit (R/W) */
+#define U300_WDOG_IMR							0x24
+#define U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE				0x0001U
+/* WDOG_IRQ_FORCE Register 32bit (R/W) */
+#define U300_WDOG_IFR							0x28
+#define U300_WDOG_IFR_WILL_BARK_IRQ_FORCE_ENABLE			0x0001U
+
+/* Default timeout in seconds = 1 minute */
+static int margin = 60;
+static resource_size_t phybase;
+static resource_size_t physize;
+static int irq;
+static void __iomem *virtbase;
+static unsigned long coh901327_users;
+static unsigned long boot_status;
+static u16 wdogenablestore;
+static u16 irqmaskstore;
+static struct device *parent;
+
+/*
+ * The watchdog block is of course always clocked, the
+ * clk_enable()/clk_disable() calls are mainly for performing reference
+ * counting higher up in the clock hierarchy.
+ */
+static struct clk *clk;
+
+/*
+ * Enabling and disabling functions.
+ */
+static void coh901327_enable(u16 timeout)
+{
+	u16 val;
+
+	clk_enable(clk);
+	/* Restart timer if it is disabled */
+	val = readw(virtbase + U300_WDOG_D2R);
+	if (val == U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
+		writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
+		       virtbase + U300_WDOG_RR);
+	/* Acknowledge any pending interrupt so it doesn't just fire off */
+	writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
+	       virtbase + U300_WDOG_IER);
+	/* Enable the watchdog interrupt */
+	writew(U300_WDOG_IMR_WILL_BARK_IRQ_ENABLE, virtbase + U300_WDOG_IMR);
+	/* Activate the watchdog timer */
+	writew(timeout, virtbase + U300_WDOG_TR);
+	/* Start the watchdog timer */
+	writew(U300_WDOG_FR_FEED_RESTART_TIMER, virtbase + U300_WDOG_FR);
+	/*
+	 * Extra read so that this change propagate in the watchdog.
+	 */
+	(void) readw(virtbase + U300_WDOG_CR);
+	val = readw(virtbase + U300_WDOG_D2R);
+	clk_disable(clk);
+	if (val != U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
+		dev_err(parent,
+			"%s(): watchdog not enabled! D2R value %04x\n",
+			__func__, val);
+}
+
+static void coh901327_disable(void)
+{
+	u16 val;
+
+	clk_enable(clk);
+	/* Disable the watchdog interrupt if it is active */
+	writew(0x0000U, virtbase + U300_WDOG_IMR);
+	/* If the watchdog is currently enabled, attempt to disable it */
+	val = readw(virtbase + U300_WDOG_D2R);
+	if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED) {
+		writew(U300_WDOG_D1R_DISABLE1_DISABLE_TIMER,
+		       virtbase + U300_WDOG_D1R);
+		writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
+		       virtbase + U300_WDOG_D2R);
+		/* Write this twice (else problems occur) */
+		writew(U300_WDOG_D2R_DISABLE2_DISABLE_TIMER,
+		       virtbase + U300_WDOG_D2R);
+	}
+	val = readw(virtbase + U300_WDOG_D2R);
+	clk_disable(clk);
+	if (val != U300_WDOG_D2R_DISABLE_STATUS_DISABLED)
+		dev_err(parent,
+			"%s(): watchdog not disabled! D2R value %04x\n",
+			__func__, val);
+}
+
+static void coh901327_start(void)
+{
+	coh901327_enable(margin * 100);
+}
+
+static void coh901327_keepalive(void)
+{
+	clk_enable(clk);
+	/* Feed the watchdog */
+	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
+	       virtbase + U300_WDOG_FR);
+	clk_disable(clk);
+}
+
+static int coh901327_settimeout(int time)
+{
+	/*
+	 * Max margin is 327 since the 10ms
+	 * timeout register is max
+	 * 0x7FFF = 327670ms ~= 327s.
+	 */
+	if (time <= 0 || time > 327)
+		return -EINVAL;
+
+	margin = time;
+	clk_enable(clk);
+	/* Set new timeout value */
+	writew(margin * 100, virtbase + U300_WDOG_TR);
+	/* Feed the dog */
+	writew(U300_WDOG_FR_FEED_RESTART_TIMER,
+	       virtbase + U300_WDOG_FR);
+	clk_disable(clk);
+	return 0;
+}
+
+/*
+ * This interrupt occurs 10 ms before the watchdog WILL bark.
+ */
+static irqreturn_t coh901327_interrupt(int irq, void *data)
+{
+	u16 val;
+
+	/*
+	 * Ack IRQ? If this occurs we're FUBAR anyway, so
+	 * just acknowledge, disable the interrupt and await the imminent end.
+	 * If you at some point need a host of callbacks to be called
+	 * when the system is about to watchdog-reset, add them here!
+	 *
+	 * NOTE: on future versions of this IP-block, it will be possible
+	 * to prevent a watchdog reset by feeding the watchdog at this
+	 * point.
+	 */
+	clk_enable(clk);
+	val = readw(virtbase + U300_WDOG_IER);
+	if (val == U300_WDOG_IER_WILL_BARK_IRQ_EVENT_IND)
+		writew(U300_WDOG_IER_WILL_BARK_IRQ_ACK_ENABLE,
+		       virtbase + U300_WDOG_IER);
+	writew(0x0000U, virtbase + U300_WDOG_IMR);
+	clk_disable(clk);
+	dev_crit(parent, "watchdog is barking!\n");
+	return IRQ_HANDLED;
+}
+
+/*
+ * Allow only one user (daemon) to open the watchdog
+ */
+static int coh901327_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(1, &coh901327_users))
+		return -EBUSY;
+	coh901327_start();
+	return nonseekable_open(inode, file);
+}
+
+static int coh901327_release(struct inode *inode, struct file *file)
+{
+	clear_bit(1, &coh901327_users);
+	coh901327_disable();
+	return 0;
+}
+
+static ssize_t coh901327_write(struct file *file, const char __user *data,
+			       size_t len, loff_t *ppos)
+{
+	if (len)
+		coh901327_keepalive();
+	return len;
+}
+
+static long coh901327_ioctl(struct file *file, unsigned int cmd,
+			    unsigned long arg)
+{
+	int ret = -ENOTTY;
+	u16 val;
+	int time;
+	int new_options;
+	union {
+		struct watchdog_info __user *ident;
+		int __user *i;
+	} uarg;
+	static struct watchdog_info ident = {
+		.options		= WDIOF_CARDRESET |
+					  WDIOF_SETTIMEOUT |
+					  WDIOF_KEEPALIVEPING,
+		.identity		= "COH 901 327 Watchdog",
+		.firmware_version	= 1,
+	};
+	uarg.i = (int __user *)arg;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		ret = copy_to_user(uarg.ident, &ident,
+				   sizeof(ident)) ? -EFAULT : 0;
+		break;
+
+	case WDIOC_GETSTATUS:
+		ret = put_user(0, uarg.i);
+		break;
+
+	case WDIOC_GETBOOTSTATUS:
+		ret = put_user(boot_status, uarg.i);
+		break;
+
+	case WDIOC_SETOPTIONS:
+		ret = get_user(new_options, uarg.i);
+		if (ret)
+			break;
+		if (new_options & WDIOS_DISABLECARD)
+			coh901327_disable();
+		if (new_options & WDIOS_ENABLECARD)
+			coh901327_start();
+		ret = 0;
+		break;
+
+	case WDIOC_KEEPALIVE:
+		coh901327_keepalive();
+		ret = 0;
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		ret = get_user(time, uarg.i);
+		if (ret)
+			break;
+
+		ret = coh901327_settimeout(time);
+		if (ret)
+			break;
+		/* Then fall through to return set value */
+
+	case WDIOC_GETTIMEOUT:
+		ret = put_user(margin, uarg.i);
+		break;
+
+	case WDIOC_GETTIMELEFT:
+		clk_enable(clk);
+		/* Read repeatedly until the value is stable! */
+		val = readw(virtbase + U300_WDOG_CR);
+		while (val & U300_WDOG_CR_VALID_IND)
+			val = readw(virtbase + U300_WDOG_CR);
+		val &= U300_WDOG_CR_COUNT_VALUE_MASK;
+		clk_disable(clk);
+		if (val != 0)
+			val /= 100;
+		ret = put_user(val, uarg.i);
+		break;
+	}
+	return ret;
+}
+
+static const struct file_operations coh901327_fops = {
+	.owner		= THIS_MODULE,
+	.llseek		= no_llseek,
+	.write		= coh901327_write,
+	.unlocked_ioctl	= coh901327_ioctl,
+	.open		= coh901327_open,
+	.release	= coh901327_release,
+};
+
+static struct miscdevice coh901327_miscdev = {
+	.minor		= WATCHDOG_MINOR,
+	.name		= "watchdog",
+	.fops		= &coh901327_fops,
+};
+
+static int __exit coh901327_remove(struct platform_device *pdev)
+{
+	misc_deregister(&coh901327_miscdev);
+	coh901327_disable();
+	free_irq(irq, pdev);
+	clk_put(clk);
+	iounmap(virtbase);
+	release_mem_region(phybase, physize);
+	return 0;
+}
+
+
+static int __init coh901327_probe(struct platform_device *pdev)
+{
+	int ret;
+	u16 val;
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENOENT;
+
+	parent = &pdev->dev;
+	physize = resource_size(res);
+	phybase = res->start;
+
+	if (request_mem_region(phybase, physize, DRV_NAME) == NULL) {
+		ret = -EBUSY;
+		goto out;
+	}
+
+	virtbase = ioremap(phybase, physize);
+	if (!virtbase) {
+		ret = -ENOMEM;
+		goto out_no_remap;
+	}
+
+	clk = clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		ret = PTR_ERR(clk);
+		dev_err(&pdev->dev, "could not get clock\n");
+		goto out_no_clk;
+	}
+	ret = clk_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "could not enable clock\n");
+		goto out_no_clk_enable;
+	}
+
+	val = readw(virtbase + U300_WDOG_SR);
+	switch (val) {
+	case U300_WDOG_SR_STATUS_TIMED_OUT:
+		dev_info(&pdev->dev,
+			"watchdog timed out since last chip reset!\n");
+		boot_status = WDIOF_CARDRESET;
+		/* Status will be cleared below */
+		break;
+	case U300_WDOG_SR_STATUS_NORMAL:
+		dev_info(&pdev->dev,
+			"in normal status, no timeouts have occurred.\n");
+		break;
+	default:
+		dev_info(&pdev->dev,
+			"contains an illegal status code (%08x)\n", val);
+		break;
+	}
+
+	val = readw(virtbase + U300_WDOG_D2R);
+	switch (val) {
+	case U300_WDOG_D2R_DISABLE_STATUS_DISABLED:
+		dev_info(&pdev->dev, "currently disabled.\n");
+		break;
+	case U300_WDOG_D2R_DISABLE_STATUS_ENABLED:
+		dev_info(&pdev->dev,
+			 "currently enabled! (disabling it now)\n");
+		coh901327_disable();
+		break;
+	default:
+		dev_err(&pdev->dev,
+			"contains an illegal enable/disable code (%08x)\n",
+			val);
+		break;
+	}
+
+	/* Reset the watchdog */
+	writew(U300_WDOG_SR_RESET_STATUS_RESET, virtbase + U300_WDOG_SR);
+
+	irq = platform_get_irq(pdev, 0);
+	if (request_irq(irq, coh901327_interrupt, IRQF_DISABLED,
+			DRV_NAME " Bark", pdev)) {
+		ret = -EIO;
+		goto out_no_irq;
+	}
+
+	clk_disable(clk);
+
+	ret = misc_register(&coh901327_miscdev);
+	if (ret == 0)
+		dev_info(&pdev->dev,
+			 "initialized. timer margin=%d sec\n", margin);
+	else
+		goto out_no_wdog;
+
+	return 0;
+
+out_no_wdog:
+	free_irq(irq, pdev);
+out_no_irq:
+	clk_disable(clk);
+out_no_clk_enable:
+	clk_put(clk);
+out_no_clk:
+	iounmap(virtbase);
+out_no_remap:
+	release_mem_region(phybase, SZ_4K);
+out:
+	return ret;
+}
+
+#ifdef CONFIG_PM
+static int coh901327_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	irqmaskstore = readw(virtbase + U300_WDOG_IMR) & 0x0001U;
+	wdogenablestore = readw(virtbase + U300_WDOG_D2R);
+	/* If watchdog is on, disable it here and now */
+	if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED)
+		coh901327_disable();
+	return 0;
+}
+
+static int coh901327_resume(struct platform_device *pdev)
+{
+	/* Restore the watchdog interrupt */
+	writew(irqmaskstore, virtbase + U300_WDOG_IMR);
+	if (wdogenablestore == U300_WDOG_D2R_DISABLE_STATUS_ENABLED) {
+		/* Restart the watchdog timer */
+		writew(U300_WDOG_RR_RESTART_VALUE_RESUME,
+		       virtbase + U300_WDOG_RR);
+		writew(U300_WDOG_FR_FEED_RESTART_TIMER,
+		       virtbase + U300_WDOG_FR);
+	}
+	return 0;
+}
+#else
+#define coh901327_suspend NULL
+#define coh901327_resume  NULL
+#endif
+
+/*
+ * Mistreating the watchdog is the only way to perform a software reset of the
+ * system on EMP platforms. So we implement this and export a symbol for it.
+ */
+void coh901327_watchdog_reset(void)
+{
+	/* Enable even if on JTAG too */
+	writew(U300_WDOG_JOR_JTAG_WATCHDOG_ENABLE,
+	       virtbase + U300_WDOG_JOR);
+	/*
+	 * Timeout = 5s, we have to wait for the watchdog reset to
+	 * actually take place: the watchdog will be reloaded with the
+	 * default value immediately, so we HAVE to reboot and get back
+	 * into the kernel in 30s, or the device will reboot again!
+	 * The boot loader will typically deactivate the watchdog, so we
+	 * need time enough for the boot loader to get to the point of
+	 * deactivating the watchdog before it is shut down by it.
+	 *
+	 * NOTE: on future versions of the watchdog, this restriction is
+	 * gone: the watchdog will be reloaded with a defaul value (1 min)
+	 * instead of last value, and you can conveniently set the watchdog
+	 * timeout to 10ms (value = 1) without any problems.
+	 */
+	coh901327_enable(500);
+	/* Return and await doom */
+}
+
+static struct platform_driver coh901327_driver = {
+	.driver = {
+		.owner	= THIS_MODULE,
+		.name	= "coh901327_wdog",
+	},
+	.remove		= __exit_p(coh901327_remove),
+	.suspend	= coh901327_suspend,
+	.resume		= coh901327_resume,
+};
+
+static int __init coh901327_init(void)
+{
+	return platform_driver_probe(&coh901327_driver, coh901327_probe);
+}
+module_init(coh901327_init);
+
+static void __exit coh901327_exit(void)
+{
+	platform_driver_unregister(&coh901327_driver);
+}
+module_exit(coh901327_exit);
+
+MODULE_AUTHOR("Linus Walleij <linus.walleij@stericsson.com>");
+MODULE_DESCRIPTION("COH 901 327 Watchdog");
+
+module_param(margin, int, 0);
+MODULE_PARM_DESC(margin, "Watchdog margin in seconds (default 60s)");
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);