/*
* Watchdog Device Driver for Xilinx axi/xps_timebase_wdt
*
* (C) Copyright 2013 - 2014 Xilinx, Inc.
* (C) Copyright 2011 (Alejandro Cabrera <aldaya@gmail.com>)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/err.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/ioport.h>
#include <linux/watchdog.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_address.h>
/* Register offsets for the Wdt device */
#define XWT_TWCSR0_OFFSET 0x0 /* Control/Status Register0 */
#define XWT_TWCSR1_OFFSET 0x4 /* Control/Status Register1 */
#define XWT_TBR_OFFSET 0x8 /* Timebase Register Offset */
/* Control/Status Register Masks */
#define XWT_CSR0_WRS_MASK 0x00000008 /* Reset status */
#define XWT_CSR0_WDS_MASK 0x00000004 /* Timer state */
#define XWT_CSR0_EWDT1_MASK 0x00000002 /* Enable bit 1 */
/* Control/Status Register 0/1 bits */
#define XWT_CSRX_EWDT2_MASK 0x00000001 /* Enable bit 2 */
/* SelfTest constants */
#define XWT_MAX_SELFTEST_LOOP_COUNT 0x00010000
#define XWT_TIMER_FAILED 0xFFFFFFFF
#define WATCHDOG_NAME "Xilinx Watchdog"
#define PFX WATCHDOG_NAME ": "
struct xwdt_device {
void __iomem *base;
u32 wdt_interval;
};
static struct xwdt_device xdev;
static u32 timeout;
static DEFINE_SPINLOCK(spinlock);
static int xilinx_wdt_start(struct watchdog_device *wdd)
{
u32 control_status_reg;
spin_lock(&spinlock);
/* Clean previous status and enable the watchdog timer */
control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
iowrite32((control_status_reg | XWT_CSR0_EWDT1_MASK),
xdev.base + XWT_TWCSR0_OFFSET);
iowrite32(XWT_CSRX_EWDT2_MASK, xdev.base + XWT_TWCSR1_OFFSET);
spin_unlock(&spinlock);
return 0;
}
static int xilinx_wdt_stop(struct watchdog_device *wdd)
{
u32 control_status_reg;
spin_lock(&spinlock);
control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
iowrite32((control_status_reg & ~XWT_CSR0_EWDT1_MASK),
xdev.base + XWT_TWCSR0_OFFSET);
iowrite32(0, xdev.base + XWT_TWCSR1_OFFSET);
spin_unlock(&spinlock);
pr_info("Stopped!\n");
return 0;
}
static int xilinx_wdt_keepalive(struct watchdog_device *wdd)
{
u32 control_status_reg;
spin_lock(&spinlock);
control_status_reg = ioread32(xdev.base + XWT_TWCSR0_OFFSET);
control_status_reg |= (XWT_CSR0_WRS_MASK | XWT_CSR0_WDS_MASK);
iowrite32(control_status_reg, xdev.base + XWT_TWCSR0_OFFSET);
spin_unlock(&spinlock);
return 0;
}
static const struct watchdog_info xilinx_wdt_ident = {
.options = WDIOF_MAGICCLOSE |
WDIOF_KEEPALIVEPING,
.firmware_version = 1,
.identity = WATCHDOG_NAME,
};
static const struct watchdog_ops xilinx_wdt_ops = {
.owner = THIS_MODULE,
.start = xilinx_wdt_start,
.stop = xilinx_wdt_stop,
.ping = xilinx_wdt_keepalive,
};
static struct watchdog_device xilinx_wdt_wdd = {
.info = &xilinx_wdt_ident,
.ops = &xilinx_wdt_ops,
};
static u32 xwdt_selftest(void)
{
int i;
u32 timer_value1;
u32 timer_value2;
spin_lock(&spinlock);
timer_value1 = ioread32(xdev.base + XWT_TBR_OFFSET);
timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
for (i = 0;
((i <= XWT_MAX_SELFTEST_LOOP_COUNT) &&
(timer_value2 == timer_value1)); i++) {
timer_value2 = ioread32(xdev.base + XWT_TBR_OFFSET);
}
spin_unlock(&spinlock);
if (timer_value2 != timer_value1)
return ~XWT_TIMER_FAILED;
else
return XWT_TIMER_FAILED;
}
static int xwdt_probe(struct platform_device *pdev)
{
int rc;
u32 *tmptr;
u32 *pfreq;
struct resource *res;
bool no_timeout = false;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
xdev.base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(xdev.base))
return PTR_ERR(xdev.base);
pfreq = (u32 *)of_get_property(pdev->dev.of_node,
"clock-frequency", NULL);
if (pfreq == NULL) {
pr_warn("The watchdog clock frequency cannot be obtained!\n");
no_timeout = true;
}
tmptr = (u32 *)of_get_property(pdev->dev.of_node,
"xlnx,wdt-interval", NULL);
if (tmptr == NULL) {
pr_warn("Parameter \"xlnx,wdt-interval\" not found in device tree!\n");
no_timeout = true;
} else {
xdev.wdt_interval = *tmptr;
}
tmptr = (u32 *)of_get_property(pdev->dev.of_node,
"xlnx,wdt-enable-once", NULL);
if (tmptr == NULL) {
pr_warn("Parameter \"xlnx,wdt-enable-once\" not found in device tree!\n");
watchdog_set_nowayout(&xilinx_wdt_wdd, true);
}
/*
* Twice of the 2^wdt_interval / freq because the first wdt overflow is
* ignored (interrupt), reset is only generated at second wdt overflow
*/
if (!no_timeout)
timeout = 2 * ((1<<xdev.wdt_interval) / *pfreq);
rc = xwdt_selftest();
if (rc == XWT_TIMER_FAILED) {
pr_err("SelfTest routine error!\n");
return rc;
}
rc = watchdog_register_device(&xilinx_wdt_wdd);
if (rc) {
pr_err("cannot register watchdog (err=%d)\n", rc);
return rc;
}
dev_info(&pdev->dev, "Xilinx Watchdog Timer at %p with timeout %ds\n",
xdev.base, timeout);
return 0;
}
static int xwdt_remove(struct platform_device *dev)
{
watchdog_unregister_device(&xilinx_wdt_wdd);
return 0;
}
/* Match table for of_platform binding */
static struct of_device_id xwdt_of_match[] = {
{ .compatible = "xlnx,xps-timebase-wdt-1.00.a", },
{ .compatible = "xlnx,xps-timebase-wdt-1.01.a", },
{},
};
MODULE_DEVICE_TABLE(of, xwdt_of_match);
static struct platform_driver xwdt_driver = {
.probe = xwdt_probe,
.remove = xwdt_remove,
.driver = {
.owner = THIS_MODULE,
.name = WATCHDOG_NAME,
.of_match_table = xwdt_of_match,
},
};
module_platform_driver(xwdt_driver);
MODULE_AUTHOR("Alejandro Cabrera <aldaya@gmail.com>");
MODULE_DESCRIPTION("Xilinx Watchdog driver");
MODULE_LICENSE("GPL v2");
