[PATCH v3 1/2] drivers: watchdog: add a driver to support SAMA5D4 watchdog timer

Yang, Wenyou
2015-08-06T02:14:00Z

Hi Guenter,

Thank you for your review.

> -----Original Message-----
> From: Guenter Roeck [mailto:linux at roeck-us.net]
> Sent: 2015?8?5? 23:05
> To: Yang, Wenyou; wim at iguana.be; robh+dt at kernel.org; pawel.moll at arm.com;
> mark.rutland at arm.com; ijc+devicetree at hellion.org.uk; galak at codeaurora.org
> Cc: sylvain.rochet at finsecur.com; Ferre, Nicolas; boris.brezillon at free-
> electrons.com; devicetree at vger.kernel.org; linux-kernel at vger.kernel.org; linux-
> watchdog at vger.kernel.org; linux-arm-kernel at lists.infradead.org
> Subject: Re: [PATCH v3 1/2] drivers: watchdog: add a driver to support SAMA5D4
> watchdog timer
>
> On 08/05/2015 01:57 AM, Wenyou Yang wrote:
> >>From SAMA5D4, the watchdog timer is upgrated with a new feature,
> > which is describled as in the datasheet, "WDT_MR can be written until
> > a LOCKMR command is issued in WDT_CR".
> > That is to say, as long as the bootstrap and u-boot don't issue a
> > LOCKMR command, WDT_MR can be written more than once in the driver.
> >
> > So the SAMA5D4 watchdog driver's implementation is different from the
> > at91sam9260 watchdog driver implemented in file at91sam9_wdt.c.
> > The user application open the device file to enable the watchdog timer
> > hardware, and close to disable it, and set the watchdog timer timeout
> > by seting WDV and WDD fields of WDT_MR register, and ping the watchdog
> > by issuing WDRSTT command to WDT_CR register with hard-coded key.
> >
> > Signed-off-by: Wenyou Yang <wenyou.yang@atmel.com>
> > ---
> > drivers/watchdog/Kconfig | 9 ++
> > drivers/watchdog/Makefile | 1 +
> > drivers/watchdog/at91_sama5d4_wdt.c | 279
> +++++++++++++++++++++++++++++++++++
> > drivers/watchdog/at91sam9_wdt.h | 2 +
> > 4 files changed, 291 insertions(+)
> > create mode 100644 drivers/watchdog/at91_sama5d4_wdt.c
> >
> > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig index
> > e5e7c55..4ce8346 100644
> > --- a/drivers/watchdog/Kconfig
> > +++ b/drivers/watchdog/Kconfig
> > @@ -152,6 +152,15 @@ config ARM_SP805_WATCHDOG
> > ARM Primecell SP805 Watchdog timer. This will reboot your system
> when
> > the timeout is reached.
> >
> > +config AT91_SAMA5D4_WATCHDOG
>
> Looking into the chip ordering documentation. The chip goes by ATSAMA5D4,
> while the other chips go by AT91SAM9xxx.
>
> So I think ATSAMA5D4 would be better (same for the driver name).
Use SAMA5D4 directly, the chip name.

>
> Couple of additional nitpicks below.
I will change it in the next version, thanks.

>
> Thanks,
> Guenter
>
> > + tristate "Atmel SAMA5D4 Watchdog Timer"
> > + depends on ARCH_AT91
> > + select WATCHDOG_CORE
> > + help
> > + Atmel SAMA5D4 watchdog timer is embedded into SAMA5D4 chips.
> > + Its Watchdog Timer Mode Register can be written more than once.
> > + This will reboot your system when the timeout is reached.
> > +
> > config AT91RM9200_WATCHDOG
> > tristate "AT91RM9200 watchdog"
> > depends on SOC_AT91RM9200 && MFD_SYSCON diff --git
> > a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile index
> > 5c19294..c57569c 100644
> > --- a/drivers/watchdog/Makefile
> > +++ b/drivers/watchdog/Makefile
> > @@ -30,6 +30,7 @@ obj-$(CONFIG_USBPCWATCHDOG) += pcwd_usb.o
> >
> > # ARM Architecture
> > obj-$(CONFIG_ARM_SP805_WATCHDOG) += sp805_wdt.o
> > +obj-$(CONFIG_AT91_SAMA5D4_WATCHDOG) += at91_sama5d4_wdt.o
> > obj-$(CONFIG_AT91RM9200_WATCHDOG) += at91rm9200_wdt.o
> > obj-$(CONFIG_AT91SAM9X_WATCHDOG) += at91sam9_wdt.o
> > obj-$(CONFIG_CADENCE_WATCHDOG) += cadence_wdt.o diff --git
> > a/drivers/watchdog/at91_sama5d4_wdt.c
> > b/drivers/watchdog/at91_sama5d4_wdt.c
> > new file mode 100644
> > index 0000000..f2e1995
> > --- /dev/null
> > +++ b/drivers/watchdog/at91_sama5d4_wdt.c
> > @@ -0,0 +1,279 @@
> > +/*
> > + * Driver for Atmel SAMA5D4 Watchdog Timer
> > + *
> > + * Copyright (C) 2015 Atmel Corporation
> > + *
> > + * Licensed under GPLv2.
> > + */
> > +
> > +#include <linux/interrupt.h>
> > +#include <linux/io.h>
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/of_irq.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/reboot.h>
> > +#include <linux/watchdog.h>
> > +
> > +#include "at91sam9_wdt.h"
> > +
> > +/* minimum and maximum watchdog timeout, in seconds */
> > +#define MIN_WDT_TIMEOUT 1
> > +#define MAX_WDT_TIMEOUT 16
> > +#define WDT_DEFAULT_TIMEOUT MAX_WDT_TIMEOUT
> > +
> > +#define WDT_SEC2TICKS(s) ((s) ? (((s) << 8) - 1) : 0)
> > +
> > +struct atmel_wdt {
>
> If you don't mind, please use "sama5d4" as prefix here and for function names.
>
> > + struct watchdog_device wdd;
> > + void __iomem *reg_base;
> > + u32 config;
> > +};
> > +
> > +static int wdt_timeout = WDT_DEFAULT_TIMEOUT; static bool nowayout =
> > +WATCHDOG_NOWAYOUT;
> > +
> > +module_param(wdt_timeout, int, 0);
> > +MODULE_PARM_DESC(wdt_timeout,
> > + "Watchdog wdt_timeout in seconds. (default = "
> > + __MODULE_STRING(WDT_DEFAULT_TIMEOUT) ")");
> > +
> > +module_param(nowayout, bool, 0);
> > +MODULE_PARM_DESC(nowayout,
> > + "Watchdog cannot be stopped once started (default="
> > + __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
> > +
> > +#define wdt_read(wdt, field) \
> > + readl_relaxed((wdt)->reg_base + (field))
> > +
> > +#define wdt_write(wtd, field, val) \
> > + writel_relaxed((val), (wdt)->reg_base + (field))
> > +
> > +static int atmel_wdt_start(struct watchdog_device *wdd) {
> > + struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > + u32 reg;
> > +
> > + reg = wdt_read(wdt, AT91_WDT_MR);
> > + reg &= ~AT91_WDT_WDDIS;
> > + wdt_write(wdt, AT91_WDT_MR, reg);
> > +
> > + return 0;
> > +}
> > +
> > +static int atmel_wdt_stop(struct watchdog_device *wdd) {
> > + struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > + u32 reg;
> > +
> > + reg = wdt_read(wdt, AT91_WDT_MR);
> > + reg |= AT91_WDT_WDDIS;
> > + wdt_write(wdt, AT91_WDT_MR, reg);
> > +
> > + return 0;
> > +}
> > +
> > +static int atmel_wdt_ping(struct watchdog_device *wdd) {
> > + struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > +
> > + wdt_write(wdt, AT91_WDT_CR, AT91_WDT_KEY |
> AT91_WDT_WDRSTT);
> > +
> > + return 0;
> > +}
> > +
> > +static int atmel_wdt_set_timeout(struct watchdog_device *wdd,
> > + unsigned int timeout)
> > +{
> > + struct atmel_wdt *wdt = watchdog_get_drvdata(wdd);
> > + u32 value = WDT_SEC2TICKS(timeout);
> > + u32 reg;
> > +
> > + reg = wdt_read(wdt, AT91_WDT_MR);
> > + reg &= ~AT91_WDT_WDV;
> > + reg &= ~AT91_WDT_WDD;
> > + reg |= AT91_WDT_SET_WDV(value);
> > + reg |= AT91_WDT_SET_WDD(value);
> > + wdt_write(wdt, AT91_WDT_MR, reg);
> > +
> > + wdd->timeout = timeout;
> > +
> > + return 0;
> > +}
> > +
> > +static const struct watchdog_info atmel_wdt_info = {
> > + .options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
> WDIOF_KEEPALIVEPING,
> > + .firmware_version = 0,
>
> Unnecessary initialization.
>
> > + .identity = "Atmel SAMA5D4 Watchdog", };
> > +
> > +static struct watchdog_ops atmel_wdt_ops = {
> > + .owner = THIS_MODULE,
> > + .start = atmel_wdt_start,
> > + .stop = atmel_wdt_stop,
> > + .ping = atmel_wdt_ping,
> > + .set_timeout = atmel_wdt_set_timeout, };
> > +
> > +static irqreturn_t atmel_wdt_irq_handler(int irq, void *dev_id) {
> > + struct atmel_wdt *wdt = platform_get_drvdata(dev_id);
> > +
> > + if (wdt_read(wdt, AT91_WDT_SR)) {
> > + pr_crit("Atmel Watchdog Software Reset\n");
> > + emergency_restart();
> > + pr_crit("Reboot didn't ?????\n");
> > + }
> > +
> > + return IRQ_HANDLED;
> > +}
> > +
> > +static int of_atmel_wdt_init(struct device_node *np, struct atmel_wdt
> > +*wdt) {
> > + const char *tmp;
> > +
> > + wdt->config = AT91_WDT_WDDIS;
> > +
> > + if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
> > + !strcmp(tmp, "software"))
> > + wdt->config |= AT91_WDT_WDFIEN;
> > + else
> > + wdt->config |= AT91_WDT_WDRSTEN;
> > +
> > + if (of_property_read_bool(np, "atmel,idle-halt"))
> > + wdt->config |= AT91_WDT_WDIDLEHLT;
> > +
> > + if (of_property_read_bool(np, "atmel,dbg-halt"))
> > + wdt->config |= AT91_WDT_WDDBGHLT;
> > +
> > + return 0;
> > +}
> > +
> > +static int atmel_wdt_init(struct atmel_wdt *wdt) {
> > + struct watchdog_device *wdd = &wdt->wdd;
> > + u32 value = WDT_SEC2TICKS(wdd->timeout);
> > + u32 reg;
> > +
> > + /*
> > + * Because the fields WDV and WDD must not be modified when the
> WDDIS
> > + * bit is set, so clear the WDDIS bit before writing the WDT_MR.
> > + */
> > + reg = wdt_read(wdt, AT91_WDT_MR);
> > + reg &= ~AT91_WDT_WDDIS;
> > + wdt_write(wdt, AT91_WDT_MR, reg);
> > +
> > + reg = wdt->config;
> > + reg |= AT91_WDT_SET_WDD(value);
> > + reg |= AT91_WDT_SET_WDV(value);
> > +
> > + wdt_write(wdt, AT91_WDT_MR, reg);
> > +
> > + return 0;
> > +}
> > +
> > +static int atmel_wdt_probe(struct platform_device *pdev) {
> > + struct watchdog_device *wdd;
> > + struct atmel_wdt *wdt;
> > + struct resource *res;
> > + void __iomem *regs;
> > + int ret, irq = -1;
>
> Might as well use irq = 0 here for consistency.
>
> > +
> > + wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
> > + if (!wdt)
> > + return -ENOMEM;
> > +
> > + wdd = &wdt->wdd;
> > + wdd->timeout = wdt_timeout;
> > + wdd->info = &atmel_wdt_info;
> > + wdd->ops = &atmel_wdt_ops;
> > + wdd->min_timeout = MIN_WDT_TIMEOUT;
> > + wdd->max_timeout = MAX_WDT_TIMEOUT;
> > +
> > + watchdog_set_drvdata(wdd, wdt);
> > +
> > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> > + regs = devm_ioremap_resource(&pdev->dev, res);
> > + if (IS_ERR(regs))
> > + return PTR_ERR(regs);
> > +
> > + wdt->reg_base = regs;
> > +
> > + if (pdev->dev.of_node) {
> > + irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
> > + if (!irq)
> > + dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
> > +
> > + ret = of_atmel_wdt_init(pdev->dev.of_node, wdt);
> > + if (ret)
> > + return ret;
> > + }
> > +
> > + if ((wdt->config & AT91_WDT_WDFIEN) && irq > 0) {
>
> ... then you can check " ... && irq" here.
>
> > + ret = devm_request_irq(&pdev->dev, irq, atmel_wdt_irq_handler,
> > + 0, pdev->name, pdev);
> > + if (ret) {
> > + dev_err(&pdev->dev,
> > + "cannot register interrupt handler\n");
> > + return ret;
> > + }
> > + }
> > +
> > + ret = watchdog_init_timeout(wdd, wdt_timeout, &pdev->dev);
> > + if (ret) {
> > + dev_err(&pdev->dev, "unable to set timeout value\n");
> > + return ret;
> > + }
> > +
> > + ret = atmel_wdt_init(wdt);
> > + if (ret)
> > + return ret;
> > +
> > + watchdog_set_nowayout(wdd, nowayout);
> > +
> > + ret = watchdog_register_device(wdd);
> > + if (ret) {
> > + dev_err(&pdev->dev, "failed to register watchdog device\n");
> > + return ret;
> > + }
> > +
> > + platform_set_drvdata(pdev, wdt);
> > +
> > + dev_info(&pdev->dev, "initialized (timeout = %d sec, nowayout = %d)\n",
> > + wdt_timeout, nowayout);
> > +
> > + return 0;
> > +}
> > +
> > +static int atmel_wdt_remove(struct platform_device *pdev) {
> > + struct atmel_wdt *wdt = platform_get_drvdata(pdev);
> > +
> > + atmel_wdt_stop(&wdt->wdd);
> > +
> > + watchdog_unregister_device(&wdt->wdd);
> > +
> > + return 0;
> > +}
> > +
> > +static const struct of_device_id atmel_wdt_of_match[] = {
> > + { .compatible = "atmel,sama5d4-wdt", },
> > + { },
> > +};
> > +MODULE_DEVICE_TABLE(of, atmel_wdt_of_match);
> > +
> > +static struct platform_driver atmel_wdt_driver = {
> > + .probe = atmel_wdt_probe,
> > + .remove = atmel_wdt_remove,
> > + .driver = {
> > + .name = "sama5d4 wdt",
> > + .of_match_table = atmel_wdt_of_match,
> > + },
> > +};
> > +module_platform_driver(atmel_wdt_driver);
> > +
> > +MODULE_AUTHOR("Atmel Corporation");
> > +MODULE_DESCRIPTION("Atmel SAMA5D4 Watchdog Timer driver");
> > +MODULE_LICENSE("GPL v2");
> > diff --git a/drivers/watchdog/at91sam9_wdt.h
> > b/drivers/watchdog/at91sam9_wdt.h index c6fbb2e6..b79a83b 100644
> > --- a/drivers/watchdog/at91sam9_wdt.h
> > +++ b/drivers/watchdog/at91sam9_wdt.h
> > @@ -22,11 +22,13 @@
> >
> > #define AT91_WDT_MR 0x04 /* Watchdog
> Mode Register */
> > #define AT91_WDT_WDV (0xfff << 0) /*
> Counter Value */
> > +#define AT91_WDT_SET_WDV(x) ((x) &
> AT91_WDT_WDV)
> > #define AT91_WDT_WDFIEN (1 << 12) /*
> Fault Interrupt Enable */
> > #define AT91_WDT_WDRSTEN (1 << 13) /*
> Reset Processor */
> > #define AT91_WDT_WDRPROC (1 << 14) /*
> Timer Restart */
> > #define AT91_WDT_WDDIS (1 << 15) /*
> Watchdog Disable */
> > #define AT91_WDT_WDD (0xfff << 16) /*
> Delta Value */
> > +#define AT91_WDT_SET_WDD(x) (((x) << 16) &
> AT91_WDT_WDD)
> > #define AT91_WDT_WDDBGHLT (1 << 28) /*
> Debug Halt */
> > #define AT91_WDT_WDIDLEHLT (1 << 29) /*
> Idle Halt */
> >
> >
Best Regards,
Wenyou Yang