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Message-ID: <533234DB.1030705@roeck-us.net>
Date: Tue, 25 Mar 2014 19:00:59 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Xiubo Li <Li.Xiubo@...escale.com>, wim@...ana.be,
w.sang@...gutronix.de, linux-watchdog@...r.kernel.org
CC: linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] watchdog: imx2_wdt: Add big-endian support
On 03/25/2014 02:35 AM, Xiubo Li wrote:
> Signed-off-by: Xiubo Li <Li.Xiubo@...escale.com>
> ---
There is no explanation for this patch in the headline.
Ultimately there are four cases
CPU HW
little little
little big
big little
big big
Current code handles big/big as well as little/little, and you are adding
little/big to the list of supported combinations. Questions are
1) which combinations are possible ?
2) is big/little a combination which needs to be handled as well ?
The "big-endians" property is new and will have to be approved by the
DT maintainers. If in fact needed, I would suggest to use "big-endian"
as this seems to be more common.
Guenter
> drivers/watchdog/imx2_wdt.c | 40 +++++++++++++++++++++++++++++++---------
> 1 file changed, 31 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
> index 1795922..c410981 100644
> --- a/drivers/watchdog/imx2_wdt.c
> +++ b/drivers/watchdog/imx2_wdt.c
> @@ -30,6 +30,7 @@
> #include <linux/miscdevice.h>
> #include <linux/module.h>
> #include <linux/moduleparam.h>
> +#include <linux/of.h>
> #include <linux/platform_device.h>
> #include <linux/timer.h>
> #include <linux/uaccess.h>
> @@ -64,9 +65,26 @@ static struct {
> void __iomem *base;
> unsigned timeout;
> unsigned long status;
> + bool big_endian;
> struct timer_list timer; /* Pings the watchdog when closed */
> } imx2_wdt;
>
> +static inline u16 imx2_wdt_readw(void __iomem *addr)
> +{
> + if (imx2_wdt.big_endian)
> + return ioread16be(addr);
> + else
> + return ioread16(addr);
> +}
> +
> +static inline void imx2_wdt_writew(u16 val, void __iomem *addr)
> +{
> + if (imx2_wdt.big_endian)
> + iowrite16be(val, addr);
> + else
> + iowrite16(val, addr);
> +}
> +
> static struct miscdevice imx2_wdt_miscdev;
>
> static bool nowayout = WATCHDOG_NOWAYOUT;
> @@ -87,7 +105,7 @@ static const struct watchdog_info imx2_wdt_info = {
>
> static inline void imx2_wdt_setup(void)
> {
> - u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
> + u16 val = imx2_wdt_readw(imx2_wdt.base + IMX2_WDT_WCR);
>
> /* Suspend timer in low power mode, write once-only */
> val |= IMX2_WDT_WCR_WDZST;
> @@ -100,17 +118,17 @@ static inline void imx2_wdt_setup(void)
> /* Set the watchdog's Time-Out value */
> val |= WDOG_SEC_TO_COUNT(imx2_wdt.timeout);
>
> - __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
> + imx2_wdt_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
>
> /* enable the watchdog */
> val |= IMX2_WDT_WCR_WDE;
> - __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
> + imx2_wdt_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
> }
>
> static inline void imx2_wdt_ping(void)
> {
> - __raw_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
> - __raw_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
> + imx2_wdt_writew(IMX2_WDT_SEQ1, imx2_wdt.base + IMX2_WDT_WSR);
> + imx2_wdt_writew(IMX2_WDT_SEQ2, imx2_wdt.base + IMX2_WDT_WSR);
> }
>
> static void imx2_wdt_timer_ping(unsigned long arg)
> @@ -143,12 +161,12 @@ static void imx2_wdt_stop(void)
>
> static void imx2_wdt_set_timeout(int new_timeout)
> {
> - u16 val = __raw_readw(imx2_wdt.base + IMX2_WDT_WCR);
> + u16 val = imx2_wdt_readw(imx2_wdt.base + IMX2_WDT_WCR);
>
> /* set the new timeout value in the WSR */
> val &= ~IMX2_WDT_WCR_WT;
> val |= WDOG_SEC_TO_COUNT(new_timeout);
> - __raw_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
> + imx2_wdt_writew(val, imx2_wdt.base + IMX2_WDT_WCR);
> }
>
> static int imx2_wdt_open(struct inode *inode, struct file *file)
> @@ -192,7 +210,7 @@ static long imx2_wdt_ioctl(struct file *file, unsigned int cmd,
> return put_user(0, p);
>
> case WDIOC_GETBOOTSTATUS:
> - val = __raw_readw(imx2_wdt.base + IMX2_WDT_WRSR);
> + val = imx2_wdt_readw(imx2_wdt.base + IMX2_WDT_WRSR);
> new_value = val & IMX2_WDT_WRSR_TOUT ? WDIOF_CARDRESET : 0;
> return put_user(new_value, p);
>
> @@ -257,8 +275,12 @@ static struct miscdevice imx2_wdt_miscdev = {
>
> static int __init imx2_wdt_probe(struct platform_device *pdev)
> {
> - int ret;
> + struct device_node *np = pdev->dev.of_node;
> struct resource *res;
> + int ret;
> +
> + if (np)
> + imx2_wdt.big_endian = of_property_read_bool(np, "big-endians");
>
> res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> imx2_wdt.base = devm_ioremap_resource(&pdev->dev, res);
>
--
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