[PATCH 1/2] Watchdog: omap_wdt: Retrieve bootstatus via syscon

[PATCH 1/2] Watchdog: omap_wdt: Retrieve bootstatus via syscon

[Cor Peters]

The current way to retrieve the bootstatus does not work with
device-tree based systems. This patch uses syscon to retrieve the
watchdog boot status from the PRM_DEV registers.

Signed-off-by: Cor Peters <cpeters-JQzsJ8WnmGqc6Wr4J9gsBQC/G2K4zDHf@public.gmane.org>
---
 drivers/watchdog/omap_wdt.c | 16 ++++++++++++++--
 1 file changed, 14 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/omap_wdt.c b/drivers/watchdog/omap_wdt.c
index 1b02bfa..fed3f9c 100644
--- a/drivers/watchdog/omap_wdt.c
+++ b/drivers/watchdog/omap_wdt.c
@@ -41,6 +41,8 @@
 #include <linux/slab.h>
 #include <linux/pm_runtime.h>
 #include <linux/platform_data/omap-wd-timer.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
 
 #include "omap_wdt.h"
 
@@ -230,9 +232,11 @@ static unsigned int omap_wdt_get_timeleft(struct watchdog_device *wdog)
 static int omap_wdt_probe(struct platform_device *pdev)
 {
        struct omap_wd_timer_platform_data *pdata = dev_get_platdata(&pdev->dev);
+       struct regmap *rm = syscon_regmap_lookup_by_compatible("ti,omap3-prcm-dev");
        struct resource *res;
        struct omap_wdt_dev *wdev;
        int ret;
+       u32 rs = 0;
 
        wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
        if (!wdev)
@@ -267,9 +271,17 @@ static int omap_wdt_probe(struct platform_device *pdev)
 
        if (pdata && pdata->read_reset_sources) {
                u32 rs = pdata->read_reset_sources();
-               if (rs & (1 << OMAP_MPU_WD_RST_SRC_ID_SHIFT))
-                       wdev->wdog.bootstatus = WDIOF_CARDRESET;
        }
+       else if (!IS_ERR(rm)) {
+               if (regmap_read(rm, 2 * sizeof(u32), &rs) >= 0) {
+                       /* reset register */
+                       regmap_write(rm, 2 * sizeof(u32),
+                               (1 << OMAP_MPU_WD_RST_SRC_ID_SHIFT) );
+               }
+       }
+
+       if (rs & (1 << OMAP_MPU_WD_RST_SRC_ID_SHIFT))
+               wdev->wdog.bootstatus = WDIOF_CARDRESET;
 
        if (!early_enable)
                omap_wdt_disable(wdev);
-- 
1.9.1

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Re: [PATCH 1/2] Watchdog: omap_wdt: Retrieve bootstatus via syscon

[Guenter Roeck]

On 11/15/2016 12:44 AM, Cor Peters wrote:
> The current way to retrieve the bootstatus does not work with
> device-tree based systems. This patch uses syscon to retrieve the
> watchdog boot status from the PRM_DEV registers.
>
> Signed-off-by: Cor Peters <cpeters-JQzsJ8WnmGqc6Wr4J9gsBQC/G2K4zDHf@public.gmane.org>

For the subject: Patch 2/2 seems to be missing (or I wasn't copied).

> ---
>  drivers/watchdog/omap_wdt.c | 16 ++++++++++++++--
>  1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/watchdog/omap_wdt.c b/drivers/watchdog/omap_wdt.c
> index 1b02bfa..fed3f9c 100644
> --- a/drivers/watchdog/omap_wdt.c
> +++ b/drivers/watchdog/omap_wdt.c
> @@ -41,6 +41,8 @@
>  #include <linux/slab.h>
>  #include <linux/pm_runtime.h>
>  #include <linux/platform_data/omap-wd-timer.h>
> +#include <linux/regmap.h>
> +#include <linux/mfd/syscon.h>
>
>  #include "omap_wdt.h"
>
> @@ -230,9 +232,11 @@ static unsigned int omap_wdt_get_timeleft(struct watchdog_device *wdog)
>  static int omap_wdt_probe(struct platform_device *pdev)
>  {
>         struct omap_wd_timer_platform_data *pdata = dev_get_platdata(&pdev->dev);
> +       struct regmap *rm = syscon_regmap_lookup_by_compatible("ti,omap3-prcm-dev");
>         struct resource *res;
>         struct omap_wdt_dev *wdev;
>         int ret;
> +       u32 rs = 0;
>
>         wdev = devm_kzalloc(&pdev->dev, sizeof(*wdev), GFP_KERNEL);
>         if (!wdev)
> @@ -267,9 +271,17 @@ static int omap_wdt_probe(struct platform_device *pdev)
>
>         if (pdata && pdata->read_reset_sources) {
>                 u32 rs = pdata->read_reset_sources();

You are still declaring rs here, meaning the new instance of rs is hidden.

> -               if (rs & (1 << OMAP_MPU_WD_RST_SRC_ID_SHIFT))
> -                       wdev->wdog.bootstatus = WDIOF_CARDRESET;
>         }
> +       else if (!IS_ERR(rm)) {
> +               if (regmap_read(rm, 2 * sizeof(u32), &rs) >= 0) {

Can you use a define instead of "2 * sizeof(u32)" here ? If the register is 0x0008
it should be defined as 0x0008; the register address does not depend on the size
of an u32.

> +                       /* reset register */
> +                       regmap_write(rm, 2 * sizeof(u32),
> +                               (1 << OMAP_MPU_WD_RST_SRC_ID_SHIFT) );

extra space between '')'.

Why reset this register ? That isn't done for the non-DT case.

Also, unless I misunderstand the code, OMAP_MPU_WD_RST_SRC_ID_SHIFT is a
standardized "soft" value and does not reflect the physical reset bit in
the SoC. I don't think you can just use that value and assume that it
is the correct register bit to use.

Guenter

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