Patchwork [v2,1/6] rtc: omap: kicker mechanism support

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Submitter Mohammed Afzal
Date July 25, 2012, 6:12 a.m.
Message ID <ecf6520fc9d5da53b670675a71ebece3d006cbb8.1343191280.git.afzal@ti.com>
Download mbox | patch
Permalink /patch/173110/
State New
Headers show

Comments

Mohammed Afzal - July 25, 2012, 6:12 a.m.
OMAP RTC IP can have kicker feature. This prevents spurious
writes to register. To write to registers kicker lock has to
be released. Procedure to do it as follows,

1. write to kick0 register, 0x83e70b13
2. write to kick1 register, 0x95a4f1e0

Writing value other than 0x83e70b13 to kick0 enables write
locking, more details about kicker mechanism can be found in
section 20.3.3.5.3 of AM335X TRM @www.ti.com/am335x

Here id table information is added and is used to distinguish
those that require kicker handling and the ones that doesn't
need it. There are more features in the newer IP's compared
to legacy ones other than kicker, which driver currently
doesn't handle, supporting additional features would be
easier with the addition of id table.

Older IP (of OMAP1) doesn't have revision register as per
TRM, so revision register can't be relied always to find
features, hence id table is being used.

Signed-off-by: Afzal Mohammed <afzal@ti.com>
---

v2:
 Use device name da830-rtc instead of am1808-rtc
 Newly added register name made similar to that existing in the driver
 Better commit message description

 drivers/rtc/rtc-omap.c |   39 ++++++++++++++++++++++++++++++++++++++-
 1 files changed, 38 insertions(+), 1 deletions(-)
Sergei Shtylyov - July 25, 2012, 11:15 a.m.
Hello.

On 25-07-2012 10:12, Afzal Mohammed wrote:

> OMAP RTC IP can have kicker feature. This prevents spurious
> writes to register. To write to registers kicker lock has to
> be released. Procedure to do it as follows,

> 1. write to kick0 register, 0x83e70b13
> 2. write to kick1 register, 0x95a4f1e0

> Writing value other than 0x83e70b13 to kick0 enables write
> locking, more details about kicker mechanism can be found in
> section 20.3.3.5.3 of AM335X TRM @www.ti.com/am335x

> Here id table information is added and is used to distinguish
> those that require kicker handling and the ones that doesn't
> need it. There are more features in the newer IP's compared
> to legacy ones other than kicker, which driver currently
> doesn't handle, supporting additional features would be
> easier with the addition of id table.

> Older IP (of OMAP1) doesn't have revision register as per
> TRM, so revision register can't be relied always to find
> features, hence id table is being used.

> Signed-off-by: Afzal Mohammed <afzal@ti.com>
> ---

> v2:
>   Use device name da830-rtc instead of am1808-rtc
>   Newly added register name made similar to that existing in the driver
>   Better commit message description

>   drivers/rtc/rtc-omap.c |   39 ++++++++++++++++++++++++++++++++++++++-
>   1 files changed, 38 insertions(+), 1 deletions(-)

> diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
> index 0b614e3..8afbc2e 100644
> --- a/drivers/rtc/rtc-omap.c
> +++ b/drivers/rtc/rtc-omap.c
> @@ -38,6 +38,8 @@
>    * the SoC). See the BOARD-SPECIFIC CUSTOMIZATION comment.
>    */
>
> +#define	DRIVER_NAME			"omap_rtc"
> +
>   #define OMAP_RTC_BASE			0xfffb4800
>
>   /* RTC registers */
> @@ -64,6 +66,9 @@
>   #define OMAP_RTC_COMP_MSB_REG		0x50
>   #define OMAP_RTC_OSC_REG		0x54
>
> +#define OMAP_RTC_KICK0_REG		0x6c
> +#define OMAP_RTC_KICK1_REG		0x70
> +
>   /* OMAP_RTC_CTRL_REG bit fields: */
>   #define OMAP_RTC_CTRL_SPLIT		(1<<7)
>   #define OMAP_RTC_CTRL_DISABLE		(1<<6)
> @@ -88,11 +93,19 @@
>   #define OMAP_RTC_INTERRUPTS_IT_ALARM    (1<<3)
>   #define OMAP_RTC_INTERRUPTS_IT_TIMER    (1<<2)
>
> +/* OMAP_RTC_KICKER values */
> +#define	KICK0_VALUE			(0x83e70b13)
> +#define	KICK1_VALUE			(0x95a4f1e0)

    Parens not needed around simple literals.

>   static void __iomem	*rtc_base;
>
>   #define rtc_read(addr)		__raw_readb(rtc_base + (addr))
>   #define rtc_write(val, addr)	__raw_writeb(val, rtc_base + (addr))
>
> +#define rtc_writel(val, addr)	writel(val, rtc_base + (addr))
> +

    Why not __raw_writel() like the above functions?

WBR, Sergei
Mohammed Afzal - July 25, 2012, 2:01 p.m.
Hi Sergei,

On Wed, Jul 25, 2012 at 16:45:29, Sergei Shtylyov wrote:

> > +/* OMAP_RTC_KICKER values */
> > +#define	KICK0_VALUE			(0x83e70b13)
> > +#define	KICK1_VALUE			(0x95a4f1e0)
> 
>     Parens not needed around simple literals.

Thanks for catching it

> 
> >   static void __iomem	*rtc_base;
> >
> >   #define rtc_read(addr)		__raw_readb(rtc_base + (addr))
> >   #define rtc_write(val, addr)	__raw_writeb(val, rtc_base + (addr))
> >
> > +#define rtc_writel(val, addr)	writel(val, rtc_base + (addr))
> > +
> 
>     Why not __raw_writel() like the above functions?

This driver would be used in AM335X, it being ARMv7, writel would be
safe (existing __raw_readb/__raw_writeb too needs to be replaced)

Regards
Afzal

Patch

diff --git a/drivers/rtc/rtc-omap.c b/drivers/rtc/rtc-omap.c
index 0b614e3..8afbc2e 100644
--- a/drivers/rtc/rtc-omap.c
+++ b/drivers/rtc/rtc-omap.c
@@ -38,6 +38,8 @@ 
  * the SoC). See the BOARD-SPECIFIC CUSTOMIZATION comment.
  */
 
+#define	DRIVER_NAME			"omap_rtc"
+
 #define OMAP_RTC_BASE			0xfffb4800
 
 /* RTC registers */
@@ -64,6 +66,9 @@ 
 #define OMAP_RTC_COMP_MSB_REG		0x50
 #define OMAP_RTC_OSC_REG		0x54
 
+#define OMAP_RTC_KICK0_REG		0x6c
+#define OMAP_RTC_KICK1_REG		0x70
+
 /* OMAP_RTC_CTRL_REG bit fields: */
 #define OMAP_RTC_CTRL_SPLIT		(1<<7)
 #define OMAP_RTC_CTRL_DISABLE		(1<<6)
@@ -88,11 +93,19 @@ 
 #define OMAP_RTC_INTERRUPTS_IT_ALARM    (1<<3)
 #define OMAP_RTC_INTERRUPTS_IT_TIMER    (1<<2)
 
+/* OMAP_RTC_KICKER values */
+#define	KICK0_VALUE			(0x83e70b13)
+#define	KICK1_VALUE			(0x95a4f1e0)
+
+#define	OMAP_RTC_HAS_KICKER		0x1
+
 static void __iomem	*rtc_base;
 
 #define rtc_read(addr)		__raw_readb(rtc_base + (addr))
 #define rtc_write(val, addr)	__raw_writeb(val, rtc_base + (addr))
 
+#define rtc_writel(val, addr)	writel(val, rtc_base + (addr))
+
 
 /* we rely on the rtc framework to handle locking (rtc->ops_lock),
  * so the only other requirement is that register accesses which
@@ -285,11 +298,22 @@  static struct rtc_class_ops omap_rtc_ops = {
 static int omap_rtc_alarm;
 static int omap_rtc_timer;
 
+static struct platform_device_id omap_rtc_devtype[] = {
+	{
+		.name	= DRIVER_NAME,
+	}, {
+		.name	= "da830-rtc",
+		.driver_data = OMAP_RTC_HAS_KICKER,
+	}
+};
+MODULE_DEVICE_TABLE(platform, omap_rtc_devtype);
+
 static int __init omap_rtc_probe(struct platform_device *pdev)
 {
 	struct resource		*res, *mem;
 	struct rtc_device	*rtc;
 	u8			reg, new_ctrl;
+	const struct platform_device_id *id_entry;
 
 	omap_rtc_timer = platform_get_irq(pdev, 0);
 	if (omap_rtc_timer <= 0) {
@@ -322,6 +346,12 @@  static int __init omap_rtc_probe(struct platform_device *pdev)
 		goto fail;
 	}
 
+	id_entry = platform_get_device_id(pdev);
+	if (id_entry && (id_entry->driver_data & OMAP_RTC_HAS_KICKER)) {
+		rtc_writel(KICK0_VALUE, OMAP_RTC_KICK0_REG);
+		rtc_writel(KICK1_VALUE, OMAP_RTC_KICK1_REG);
+	}
+
 	rtc = rtc_device_register(pdev->name, &pdev->dev,
 			&omap_rtc_ops, THIS_MODULE);
 	if (IS_ERR(rtc)) {
@@ -398,6 +428,8 @@  fail2:
 fail1:
 	rtc_device_unregister(rtc);
 fail0:
+	if (id_entry && (id_entry->driver_data & OMAP_RTC_HAS_KICKER))
+		rtc_writel(0, OMAP_RTC_KICK0_REG);
 	iounmap(rtc_base);
 fail:
 	release_mem_region(mem->start, resource_size(mem));
@@ -408,6 +440,8 @@  static int __exit omap_rtc_remove(struct platform_device *pdev)
 {
 	struct rtc_device	*rtc = platform_get_drvdata(pdev);
 	struct resource		*mem = dev_get_drvdata(&rtc->dev);
+	const struct platform_device_id *id_entry =
+				platform_get_device_id(pdev);
 
 	device_init_wakeup(&pdev->dev, 0);
 
@@ -420,6 +454,8 @@  static int __exit omap_rtc_remove(struct platform_device *pdev)
 		free_irq(omap_rtc_alarm, rtc);
 
 	rtc_device_unregister(rtc);
+	if (id_entry && (id_entry->driver_data & OMAP_RTC_HAS_KICKER))
+		rtc_writel(0, OMAP_RTC_KICK0_REG);
 	iounmap(rtc_base);
 	release_mem_region(mem->start, resource_size(mem));
 	return 0;
@@ -471,9 +507,10 @@  static struct platform_driver omap_rtc_driver = {
 	.resume		= omap_rtc_resume,
 	.shutdown	= omap_rtc_shutdown,
 	.driver		= {
-		.name	= "omap_rtc",
+		.name	= DRIVER_NAME,
 		.owner	= THIS_MODULE,
 	},
+	.id_table	= omap_rtc_devtype,
 };
 
 static int __init rtc_init(void)