linux-kernel - Re: [PATCH v2 1/6] rtc: omap: kicker mechanism support

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Message-ID: <500FD551.9070002@mvista.com>
Date:	Wed, 25 Jul 2012 15:15:29 +0400
From:	Sergei Shtylyov <sshtylyov@...sta.com>
To:	Afzal Mohammed <afzal@...com>
CC:	grant.likely@...retlab.ca, rob.herring@...xeda.com,
	rob@...dley.net, linux@....linux.org.uk, nsekhar@...com,
	khilman@...com, a.zummo@...ertech.it, tony@...mide.com,
	devicetree-discuss@...ts.ozlabs.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	davinci-linux-open-source@...ux.davincidsp.com,
	rtc-linux@...glegroups.com
Subject: Re: [PATCH v2 1/6] rtc: omap: kicker mechanism support

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@...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

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