Re: [PATCH 1/2] mn10300: use RTC_DRV_CMOS instead of CONFIG_RTC

[Alexandre Belloni]

On 01/06/2016 at 16:46:22 +0200, Arnd Bergmann wrote :
> nn10300 has a dependency on mc146818_get_time/mc146818_set_time,
> which we want to move from the mc146818rtc.h header into the
> rtc subsystem, which in turn is not usable on mn10300.
> 
> This changes mn10300 to use the modern rtc-cmos driver instead
> of the old RTC driver, and that in turn lets us completely
> remove the read_persistent_clock/update_persistent_clock callbacks.
> 
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
> ---
> We should probably get both these patches through the rtc tree, but
> it would be nice to have some confirmation from the mn10300 maintainer
> that this is a reasonable patch.
> 

Well without any comment, I'm taking both patches now.

>  arch/mn10300/Kconfig                    |   4 +-
>  arch/mn10300/include/asm/rtc-regs.h     |   4 +-
>  arch/mn10300/kernel/rtc.c               | 104 +++-----------------------------
>  arch/mn10300/proc-mn103e010/proc-init.c |   1 +
>  drivers/char/Kconfig                    |   2 +-
>  drivers/rtc/Kconfig                     |   2 +-
>  drivers/rtc/rtc-cmos.c                  |   2 +-
>  7 files changed, 18 insertions(+), 101 deletions(-)
> 
> diff --git a/arch/mn10300/Kconfig b/arch/mn10300/Kconfig
> index 9627e81a6cbb..38e3494bfb63 100644
> --- a/arch/mn10300/Kconfig
> +++ b/arch/mn10300/Kconfig
> @@ -236,7 +236,9 @@ source "kernel/Kconfig.hz"
>  config MN10300_RTC
>  	bool "Using MN10300 RTC"
>  	depends on MN10300_PROC_MN103E010 || MN10300_PROC_MN2WS0050
> -	select GENERIC_CMOS_UPDATE
> +	select RTC_CLASS
> +	select RTC_DRV_CMOS
> +	select RTC_SYSTOHC
>  	default n
>  	help
>  	  This option enables support for the RTC, thus enabling time to be
> diff --git a/arch/mn10300/include/asm/rtc-regs.h b/arch/mn10300/include/asm/rtc-regs.h
> index c42deefaec11..c81cacecb6e3 100644
> --- a/arch/mn10300/include/asm/rtc-regs.h
> +++ b/arch/mn10300/include/asm/rtc-regs.h
> @@ -75,9 +75,9 @@
>  #define RTC_PORT(x)		0xd8600000
>  #define RTC_ALWAYS_BCD		1	/* RTC operates in binary mode */
>  
> -#define CMOS_READ(addr)		__SYSREG(0xd8600000 + (addr), u8)
> +#define CMOS_READ(addr)		__SYSREG(0xd8600000 + (u32)(addr), u8)
>  #define CMOS_WRITE(val, addr)	\
> -	do { __SYSREG(0xd8600000 + (addr), u8) = val; } while (0)
> +	do { __SYSREG(0xd8600000 + (u32)(addr), u8) = val; } while (0)
>  
>  #define RTC_IRQ			RTIRQ
>  
> diff --git a/arch/mn10300/kernel/rtc.c b/arch/mn10300/kernel/rtc.c
> index 77e0be4d92ea..f81f37025072 100644
> --- a/arch/mn10300/kernel/rtc.c
> +++ b/arch/mn10300/kernel/rtc.c
> @@ -12,107 +12,19 @@
>  #include <linux/module.h>
>  #include <linux/init.h>
>  #include <linux/mc146818rtc.h>
> -#include <linux/bcd.h>
> -#include <linux/timex.h>
> +#include <linux/ioport.h>
> +#include <linux/platform_device.h>
> +
>  #include <asm/rtc-regs.h>
>  #include <asm/rtc.h>
>  
>  DEFINE_SPINLOCK(rtc_lock);
>  EXPORT_SYMBOL(rtc_lock);
>  
> -/*
> - * Read the current RTC time
> - */
> -void read_persistent_clock(struct timespec *ts)
> -{
> -	struct rtc_time tm;
> -
> -	mc146818_set_time(&tm);
> -
> -	ts->tv_nsec = 0;
> -	ts->tv_sec = mktime(tm.tm_year, tm.tm_mon, tm.tm_mday,
> -			    tm.tm_hour, tm.tm_min, tm.tm_sec);
> -
> -	/* if rtc is way off in the past, set something reasonable */
> -	if (ts->tv_sec < 0)
> -		ts->tv_sec = mktime(2009, 1, 1, 12, 0, 0);
> -}
> -
> -/*
> - * In order to set the CMOS clock precisely, set_rtc_mmss has to be called 500
> - * ms after the second nowtime has started, because when nowtime is written
> - * into the registers of the CMOS clock, it will jump to the next second
> - * precisely 500 ms later.  Check the Motorola MC146818A or Dallas DS12887 data
> - * sheet for details.
> - *
> - * BUG: This routine does not handle hour overflow properly; it just
> - *      sets the minutes. Usually you'll only notice that after reboot!
> - */
> -static int set_rtc_mmss(unsigned long nowtime)
> -{
> -	unsigned char save_control, save_freq_select;
> -	int retval = 0;
> -	int real_seconds, real_minutes, cmos_minutes;
> -
> -	/* gets recalled with irq locally disabled */
> -	spin_lock(&rtc_lock);
> -	save_control = CMOS_READ(RTC_CONTROL); /* tell the clock it's being
> -						* set */
> -	CMOS_WRITE(save_control | RTC_SET, RTC_CONTROL);
> -
> -	save_freq_select = CMOS_READ(RTC_FREQ_SELECT); /* stop and reset
> -							* prescaler */
> -	CMOS_WRITE(save_freq_select | RTC_DIV_RESET2, RTC_FREQ_SELECT);
> -
> -	cmos_minutes = CMOS_READ(RTC_MINUTES);
> -	if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD)
> -		cmos_minutes = bcd2bin(cmos_minutes);
> -
> -	/*
> -	 * since we're only adjusting minutes and seconds,
> -	 * don't interfere with hour overflow. This avoids
> -	 * messing with unknown time zones but requires your
> -	 * RTC not to be off by more than 15 minutes
> -	 */
> -	real_seconds = nowtime % 60;
> -	real_minutes = nowtime / 60;
> -	if (((abs(real_minutes - cmos_minutes) + 15) / 30) & 1)
> -		/* correct for half hour time zone */
> -		real_minutes += 30;
> -	real_minutes %= 60;
> -
> -	if (abs(real_minutes - cmos_minutes) < 30) {
> -		if (!(save_control & RTC_DM_BINARY) || RTC_ALWAYS_BCD) {
> -			real_seconds = bin2bcd(real_seconds);
> -			real_minutes = bin2bcd(real_minutes);
> -		}
> -		CMOS_WRITE(real_seconds, RTC_SECONDS);
> -		CMOS_WRITE(real_minutes, RTC_MINUTES);
> -	} else {
> -		printk_once(KERN_NOTICE
> -		       "set_rtc_mmss: can't update from %d to %d\n",
> -		       cmos_minutes, real_minutes);
> -		retval = -1;
> -	}
> -
> -	/* The following flags have to be released exactly in this order,
> -	 * otherwise the DS12887 (popular MC146818A clone with integrated
> -	 * battery and quartz) will not reset the oscillator and will not
> -	 * update precisely 500 ms later. You won't find this mentioned in
> -	 * the Dallas Semiconductor data sheets, but who believes data
> -	 * sheets anyway ...                           -- Markus Kuhn
> -	 */
> -	CMOS_WRITE(save_control, RTC_CONTROL);
> -	CMOS_WRITE(save_freq_select, RTC_FREQ_SELECT);
> -	spin_unlock(&rtc_lock);
> -
> -	return retval;
> -}
> -
> -int update_persistent_clock(struct timespec now)
> -{
> -	return set_rtc_mmss(now.tv_sec);
> -}
> +static const __initdata struct resource res[] = {
> +	DEFINE_RES_IO(RTC_PORT(0), RTC_IO_EXTENT),
> +	DEFINE_RES_IRQ(RTC_IRQ),
> +};
>  
>  /*
>   * calibrate the TSC clock against the RTC
> @@ -129,4 +41,6 @@ void __init calibrate_clock(void)
>  	RTCRA |= RTCRA_DVR;
>  	RTCRA &= ~RTCRA_DVR;
>  	RTCRB &= ~RTCRB_SET;
> +
> +	platform_device_register_simple("rtc_cmos", -1, res, ARRAY_SIZE(res));
>  }
> diff --git a/arch/mn10300/proc-mn103e010/proc-init.c b/arch/mn10300/proc-mn103e010/proc-init.c
> index d4dcb0c56b35..f4990dffff94 100644
> --- a/arch/mn10300/proc-mn103e010/proc-init.c
> +++ b/arch/mn10300/proc-mn103e010/proc-init.c
> @@ -9,6 +9,7 @@
>   * 2 of the Licence, or (at your option) any later version.
>   */
>  #include <linux/kernel.h>
> +#include <linux/irq.h>
>  #include <asm/cacheflush.h>
>  #include <asm/fpu.h>
>  #include <asm/rtc.h>
> diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
> index 0ec91cc6c2fb..273b5492fbcf 100644
> --- a/drivers/char/Kconfig
> +++ b/drivers/char/Kconfig
> @@ -279,7 +279,7 @@ if RTC_LIB=n
>  
>  config RTC
>  	tristate "Enhanced Real Time Clock Support (legacy PC RTC driver)"
> -	depends on ALPHA || (MIPS && MACH_LOONGSON64) || MN10300
> +	depends on ALPHA || (MIPS && MACH_LOONGSON64)
>  	---help---
>  	  If you say Y here and create a character special file /dev/rtc with
>  	  major number 10 and minor number 135 using mknod ("man mknod"), you
> diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig
> index 18639e0cb6e2..e8ef709f3945 100644
> --- a/drivers/rtc/Kconfig
> +++ b/drivers/rtc/Kconfig
> @@ -795,7 +795,7 @@ comment "Platform RTC drivers"
>  
>  config RTC_DRV_CMOS
>  	tristate "PC-style 'CMOS'"
> -	depends on X86 || ARM || M32R || PPC || MIPS || SPARC64
> +	depends on X86 || ARM || M32R || PPC || MIPS || SPARC64 || MN10300
>  	default y if X86
>  	help
>  	  Say "yes" here to get direct support for the real time clock
> diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c
> index cf8eb98382ce..f9fdb6fc641c 100644
> --- a/drivers/rtc/rtc-cmos.c
> +++ b/drivers/rtc/rtc-cmos.c
> @@ -630,7 +630,7 @@ cmos_do_probe(struct device *dev, struct resource *ports, int rtc_irq)
>  	address_space = 64;
>  #elif defined(__i386__) || defined(__x86_64__) || defined(__arm__) \
>  			|| defined(__sparc__) || defined(__mips__) \
> -			|| defined(__powerpc__)
> +			|| defined(__powerpc__) || defined(CONFIG_MN10300)
>  	address_space = 128;
>  #else
>  #warning Assuming 128 bytes of RTC+NVRAM address space, not 64 bytes.
> -- 
> 2.7.0
> 

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com