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SubjectRe: [PATCH] rtc: rs5c372: r2221: fix to use the correct XSTP bit
Hello,

On 09/01/2019 10:59:40+0000, Oliver.Rohe@wago.com wrote:
> The Ricoh chips have slightly different register layouts
> and the r2221 chip uses bit 5 as the oscillator halt sensor bit.
>
> Signed-off-by: Olive Rohe <oliver.rohe@wago.com>
> ---
> drivers/rtc/rtc-rs5c372.c | 32 +++++++++++++++++++++-----------
> 1 file changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/rtc/rtc-rs5c372.c b/drivers/rtc/rtc-rs5c372.c
> index c503832..ff35dce 100644
> --- a/drivers/rtc/rtc-rs5c372.c
> +++ b/drivers/rtc/rtc-rs5c372.c
> @@ -52,8 +52,8 @@
> # define RS5C_CTRL1_CT4 (4 << 0) /* 1 Hz level irq */
> #define RS5C_REG_CTRL2 15
> # define RS5C372_CTRL2_24 (1 << 5)
> -# define R2025_CTRL2_XST (1 << 5)
> -# define RS5C_CTRL2_XSTP (1 << 4) /* only if !R2025S/D */
> +# define R2x2x_CTRL2_XSTP (1 << 5) /* only if R2x2x */

I wouldn't rename that define as later on, it may be used for RTCs that
doesn't match R2x2x (as is the case for RV5C387_CTRL1_24 for example).
the bit doesn't even have the same meaning on R2025 and R2221.

> +# define RS5C_CTRL2_XSTP (1 << 4) /* only if !R2x2x */
> # define RS5C_CTRL2_CTFG (1 << 2)
> # define RS5C_CTRL2_AAFG (1 << 1) /* or WAFG */
> # define RS5C_CTRL2_BAFG (1 << 0) /* or DAFG */
> @@ -519,20 +519,30 @@ static int rs5c_oscillator_setup(struct rs5c372 *rs5c372)
> unsigned char buf[2];
> int addr, i, ret = 0;
>
> - if (rs5c372->type == rtc_r2025sd) {
> - if (rs5c372->regs[RS5C_REG_CTRL2] & R2025_CTRL2_XST)
> + addr = RS5C_ADDR(RS5C_REG_CTRL1);
> + buf[0] = rs5c372->regs[RS5C_REG_CTRL1];
> + buf[1] = rs5c372->regs[RS5C_REG_CTRL2];
> +
> + /* handle xstp bit */
> + switch (rs5c372->type) {
> + case rtc_r2025sd:
> + if (buf[1] & R2x2x_CTRL2_XSTP)
> return ret;
> - rs5c372->regs[RS5C_REG_CTRL2] |= R2025_CTRL2_XST;
> - } else {
> - if (!(rs5c372->regs[RS5C_REG_CTRL2] & RS5C_CTRL2_XSTP))
> + rs5c372->regs[RS5C_REG_CTRL2] |= R2x2x_CTRL2_XSTP;
> + break;
> + case rtc_r2221tl:
> + if (!(buf[1] & R2x2x_CTRL2_XSTP))
> + return ret;
> + rs5c372->regs[RS5C_REG_CTRL2] &= ~R2x2x_CTRL2_XSTP;
> + break;
> +
> + default:
> + if (!(buf[1] & RS5C_CTRL2_XSTP))
> return ret;
> rs5c372->regs[RS5C_REG_CTRL2] &= ~RS5C_CTRL2_XSTP;
> + break;
> }
>

Note that this is actually quite bad to restart the oscillator on probe.
The best would be to do that only in rs5c372_rtc_set_time once you know
the set time is good. then you can return -EINVAL from
rs5c372_rtc_read_time when you know the oscillator is stopped so
userspace know the RTC time is bad. This could be done as a follw up
patch.

There is also more work needed to clean up that driver if you have time
and are willing to.

--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

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