From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Perches Subject: Re: [PATCH v2] clk: si570: Add a driver for SI570 oscillators Date: Wed, 18 Sep 2013 16:18:56 -0700 Message-ID: <1379546336.1787.95.camel@joe-AO722> References: <1379544219-23579-1-git-send-email-soren.brinkmann@xilinx.com> <1379545361.1787.87.camel@joe-AO722> <0da25c5c-660c-4836-8179-6e7c51fd0d9f@CO9EHSMHS005.ehs.local> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <0da25c5c-660c-4836-8179-6e7c51fd0d9f-QhSrsHip19tEus+KprP3J7jjLBE8jN/0@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: =?ISO-8859-1?Q?S=F6ren?= Brinkmann Cc: Rob Herring , Pawel Moll , Mark Rutland , Stephen Warren , Ian Campbell , Rob Landley , Mike Turquette , Grant Likely , Guenter Roeck , Sebastian Hesselbarth , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-doc-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Hyun Kwon List-Id: devicetree@vger.kernel.org On Wed, 2013-09-18 at 16:09 -0700, S=F6ren Brinkmann wrote: > On Wed, Sep 18, 2013 at 04:02:41PM -0700, Joe Perches wrote: > > On Wed, 2013-09-18 at 15:43 -0700, Soren Brinkmann wrote: > > > Add a driver for SILabs 570, 571, 598, 599 programmable oscillato= rs. > > > The devices generate low-jitter clock signals and are reprogramma= ble via > > > an I2C interface. > > [] > > > v2: > > [] > > > - use 10000 as MIN and MAX value in usleep_range > > [] > > > diff --git a/drivers/clk/clk-si570.c b/drivers/clk/clk-si570.c > > [] > > > +static int si570_set_frequency(struct clk_si570 *data, unsigned = long frequency) > > > +{ > > [] > > > + /* Applying a new frequency can take up to 10ms */ > > > + usleep_range(10000, 10000); > >=20 > > Generally it's nicer to have an actual range for usleep_range. > Well, as I said in the discussion with Guenther. I'm flexible and nob= ody > objected when I said to make both equal. A real range doesn't make se= nse > here though, but I don't know what's common practice for cases like > this. udelay is normal, but I guess you don't need atomic context. =20 > > Is there a bit you could periodically poll to see > > if the new frequency has been set or is stable so > > that a 10ms delay isn't always used? > Unfortunately not. Thanks. I suppose I should read the datasheets before asking. http://www.silabs.com/Support%20Documents/TechnicalDocs/si570.pdf (page 12) Anyway, perhaps si570_set_frequency_small needs a delay too.' The 570 datasheet says it needs a 100uS delay. > On Wed, 2013-09-18 at 15:43 -0700, Soren Brinkmann wrote: > Add a driver for SILabs 570, 571, 598, 599 programmable oscillators. > The devices generate low-jitter clock signals and are reprogrammable = via > an I2C interface. > [] > +static int si570_set_frequency_small(struct clk_si570 *data, > + unsigned long frequency) > +{ > + /* > + * This is a re-implementation of DIV_ROUND_CLOSEST > + * using the div64_u64 function lieu of letting the compiler > + * insert EABI calls > + */ > + data->rfreq =3D div64_u64((data->rfreq * frequency) + > + div_u64(data->frequency, 2), data->frequency); > + regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_FREEZE_M)= ; > + si570_update_rfreq(data); > + regmap_write(data->regmap, SI570_REG_CONTROL, 0); > + > + return 0; > +} -- To unsubscribe from this list: send the line "unsubscribe devicetree" i= n the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html