From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sekhar Nori Subject: Re: [PATCH] i2c: davinci: Fix bus rate calculation on Keystone SoC Date: Thu, 18 Jun 2015 14:30:32 +0530 Message-ID: <558288B0.1020706@ti.com> References: <5582870B.7030304@nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <5582870B.7030304-xNZwKgViW5gAvxtiuMwx3w@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Alexander Sverdlin , Kevin Hilman , Wolfram Sang , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Murali Karicheri List-Id: linux-i2c@vger.kernel.org On Thursday 18 June 2015 02:23 PM, Alexander Sverdlin wrote: > According to KeyStone Architecture I2C User Guide, > > module clock frequency > master clock frequency = ---------------------- > (ICCL + 6) + (ICCH + 6) > > i.e. "d" in i2c_davinci_calc_clk_dividers() should be fixed and > not dependent from module clock prescaler PSC on these SoCs. > > Signed-off-by: Alexander Sverdlin > --- > > RFC: If someone from TI has an idea how to improve the coverage of future Keystone > revisions -- hints/patches are welcome. The current ID check is based on > Davinci/Keystone datasheets and is at least working on real Keystone II. + Murali who works on Keystone devices in TI. > > drivers/i2c/busses/i2c-davinci.c | 10 ++++++++++ > 1 files changed, 10 insertions(+), 0 deletions(-) > > diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c > index 4a110af..3d78f6a 100644 > --- a/drivers/i2c/busses/i2c-davinci.c > +++ b/drivers/i2c/busses/i2c-davinci.c > @@ -60,6 +60,8 @@ > #define DAVINCI_I2C_IVR_REG 0x28 > #define DAVINCI_I2C_EMDR_REG 0x2c > #define DAVINCI_I2C_PSC_REG 0x30 > +#define DAVINCI_I2C_ICPID1_REG 0x34 > +#define DAVINCI_I2C_ICPID2_REG 0x38 > #define DAVINCI_I2C_FUNC_REG 0x48 > #define DAVINCI_I2C_DIR_REG 0x4c > #define DAVINCI_I2C_DIN_REG 0x50 > @@ -203,6 +205,9 @@ static void i2c_davinci_calc_clk_dividers(struct davinci_i2c_dev *dev) > * where if PSC == 0, d = 7, > * if PSC == 1, d = 6 > * if PSC > 1 , d = 5 > + * > + * Note: > + * d is always 6 on Keystone I2C controller > */ > > /* get minimum of 7 MHz clock, but max of 12 MHz */ > @@ -211,6 +216,11 @@ static void i2c_davinci_calc_clk_dividers(struct davinci_i2c_dev *dev) > psc++; /* better to run under spec than over */ > d = (psc >= 2) ? 5 : 7 - psc; > > + if (davinci_i2c_read_reg(dev, DAVINCI_I2C_ICPID2_REG) == 0x2206) { > + dev_dbg(dev->dev, "Keystone SoC detected\n"); > + d = 6; > + } I think its better to use a different compatible string for i2c on keystone devices rather than using a fixed hardcoded IP version. Thanks, Sekhar