From mboxrd@z Thu Jan 1 00:00:00 1970 From: Uwe =?iso-8859-1?Q?Kleine-K=F6nig?= Subject: Re: [PATCH v8 2/3] I2C: mediatek: Add driver for MediaTek I2C controller Date: Mon, 18 May 2015 20:43:00 +0200 Message-ID: <20150518184300.GB28888@pengutronix.de> References: <1431967209-5261-1-git-send-email-eddie.huang@mediatek.com> <1431967209-5261-3-git-send-email-eddie.huang@mediatek.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <1431967209-5261-3-git-send-email-eddie.huang-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org> Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Eddie Huang Cc: Wolfram Sang , srv_heupstream-NuS5LvNUpcJWk0Htik3J/w@public.gmane.org, Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Matthias Brugger , Xudong Chen , Liguo Zhang , linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-mediatek-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Sascha Hauer List-Id: devicetree@vger.kernel.org Hello, On Tue, May 19, 2015 at 12:40:08AM +0800, Eddie Huang wrote: > From: Xudong Chen >=20 > The mediatek SoCs have I2C controller that handle I2C transfer. > This patch include common I2C bus driver. > This driver is compatible with I2C controller on mt65xx/mt81xx. >=20 > Signed-off-by: Xudong Chen > Signed-off-by: Liguo Zhang > Signed-off-by: Eddie Huang > Acked-by: Sascha Hauer > --- > drivers/i2c/busses/Kconfig | 9 + > drivers/i2c/busses/Makefile | 1 + > drivers/i2c/busses/i2c-mt65xx.c | 675 ++++++++++++++++++++++++++++++= ++++++++++ > 3 files changed, 685 insertions(+) > create mode 100644 drivers/i2c/busses/i2c-mt65xx.c >=20 > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig > index 2255af2..14c7266 100644 > --- a/drivers/i2c/busses/Kconfig > +++ b/drivers/i2c/busses/Kconfig > @@ -620,6 +620,15 @@ config I2C_MPC > This driver can also be built as a module. If so, the module > will be called i2c-mpc. > =20 > +config I2C_MT65XX > + tristate "MediaTek I2C adapter" > + depends on ARCH_MEDIATEK || COMPILE_TEST > + help > + This selects the MediaTek(R) Integrated Inter Circuit bus driver > + for MT65xx and MT81xx. > + If you want to use MediaTek(R) I2C interface, say Y or M here. > + If unsure, say N. > + > config I2C_MV64XXX > tristate "Marvell mv64xxx I2C Controller" > depends on MV64X60 || PLAT_ORION || ARCH_SUNXI > diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefil= e > index cdf941d..abbf422 100644 > --- a/drivers/i2c/busses/Makefile > +++ b/drivers/i2c/busses/Makefile > @@ -60,6 +60,7 @@ obj-$(CONFIG_I2C_JZ4780) +=3D i2c-jz4780.o > obj-$(CONFIG_I2C_KEMPLD) +=3D i2c-kempld.o > obj-$(CONFIG_I2C_MESON) +=3D i2c-meson.o > obj-$(CONFIG_I2C_MPC) +=3D i2c-mpc.o > +obj-$(CONFIG_I2C_MT65XX) +=3D i2c-mt65xx.o > obj-$(CONFIG_I2C_MV64XXX) +=3D i2c-mv64xxx.o > obj-$(CONFIG_I2C_MXS) +=3D i2c-mxs.o > obj-$(CONFIG_I2C_NOMADIK) +=3D i2c-nomadik.o > diff --git a/drivers/i2c/busses/i2c-mt65xx.c b/drivers/i2c/busses/i2c= -mt65xx.c > new file mode 100644 > index 0000000..7462f05 > --- /dev/null > +++ b/drivers/i2c/busses/i2c-mt65xx.c > @@ -0,0 +1,675 @@ > +/* > + * Copyright (c) 2014 MediaTek Inc. > + * Author: Xudong.chen s/Xudong.chen/Xudong Chen/ > +#define I2C_DRV_NAME "mt-i2c" i2c-mt65xx ? > +} > + > +/* calculate i2c port speed */ It would be nice to summarize the clock frequency settings here. Something like: /* * The input clock is divided by the value specified in the * device tree as clock-div. The actual bus speed is then * derived from this frequency by the following formula: * .... This would make it possible to verify your calculations below. > +static int mtk_i2c_set_speed(struct mtk_i2c *i2c, unsigned int clk_s= rc_in_hz) > +{ > + unsigned int khz; > + unsigned int step_cnt; > + unsigned int sample_cnt; > + unsigned int sclk; > + unsigned int hclk; > + unsigned int max_step_cnt; > + unsigned int sample_div =3D MAX_SAMPLE_CNT_DIV; > + unsigned int step_div; > + unsigned int min_div; > + unsigned int best_mul; > + unsigned int cnt_mul; > + > + if (i2c->speed_hz > MAX_HS_MODE_SPEED) > + return -EINVAL; > + else if (i2c->speed_hz > MAX_FS_MODE_SPEED) > + max_step_cnt =3D MAX_HS_STEP_CNT_DIV; > + else > + max_step_cnt =3D MAX_STEP_CNT_DIV; > + > + step_div =3D max_step_cnt; > + /* Find the best combination */ > + khz =3D i2c->speed_hz / 1000; > + hclk =3D clk_src_in_hz / 1000; > + min_div =3D ((hclk >> 1) + khz - 1) / khz; This is DIV_ROUND_UP(hclk >> 1, khz). > + best_mul =3D MAX_SAMPLE_CNT_DIV * max_step_cnt; > + > + for (sample_cnt =3D 1; sample_cnt <=3D MAX_SAMPLE_CNT_DIV; sample_c= nt++) { > + step_cnt =3D (min_div + sample_cnt - 1) / sample_cnt; > + cnt_mul =3D step_cnt * sample_cnt; > + if (step_cnt > max_step_cnt) > + continue; > + > + if (cnt_mul < best_mul) { > + best_mul =3D cnt_mul; > + sample_div =3D sample_cnt; > + step_div =3D step_cnt; > + if (best_mul =3D=3D min_div) > + break; > + } > + } > + > + sample_cnt =3D sample_div; > + step_cnt =3D step_div; > + sclk =3D hclk / (2 * sample_cnt * step_cnt); > + if (sclk > khz) { > + dev_dbg(i2c->dev, "%s mode: unsupported speed (%ldkhz)\n", > + (i2c->speed_hz > MAX_HS_MODE_SPEED) ? "HS" : "ST/FT", > + (long int)khz); > + return -EINVAL; > + } > + > + step_cnt--; > + sample_cnt--; > + > + if (i2c->speed_hz > MAX_FS_MODE_SPEED) { > + /* Set the hign speed mode register */ > + i2c->timing_reg =3D I2C_FS_TIME_INIT_VALUE; > + i2c->high_speed_reg =3D I2C_TIME_DEFAULT_VALUE | > + (sample_cnt & I2C_TIMING_SAMPLE_COUNT_MASK) << 12 | > + (step_cnt & I2C_TIMING_SAMPLE_COUNT_MASK) << 8; > + } else { > + i2c->timing_reg =3D > + (sample_cnt & I2C_TIMING_SAMPLE_COUNT_MASK) << 8 | > + (step_cnt & I2C_TIMING_STEP_DIV_MASK) << 0; > + /* Disable the high speed transaction */ > + i2c->high_speed_reg =3D I2C_TIME_CLR_VALUE; Can it happen that sample_cnt & I2C_TIMING_SAMPLE_COUNT_MASK !=3D sample_cnt? If yes, what is the influence on correctness? Same question for step_cnt. Best regards Uwe --=20 Pengutronix e.K. | Uwe Kleine-K=F6nig = | Industrial Linux Solutions | http://www.pengutronix.de/= |