From mboxrd@z Thu Jan 1 00:00:00 1970 From: Subject: [PATCH] i2c: designware: deduce speed mode from device tree setting Date: Tue, 19 Aug 2014 15:18:49 -0500 Message-ID: <1408479529-24249-1-git-send-email-atull@opensource.altera.com> Mime-Version: 1.0 Content-Type: text/plain Return-path: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org, baruch-NswTu9S1W3P6gbPvEgmw2w@public.gmane.org, mika.westerberg-VuQAYsv1563Yd54FQh9/CA@public.gmane.org Cc: grant.likely-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, skuribay-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org, Romain.Baeriswyl-ux6zf3SgZrrQT0dZR+AlfA@public.gmane.org, rafael.j.wysocki-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, alan-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, delicious.quinoa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, dinguyen-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org, yvanderv-yzvPICuk2ABMcg4IHK0kFoH6Mc4MB0Vx@public.gmane.org, Alan Tull List-Id: devicetree@vger.kernel.org From: Alan Tull Use the documented, but unimplemented "clock-frequency" Device Tree setting as a guide on whether to set the speed mode bits in DW_IC_CON to standard or fast i2c mode. Previously, the driver was hardwired to fast mode. Default to fast mode if the "clock-frequency" property is not present for backwards compatiblity. Signed-off-by: Alan Tull --- drivers/i2c/busses/i2c-designware-platdrv.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c index bc87733..18cd3d9 100644 --- a/drivers/i2c/busses/i2c-designware-platdrv.c +++ b/drivers/i2c/busses/i2c-designware-platdrv.c @@ -122,7 +122,8 @@ static int dw_i2c_probe(struct platform_device *pdev) struct dw_i2c_dev *dev; struct i2c_adapter *adap; struct resource *mem; - int irq, r; + int irq, r, ret, speed = DW_IC_CON_SPEED_FAST; + u32 bus_rate; irq = platform_get_irq(pdev, 0); if (irq < 0) { @@ -167,6 +168,11 @@ static int dw_i2c_probe(struct platform_device *pdev) of_property_read_u32(pdev->dev.of_node, "i2c-scl-falling-time-ns", &dev->scl_falling_time); + + ret = of_property_read_u32(pdev->dev.of_node, + "clock-frequency", &bus_rate); + if (!ret && (bus_rate <= 100000)) + speed = DW_IC_CON_SPEED_STD; } dev->functionality = @@ -177,7 +183,7 @@ static int dw_i2c_probe(struct platform_device *pdev) I2C_FUNC_SMBUS_WORD_DATA | I2C_FUNC_SMBUS_I2C_BLOCK; dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE | - DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST; + DW_IC_CON_RESTART_EN | speed; /* Try first if we can configure the device from ACPI */ r = dw_i2c_acpi_configure(pdev); -- 1.7.9.5