From 42c681b8e6478c20dd2a529698c25906ca222784 Mon Sep 17 00:00:00 2001 From: Liviu Dudau Date: Fri, 3 Oct 2014 10:33:21 +0100 Subject: [PATCH] i2c: designware: Add support for changing the bus rate based on DT info The Designware I2C driver does not currently support changing the bus speed even if the hardware is capable of switching to a slower frequency. Add support for passing the clock frequency info in the device tree. Only standard (100kHz) or fast (400kHz) speeds are supported. Signed-off-by: Andrew Jackson Signed-off-by: Liviu Dudau --- drivers/i2c/busses/i2c-designware-platdrv.c | 19 ++++++++++++++++++- 1 file changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c index 9c78026..bcec19f 100644 --- a/drivers/i2c/busses/i2c-designware-platdrv.c +++ b/drivers/i2c/busses/i2c-designware-platdrv.c @@ -122,6 +122,7 @@ static int dw_i2c_probe(struct platform_device *pdev) struct i2c_adapter *adap; struct resource *mem; int irq, r; + u32 bus_rate = DW_IC_CON_SPEED_STD; irq = platform_get_irq(pdev, 0); if (irq < 0) { @@ -166,6 +167,22 @@ 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); + + r = of_property_read_u32(pdev->dev.of_node, "clock-frequency", + &bus_rate); + if (r) + bus_rate = 400000; /* default clock rate */ + switch (bus_rate) { + case 400000: + bus_rate = DW_IC_CON_SPEED_FAST; + break; + case 100000: + bus_rate = DW_IC_CON_SPEED_STD; + break; + default: + dev_err(&pdev->dev, "Invalid bus speed (not 100kHz or 400kHz)\n"); + return -EINVAL; + } } dev->functionality = @@ -176,7 +193,7 @@ 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 | bus_rate; /* Try first if we can configure the device from ACPI */ r = dw_i2c_acpi_configure(pdev); -- 2.7.4