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i2c: designware: add support of I2C standard mode

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Some legacy devices support ony I2C standard mode at 100kHz.
This patch allows to select the standard mode through the DTS
with the use of the existing clock-frequency parameter.

When clock-frequency parameter is not set, the fast mode is selected.
Only when the parameter is set at 100000, the standard mode is selected.

Signed-off-by: Romain Baeriswyl <romainba@abilis.com>
Reviewed-by: Christian Ruppert <christian.ruppert@abilis.com>
Acked-by: Alan Tull <atull@opensource.altera.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
This commit is contained in:
Romain Baeriswyl 2014-08-20 16:29:08 +02:00 committed by Wolfram Sang
parent fe82dcec64
commit 8e5f6b2a28
1 changed files with 21 additions and 2 deletions
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23
drivers/i2c/busses/i2c-designware-platdrv.c
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@ -123,6 +123,7 @@ static int dw_i2c_probe(struct platform_device *pdev)
struct i2c_adapter *adap;
struct resource *mem;
int irq, r;
u32 clk_freq;
irq = platform_get_irq(pdev, 0);
if (irq < 0) {
@ -152,6 +153,9 @@ static int dw_i2c_probe(struct platform_device *pdev)
return PTR_ERR(dev->clk);
clk_prepare_enable(dev->clk);
/* fast mode by default because of legacy reasons */
clk_freq = 400000;
if (pdev->dev.of_node) {
u32 ht = 0;
u32 ic_clk = dev->get_clk_rate_khz(dev);
@ -167,6 +171,17 @@ 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);
of_property_read_u32(pdev->dev.of_node, "clock-frequency",
&clk_freq);
/* Only standard mode at 100kHz and fast mode at 400kHz
* are supported.
*/
if (clk_freq != 100000 && clk_freq != 400000) {
dev_err(&pdev->dev, "Only 100kHz and 400kHz supported");
return -EINVAL;
}
}
dev->functionality =
@ -176,8 +191,12 @@ static int dw_i2c_probe(struct platform_device *pdev)
I2C_FUNC_SMBUS_BYTE_DATA |
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;
if (clk_freq == 100000)
dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_STD;
else
dev->master_cfg = DW_IC_CON_MASTER | DW_IC_CON_SLAVE_DISABLE |
DW_IC_CON_RESTART_EN | DW_IC_CON_SPEED_FAST;
/* Try first if we can configure the device from ACPI */
r = dw_i2c_acpi_configure(pdev);