i2c-designware: configure SDA hold time from ACPI

Submitted by Mika Westerberg on July 3, 2013, 9:52 a.m.

Details

Message ID 1372845160-32625-1-git-send-email-mika.westerberg@linux.intel.com
State Superseded
Headers show

Commit Message

Mika Westerberg July 3, 2013, 9:52 a.m.
Some Intel LPSS I2C devices make the SDA hold time parameter available via
SSCN (standard mode) and FMCN (fast mode) ACPI methods. If we find that
such method exist, we evaluate it and pass the returned SDA hold value to
the i2c-designware core analogous to Device Tree.

Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-platdrv.c | 19 ++++++++++++++++++-
 1 file changed, 18 insertions(+), 1 deletion(-)

Comments

Mika Westerberg July 10, 2013, 2:20 p.m.
On Wed, Jul 03, 2013 at 12:52:40PM +0300, Mika Westerberg wrote:
> Some Intel LPSS I2C devices make the SDA hold time parameter available via
> SSCN (standard mode) and FMCN (fast mode) ACPI methods. If we find that
> such method exist, we evaluate it and pass the returned SDA hold value to
> the i2c-designware core analogous to Device Tree.
> 
> Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>

Please disregard this patch. I'll send a new one that combines both setting of
SDA hold time and *CNT values from ACPI.
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Patch hide | download patch | download mbox

diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 8b9d3f1..c7cfdac 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -57,13 +57,30 @@  static u32 i2c_dw_get_clk_rate_khz(struct dw_i2c_dev *dev)
 static int dw_i2c_acpi_configure(struct platform_device *pdev)
 {
 	struct dw_i2c_dev *dev = platform_get_drvdata(pdev);
+	struct acpi_buffer buf = { ACPI_ALLOCATE_BUFFER };
+	acpi_handle handle = ACPI_HANDLE(&pdev->dev);
+	acpi_string name;
 
-	if (!ACPI_HANDLE(&pdev->dev))
+	if (!handle)
 		return -ENODEV;
 
 	dev->adapter.nr = -1;
 	dev->tx_fifo_depth = 32;
 	dev->rx_fifo_depth = 32;
+
+	name = dev->master_cfg & DW_IC_CON_SPEED_FAST ? "FMCN" : "SSCN";
+	if (ACPI_SUCCESS(acpi_evaluate_object(handle, name, NULL, &buf))) {
+		union acpi_object *obj = (union acpi_object *)buf.pointer;
+
+		if (obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 3) {
+			const union acpi_object *objs = obj->package.elements;
+
+			dev->sda_hold_time = (u32)objs[2].integer.value;
+		}
+
+		kfree(buf.pointer);
+	}
+
 	return 0;
 }