From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mika Westerberg Subject: [PATCH] i2c-designware: configure SDA hold time from ACPI Date: Wed, 3 Jul 2013 12:52:40 +0300 Message-ID: <1372845160-32625-1-git-send-email-mika.westerberg@linux.intel.com> Return-path: Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: Wolfram Sang , Christian Ruppert , Mika Westerberg , linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-i2c@vger.kernel.org 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 --- 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 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; } -- 1.8.3.2