linux-kernel - [PATCH] i2c: designware-platdrv: get fast/std speed scl high/low count from DT

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Date:	Wed, 6 Apr 2016 15:28:00 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	<wsa@...-dreams.de>, <robh+dt@...nel.org>, <pawel.moll@....com>,
	<mark.rutland@....com>, <ijc+devicetree@...lion.org.uk>,
	<galak@...eaurora.org>, <jarkko.nikula@...ux.intel.com>,
	<andriy.shevchenko@...ux.intel.com>,
	<mika.westerberg@...ux.intel.com>
CC:	<linux-i2c@...r.kernel.org>, <devicetree@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	Jisheng Zhang <jszhang@...vell.com>
Subject: [PATCH] i2c: designware-platdrv: get fast/std speed scl high/low count from DT

Sometimes, it's convenient to define the scl's high/low count directly,
e.g HW people would do some measurement then directly give out the
optimum counts. Previously, we solved the sda falling time and scl
falling time by i2c_dw_scl_hcnt() and i2c_dw_scl_lcnt(), then put them
into dt, but what we really care isn't the sda/scl falling time.

>From another side, the dw_i2c_acpi_configure() on ACPI platform also
get hcnt/lcnt values rather than the sda/scl falling time from ACPI
method, we want similar feature for DT platforms.

Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
---
 Documentation/devicetree/bindings/i2c/i2c-designware.txt | 16 ++++++++++++++++
 drivers/i2c/busses/i2c-designware-platdrv.c              |  8 ++++++++
 2 files changed, 24 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-designware.txt b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
index fee26dc..05176fbf 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-designware.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-designware.txt
@@ -20,6 +20,22 @@ Optional properties :
  - i2c-sda-falling-time-ns : should contain the SDA falling time in nanoseconds.
    This value which is by default 300ns is used to compute the tHIGH period.
 
+ - i2c-ss-scl-high-count : should contain the standard speed i2c clock SCL high
+   count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns
+   will be ignored.
+
+ - i2c-ss-scl-low-count : should contain the standard speed i2c clock SCL low
+   count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns
+   will be ignored.
+
+ - i2c-fs-scl-high-count : should contain the fast speed i2c clock SCL high
+   count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns
+   will be ignored.
+
+ - i2c-fs-scl-low-count : should contain the fast speed i2c clock SCL low
+   count. If defined, the i2c-scl-falling-time-ns and i2c-sda-falling-time-ns
+   will be ignored.
+
 Example :
 
 	i2c@...00 {
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index d656657..8739a60 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -188,6 +188,14 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 					 &dev->scl_falling_time);
 		device_property_read_u32(&pdev->dev, "clock-frequency",
 					 &clk_freq);
+		device_property_read_u16(&pdev->dev, "i2c-ss-scl-high-count",
+					 &dev->ss_hcnt);
+		device_property_read_u16(&pdev->dev, "i2c-ss-scl-low-count",
+					 &dev->ss_lcnt);
+		device_property_read_u16(&pdev->dev, "i2c-fs-scl-high-count",
+					 &dev->fs_hcnt);
+		device_property_read_u16(&pdev->dev, "i2c-fs-scl-low-count",
+					 &dev->fs_lcnt);
 	}
 
 	if (has_acpi_companion(&pdev->dev))
-- 
2.8.0.rc3