linux-kernel - [PATCH v3 3/9] i2c: add support for filter-width-ns optional property

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Date:   Tue, 9 Jul 2019 13:19:36 +0000
From:   <Eugen.Hristev@...rochip.com>
To:     <wsa@...-dreams.de>, <peda@...ntia.se>, <mark.rutland@....com>,
        <Ludovic.Desroches@...rochip.com>, <linux-i2c@...r.kernel.org>,
        <devicetree@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        <linux-kernel@...r.kernel.org>, <pierre-yves.mordret@...com>,
        <alexandre.belloni@...tlin.com>, <robh+dt@...nel.org>
CC:     <Nicolas.Ferre@...rochip.com>, <Eugen.Hristev@...rochip.com>
Subject: [PATCH v3 3/9] i2c: add support for filter-width-ns optional property

From: Eugen Hristev <eugen.hristev@...rochip.com>

This optional timing property specifies the width of the spikes on the i2c
lines (in ns) that can be filtered out by built-in analog or digital filters
which are embedded in some i2c controllers.
Include it in the timings structure and read it as integer property.

Signed-off-by: Eugen Hristev <eugen.hristev@...rochip.com>
---
 drivers/i2c/i2c-core-base.c | 2 ++
 include/linux/i2c.h         | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 9e43508..73d1c62 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1658,6 +1658,8 @@ void i2c_parse_fw_timings(struct device *dev, struct i2c_timings *t, bool use_de
 		t->sda_fall_ns = t->scl_fall_ns;
 
 	device_property_read_u32(dev, "i2c-sda-hold-time-ns", &t->sda_hold_ns);
+
+	device_property_read_u32(dev, "i2c-filter-width-ns", &t->filter_width_ns);
 }
 EXPORT_SYMBOL_GPL(i2c_parse_fw_timings);
 
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index 1308126..dfb6525 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -563,6 +563,7 @@ struct i2c_lock_operations {
  * @scl_int_delay_ns: time IP core additionally needs to setup SCL in ns
  * @sda_fall_ns: time SDA signal takes to fall in ns; t(f) in the I2C specification
  * @sda_hold_ns: time IP core additionally needs to hold SDA in ns
+ * @filter_width_ns: width in ns of spikes on i2c lines that the IP core can filter out
  */
 struct i2c_timings {
 	u32 bus_freq_hz;
@@ -571,6 +572,7 @@ struct i2c_timings {
 	u32 scl_int_delay_ns;
 	u32 sda_fall_ns;
 	u32 sda_hold_ns;
+	u32 filter_width_ns;
 };
 
 /**
-- 
2.7.4