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From: Vitor Soares <Vitor.Soares@synopsys.com>
To: linux-i3c@lists.infradead.org
Cc: Joao.Pinto@synopsys.com, Boris Brezillon <bbrezillon@kernel.org>,
	linux-kernel@vger.kernel.org,
	Vitor Soares <Vitor.Soares@synopsys.com>
Subject: [PATCH v3 2/3] i3c: add mixed limited bus mode
Date: Tue, 11 Jun 2019 16:06:44 +0200
Message-ID: <cdfdf31d1e52b7569f686c50e6f56163d21d8b36.1560261604.git.vitor.soares@synopsys.com> (raw)
In-Reply-To: <cover.1560261604.git.vitor.soares@synopsys.com>

The i3c bus spec defines a bus configuration where i2c devices don't
have a 50ns filter but support SCL running at SDR max rate (12.5MHz).

This patch introduces the limited bus mode so that users can use
a higher speed in presence of i2c devices index 1.

Signed-off-by: Vitor Soares <vitor.soares@synopsys.com>
Cc: Boris Brezillon <bbrezillon@kernel.org>
Cc: <linux-kernel@vger.kernel.org>
---
Changes in v3:
  None

Changes in v2:
  Enhance commit message

 drivers/i3c/master.c       | 5 +++++
 include/linux/i3c/master.h | 5 +++++
 2 files changed, 10 insertions(+)

diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c
index f8e580e..025925c 100644
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -470,6 +470,7 @@ static int i3c_bus_init(struct i3c_bus *i3cbus)
 static const char * const i3c_bus_mode_strings[] = {
 	[I3C_BUS_MODE_PURE] = "pure",
 	[I3C_BUS_MODE_MIXED_FAST] = "mixed-fast",
+	[I3C_BUS_MODE_MIXED_LIMITED] = "mixed-limited",
 	[I3C_BUS_MODE_MIXED_SLOW] = "mixed-slow",
 };
 
@@ -585,6 +586,7 @@ int i3c_bus_set_mode(struct i3c_bus *i3cbus, enum i3c_bus_mode mode,
 			i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
 		break;
 	case I3C_BUS_MODE_MIXED_FAST:
+	case I3C_BUS_MODE_MIXED_LIMITED:
 		if (!i3cbus->scl_rate.i3c)
 			i3cbus->scl_rate.i3c = I3C_BUS_TYP_I3C_SCL_RATE;
 		if (!i3cbus->scl_rate.i2c)
@@ -2490,6 +2492,9 @@ int i3c_master_register(struct i3c_master_controller *master,
 				mode = I3C_BUS_MODE_MIXED_FAST;
 			break;
 		case I3C_LVR_I2C_INDEX(1):
+			if (mode < I3C_BUS_MODE_MIXED_LIMITED)
+				mode = I3C_BUS_MODE_MIXED_LIMITED;
+			break;
 		case I3C_LVR_I2C_INDEX(2):
 			if (mode < I3C_BUS_MODE_MIXED_SLOW)
 				mode = I3C_BUS_MODE_MIXED_SLOW;
diff --git a/include/linux/i3c/master.h b/include/linux/i3c/master.h
index f13fd8b..89ea461 100644
--- a/include/linux/i3c/master.h
+++ b/include/linux/i3c/master.h
@@ -250,12 +250,17 @@ struct i3c_device {
  *			     the bus. The only impact in this mode is that the
  *			     high SCL pulse has to stay below 50ns to trick I2C
  *			     devices when transmitting I3C frames
+ * @I3C_BUS_MODE_MIXED_LIMITED: I2C devices without 50ns spike filter are
+ *				present on the bus. However they allows
+ *				compliance up to the maximum SDR SCL clock
+ *				frequency.
  * @I3C_BUS_MODE_MIXED_SLOW: I2C devices without 50ns spike filter are present
  *			     on the bus
  */
 enum i3c_bus_mode {
 	I3C_BUS_MODE_PURE,
 	I3C_BUS_MODE_MIXED_FAST,
+	I3C_BUS_MODE_MIXED_LIMITED,
 	I3C_BUS_MODE_MIXED_SLOW,
 };
 
-- 
2.7.4


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  parent reply index

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-06-11 14:06 [PATCH v3 0/3] Fix i2c and i3c scl rate according " Vitor Soares
2019-06-11 14:06 ` [PATCH v3 1/3] i3c: fix i2c and i3c scl rate by " Vitor Soares
2019-06-12  6:15   ` Boris Brezillon
2019-06-12 11:16     ` Vitor Soares
2019-06-12 11:37       ` Boris Brezillon
2019-06-12 13:37         ` Vitor Soares
2019-06-12 14:20           ` Boris Brezillon
2019-06-11 14:06 ` Vitor Soares [this message]
2019-06-11 14:06 ` [PATCH v3 3/3] i3c: dw: add limited bus mode support Vitor Soares

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