Change in coreboot[master]: mb/siemens/mc_apl{1,2,3,5,6}: Tune I2C frequency

[Patrick Georgi (Code Review)]

Patrick Georgi has submitted this change. ( https://review.coreboot.org/c/coreboot/+/52721 )

Change subject: mb/siemens/mc_apl{1,2,3,5,6}: Tune I2C frequency
......................................................................

mb/siemens/mc_apl{1,2,3,5,6}: Tune I2C frequency

All the boards in the patch have a constraint for the I2C bus to operate
on 100 kHz. Provide dedicated values for rise time, fall time and data
hold time on mainboard level to get a proper timing which takes the bus
load into account. Giving these values the driver computes the needed
timings correctly.

TEST=Measure I2C frequency on all boards while coreboot accesses
external RTC and make sure it is 100 kHz.

Change-Id: Iab634190bda5fa2a4fdf2ebaa1e45ac897d84deb
Signed-off-by: Werner Zeh 
Reviewed-on: https://review.coreboot.org/c/coreboot/+/52721
Reviewed-by: Mario Scheithauer 
Reviewed-by: Furquan Shaikh 
Reviewed-by: Kyösti Mälkki 
Tested-by: build bot (Jenkins) 
---
M src/mainboard/siemens/mc_apl1/variants/mc_apl1/devicetree.cb
M src/mainboard/siemens/mc_apl1/variants/mc_apl2/devicetree.cb
M src/mainboard/siemens/mc_apl1/variants/mc_apl3/devicetree.cb
M src/mainboard/siemens/mc_apl1/variants/mc_apl5/devicetree.cb
M src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb
5 files changed, 44 insertions(+), 1 deletion(-)

Approvals:
  build bot (Jenkins): Verified
  Kyösti Mälkki: Looks good to me, but someone else must approve
  Furquan Shaikh: Looks good to me, approved
  Mario Scheithauer: Looks good to me, approved

diff --git a/src/mainboard/siemens/mc_apl1/variants/mc_apl1/devicetree.cb b/src/mainboard/siemens/mc_apl1/variants/mc_apl1/devicetree.cb
index 92b4e7c..b7590fa 100644
--- a/src/mainboard/siemens/mc_apl1/variants/mc_apl1/devicetree.cb
+++ b/src/mainboard/siemens/mc_apl1/variants/mc_apl1/devicetree.cb
@@ -46,7 +46,10 @@
    #+-------------------+---------------------------+
    register "common_soc_config" = "{
    	.i2c[0] = {
-			.speed = I2C_SPEED_STANDARD
+			.speed = I2C_SPEED_STANDARD,
+			.rise_time_ns = 160,
+			.fall_time_ns = 110,
+			.data_hold_time_ns = 300
    	},
    }"

diff --git a/src/mainboard/siemens/mc_apl1/variants/mc_apl2/devicetree.cb b/src/mainboard/siemens/mc_apl1/variants/mc_apl2/devicetree.cb
index bc70674..336d6c4 100644
--- a/src/mainboard/siemens/mc_apl1/variants/mc_apl2/devicetree.cb
+++ b/src/mainboard/siemens/mc_apl1/variants/mc_apl2/devicetree.cb
@@ -41,6 +41,16 @@
    # Enable Vtd feature
    register "enable_vtd" = "1"

+	# I2C3 controller used for RTC
+	register "common_soc_config" = "{
+		.i2c[3] = {
+			.speed = I2C_SPEED_STANDARD,
+			.rise_time_ns = 60,
+			.fall_time_ns = 20,
+			.data_hold_time_ns = 300
+		},
+	}"
+
    device domain 0 on
    	device pci 00.0 on  end	# - Host Bridge
    	device pci 00.1 off end	# - DPTF
diff --git a/src/mainboard/siemens/mc_apl1/variants/mc_apl3/devicetree.cb b/src/mainboard/siemens/mc_apl1/variants/mc_apl3/devicetree.cb
index 66ff911..635ff3f 100644
--- a/src/mainboard/siemens/mc_apl1/variants/mc_apl3/devicetree.cb
+++ b/src/mainboard/siemens/mc_apl1/variants/mc_apl3/devicetree.cb
@@ -38,6 +38,16 @@
    # 0:HS400(Default), 1:HS200, 2:DDR50
    register "emmc_host_max_speed" = "1"

+	# I2C0 controller used for RTC
+	register "common_soc_config" = "{
+		.i2c[0] = {
+			.speed = I2C_SPEED_STANDARD,
+			.rise_time_ns = 40,
+			.fall_time_ns = 10,
+			.data_hold_time_ns = 300
+		},
+	}"
+
    device domain 0 on
    	device pci 00.0 on  end	# - Host Bridge
    	device pci 00.1 off end	# - DPTF
diff --git a/src/mainboard/siemens/mc_apl1/variants/mc_apl5/devicetree.cb b/src/mainboard/siemens/mc_apl1/variants/mc_apl5/devicetree.cb
index 5d288c0..48b4ad8 100644
--- a/src/mainboard/siemens/mc_apl1/variants/mc_apl5/devicetree.cb
+++ b/src/mainboard/siemens/mc_apl1/variants/mc_apl5/devicetree.cb
@@ -41,6 +41,16 @@
    # Enable Vtd feature
    register "enable_vtd" = "1"

+	# I2C0 controller used for RTC
+	register "common_soc_config" = "{
+		.i2c[0] = {
+			.speed = I2C_SPEED_STANDARD,
+			.rise_time_ns = 160,
+			.fall_time_ns = 110,
+			.data_hold_time_ns = 300
+		},
+	}"
+
    device domain 0 on
    	device pci 00.0 on  end	# - Host Bridge
    	device pci 00.1 off end	# - DPTF
diff --git a/src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb b/src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb
index 9c1054a..e2a3ea0 100644
--- a/src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb
+++ b/src/mainboard/siemens/mc_apl1/variants/mc_apl6/devicetree.cb
@@ -12,6 +12,16 @@
    # Enable Vtd feature
    register "enable_vtd" = "1"

+	# I2C0 controller used for RTC
+	register "common_soc_config" = "{
+		.i2c[0] = {
+			.speed = I2C_SPEED_STANDARD,
+			.rise_time_ns = 40,
+			.fall_time_ns = 10,
+			.data_hold_time_ns = 300
+		}
+	}"
+
    device domain 0 on
    	device pci 00.0 on  end	# - Host Bridge
    	device pci 00.1 off end	# - DPTF