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From c8d4cf878f12987c7fda5ac6bfe85168a24dc40a Mon Sep 17 00:00:00 2001
From: Alistair Buxton <a.j.buxton@gmail.com>
Date: Sun, 1 Nov 2015 22:27:56 +0000
Subject: [PATCH] Build i2c_gpio module and add a device tree overlay to
configure it.
---
arch/arm/boot/dts/overlays/Makefile | 1 +
arch/arm/boot/dts/overlays/README | 13 +++++++++++-
arch/arm/boot/dts/overlays/i2c-gpio-overlay.dts | 28 +++++++++++++++++++++++++
arch/arm/configs/bcm2709_defconfig | 1 +
arch/arm/configs/bcmrpi_defconfig | 1 +
5 files changed, 43 insertions(+), 1 deletion(-)
create mode 100644 arch/arm/boot/dts/overlays/i2c-gpio-overlay.dts
--- a/arch/arm/boot/dts/overlays/Makefile
+++ b/arch/arm/boot/dts/overlays/Makefile
@@ -25,6 +25,7 @@ dtb-$(RPI_DT_OVERLAYS) += hifiberry-digi
dtb-$(RPI_DT_OVERLAYS) += hy28a-overlay.dtb
dtb-$(RPI_DT_OVERLAYS) += hy28b-overlay.dtb
dtb-$(RPI_DT_OVERLAYS) += i2c-rtc-overlay.dtb
+dtb-$(RPI_DT_OVERLAYS) += i2c-gpio-overlay.dtb
dtb-$(RPI_DT_OVERLAYS) += i2s-mmap-overlay.dtb
dtb-$(RPI_DT_OVERLAYS) += iqaudio-dac-overlay.dtb
dtb-$(RPI_DT_OVERLAYS) += iqaudio-dacplus-overlay.dtb
--- a/arch/arm/boot/dts/overlays/README
+++ b/arch/arm/boot/dts/overlays/README
@@ -287,9 +287,20 @@ Params: speed Display
ledgpio GPIO used to control backlight
+Name: i2c-gpio
+Info: Adds support for software i2c controller on gpio pins
+Load: dtoverlay=i2c-gpio,<param>=<val>
+Params: i2c_gpio_sda GPIO used for I2C data (default "23")
+
+ i2c_gpio_scl GPIO used for I2C clock (default "24")
+
+ i2c_gpio_delay_us Clock delay in microseconds
+ (default "2" = ~100kHz)
+
+
Name: i2c-rtc
Info: Adds support for a number of I2C Real Time Clock devices
-Load: dtoverlay=i2c-rtc,<param>
+Load: dtoverlay=i2c-rtc,<param>=<val>
Params: ds1307 Select the DS1307 device
ds3231 Select the DS3231 device
--- /dev/null
+++ b/arch/arm/boot/dts/overlays/i2c-gpio-overlay.dts
@@ -0,0 +1,28 @@
+// Overlay for i2c_gpio bitbanging host bus.
+/dts-v1/;
+/plugin/;
+
+/ {
+ compatible = "brcm,bcm2708";
+
+ fragment@0 {
+ target-path = "/";
+ __overlay__ {
+ i2c_gpio: i2c@0 {
+ compatible = "i2c-gpio";
+ gpios = <&gpio 23 0 /* sda */
+ &gpio 24 0 /* scl */
+ >;
+ i2c-gpio,delay-us = <2>; /* ~100 kHz */
+ #address-cells = <1>;
+ #size-cells = <0>;
+ };
+ };
+ };
+ __overrides__ {
+ i2c_gpio_sda = <&i2c_gpio>,"gpios:4";
+ i2c_gpio_scl = <&i2c_gpio>,"gpios:16";
+ i2c_gpio_delay_us = <&i2c_gpio>,"i2c-gpio,delay-us:0";
+ };
+};
+
--- a/arch/arm/configs/bcm2709_defconfig
+++ b/arch/arm/configs/bcm2709_defconfig
@@ -595,6 +595,7 @@ CONFIG_RAW_DRIVER=y
CONFIG_I2C=y
CONFIG_I2C_CHARDEV=m
CONFIG_I2C_BCM2708=m
+CONFIG_I2C_GPIO=m
CONFIG_SPI=y
CONFIG_SPI_BCM2835=m
CONFIG_SPI_SPIDEV=y
--- a/arch/arm/configs/bcmrpi_defconfig
+++ b/arch/arm/configs/bcmrpi_defconfig
@@ -588,6 +588,7 @@ CONFIG_RAW_DRIVER=y
CONFIG_I2C=y
CONFIG_I2C_CHARDEV=m
CONFIG_I2C_BCM2708=m
+CONFIG_I2C_GPIO=m
CONFIG_SPI=y
CONFIG_SPI_BCM2835=m
CONFIG_SPI_SPIDEV=y
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