96boards · koenkooi · Apr 15, 2015 · Mar 27, 2015 · Mar 27, 2015 · Mar 29, 2015
diff --git a/Documentation/devicetree/bindings/i2c/i2c-davinci.txt b/Documentation/devicetree/bindings/i2c/i2c-davinci.txt
@@ -10,6 +10,9 @@ Required properties:
 Recommended properties :
 - interrupts : standard interrupt property.
 - clock-frequency : desired I2C bus clock frequency in Hz.
+- ti,has-pfunc: boolean; if defined, it indicates that SoC supports PFUNC
+	registers. PFUNC registers allow to switch I2C pins to function as
+	GPIOs, so they can by toggled manually.
 
 Example (enbw_cmc board):
 	i2c@1c22000 {

diff --git a/Documentation/devicetree/bindings/i2c/i2c-digicolor.txt b/Documentation/devicetree/bindings/i2c/i2c-digicolor.txt
@@ -0,0 +1,25 @@
+Conexant Digicolor I2C controller
+
+Required properties:
+ - compatible: must be "cnxt,cx92755-i2c"
+ - reg: physical address and length of the device registers
+ - interrupts: a single interrupt specifier
+ - clocks: clock for the device
+ - #address-cells: should be <1>
+ - #size-cells: should be <0>
+
+Optional properties:
+- clock-frequency: the desired I2C bus clock frequency in Hz; in
+  absence of this property the default value is used (100 kHz).
+
+Example:
+
+	i2c: i2c@f0000120 {
+		compatible = "cnxt,cx92755-i2c";
+		reg = <0xf0000120 0x10>;
+		interrupts = <28>;
+		clocks = <&main_clk>;
+		clock-frequency = <100000>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+	};
diff --git a/Documentation/devicetree/bindings/i2c/i2c-jz4780.txt b/Documentation/devicetree/bindings/i2c/i2c-jz4780.txt
@@ -0,0 +1,35 @@
+* Ingenic JZ4780 I2C Bus controller
+
+Required properties:
+- compatible: should be "ingenic,jz4780-i2c"
+- reg: Should contain the address & size of the I2C controller registers.
+- interrupts: Should specify the interrupt provided by parent.
+- clocks: Should contain a single clock specifier for the JZ4780 I2C clock.
+- clock-frequency: desired I2C bus clock frequency in Hz.
+
+Recommended properties:
+- pinctrl-names: should be "default";
+- pinctrl-0: phandle to pinctrl function
+
+Optional properties:
+- interrupt-parent: Should be the phandle of the interrupt controller that
+  delivers interrupts to the I2C block.
+
+Example
+
+/ {
+	i2c4: i2c4@0x10054000 {
+		compatible = "ingenic,jz4780-i2c";
+		reg = <0x10054000 0x1000>;
+
+		interrupt-parent = <&intc>;
+		interrupts = <56>;
+
+		clocks = <&cgu JZ4780_CLK_SMB4>;
+		clock-frequency = <100000>;
+		pinctrl-names = "default";
+		pinctrl-0 = <&pins_i2c4_data>;
+
+	};
+};
+
diff --git a/Documentation/devicetree/bindings/i2c/i2c-xlp9xx.txt b/Documentation/devicetree/bindings/i2c/i2c-xlp9xx.txt
@@ -0,0 +1,22 @@
+Device tree configuration for the I2C controller on the XLP9xx/5xx SoC
+
+Required properties:
+- compatible      : should be "netlogic,xlp980-i2c"
+- reg             : bus address start and address range size of device
+- interrupts      : interrupt number
+
+Optional properties:
+- clock-frequency : frequency of bus clock in Hz
+                    Defaults to 100 KHz when the property is not specified
+
+Example:
+
+i2c0: i2c@113100 {
+	compatible = "netlogic,xlp980-i2c";
+	#address-cells = <1>;
+	#size-cells = <0>;
+	reg = <0 0x113100 0x100>;
+	clock-frequency = <400000>;
+	interrupts = <30>;
+	interrupt-parent = <&pic>;
+};
diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt
@@ -125,6 +125,7 @@ mxicy	Macronix International Co., Ltd.
 national	National Semiconductor
 neonode		Neonode Inc.
 netgear	NETGEAR
+netlogic	Broadcom Corporation (formerly NetLogic Microsystems)
 newhaven	Newhaven Display International
 nintendo	Nintendo
 nokia	Nokia

diff --git a/Documentation/i2c/slave-eeprom-backend b/Documentation/i2c/slave-eeprom-backend
@@ -0,0 +1,14 @@
+Linux I2C slave eeprom backend
+==============================
+
+by Wolfram Sang <[email protected]> in 2014-15
+
+This is a proof-of-concept backend which acts like an EEPROM on the connected
+I2C bus. The memory contents can be modified from userspace via this file
+located in sysfs:
+
+	/sys/bus/i2c/devices/<device-direcory>/slave-eeprom
+
+As of 2015, Linux doesn't support poll on binary sysfs files, so there is no
+notfication when another master changed the content.
+
diff --git a/Documentation/i2c/slave-interface b/Documentation/i2c/slave-interface
@@ -0,0 +1,179 @@
+Linux I2C slave interface description
+=====================================
+
+by Wolfram Sang <[email protected]> in 2014-15
+
+Linux can also be an I2C slave in case I2C controllers have slave support.
+Besides this HW requirement, one also needs a software backend providing the
+actual functionality. An example for this is the slave-eeprom driver, which
+acts as a dual memory driver. While another I2C master on the bus can access it
+like a regular EEPROM, the Linux I2C slave can access the content via sysfs and
+retrieve/provide information as needed. The software backend driver and the I2C
+bus driver communicate via events. Here is a small graph visualizing the data
+flow and the means by which data is transported. The dotted line marks only one
+example. The backend could also use e.g. a character device, be in-kernel
+only, or something completely different:
+
+
+              e.g. sysfs        I2C slave events        I/O registers
+  +-----------+   v    +---------+     v     +--------+  v  +------------+
+  | Userspace +........+ Backend +-----------+ Driver +-----+ Controller |
+  +-----------+        +---------+           +--------+     +------------+
+                                                                | |
+  ----------------------------------------------------------------+--  I2C
+  --------------------------------------------------------------+----  Bus
+
+Note: Technically, there is also the I2C core between the backend and the
+driver. However, at this time of writing, the layer is transparent.
+
+
+User manual
+===========
+
+I2C slave backends behave like standard I2C clients. So, you can instantiate
+them like described in the document 'instantiating-devices'. A quick example
+for instantiating the slave-eeprom driver from userspace:
+
+  # echo 0-0064 > /sys/bus/i2c/drivers/i2c-slave-eeprom/bind
+
+Each backend should come with separate documentation to describe its specific
+behaviour and setup.
+
+
+Developer manual
+================
+
+I2C slave events
+----------------
+
+The bus driver sends an event to the backend using the following function:
+
+	ret = i2c_slave_event(client, event, &val)
+
+'client' describes the i2c slave device. 'event' is one of the special event
+types described hereafter. 'val' holds an u8 value for the data byte to be
+read/written and is thus bidirectional. The pointer to val must always be
+provided even if val is not used for an event, i.e. don't use NULL here. 'ret'
+is the return value from the backend. Mandatory events must be provided by the
+bus drivers and must be checked for by backend drivers.
+
+Event types:
+
+* I2C_SLAVE_WRITE_REQUESTED (mandatory)
+
+'val': unused
+'ret': always 0
+
+Another I2C master wants to write data to us. This event should be sent once
+our own address and the write bit was detected. The data did not arrive yet, so
+there is nothing to process or return. Wakeup or initialization probably needs
+to be done, though.
+
+* I2C_SLAVE_READ_REQUESTED (mandatory)
+
+'val': backend returns first byte to be sent
+'ret': always 0
+
+Another I2C master wants to read data from us. This event should be sent once
+our own address and the read bit was detected. After returning, the bus driver
+should transmit the first byte.
+
+* I2C_SLAVE_WRITE_RECEIVED (mandatory)
+
+'val': bus driver delivers received byte
+'ret': 0 if the byte should be acked, some errno if the byte should be nacked
+
+Another I2C master has sent a byte to us which needs to be set in 'val'. If 'ret'
+is zero, the bus driver should ack this byte. If 'ret' is an errno, then the byte
+should be nacked.
+
+* I2C_SLAVE_READ_PROCESSED (mandatory)
+
+'val': backend returns next byte to be sent
+'ret': always 0
+
+The bus driver requests the next byte to be sent to another I2C master in
+'val'. Important: This does not mean that the previous byte has been acked, it
+only means that the previous byte is shifted out to the bus! To ensure seamless
+transmission, most hardware requests the next byte when the previous one is
+still shifted out. If the master sends NACK and stops reading after the byte
+currently shifted out, this byte requested here is never used. It very likely
+needs to be sent again on the next I2C_SLAVE_READ_REQUEST, depending a bit on
+your backend, though.
+
+* I2C_SLAVE_STOP (mandatory)
+
+'val': unused
+'ret': always 0
+
+A stop condition was received. This can happen anytime and the backend should
+reset its state machine for I2C transfers to be able to receive new requests.
+
+
+Software backends
+-----------------
+
+If you want to write a software backend:
+
+* use a standard i2c_driver and its matching mechanisms
+* write the slave_callback which handles the above slave events
+  (best using a state machine)
+* register this callback via i2c_slave_register()
+
+Check the i2c-slave-eeprom driver as an example.
+
+
+Bus driver support
+------------------
+
+If you want to add slave support to the bus driver:
+
+* implement calls to register/unregister the slave and add those to the
+  struct i2c_algorithm. When registering, you probably need to set the i2c
+  slave address and enable slave specific interrupts. If you use runtime pm, you
+  should use pm_runtime_forbid() because your device usually needs to be powered
+  on always to be able to detect its slave address. When unregistering, do the
+  inverse of the above.
+
+* Catch the slave interrupts and send appropriate i2c_slave_events to the backend.
+
+Check the i2c-rcar driver as an example.
+
+
+About ACK/NACK
+--------------
+
+It is good behaviour to always ACK the address phase, so the master knows if a
+device is basically present or if it mysteriously disappeared. Using NACK to
+state being busy is troublesome. SMBus demands to always ACK the address phase,
+while the I2C specification is more loose on that. Most I2C controllers also
+automatically ACK when detecting their slave addresses, so there is no option
+to NACK them. For those reasons, this API does not support NACK in the address
+phase.
+
+Currently, there is no slave event to report if the master did ACK or NACK a
+byte when it reads from us. We could make this an optional event if the need
+arises. However, cases should be extremely rare because the master is expected
+to send STOP after that and we have an event for that. Also, keep in mind not
+all I2C controllers have the possibility to report that event.
+
+
+About buffers
+-------------
+
+During development of this API, the question of using buffers instead of just
+bytes came up. Such an extension might be possible, usefulness is unclear at
+this time of writing. Some points to keep in mind when using buffers:
+
+* Buffers should be opt-in and slave drivers will always have to support
+  byte-based transactions as the ultimate fallback because this is how the
+  majority of HW works.
+
+* For backends simulating hardware registers, buffers are not helpful because
+  on writes an action should be immediately triggered. For reads, the data in
+  the buffer might get stale.
+
+* A master can send STOP at any time. For partially transferred buffers, this
+  means additional code to handle this exception. Such code tends to be
+  error-prone.
+
diff --git a/Documentation/i2c/summary b/Documentation/i2c/summary
@@ -41,7 +41,3 @@ integrated than Algorithm and Adapter.
 
 For a given configuration, you will need a driver for your I2C bus, and
 drivers for your I2C devices (usually one driver for each device).
-
-At this time, Linux only operates I2C (or SMBus) in master mode; you can't
-use these APIs to make a Linux system behave as a slave/device, either to
-speak a custom protocol or to emulate some other device.
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
@@ -485,6 +485,15 @@ config I2C_DESIGNWARE_BAYTRAIL
 	  the platform firmware controlling it. You should say Y if running on
 	  a BayTrail system using the AXP288.
 
+config I2C_DIGICOLOR
+	tristate "Conexant Digicolor I2C driver"
+	depends on ARCH_DIGICOLOR
+	help
+	  Support for Conexant Digicolor SoCs (CX92755) I2C controller driver.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-digicolor.
+
 config I2C_EFM32
 	tristate "EFM32 I2C controller"
 	depends on ARCH_EFM32 || COMPILE_TEST
@@ -574,6 +583,15 @@ config I2C_IOP3XX
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-iop3xx.
 
+config I2C_JZ4780
+	tristate "JZ4780 I2C controller interface support"
+	depends on MACH_JZ4780 || COMPILE_TEST
+	help
+	 If you say yes to this option, support will be included for the
+	 Ingenic JZ4780 I2C controller.
+
+	 If you don't know what to do here, say N.
+
 config I2C_KEMPLD
 	tristate "Kontron COM I2C Controller"
 	depends on MFD_KEMPLD
@@ -898,6 +916,16 @@ config I2C_XLR
 	  This driver can also be built as a module.  If so, the module
 	  will be called i2c-xlr.
 
+config I2C_XLP9XX
+	tristate "XLP9XX I2C support"
+	depends on CPU_XLP || COMPILE_TEST
+	help
+	  This driver enables support for the on-chip I2C interface of
+	  the Broadcom XLP9xx/XLP5xx MIPS processors.
+
+	  This driver can also be built as a module.  If so, the module will
+	  be called i2c-xlp9xx.
+
 config I2C_RCAR
 	tristate "Renesas R-Car I2C Controller"
 	depends on ARCH_SHMOBILE || COMPILE_TEST

diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
@@ -45,6 +45,7 @@ i2c-designware-platform-objs := i2c-designware-platdrv.o
 i2c-designware-platform-$(CONFIG_I2C_DESIGNWARE_BAYTRAIL) += i2c-designware-baytrail.o
 obj-$(CONFIG_I2C_DESIGNWARE_PCI)	+= i2c-designware-pci.o
 i2c-designware-pci-objs := i2c-designware-pcidrv.o
+obj-$(CONFIG_I2C_DIGICOLOR)	+= i2c-digicolor.o
 obj-$(CONFIG_I2C_EFM32)		+= i2c-efm32.o
 obj-$(CONFIG_I2C_EG20T)		+= i2c-eg20t.o
 obj-$(CONFIG_I2C_EXYNOS5)	+= i2c-exynos5.o
@@ -55,6 +56,7 @@ obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o
 obj-$(CONFIG_I2C_IMG)		+= i2c-img-scb.o
 obj-$(CONFIG_I2C_IMX)		+= i2c-imx.o
 obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o
+obj-$(CONFIG_I2C_JZ4780)	+= i2c-jz4780.o
 obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o
 obj-$(CONFIG_I2C_MESON)		+= i2c-meson.o
 obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o
@@ -87,6 +89,7 @@ obj-$(CONFIG_I2C_WMT)		+= i2c-wmt.o
 obj-$(CONFIG_I2C_OCTEON)	+= i2c-octeon.o
 obj-$(CONFIG_I2C_XILINX)	+= i2c-xiic.o
 obj-$(CONFIG_I2C_XLR)		+= i2c-xlr.o
+obj-$(CONFIG_I2C_XLP9XX)	+= i2c-xlp9xx.o
 obj-$(CONFIG_I2C_RCAR)		+= i2c-rcar.o
 
 # External I2C/SMBus adapter drivers