PATCHv6 1/2] dt-bindings: i2c: Add Altera I2C Controller

From: Thor Thayer <[email protected]>

Add the documentation to support the Altera synthesizable logic I2C Controller in FPGA.

---
v2 Change the subject to identify dt-bindings
Add synthesizable logic to description.
Change compatible string to "altr,softip-i2c" Make description of clock phandle singular since 1 clock. Remove altr, from fifo-size
Specify fifo-size is in bytes.
v3 Add version to compatible string "altr,softip-i2c-v1.0"
Add for use in FPGA in description.
v4 No Change - Add Acked-by
v5-6 No Change

---
 .../devicetree/bindings/i2c/i2c-altera.txt         | 39 ++++++++++++++++++++++
 1 file changed, 39 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-altera.txt

new file mode 100644
index 000000000000..767664f448ec
@@ -0,0 +1,39 @@
+* Altera I2C Controller
+* This is Altera's synthesizable logic block I2C Controller for use
+* in Altera's FPGAs.
+
+Required properties :
+ - compatible : should be "altr,softip-i2c-v1.0"
+ - reg        : Offset and length of the register set for the device
+ - interrupts : <IRQ> where IRQ is the interrupt number.
+ - clocks     : phandle to input clock.
+ - #address-cells = <1>;
+ - #size-cells = <0>;
+
+Recommended properties :
+ - clock-frequency : desired I2C bus clock frequency in Hz.
+
+Optional properties :
+ - fifo-size : Size of the RX and TX FIFOs in bytes.
+ - Child nodes conforming to i2c bus binding
+
+Example :
+
+	i2c@100080000 {
+		compatible = "altr,softip-i2c-v1.0";
+		reg = <0x00000001 0x00080000 0x00000040>;
+		interrupt-parent = <&intc>;
+		interrupts = <0 43 4>;
+		clocks = <&clk_0>;
+		clock-frequency = <100000>;
+		#address-cells = <1>;
+		#size-cells = <0>;
+		fifo-size = <4>;
+
+		eeprom@51 {
+			compatible = "atmel,24c32";
+			reg = <0x51>;
+			pagesize = <32>;
+		};
+	};
+

2.7.4

From: Thor Thayer <[email protected]>

Add driver support for the Altera I2C Controller. The I2C controller is soft IP for use in FPGAs.

---
v2 Remove altr, from fifo-size to agree with bindings.
Change compatible string to "altr,softip-i2c"

v3  Add version to compatible string "altr,softip-i2c-v1.0"
v4  Add default 100kHz message. Cleanup IRQ error message.
v5  Cleanup header usage - remove init.h.

Fix 1 byte RX bug and add convenience function for transfer shared by RX and TX. Use readl_poll_timeout_atomic() function.
Cache the I2C Interrupt Status Enable Register.
Cleanup of irq_mask by combining into 1 function.
Use i2c_8bit_addr_from_msg() for cleaner xfer_msg implementation. Restructure altr_i2c_xfer() without arrays and indexes.
Remove redundant assignments.
Remove function calls from inside if() statements.
Convert of_property_read_u32() to device_property_read_u32().
Call i2c_m_read() once in irq.
v6 Add isr_mask to structure kernel docs
Prepend altr_ to irq functions.
Remove recover function.
Remove i2c_m_rd(). Just code directly.
Use bool to signal completion.
Add isr_status to structure and structure kernel docs.
Change to threaded irq for core complete polling.
Add I2C_FUNC_SMBUS_EMUL to supported functionality.
Remove __func__ from dev_err() and dev_dbg().
Remove re-init on NACK.
Move MAINTAINERS addition from separate patch to here.
Add Reviewed-by: Andy Shevchenko from previous review.

---
 MAINTAINERS                     |   5 +
 drivers/i2c/busses/Kconfig      |  10 +
 drivers/i2c/busses/Makefile     |   1 +
 drivers/i2c/busses/i2c-altera.c | 511 ++++++++++++++++++++++++++++++++++++++++
 4 files changed, 527 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-altera.c

index d0ec5995abab..843de2821a43 100644
@@ -644,6 +644,11 @@ ALPS PS/2 TOUCHPAD DRIVER
 R:	Pali Rohár <[email protected]>
 F:	drivers/input/mouse/alps.*
 
+ALTERA I2C CONTROLLER DRIVER
+M:	Thor Thayer <[email protected]>
+S:	Maintained
+F:	drivers/i2c/busses/i2c-altera.c
+
 ALTERA MAILBOX DRIVER
 M:	Ley Foon Tan <[email protected]>
 L:	[email protected] (moderated for non-subscribers)

index edc0cfb6fc1a..47165d7d486e 100644
@@ -336,6 +336,16 @@ config I2C_POWERMAC
 
 comment "I2C system bus drivers (mostly embedded / system-on-chip)"
 
+config I2C_ALTERA
+	tristate "Altera Soft IP I2C"
+	depends on (ARCH_SOCFPGA || NIOS2) && OF
+	help
+	  If you say yes to this option, support will be included for the
+	  Altera Soft IP I2C interfaces on SoCFPGA and Nios2 architectures.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called i2c-altera.
+
 config I2C_ASPEED
 	tristate "Aspeed I2C Controller"
 	depends on ARCH_ASPEED || COMPILE_TEST

index 562daf738048..a57812fd2179 100644
@@ -30,6 +30,7 @@ obj-$(CONFIG_I2C_HYDRA)		+= i2c-hydra.o
 obj-$(CONFIG_I2C_POWERMAC)	+= i2c-powermac.o
 
 # Embedded system I2C/SMBus host controller drivers
+obj-$(CONFIG_I2C_ALTERA)	+= i2c-altera.o
 obj-$(CONFIG_I2C_ASPEED)	+= i2c-aspeed.o
 obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o
 obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o

2.7.4

Applied to for-next (will be in v4.14), thanks!

Yes, based on your previous feedback, I changed to a threaded IRQ as shown below. The altr_i2c_isr_quick wakes up this IRQ handler if the status is non-zero.

+
+ ret = devm_request_threaded_irq(&pdev->dev, irq, altr_i2c_isr_quick,
+ altr_i2c_isr, IRQF_ONESHOT,
+ pdev->name, idev);

Thanks for the review and applying the patch!

And please use [PATCH V6 RESEND ...] in the future; the double '[[' confuses the tools like patchwork.

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Applied to for-next (will be in v4.14), thanks!

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