[PATCH v6 2/8] pinctrl: imx27: imx27 pincontrol driver

On Mon, Oct 28, 2013 at 06:17:41AM -0500, Kumar Gala wrote:

On Oct 28, 2013, at 4:00 AM, Markus Pargmann wrote:

quoted

imx27 pincontrol driver using the imx1 core driver. The DT bindings are
similar to other imx pincontrol drivers.

Signed-off-by: Markus Pargmann <redacted>
Acked-by: Sascha Hauer <s.hauer@pengutronix.de>
Acked-by: Shawn Guo <redacted>
---
.../bindings/pinctrl/fsl,imx27-pinctrl.txt         |  89 ++++
drivers/pinctrl/Kconfig                            |   8 +
drivers/pinctrl/Makefile                           |   1 +
drivers/pinctrl/pinctrl-imx27.c                    | 477 +++++++++++++++++++++
4 files changed, 575 insertions(+)
create mode 100644 Documentation/devicetree/bindings/pinctrl/fsl,imx27-pinctrl.txt
create mode 100644 drivers/pinctrl/pinctrl-imx27.c

diff --git a/Documentation/devicetree/bindings/pinctrl/fsl,imx27-pinctrl.txt b/Documentation/devicetree/bindings/pinctrl/fsl,imx27-pinctrl.txt
new file mode 100644
index 0000000..32c81c8
--- /dev/null
+++ b/Documentation/devicetree/bindings/pinctrl/fsl,imx27-pinctrl.txt

@@ -0,0 +1,89 @@
+* Freescale IMX27 IOMUX Controller
+
+Required properties:
+- compatible: "fsl,imx27-iomuxc"
+
+The iomuxc driver node should define subnodes containing of pinctrl configuration subnodes.

Here would probably be a good point to reference "pinctrl/pinctrl-bindings.txt"

Okay.

quoted

+
+Required properties for pin configuration node:
+- fsl,pins: three integers array, represents a group of pins mux and config
+  setting. The format is fsl,pins = <PIN MUX_ID CONFIG>.
+
+  PIN is an integer between 0 and 0xbf. imx27 has 6 ports with 32 configurable
+  configurable pins each. PIN is PORT * 32 + PORT_PIN, PORT_PIN is the pin
+  number on the specific port (between 0 and 31).

I might be coming late to this, so feel free to ignore if this has already been discussed.

Why not encode PORT in fsl,pins so it would be <PORT PORT_PIN MUX_ID CONFIG> ?

The port is still visible in the pin id as each port has 32 pins = 0x20.
So the ports start at 0x00, 0x20, 0x40, 0x60, 0x80 and 0xa0. So I am not
sure if it is necessary to seperate PORT and PORT_PIN, I personally
prefer only one PIN_ID field.

quoted

+
+  MUX_ID is
+    function + (direction << 2) + (gpio_oconf << 4) + (gpio_iconfa << 8) + (gpio_iconfb << 10)
+
+    function:      0 - Primary function
+                   1 - Alternate function
+                   2 - GPIO
+      Registers GIUS (GPIO In Use) and GPR (General Purpose Register)
+
+    direction:     0 - Input
+                   1 - Output
+      Register DDIR
+
+    gpio_oconf:    0 - A_IN
+                   1 - B_IN
+                   2 - C_IN
+                   3 - Data Register

what does this mean?

These are additional output configurations for GPIO. 3 is normal GPIO,
0-2 are other pinfunctions that are mapped as output to this pin. It is
described in the i.MX27 reference manual in detail.

quoted

+      Registers OCR1 and OCR2
+
+    gpio_iconfa/b: 0 - GPIO_IN
+                   1 - Interrupt Status Register
+                   2 - 0
+                   3 - 1

What does any of these option mean (especially 2 & 3)?

This is the input configuration for a pin in GPIO mode. 0 will connect
it to GPIO input of the pad, 1 to the interrupt status register, 2 and 3
to constant low or high.

quoted

+      Registers ICONFA1, ICONFA2, ICONFB1 and ICONFB2
+
+

Someone should be able to reasonable read this and determine how to set MUX_ID w/o having to reference the HW manual.

I will add a little bit more documentation here. But in general the
corresponding reference manual chapters should be used to create a
correct MUX_ID. I don't think DT binding documentation is the right
place to describe the hardware.

quoted

+  CONFIG can be 0 or 1, meaning Pullup disable/enable.

just for clarity do:
    CONFIG: 0 - Pullup disabled
            1 - Pullup enabled

Okay, will change.

Thanks,

Markus Pargmann

quoted

+
+
+
+
+Example:
+
+iomuxc: iomuxc at 10015000 {
+	compatible = "fsl,imx27-iomuxc";
+	reg = <0x10015000 0x600>;
+
+	uart {
+		pinctrl_uart1: uart-1 {
+			fsl,pins = <
+				0x8c 0x004 0x0 /* UART1_TXD__UART1_TXD */
+				0x8d 0x000 0x0 /* UART1_RXD__UART1_RXD */
+				0x8e 0x004 0x0 /* UART1_CTS__UART1_CTS */
+				0x8f 0x000 0x0 /* UART1_RTS__UART1_RTS */
+			>;
+		};
+
+		...
+	};
+};
+
+
+For convenience there are macros defined in imx27-pinfunc.h which provide PIN
+and MUX_ID. They are structured as MX27_PAD_<Pad name>__<Signal name>. The names
+are defined in the i.MX27 reference manual.

quoted

+
+The above example using macros:
+
+iomuxc: iomuxc at 10015000 {
+	compatible = "fsl,imx27-iomuxc";
+	reg = <0x10015000 0x600>;
+
+	uart {
+		pinctrl_uart1: uart-1 {
+			fsl,pins = <
+				MX27_PAD_UART1_TXD__UART1_TXD 0x0
+				MX27_PAD_UART1_RXD__UART1_RXD 0x0
+				MX27_PAD_UART1_CTS__UART1_CTS 0x0
+				MX27_PAD_UART1_RTS__UART1_RTS 0x0
+			>;
+		};
+
+		...
+	};
+};

- k

-- 
Employee of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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