path: root/Documentation
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authorLinus Torvalds <torvalds@linux-foundation.org>2013-04-29 09:40:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2013-04-29 09:40:35 -0700
commit000a74f41e601bc4e36a760aa42f219a019c5391 (patch)
tree6ff200c5112af40ef97afacac07f862aa428edb9 /Documentation
parent8127b39e700f965a60fca443d23f3e171bf7c3a9 (diff)
parent42fed7ba44e4e8c1fb27b28ad14490cb1daff3c7 (diff)
Merge tag 'pinctrl-for-v3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl
Pull pinctrl update from Linus Walleij: "These are the pinctrl changes for v3.10: - Patrice Chotard contributed a new configuration debugfs interface and reintroduced fine-grained locking into the core: instead of having a "big pinctrl lock" we have a per-controller lock and specialized locks for the global controller and pinctrl handle lists. - Haoijan Zhuang deleted all the PXA and MMP2 pinctrl drivers and replaced them with pinctrl-single (which is also used by other SoCs) so we are gaining consolidation. The platform particulars now come in through the device tree. - Haoijan also added support for generic pin config into the pinctrl-single driver which is another big consolidation win. - Finally also GPIO ranges are now supported by the pinctrl-single driver. - Tomasz Figa contributed a new Samsung S3C pinctrl driver, bringing more of the older Samsung platforms under the pinctrl umbrella and out of arch/arm. - Maxime Ripard contributed new Allwinner A10/A13 drivers. - Sachin Kamat, Wei Yongjun and Axel Lin did a lot of cleanups." * tag 'pinctrl-for-v3.10' of git://git.kernel.org/pub/scm/linux/kernel/git/linusw/linux-pinctrl: (66 commits) pinctrl: move subsystem mutex to pinctrl_dev struct pinctrl/pinconfig: fix misplaced goto pinctrl: s3c64xx: Fix build error caused by undefined chained_irq_enter pinctrl/pinconfig: add debug interface pinctrl: abx500: fix issue when no pdata pinctrl: pinctrl-single: add missing double quote pinctrl: sunxi: Rename wemac functions to emac pinctrl: exynos5440: add gpio interrupt support pinctrl: exynos5440: fix probe failure due to missing pin-list in config nodes pinctrl: ab8505: Staticize some symbols pinctrl: ab8540: Staticize some symbols pinctrl: ab9540: Staticize some symbols pinctrl: ab8500: Staticize some symbols pinctrl: abx500: Staticize some symbols pinctrl: Add pinctrl-s3c64xx driver pinctrl: samsung: Handle banks with two configuration registers pinctrl: samsung: Remove hardcoded register offsets pinctrl: samsung: Split pin bank description into two structures pinctrl: samsung: Include pinctrl-exynos driver data conditionally pinctrl: samsung: Protect bank registers with a spinlock ...
Diffstat (limited to 'Documentation')
4 files changed, 225 insertions, 5 deletions
diff --git a/Documentation/devicetree/bindings/gpio/gpio.txt b/Documentation/devicetree/bindings/gpio/gpio.txt
index a33628759d3..d933af37069 100644
--- a/Documentation/devicetree/bindings/gpio/gpio.txt
+++ b/Documentation/devicetree/bindings/gpio/gpio.txt
@@ -98,7 +98,7 @@ announce the pinrange to the pin ctrl subsystem. For example,
compatible = "fsl,qe-pario-bank-e", "fsl,qe-pario-bank";
reg = <0x1460 0x18>;
- gpio-ranges = <&pinctrl1 20 10>, <&pinctrl2 50 20>;
+ gpio-ranges = <&pinctrl1 0 20 10>, <&pinctrl2 10 50 20>;
@@ -107,8 +107,8 @@ where,
Next values specify the base pin and number of pins for the range
handled by 'qe_pio_e' gpio. In the given example from base pin 20 to
- pin 29 under pinctrl1 and pin 50 to pin 69 under pinctrl2 is handled
- by this gpio controller.
+ pin 29 under pinctrl1 with gpio offset 0 and pin 50 to pin 69 under
+ pinctrl2 with gpio offset 10 is handled by this gpio controller.
The pinctrl node must have "#gpio-range-cells" property to show number of
arguments to pass with phandle from gpio controllers node.
diff --git a/Documentation/devicetree/bindings/pinctrl/pinctrl-single.txt b/Documentation/devicetree/bindings/pinctrl/pinctrl-single.txt
index 2c81e45f137..08f0c3d0157 100644
--- a/Documentation/devicetree/bindings/pinctrl/pinctrl-single.txt
+++ b/Documentation/devicetree/bindings/pinctrl/pinctrl-single.txt
@@ -1,7 +1,9 @@
One-register-per-pin type device tree based pinctrl driver
Required properties:
-- compatible : "pinctrl-single"
+- compatible : "pinctrl-single" or "pinconf-single".
+ "pinctrl-single" means that pinconf isn't supported.
+ "pinconf-single" means that generic pinconf is supported.
- reg : offset and length of the register set for the mux registers
@@ -14,9 +16,61 @@ Optional properties:
- pinctrl-single,function-off : function off mode for disabled state if
available and same for all registers; if not specified, disabling of
pin functions is ignored
- pinctrl-single,bit-per-mux : boolean to indicate that one register controls
more than one pin
+- pinctrl-single,drive-strength : array of value that are used to configure
+ drive strength in the pinmux register. They're value of drive strength
+ current and drive strength mask.
+ /* drive strength current, mask */
+ pinctrl-single,power-source = <0x30 0xf0>;
+- pinctrl-single,bias-pullup : array of value that are used to configure the
+ input bias pullup in the pinmux register.
+ /* input, enabled pullup bits, disabled pullup bits, mask */
+ pinctrl-single,bias-pullup = <0 1 0 1>;
+- pinctrl-single,bias-pulldown : array of value that are used to configure the
+ input bias pulldown in the pinmux register.
+ /* input, enabled pulldown bits, disabled pulldown bits, mask */
+ pinctrl-single,bias-pulldown = <2 2 0 2>;
+ * Two bits to control input bias pullup and pulldown: User should use
+ pinctrl-single,bias-pullup & pinctrl-single,bias-pulldown. One bit means
+ pullup, and the other one bit means pulldown.
+ * Three bits to control input bias enable, pullup and pulldown. User should
+ use pinctrl-single,bias-pullup & pinctrl-single,bias-pulldown. Input bias
+ enable bit should be included in pullup or pulldown bits.
+ * Although driver could set PIN_CONFIG_BIAS_DISABLE, there's no property as
+ pinctrl-single,bias-disable. Because pinctrl single driver could implement
+ it by calling pulldown, pullup disabled.
+- pinctrl-single,input-schmitt : array of value that are used to configure
+ input schmitt in the pinmux register. In some silicons, there're two input
+ schmitt value (rising-edge & falling-edge) in the pinmux register.
+ /* input schmitt value, mask */
+ pinctrl-single,input-schmitt = <0x30 0x70>;
+- pinctrl-single,input-schmitt-enable : array of value that are used to
+ configure input schmitt enable or disable in the pinmux register.
+ /* input, enable bits, disable bits, mask */
+ pinctrl-single,input-schmitt-enable = <0x30 0x40 0 0x70>;
+- pinctrl-single,gpio-range : list of value that are used to configure a GPIO
+ range. They're value of subnode phandle, pin base in pinctrl device, pin
+ number in this range, GPIO function value of this GPIO range.
+ The number of parameters is depend on #pinctrl-single,gpio-range-cells
+ property.
+ /* pin base, nr pins & gpio function */
+ pinctrl-single,gpio-range = <&range 0 3 0 &range 3 9 1>;
This driver assumes that there is only one register for each pin (unless the
pinctrl-single,bit-per-mux is set), and uses the common pinctrl bindings as
specified in the pinctrl-bindings.txt document in this directory.
@@ -42,6 +96,20 @@ Where 0xdc is the offset from the pinctrl register base address for the
device pinctrl register, 0x18 is the desired value, and 0xff is the sub mask to
be used when applying this change to the register.
+Optional sub-node: In case some pins could be configured as GPIO in the pinmux
+register, those pins could be defined as a GPIO range. This sub-node is required
+by pinctrl-single,gpio-range property.
+Required properties in sub-node:
+- #pinctrl-single,gpio-range-cells : the number of parameters after phandle in
+ pinctrl-single,gpio-range property.
+ range: gpio-range {
+ #pinctrl-single,gpio-range-cells = <3>;
+ };
/* SoC common file */
@@ -58,7 +126,7 @@ pmx_core: pinmux@4a100040 {
/* second controller instance for pins in wkup domain */
pmx_wkup: pinmux@4a31e040 {
- compatible = "pinctrl-single;
+ compatible = "pinctrl-single";
reg = <0x4a31e040 0x0038>;
#address-cells = <1>;
#size-cells = <0>;
@@ -76,6 +144,29 @@ control_devconf0: pinmux@48002274 {
pinctrl-single,function-mask = <0x5F>;
+/* third controller instance for pins in gpio domain */
+pmx_gpio: pinmux@d401e000 {
+ compatible = "pinconf-single";
+ reg = <0xd401e000 0x0330>;
+ #address-cells = <1>;
+ #size-cells = <1>;
+ ranges;
+ pinctrl-single,register-width = <32>;
+ pinctrl-single,function-mask = <7>;
+ /* sparse GPIO range could be supported */
+ pinctrl-single,gpio-range = <&range 0 3 0 &range 3 9 1
+ &range 12 1 0 &range 13 29 1
+ &range 43 1 0 &range 44 49 1
+ &range 94 1 1 &range 96 2 1>;
+ range: gpio-range {
+ #pinctrl-single,gpio-range-cells = <3>;
+ };
/* board specific .dts file */
&pmx_core {
@@ -96,6 +187,15 @@ control_devconf0: pinmux@48002274 {
+ uart0_pins: pinmux_uart0_pins {
+ pinctrl-single,pins = <
+ 0x208 0 /* UART0_RXD (IOCFG138) */
+ 0x20c 0 /* UART0_TXD (IOCFG139) */
+ >;
+ pinctrl-single,bias-pulldown = <0 2 2>;
+ pinctrl-single,bias-pullup = <0 1 1>;
+ };
/* map uart2 pins */
uart2_pins: pinmux_uart2_pins {
pinctrl-single,pins = <
@@ -122,6 +222,11 @@ control_devconf0: pinmux@48002274 {
+&uart1 {
+ pinctrl-names = "default";
+ pinctrl-0 = <&uart0_pins>;
&uart2 {
pinctrl-names = "default";
pinctrl-0 = <&uart2_pins>;
diff --git a/Documentation/devicetree/bindings/pinctrl/samsung-pinctrl.txt b/Documentation/devicetree/bindings/pinctrl/samsung-pinctrl.txt
index 4598a47aa0c..c70fca146e9 100644
--- a/Documentation/devicetree/bindings/pinctrl/samsung-pinctrl.txt
+++ b/Documentation/devicetree/bindings/pinctrl/samsung-pinctrl.txt
@@ -7,6 +7,7 @@ on-chip controllers onto these pads.
Required Properties:
- compatible: should be one of the following.
+ - "samsung,s3c64xx-pinctrl": for S3C64xx-compatible pin-controller,
- "samsung,exynos4210-pinctrl": for Exynos4210 compatible pin-controller.
- "samsung,exynos4x12-pinctrl": for Exynos4x12 compatible pin-controller.
- "samsung,exynos5250-pinctrl": for Exynos5250 compatible pin-controller.
@@ -105,6 +106,8 @@ B. External Wakeup Interrupts: For supporting external wakeup interrupts, a
- compatible: identifies the type of the external wakeup interrupt controller
The possible values are:
+ - samsung,s3c64xx-wakeup-eint: represents wakeup interrupt controller
+ found on Samsung S3C64xx SoCs,
- samsung,exynos4210-wakeup-eint: represents wakeup interrupt controller
found on Samsung Exynos4210 SoC.
- interrupt-parent: phandle of the interrupt parent to which the external
diff --git a/Documentation/pinctrl.txt b/Documentation/pinctrl.txt
index a2b57e0a1db..447fd4cd54e 100644
--- a/Documentation/pinctrl.txt
+++ b/Documentation/pinctrl.txt
@@ -736,6 +736,13 @@ All the above functions are mandatory to implement for a pinmux driver.
Pin control interaction with the GPIO subsystem
+Note that the following implies that the use case is to use a certain pin
+from the Linux kernel using the API in <linux/gpio.h> with gpio_request()
+and similar functions. There are cases where you may be using something
+that your datasheet calls "GPIO mode" but actually is just an electrical
+configuration for a certain device. See the section below named
+"GPIO mode pitfalls" for more details on this scenario.
The public pinmux API contains two functions named pinctrl_request_gpio()
and pinctrl_free_gpio(). These two functions shall *ONLY* be called from
gpiolib-based drivers as part of their gpio_request() and
@@ -774,6 +781,111 @@ obtain the function "gpioN" where "N" is the global GPIO pin number if no
special GPIO-handler is registered.
+GPIO mode pitfalls
+Sometime the developer may be confused by a datasheet talking about a pin
+being possible to set into "GPIO mode". It appears that what hardware
+engineers mean with "GPIO mode" is not necessarily the use case that is
+implied in the kernel interface <linux/gpio.h>: a pin that you grab from
+kernel code and then either listen for input or drive high/low to
+assert/deassert some external line.
+Rather hardware engineers think that "GPIO mode" means that you can
+software-control a few electrical properties of the pin that you would
+not be able to control if the pin was in some other mode, such as muxed in
+for a device.
+Example: a pin is usually muxed in to be used as a UART TX line. But during
+system sleep, we need to put this pin into "GPIO mode" and ground it.
+If you make a 1-to-1 map to the GPIO subsystem for this pin, you may start
+to think that you need to come up with something real complex, that the
+pin shall be used for UART TX and GPIO at the same time, that you will grab
+a pin control handle and set it to a certain state to enable UART TX to be
+muxed in, then twist it over to GPIO mode and use gpio_direction_output()
+to drive it low during sleep, then mux it over to UART TX again when you
+wake up and maybe even gpio_request/gpio_free as part of this cycle. This
+all gets very complicated.
+The solution is to not think that what the datasheet calls "GPIO mode"
+has to be handled by the <linux/gpio.h> interface. Instead view this as
+a certain pin config setting. Look in e.g. <linux/pinctrl/pinconf-generic.h>
+and you find this in the documentation:
+ PIN_CONFIG_OUTPUT: this will configure the pin in output, use argument
+ 1 to indicate high level, argument 0 to indicate low level.
+So it is perfectly possible to push a pin into "GPIO mode" and drive the
+line low as part of the usual pin control map. So for example your UART
+driver may look like this:
+#include <linux/pinctrl/consumer.h>
+struct pinctrl *pinctrl;
+struct pinctrl_state *pins_default;
+struct pinctrl_state *pins_sleep;
+pins_default = pinctrl_lookup_state(uap->pinctrl, PINCTRL_STATE_DEFAULT);
+pins_sleep = pinctrl_lookup_state(uap->pinctrl, PINCTRL_STATE_SLEEP);
+/* Normal mode */
+retval = pinctrl_select_state(pinctrl, pins_default);
+/* Sleep mode */
+retval = pinctrl_select_state(pinctrl, pins_sleep);
+And your machine configuration may look like this:
+static unsigned long uart_default_mode[] = {
+static unsigned long uart_sleep_mode[] = {
+static struct pinctrl_map __initdata pinmap[] = {
+ "u0_group", "u0"),
+ "UART_TX_PIN", uart_default_mode),
+ PIN_MAP_MUX_GROUP("uart", PINCTRL_STATE_SLEEP, "pinctrl-foo",
+ "u0_group", "gpio-mode"),
+ "UART_TX_PIN", uart_sleep_mode),
+foo_init(void) {
+ pinctrl_register_mappings(pinmap, ARRAY_SIZE(pinmap));
+Here the pins we want to control are in the "u0_group" and there is some
+function called "u0" that can be enabled on this group of pins, and then
+everything is UART business as usual. But there is also some function
+named "gpio-mode" that can be mapped onto the same pins to move them into
+GPIO mode.
+This will give the desired effect without any bogus interaction with the
+GPIO subsystem. It is just an electrical configuration used by that device
+when going to sleep, it might imply that the pin is set into something the
+datasheet calls "GPIO mode" but that is not the point: it is still used
+by that UART device to control the pins that pertain to that very UART
+driver, putting them into modes needed by the UART. GPIO in the Linux
+kernel sense are just some 1-bit line, and is a different use case.
+How the registers are poked to attain the push/pull and output low
+configuration and the muxing of the "u0" or "gpio-mode" group onto these
+pins is a question for the driver.
+Some datasheets will be more helpful and refer to the "GPIO mode" as
+"low power mode" rather than anything to do with GPIO. This often means
+the same thing electrically speaking, but in this latter case the
+software engineers will usually quickly identify that this is some
+specific muxing/configuration rather than anything related to the GPIO
Board/machine configuration