diff options
Diffstat (limited to 'Documentation')
25 files changed, 822 insertions, 58 deletions
diff --git a/Documentation/Changes b/Documentation/Changes index b175808..07c75d1 100644 --- a/Documentation/Changes +++ b/Documentation/Changes @@ -196,13 +196,6 @@ chmod 0644 /dev/cpu/microcode as root before you can use this. You'll probably also want to get the user-space microcode_ctl utility to use with this. -Powertweak ----------- - -If you are running v0.1.17 or earlier, you should upgrade to -version v0.99.0 or higher. Running old versions may cause problems -with programs using shared memory. - udev ---- udev is a userspace application for populating /dev dynamically with @@ -366,10 +359,6 @@ Intel P6 microcode ------------------ o <http://www.urbanmyth.org/microcode/> -Powertweak ----------- -o <http://powertweak.sourceforge.net/> - udev ---- o <http://www.kernel.org/pub/linux/utils/kernel/hotplug/udev.html> diff --git a/Documentation/DocBook/device-drivers.tmpl b/Documentation/DocBook/device-drivers.tmpl index 6c9d9d3..f517008 100644 --- a/Documentation/DocBook/device-drivers.tmpl +++ b/Documentation/DocBook/device-drivers.tmpl @@ -58,7 +58,7 @@ </sect1> <sect1><title>Wait queues and Wake events</title> !Iinclude/linux/wait.h -!Ekernel/wait.c +!Ekernel/sched/wait.c </sect1> <sect1><title>High-resolution timers</title> !Iinclude/linux/ktime.h diff --git a/Documentation/assoc_array.txt b/Documentation/assoc_array.txt index f4faec0..2f2c6cd 100644 --- a/Documentation/assoc_array.txt +++ b/Documentation/assoc_array.txt @@ -164,10 +164,10 @@ This points to a number of methods, all of which need to be provided: (4) Diff the index keys of two objects. - int (*diff_objects)(const void *a, const void *b); + int (*diff_objects)(const void *object, const void *index_key); - Return the bit position at which the index keys of two objects differ or - -1 if they are the same. + Return the bit position at which the index key of the specified object + differs from the given index key or -1 if they are the same. (5) Free an object. diff --git a/Documentation/devicetree/bindings/arm/omap/mpu.txt b/Documentation/devicetree/bindings/arm/omap/mpu.txt index 1a5a42c..83f405b 100644 --- a/Documentation/devicetree/bindings/arm/omap/mpu.txt +++ b/Documentation/devicetree/bindings/arm/omap/mpu.txt @@ -7,10 +7,18 @@ The MPU contain CPUs, GIC, L2 cache and a local PRCM. Required properties: - compatible : Should be "ti,omap3-mpu" for OMAP3 Should be "ti,omap4-mpu" for OMAP4 + Should be "ti,omap5-mpu" for OMAP5 - ti,hwmods: "mpu" Examples: +- For an OMAP5 SMP system: + +mpu { + compatible = "ti,omap5-mpu"; + ti,hwmods = "mpu" +}; + - For an OMAP4 SMP system: mpu { diff --git a/Documentation/devicetree/bindings/arm/pmu.txt b/Documentation/devicetree/bindings/arm/pmu.txt index 343781b..3e1e498 100644 --- a/Documentation/devicetree/bindings/arm/pmu.txt +++ b/Documentation/devicetree/bindings/arm/pmu.txt @@ -7,6 +7,7 @@ representation in the device tree should be done as under:- Required properties: - compatible : should be one of + "arm,armv8-pmuv3" "arm,cortex-a15-pmu" "arm,cortex-a9-pmu" "arm,cortex-a8-pmu" diff --git a/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt b/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt index 47ada1d..5d49f2b 100644 --- a/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt +++ b/Documentation/devicetree/bindings/arm/samsung/exynos-adc.txt @@ -49,7 +49,7 @@ adc@12D10000 { /* NTC thermistor is a hwmon device */ ncp15wb473@0 { compatible = "ntc,ncp15wb473"; - pullup-uV = <1800000>; + pullup-uv = <1800000>; pullup-ohm = <47000>; pulldown-ohm = <0>; io-channels = <&adc 4>; diff --git a/Documentation/devicetree/bindings/clock/exynos4-clock.txt b/Documentation/devicetree/bindings/clock/exynos4-clock.txt index c6bf8a6..a2ac2d9 100644 --- a/Documentation/devicetree/bindings/clock/exynos4-clock.txt +++ b/Documentation/devicetree/bindings/clock/exynos4-clock.txt @@ -6,7 +6,7 @@ SoC's in the Exynos4 family. Required Properties: -- comptible: should be one of the following. +- compatible: should be one of the following. - "samsung,exynos4210-clock" - controller compatible with Exynos4210 SoC. - "samsung,exynos4412-clock" - controller compatible with Exynos4412 SoC. diff --git a/Documentation/devicetree/bindings/clock/exynos5250-clock.txt b/Documentation/devicetree/bindings/clock/exynos5250-clock.txt index 24765c1..46f5c79 100644 --- a/Documentation/devicetree/bindings/clock/exynos5250-clock.txt +++ b/Documentation/devicetree/bindings/clock/exynos5250-clock.txt @@ -5,7 +5,7 @@ controllers within the Exynos5250 SoC. Required Properties: -- comptible: should be one of the following. +- compatible: should be one of the following. - "samsung,exynos5250-clock" - controller compatible with Exynos5250 SoC. - reg: physical base address of the controller and length of memory mapped diff --git a/Documentation/devicetree/bindings/clock/exynos5420-clock.txt b/Documentation/devicetree/bindings/clock/exynos5420-clock.txt index 32aa34e..458f347 100644 --- a/Documentation/devicetree/bindings/clock/exynos5420-clock.txt +++ b/Documentation/devicetree/bindings/clock/exynos5420-clock.txt @@ -5,7 +5,7 @@ controllers within the Exynos5420 SoC. Required Properties: -- comptible: should be one of the following. +- compatible: should be one of the following. - "samsung,exynos5420-clock" - controller compatible with Exynos5420 SoC. - reg: physical base address of the controller and length of memory mapped diff --git a/Documentation/devicetree/bindings/clock/exynos5440-clock.txt b/Documentation/devicetree/bindings/clock/exynos5440-clock.txt index 4499e99..9955dc9 100644 --- a/Documentation/devicetree/bindings/clock/exynos5440-clock.txt +++ b/Documentation/devicetree/bindings/clock/exynos5440-clock.txt @@ -5,7 +5,7 @@ controllers within the Exynos5440 SoC. Required Properties: -- comptible: should be "samsung,exynos5440-clock". +- compatible: should be "samsung,exynos5440-clock". - reg: physical base address of the controller and length of memory mapped region. diff --git a/Documentation/devicetree/bindings/gpio/8xxx_gpio.txt b/Documentation/devicetree/bindings/gpio/8xxx_gpio.txt index b0019eb..798cfc9 100644 --- a/Documentation/devicetree/bindings/gpio/8xxx_gpio.txt +++ b/Documentation/devicetree/bindings/gpio/8xxx_gpio.txt @@ -5,16 +5,42 @@ This is for the non-QE/CPM/GUTs GPIO controllers as found on Every GPIO controller node must have #gpio-cells property defined, this information will be used to translate gpio-specifiers. +See bindings/gpio/gpio.txt for details of how to specify GPIO +information for devices. + +The GPIO module usually is connected to the SoC's internal interrupt +controller, see bindings/interrupt-controller/interrupts.txt (the +interrupt client nodes section) for details how to specify this GPIO +module's interrupt. + +The GPIO module may serve as another interrupt controller (cascaded to +the SoC's internal interrupt controller). See the interrupt controller +nodes section in bindings/interrupt-controller/interrupts.txt for +details. Required properties: -- compatible : "fsl,<CHIP>-gpio" followed by "fsl,mpc8349-gpio" for - 83xx, "fsl,mpc8572-gpio" for 85xx and "fsl,mpc8610-gpio" for 86xx. -- #gpio-cells : Should be two. The first cell is the pin number and the - second cell is used to specify optional parameters (currently unused). - - interrupts : Interrupt mapping for GPIO IRQ. - - interrupt-parent : Phandle for the interrupt controller that - services interrupts for this device. -- gpio-controller : Marks the port as GPIO controller. +- compatible: "fsl,<chip>-gpio" followed by "fsl,mpc8349-gpio" + for 83xx, "fsl,mpc8572-gpio" for 85xx, or + "fsl,mpc8610-gpio" for 86xx. +- #gpio-cells: Should be two. The first cell is the pin number + and the second cell is used to specify optional + parameters (currently unused). +- interrupt-parent: Phandle for the interrupt controller that + services interrupts for this device. +- interrupts: Interrupt mapping for GPIO IRQ. +- gpio-controller: Marks the port as GPIO controller. + +Optional properties: +- interrupt-controller: Empty boolean property which marks the GPIO + module as an IRQ controller. +- #interrupt-cells: Should be two. Defines the number of integer + cells required to specify an interrupt within + this interrupt controller. The first cell + defines the pin number, the second cell + defines additional flags (trigger type, + trigger polarity). Note that the available + set of trigger conditions supported by the + GPIO module depends on the actual SoC. Example of gpio-controller nodes for a MPC8347 SoC: @@ -22,39 +48,27 @@ Example of gpio-controller nodes for a MPC8347 SoC: #gpio-cells = <2>; compatible = "fsl,mpc8347-gpio", "fsl,mpc8349-gpio"; reg = <0xc00 0x100>; - interrupts = <74 0x8>; interrupt-parent = <&ipic>; + interrupts = <74 0x8>; gpio-controller; + interrupt-controller; + #interrupt-cells = <2>; }; gpio2: gpio-controller@d00 { #gpio-cells = <2>; compatible = "fsl,mpc8347-gpio", "fsl,mpc8349-gpio"; reg = <0xd00 0x100>; - interrupts = <75 0x8>; interrupt-parent = <&ipic>; + interrupts = <75 0x8>; gpio-controller; }; -See booting-without-of.txt for details of how to specify GPIO -information for devices. - -To use GPIO pins as interrupt sources for peripherals, specify the -GPIO controller as the interrupt parent and define GPIO number + -trigger mode using the interrupts property, which is defined like -this: - -interrupts = <number trigger>, where: - - number: GPIO pin (0..31) - - trigger: trigger mode: - 2 = trigger on falling edge - 3 = trigger on both edges - -Example of device using this is: +Example of a peripheral using the GPIO module as an IRQ controller: funkyfpga@0 { compatible = "funky-fpga"; ... - interrupts = <4 3>; interrupt-parent = <&gpio1>; + interrupts = <4 3>; }; diff --git a/Documentation/devicetree/bindings/i2c/i2c-omap.txt b/Documentation/devicetree/bindings/i2c/i2c-omap.txt index 56564aa..7e49839 100644 --- a/Documentation/devicetree/bindings/i2c/i2c-omap.txt +++ b/Documentation/devicetree/bindings/i2c/i2c-omap.txt @@ -1,7 +1,8 @@ I2C for OMAP platforms Required properties : -- compatible : Must be "ti,omap3-i2c" or "ti,omap4-i2c" +- compatible : Must be "ti,omap2420-i2c", "ti,omap2430-i2c", "ti,omap3-i2c" + or "ti,omap4-i2c" - ti,hwmods : Must be "i2c<n>", n being the instance number (1-based) - #address-cells = <1>; - #size-cells = <0>; diff --git a/Documentation/devicetree/bindings/mmc/ti-omap.txt b/Documentation/devicetree/bindings/mmc/ti-omap.txt new file mode 100644 index 0000000..8de5799 --- /dev/null +++ b/Documentation/devicetree/bindings/mmc/ti-omap.txt @@ -0,0 +1,54 @@ +* TI MMC host controller for OMAP1 and 2420 + +The MMC Host Controller on TI OMAP1 and 2420 family provides +an interface for MMC, SD, and SDIO types of memory cards. + +This file documents differences between the core properties described +by mmc.txt and the properties used by the omap mmc driver. + +Note that this driver will not work with omap2430 or later omaps, +please see the omap hsmmc driver for the current omaps. + +Required properties: +- compatible: Must be "ti,omap2420-mmc", for OMAP2420 controllers +- ti,hwmods: For 2420, must be "msdi<n>", where n is controller + instance starting 1 + +Examples: + + msdi1: mmc@4809c000 { + compatible = "ti,omap2420-mmc"; + ti,hwmods = "msdi1"; + reg = <0x4809c000 0x80>; + interrupts = <83>; + dmas = <&sdma 61 &sdma 62>; + dma-names = "tx", "rx"; + }; + +* TI MMC host controller for OMAP1 and 2420 + +The MMC Host Controller on TI OMAP1 and 2420 family provides +an interface for MMC, SD, and SDIO types of memory cards. + +This file documents differences between the core properties described +by mmc.txt and the properties used by the omap mmc driver. + +Note that this driver will not work with omap2430 or later omaps, +please see the omap hsmmc driver for the current omaps. + +Required properties: +- compatible: Must be "ti,omap2420-mmc", for OMAP2420 controllers +- ti,hwmods: For 2420, must be "msdi<n>", where n is controller + instance starting 1 + +Examples: + + msdi1: mmc@4809c000 { + compatible = "ti,omap2420-mmc"; + ti,hwmods = "msdi1"; + reg = <0x4809c000 0x80>; + interrupts = <83>; + dmas = <&sdma 61 &sdma 62>; + dma-names = "tx", "rx"; + }; + diff --git a/Documentation/devicetree/bindings/net/fsl-fec.txt b/Documentation/devicetree/bindings/net/fsl-fec.txt index d536392..845ff84 100644 --- a/Documentation/devicetree/bindings/net/fsl-fec.txt +++ b/Documentation/devicetree/bindings/net/fsl-fec.txt @@ -15,6 +15,7 @@ Optional properties: only if property "phy-reset-gpios" is available. Missing the property will have the duration be 1 millisecond. Numbers greater than 1000 are invalid and 1 millisecond will be used instead. +- phy-supply: regulator that powers the Ethernet PHY. Example: @@ -25,4 +26,5 @@ ethernet@83fec000 { phy-mode = "mii"; phy-reset-gpios = <&gpio2 14 0>; /* GPIO2_14 */ local-mac-address = [00 04 9F 01 1B B9]; + phy-supply = <®_fec_supply>; }; diff --git a/Documentation/devicetree/bindings/rng/qcom,prng.txt b/Documentation/devicetree/bindings/rng/qcom,prng.txt new file mode 100644 index 0000000..8e5853c --- /dev/null +++ b/Documentation/devicetree/bindings/rng/qcom,prng.txt @@ -0,0 +1,17 @@ +Qualcomm MSM pseudo random number generator. + +Required properties: + +- compatible : should be "qcom,prng" +- reg : specifies base physical address and size of the registers map +- clocks : phandle to clock-controller plus clock-specifier pair +- clock-names : "core" clocks all registers, FIFO and circuits in PRNG IP block + +Example: + + rng@f9bff000 { + compatible = "qcom,prng"; + reg = <0xf9bff000 0x200>; + clocks = <&clock GCC_PRNG_AHB_CLK>; + clock-names = "core"; + }; diff --git a/Documentation/devicetree/bindings/spi/nvidia,tegra20-spi.txt b/Documentation/devicetree/bindings/spi/nvidia,tegra20-spi.txt deleted file mode 100644 index 6b9e518..0000000 --- a/Documentation/devicetree/bindings/spi/nvidia,tegra20-spi.txt +++ /dev/null @@ -1,5 +0,0 @@ -NVIDIA Tegra 2 SPI device - -Required properties: -- compatible : should be "nvidia,tegra20-spi". -- gpios : should specify GPIOs used for chipselect. diff --git a/Documentation/devicetree/bindings/vendor-prefixes.txt b/Documentation/devicetree/bindings/vendor-prefixes.txt index ce95ed1..edbb8d8 100644 --- a/Documentation/devicetree/bindings/vendor-prefixes.txt +++ b/Documentation/devicetree/bindings/vendor-prefixes.txt @@ -32,12 +32,14 @@ est ESTeem Wireless Modems fsl Freescale Semiconductor GEFanuc GE Fanuc Intelligent Platforms Embedded Systems, Inc. gef GE Fanuc Intelligent Platforms Embedded Systems, Inc. +gmt Global Mixed-mode Technology, Inc. hisilicon Hisilicon Limited. hp Hewlett Packard ibm International Business Machines (IBM) idt Integrated Device Technologies, Inc. img Imagination Technologies Ltd. intercontrol Inter Control Group +lg LG Corporation linux Linux-specific binding lsi LSI Corp. (LSI Logic) marvell Marvell Technology Group Ltd. diff --git a/Documentation/gpio/00-INDEX b/Documentation/gpio/00-INDEX new file mode 100644 index 0000000..1de43ae --- /dev/null +++ b/Documentation/gpio/00-INDEX @@ -0,0 +1,14 @@ +00-INDEX + - This file +gpio.txt + - Introduction to GPIOs and their kernel interfaces +consumer.txt + - How to obtain and use GPIOs in a driver +driver.txt + - How to write a GPIO driver +board.txt + - How to assign GPIOs to a consumer device and a function +sysfs.txt + - Information about the GPIO sysfs interface +gpio-legacy.txt + - Historical documentation of the deprecated GPIO integer interface diff --git a/Documentation/gpio/board.txt b/Documentation/gpio/board.txt new file mode 100644 index 0000000..0d03506 --- /dev/null +++ b/Documentation/gpio/board.txt @@ -0,0 +1,115 @@ +GPIO Mappings +============= + +This document explains how GPIOs can be assigned to given devices and functions. +Note that it only applies to the new descriptor-based interface. For a +description of the deprecated integer-based GPIO interface please refer to +gpio-legacy.txt (actually, there is no real mapping possible with the old +interface; you just fetch an integer from somewhere and request the +corresponding GPIO. + +Platforms that make use of GPIOs must select ARCH_REQUIRE_GPIOLIB (if GPIO usage +is mandatory) or ARCH_WANT_OPTIONAL_GPIOLIB (if GPIO support can be omitted) in +their Kconfig. Then, how GPIOs are mapped depends on what the platform uses to +describe its hardware layout. Currently, mappings can be defined through device +tree, ACPI, and platform data. + +Device Tree +----------- +GPIOs can easily be mapped to devices and functions in the device tree. The +exact way to do it depends on the GPIO controller providing the GPIOs, see the +device tree bindings for your controller. + +GPIOs mappings are defined in the consumer device's node, in a property named +<function>-gpios, where <function> is the function the driver will request +through gpiod_get(). For example: + + foo_device { + compatible = "acme,foo"; + ... + led-gpios = <&gpio 15 GPIO_ACTIVE_HIGH>, /* red */ + <&gpio 16 GPIO_ACTIVE_HIGH>, /* green */ + <&gpio 17 GPIO_ACTIVE_HIGH>; /* blue */ + + power-gpio = <&gpio 1 GPIO_ACTIVE_LOW>; + }; + +This property will make GPIOs 15, 16 and 17 available to the driver under the +"led" function, and GPIO 1 as the "power" GPIO: + + struct gpio_desc *red, *green, *blue, *power; + + red = gpiod_get_index(dev, "led", 0); + green = gpiod_get_index(dev, "led", 1); + blue = gpiod_get_index(dev, "led", 2); + + power = gpiod_get(dev, "power"); + +The led GPIOs will be active-high, while the power GPIO will be active-low (i.e. +gpiod_is_active_low(power) will be true). + +ACPI +---- +ACPI does not support function names for GPIOs. Therefore, only the "idx" +argument of gpiod_get_index() is useful to discriminate between GPIOs assigned +to a device. The "con_id" argument can still be set for debugging purposes (it +will appear under error messages as well as debug and sysfs nodes). + +Platform Data +------------- +Finally, GPIOs can be bound to devices and functions using platform data. Board +files that desire to do so need to include the following header: + + #include <linux/gpio/driver.h> + +GPIOs are mapped by the means of tables of lookups, containing instances of the +gpiod_lookup structure. Two macros are defined to help declaring such mappings: + + GPIO_LOOKUP(chip_label, chip_hwnum, dev_id, con_id, flags) + GPIO_LOOKUP_IDX(chip_label, chip_hwnum, dev_id, con_id, idx, flags) + +where + + - chip_label is the label of the gpiod_chip instance providing the GPIO + - chip_hwnum is the hardware number of the GPIO within the chip + - dev_id is the identifier of the device that will make use of this GPIO. If + NULL, the GPIO will be available to all devices. + - con_id is the name of the GPIO function from the device point of view. It + can be NULL. + - idx is the index of the GPIO within the function. + - flags is defined to specify the following properties: + * GPIOF_ACTIVE_LOW - to configure the GPIO as active-low + * GPIOF_OPEN_DRAIN - GPIO pin is open drain type. + * GPIOF_OPEN_SOURCE - GPIO pin is open source type. + +In the future, these flags might be extended to support more properties. + +Note that GPIO_LOOKUP() is just a shortcut to GPIO_LOOKUP_IDX() where idx = 0. + +A lookup table can then be defined as follows: + + struct gpiod_lookup gpios_table[] = { + GPIO_LOOKUP_IDX("gpio.0", 15, "foo.0", "led", 0, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP_IDX("gpio.0", 16, "foo.0", "led", 1, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP_IDX("gpio.0", 17, "foo.0", "led", 2, GPIO_ACTIVE_HIGH), + GPIO_LOOKUP("gpio.0", 1, "foo.0", "power", GPIO_ACTIVE_LOW), + }; + +And the table can be added by the board code as follows: + + gpiod_add_table(gpios_table, ARRAY_SIZE(gpios_table)); + +The driver controlling "foo.0" will then be able to obtain its GPIOs as follows: + + struct gpio_desc *red, *green, *blue, *power; + + red = gpiod_get_index(dev, "led", 0); + green = gpiod_get_index(dev, "led", 1); + blue = gpiod_get_index(dev, "led", 2); + + power = gpiod_get(dev, "power"); + gpiod_direction_output(power, 1); + +Since the "power" GPIO is mapped as active-low, its actual signal will be 0 +after this code. Contrary to the legacy integer GPIO interface, the active-low +property is handled during mapping and is thus transparent to GPIO consumers. diff --git a/Documentation/gpio/consumer.txt b/Documentation/gpio/consumer.txt new file mode 100644 index 0000000..07c74a3 --- /dev/null +++ b/Documentation/gpio/consumer.txt @@ -0,0 +1,197 @@ +GPIO Descriptor Consumer Interface +================================== + +This document describes the consumer interface of the GPIO framework. Note that +it describes the new descriptor-based interface. For a description of the +deprecated integer-based GPIO interface please refer to gpio-legacy.txt. + + +Guidelines for GPIOs consumers +============================== + +Drivers that can't work without standard GPIO calls should have Kconfig entries +that depend on GPIOLIB. The functions that allow a driver to obtain and use +GPIOs are available by including the following file: + + #include <linux/gpio/consumer.h> + +All the functions that work with the descriptor-based GPIO interface are +prefixed with gpiod_. The gpio_ prefix is used for the legacy interface. No +other function in the kernel should use these prefixes. + + +Obtaining and Disposing GPIOs +============================= + +With the descriptor-based interface, GPIOs are identified with an opaque, +non-forgeable handler that must be obtained through a call to one of the +gpiod_get() functions. Like many other kernel subsystems, gpiod_get() takes the +device that will use the GPIO and the function the requested GPIO is supposed to +fulfill: + + struct gpio_desc *gpiod_get(struct device *dev, const char *con_id) + +If a function is implemented by using several GPIOs together (e.g. a simple LED +device that displays digits), an additional index argument can be specified: + + struct gpio_desc *gpiod_get_index(struct device *dev, + const char *con_id, unsigned int idx) + +Both functions return either a valid GPIO descriptor, or an error code checkable +with IS_ERR(). They will never return a NULL pointer. + +Device-managed variants of these functions are also defined: + + struct gpio_desc *devm_gpiod_get(struct device *dev, const char *con_id) + + struct gpio_desc *devm_gpiod_get_index(struct device *dev, + const char *con_id, + unsigned int idx) + +A GPIO descriptor can be disposed of using the gpiod_put() function: + + void gpiod_put(struct gpio_desc *desc) + +It is strictly forbidden to use a descriptor after calling this function. The +device-managed variant is, unsurprisingly: + + void devm_gpiod_put(struct device *dev, struct gpio_desc *desc) + + +Using GPIOs +=========== + +Setting Direction +----------------- +The first thing a driver must do with a GPIO is setting its direction. This is +done by invoking one of the gpiod_direction_*() functions: + + int gpiod_direction_input(struct gpio_desc *desc) + int gpiod_direction_output(struct gpio_desc *desc, int value) + +The return value is zero for success, else a negative errno. It should be +checked, since the get/set calls don't return errors and since misconfiguration +is possible. You should normally issue these calls from a task context. However, +for spinlock-safe GPIOs it is OK to use them before tasking is enabled, as part +of early board setup. + +For output GPIOs, the value provided becomes the initial output value. This +helps avoid signal glitching during system startup. + +A driver can also query the current direction of a GPIO: + + int gpiod_get_direction(const struct gpio_desc *desc) + +This function will return either GPIOF_DIR_IN or GPIOF_DIR_OUT. + +Be aware that there is no default direction for GPIOs. Therefore, **using a GPIO +without setting its direction first is illegal and will result in undefined +behavior!** + + +Spinlock-Safe GPIO Access +------------------------- +Most GPIO controllers can be accessed with memory read/write instructions. Those +don't need to sleep, and can safely be done from inside hard (non-threaded) IRQ +handlers and similar contexts. + +Use the following calls to access GPIOs from an atomic context: + + int gpiod_get_value(const struct gpio_desc *desc); + void gpiod_set_value(struct gpio_desc *desc, int value); + +The values are boolean, zero for low, nonzero for high. When reading the value +of an output pin, the value returned should be what's seen on the pin. That +won't always match the specified output value, because of issues including +open-drain signaling and output latencies. + +The get/set calls do not return errors because "invalid GPIO" should have been +reported earlier from gpiod_direction_*(). However, note that not all platforms +can read the value of output pins; those that can't should always return zero. +Also, using these calls for GPIOs that can't safely be accessed without sleeping +(see below) is an error. + + +GPIO Access That May Sleep +-------------------------- +Some GPIO controllers must be accessed using message based buses like I2C or +SPI. Commands to read or write those GPIO values require waiting to get to the +head of a queue to transmit a command and get its response. This requires +sleeping, which can't be done from inside IRQ handlers. + +Platforms that support this type of GPIO distinguish them from other GPIOs by +returning nonzero from this call: + + int gpiod_cansleep(const struct gpio_desc *desc) + +To access such GPIOs, a different set of accessors is defined: + + int gpiod_get_value_cansleep(const struct gpio_desc *desc) + void gpiod_set_value_cansleep(struct gpio_desc *desc, int value) + +Accessing such GPIOs requires a context which may sleep, for example a threaded +IRQ handler, and those accessors must be used instead of spinlock-safe +accessors without the cansleep() name suffix. + +Other than the fact that these accessors might sleep, and will work on GPIOs +that can't be accessed from hardIRQ handlers, these calls act the same as the +spinlock-safe calls. + + +Active-low State and Raw GPIO Values +------------------------------------ +Device drivers like to manage the logical state of a GPIO, i.e. the value their +device will actually receive, no matter what lies between it and the GPIO line. +In some cases, it might make sense to control the actual GPIO line value. The +following set of calls ignore the active-low property of a GPIO and work on the +raw line value: + + int gpiod_get_raw_value(const struct gpio_desc *desc) + void gpiod_set_raw_value(struct gpio_desc *desc, int value) + int gpiod_get_raw_value_cansleep(const struct gpio_desc *desc) + void gpiod_set_raw_value_cansleep(struct gpio_desc *desc, int value) + +The active-low state of a GPIO can also be queried using the following call: + + int gpiod_is_active_low(const struct gpio_desc *desc) + +Note that these functions should only be used with great moderation ; a driver +should not have to care about the physical line level. + +GPIOs mapped to IRQs +-------------------- +GPIO lines can quite often be used as IRQs. You can get the IRQ number +corresponding to a given GPIO using the following call: + + int gpiod_to_irq(const struct gpio_desc *desc) + +It will return an IRQ number, or an negative errno code if the mapping can't be +done (most likely because that particular GPIO cannot be used as IRQ). It is an +unchecked error to use a GPIO that wasn't set up as an input using +gpiod_direction_input(), or to use an IRQ number that didn't originally come +from gpiod_to_irq(). gpiod_to_irq() is not allowed to sleep. + +Non-error values returned from gpiod_to_irq() can be passed to request_irq() or +free_irq(). They will often be stored into IRQ resources for platform devices, +by the board-specific initialization code. Note that IRQ trigger options are +part of the IRQ interface, e.g. IRQF_TRIGGER_FALLING, as are system wakeup +capabilities. + + +Interacting With the Legacy GPIO Subsystem +========================================== +Many kernel subsystems still handle GPIOs using the legacy integer-based +interface. Although it is strongly encouraged to upgrade them to the safer +descriptor-based API, the following two functions allow you to convert a GPIO +descriptor into the GPIO integer namespace and vice-versa: + + int desc_to_gpio(const struct gpio_desc *desc) + struct gpio_desc *gpio_to_desc(unsigned gpio) + +The GPIO number returned by desc_to_gpio() can be safely used as long as the +GPIO descriptor has not been freed. All the same, a GPIO number passed to +gpio_to_desc() must have been properly acquired, and usage of the returned GPIO +descriptor is only possible after the GPIO number has been released. + +Freeing a GPIO obtained by one API with the other API is forbidden and an +unchecked error. diff --git a/Documentation/gpio/driver.txt b/Documentation/gpio/driver.txt new file mode 100644 index 0000000..9da0bfa --- /dev/null +++ b/Documentation/gpio/driver.txt @@ -0,0 +1,75 @@ +GPIO Descriptor Driver Interface +================================ + +This document serves as a guide for GPIO chip drivers writers. Note that it +describes the new descriptor-based interface. For a description of the +deprecated integer-based GPIO interface please refer to gpio-legacy.txt. + +Each GPIO controller driver needs to include the following header, which defines +the structures used to define a GPIO driver: + + #include <linux/gpio/driver.h> + + +Internal Representation of GPIOs +================================ + +Inside a GPIO driver, individual GPIOs are identified by their hardware number, +which is a unique number between 0 and n, n being the number of GPIOs managed by +the chip. This number is purely internal: the hardware number of a particular +GPIO descriptor is never made visible outside of the driver. + +On top of this internal number, each GPIO also need to have a global number in +the integer GPIO namespace so that it can be used with the legacy GPIO +interface. Each chip must thus have a "base" number (which can be automatically +assigned), and for each GPIO the global number will be (base + hardware number). +Although the integer representation is considered deprecated, it still has many +users and thus needs to be maintained. + +So for example one platform could use numbers 32-159 for GPIOs, with a +controller defining 128 GPIOs at a "base" of 32 ; while another platform uses +numbers 0..63 with one set of GPIO controllers, 64-79 with another type of GPIO +controller, and on one particular board 80-95 with an FPGA. The numbers need not +be contiguous; either of those platforms could also use numbers 2000-2063 to +identify GPIOs in a bank of I2C GPIO expanders. + + +Controller Drivers: gpio_chip +============================= + +In the gpiolib framework each GPIO controller is packaged as a "struct +gpio_chip" (see linux/gpio/driver.h for its complete definition) with members +common to each controller of that type: + + - methods to establish GPIO direction + - methods used to access GPIO values + - method to return the IRQ number associated to a given GPIO + - flag saying whether calls to its methods may sleep + - optional debugfs dump method (showing extra state like pullup config) + - optional base number (will be automatically assigned if omitted) + - label for diagnostics and GPIOs mapping using platform data + +The code implementing a gpio_chip should support multiple instances of the +controller, possibly using the driver model. That code will configure each +gpio_chip and issue gpiochip_add(). Removing a GPIO controller should be rare; +use gpiochip_remove() when it is unavoidable. + +Most often a gpio_chip is part of an instance-specific structure with state not +exposed by the GPIO interfaces, such as addressing, power management, and more. +Chips such as codecs will have complex non-GPIO state. + +Any debugfs dump method should normally ignore signals which haven't been +requested as GPIOs. They can use gpiochip_is_requested(), which returns either +NULL or the label associated with that GPIO when it was requested. + +Locking IRQ usage +----------------- +Input GPIOs can be used as IRQ signals. When this happens, a driver is requested +to mark the GPIO as being used as an IRQ: + + int gpiod_lock_as_irq(struct gpio_desc *desc) + +This will prevent the use of non-irq related GPIO APIs until the GPIO IRQ lock +is released: + + void gpiod_unlock_as_irq(struct gpio_desc *desc) diff --git a/Documentation/gpio.txt b/Documentation/gpio/gpio-legacy.txt index 6f83fa9..6f83fa9 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio/gpio-legacy.txt diff --git a/Documentation/gpio/gpio.txt b/Documentation/gpio/gpio.txt new file mode 100644 index 0000000..cd9b356 --- /dev/null +++ b/Documentation/gpio/gpio.txt @@ -0,0 +1,119 @@ +GPIO Interfaces +=============== + +The documents in this directory give detailed instructions on how to access +GPIOs in drivers, and how to write a driver for a device that provides GPIOs +itself. + +Due to the history of GPIO interfaces in the kernel, there are two different +ways to obtain and use GPIOs: + + - The descriptor-based interface is the preferred way to manipulate GPIOs, +and is described by all the files in this directory excepted gpio-legacy.txt. + - The legacy integer-based interface which is considered deprecated (but still +usable for compatibility reasons) is documented in gpio-legacy.txt. + +The remainder of this document applies to the new descriptor-based interface. +gpio-legacy.txt contains the same information applied to the legacy +integer-based interface. + + +What is a GPIO? +=============== + +A "General Purpose Input/Output" (GPIO) is a flexible software-controlled +digital signal. They are provided from many kinds of chip, and are familiar +to Linux developers working with embedded and custom hardware. Each GPIO +represents a bit connected to a particular pin, or "ball" on Ball Grid Array +(BGA) packages. Board schematics show which external hardware connects to +which GPIOs. Drivers can be written generically, so that board setup code +passes such pin configuration data to drivers. + +System-on-Chip (SOC) processors heavily rely on GPIOs. In some cases, every +non-dedicated pin can be configured as a GPIO; and most chips have at least +several dozen of them. Programmable logic devices (like FPGAs) can easily +provide GPIOs; multifunction chips like power managers, and audio codecs +often have a few such pins to help with pin scarcity on SOCs; and there are +also "GPIO Expander" chips that connect using the I2C or SPI serial buses. +Most PC southbridges have a few dozen GPIO-capable pins (with only the BIOS +firmware knowing how they're used). + +The exact capabilities of GPIOs vary between systems. Common options: + + - Output values are writable (high=1, low=0). Some chips also have + options about how that value is driven, so that for example only one + value might be driven, supporting "wire-OR" and similar schemes for the + other value (notably, "open drain" signaling). + + - Input values are likewise readable (1, 0). Some chips support readback + of pins configured as "output", which is very useful in such "wire-OR" + cases (to support bidirectional signaling). GPIO controllers may have + input de-glitch/debounce logic, sometimes with software controls. + + - Inputs can often be used as IRQ signals, often edge triggered but + sometimes level triggered. Such IRQs may be configurable as system + wakeup events, to wake the system from a low power state. + + - Usually a GPIO will be configurable as either input or output, as needed + by different product boards; single direction ones exist too. + + - Most GPIOs can be accessed while holding spinlocks, but those accessed + through a serial bus normally can't. Some systems support both types. + +On a given board each GPIO is used for one specific purpose like monitoring +MMC/SD card insertion/removal, detecting card write-protect status, driving +a LED, configuring a transceiver, bit-banging a serial bus, poking a hardware +watchdog, sensing a switch, and so on. + + +Common GPIO Properties +====================== + +These properties are met through all the other documents of the GPIO interface +and it is useful to understand them, especially if you need to define GPIO +mappings. + +Active-High and Active-Low +-------------------------- +It is natural to assume that a GPIO is "active" when its output signal is 1 +("high"), and inactive when it is 0 ("low"). However in practice the signal of a +GPIO may be inverted before is reaches its destination, or a device could decide +to have different conventions about what "active" means. Such decisions should +be transparent to device drivers, therefore it is possible to define a GPIO as +being either active-high ("1" means "active", the default) or active-low ("0" +means "active") so that drivers only need to worry about the logical signal and +not about what happens at the line level. + +Open Drain and Open Source +-------------------------- +Sometimes shared signals need to use "open drain" (where only the low signal +level is actually driven), or "open source" (where only the high signal level is +driven) signaling. That term applies to CMOS transistors; "open collector" is +used for TTL. A pullup or pulldown resistor causes the high or low signal level. +This is sometimes called a "wire-AND"; or more practically, from the negative +logic (low=true) perspective this is a "wire-OR". + +One common example of an open drain signal is a shared active-low IRQ line. +Also, bidirectional data bus signals sometimes use open drain signals. + +Some GPIO controllers directly support open drain and open source outputs; many +don't. When you need open drain signaling but your hardware doesn't directly +support it, there's a common idiom you can use to emulate it with any GPIO pin +that can be used as either an input or an output: + + LOW: gpiod_direction_output(gpio, 0) ... this drives the signal and overrides + the pullup. + + HIGH: gpiod_direction_input(gpio) ... this turns off the output, so the pullup + (or some other device) controls the signal. + +The same logic can be applied to emulate open source signaling, by driving the +high signal and configuring the GPIO as input for low. This open drain/open +source emulation can be handled transparently by the GPIO framework. + +If you are "driving" the signal high but gpiod_get_value(gpio) reports a low +value (after the appropriate rise time passes), you know some other component is +driving the shared signal low. That's not necessarily an error. As one common +example, that's how I2C clocks are stretched: a slave that needs a slower clock +delays the rising edge of SCK, and the I2C master adjusts its signaling rate +accordingly. diff --git a/Documentation/gpio/sysfs.txt b/Documentation/gpio/sysfs.txt new file mode 100644 index 0000000..c2c3a97 --- /dev/null +++ b/Documentation/gpio/sysfs.txt @@ -0,0 +1,155 @@ +GPIO Sysfs Interface for Userspace +================================== + +Platforms which use the "gpiolib" implementors framework may choose to +configure a sysfs user interface to GPIOs. This is different from the +debugfs interface, since it provides control over GPIO direction and +value instead of just showing a gpio state summary. Plus, it could be +present on production systems without debugging support. + +Given appropriate hardware documentation for the system, userspace could +know for example that GPIO #23 controls the write protect line used to +protect boot loader segments in flash memory. System upgrade procedures +may need to temporarily remove that protection, first importing a GPIO, +then changing its output state, then updating the code before re-enabling +the write protection. In normal use, GPIO #23 would never be touched, +and the kernel would have no need to know about it. + +Again depending on appropriate hardware documentation, on some systems +userspace GPIO can be used to determine system configuration data that +standard kernels won't know about. And for some tasks, simple userspace +GPIO drivers could be all that the system really needs. + +Note that standard kernel drivers exist for common "LEDs and Buttons" +GPIO tasks: "leds-gpio" and "gpio_keys", respectively. Use those +instead of talking directly to the GPIOs; they integrate with kernel +frameworks better than your userspace code could. + + +Paths in Sysfs +-------------- +There are three kinds of entry in /sys/class/gpio: + + - Control interfaces used to get userspace control over GPIOs; + + - GPIOs themselves; and + + - GPIO controllers ("gpio_chip" instances). + +That's in addition to standard files including the "device" symlink. + +The control interfaces are write-only: + + /sys/class/gpio/ + + "export" ... Userspace may ask the kernel to export control of + a GPIO to userspace by writing its number to this file. + + Example: "echo 19 > export" will create a "gpio19" node + for GPIO #19, if that's not requested by kernel code. + + "unexport" ... Reverses the effect of exporting to userspace. + + Example: "echo 19 > unexport" will remove a "gpio19" + node exported using the "export" file. + +GPIO signals have paths like /sys/class/gpio/gpio42/ (for GPIO #42) +and have the following read/write attributes: + + /sys/class/gpio/gpioN/ + + "direction" ... reads as either "in" or "out". This value may + normally be written. Writing as "out" defaults to + initializing the value as low. To ensure glitch free + operation, values "low" and "high" may be written to + configure the GPIO as an output with that initial value. + + Note that this attribute *will not exist* if the kernel + doesn't support changing the direction of a GPIO, or + it was exported by kernel code that didn't explicitly + allow userspace to reconfigure this GPIO's direction. + + "value" ... reads as either 0 (low) or 1 (high). If the GPIO + is configured as an output, this value may be written; + any nonzero value is treated as high. + + If the pin can be configured as interrupt-generating interrupt + and if it has been configured to generate interrupts (see the + description of "edge"), you can poll(2) on that file and + poll(2) will return whenever the interrupt was triggered. If + you use poll(2), set the events POLLPRI and POLLERR. If you + use select(2), set the file descriptor in exceptfds. After + poll(2) returns, either lseek(2) to the beginning of the sysfs + file and read the new value or close the file and re-open it + to read the value. + + "edge" ... reads as either "none", "rising", "falling", or + "both". Write these strings to select the signal edge(s) + that will make poll(2) on the "value" file return. + + This file exists only if the pin can be configured as an + interrupt generating input pin. + + "active_low" ... reads as either 0 (false) or 1 (true). Write + any nonzero value to invert the value attribute both + for reading and writing. Existing and subsequent + poll(2) support configuration via the edge attribute + for "rising" and "falling" edges will follow this + setting. + +GPIO controllers have paths like /sys/class/gpio/gpiochip42/ (for the +controller implementing GPIOs starting at #42) and have the following +read-only attributes: + + /sys/class/gpio/gpiochipN/ + + "base" ... same as N, the first GPIO managed by this chip + + "label" ... provided for diagnostics (not always unique) + + "ngpio" ... how many GPIOs this manges (N to N + ngpio - 1) + +Board documentation should in most cases cover what GPIOs are used for +what purposes. However, those numbers are not always stable; GPIOs on +a daughtercard might be different depending on the base board being used, +or other cards in the stack. In such cases, you may need to use the +gpiochip nodes (possibly in conjunction with schematics) to determine +the correct GPIO number to use for a given signal. + + +Exporting from Kernel code +-------------------------- +Kernel code can explicitly manage exports of GPIOs which have already been +requested using gpio_request(): + + /* export the GPIO to userspace */ + int gpiod_export(struct gpio_desc *desc, bool direction_may_change); + + /* reverse gpio_export() */ + void gpiod_unexport(struct gpio_desc *desc); + + /* create a sysfs link to an exported GPIO node */ + int gpiod_export_link(struct device *dev, const char *name, + struct gpio_desc *desc); + + /* change the polarity of a GPIO node in sysfs */ + int gpiod_sysfs_set_active_low(struct gpio_desc *desc, int value); + +After a kernel driver requests a GPIO, it may only be made available in +the sysfs interface by gpiod_export(). The driver can control whether the +signal direction may change. This helps drivers prevent userspace code +from accidentally clobbering important system state. + +This explicit exporting can help with debugging (by making some kinds +of experiments easier), or can provide an always-there interface that's +suitable for documenting as part of a board support package. + +After the GPIO has been exported, gpiod_export_link() allows creating +symlinks from elsewhere in sysfs to the GPIO sysfs node. Drivers can +use this to provide the interface under their own device in sysfs with +a descriptive name. + +Drivers can use gpiod_sysfs_set_active_low() to hide GPIO line polarity +differences between boards from user space. Polarity change can be done both +before and after gpiod_export(), and previously enabled poll(2) support for +either rising or falling edge will be reconfigured to follow this setting. diff --git a/Documentation/mic/mpssd/mpssd.c b/Documentation/mic/mpssd/mpssd.c index 0c980ad..4d17487 100644 --- a/Documentation/mic/mpssd/mpssd.c +++ b/Documentation/mic/mpssd/mpssd.c @@ -313,7 +313,7 @@ static struct mic_device_desc *get_device_desc(struct mic_info *mic, int type) int i; void *dp = get_dp(mic, type); - for (i = mic_aligned_size(struct mic_bootparam); i < PAGE_SIZE; + for (i = sizeof(struct mic_bootparam); i < PAGE_SIZE; i += mic_total_desc_size(d)) { d = dp + i; @@ -445,8 +445,8 @@ init_vr(struct mic_info *mic, int fd, int type, __func__, mic->name, vr0->va, vr0->info, vr_size, vring_size(MIC_VRING_ENTRIES, MIC_VIRTIO_RING_ALIGN)); mpsslog("magic 0x%x expected 0x%x\n", - vr0->info->magic, MIC_MAGIC + type); - assert(vr0->info->magic == MIC_MAGIC + type); + le32toh(vr0->info->magic), MIC_MAGIC + type); + assert(le32toh(vr0->info->magic) == MIC_MAGIC + type); if (vr1) { vr1->va = (struct mic_vring *) &va[MIC_DEVICE_PAGE_END + vr_size]; @@ -458,8 +458,8 @@ init_vr(struct mic_info *mic, int fd, int type, __func__, mic->name, vr1->va, vr1->info, vr_size, vring_size(MIC_VRING_ENTRIES, MIC_VIRTIO_RING_ALIGN)); mpsslog("magic 0x%x expected 0x%x\n", - vr1->info->magic, MIC_MAGIC + type + 1); - assert(vr1->info->magic == MIC_MAGIC + type + 1); + le32toh(vr1->info->magic), MIC_MAGIC + type + 1); + assert(le32toh(vr1->info->magic) == MIC_MAGIC + type + 1); } done: return va; @@ -520,7 +520,7 @@ static void * virtio_net(void *arg) { static __u8 vnet_hdr[2][sizeof(struct virtio_net_hdr)]; - static __u8 vnet_buf[2][MAX_NET_PKT_SIZE] __aligned(64); + static __u8 vnet_buf[2][MAX_NET_PKT_SIZE] __attribute__ ((aligned(64))); struct iovec vnet_iov[2][2] = { { { .iov_base = vnet_hdr[0], .iov_len = sizeof(vnet_hdr[0]) }, { .iov_base = vnet_buf[0], .iov_len = sizeof(vnet_buf[0]) } }, @@ -1412,6 +1412,12 @@ mic_config(void *arg) } do { + ret = lseek(fd, 0, SEEK_SET); + if (ret < 0) { + mpsslog("%s: Failed to seek to file start '%s': %s\n", + mic->name, pathname, strerror(errno)); + goto close_error1; + } ret = read(fd, value, sizeof(value)); if (ret < 0) { mpsslog("%s: Failed to read sysfs entry '%s': %s\n", |
