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Diffstat (limited to 'kernel/include/linux/spi/spi.h')
| -rw-r--r-- | kernel/include/linux/spi/spi.h | 1056 |
1 files changed, 1056 insertions, 0 deletions
diff --git a/kernel/include/linux/spi/spi.h b/kernel/include/linux/spi/spi.h new file mode 100644 index 000000000..d67307234 --- /dev/null +++ b/kernel/include/linux/spi/spi.h @@ -0,0 +1,1056 @@ +/* + * Copyright (C) 2005 David Brownell + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#ifndef __LINUX_SPI_H +#define __LINUX_SPI_H + +#include <linux/device.h> +#include <linux/mod_devicetable.h> +#include <linux/slab.h> +#include <linux/kthread.h> +#include <linux/completion.h> +#include <linux/scatterlist.h> + +struct dma_chan; + +/* + * INTERFACES between SPI master-side drivers and SPI infrastructure. + * (There's no SPI slave support for Linux yet...) + */ +extern struct bus_type spi_bus_type; + +/** + * struct spi_device - Master side proxy for an SPI slave device + * @dev: Driver model representation of the device. + * @master: SPI controller used with the device. + * @max_speed_hz: Maximum clock rate to be used with this chip + * (on this board); may be changed by the device's driver. + * The spi_transfer.speed_hz can override this for each transfer. + * @chip_select: Chipselect, distinguishing chips handled by @master. + * @mode: The spi mode defines how data is clocked out and in. + * This may be changed by the device's driver. + * The "active low" default for chipselect mode can be overridden + * (by specifying SPI_CS_HIGH) as can the "MSB first" default for + * each word in a transfer (by specifying SPI_LSB_FIRST). + * @bits_per_word: Data transfers involve one or more words; word sizes + * like eight or 12 bits are common. In-memory wordsizes are + * powers of two bytes (e.g. 20 bit samples use 32 bits). + * This may be changed by the device's driver, or left at the + * default (0) indicating protocol words are eight bit bytes. + * The spi_transfer.bits_per_word can override this for each transfer. + * @irq: Negative, or the number passed to request_irq() to receive + * interrupts from this device. + * @controller_state: Controller's runtime state + * @controller_data: Board-specific definitions for controller, such as + * FIFO initialization parameters; from board_info.controller_data + * @modalias: Name of the driver to use with this device, or an alias + * for that name. This appears in the sysfs "modalias" attribute + * for driver coldplugging, and in uevents used for hotplugging + * @cs_gpio: gpio number of the chipselect line (optional, -ENOENT when + * when not using a GPIO line) + * + * A @spi_device is used to interchange data between an SPI slave + * (usually a discrete chip) and CPU memory. + * + * In @dev, the platform_data is used to hold information about this + * device that's meaningful to the device's protocol driver, but not + * to its controller. One example might be an identifier for a chip + * variant with slightly different functionality; another might be + * information about how this particular board wires the chip's pins. + */ +struct spi_device { + struct device dev; + struct spi_master *master; + u32 max_speed_hz; + u8 chip_select; + u8 bits_per_word; + u16 mode; +#define SPI_CPHA 0x01 /* clock phase */ +#define SPI_CPOL 0x02 /* clock polarity */ +#define SPI_MODE_0 (0|0) /* (original MicroWire) */ +#define SPI_MODE_1 (0|SPI_CPHA) +#define SPI_MODE_2 (SPI_CPOL|0) +#define SPI_MODE_3 (SPI_CPOL|SPI_CPHA) +#define SPI_CS_HIGH 0x04 /* chipselect active high? */ +#define SPI_LSB_FIRST 0x08 /* per-word bits-on-wire */ +#define SPI_3WIRE 0x10 /* SI/SO signals shared */ +#define SPI_LOOP 0x20 /* loopback mode */ +#define SPI_NO_CS 0x40 /* 1 dev/bus, no chipselect */ +#define SPI_READY 0x80 /* slave pulls low to pause */ +#define SPI_TX_DUAL 0x100 /* transmit with 2 wires */ +#define SPI_TX_QUAD 0x200 /* transmit with 4 wires */ +#define SPI_RX_DUAL 0x400 /* receive with 2 wires */ +#define SPI_RX_QUAD 0x800 /* receive with 4 wires */ + int irq; + void *controller_state; + void *controller_data; + char modalias[SPI_NAME_SIZE]; + int cs_gpio; /* chip select gpio */ + + /* + * likely need more hooks for more protocol options affecting how + * the controller talks to each chip, like: + * - memory packing (12 bit samples into low bits, others zeroed) + * - priority + * - drop chipselect after each word + * - chipselect delays + * - ... + */ +}; + +static inline struct spi_device *to_spi_device(struct device *dev) +{ + return dev ? container_of(dev, struct spi_device, dev) : NULL; +} + +/* most drivers won't need to care about device refcounting */ +static inline struct spi_device *spi_dev_get(struct spi_device *spi) +{ + return (spi && get_device(&spi->dev)) ? spi : NULL; +} + +static inline void spi_dev_put(struct spi_device *spi) +{ + if (spi) + put_device(&spi->dev); +} + +/* ctldata is for the bus_master driver's runtime state */ +static inline void *spi_get_ctldata(struct spi_device *spi) +{ + return spi->controller_state; +} + +static inline void spi_set_ctldata(struct spi_device *spi, void *state) +{ + spi->controller_state = state; +} + +/* device driver data */ + +static inline void spi_set_drvdata(struct spi_device *spi, void *data) +{ + dev_set_drvdata(&spi->dev, data); +} + +static inline void *spi_get_drvdata(struct spi_device *spi) +{ + return dev_get_drvdata(&spi->dev); +} + +struct spi_message; +struct spi_transfer; + +/** + * struct spi_driver - Host side "protocol" driver + * @id_table: List of SPI devices supported by this driver + * @probe: Binds this driver to the spi device. Drivers can verify + * that the device is actually present, and may need to configure + * characteristics (such as bits_per_word) which weren't needed for + * the initial configuration done during system setup. + * @remove: Unbinds this driver from the spi device + * @shutdown: Standard shutdown callback used during system state + * transitions such as powerdown/halt and kexec + * @driver: SPI device drivers should initialize the name and owner + * field of this structure. + * + * This represents the kind of device driver that uses SPI messages to + * interact with the hardware at the other end of a SPI link. It's called + * a "protocol" driver because it works through messages rather than talking + * directly to SPI hardware (which is what the underlying SPI controller + * driver does to pass those messages). These protocols are defined in the + * specification for the device(s) supported by the driver. + * + * As a rule, those device protocols represent the lowest level interface + * supported by a driver, and it will support upper level interfaces too. + * Examples of such upper levels include frameworks like MTD, networking, + * MMC, RTC, filesystem character device nodes, and hardware monitoring. + */ +struct spi_driver { + const struct spi_device_id *id_table; + int (*probe)(struct spi_device *spi); + int (*remove)(struct spi_device *spi); + void (*shutdown)(struct spi_device *spi); + struct device_driver driver; +}; + +static inline struct spi_driver *to_spi_driver(struct device_driver *drv) +{ + return drv ? container_of(drv, struct spi_driver, driver) : NULL; +} + +extern int spi_register_driver(struct spi_driver *sdrv); + +/** + * spi_unregister_driver - reverse effect of spi_register_driver + * @sdrv: the driver to unregister + * Context: can sleep + */ +static inline void spi_unregister_driver(struct spi_driver *sdrv) +{ + if (sdrv) + driver_unregister(&sdrv->driver); +} + +/** + * module_spi_driver() - Helper macro for registering a SPI driver + * @__spi_driver: spi_driver struct + * + * Helper macro for SPI drivers which do not do anything special in module + * init/exit. This eliminates a lot of boilerplate. Each module may only + * use this macro once, and calling it replaces module_init() and module_exit() + */ +#define module_spi_driver(__spi_driver) \ + module_driver(__spi_driver, spi_register_driver, \ + spi_unregister_driver) + +/** + * struct spi_master - interface to SPI master controller + * @dev: device interface to this driver + * @list: link with the global spi_master list + * @bus_num: board-specific (and often SOC-specific) identifier for a + * given SPI controller. + * @num_chipselect: chipselects are used to distinguish individual + * SPI slaves, and are numbered from zero to num_chipselects. + * each slave has a chipselect signal, but it's common that not + * every chipselect is connected to a slave. + * @dma_alignment: SPI controller constraint on DMA buffers alignment. + * @mode_bits: flags understood by this controller driver + * @bits_per_word_mask: A mask indicating which values of bits_per_word are + * supported by the driver. Bit n indicates that a bits_per_word n+1 is + * supported. If set, the SPI core will reject any transfer with an + * unsupported bits_per_word. If not set, this value is simply ignored, + * and it's up to the individual driver to perform any validation. + * @min_speed_hz: Lowest supported transfer speed + * @max_speed_hz: Highest supported transfer speed + * @flags: other constraints relevant to this driver + * @bus_lock_spinlock: spinlock for SPI bus locking + * @bus_lock_mutex: mutex for SPI bus locking + * @bus_lock_flag: indicates that the SPI bus is locked for exclusive use + * @setup: updates the device mode and clocking records used by a + * device's SPI controller; protocol code may call this. This + * must fail if an unrecognized or unsupported mode is requested. + * It's always safe to call this unless transfers are pending on + * the device whose settings are being modified. + * @transfer: adds a message to the controller's transfer queue. + * @cleanup: frees controller-specific state + * @can_dma: determine whether this master supports DMA + * @queued: whether this master is providing an internal message queue + * @kworker: thread struct for message pump + * @kworker_task: pointer to task for message pump kworker thread + * @pump_messages: work struct for scheduling work to the message pump + * @queue_lock: spinlock to syncronise access to message queue + * @queue: message queue + * @idling: the device is entering idle state + * @cur_msg: the currently in-flight message + * @cur_msg_prepared: spi_prepare_message was called for the currently + * in-flight message + * @cur_msg_mapped: message has been mapped for DMA + * @xfer_completion: used by core transfer_one_message() + * @busy: message pump is busy + * @running: message pump is running + * @rt: whether this queue is set to run as a realtime task + * @auto_runtime_pm: the core should ensure a runtime PM reference is held + * while the hardware is prepared, using the parent + * device for the spidev + * @max_dma_len: Maximum length of a DMA transfer for the device. + * @prepare_transfer_hardware: a message will soon arrive from the queue + * so the subsystem requests the driver to prepare the transfer hardware + * by issuing this call + * @transfer_one_message: the subsystem calls the driver to transfer a single + * message while queuing transfers that arrive in the meantime. When the + * driver is finished with this message, it must call + * spi_finalize_current_message() so the subsystem can issue the next + * message + * @unprepare_transfer_hardware: there are currently no more messages on the + * queue so the subsystem notifies the driver that it may relax the + * hardware by issuing this call + * @set_cs: set the logic level of the chip select line. May be called + * from interrupt context. + * @prepare_message: set up the controller to transfer a single message, + * for example doing DMA mapping. Called from threaded + * context. + * @transfer_one: transfer a single spi_transfer. + * - return 0 if the transfer is finished, + * - return 1 if the transfer is still in progress. When + * the driver is finished with this transfer it must + * call spi_finalize_current_transfer() so the subsystem + * can issue the next transfer. Note: transfer_one and + * transfer_one_message are mutually exclusive; when both + * are set, the generic subsystem does not call your + * transfer_one callback. + * @handle_err: the subsystem calls the driver to handle an error that occurs + * in the generic implementation of transfer_one_message(). + * @unprepare_message: undo any work done by prepare_message(). + * @cs_gpios: Array of GPIOs to use as chip select lines; one per CS + * number. Any individual value may be -ENOENT for CS lines that + * are not GPIOs (driven by the SPI controller itself). + * @dma_tx: DMA transmit channel + * @dma_rx: DMA receive channel + * @dummy_rx: dummy receive buffer for full-duplex devices + * @dummy_tx: dummy transmit buffer for full-duplex devices + * + * Each SPI master controller can communicate with one or more @spi_device + * children. These make a small bus, sharing MOSI, MISO and SCK signals + * but not chip select signals. Each device may be configured to use a + * different clock rate, since those shared signals are ignored unless + * the chip is selected. + * + * The driver for an SPI controller manages access to those devices through + * a queue of spi_message transactions, copying data between CPU memory and + * an SPI slave device. For each such message it queues, it calls the + * message's completion function when the transaction completes. + */ +struct spi_master { + struct device dev; + + struct list_head list; + + /* other than negative (== assign one dynamically), bus_num is fully + * board-specific. usually that simplifies to being SOC-specific. + * example: one SOC has three SPI controllers, numbered 0..2, + * and one board's schematics might show it using SPI-2. software + * would normally use bus_num=2 for that controller. + */ + s16 bus_num; + + /* chipselects will be integral to many controllers; some others + * might use board-specific GPIOs. + */ + u16 num_chipselect; + + /* some SPI controllers pose alignment requirements on DMAable + * buffers; let protocol drivers know about these requirements. + */ + u16 dma_alignment; + + /* spi_device.mode flags understood by this controller driver */ + u16 mode_bits; + + /* bitmask of supported bits_per_word for transfers */ + u32 bits_per_word_mask; +#define SPI_BPW_MASK(bits) BIT((bits) - 1) +#define SPI_BIT_MASK(bits) (((bits) == 32) ? ~0U : (BIT(bits) - 1)) +#define SPI_BPW_RANGE_MASK(min, max) (SPI_BIT_MASK(max) - SPI_BIT_MASK(min - 1)) + + /* limits on transfer speed */ + u32 min_speed_hz; + u32 max_speed_hz; + + /* other constraints relevant to this driver */ + u16 flags; +#define SPI_MASTER_HALF_DUPLEX BIT(0) /* can't do full duplex */ +#define SPI_MASTER_NO_RX BIT(1) /* can't do buffer read */ +#define SPI_MASTER_NO_TX BIT(2) /* can't do buffer write */ +#define SPI_MASTER_MUST_RX BIT(3) /* requires rx */ +#define SPI_MASTER_MUST_TX BIT(4) /* requires tx */ + + /* lock and mutex for SPI bus locking */ + spinlock_t bus_lock_spinlock; + struct mutex bus_lock_mutex; + + /* flag indicating that the SPI bus is locked for exclusive use */ + bool bus_lock_flag; + + /* Setup mode and clock, etc (spi driver may call many times). + * + * IMPORTANT: this may be called when transfers to another + * device are active. DO NOT UPDATE SHARED REGISTERS in ways + * which could break those transfers. + */ + int (*setup)(struct spi_device *spi); + + /* bidirectional bulk transfers + * + * + The transfer() method may not sleep; its main role is + * just to add the message to the queue. + * + For now there's no remove-from-queue operation, or + * any other request management + * + To a given spi_device, message queueing is pure fifo + * + * + The master's main job is to process its message queue, + * selecting a chip then transferring data + * + If there are multiple spi_device children, the i/o queue + * arbitration algorithm is unspecified (round robin, fifo, + * priority, reservations, preemption, etc) + * + * + Chipselect stays active during the entire message + * (unless modified by spi_transfer.cs_change != 0). + * + The message transfers use clock and SPI mode parameters + * previously established by setup() for this device + */ + int (*transfer)(struct spi_device *spi, + struct spi_message *mesg); + + /* called on release() to free memory provided by spi_master */ + void (*cleanup)(struct spi_device *spi); + + /* + * Used to enable core support for DMA handling, if can_dma() + * exists and returns true then the transfer will be mapped + * prior to transfer_one() being called. The driver should + * not modify or store xfer and dma_tx and dma_rx must be set + * while the device is prepared. + */ + bool (*can_dma)(struct spi_master *master, + struct spi_device *spi, + struct spi_transfer *xfer); + + /* + * These hooks are for drivers that want to use the generic + * master transfer queueing mechanism. If these are used, the + * transfer() function above must NOT be specified by the driver. + * Over time we expect SPI drivers to be phased over to this API. + */ + bool queued; + struct kthread_worker kworker; + struct task_struct *kworker_task; + struct kthread_work pump_messages; + spinlock_t queue_lock; + struct list_head queue; + struct spi_message *cur_msg; + bool idling; + bool busy; + bool running; + bool rt; + bool auto_runtime_pm; + bool cur_msg_prepared; + bool cur_msg_mapped; + struct completion xfer_completion; + size_t max_dma_len; + + int (*prepare_transfer_hardware)(struct spi_master *master); + int (*transfer_one_message)(struct spi_master *master, + struct spi_message *mesg); + int (*unprepare_transfer_hardware)(struct spi_master *master); + int (*prepare_message)(struct spi_master *master, + struct spi_message *message); + int (*unprepare_message)(struct spi_master *master, + struct spi_message *message); + + /* + * These hooks are for drivers that use a generic implementation + * of transfer_one_message() provied by the core. + */ + void (*set_cs)(struct spi_device *spi, bool enable); + int (*transfer_one)(struct spi_master *master, struct spi_device *spi, + struct spi_transfer *transfer); + void (*handle_err)(struct spi_master *master, + struct spi_message *message); + + /* gpio chip select */ + int *cs_gpios; + + /* DMA channels for use with core dmaengine helpers */ + struct dma_chan *dma_tx; + struct dma_chan *dma_rx; + + /* dummy data for full duplex devices */ + void *dummy_rx; + void *dummy_tx; +}; + +static inline void *spi_master_get_devdata(struct spi_master *master) +{ + return dev_get_drvdata(&master->dev); +} + +static inline void spi_master_set_devdata(struct spi_master *master, void *data) +{ + dev_set_drvdata(&master->dev, data); +} + +static inline struct spi_master *spi_master_get(struct spi_master *master) +{ + if (!master || !get_device(&master->dev)) + return NULL; + return master; +} + +static inline void spi_master_put(struct spi_master *master) +{ + if (master) + put_device(&master->dev); +} + +/* PM calls that need to be issued by the driver */ +extern int spi_master_suspend(struct spi_master *master); +extern int spi_master_resume(struct spi_master *master); + +/* Calls the driver make to interact with the message queue */ +extern struct spi_message *spi_get_next_queued_message(struct spi_master *master); +extern void spi_finalize_current_message(struct spi_master *master); +extern void spi_finalize_current_transfer(struct spi_master *master); + +/* the spi driver core manages memory for the spi_master classdev */ +extern struct spi_master * +spi_alloc_master(struct device *host, unsigned size); + +extern int spi_register_master(struct spi_master *master); +extern int devm_spi_register_master(struct device *dev, + struct spi_master *master); +extern void spi_unregister_master(struct spi_master *master); + +extern struct spi_master *spi_busnum_to_master(u16 busnum); + +/*---------------------------------------------------------------------------*/ + +/* + * I/O INTERFACE between SPI controller and protocol drivers + * + * Protocol drivers use a queue of spi_messages, each transferring data + * between the controller and memory buffers. + * + * The spi_messages themselves consist of a series of read+write transfer + * segments. Those segments always read the same number of bits as they + * write; but one or the other is easily ignored by passing a null buffer + * pointer. (This is unlike most types of I/O API, because SPI hardware + * is full duplex.) + * + * NOTE: Allocation of spi_transfer and spi_message memory is entirely + * up to the protocol driver, which guarantees the integrity of both (as + * well as the data buffers) for as long as the message is queued. + */ + +/** + * struct spi_transfer - a read/write buffer pair + * @tx_buf: data to be written (dma-safe memory), or NULL + * @rx_buf: data to be read (dma-safe memory), or NULL + * @tx_dma: DMA address of tx_buf, if @spi_message.is_dma_mapped + * @rx_dma: DMA address of rx_buf, if @spi_message.is_dma_mapped + * @tx_nbits: number of bits used for writing. If 0 the default + * (SPI_NBITS_SINGLE) is used. + * @rx_nbits: number of bits used for reading. If 0 the default + * (SPI_NBITS_SINGLE) is used. + * @len: size of rx and tx buffers (in bytes) + * @speed_hz: Select a speed other than the device default for this + * transfer. If 0 the default (from @spi_device) is used. + * @bits_per_word: select a bits_per_word other than the device default + * for this transfer. If 0 the default (from @spi_device) is used. + * @cs_change: affects chipselect after this transfer completes + * @delay_usecs: microseconds to delay after this transfer before + * (optionally) changing the chipselect status, then starting + * the next transfer or completing this @spi_message. + * @transfer_list: transfers are sequenced through @spi_message.transfers + * @tx_sg: Scatterlist for transmit, currently not for client use + * @rx_sg: Scatterlist for receive, currently not for client use + * + * SPI transfers always write the same number of bytes as they read. + * Protocol drivers should always provide @rx_buf and/or @tx_buf. + * In some cases, they may also want to provide DMA addresses for + * the data being transferred; that may reduce overhead, when the + * underlying driver uses dma. + * + * If the transmit buffer is null, zeroes will be shifted out + * while filling @rx_buf. If the receive buffer is null, the data + * shifted in will be discarded. Only "len" bytes shift out (or in). + * It's an error to try to shift out a partial word. (For example, by + * shifting out three bytes with word size of sixteen or twenty bits; + * the former uses two bytes per word, the latter uses four bytes.) + * + * In-memory data values are always in native CPU byte order, translated + * from the wire byte order (big-endian except with SPI_LSB_FIRST). So + * for example when bits_per_word is sixteen, buffers are 2N bytes long + * (@len = 2N) and hold N sixteen bit words in CPU byte order. + * + * When the word size of the SPI transfer is not a power-of-two multiple + * of eight bits, those in-memory words include extra bits. In-memory + * words are always seen by protocol drivers as right-justified, so the + * undefined (rx) or unused (tx) bits are always the most significant bits. + * + * All SPI transfers start with the relevant chipselect active. Normally + * it stays selected until after the last transfer in a message. Drivers + * can affect the chipselect signal using cs_change. + * + * (i) If the transfer isn't the last one in the message, this flag is + * used to make the chipselect briefly go inactive in the middle of the + * message. Toggling chipselect in this way may be needed to terminate + * a chip command, letting a single spi_message perform all of group of + * chip transactions together. + * + * (ii) When the transfer is the last one in the message, the chip may + * stay selected until the next transfer. On multi-device SPI busses + * with nothing blocking messages going to other devices, this is just + * a performance hint; starting a message to another device deselects + * this one. But in other cases, this can be used to ensure correctness. + * Some devices need protocol transactions to be built from a series of + * spi_message submissions, where the content of one message is determined + * by the results of previous messages and where the whole transaction + * ends when the chipselect goes intactive. + * + * When SPI can transfer in 1x,2x or 4x. It can get this transfer information + * from device through @tx_nbits and @rx_nbits. In Bi-direction, these + * two should both be set. User can set transfer mode with SPI_NBITS_SINGLE(1x) + * SPI_NBITS_DUAL(2x) and SPI_NBITS_QUAD(4x) to support these three transfer. + * + * The code that submits an spi_message (and its spi_transfers) + * to the lower layers is responsible for managing its memory. + * Zero-initialize every field you don't set up explicitly, to + * insulate against future API updates. After you submit a message + * and its transfers, ignore them until its completion callback. + */ +struct spi_transfer { + /* it's ok if tx_buf == rx_buf (right?) + * for MicroWire, one buffer must be null + * buffers must work with dma_*map_single() calls, unless + * spi_message.is_dma_mapped reports a pre-existing mapping + */ + const void *tx_buf; + void *rx_buf; + unsigned len; + + dma_addr_t tx_dma; + dma_addr_t rx_dma; + struct sg_table tx_sg; + struct sg_table rx_sg; + + unsigned cs_change:1; + unsigned tx_nbits:3; + unsigned rx_nbits:3; +#define SPI_NBITS_SINGLE 0x01 /* 1bit transfer */ +#define SPI_NBITS_DUAL 0x02 /* 2bits transfer */ +#define SPI_NBITS_QUAD 0x04 /* 4bits transfer */ + u8 bits_per_word; + u16 delay_usecs; + u32 speed_hz; + + struct list_head transfer_list; +}; + +/** + * struct spi_message - one multi-segment SPI transaction + * @transfers: list of transfer segments in this transaction + * @spi: SPI device to which the transaction is queued + * @is_dma_mapped: if true, the caller provided both dma and cpu virtual + * addresses for each transfer buffer + * @complete: called to report transaction completions + * @context: the argument to complete() when it's called + * @frame_length: the total number of bytes in the message + * @actual_length: the total number of bytes that were transferred in all + * successful segments + * @status: zero for success, else negative errno + * @queue: for use by whichever driver currently owns the message + * @state: for use by whichever driver currently owns the message + * + * A @spi_message is used to execute an atomic sequence of data transfers, + * each represented by a struct spi_transfer. The sequence is "atomic" + * in the sense that no other spi_message may use that SPI bus until that + * sequence completes. On some systems, many such sequences can execute as + * as single programmed DMA transfer. On all systems, these messages are + * queued, and might complete after transactions to other devices. Messages + * sent to a given spi_device are always executed in FIFO order. + * + * The code that submits an spi_message (and its spi_transfers) + * to the lower layers is responsible for managing its memory. + * Zero-initialize every field you don't set up explicitly, to + * insulate against future API updates. After you submit a message + * and its transfers, ignore them until its completion callback. + */ +struct spi_message { + struct list_head transfers; + + struct spi_device *spi; + + unsigned is_dma_mapped:1; + + /* REVISIT: we might want a flag affecting the behavior of the + * last transfer ... allowing things like "read 16 bit length L" + * immediately followed by "read L bytes". Basically imposing + * a specific message scheduling algorithm. + * + * Some controller drivers (message-at-a-time queue processing) + * could provide that as their default scheduling algorithm. But + * others (with multi-message pipelines) could need a flag to + * tell them about such special cases. + */ + + /* completion is reported through a callback */ + void (*complete)(void *context); + void *context; + unsigned frame_length; + unsigned actual_length; + int status; + + /* for optional use by whatever driver currently owns the + * spi_message ... between calls to spi_async and then later + * complete(), that's the spi_master controller driver. + */ + struct list_head queue; + void *state; +}; + +static inline void spi_message_init(struct spi_message *m) +{ + memset(m, 0, sizeof *m); + INIT_LIST_HEAD(&m->transfers); +} + +static inline void +spi_message_add_tail(struct spi_transfer *t, struct spi_message *m) +{ + list_add_tail(&t->transfer_list, &m->transfers); +} + +static inline void +spi_transfer_del(struct spi_transfer *t) +{ + list_del(&t->transfer_list); +} + +/** + * spi_message_init_with_transfers - Initialize spi_message and append transfers + * @m: spi_message to be initialized + * @xfers: An array of spi transfers + * @num_xfers: Number of items in the xfer array + * + * This function initializes the given spi_message and adds each spi_transfer in + * the given array to the message. + */ +static inline void +spi_message_init_with_transfers(struct spi_message *m, +struct spi_transfer *xfers, unsigned int num_xfers) +{ + unsigned int i; + + spi_message_init(m); + for (i = 0; i < num_xfers; ++i) + spi_message_add_tail(&xfers[i], m); +} + +/* It's fine to embed message and transaction structures in other data + * structures so long as you don't free them while they're in use. + */ + +static inline struct spi_message *spi_message_alloc(unsigned ntrans, gfp_t flags) +{ + struct spi_message *m; + + m = kzalloc(sizeof(struct spi_message) + + ntrans * sizeof(struct spi_transfer), + flags); + if (m) { + unsigned i; + struct spi_transfer *t = (struct spi_transfer *)(m + 1); + + INIT_LIST_HEAD(&m->transfers); + for (i = 0; i < ntrans; i++, t++) + spi_message_add_tail(t, m); + } + return m; +} + +static inline void spi_message_free(struct spi_message *m) +{ + kfree(m); +} + +extern int spi_setup(struct spi_device *spi); +extern int spi_async(struct spi_device *spi, struct spi_message *message); +extern int spi_async_locked(struct spi_device *spi, + struct spi_message *message); + +/*---------------------------------------------------------------------------*/ + +/* All these synchronous SPI transfer routines are utilities layered + * over the core async transfer primitive. Here, "synchronous" means + * they will sleep uninterruptibly until the async transfer completes. + */ + +extern int spi_sync(struct spi_device *spi, struct spi_message *message); +extern int spi_sync_locked(struct spi_device *spi, struct spi_message *message); +extern int spi_bus_lock(struct spi_master *master); +extern int spi_bus_unlock(struct spi_master *master); + +/** + * spi_write - SPI synchronous write + * @spi: device to which data will be written + * @buf: data buffer + * @len: data buffer size + * Context: can sleep + * + * This writes the buffer and returns zero or a negative error code. + * Callable only from contexts that can sleep. + */ +static inline int +spi_write(struct spi_device *spi, const void *buf, size_t len) +{ + struct spi_transfer t = { + .tx_buf = buf, + .len = len, + }; + struct spi_message m; + + spi_message_init(&m); + spi_message_add_tail(&t, &m); + return spi_sync(spi, &m); +} + +/** + * spi_read - SPI synchronous read + * @spi: device from which data will be read + * @buf: data buffer + * @len: data buffer size + * Context: can sleep + * + * This reads the buffer and returns zero or a negative error code. + * Callable only from contexts that can sleep. + */ +static inline int +spi_read(struct spi_device *spi, void *buf, size_t len) +{ + struct spi_transfer t = { + .rx_buf = buf, + .len = len, + }; + struct spi_message m; + + spi_message_init(&m); + spi_message_add_tail(&t, &m); + return spi_sync(spi, &m); +} + +/** + * spi_sync_transfer - synchronous SPI data transfer + * @spi: device with which data will be exchanged + * @xfers: An array of spi_transfers + * @num_xfers: Number of items in the xfer array + * Context: can sleep + * + * Does a synchronous SPI data transfer of the given spi_transfer array. + * + * For more specific semantics see spi_sync(). + * + * It returns zero on success, else a negative error code. + */ +static inline int +spi_sync_transfer(struct spi_device *spi, struct spi_transfer *xfers, + unsigned int num_xfers) +{ + struct spi_message msg; + + spi_message_init_with_transfers(&msg, xfers, num_xfers); + + return spi_sync(spi, &msg); +} + +/* this copies txbuf and rxbuf data; for small transfers only! */ +extern int spi_write_then_read(struct spi_device *spi, + const void *txbuf, unsigned n_tx, + void *rxbuf, unsigned n_rx); + +/** + * spi_w8r8 - SPI synchronous 8 bit write followed by 8 bit read + * @spi: device with which data will be exchanged + * @cmd: command to be written before data is read back + * Context: can sleep + * + * This returns the (unsigned) eight bit number returned by the + * device, or else a negative error code. Callable only from + * contexts that can sleep. + */ +static inline ssize_t spi_w8r8(struct spi_device *spi, u8 cmd) +{ + ssize_t status; + u8 result; + + status = spi_write_then_read(spi, &cmd, 1, &result, 1); + + /* return negative errno or unsigned value */ + return (status < 0) ? status : result; +} + +/** + * spi_w8r16 - SPI synchronous 8 bit write followed by 16 bit read + * @spi: device with which data will be exchanged + * @cmd: command to be written before data is read back + * Context: can sleep + * + * This returns the (unsigned) sixteen bit number returned by the + * device, or else a negative error code. Callable only from + * contexts that can sleep. + * + * The number is returned in wire-order, which is at least sometimes + * big-endian. + */ +static inline ssize_t spi_w8r16(struct spi_device *spi, u8 cmd) +{ + ssize_t status; + u16 result; + + status = spi_write_then_read(spi, &cmd, 1, &result, 2); + + /* return negative errno or unsigned value */ + return (status < 0) ? status : result; +} + +/** + * spi_w8r16be - SPI synchronous 8 bit write followed by 16 bit big-endian read + * @spi: device with which data will be exchanged + * @cmd: command to be written before data is read back + * Context: can sleep + * + * This returns the (unsigned) sixteen bit number returned by the device in cpu + * endianness, or else a negative error code. Callable only from contexts that + * can sleep. + * + * This function is similar to spi_w8r16, with the exception that it will + * convert the read 16 bit data word from big-endian to native endianness. + * + */ +static inline ssize_t spi_w8r16be(struct spi_device *spi, u8 cmd) + +{ + ssize_t status; + __be16 result; + + status = spi_write_then_read(spi, &cmd, 1, &result, 2); + if (status < 0) + return status; + + return be16_to_cpu(result); +} + +/*---------------------------------------------------------------------------*/ + +/* + * INTERFACE between board init code and SPI infrastructure. + * + * No SPI driver ever sees these SPI device table segments, but + * it's how the SPI core (or adapters that get hotplugged) grows + * the driver model tree. + * + * As a rule, SPI devices can't be probed. Instead, board init code + * provides a table listing the devices which are present, with enough + * information to bind and set up the device's driver. There's basic + * support for nonstatic configurations too; enough to handle adding + * parport adapters, or microcontrollers acting as USB-to-SPI bridges. + */ + +/** + * struct spi_board_info - board-specific template for a SPI device + * @modalias: Initializes spi_device.modalias; identifies the driver. + * @platform_data: Initializes spi_device.platform_data; the particular + * data stored there is driver-specific. + * @controller_data: Initializes spi_device.controller_data; some + * controllers need hints about hardware setup, e.g. for DMA. + * @irq: Initializes spi_device.irq; depends on how the board is wired. + * @max_speed_hz: Initializes spi_device.max_speed_hz; based on limits + * from the chip datasheet and board-specific signal quality issues. + * @bus_num: Identifies which spi_master parents the spi_device; unused + * by spi_new_device(), and otherwise depends on board wiring. + * @chip_select: Initializes spi_device.chip_select; depends on how + * the board is wired. + * @mode: Initializes spi_device.mode; based on the chip datasheet, board + * wiring (some devices support both 3WIRE and standard modes), and + * possibly presence of an inverter in the chipselect path. + * + * When adding new SPI devices to the device tree, these structures serve + * as a partial device template. They hold information which can't always + * be determined by drivers. Information that probe() can establish (such + * as the default transfer wordsize) is not included here. + * + * These structures are used in two places. Their primary role is to + * be stored in tables of board-specific device descriptors, which are + * declared early in board initialization and then used (much later) to + * populate a controller's device tree after the that controller's driver + * initializes. A secondary (and atypical) role is as a parameter to + * spi_new_device() call, which happens after those controller drivers + * are active in some dynamic board configuration models. + */ +struct spi_board_info { + /* the device name and module name are coupled, like platform_bus; + * "modalias" is normally the driver name. + * + * platform_data goes to spi_device.dev.platform_data, + * controller_data goes to spi_device.controller_data, + * irq is copied too + */ + char modalias[SPI_NAME_SIZE]; + const void *platform_data; + void *controller_data; + int irq; + + /* slower signaling on noisy or low voltage boards */ + u32 max_speed_hz; + + + /* bus_num is board specific and matches the bus_num of some + * spi_master that will probably be registered later. + * + * chip_select reflects how this chip is wired to that master; + * it's less than num_chipselect. + */ + u16 bus_num; + u16 chip_select; + + /* mode becomes spi_device.mode, and is essential for chips + * where the default of SPI_CS_HIGH = 0 is wrong. + */ + u16 mode; + + /* ... may need additional spi_device chip config data here. + * avoid stuff protocol drivers can set; but include stuff + * needed to behave without being bound to a driver: + * - quirks like clock rate mattering when not selected + */ +}; + +#ifdef CONFIG_SPI +extern int +spi_register_board_info(struct spi_board_info const *info, unsigned n); +#else +/* board init code may ignore whether SPI is configured or not */ +static inline int +spi_register_board_info(struct spi_board_info const *info, unsigned n) + { return 0; } +#endif + + +/* If you're hotplugging an adapter with devices (parport, usb, etc) + * use spi_new_device() to describe each device. You can also call + * spi_unregister_device() to start making that device vanish, but + * normally that would be handled by spi_unregister_master(). + * + * You can also use spi_alloc_device() and spi_add_device() to use a two + * stage registration sequence for each spi_device. This gives the caller + * some more control over the spi_device structure before it is registered, + * but requires that caller to initialize fields that would otherwise + * be defined using the board info. + */ +extern struct spi_device * +spi_alloc_device(struct spi_master *master); + +extern int +spi_add_device(struct spi_device *spi); + +extern struct spi_device * +spi_new_device(struct spi_master *, struct spi_board_info *); + +static inline void +spi_unregister_device(struct spi_device *spi) +{ + if (spi) + device_unregister(&spi->dev); +} + +extern const struct spi_device_id * +spi_get_device_id(const struct spi_device *sdev); + +static inline bool +spi_transfer_is_last(struct spi_master *master, struct spi_transfer *xfer) +{ + return list_is_last(&xfer->transfer_list, &master->cur_msg->transfers); +} + +#endif /* __LINUX_SPI_H */ |