diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/devices.txt | 5 | ||||
| -rw-r--r-- | Documentation/feature-removal-schedule.txt | 9 | ||||
| -rw-r--r-- | Documentation/firmware_class/README | 17 | ||||
| -rw-r--r-- | Documentation/firmware_class/firmware_sample_driver.c | 11 | ||||
| -rw-r--r-- | Documentation/memory-barriers.txt | 4 | ||||
| -rw-r--r-- | Documentation/spi/pxa2xx | 234 | ||||
| -rw-r--r-- | Documentation/spi/spi-summary | 34 | ||||
| -rw-r--r-- | Documentation/watchdog/watchdog-api.txt | 3 |
8 files changed, 281 insertions, 36 deletions
diff --git a/Documentation/devices.txt b/Documentation/devices.txt index 3c406acd4dfa..b369a8c46a73 100644 --- a/Documentation/devices.txt +++ b/Documentation/devices.txt @@ -1721,11 +1721,6 @@ Your cooperation is appreciated. These devices support the same API as the generic SCSI devices. - 97 block Packet writing for CD/DVD devices - 0 = /dev/pktcdvd0 First packet-writing module - 1 = /dev/pktcdvd1 Second packet-writing module - ... - 98 char Control and Measurement Device (comedi) 0 = /dev/comedi0 First comedi device 1 = /dev/comedi1 Second comedi device diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt index 421bcfff6ad2..43ab119963d5 100644 --- a/Documentation/feature-removal-schedule.txt +++ b/Documentation/feature-removal-schedule.txt @@ -57,6 +57,15 @@ Who: Jody McIntyre <scjody@steamballoon.com> --------------------------- +What: sbp2: module parameter "force_inquiry_hack" +When: July 2006 +Why: Superceded by parameter "workarounds". Both parameters are meant to be + used ad-hoc and for single devices only, i.e. not in modprobe.conf, + therefore the impact of this feature replacement should be low. +Who: Stefan Richter <stefanr@s5r6.in-berlin.de> + +--------------------------- + What: Video4Linux API 1 ioctls and video_decoder.h from Video devices. When: July 2006 Why: V4L1 AP1 was replaced by V4L2 API. during migration from 2.4 to 2.6 diff --git a/Documentation/firmware_class/README b/Documentation/firmware_class/README index 43e836c07ae8..e9cc8bb26f7d 100644 --- a/Documentation/firmware_class/README +++ b/Documentation/firmware_class/README @@ -105,20 +105,3 @@ on the setup, so I think that the choice on what firmware to make persistent should be left to userspace. - - Why register_firmware()+__init can be useful: - - For boot devices needing firmware. - - To make the transition easier: - The firmware can be declared __init and register_firmware() - called on module_init. Then the firmware is warranted to be - there even if "firmware hotplug userspace" is not there yet or - it doesn't yet provide the needed firmware. - Once the firmware is widely available in userspace, it can be - removed from the kernel. Or made optional (CONFIG_.*_FIRMWARE). - - In either case, if firmware hotplug support is there, it can move the - firmware out of kernel memory into the real filesystem for later - usage. - - Note: If persistence is implemented on top of initramfs, - register_firmware() may not be appropriate. - diff --git a/Documentation/firmware_class/firmware_sample_driver.c b/Documentation/firmware_class/firmware_sample_driver.c index ad3edaba4533..87feccdb5c9f 100644 --- a/Documentation/firmware_class/firmware_sample_driver.c +++ b/Documentation/firmware_class/firmware_sample_driver.c @@ -5,8 +5,6 @@ * * Sample code on how to use request_firmware() from drivers. * - * Note that register_firmware() is currently useless. - * */ #include <linux/module.h> @@ -17,11 +15,6 @@ #include "linux/firmware.h" -#define WE_CAN_NEED_FIRMWARE_BEFORE_USERSPACE_IS_AVAILABLE -#ifdef WE_CAN_NEED_FIRMWARE_BEFORE_USERSPACE_IS_AVAILABLE -char __init inkernel_firmware[] = "let's say that this is firmware\n"; -#endif - static struct device ghost_device = { .bus_id = "ghost0", }; @@ -104,10 +97,6 @@ static void sample_probe_async(void) static int sample_init(void) { -#ifdef WE_CAN_NEED_FIRMWARE_BEFORE_USERSPACE_IS_AVAILABLE - register_firmware("sample_driver_fw", inkernel_firmware, - sizeof(inkernel_firmware)); -#endif device_initialize(&ghost_device); /* since there is no real hardware insertion I just call the * sample probe functions here */ diff --git a/Documentation/memory-barriers.txt b/Documentation/memory-barriers.txt index 92f0056d928c..c61d8b876fdb 100644 --- a/Documentation/memory-barriers.txt +++ b/Documentation/memory-barriers.txt @@ -1031,7 +1031,7 @@ conflict on any particular lock. LOCKS VS MEMORY ACCESSES ------------------------ -Consider the following: the system has a pair of spinlocks (N) and (Q), and +Consider the following: the system has a pair of spinlocks (M) and (Q), and three CPUs; then should the following sequence of events occur: CPU 1 CPU 2 @@ -1678,7 +1678,7 @@ CPU's caches by some other cache event: smp_wmb(); <A:modify v=2> <C:busy> <C:queue v=2> - p = &b; q = p; + p = &v; q = p; <D:request p> <B:modify p=&v> <D:commit p=&v> <D:read p> diff --git a/Documentation/spi/pxa2xx b/Documentation/spi/pxa2xx new file mode 100644 index 000000000000..9c45f3df2e18 --- /dev/null +++ b/Documentation/spi/pxa2xx @@ -0,0 +1,234 @@ +PXA2xx SPI on SSP driver HOWTO +=================================================== +This a mini howto on the pxa2xx_spi driver. The driver turns a PXA2xx +synchronous serial port into a SPI master controller +(see Documentation/spi/spi_summary). The driver has the following features + +- Support for any PXA2xx SSP +- SSP PIO and SSP DMA data transfers. +- External and Internal (SSPFRM) chip selects. +- Per slave device (chip) configuration. +- Full suspend, freeze, resume support. + +The driver is built around a "spi_message" fifo serviced by workqueue and a +tasklet. The workqueue, "pump_messages", drives message fifo and the tasklet +(pump_transfer) is responsible for queuing SPI transactions and setting up and +launching the dma/interrupt driven transfers. + +Declaring PXA2xx Master Controllers +----------------------------------- +Typically a SPI master is defined in the arch/.../mach-*/board-*.c as a +"platform device". The master configuration is passed to the driver via a table +found in include/asm-arm/arch-pxa/pxa2xx_spi.h: + +struct pxa2xx_spi_master { + enum pxa_ssp_type ssp_type; + u32 clock_enable; + u16 num_chipselect; + u8 enable_dma; +}; + +The "pxa2xx_spi_master.ssp_type" field must have a value between 1 and 3 and +informs the driver which features a particular SSP supports. + +The "pxa2xx_spi_master.clock_enable" field is used to enable/disable the +corresponding SSP peripheral block in the "Clock Enable Register (CKEN"). See +the "PXA2xx Developer Manual" section "Clocks and Power Management". + +The "pxa2xx_spi_master.num_chipselect" field is used to determine the number of +slave device (chips) attached to this SPI master. + +The "pxa2xx_spi_master.enable_dma" field informs the driver that SSP DMA should +be used. This caused the driver to acquire two DMA channels: rx_channel and +tx_channel. The rx_channel has a higher DMA service priority the tx_channel. +See the "PXA2xx Developer Manual" section "DMA Controller". + +NSSP MASTER SAMPLE +------------------ +Below is a sample configuration using the PXA255 NSSP. + +static struct resource pxa_spi_nssp_resources[] = { + [0] = { + .start = __PREG(SSCR0_P(2)), /* Start address of NSSP */ + .end = __PREG(SSCR0_P(2)) + 0x2c, /* Range of registers */ + .flags = IORESOURCE_MEM, + }, + [1] = { + .start = IRQ_NSSP, /* NSSP IRQ */ + .end = IRQ_NSSP, + .flags = IORESOURCE_IRQ, + }, +}; + +static struct pxa2xx_spi_master pxa_nssp_master_info = { + .ssp_type = PXA25x_NSSP, /* Type of SSP */ + .clock_enable = CKEN9_NSSP, /* NSSP Peripheral clock */ + .num_chipselect = 1, /* Matches the number of chips attached to NSSP */ + .enable_dma = 1, /* Enables NSSP DMA */ +}; + +static struct platform_device pxa_spi_nssp = { + .name = "pxa2xx-spi", /* MUST BE THIS VALUE, so device match driver */ + .id = 2, /* Bus number, MUST MATCH SSP number 1..n */ + .resource = pxa_spi_nssp_resources, + .num_resources = ARRAY_SIZE(pxa_spi_nssp_resources), + .dev = { + .platform_data = &pxa_nssp_master_info, /* Passed to driver */ + }, +}; + +static struct platform_device *devices[] __initdata = { + &pxa_spi_nssp, +}; + +static void __init board_init(void) +{ + (void)platform_add_device(devices, ARRAY_SIZE(devices)); +} + +Declaring Slave Devices +----------------------- +Typically each SPI slave (chip) is defined in the arch/.../mach-*/board-*.c +using the "spi_board_info" structure found in "linux/spi/spi.h". See +"Documentation/spi/spi_summary" for additional information. + +Each slave device attached to the PXA must provide slave specific configuration +information via the structure "pxa2xx_spi_chip" found in +"include/asm-arm/arch-pxa/pxa2xx_spi.h". The pxa2xx_spi master controller driver +will uses the configuration whenever the driver communicates with the slave +device. + +struct pxa2xx_spi_chip { + u8 tx_threshold; + u8 rx_threshold; + u8 dma_burst_size; + u32 timeout_microsecs; + u8 enable_loopback; + void (*cs_control)(u32 command); +}; + +The "pxa2xx_spi_chip.tx_threshold" and "pxa2xx_spi_chip.rx_threshold" fields are +used to configure the SSP hardware fifo. These fields are critical to the +performance of pxa2xx_spi driver and misconfiguration will result in rx +fifo overruns (especially in PIO mode transfers). Good default values are + + .tx_threshold = 12, + .rx_threshold = 4, + +The "pxa2xx_spi_chip.dma_burst_size" field is used to configure PXA2xx DMA +engine and is related the "spi_device.bits_per_word" field. Read and understand +the PXA2xx "Developer Manual" sections on the DMA controller and SSP Controllers +to determine the correct value. An SSP configured for byte-wide transfers would +use a value of 8. + +The "pxa2xx_spi_chip.timeout_microsecs" fields is used to efficiently handle +trailing bytes in the SSP receiver fifo. The correct value for this field is +dependent on the SPI bus speed ("spi_board_info.max_speed_hz") and the specific +slave device. Please note the the PXA2xx SSP 1 does not support trailing byte +timeouts and must busy-wait any trailing bytes. + +The "pxa2xx_spi_chip.enable_loopback" field is used to place the SSP porting +into internal loopback mode. In this mode the SSP controller internally +connects the SSPTX pin the the SSPRX pin. This is useful for initial setup +testing. + +The "pxa2xx_spi_chip.cs_control" field is used to point to a board specific +function for asserting/deasserting a slave device chip select. If the field is +NULL, the pxa2xx_spi master controller driver assumes that the SSP port is +configured to use SSPFRM instead. + +NSSP SALVE SAMPLE +----------------- +The pxa2xx_spi_chip structure is passed to the pxa2xx_spi driver in the +"spi_board_info.controller_data" field. Below is a sample configuration using +the PXA255 NSSP. + +/* Chip Select control for the CS8415A SPI slave device */ +static void cs8415a_cs_control(u32 command) +{ + if (command & PXA2XX_CS_ASSERT) + GPCR(2) = GPIO_bit(2); + else + GPSR(2) = GPIO_bit(2); +} + +/* Chip Select control for the CS8405A SPI slave device */ +static void cs8405a_cs_control(u32 command) +{ + if (command & PXA2XX_CS_ASSERT) + GPCR(3) = GPIO_bit(3); + else + GPSR(3) = GPIO_bit(3); +} + +static struct pxa2xx_spi_chip cs8415a_chip_info = { + .tx_threshold = 12, /* SSP hardward FIFO threshold */ + .rx_threshold = 4, /* SSP hardward FIFO threshold */ + .dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */ + .timeout_microsecs = 64, /* Wait at least 64usec to handle trailing */ + .cs_control = cs8415a_cs_control, /* Use external chip select */ +}; + +static struct pxa2xx_spi_chip cs8405a_chip_info = { + .tx_threshold = 12, /* SSP hardward FIFO threshold */ + .rx_threshold = 4, /* SSP hardward FIFO threshold */ + .dma_burst_size = 8, /* Byte wide transfers used so 8 byte bursts */ + .timeout_microsecs = 64, /* Wait at least 64usec to handle trailing */ + .cs_control = cs8405a_cs_control, /* Use external chip select */ +}; + +static struct spi_board_info streetracer_spi_board_info[] __initdata = { + { + .modalias = "cs8415a", /* Name of spi_driver for this device */ + .max_speed_hz = 3686400, /* Run SSP as fast a possbile */ + .bus_num = 2, /* Framework bus number */ + .chip_select = 0, /* Framework chip select */ + .platform_data = NULL; /* No spi_driver specific config */ + .controller_data = &cs8415a_chip_info, /* Master chip config */ + .irq = STREETRACER_APCI_IRQ, /* Slave device interrupt */ + }, + { + .modalias = "cs8405a", /* Name of spi_driver for this device */ + .max_speed_hz = 3686400, /* Run SSP as fast a possbile */ + .bus_num = 2, /* Framework bus number */ + .chip_select = 1, /* Framework chip select */ + .controller_data = &cs8405a_chip_info, /* Master chip config */ + .irq = STREETRACER_APCI_IRQ, /* Slave device interrupt */ + }, +}; + +static void __init streetracer_init(void) +{ + spi_register_board_info(streetracer_spi_board_info, + ARRAY_SIZE(streetracer_spi_board_info)); +} + + +DMA and PIO I/O Support +----------------------- +The pxa2xx_spi driver support both DMA and interrupt driven PIO message +transfers. The driver defaults to PIO mode and DMA transfers must enabled by +setting the "enable_dma" flag in the "pxa2xx_spi_master" structure and and +ensuring that the "pxa2xx_spi_chip.dma_burst_size" field is non-zero. The DMA +mode support both coherent and stream based DMA mappings. + +The following logic is used to determine the type of I/O to be used on +a per "spi_transfer" basis: + +if !enable_dma or dma_burst_size == 0 then + always use PIO transfers + +if spi_message.is_dma_mapped and rx_dma_buf != 0 and tx_dma_buf != 0 then + use coherent DMA mode + +if rx_buf and tx_buf are aligned on 8 byte boundary then + use streaming DMA mode + +otherwise + use PIO transfer + +THANKS TO +--------- + +David Brownell and others for mentoring the development of this driver. + diff --git a/Documentation/spi/spi-summary b/Documentation/spi/spi-summary index a5ffba33a351..068732d32276 100644 --- a/Documentation/spi/spi-summary +++ b/Documentation/spi/spi-summary @@ -414,7 +414,33 @@ to get the driver-private data allocated for that device. The driver will initialize the fields of that spi_master, including the bus number (maybe the same as the platform device ID) and three methods used to interact with the SPI core and SPI protocol drivers. It will -also initialize its own internal state. +also initialize its own internal state. (See below about bus numbering +and those methods.) + +After you initialize the spi_master, then use spi_register_master() to +publish it to the rest of the system. At that time, device nodes for +the controller and any predeclared spi devices will be made available, +and the driver model core will take care of binding them to drivers. + +If you need to remove your SPI controller driver, spi_unregister_master() +will reverse the effect of spi_register_master(). + + +BUS NUMBERING + +Bus numbering is important, since that's how Linux identifies a given +SPI bus (shared SCK, MOSI, MISO). Valid bus numbers start at zero. On +SOC systems, the bus numbers should match the numbers defined by the chip +manufacturer. For example, hardware controller SPI2 would be bus number 2, +and spi_board_info for devices connected to it would use that number. + +If you don't have such hardware-assigned bus number, and for some reason +you can't just assign them, then provide a negative bus number. That will +then be replaced by a dynamically assigned number. You'd then need to treat +this as a non-static configuration (see above). + + +SPI MASTER METHODS master->setup(struct spi_device *spi) This sets up the device clock rate, SPI mode, and word sizes. @@ -431,6 +457,9 @@ also initialize its own internal state. state it dynamically associates with that device. If you do that, be sure to provide the cleanup() method to free that state. + +SPI MESSAGE QUEUE + The bulk of the driver will be managing the I/O queue fed by transfer(). That queue could be purely conceptual. For example, a driver used only @@ -440,6 +469,9 @@ But the queue will probably be very real, using message->queue, PIO, often DMA (especially if the root filesystem is in SPI flash), and execution contexts like IRQ handlers, tasklets, or workqueues (such as keventd). Your driver can be as fancy, or as simple, as you need. +Such a transfer() method would normally just add the message to a +queue, and then start some asynchronous transfer engine (unless it's +already running). THANKS TO diff --git a/Documentation/watchdog/watchdog-api.txt b/Documentation/watchdog/watchdog-api.txt index c5beb548cfc4..21ed51173662 100644 --- a/Documentation/watchdog/watchdog-api.txt +++ b/Documentation/watchdog/watchdog-api.txt @@ -36,6 +36,9 @@ timeout or margin. The simplest way to ping the watchdog is to write some data to the device. So a very simple watchdog daemon would look like this: +#include <stdlib.h> +#include <fcntl.h> + int main(int argc, const char *argv[]) { int fd=open("/dev/watchdog",O_WRONLY); if (fd==-1) { |