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475 lines
15 KiB
475 lines
15 KiB
<?xml version="1.0" encoding="UTF-8"?> |
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<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.1.2//EN" |
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"http://www.oasis-open.org/docbook/xml/4.1.2/docbookx.dtd" []> |
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|
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<book id="LinuxDriversAPI"> |
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<bookinfo> |
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<title>Linux Device Drivers</title> |
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|
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<legalnotice> |
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<para> |
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This documentation is free software; you can redistribute |
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it and/or modify it under the terms of the GNU General Public |
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License as published by the Free Software Foundation; either |
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version 2 of the License, or (at your option) any later |
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version. |
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</para> |
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|
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<para> |
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This program is distributed in the hope that it will be |
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useful, but WITHOUT ANY WARRANTY; without even the implied |
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warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. |
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See the GNU General Public License for more details. |
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</para> |
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|
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<para> |
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You should have received a copy of the GNU General Public |
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License along with this program; if not, write to the Free |
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, |
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MA 02111-1307 USA |
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</para> |
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|
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<para> |
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For more details see the file COPYING in the source |
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distribution of Linux. |
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</para> |
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</legalnotice> |
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</bookinfo> |
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|
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<toc></toc> |
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|
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<chapter id="Basics"> |
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<title>Driver Basics</title> |
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<sect1><title>Driver Entry and Exit points</title> |
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!Iinclude/linux/init.h |
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</sect1> |
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|
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<sect1><title>Atomic and pointer manipulation</title> |
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!Iarch/x86/include/asm/atomic.h |
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</sect1> |
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|
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<sect1><title>Delaying, scheduling, and timer routines</title> |
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!Iinclude/linux/sched.h |
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!Ekernel/sched/core.c |
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!Ikernel/sched/cpupri.c |
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!Ikernel/sched/fair.c |
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!Iinclude/linux/completion.h |
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!Ekernel/time/timer.c |
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</sect1> |
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<sect1><title>Wait queues and Wake events</title> |
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!Iinclude/linux/wait.h |
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!Ekernel/sched/wait.c |
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</sect1> |
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<sect1><title>High-resolution timers</title> |
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!Iinclude/linux/ktime.h |
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!Iinclude/linux/hrtimer.h |
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!Ekernel/time/hrtimer.c |
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</sect1> |
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<sect1><title>Workqueues and Kevents</title> |
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!Ekernel/workqueue.c |
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</sect1> |
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<sect1><title>Internal Functions</title> |
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!Ikernel/exit.c |
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!Ikernel/signal.c |
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!Iinclude/linux/kthread.h |
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!Ekernel/kthread.c |
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</sect1> |
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|
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<sect1><title>Kernel objects manipulation</title> |
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<!-- |
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X!Iinclude/linux/kobject.h |
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--> |
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!Elib/kobject.c |
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</sect1> |
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|
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<sect1><title>Kernel utility functions</title> |
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!Iinclude/linux/kernel.h |
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!Ekernel/printk/printk.c |
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!Ekernel/panic.c |
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!Ekernel/sys.c |
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!Ekernel/rcu/srcu.c |
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!Ekernel/rcu/tree.c |
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!Ekernel/rcu/tree_plugin.h |
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!Ekernel/rcu/update.c |
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</sect1> |
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|
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<sect1><title>Device Resource Management</title> |
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!Edrivers/base/devres.c |
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</sect1> |
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|
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</chapter> |
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|
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<chapter id="devdrivers"> |
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<title>Device drivers infrastructure</title> |
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<sect1><title>The Basic Device Driver-Model Structures </title> |
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!Iinclude/linux/device.h |
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</sect1> |
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<sect1><title>Device Drivers Base</title> |
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!Idrivers/base/init.c |
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!Edrivers/base/driver.c |
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!Edrivers/base/core.c |
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!Edrivers/base/syscore.c |
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!Edrivers/base/class.c |
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!Idrivers/base/node.c |
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!Edrivers/base/firmware_class.c |
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!Edrivers/base/transport_class.c |
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<!-- Cannot be included, because |
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attribute_container_add_class_device_adapter |
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and attribute_container_classdev_to_container |
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exceed allowed 44 characters maximum |
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X!Edrivers/base/attribute_container.c |
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--> |
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!Edrivers/base/dd.c |
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<!-- |
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X!Edrivers/base/interface.c |
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--> |
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!Iinclude/linux/platform_device.h |
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!Edrivers/base/platform.c |
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!Edrivers/base/bus.c |
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</sect1> |
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<sect1><title>Device Drivers DMA Management</title> |
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!Edrivers/dma-buf/dma-buf.c |
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!Edrivers/dma-buf/fence.c |
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!Edrivers/dma-buf/seqno-fence.c |
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!Iinclude/linux/fence.h |
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!Iinclude/linux/seqno-fence.h |
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!Edrivers/dma-buf/reservation.c |
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!Iinclude/linux/reservation.h |
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!Edrivers/base/dma-coherent.c |
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!Edrivers/base/dma-mapping.c |
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</sect1> |
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<sect1><title>Device Drivers Power Management</title> |
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!Edrivers/base/power/main.c |
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</sect1> |
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<sect1><title>Device Drivers ACPI Support</title> |
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<!-- Internal functions only |
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X!Edrivers/acpi/sleep/main.c |
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X!Edrivers/acpi/sleep/wakeup.c |
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X!Edrivers/acpi/motherboard.c |
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X!Edrivers/acpi/bus.c |
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--> |
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!Edrivers/acpi/scan.c |
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!Idrivers/acpi/scan.c |
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<!-- No correct structured comments |
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X!Edrivers/acpi/pci_bind.c |
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--> |
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</sect1> |
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<sect1><title>Device drivers PnP support</title> |
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!Idrivers/pnp/core.c |
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<!-- No correct structured comments |
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X!Edrivers/pnp/system.c |
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--> |
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!Edrivers/pnp/card.c |
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!Idrivers/pnp/driver.c |
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!Edrivers/pnp/manager.c |
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!Edrivers/pnp/support.c |
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</sect1> |
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<sect1><title>Userspace IO devices</title> |
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!Edrivers/uio/uio.c |
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!Iinclude/linux/uio_driver.h |
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</sect1> |
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</chapter> |
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|
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<chapter id="parportdev"> |
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<title>Parallel Port Devices</title> |
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!Iinclude/linux/parport.h |
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!Edrivers/parport/ieee1284.c |
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!Edrivers/parport/share.c |
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!Idrivers/parport/daisy.c |
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</chapter> |
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|
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<chapter id="message_devices"> |
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<title>Message-based devices</title> |
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<sect1><title>Fusion message devices</title> |
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!Edrivers/message/fusion/mptbase.c |
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!Idrivers/message/fusion/mptbase.c |
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!Edrivers/message/fusion/mptscsih.c |
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!Idrivers/message/fusion/mptscsih.c |
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!Idrivers/message/fusion/mptctl.c |
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!Idrivers/message/fusion/mptspi.c |
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!Idrivers/message/fusion/mptfc.c |
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!Idrivers/message/fusion/mptlan.c |
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</sect1> |
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<sect1><title>I2O message devices</title> |
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!Iinclude/linux/i2o.h |
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!Idrivers/message/i2o/core.h |
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!Edrivers/message/i2o/iop.c |
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!Idrivers/message/i2o/iop.c |
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!Idrivers/message/i2o/config-osm.c |
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!Edrivers/message/i2o/exec-osm.c |
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!Idrivers/message/i2o/exec-osm.c |
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!Idrivers/message/i2o/bus-osm.c |
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!Edrivers/message/i2o/device.c |
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!Idrivers/message/i2o/device.c |
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!Idrivers/message/i2o/driver.c |
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!Idrivers/message/i2o/pci.c |
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!Idrivers/message/i2o/i2o_block.c |
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!Idrivers/message/i2o/i2o_scsi.c |
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!Idrivers/message/i2o/i2o_proc.c |
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</sect1> |
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</chapter> |
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|
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<chapter id="snddev"> |
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<title>Sound Devices</title> |
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!Iinclude/sound/core.h |
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!Esound/sound_core.c |
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!Iinclude/sound/pcm.h |
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!Esound/core/pcm.c |
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!Esound/core/device.c |
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!Esound/core/info.c |
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!Esound/core/rawmidi.c |
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!Esound/core/sound.c |
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!Esound/core/memory.c |
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!Esound/core/pcm_memory.c |
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!Esound/core/init.c |
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!Esound/core/isadma.c |
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!Esound/core/control.c |
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!Esound/core/pcm_lib.c |
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!Esound/core/hwdep.c |
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!Esound/core/pcm_native.c |
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!Esound/core/memalloc.c |
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<!-- FIXME: Removed for now since no structured comments in source |
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X!Isound/sound_firmware.c |
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--> |
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</chapter> |
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|
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<chapter id="uart16x50"> |
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<title>16x50 UART Driver</title> |
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!Edrivers/tty/serial/serial_core.c |
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!Edrivers/tty/serial/8250/8250_core.c |
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</chapter> |
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|
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<chapter id="fbdev"> |
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<title>Frame Buffer Library</title> |
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|
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<para> |
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The frame buffer drivers depend heavily on four data structures. |
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These structures are declared in include/linux/fb.h. They are |
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fb_info, fb_var_screeninfo, fb_fix_screeninfo and fb_monospecs. |
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The last three can be made available to and from userland. |
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</para> |
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<para> |
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fb_info defines the current state of a particular video card. |
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Inside fb_info, there exists a fb_ops structure which is a |
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collection of needed functions to make fbdev and fbcon work. |
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fb_info is only visible to the kernel. |
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</para> |
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<para> |
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fb_var_screeninfo is used to describe the features of a video card |
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that are user defined. With fb_var_screeninfo, things such as |
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depth and the resolution may be defined. |
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</para> |
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<para> |
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The next structure is fb_fix_screeninfo. This defines the |
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properties of a card that are created when a mode is set and can't |
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be changed otherwise. A good example of this is the start of the |
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frame buffer memory. This "locks" the address of the frame buffer |
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memory, so that it cannot be changed or moved. |
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</para> |
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<para> |
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The last structure is fb_monospecs. In the old API, there was |
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little importance for fb_monospecs. This allowed for forbidden things |
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such as setting a mode of 800x600 on a fix frequency monitor. With |
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the new API, fb_monospecs prevents such things, and if used |
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correctly, can prevent a monitor from being cooked. fb_monospecs |
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will not be useful until kernels 2.5.x. |
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</para> |
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|
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<sect1><title>Frame Buffer Memory</title> |
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!Edrivers/video/fbdev/core/fbmem.c |
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</sect1> |
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<!-- |
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<sect1><title>Frame Buffer Console</title> |
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X!Edrivers/video/console/fbcon.c |
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</sect1> |
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--> |
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<sect1><title>Frame Buffer Colormap</title> |
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!Edrivers/video/fbdev/core/fbcmap.c |
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</sect1> |
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<!-- FIXME: |
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drivers/video/fbgen.c has no docs, which stuffs up the sgml. Comment |
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out until somebody adds docs. KAO |
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<sect1><title>Frame Buffer Generic Functions</title> |
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X!Idrivers/video/fbgen.c |
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</sect1> |
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KAO --> |
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<sect1><title>Frame Buffer Video Mode Database</title> |
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!Idrivers/video/fbdev/core/modedb.c |
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!Edrivers/video/fbdev/core/modedb.c |
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</sect1> |
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<sect1><title>Frame Buffer Macintosh Video Mode Database</title> |
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!Edrivers/video/fbdev/macmodes.c |
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</sect1> |
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<sect1><title>Frame Buffer Fonts</title> |
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<para> |
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Refer to the file lib/fonts/fonts.c for more information. |
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</para> |
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<!-- FIXME: Removed for now since no structured comments in source |
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X!Ilib/fonts/fonts.c |
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--> |
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</sect1> |
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</chapter> |
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<chapter id="input_subsystem"> |
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<title>Input Subsystem</title> |
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<sect1><title>Input core</title> |
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!Iinclude/linux/input.h |
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!Edrivers/input/input.c |
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!Edrivers/input/ff-core.c |
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!Edrivers/input/ff-memless.c |
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</sect1> |
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<sect1><title>Multitouch Library</title> |
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!Iinclude/linux/input/mt.h |
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!Edrivers/input/input-mt.c |
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</sect1> |
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<sect1><title>Polled input devices</title> |
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!Iinclude/linux/input-polldev.h |
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!Edrivers/input/input-polldev.c |
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</sect1> |
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<sect1><title>Matrix keyboars/keypads</title> |
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!Iinclude/linux/input/matrix_keypad.h |
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</sect1> |
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<sect1><title>Sparse keymap support</title> |
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!Iinclude/linux/input/sparse-keymap.h |
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!Edrivers/input/sparse-keymap.c |
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</sect1> |
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</chapter> |
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<chapter id="spi"> |
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<title>Serial Peripheral Interface (SPI)</title> |
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<para> |
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SPI is the "Serial Peripheral Interface", widely used with |
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embedded systems because it is a simple and efficient |
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interface: basically a multiplexed shift register. |
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Its three signal wires hold a clock (SCK, often in the range |
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of 1-20 MHz), a "Master Out, Slave In" (MOSI) data line, and |
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a "Master In, Slave Out" (MISO) data line. |
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SPI is a full duplex protocol; for each bit shifted out the |
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MOSI line (one per clock) another is shifted in on the MISO line. |
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Those bits are assembled into words of various sizes on the |
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way to and from system memory. |
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An additional chipselect line is usually active-low (nCS); |
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four signals are normally used for each peripheral, plus |
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sometimes an interrupt. |
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</para> |
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<para> |
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The SPI bus facilities listed here provide a generalized |
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interface to declare SPI busses and devices, manage them |
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according to the standard Linux driver model, and perform |
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input/output operations. |
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At this time, only "master" side interfaces are supported, |
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where Linux talks to SPI peripherals and does not implement |
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such a peripheral itself. |
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(Interfaces to support implementing SPI slaves would |
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necessarily look different.) |
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</para> |
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<para> |
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The programming interface is structured around two kinds of driver, |
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and two kinds of device. |
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A "Controller Driver" abstracts the controller hardware, which may |
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be as simple as a set of GPIO pins or as complex as a pair of FIFOs |
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connected to dual DMA engines on the other side of the SPI shift |
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register (maximizing throughput). Such drivers bridge between |
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whatever bus they sit on (often the platform bus) and SPI, and |
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expose the SPI side of their device as a |
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<structname>struct spi_master</structname>. |
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SPI devices are children of that master, represented as a |
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<structname>struct spi_device</structname> and manufactured from |
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<structname>struct spi_board_info</structname> descriptors which |
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are usually provided by board-specific initialization code. |
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A <structname>struct spi_driver</structname> is called a |
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"Protocol Driver", and is bound to a spi_device using normal |
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driver model calls. |
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</para> |
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<para> |
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The I/O model is a set of queued messages. Protocol drivers |
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submit one or more <structname>struct spi_message</structname> |
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objects, which are processed and completed asynchronously. |
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(There are synchronous wrappers, however.) Messages are |
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built from one or more <structname>struct spi_transfer</structname> |
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objects, each of which wraps a full duplex SPI transfer. |
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A variety of protocol tweaking options are needed, because |
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different chips adopt very different policies for how they |
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use the bits transferred with SPI. |
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</para> |
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!Iinclude/linux/spi/spi.h |
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!Fdrivers/spi/spi.c spi_register_board_info |
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!Edrivers/spi/spi.c |
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</chapter> |
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<chapter id="i2c"> |
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<title>I<superscript>2</superscript>C and SMBus Subsystem</title> |
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|
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<para> |
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I<superscript>2</superscript>C (or without fancy typography, "I2C") |
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is an acronym for the "Inter-IC" bus, a simple bus protocol which is |
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widely used where low data rate communications suffice. |
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Since it's also a licensed trademark, some vendors use another |
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name (such as "Two-Wire Interface", TWI) for the same bus. |
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I2C only needs two signals (SCL for clock, SDA for data), conserving |
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board real estate and minimizing signal quality issues. |
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Most I2C devices use seven bit addresses, and bus speeds of up |
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to 400 kHz; there's a high speed extension (3.4 MHz) that's not yet |
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found wide use. |
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I2C is a multi-master bus; open drain signaling is used to |
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arbitrate between masters, as well as to handshake and to |
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synchronize clocks from slower clients. |
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</para> |
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|
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<para> |
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The Linux I2C programming interfaces support only the master |
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side of bus interactions, not the slave side. |
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The programming interface is structured around two kinds of driver, |
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and two kinds of device. |
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An I2C "Adapter Driver" abstracts the controller hardware; it binds |
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to a physical device (perhaps a PCI device or platform_device) and |
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exposes a <structname>struct i2c_adapter</structname> representing |
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each I2C bus segment it manages. |
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On each I2C bus segment will be I2C devices represented by a |
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<structname>struct i2c_client</structname>. Those devices will |
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be bound to a <structname>struct i2c_driver</structname>, |
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which should follow the standard Linux driver model. |
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(At this writing, a legacy model is more widely used.) |
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There are functions to perform various I2C protocol operations; at |
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this writing all such functions are usable only from task context. |
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</para> |
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|
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<para> |
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The System Management Bus (SMBus) is a sibling protocol. Most SMBus |
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systems are also I2C conformant. The electrical constraints are |
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tighter for SMBus, and it standardizes particular protocol messages |
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and idioms. Controllers that support I2C can also support most |
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SMBus operations, but SMBus controllers don't support all the protocol |
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options that an I2C controller will. |
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There are functions to perform various SMBus protocol operations, |
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either using I2C primitives or by issuing SMBus commands to |
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i2c_adapter devices which don't support those I2C operations. |
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</para> |
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|
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!Iinclude/linux/i2c.h |
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!Fdrivers/i2c/i2c-boardinfo.c i2c_register_board_info |
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!Edrivers/i2c/i2c-core.c |
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</chapter> |
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|
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<chapter id="hsi"> |
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<title>High Speed Synchronous Serial Interface (HSI)</title> |
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|
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<para> |
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High Speed Synchronous Serial Interface (HSI) is a |
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serial interface mainly used for connecting application |
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engines (APE) with cellular modem engines (CMT) in cellular |
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handsets. |
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|
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HSI provides multiplexing for up to 16 logical channels, |
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low-latency and full duplex communication. |
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</para> |
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|
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!Iinclude/linux/hsi/hsi.h |
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!Edrivers/hsi/hsi.c |
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</chapter> |
|
|
|
</book>
|
|
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