c73bbaa4ec
The mutex lock at rc_register_device() was added by commit 08aeb7c9a4
("[media] rc: add locking to fix register/show race").
It is meant to avoid race issues when trying to open a sysfs file while
the RC register didn't complete.
Adding a lock there causes troubles, as detected by the Kernel lock
debug instrumentation at the Kernel:
======================================================
[ INFO: possible circular locking dependency detected ]
4.5.0-rc3+ #46 Not tainted
-------------------------------------------------------
systemd-udevd/2681 is trying to acquire lock:
(s_active#171){++++.+}, at: [<ffffffff8171a115>] kernfs_remove_by_name_ns+0x45/0xa0
but task is already holding lock:
(&dev->lock){+.+.+.}, at: [<ffffffffa0724def>] rc_register_device+0xb2f/0x1450 [rc_core]
which lock already depends on the new lock.
the existing dependency chain (in reverse order) is:
-> #1 (&dev->lock){+.+.+.}:
[<ffffffff8124817d>] lock_acquire+0x13d/0x320
[<ffffffff822de966>] mutex_lock_nested+0xb6/0x860
[<ffffffffa0721f2b>] show_protocols+0x3b/0x3f0 [rc_core]
[<ffffffff81cdaba5>] dev_attr_show+0x45/0xc0
[<ffffffff8171f1b3>] sysfs_kf_seq_show+0x203/0x3c0
[<ffffffff8171a6a1>] kernfs_seq_show+0x121/0x1b0
[<ffffffff81617c71>] seq_read+0x2f1/0x1160
[<ffffffff8171c911>] kernfs_fop_read+0x321/0x460
[<ffffffff815abc20>] __vfs_read+0xe0/0x3d0
[<ffffffff815ae90e>] vfs_read+0xde/0x2d0
[<ffffffff815b1d01>] SyS_read+0x111/0x230
[<ffffffff822e8636>] entry_SYSCALL_64_fastpath+0x16/0x76
-> #0 (s_active#171){++++.+}:
[<ffffffff81244f24>] __lock_acquire+0x4304/0x5990
[<ffffffff8124817d>] lock_acquire+0x13d/0x320
[<ffffffff81717d3a>] __kernfs_remove+0x58a/0x810
[<ffffffff8171a115>] kernfs_remove_by_name_ns+0x45/0xa0
[<ffffffff81721592>] remove_files.isra.0+0x72/0x190
[<ffffffff8172174b>] sysfs_remove_group+0x9b/0x150
[<ffffffff81721854>] sysfs_remove_groups+0x54/0xa0
[<ffffffff81cd97d0>] device_remove_attrs+0xb0/0x140
[<ffffffff81cdb27c>] device_del+0x38c/0x6b0
[<ffffffffa0724b8b>] rc_register_device+0x8cb/0x1450 [rc_core]
[<ffffffffa1326a7b>] dvb_usb_remote_init+0x66b/0x14d0 [dvb_usb]
[<ffffffffa1321c81>] dvb_usb_device_init+0xf21/0x1860 [dvb_usb]
[<ffffffffa13517dc>] dib0700_probe+0x14c/0x410 [dvb_usb_dib0700]
[<ffffffff81dbb1dd>] usb_probe_interface+0x45d/0x940
[<ffffffff81ce7e7a>] driver_probe_device+0x21a/0xc30
[<ffffffff81ce89b1>] __driver_attach+0x121/0x160
[<ffffffff81ce21bf>] bus_for_each_dev+0x11f/0x1a0
[<ffffffff81ce6cdd>] driver_attach+0x3d/0x50
[<ffffffff81ce5df9>] bus_add_driver+0x4c9/0x770
[<ffffffff81cea39c>] driver_register+0x18c/0x3b0
[<ffffffff81db6e98>] usb_register_driver+0x1f8/0x440
[<ffffffffa074001e>] dib0700_driver_init+0x1e/0x1000 [dvb_usb_dib0700]
[<ffffffff810021b1>] do_one_initcall+0x141/0x300
[<ffffffff8144d8eb>] do_init_module+0x1d0/0x5ad
[<ffffffff812f27b6>] load_module+0x6666/0x9ba0
[<ffffffff812f5fe8>] SyS_finit_module+0x108/0x130
[<ffffffff822e8636>] entry_SYSCALL_64_fastpath+0x16/0x76
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&dev->lock);
lock(s_active#171);
lock(&dev->lock);
lock(s_active#171);
*** DEADLOCK ***
3 locks held by systemd-udevd/2681:
#0: (&dev->mutex){......}, at: [<ffffffff81ce8933>] __driver_attach+0xa3/0x160
#1: (&dev->mutex){......}, at: [<ffffffff81ce8941>] __driver_attach+0xb1/0x160
#2: (&dev->lock){+.+.+.}, at: [<ffffffffa0724def>] rc_register_device+0xb2f/0x1450 [rc_core]
In this specific case, some error happened during device init,
causing IR to be disabled.
Let's fix it by adding a var that will tell when the device is
initialized. Any calls before that will return a -EINVAL.
That should prevent the race issues.
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
284 lines
9.3 KiB
C
284 lines
9.3 KiB
C
/*
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* Remote Controller core header
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*
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* Copyright (C) 2009-2010 by Mauro Carvalho Chehab
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation version 2 of the License.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef _RC_CORE
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#define _RC_CORE
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#include <linux/spinlock.h>
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#include <linux/kfifo.h>
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#include <linux/time.h>
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#include <linux/timer.h>
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#include <media/rc-map.h>
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extern int rc_core_debug;
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#define IR_dprintk(level, fmt, ...) \
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do { \
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if (rc_core_debug >= level) \
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printk(KERN_DEBUG pr_fmt(fmt), ##__VA_ARGS__); \
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} while (0)
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enum rc_driver_type {
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RC_DRIVER_SCANCODE = 0, /* Driver or hardware generates a scancode */
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RC_DRIVER_IR_RAW, /* Needs a Infra-Red pulse/space decoder */
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};
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/**
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* struct rc_scancode_filter - Filter scan codes.
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* @data: Scancode data to match.
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* @mask: Mask of bits of scancode to compare.
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*/
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struct rc_scancode_filter {
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u32 data;
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u32 mask;
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};
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/**
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* enum rc_filter_type - Filter type constants.
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* @RC_FILTER_NORMAL: Filter for normal operation.
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* @RC_FILTER_WAKEUP: Filter for waking from suspend.
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* @RC_FILTER_MAX: Number of filter types.
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*/
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enum rc_filter_type {
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RC_FILTER_NORMAL = 0,
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RC_FILTER_WAKEUP,
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RC_FILTER_MAX
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};
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/**
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* struct rc_dev - represents a remote control device
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* @dev: driver model's view of this device
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* @initialized: true if the device init has completed
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* @sysfs_groups: sysfs attribute groups
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* @input_name: name of the input child device
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* @input_phys: physical path to the input child device
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* @input_id: id of the input child device (struct input_id)
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* @driver_name: name of the hardware driver which registered this device
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* @map_name: name of the default keymap
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* @rc_map: current scan/key table
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* @lock: used to ensure we've filled in all protocol details before
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* anyone can call show_protocols or store_protocols
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* @minor: unique minor remote control device number
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* @raw: additional data for raw pulse/space devices
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* @input_dev: the input child device used to communicate events to userspace
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* @driver_type: specifies if protocol decoding is done in hardware or software
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* @idle: used to keep track of RX state
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* @allowed_protocols: bitmask with the supported RC_BIT_* protocols
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* @enabled_protocols: bitmask with the enabled RC_BIT_* protocols
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* @allowed_wakeup_protocols: bitmask with the supported RC_BIT_* wakeup protocols
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* @enabled_wakeup_protocols: bitmask with the enabled RC_BIT_* wakeup protocols
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* @scancode_filter: scancode filter
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* @scancode_wakeup_filter: scancode wakeup filters
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* @scancode_mask: some hardware decoders are not capable of providing the full
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* scancode to the application. As this is a hardware limit, we can't do
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* anything with it. Yet, as the same keycode table can be used with other
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* devices, a mask is provided to allow its usage. Drivers should generally
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* leave this field in blank
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* @users: number of current users of the device
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* @priv: driver-specific data
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* @keylock: protects the remaining members of the struct
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* @keypressed: whether a key is currently pressed
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* @keyup_jiffies: time (in jiffies) when the current keypress should be released
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* @timer_keyup: timer for releasing a keypress
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* @last_keycode: keycode of last keypress
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* @last_protocol: protocol of last keypress
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* @last_scancode: scancode of last keypress
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* @last_toggle: toggle value of last command
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* @timeout: optional time after which device stops sending data
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* @min_timeout: minimum timeout supported by device
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* @max_timeout: maximum timeout supported by device
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* @rx_resolution : resolution (in ns) of input sampler
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* @tx_resolution: resolution (in ns) of output sampler
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* @change_protocol: allow changing the protocol used on hardware decoders
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* @change_wakeup_protocol: allow changing the protocol used for wakeup
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* filtering
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* @open: callback to allow drivers to enable polling/irq when IR input device
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* is opened.
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* @close: callback to allow drivers to disable polling/irq when IR input device
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* is opened.
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* @s_tx_mask: set transmitter mask (for devices with multiple tx outputs)
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* @s_tx_carrier: set transmit carrier frequency
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* @s_tx_duty_cycle: set transmit duty cycle (0% - 100%)
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* @s_rx_carrier_range: inform driver about carrier it is expected to handle
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* @tx_ir: transmit IR
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* @s_idle: enable/disable hardware idle mode, upon which,
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* device doesn't interrupt host until it sees IR pulses
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* @s_learning_mode: enable wide band receiver used for learning
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* @s_carrier_report: enable carrier reports
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* @s_filter: set the scancode filter
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* @s_wakeup_filter: set the wakeup scancode filter
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*/
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struct rc_dev {
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struct device dev;
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bool initialized;
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const struct attribute_group *sysfs_groups[5];
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const char *input_name;
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const char *input_phys;
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struct input_id input_id;
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char *driver_name;
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const char *map_name;
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struct rc_map rc_map;
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struct mutex lock;
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unsigned int minor;
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struct ir_raw_event_ctrl *raw;
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struct input_dev *input_dev;
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enum rc_driver_type driver_type;
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bool idle;
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u64 allowed_protocols;
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u64 enabled_protocols;
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u64 allowed_wakeup_protocols;
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u64 enabled_wakeup_protocols;
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struct rc_scancode_filter scancode_filter;
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struct rc_scancode_filter scancode_wakeup_filter;
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u32 scancode_mask;
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u32 users;
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void *priv;
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spinlock_t keylock;
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bool keypressed;
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unsigned long keyup_jiffies;
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struct timer_list timer_keyup;
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u32 last_keycode;
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enum rc_type last_protocol;
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u32 last_scancode;
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u8 last_toggle;
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u32 timeout;
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u32 min_timeout;
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u32 max_timeout;
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u32 rx_resolution;
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u32 tx_resolution;
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int (*change_protocol)(struct rc_dev *dev, u64 *rc_type);
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int (*change_wakeup_protocol)(struct rc_dev *dev, u64 *rc_type);
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int (*open)(struct rc_dev *dev);
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void (*close)(struct rc_dev *dev);
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int (*s_tx_mask)(struct rc_dev *dev, u32 mask);
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int (*s_tx_carrier)(struct rc_dev *dev, u32 carrier);
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int (*s_tx_duty_cycle)(struct rc_dev *dev, u32 duty_cycle);
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int (*s_rx_carrier_range)(struct rc_dev *dev, u32 min, u32 max);
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int (*tx_ir)(struct rc_dev *dev, unsigned *txbuf, unsigned n);
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void (*s_idle)(struct rc_dev *dev, bool enable);
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int (*s_learning_mode)(struct rc_dev *dev, int enable);
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int (*s_carrier_report) (struct rc_dev *dev, int enable);
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int (*s_filter)(struct rc_dev *dev,
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struct rc_scancode_filter *filter);
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int (*s_wakeup_filter)(struct rc_dev *dev,
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struct rc_scancode_filter *filter);
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};
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#define to_rc_dev(d) container_of(d, struct rc_dev, dev)
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/*
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* From rc-main.c
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* Those functions can be used on any type of Remote Controller. They
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* basically creates an input_dev and properly reports the device as a
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* Remote Controller, at sys/class/rc.
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*/
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struct rc_dev *rc_allocate_device(void);
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void rc_free_device(struct rc_dev *dev);
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int rc_register_device(struct rc_dev *dev);
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void rc_unregister_device(struct rc_dev *dev);
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int rc_open(struct rc_dev *rdev);
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void rc_close(struct rc_dev *rdev);
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void rc_repeat(struct rc_dev *dev);
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void rc_keydown(struct rc_dev *dev, enum rc_type protocol, u32 scancode, u8 toggle);
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void rc_keydown_notimeout(struct rc_dev *dev, enum rc_type protocol, u32 scancode, u8 toggle);
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void rc_keyup(struct rc_dev *dev);
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u32 rc_g_keycode_from_table(struct rc_dev *dev, u32 scancode);
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/*
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* From rc-raw.c
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* The Raw interface is specific to InfraRed. It may be a good idea to
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* split it later into a separate header.
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*/
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enum raw_event_type {
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IR_SPACE = (1 << 0),
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IR_PULSE = (1 << 1),
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IR_START_EVENT = (1 << 2),
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IR_STOP_EVENT = (1 << 3),
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};
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struct ir_raw_event {
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union {
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u32 duration;
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struct {
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u32 carrier;
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u8 duty_cycle;
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};
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};
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unsigned pulse:1;
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unsigned reset:1;
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unsigned timeout:1;
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unsigned carrier_report:1;
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};
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#define DEFINE_IR_RAW_EVENT(event) \
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struct ir_raw_event event = { \
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{ .duration = 0 } , \
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.pulse = 0, \
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.reset = 0, \
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.timeout = 0, \
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.carrier_report = 0 }
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static inline void init_ir_raw_event(struct ir_raw_event *ev)
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{
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memset(ev, 0, sizeof(*ev));
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}
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#define IR_DEFAULT_TIMEOUT MS_TO_NS(125)
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#define IR_MAX_DURATION 500000000 /* 500 ms */
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#define US_TO_NS(usec) ((usec) * 1000)
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#define MS_TO_US(msec) ((msec) * 1000)
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#define MS_TO_NS(msec) ((msec) * 1000 * 1000)
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void ir_raw_event_handle(struct rc_dev *dev);
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int ir_raw_event_store(struct rc_dev *dev, struct ir_raw_event *ev);
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int ir_raw_event_store_edge(struct rc_dev *dev, enum raw_event_type type);
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int ir_raw_event_store_with_filter(struct rc_dev *dev,
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struct ir_raw_event *ev);
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void ir_raw_event_set_idle(struct rc_dev *dev, bool idle);
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static inline void ir_raw_event_reset(struct rc_dev *dev)
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{
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DEFINE_IR_RAW_EVENT(ev);
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ev.reset = true;
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ir_raw_event_store(dev, &ev);
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ir_raw_event_handle(dev);
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}
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/* extract mask bits out of data and pack them into the result */
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static inline u32 ir_extract_bits(u32 data, u32 mask)
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{
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u32 vbit = 1, value = 0;
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do {
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if (mask & 1) {
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if (data & 1)
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value |= vbit;
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vbit <<= 1;
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}
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data >>= 1;
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} while (mask >>= 1);
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return value;
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}
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#endif /* _RC_CORE */
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