![Phong Hoang](/assets/img/avatar_default.png)
This patch fixes deadlock warning if removing PWM device when CONFIG_PROVE_LOCKING is enabled. This issue can be reproceduced by the following steps on the R-Car H3 Salvator-X board if the backlight is disabled: # cd /sys/class/pwm/pwmchip0 # echo 0 > export # ls device export npwm power pwm0 subsystem uevent unexport # cd device/driver # ls bind e6e31000.pwm uevent unbind # echo e6e31000.pwm > unbind [ 87.659974] ====================================================== [ 87.666149] WARNING: possible circular locking dependency detected [ 87.672327] 5.0.0 #7 Not tainted [ 87.675549] ------------------------------------------------------ [ 87.681723] bash/2986 is trying to acquire lock: [ 87.686337] 000000005ea0e178 (kn->count#58){++++}, at: kernfs_remove_by_name_ns+0x50/0xa0 [ 87.694528] [ 87.694528] but task is already holding lock: [ 87.700353] 000000006313b17c (pwm_lock){+.+.}, at: pwmchip_remove+0x28/0x13c [ 87.707405] [ 87.707405] which lock already depends on the new lock. [ 87.707405] [ 87.715574] [ 87.715574] the existing dependency chain (in reverse order) is: [ 87.723048] [ 87.723048] -> #1 (pwm_lock){+.+.}: [ 87.728017] __mutex_lock+0x70/0x7e4 [ 87.732108] mutex_lock_nested+0x1c/0x24 [ 87.736547] pwm_request_from_chip.part.6+0x34/0x74 [ 87.741940] pwm_request_from_chip+0x20/0x40 [ 87.746725] export_store+0x6c/0x1f4 [ 87.750820] dev_attr_store+0x18/0x28 [ 87.754998] sysfs_kf_write+0x54/0x64 [ 87.759175] kernfs_fop_write+0xe4/0x1e8 [ 87.763615] __vfs_write+0x40/0x184 [ 87.767619] vfs_write+0xa8/0x19c [ 87.771448] ksys_write+0x58/0xbc [ 87.775278] __arm64_sys_write+0x18/0x20 [ 87.779721] el0_svc_common+0xd0/0x124 [ 87.783986] el0_svc_compat_handler+0x1c/0x24 [ 87.788858] el0_svc_compat+0x8/0x18 [ 87.792947] [ 87.792947] -> #0 (kn->count#58){++++}: [ 87.798260] lock_acquire+0xc4/0x22c [ 87.802353] __kernfs_remove+0x258/0x2c4 [ 87.806790] kernfs_remove_by_name_ns+0x50/0xa0 [ 87.811836] remove_files.isra.1+0x38/0x78 [ 87.816447] sysfs_remove_group+0x48/0x98 [ 87.820971] sysfs_remove_groups+0x34/0x4c [ 87.825583] device_remove_attrs+0x6c/0x7c [ 87.830197] device_del+0x11c/0x33c [ 87.834201] device_unregister+0x14/0x2c [ 87.838638] pwmchip_sysfs_unexport+0x40/0x4c [ 87.843509] pwmchip_remove+0xf4/0x13c [ 87.847773] rcar_pwm_remove+0x28/0x34 [ 87.852039] platform_drv_remove+0x24/0x64 [ 87.856651] device_release_driver_internal+0x18c/0x21c [ 87.862391] device_release_driver+0x14/0x1c [ 87.867175] unbind_store+0xe0/0x124 [ 87.871265] drv_attr_store+0x20/0x30 [ 87.875442] sysfs_kf_write+0x54/0x64 [ 87.879618] kernfs_fop_write+0xe4/0x1e8 [ 87.884055] __vfs_write+0x40/0x184 [ 87.888057] vfs_write+0xa8/0x19c [ 87.891887] ksys_write+0x58/0xbc [ 87.895716] __arm64_sys_write+0x18/0x20 [ 87.900154] el0_svc_common+0xd0/0x124 [ 87.904417] el0_svc_compat_handler+0x1c/0x24 [ 87.909289] el0_svc_compat+0x8/0x18 [ 87.913378] [ 87.913378] other info that might help us debug this: [ 87.913378] [ 87.921374] Possible unsafe locking scenario: [ 87.921374] [ 87.927286] CPU0 CPU1 [ 87.931808] ---- ---- [ 87.936331] lock(pwm_lock); [ 87.939293] lock(kn->count#58); [ 87.945120] lock(pwm_lock); [ 87.950599] lock(kn->count#58); [ 87.953908] [ 87.953908] *** DEADLOCK *** [ 87.953908] [ 87.959821] 4 locks held by bash/2986: [ 87.963563] #0: 00000000ace7bc30 (sb_writers#6){.+.+}, at: vfs_write+0x188/0x19c [ 87.971044] #1: 00000000287991b2 (&of->mutex){+.+.}, at: kernfs_fop_write+0xb4/0x1e8 [ 87.978872] #2: 00000000f739d016 (&dev->mutex){....}, at: device_release_driver_internal+0x40/0x21c [ 87.988001] #3: 000000006313b17c (pwm_lock){+.+.}, at: pwmchip_remove+0x28/0x13c [ 87.995481] [ 87.995481] stack backtrace: [ 87.999836] CPU: 0 PID: 2986 Comm: bash Not tainted 5.0.0 #7 [ 88.005489] Hardware name: Renesas Salvator-X board based on r8a7795 ES1.x (DT) [ 88.012791] Call trace: [ 88.015235] dump_backtrace+0x0/0x190 [ 88.018891] show_stack+0x14/0x1c [ 88.022204] dump_stack+0xb0/0xec [ 88.025514] print_circular_bug.isra.32+0x1d0/0x2e0 [ 88.030385] __lock_acquire+0x1318/0x1864 [ 88.034388] lock_acquire+0xc4/0x22c [ 88.037958] __kernfs_remove+0x258/0x2c4 [ 88.041874] kernfs_remove_by_name_ns+0x50/0xa0 [ 88.046398] remove_files.isra.1+0x38/0x78 [ 88.050487] sysfs_remove_group+0x48/0x98 [ 88.054490] sysfs_remove_groups+0x34/0x4c [ 88.058580] device_remove_attrs+0x6c/0x7c [ 88.062671] device_del+0x11c/0x33c [ 88.066154] device_unregister+0x14/0x2c [ 88.070070] pwmchip_sysfs_unexport+0x40/0x4c [ 88.074421] pwmchip_remove+0xf4/0x13c [ 88.078163] rcar_pwm_remove+0x28/0x34 [ 88.081906] platform_drv_remove+0x24/0x64 [ 88.085996] device_release_driver_internal+0x18c/0x21c [ 88.091215] device_release_driver+0x14/0x1c [ 88.095478] unbind_store+0xe0/0x124 [ 88.099048] drv_attr_store+0x20/0x30 [ 88.102704] sysfs_kf_write+0x54/0x64 [ 88.106359] kernfs_fop_write+0xe4/0x1e8 [ 88.110275] __vfs_write+0x40/0x184 [ 88.113757] vfs_write+0xa8/0x19c [ 88.117065] ksys_write+0x58/0xbc [ 88.120374] __arm64_sys_write+0x18/0x20 [ 88.124291] el0_svc_common+0xd0/0x124 [ 88.128034] el0_svc_compat_handler+0x1c/0x24 [ 88.132384] el0_svc_compat+0x8/0x18 The sysfs unexport in pwmchip_remove() is completely asymmetric to what we do in pwmchip_add_with_polarity() and commit0733424c9b
("pwm: Unexport children before chip removal") is a strong indication that this was wrong to begin with. We should just move pwmchip_sysfs_unexport() where it belongs, which is right after pwmchip_sysfs_unexport_children(). In that case, we do not need separate functions anymore either. We also really want to remove sysfs irrespective of whether or not the chip will be removed as a result of pwmchip_remove(). We can only assume that the driver will be gone after that, so we shouldn't leave any dangling sysfs files around. This warning disappears if we move pwmchip_sysfs_unexport() to the top of pwmchip_remove(), pwmchip_sysfs_unexport_children(). That way it is also outside of the pwm_lock section, which indeed doesn't seem to be needed. Moving the pwmchip_sysfs_export() call outside of that section also seems fine and it'd be perfectly symmetric with pwmchip_remove() again. So, this patch fixes them. Signed-off-by: Phong Hoang <phong.hoang.wz@renesas.com> [shimoda: revise the commit log and code] Fixes:76abbdde2d
("pwm: Add sysfs interface") Fixes:0733424c9b
("pwm: Unexport children before chip removal") Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Tested-by: Hoan Nguyen An <na-hoan@jinso.co.jp> Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Simon Horman <horms+renesas@verge.net.au> Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de> Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
610 lines
16 KiB
C
610 lines
16 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_PWM_H
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#define __LINUX_PWM_H
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#include <linux/err.h>
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#include <linux/mutex.h>
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#include <linux/of.h>
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struct pwm_capture;
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struct seq_file;
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struct pwm_chip;
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/**
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* enum pwm_polarity - polarity of a PWM signal
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* @PWM_POLARITY_NORMAL: a high signal for the duration of the duty-
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* cycle, followed by a low signal for the remainder of the pulse
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* period
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* @PWM_POLARITY_INVERSED: a low signal for the duration of the duty-
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* cycle, followed by a high signal for the remainder of the pulse
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* period
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*/
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enum pwm_polarity {
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PWM_POLARITY_NORMAL,
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PWM_POLARITY_INVERSED,
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};
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/**
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* struct pwm_args - board-dependent PWM arguments
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* @period: reference period
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* @polarity: reference polarity
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*
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* This structure describes board-dependent arguments attached to a PWM
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* device. These arguments are usually retrieved from the PWM lookup table or
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* device tree.
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*
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* Do not confuse this with the PWM state: PWM arguments represent the initial
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* configuration that users want to use on this PWM device rather than the
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* current PWM hardware state.
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*/
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struct pwm_args {
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unsigned int period;
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enum pwm_polarity polarity;
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};
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enum {
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PWMF_REQUESTED = 1 << 0,
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PWMF_EXPORTED = 1 << 1,
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};
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/*
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* struct pwm_state - state of a PWM channel
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* @period: PWM period (in nanoseconds)
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* @duty_cycle: PWM duty cycle (in nanoseconds)
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* @polarity: PWM polarity
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* @enabled: PWM enabled status
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*/
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struct pwm_state {
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unsigned int period;
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unsigned int duty_cycle;
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enum pwm_polarity polarity;
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bool enabled;
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};
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/**
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* struct pwm_device - PWM channel object
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* @label: name of the PWM device
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* @flags: flags associated with the PWM device
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* @hwpwm: per-chip relative index of the PWM device
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* @pwm: global index of the PWM device
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* @chip: PWM chip providing this PWM device
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* @chip_data: chip-private data associated with the PWM device
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* @args: PWM arguments
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* @state: curent PWM channel state
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*/
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struct pwm_device {
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const char *label;
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unsigned long flags;
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unsigned int hwpwm;
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unsigned int pwm;
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struct pwm_chip *chip;
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void *chip_data;
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struct pwm_args args;
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struct pwm_state state;
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};
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/**
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* pwm_get_state() - retrieve the current PWM state
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* @pwm: PWM device
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* @state: state to fill with the current PWM state
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*/
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static inline void pwm_get_state(const struct pwm_device *pwm,
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struct pwm_state *state)
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{
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*state = pwm->state;
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}
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static inline bool pwm_is_enabled(const struct pwm_device *pwm)
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{
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return state.enabled;
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}
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static inline void pwm_set_period(struct pwm_device *pwm, unsigned int period)
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{
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if (pwm)
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pwm->state.period = period;
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}
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static inline unsigned int pwm_get_period(const struct pwm_device *pwm)
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{
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return state.period;
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}
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static inline void pwm_set_duty_cycle(struct pwm_device *pwm, unsigned int duty)
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{
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if (pwm)
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pwm->state.duty_cycle = duty;
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}
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static inline unsigned int pwm_get_duty_cycle(const struct pwm_device *pwm)
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{
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return state.duty_cycle;
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}
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static inline enum pwm_polarity pwm_get_polarity(const struct pwm_device *pwm)
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{
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struct pwm_state state;
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pwm_get_state(pwm, &state);
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return state.polarity;
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}
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static inline void pwm_get_args(const struct pwm_device *pwm,
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struct pwm_args *args)
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{
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*args = pwm->args;
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}
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/**
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* pwm_init_state() - prepare a new state to be applied with pwm_apply_state()
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* @pwm: PWM device
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* @state: state to fill with the prepared PWM state
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*
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* This functions prepares a state that can later be tweaked and applied
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* to the PWM device with pwm_apply_state(). This is a convenient function
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* that first retrieves the current PWM state and the replaces the period
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* and polarity fields with the reference values defined in pwm->args.
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* Once the function returns, you can adjust the ->enabled and ->duty_cycle
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* fields according to your needs before calling pwm_apply_state().
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*
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* ->duty_cycle is initially set to zero to avoid cases where the current
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* ->duty_cycle value exceed the pwm_args->period one, which would trigger
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* an error if the user calls pwm_apply_state() without adjusting ->duty_cycle
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* first.
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*/
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static inline void pwm_init_state(const struct pwm_device *pwm,
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struct pwm_state *state)
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{
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struct pwm_args args;
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/* First get the current state. */
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pwm_get_state(pwm, state);
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/* Then fill it with the reference config */
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pwm_get_args(pwm, &args);
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state->period = args.period;
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state->polarity = args.polarity;
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state->duty_cycle = 0;
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}
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/**
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* pwm_get_relative_duty_cycle() - Get a relative duty cycle value
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* @state: PWM state to extract the duty cycle from
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* @scale: target scale of the relative duty cycle
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*
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* This functions converts the absolute duty cycle stored in @state (expressed
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* in nanosecond) into a value relative to the period.
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*
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* For example if you want to get the duty_cycle expressed in percent, call:
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*
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* pwm_get_state(pwm, &state);
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* duty = pwm_get_relative_duty_cycle(&state, 100);
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*/
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static inline unsigned int
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pwm_get_relative_duty_cycle(const struct pwm_state *state, unsigned int scale)
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{
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if (!state->period)
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return 0;
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return DIV_ROUND_CLOSEST_ULL((u64)state->duty_cycle * scale,
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state->period);
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}
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/**
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* pwm_set_relative_duty_cycle() - Set a relative duty cycle value
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* @state: PWM state to fill
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* @duty_cycle: relative duty cycle value
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* @scale: scale in which @duty_cycle is expressed
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*
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* This functions converts a relative into an absolute duty cycle (expressed
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* in nanoseconds), and puts the result in state->duty_cycle.
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*
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* For example if you want to configure a 50% duty cycle, call:
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*
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* pwm_init_state(pwm, &state);
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* pwm_set_relative_duty_cycle(&state, 50, 100);
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* pwm_apply_state(pwm, &state);
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*
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* This functions returns -EINVAL if @duty_cycle and/or @scale are
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* inconsistent (@scale == 0 or @duty_cycle > @scale).
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*/
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static inline int
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pwm_set_relative_duty_cycle(struct pwm_state *state, unsigned int duty_cycle,
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unsigned int scale)
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{
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if (!scale || duty_cycle > scale)
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return -EINVAL;
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state->duty_cycle = DIV_ROUND_CLOSEST_ULL((u64)duty_cycle *
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state->period,
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scale);
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return 0;
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}
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/**
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* struct pwm_ops - PWM controller operations
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* @request: optional hook for requesting a PWM
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* @free: optional hook for freeing a PWM
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* @capture: capture and report PWM signal
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* @apply: atomically apply a new PWM config. The state argument
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* should be adjusted with the real hardware config (if the
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* approximate the period or duty_cycle value, state should
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* reflect it)
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* @get_state: get the current PWM state. This function is only
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* called once per PWM device when the PWM chip is
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* registered.
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* @owner: helps prevent removal of modules exporting active PWMs
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* @config: configure duty cycles and period length for this PWM
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* @set_polarity: configure the polarity of this PWM
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* @enable: enable PWM output toggling
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* @disable: disable PWM output toggling
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*/
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struct pwm_ops {
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int (*request)(struct pwm_chip *chip, struct pwm_device *pwm);
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void (*free)(struct pwm_chip *chip, struct pwm_device *pwm);
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int (*capture)(struct pwm_chip *chip, struct pwm_device *pwm,
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struct pwm_capture *result, unsigned long timeout);
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int (*apply)(struct pwm_chip *chip, struct pwm_device *pwm,
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struct pwm_state *state);
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void (*get_state)(struct pwm_chip *chip, struct pwm_device *pwm,
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struct pwm_state *state);
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struct module *owner;
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/* Only used by legacy drivers */
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int (*config)(struct pwm_chip *chip, struct pwm_device *pwm,
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int duty_ns, int period_ns);
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int (*set_polarity)(struct pwm_chip *chip, struct pwm_device *pwm,
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enum pwm_polarity polarity);
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int (*enable)(struct pwm_chip *chip, struct pwm_device *pwm);
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void (*disable)(struct pwm_chip *chip, struct pwm_device *pwm);
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};
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/**
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* struct pwm_chip - abstract a PWM controller
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* @dev: device providing the PWMs
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* @ops: callbacks for this PWM controller
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* @base: number of first PWM controlled by this chip
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* @npwm: number of PWMs controlled by this chip
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* @of_xlate: request a PWM device given a device tree PWM specifier
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* @of_pwm_n_cells: number of cells expected in the device tree PWM specifier
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* @list: list node for internal use
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* @pwms: array of PWM devices allocated by the framework
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*/
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struct pwm_chip {
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struct device *dev;
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const struct pwm_ops *ops;
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int base;
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unsigned int npwm;
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struct pwm_device * (*of_xlate)(struct pwm_chip *pc,
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const struct of_phandle_args *args);
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unsigned int of_pwm_n_cells;
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/* only used internally by the PWM framework */
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struct list_head list;
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struct pwm_device *pwms;
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};
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/**
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* struct pwm_capture - PWM capture data
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* @period: period of the PWM signal (in nanoseconds)
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* @duty_cycle: duty cycle of the PWM signal (in nanoseconds)
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*/
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struct pwm_capture {
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unsigned int period;
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unsigned int duty_cycle;
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};
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#if IS_ENABLED(CONFIG_PWM)
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/* PWM user APIs */
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struct pwm_device *pwm_request(int pwm_id, const char *label);
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void pwm_free(struct pwm_device *pwm);
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int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state);
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int pwm_adjust_config(struct pwm_device *pwm);
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/**
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* pwm_config() - change a PWM device configuration
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* @pwm: PWM device
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* @duty_ns: "on" time (in nanoseconds)
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* @period_ns: duration (in nanoseconds) of one cycle
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*
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* Returns: 0 on success or a negative error code on failure.
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*/
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static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
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int period_ns)
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{
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struct pwm_state state;
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if (!pwm)
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return -EINVAL;
|
|
|
|
if (duty_ns < 0 || period_ns < 0)
|
|
return -EINVAL;
|
|
|
|
pwm_get_state(pwm, &state);
|
|
if (state.duty_cycle == duty_ns && state.period == period_ns)
|
|
return 0;
|
|
|
|
state.duty_cycle = duty_ns;
|
|
state.period = period_ns;
|
|
return pwm_apply_state(pwm, &state);
|
|
}
|
|
|
|
/**
|
|
* pwm_enable() - start a PWM output toggling
|
|
* @pwm: PWM device
|
|
*
|
|
* Returns: 0 on success or a negative error code on failure.
|
|
*/
|
|
static inline int pwm_enable(struct pwm_device *pwm)
|
|
{
|
|
struct pwm_state state;
|
|
|
|
if (!pwm)
|
|
return -EINVAL;
|
|
|
|
pwm_get_state(pwm, &state);
|
|
if (state.enabled)
|
|
return 0;
|
|
|
|
state.enabled = true;
|
|
return pwm_apply_state(pwm, &state);
|
|
}
|
|
|
|
/**
|
|
* pwm_disable() - stop a PWM output toggling
|
|
* @pwm: PWM device
|
|
*/
|
|
static inline void pwm_disable(struct pwm_device *pwm)
|
|
{
|
|
struct pwm_state state;
|
|
|
|
if (!pwm)
|
|
return;
|
|
|
|
pwm_get_state(pwm, &state);
|
|
if (!state.enabled)
|
|
return;
|
|
|
|
state.enabled = false;
|
|
pwm_apply_state(pwm, &state);
|
|
}
|
|
|
|
/* PWM provider APIs */
|
|
int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
|
|
unsigned long timeout);
|
|
int pwm_set_chip_data(struct pwm_device *pwm, void *data);
|
|
void *pwm_get_chip_data(struct pwm_device *pwm);
|
|
|
|
int pwmchip_add_with_polarity(struct pwm_chip *chip,
|
|
enum pwm_polarity polarity);
|
|
int pwmchip_add(struct pwm_chip *chip);
|
|
int pwmchip_remove(struct pwm_chip *chip);
|
|
struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
|
|
unsigned int index,
|
|
const char *label);
|
|
|
|
struct pwm_device *of_pwm_xlate_with_flags(struct pwm_chip *pc,
|
|
const struct of_phandle_args *args);
|
|
|
|
struct pwm_device *pwm_get(struct device *dev, const char *con_id);
|
|
struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id);
|
|
void pwm_put(struct pwm_device *pwm);
|
|
|
|
struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id);
|
|
struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
|
|
const char *con_id);
|
|
void devm_pwm_put(struct device *dev, struct pwm_device *pwm);
|
|
#else
|
|
static inline struct pwm_device *pwm_request(int pwm_id, const char *label)
|
|
{
|
|
return ERR_PTR(-ENODEV);
|
|
}
|
|
|
|
static inline void pwm_free(struct pwm_device *pwm)
|
|
{
|
|
}
|
|
|
|
static inline int pwm_apply_state(struct pwm_device *pwm,
|
|
const struct pwm_state *state)
|
|
{
|
|
return -ENOTSUPP;
|
|
}
|
|
|
|
static inline int pwm_adjust_config(struct pwm_device *pwm)
|
|
{
|
|
return -ENOTSUPP;
|
|
}
|
|
|
|
static inline int pwm_config(struct pwm_device *pwm, int duty_ns,
|
|
int period_ns)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline int pwm_capture(struct pwm_device *pwm,
|
|
struct pwm_capture *result,
|
|
unsigned long timeout)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline int pwm_enable(struct pwm_device *pwm)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline void pwm_disable(struct pwm_device *pwm)
|
|
{
|
|
}
|
|
|
|
static inline int pwm_set_chip_data(struct pwm_device *pwm, void *data)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline void *pwm_get_chip_data(struct pwm_device *pwm)
|
|
{
|
|
return NULL;
|
|
}
|
|
|
|
static inline int pwmchip_add(struct pwm_chip *chip)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline int pwmchip_add_inversed(struct pwm_chip *chip)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline int pwmchip_remove(struct pwm_chip *chip)
|
|
{
|
|
return -EINVAL;
|
|
}
|
|
|
|
static inline struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
|
|
unsigned int index,
|
|
const char *label)
|
|
{
|
|
return ERR_PTR(-ENODEV);
|
|
}
|
|
|
|
static inline struct pwm_device *pwm_get(struct device *dev,
|
|
const char *consumer)
|
|
{
|
|
return ERR_PTR(-ENODEV);
|
|
}
|
|
|
|
static inline struct pwm_device *of_pwm_get(struct device_node *np,
|
|
const char *con_id)
|
|
{
|
|
return ERR_PTR(-ENODEV);
|
|
}
|
|
|
|
static inline void pwm_put(struct pwm_device *pwm)
|
|
{
|
|
}
|
|
|
|
static inline struct pwm_device *devm_pwm_get(struct device *dev,
|
|
const char *consumer)
|
|
{
|
|
return ERR_PTR(-ENODEV);
|
|
}
|
|
|
|
static inline struct pwm_device *devm_of_pwm_get(struct device *dev,
|
|
struct device_node *np,
|
|
const char *con_id)
|
|
{
|
|
return ERR_PTR(-ENODEV);
|
|
}
|
|
|
|
static inline void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
static inline void pwm_apply_args(struct pwm_device *pwm)
|
|
{
|
|
struct pwm_state state = { };
|
|
|
|
/*
|
|
* PWM users calling pwm_apply_args() expect to have a fresh config
|
|
* where the polarity and period are set according to pwm_args info.
|
|
* The problem is, polarity can only be changed when the PWM is
|
|
* disabled.
|
|
*
|
|
* PWM drivers supporting hardware readout may declare the PWM device
|
|
* as enabled, and prevent polarity setting, which changes from the
|
|
* existing behavior, where all PWM devices are declared as disabled
|
|
* at startup (even if they are actually enabled), thus authorizing
|
|
* polarity setting.
|
|
*
|
|
* To fulfill this requirement, we apply a new state which disables
|
|
* the PWM device and set the reference period and polarity config.
|
|
*
|
|
* Note that PWM users requiring a smooth handover between the
|
|
* bootloader and the kernel (like critical regulators controlled by
|
|
* PWM devices) will have to switch to the atomic API and avoid calling
|
|
* pwm_apply_args().
|
|
*/
|
|
|
|
state.enabled = false;
|
|
state.polarity = pwm->args.polarity;
|
|
state.period = pwm->args.period;
|
|
|
|
pwm_apply_state(pwm, &state);
|
|
}
|
|
|
|
struct pwm_lookup {
|
|
struct list_head list;
|
|
const char *provider;
|
|
unsigned int index;
|
|
const char *dev_id;
|
|
const char *con_id;
|
|
unsigned int period;
|
|
enum pwm_polarity polarity;
|
|
const char *module; /* optional, may be NULL */
|
|
};
|
|
|
|
#define PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, \
|
|
_period, _polarity, _module) \
|
|
{ \
|
|
.provider = _provider, \
|
|
.index = _index, \
|
|
.dev_id = _dev_id, \
|
|
.con_id = _con_id, \
|
|
.period = _period, \
|
|
.polarity = _polarity, \
|
|
.module = _module, \
|
|
}
|
|
|
|
#define PWM_LOOKUP(_provider, _index, _dev_id, _con_id, _period, _polarity) \
|
|
PWM_LOOKUP_WITH_MODULE(_provider, _index, _dev_id, _con_id, _period, \
|
|
_polarity, NULL)
|
|
|
|
#if IS_ENABLED(CONFIG_PWM)
|
|
void pwm_add_table(struct pwm_lookup *table, size_t num);
|
|
void pwm_remove_table(struct pwm_lookup *table, size_t num);
|
|
#else
|
|
static inline void pwm_add_table(struct pwm_lookup *table, size_t num)
|
|
{
|
|
}
|
|
|
|
static inline void pwm_remove_table(struct pwm_lookup *table, size_t num)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
#ifdef CONFIG_PWM_SYSFS
|
|
void pwmchip_sysfs_export(struct pwm_chip *chip);
|
|
void pwmchip_sysfs_unexport(struct pwm_chip *chip);
|
|
#else
|
|
static inline void pwmchip_sysfs_export(struct pwm_chip *chip)
|
|
{
|
|
}
|
|
|
|
static inline void pwmchip_sysfs_unexport(struct pwm_chip *chip)
|
|
{
|
|
}
|
|
#endif /* CONFIG_PWM_SYSFS */
|
|
|
|
#endif /* __LINUX_PWM_H */
|