mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-30 08:02:30 +00:00
347ab94803
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>
1072 lines
24 KiB
C
1072 lines
24 KiB
C
/*
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* Generic pwmlib implementation
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*
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* Copyright (C) 2011 Sascha Hauer <s.hauer@pengutronix.de>
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* Copyright (C) 2011-2012 Avionic Design GmbH
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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; either version 2, or (at your option)
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* any later version.
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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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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/module.h>
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#include <linux/pwm.h>
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#include <linux/radix-tree.h>
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#include <linux/list.h>
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#include <linux/mutex.h>
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#include <linux/err.h>
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#include <linux/slab.h>
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#include <linux/device.h>
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#include <linux/debugfs.h>
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#include <linux/seq_file.h>
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#include <dt-bindings/pwm/pwm.h>
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#define MAX_PWMS 1024
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static DEFINE_MUTEX(pwm_lookup_lock);
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static LIST_HEAD(pwm_lookup_list);
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static DEFINE_MUTEX(pwm_lock);
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static LIST_HEAD(pwm_chips);
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static DECLARE_BITMAP(allocated_pwms, MAX_PWMS);
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static RADIX_TREE(pwm_tree, GFP_KERNEL);
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static struct pwm_device *pwm_to_device(unsigned int pwm)
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{
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return radix_tree_lookup(&pwm_tree, pwm);
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}
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static int alloc_pwms(int pwm, unsigned int count)
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{
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unsigned int from = 0;
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unsigned int start;
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if (pwm >= MAX_PWMS)
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return -EINVAL;
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if (pwm >= 0)
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from = pwm;
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start = bitmap_find_next_zero_area(allocated_pwms, MAX_PWMS, from,
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count, 0);
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if (pwm >= 0 && start != pwm)
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return -EEXIST;
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if (start + count > MAX_PWMS)
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return -ENOSPC;
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return start;
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}
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static void free_pwms(struct pwm_chip *chip)
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{
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unsigned int i;
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for (i = 0; i < chip->npwm; i++) {
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struct pwm_device *pwm = &chip->pwms[i];
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radix_tree_delete(&pwm_tree, pwm->pwm);
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}
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bitmap_clear(allocated_pwms, chip->base, chip->npwm);
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kfree(chip->pwms);
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chip->pwms = NULL;
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}
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static struct pwm_chip *pwmchip_find_by_name(const char *name)
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{
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struct pwm_chip *chip;
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if (!name)
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return NULL;
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mutex_lock(&pwm_lock);
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list_for_each_entry(chip, &pwm_chips, list) {
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const char *chip_name = dev_name(chip->dev);
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if (chip_name && strcmp(chip_name, name) == 0) {
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mutex_unlock(&pwm_lock);
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return chip;
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}
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}
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mutex_unlock(&pwm_lock);
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return NULL;
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}
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static int pwm_device_request(struct pwm_device *pwm, const char *label)
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{
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int err;
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if (test_bit(PWMF_REQUESTED, &pwm->flags))
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return -EBUSY;
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if (!try_module_get(pwm->chip->ops->owner))
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return -ENODEV;
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if (pwm->chip->ops->request) {
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err = pwm->chip->ops->request(pwm->chip, pwm);
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if (err) {
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module_put(pwm->chip->ops->owner);
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return err;
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}
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}
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set_bit(PWMF_REQUESTED, &pwm->flags);
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pwm->label = label;
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return 0;
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}
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struct pwm_device *
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of_pwm_xlate_with_flags(struct pwm_chip *pc, const struct of_phandle_args *args)
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{
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struct pwm_device *pwm;
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/* check, whether the driver supports a third cell for flags */
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if (pc->of_pwm_n_cells < 3)
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return ERR_PTR(-EINVAL);
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/* flags in the third cell are optional */
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if (args->args_count < 2)
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return ERR_PTR(-EINVAL);
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if (args->args[0] >= pc->npwm)
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return ERR_PTR(-EINVAL);
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pwm = pwm_request_from_chip(pc, args->args[0], NULL);
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if (IS_ERR(pwm))
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return pwm;
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pwm->args.period = args->args[1];
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pwm->args.polarity = PWM_POLARITY_NORMAL;
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if (args->args_count > 2 && args->args[2] & PWM_POLARITY_INVERTED)
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pwm->args.polarity = PWM_POLARITY_INVERSED;
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return pwm;
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}
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EXPORT_SYMBOL_GPL(of_pwm_xlate_with_flags);
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static struct pwm_device *
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of_pwm_simple_xlate(struct pwm_chip *pc, const struct of_phandle_args *args)
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{
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struct pwm_device *pwm;
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/* sanity check driver support */
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if (pc->of_pwm_n_cells < 2)
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return ERR_PTR(-EINVAL);
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/* all cells are required */
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if (args->args_count != pc->of_pwm_n_cells)
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return ERR_PTR(-EINVAL);
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if (args->args[0] >= pc->npwm)
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return ERR_PTR(-EINVAL);
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pwm = pwm_request_from_chip(pc, args->args[0], NULL);
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if (IS_ERR(pwm))
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return pwm;
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pwm->args.period = args->args[1];
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return pwm;
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}
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static void of_pwmchip_add(struct pwm_chip *chip)
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{
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if (!chip->dev || !chip->dev->of_node)
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return;
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if (!chip->of_xlate) {
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chip->of_xlate = of_pwm_simple_xlate;
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chip->of_pwm_n_cells = 2;
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}
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of_node_get(chip->dev->of_node);
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}
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static void of_pwmchip_remove(struct pwm_chip *chip)
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{
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if (chip->dev)
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of_node_put(chip->dev->of_node);
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}
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/**
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* pwm_set_chip_data() - set private chip data for a PWM
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* @pwm: PWM device
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* @data: pointer to chip-specific data
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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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int pwm_set_chip_data(struct pwm_device *pwm, void *data)
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{
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if (!pwm)
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return -EINVAL;
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pwm->chip_data = data;
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return 0;
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}
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EXPORT_SYMBOL_GPL(pwm_set_chip_data);
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/**
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* pwm_get_chip_data() - get private chip data for a PWM
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* @pwm: PWM device
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*
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* Returns: A pointer to the chip-private data for the PWM device.
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*/
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void *pwm_get_chip_data(struct pwm_device *pwm)
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{
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return pwm ? pwm->chip_data : NULL;
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}
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EXPORT_SYMBOL_GPL(pwm_get_chip_data);
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static bool pwm_ops_check(const struct pwm_ops *ops)
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{
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/* driver supports legacy, non-atomic operation */
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if (ops->config && ops->enable && ops->disable)
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return true;
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/* driver supports atomic operation */
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if (ops->apply)
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return true;
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return false;
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}
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/**
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* pwmchip_add_with_polarity() - register a new PWM chip
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* @chip: the PWM chip to add
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* @polarity: initial polarity of PWM channels
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*
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* Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
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* will be used. The initial polarity for all channels is specified by the
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* @polarity parameter.
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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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int pwmchip_add_with_polarity(struct pwm_chip *chip,
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enum pwm_polarity polarity)
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{
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struct pwm_device *pwm;
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unsigned int i;
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int ret;
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if (!chip || !chip->dev || !chip->ops || !chip->npwm)
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return -EINVAL;
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if (!pwm_ops_check(chip->ops))
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return -EINVAL;
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mutex_lock(&pwm_lock);
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ret = alloc_pwms(chip->base, chip->npwm);
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if (ret < 0)
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goto out;
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chip->pwms = kcalloc(chip->npwm, sizeof(*pwm), GFP_KERNEL);
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if (!chip->pwms) {
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ret = -ENOMEM;
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goto out;
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}
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chip->base = ret;
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for (i = 0; i < chip->npwm; i++) {
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pwm = &chip->pwms[i];
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pwm->chip = chip;
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pwm->pwm = chip->base + i;
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pwm->hwpwm = i;
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pwm->state.polarity = polarity;
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if (chip->ops->get_state)
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chip->ops->get_state(chip, pwm, &pwm->state);
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radix_tree_insert(&pwm_tree, pwm->pwm, pwm);
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}
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bitmap_set(allocated_pwms, chip->base, chip->npwm);
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INIT_LIST_HEAD(&chip->list);
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list_add(&chip->list, &pwm_chips);
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ret = 0;
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if (IS_ENABLED(CONFIG_OF))
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of_pwmchip_add(chip);
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out:
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mutex_unlock(&pwm_lock);
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if (!ret)
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pwmchip_sysfs_export(chip);
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return ret;
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}
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EXPORT_SYMBOL_GPL(pwmchip_add_with_polarity);
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/**
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* pwmchip_add() - register a new PWM chip
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* @chip: the PWM chip to add
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*
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* Register a new PWM chip. If chip->base < 0 then a dynamically assigned base
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* will be used. The initial polarity for all channels is normal.
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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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int pwmchip_add(struct pwm_chip *chip)
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{
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return pwmchip_add_with_polarity(chip, PWM_POLARITY_NORMAL);
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}
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EXPORT_SYMBOL_GPL(pwmchip_add);
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/**
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* pwmchip_remove() - remove a PWM chip
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* @chip: the PWM chip to remove
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*
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* Removes a PWM chip. This function may return busy if the PWM chip provides
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* a PWM device that is still requested.
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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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int pwmchip_remove(struct pwm_chip *chip)
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{
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unsigned int i;
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int ret = 0;
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pwmchip_sysfs_unexport(chip);
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mutex_lock(&pwm_lock);
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|
|
for (i = 0; i < chip->npwm; i++) {
|
|
struct pwm_device *pwm = &chip->pwms[i];
|
|
|
|
if (test_bit(PWMF_REQUESTED, &pwm->flags)) {
|
|
ret = -EBUSY;
|
|
goto out;
|
|
}
|
|
}
|
|
|
|
list_del_init(&chip->list);
|
|
|
|
if (IS_ENABLED(CONFIG_OF))
|
|
of_pwmchip_remove(chip);
|
|
|
|
free_pwms(chip);
|
|
|
|
out:
|
|
mutex_unlock(&pwm_lock);
|
|
return ret;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwmchip_remove);
|
|
|
|
/**
|
|
* pwm_request() - request a PWM device
|
|
* @pwm: global PWM device index
|
|
* @label: PWM device label
|
|
*
|
|
* This function is deprecated, use pwm_get() instead.
|
|
*
|
|
* Returns: A pointer to a PWM device or an ERR_PTR()-encoded error code on
|
|
* failure.
|
|
*/
|
|
struct pwm_device *pwm_request(int pwm, const char *label)
|
|
{
|
|
struct pwm_device *dev;
|
|
int err;
|
|
|
|
if (pwm < 0 || pwm >= MAX_PWMS)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
mutex_lock(&pwm_lock);
|
|
|
|
dev = pwm_to_device(pwm);
|
|
if (!dev) {
|
|
dev = ERR_PTR(-EPROBE_DEFER);
|
|
goto out;
|
|
}
|
|
|
|
err = pwm_device_request(dev, label);
|
|
if (err < 0)
|
|
dev = ERR_PTR(err);
|
|
|
|
out:
|
|
mutex_unlock(&pwm_lock);
|
|
|
|
return dev;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwm_request);
|
|
|
|
/**
|
|
* pwm_request_from_chip() - request a PWM device relative to a PWM chip
|
|
* @chip: PWM chip
|
|
* @index: per-chip index of the PWM to request
|
|
* @label: a literal description string of this PWM
|
|
*
|
|
* Returns: A pointer to the PWM device at the given index of the given PWM
|
|
* chip. A negative error code is returned if the index is not valid for the
|
|
* specified PWM chip or if the PWM device cannot be requested.
|
|
*/
|
|
struct pwm_device *pwm_request_from_chip(struct pwm_chip *chip,
|
|
unsigned int index,
|
|
const char *label)
|
|
{
|
|
struct pwm_device *pwm;
|
|
int err;
|
|
|
|
if (!chip || index >= chip->npwm)
|
|
return ERR_PTR(-EINVAL);
|
|
|
|
mutex_lock(&pwm_lock);
|
|
pwm = &chip->pwms[index];
|
|
|
|
err = pwm_device_request(pwm, label);
|
|
if (err < 0)
|
|
pwm = ERR_PTR(err);
|
|
|
|
mutex_unlock(&pwm_lock);
|
|
return pwm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwm_request_from_chip);
|
|
|
|
/**
|
|
* pwm_free() - free a PWM device
|
|
* @pwm: PWM device
|
|
*
|
|
* This function is deprecated, use pwm_put() instead.
|
|
*/
|
|
void pwm_free(struct pwm_device *pwm)
|
|
{
|
|
pwm_put(pwm);
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwm_free);
|
|
|
|
/**
|
|
* pwm_apply_state() - atomically apply a new state to a PWM device
|
|
* @pwm: PWM device
|
|
* @state: new state to apply. This can be adjusted by the PWM driver
|
|
* if the requested config is not achievable, for example,
|
|
* ->duty_cycle and ->period might be approximated.
|
|
*/
|
|
int pwm_apply_state(struct pwm_device *pwm, struct pwm_state *state)
|
|
{
|
|
int err;
|
|
|
|
if (!pwm || !state || !state->period ||
|
|
state->duty_cycle > state->period)
|
|
return -EINVAL;
|
|
|
|
if (state->period == pwm->state.period &&
|
|
state->duty_cycle == pwm->state.duty_cycle &&
|
|
state->polarity == pwm->state.polarity &&
|
|
state->enabled == pwm->state.enabled)
|
|
return 0;
|
|
|
|
if (pwm->chip->ops->apply) {
|
|
err = pwm->chip->ops->apply(pwm->chip, pwm, state);
|
|
if (err)
|
|
return err;
|
|
|
|
pwm->state = *state;
|
|
} else {
|
|
/*
|
|
* FIXME: restore the initial state in case of error.
|
|
*/
|
|
if (state->polarity != pwm->state.polarity) {
|
|
if (!pwm->chip->ops->set_polarity)
|
|
return -ENOTSUPP;
|
|
|
|
/*
|
|
* Changing the polarity of a running PWM is
|
|
* only allowed when the PWM driver implements
|
|
* ->apply().
|
|
*/
|
|
if (pwm->state.enabled) {
|
|
pwm->chip->ops->disable(pwm->chip, pwm);
|
|
pwm->state.enabled = false;
|
|
}
|
|
|
|
err = pwm->chip->ops->set_polarity(pwm->chip, pwm,
|
|
state->polarity);
|
|
if (err)
|
|
return err;
|
|
|
|
pwm->state.polarity = state->polarity;
|
|
}
|
|
|
|
if (state->period != pwm->state.period ||
|
|
state->duty_cycle != pwm->state.duty_cycle) {
|
|
err = pwm->chip->ops->config(pwm->chip, pwm,
|
|
state->duty_cycle,
|
|
state->period);
|
|
if (err)
|
|
return err;
|
|
|
|
pwm->state.duty_cycle = state->duty_cycle;
|
|
pwm->state.period = state->period;
|
|
}
|
|
|
|
if (state->enabled != pwm->state.enabled) {
|
|
if (state->enabled) {
|
|
err = pwm->chip->ops->enable(pwm->chip, pwm);
|
|
if (err)
|
|
return err;
|
|
} else {
|
|
pwm->chip->ops->disable(pwm->chip, pwm);
|
|
}
|
|
|
|
pwm->state.enabled = state->enabled;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwm_apply_state);
|
|
|
|
/**
|
|
* pwm_capture() - capture and report a PWM signal
|
|
* @pwm: PWM device
|
|
* @result: structure to fill with capture result
|
|
* @timeout: time to wait, in milliseconds, before giving up on capture
|
|
*
|
|
* Returns: 0 on success or a negative error code on failure.
|
|
*/
|
|
int pwm_capture(struct pwm_device *pwm, struct pwm_capture *result,
|
|
unsigned long timeout)
|
|
{
|
|
int err;
|
|
|
|
if (!pwm || !pwm->chip->ops)
|
|
return -EINVAL;
|
|
|
|
if (!pwm->chip->ops->capture)
|
|
return -ENOSYS;
|
|
|
|
mutex_lock(&pwm_lock);
|
|
err = pwm->chip->ops->capture(pwm->chip, pwm, result, timeout);
|
|
mutex_unlock(&pwm_lock);
|
|
|
|
return err;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwm_capture);
|
|
|
|
/**
|
|
* pwm_adjust_config() - adjust the current PWM config to the PWM arguments
|
|
* @pwm: PWM device
|
|
*
|
|
* This function will adjust the PWM config to the PWM arguments provided
|
|
* by the DT or PWM lookup table. This is particularly useful to adapt
|
|
* the bootloader config to the Linux one.
|
|
*/
|
|
int pwm_adjust_config(struct pwm_device *pwm)
|
|
{
|
|
struct pwm_state state;
|
|
struct pwm_args pargs;
|
|
|
|
pwm_get_args(pwm, &pargs);
|
|
pwm_get_state(pwm, &state);
|
|
|
|
/*
|
|
* If the current period is zero it means that either the PWM driver
|
|
* does not support initial state retrieval or the PWM has not yet
|
|
* been configured.
|
|
*
|
|
* In either case, we setup the new period and polarity, and assign a
|
|
* duty cycle of 0.
|
|
*/
|
|
if (!state.period) {
|
|
state.duty_cycle = 0;
|
|
state.period = pargs.period;
|
|
state.polarity = pargs.polarity;
|
|
|
|
return pwm_apply_state(pwm, &state);
|
|
}
|
|
|
|
/*
|
|
* Adjust the PWM duty cycle/period based on the period value provided
|
|
* in PWM args.
|
|
*/
|
|
if (pargs.period != state.period) {
|
|
u64 dutycycle = (u64)state.duty_cycle * pargs.period;
|
|
|
|
do_div(dutycycle, state.period);
|
|
state.duty_cycle = dutycycle;
|
|
state.period = pargs.period;
|
|
}
|
|
|
|
/*
|
|
* If the polarity changed, we should also change the duty cycle.
|
|
*/
|
|
if (pargs.polarity != state.polarity) {
|
|
state.polarity = pargs.polarity;
|
|
state.duty_cycle = state.period - state.duty_cycle;
|
|
}
|
|
|
|
return pwm_apply_state(pwm, &state);
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwm_adjust_config);
|
|
|
|
static struct pwm_chip *of_node_to_pwmchip(struct device_node *np)
|
|
{
|
|
struct pwm_chip *chip;
|
|
|
|
mutex_lock(&pwm_lock);
|
|
|
|
list_for_each_entry(chip, &pwm_chips, list)
|
|
if (chip->dev && chip->dev->of_node == np) {
|
|
mutex_unlock(&pwm_lock);
|
|
return chip;
|
|
}
|
|
|
|
mutex_unlock(&pwm_lock);
|
|
|
|
return ERR_PTR(-EPROBE_DEFER);
|
|
}
|
|
|
|
/**
|
|
* of_pwm_get() - request a PWM via the PWM framework
|
|
* @np: device node to get the PWM from
|
|
* @con_id: consumer name
|
|
*
|
|
* Returns the PWM device parsed from the phandle and index specified in the
|
|
* "pwms" property of a device tree node or a negative error-code on failure.
|
|
* Values parsed from the device tree are stored in the returned PWM device
|
|
* object.
|
|
*
|
|
* If con_id is NULL, the first PWM device listed in the "pwms" property will
|
|
* be requested. Otherwise the "pwm-names" property is used to do a reverse
|
|
* lookup of the PWM index. This also means that the "pwm-names" property
|
|
* becomes mandatory for devices that look up the PWM device via the con_id
|
|
* parameter.
|
|
*
|
|
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
|
|
* error code on failure.
|
|
*/
|
|
struct pwm_device *of_pwm_get(struct device_node *np, const char *con_id)
|
|
{
|
|
struct pwm_device *pwm = NULL;
|
|
struct of_phandle_args args;
|
|
struct pwm_chip *pc;
|
|
int index = 0;
|
|
int err;
|
|
|
|
if (con_id) {
|
|
index = of_property_match_string(np, "pwm-names", con_id);
|
|
if (index < 0)
|
|
return ERR_PTR(index);
|
|
}
|
|
|
|
err = of_parse_phandle_with_args(np, "pwms", "#pwm-cells", index,
|
|
&args);
|
|
if (err) {
|
|
pr_err("%s(): can't parse \"pwms\" property\n", __func__);
|
|
return ERR_PTR(err);
|
|
}
|
|
|
|
pc = of_node_to_pwmchip(args.np);
|
|
if (IS_ERR(pc)) {
|
|
if (PTR_ERR(pc) != -EPROBE_DEFER)
|
|
pr_err("%s(): PWM chip not found\n", __func__);
|
|
|
|
pwm = ERR_CAST(pc);
|
|
goto put;
|
|
}
|
|
|
|
pwm = pc->of_xlate(pc, &args);
|
|
if (IS_ERR(pwm))
|
|
goto put;
|
|
|
|
/*
|
|
* If a consumer name was not given, try to look it up from the
|
|
* "pwm-names" property if it exists. Otherwise use the name of
|
|
* the user device node.
|
|
*/
|
|
if (!con_id) {
|
|
err = of_property_read_string_index(np, "pwm-names", index,
|
|
&con_id);
|
|
if (err < 0)
|
|
con_id = np->name;
|
|
}
|
|
|
|
pwm->label = con_id;
|
|
|
|
put:
|
|
of_node_put(args.np);
|
|
|
|
return pwm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(of_pwm_get);
|
|
|
|
/**
|
|
* pwm_add_table() - register PWM device consumers
|
|
* @table: array of consumers to register
|
|
* @num: number of consumers in table
|
|
*/
|
|
void pwm_add_table(struct pwm_lookup *table, size_t num)
|
|
{
|
|
mutex_lock(&pwm_lookup_lock);
|
|
|
|
while (num--) {
|
|
list_add_tail(&table->list, &pwm_lookup_list);
|
|
table++;
|
|
}
|
|
|
|
mutex_unlock(&pwm_lookup_lock);
|
|
}
|
|
|
|
/**
|
|
* pwm_remove_table() - unregister PWM device consumers
|
|
* @table: array of consumers to unregister
|
|
* @num: number of consumers in table
|
|
*/
|
|
void pwm_remove_table(struct pwm_lookup *table, size_t num)
|
|
{
|
|
mutex_lock(&pwm_lookup_lock);
|
|
|
|
while (num--) {
|
|
list_del(&table->list);
|
|
table++;
|
|
}
|
|
|
|
mutex_unlock(&pwm_lookup_lock);
|
|
}
|
|
|
|
/**
|
|
* pwm_get() - look up and request a PWM device
|
|
* @dev: device for PWM consumer
|
|
* @con_id: consumer name
|
|
*
|
|
* Lookup is first attempted using DT. If the device was not instantiated from
|
|
* a device tree, a PWM chip and a relative index is looked up via a table
|
|
* supplied by board setup code (see pwm_add_table()).
|
|
*
|
|
* Once a PWM chip has been found the specified PWM device will be requested
|
|
* and is ready to be used.
|
|
*
|
|
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
|
|
* error code on failure.
|
|
*/
|
|
struct pwm_device *pwm_get(struct device *dev, const char *con_id)
|
|
{
|
|
const char *dev_id = dev ? dev_name(dev) : NULL;
|
|
struct pwm_device *pwm;
|
|
struct pwm_chip *chip;
|
|
unsigned int best = 0;
|
|
struct pwm_lookup *p, *chosen = NULL;
|
|
unsigned int match;
|
|
int err;
|
|
|
|
/* look up via DT first */
|
|
if (IS_ENABLED(CONFIG_OF) && dev && dev->of_node)
|
|
return of_pwm_get(dev->of_node, con_id);
|
|
|
|
/*
|
|
* We look up the provider in the static table typically provided by
|
|
* board setup code. We first try to lookup the consumer device by
|
|
* name. If the consumer device was passed in as NULL or if no match
|
|
* was found, we try to find the consumer by directly looking it up
|
|
* by name.
|
|
*
|
|
* If a match is found, the provider PWM chip is looked up by name
|
|
* and a PWM device is requested using the PWM device per-chip index.
|
|
*
|
|
* The lookup algorithm was shamelessly taken from the clock
|
|
* framework:
|
|
*
|
|
* We do slightly fuzzy matching here:
|
|
* An entry with a NULL ID is assumed to be a wildcard.
|
|
* If an entry has a device ID, it must match
|
|
* If an entry has a connection ID, it must match
|
|
* Then we take the most specific entry - with the following order
|
|
* of precedence: dev+con > dev only > con only.
|
|
*/
|
|
mutex_lock(&pwm_lookup_lock);
|
|
|
|
list_for_each_entry(p, &pwm_lookup_list, list) {
|
|
match = 0;
|
|
|
|
if (p->dev_id) {
|
|
if (!dev_id || strcmp(p->dev_id, dev_id))
|
|
continue;
|
|
|
|
match += 2;
|
|
}
|
|
|
|
if (p->con_id) {
|
|
if (!con_id || strcmp(p->con_id, con_id))
|
|
continue;
|
|
|
|
match += 1;
|
|
}
|
|
|
|
if (match > best) {
|
|
chosen = p;
|
|
|
|
if (match != 3)
|
|
best = match;
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
|
|
mutex_unlock(&pwm_lookup_lock);
|
|
|
|
if (!chosen)
|
|
return ERR_PTR(-ENODEV);
|
|
|
|
chip = pwmchip_find_by_name(chosen->provider);
|
|
|
|
/*
|
|
* If the lookup entry specifies a module, load the module and retry
|
|
* the PWM chip lookup. This can be used to work around driver load
|
|
* ordering issues if driver's can't be made to properly support the
|
|
* deferred probe mechanism.
|
|
*/
|
|
if (!chip && chosen->module) {
|
|
err = request_module(chosen->module);
|
|
if (err == 0)
|
|
chip = pwmchip_find_by_name(chosen->provider);
|
|
}
|
|
|
|
if (!chip)
|
|
return ERR_PTR(-EPROBE_DEFER);
|
|
|
|
pwm = pwm_request_from_chip(chip, chosen->index, con_id ?: dev_id);
|
|
if (IS_ERR(pwm))
|
|
return pwm;
|
|
|
|
pwm->args.period = chosen->period;
|
|
pwm->args.polarity = chosen->polarity;
|
|
|
|
return pwm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwm_get);
|
|
|
|
/**
|
|
* pwm_put() - release a PWM device
|
|
* @pwm: PWM device
|
|
*/
|
|
void pwm_put(struct pwm_device *pwm)
|
|
{
|
|
if (!pwm)
|
|
return;
|
|
|
|
mutex_lock(&pwm_lock);
|
|
|
|
if (!test_and_clear_bit(PWMF_REQUESTED, &pwm->flags)) {
|
|
pr_warn("PWM device already freed\n");
|
|
goto out;
|
|
}
|
|
|
|
if (pwm->chip->ops->free)
|
|
pwm->chip->ops->free(pwm->chip, pwm);
|
|
|
|
pwm->label = NULL;
|
|
|
|
module_put(pwm->chip->ops->owner);
|
|
out:
|
|
mutex_unlock(&pwm_lock);
|
|
}
|
|
EXPORT_SYMBOL_GPL(pwm_put);
|
|
|
|
static void devm_pwm_release(struct device *dev, void *res)
|
|
{
|
|
pwm_put(*(struct pwm_device **)res);
|
|
}
|
|
|
|
/**
|
|
* devm_pwm_get() - resource managed pwm_get()
|
|
* @dev: device for PWM consumer
|
|
* @con_id: consumer name
|
|
*
|
|
* This function performs like pwm_get() but the acquired PWM device will
|
|
* automatically be released on driver detach.
|
|
*
|
|
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
|
|
* error code on failure.
|
|
*/
|
|
struct pwm_device *devm_pwm_get(struct device *dev, const char *con_id)
|
|
{
|
|
struct pwm_device **ptr, *pwm;
|
|
|
|
ptr = devres_alloc(devm_pwm_release, sizeof(*ptr), GFP_KERNEL);
|
|
if (!ptr)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
pwm = pwm_get(dev, con_id);
|
|
if (!IS_ERR(pwm)) {
|
|
*ptr = pwm;
|
|
devres_add(dev, ptr);
|
|
} else {
|
|
devres_free(ptr);
|
|
}
|
|
|
|
return pwm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(devm_pwm_get);
|
|
|
|
/**
|
|
* devm_of_pwm_get() - resource managed of_pwm_get()
|
|
* @dev: device for PWM consumer
|
|
* @np: device node to get the PWM from
|
|
* @con_id: consumer name
|
|
*
|
|
* This function performs like of_pwm_get() but the acquired PWM device will
|
|
* automatically be released on driver detach.
|
|
*
|
|
* Returns: A pointer to the requested PWM device or an ERR_PTR()-encoded
|
|
* error code on failure.
|
|
*/
|
|
struct pwm_device *devm_of_pwm_get(struct device *dev, struct device_node *np,
|
|
const char *con_id)
|
|
{
|
|
struct pwm_device **ptr, *pwm;
|
|
|
|
ptr = devres_alloc(devm_pwm_release, sizeof(*ptr), GFP_KERNEL);
|
|
if (!ptr)
|
|
return ERR_PTR(-ENOMEM);
|
|
|
|
pwm = of_pwm_get(np, con_id);
|
|
if (!IS_ERR(pwm)) {
|
|
*ptr = pwm;
|
|
devres_add(dev, ptr);
|
|
} else {
|
|
devres_free(ptr);
|
|
}
|
|
|
|
return pwm;
|
|
}
|
|
EXPORT_SYMBOL_GPL(devm_of_pwm_get);
|
|
|
|
static int devm_pwm_match(struct device *dev, void *res, void *data)
|
|
{
|
|
struct pwm_device **p = res;
|
|
|
|
if (WARN_ON(!p || !*p))
|
|
return 0;
|
|
|
|
return *p == data;
|
|
}
|
|
|
|
/**
|
|
* devm_pwm_put() - resource managed pwm_put()
|
|
* @dev: device for PWM consumer
|
|
* @pwm: PWM device
|
|
*
|
|
* Release a PWM previously allocated using devm_pwm_get(). Calling this
|
|
* function is usually not needed because devm-allocated resources are
|
|
* automatically released on driver detach.
|
|
*/
|
|
void devm_pwm_put(struct device *dev, struct pwm_device *pwm)
|
|
{
|
|
WARN_ON(devres_release(dev, devm_pwm_release, devm_pwm_match, pwm));
|
|
}
|
|
EXPORT_SYMBOL_GPL(devm_pwm_put);
|
|
|
|
#ifdef CONFIG_DEBUG_FS
|
|
static void pwm_dbg_show(struct pwm_chip *chip, struct seq_file *s)
|
|
{
|
|
unsigned int i;
|
|
|
|
for (i = 0; i < chip->npwm; i++) {
|
|
struct pwm_device *pwm = &chip->pwms[i];
|
|
struct pwm_state state;
|
|
|
|
pwm_get_state(pwm, &state);
|
|
|
|
seq_printf(s, " pwm-%-3d (%-20.20s):", i, pwm->label);
|
|
|
|
if (test_bit(PWMF_REQUESTED, &pwm->flags))
|
|
seq_puts(s, " requested");
|
|
|
|
if (state.enabled)
|
|
seq_puts(s, " enabled");
|
|
|
|
seq_printf(s, " period: %u ns", state.period);
|
|
seq_printf(s, " duty: %u ns", state.duty_cycle);
|
|
seq_printf(s, " polarity: %s",
|
|
state.polarity ? "inverse" : "normal");
|
|
|
|
seq_puts(s, "\n");
|
|
}
|
|
}
|
|
|
|
static void *pwm_seq_start(struct seq_file *s, loff_t *pos)
|
|
{
|
|
mutex_lock(&pwm_lock);
|
|
s->private = "";
|
|
|
|
return seq_list_start(&pwm_chips, *pos);
|
|
}
|
|
|
|
static void *pwm_seq_next(struct seq_file *s, void *v, loff_t *pos)
|
|
{
|
|
s->private = "\n";
|
|
|
|
return seq_list_next(v, &pwm_chips, pos);
|
|
}
|
|
|
|
static void pwm_seq_stop(struct seq_file *s, void *v)
|
|
{
|
|
mutex_unlock(&pwm_lock);
|
|
}
|
|
|
|
static int pwm_seq_show(struct seq_file *s, void *v)
|
|
{
|
|
struct pwm_chip *chip = list_entry(v, struct pwm_chip, list);
|
|
|
|
seq_printf(s, "%s%s/%s, %d PWM device%s\n", (char *)s->private,
|
|
chip->dev->bus ? chip->dev->bus->name : "no-bus",
|
|
dev_name(chip->dev), chip->npwm,
|
|
(chip->npwm != 1) ? "s" : "");
|
|
|
|
pwm_dbg_show(chip, s);
|
|
|
|
return 0;
|
|
}
|
|
|
|
static const struct seq_operations pwm_seq_ops = {
|
|
.start = pwm_seq_start,
|
|
.next = pwm_seq_next,
|
|
.stop = pwm_seq_stop,
|
|
.show = pwm_seq_show,
|
|
};
|
|
|
|
static int pwm_seq_open(struct inode *inode, struct file *file)
|
|
{
|
|
return seq_open(file, &pwm_seq_ops);
|
|
}
|
|
|
|
static const struct file_operations pwm_debugfs_ops = {
|
|
.owner = THIS_MODULE,
|
|
.open = pwm_seq_open,
|
|
.read = seq_read,
|
|
.llseek = seq_lseek,
|
|
.release = seq_release,
|
|
};
|
|
|
|
static int __init pwm_debugfs_init(void)
|
|
{
|
|
debugfs_create_file("pwm", S_IFREG | S_IRUGO, NULL, NULL,
|
|
&pwm_debugfs_ops);
|
|
|
|
return 0;
|
|
}
|
|
subsys_initcall(pwm_debugfs_init);
|
|
#endif /* CONFIG_DEBUG_FS */
|