| Message ID | 20200909102640.1657622-10-warthog618@gmail.com |
|---|---|
| State | Superseded |
| Headers | show |
| Series | gpio: cdev: add uAPI v2 | expand |
On Wed, Sep 9, 2020 at 1:33 PM Kent Gibson <warthog618@gmail.com> wrote: > > Add support for edge detection to lines requested using > GPIO_V2_GET_LINE_IOCTL. > > The edge_detector implementation is based on the v1 lineevent > implementation. ... > + * @timestamp: cache for the timestamp storing it between hardirq and IRQ > + * thread, used to bring the timestamp close to the actual event _ns ? > + * @req_seqno: the seqno for the current edge event in the sequence of > + * events for the corresponding line request. This is drawn from the @req. > + * @line_seqno: the seqno for the current edge event in the sequence of > + * events for this line. > */ > struct line { > struct gpio_desc *desc; > + /* > + * -- edge detector specific fields -- > + */ > + struct linereq *req; > + unsigned int irq; > + u64 eflags; > + /* > + * timestamp and req_seqno are shared by edge_irq_handler() and > + * edge_irq_thread() which are themselves mutually exclusive. > + */ I didn't quite get this comment. Does it mean we should define them as union here? Or is it about how functions consider this data and no lock is needed? Or what? > + u64 timestamp; > + u32 req_seqno; > + u32 line_seqno; > }; > > /** > @@ -395,12 +418,22 @@ struct line { > * @gdev: the GPIO device the line request pertains to > * @label: consumer label used to tag GPIO descriptors > * @num_lines: the number of lines in the lines array > + * @wait: wait queue that handles blocking reads of events > + * @event_buffer_size: the number of elements allocated in @events > + * @events: KFIFO for the GPIO events > + * @seqno: the sequence number for edge events generated on all lines in > + * this line request. Note that this is not used when @num_lines is 1, as > + * the line_seqno is then the same and is cheaper to calculate. > * @lines: the lines held by this line request, with @num_lines elements. > */ > struct linereq { > struct gpio_device *gdev; > const char *label; > u32 num_lines; > + wait_queue_head_t wait; > + u32 event_buffer_size; > + DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event); > + atomic_t seqno; > struct line lines[]; > }; > > @@ -417,12 +450,138 @@ struct linereq { > (GPIO_V2_LINE_FLAG_OPEN_DRAIN | \ > GPIO_V2_LINE_FLAG_OPEN_SOURCE) > > +#define GPIO_V2_LINE_EDGE_FLAGS \ > + (GPIO_V2_LINE_FLAG_EDGE_RISING | \ > + GPIO_V2_LINE_FLAG_EDGE_FALLING) > + > #define GPIO_V2_LINE_VALID_FLAGS \ > (GPIO_V2_LINE_FLAG_ACTIVE_LOW | \ > GPIO_V2_LINE_DIRECTION_FLAGS | \ > GPIO_V2_LINE_DRIVE_FLAGS | \ > + GPIO_V2_LINE_EDGE_FLAGS | \ > GPIO_V2_LINE_BIAS_FLAGS) > > +static irqreturn_t edge_irq_thread(int irq, void *p) > +{ > + struct line *line = p; > + struct linereq *lr = line->req; > + struct gpio_v2_line_event le; > + int ret; > + > + /* Do not leak kernel stack to userspace */ > + memset(&le, 0, sizeof(le)); > + > + /* > + * We may be running from a nested threaded interrupt in which case > + * we didn't get the timestamp from edge_irq_handler(). > + */ > + if (!line->timestamp) { Can it be positive conditional? > + le.timestamp = ktime_get_ns(); > + if (lr->num_lines != 1) > + line->req_seqno = atomic_inc_return(&lr->seqno); > + } else { > + le.timestamp = line->timestamp; > + } > + line->timestamp = 0; > + > + if (line->eflags == (GPIO_V2_LINE_FLAG_EDGE_RISING | > + GPIO_V2_LINE_FLAG_EDGE_FALLING)) { > + int level = gpiod_get_value_cansleep(line->desc); > + > + if (level) > + /* Emit low-to-high event */ > + le.id = GPIO_V2_LINE_EVENT_RISING_EDGE; > + else > + /* Emit high-to-low event */ > + le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE; > + } else if (line->eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) { > + /* Emit low-to-high event */ > + le.id = GPIO_V2_LINE_EVENT_RISING_EDGE; > + } else if (line->eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) { > + /* Emit high-to-low event */ > + le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE; > + } else { > + return IRQ_NONE; > + } > + line->line_seqno++; > + le.line_seqno = line->line_seqno; > + le.seqno = (lr->num_lines == 1) ? le.line_seqno : line->req_seqno; > + le.offset = gpio_chip_hwgpio(line->desc); > + > + ret = kfifo_in_spinlocked_noirqsave(&lr->events, &le, > + 1, &lr->wait.lock); > + if (ret) > + wake_up_poll(&lr->wait, EPOLLIN); > + else > + pr_debug_ratelimited("event FIFO is full - event dropped\n"); Oh, can we really avoid printf() in IRQ context? > + return IRQ_HANDLED; > +} > + > +static irqreturn_t edge_irq_handler(int irq, void *p) > +{ > + struct line *line = p; > + struct linereq *lr = line->req; > + > + /* > + * Just store the timestamp in hardirq context so we get it as > + * close in time as possible to the actual event. > + */ > + line->timestamp = ktime_get_ns(); > + > + if (lr->num_lines != 1) > + line->req_seqno = atomic_inc_return(&lr->seqno); > + > + return IRQ_WAKE_THREAD; > +} > + > +static void edge_detector_stop(struct line *line) > +{ > + if (line->irq) { > + free_irq(line->irq, line); > + line->irq = 0; > + } Perhaps if (!line->irq) return; ? > +} > + > +static int edge_detector_setup(struct line *line, > + u64 eflags) > +{ > + unsigned long irqflags = 0; > + int irq, ret; > + > + if (eflags && !kfifo_initialized(&line->req->events)) { > + ret = kfifo_alloc(&line->req->events, > + line->req->event_buffer_size, GFP_KERNEL); > + if (ret) > + return ret; > + } > + line->eflags = eflags; > + > + if (!eflags) > + return 0; > + > + irq = gpiod_to_irq(line->desc); > + if (irq <= 0) > + return -ENODEV; Why shadowing actual error code? > + if (eflags & GPIO_V2_LINE_FLAG_EDGE_RISING) > + irqflags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ? > + IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; > + if (eflags & GPIO_V2_LINE_FLAG_EDGE_FALLING) > + irqflags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ? > + IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING; > + irqflags |= IRQF_ONESHOT; > + > + /* Request a thread to read the events */ > + ret = request_threaded_irq(irq, edge_irq_handler, edge_irq_thread, > + irqflags, line->req->label, line); > + if (ret) > + return ret; > + > + line->irq = irq; > + return 0; > +} > + > static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc, > unsigned int line_idx) > { > @@ -465,6 +624,11 @@ static int gpio_v2_line_flags_validate(u64 flags) > (flags & GPIO_V2_LINE_FLAG_OUTPUT)) > return -EINVAL; > > + /* Edge detection requires explicit input. */ > + if ((flags & GPIO_V2_LINE_EDGE_FLAGS) && > + !(flags & GPIO_V2_LINE_FLAG_INPUT)) > + return -EINVAL; > + > /* > * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If > * the hardware actually supports enabling both at the same time the > @@ -526,6 +690,10 @@ static void gpio_v2_line_config_flags_to_desc_flags(u64 flags, > set_bit(FLAG_IS_OUT, flagsp); > else if (flags & GPIO_V2_LINE_FLAG_INPUT) > clear_bit(FLAG_IS_OUT, flagsp); > + assign_bit(FLAG_EDGE_RISING, flagsp, > + flags & GPIO_V2_LINE_FLAG_EDGE_RISING); > + assign_bit(FLAG_EDGE_FALLING, flagsp, > + flags & GPIO_V2_LINE_FLAG_EDGE_FALLING); > assign_bit(FLAG_OPEN_DRAIN, flagsp, > flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN); > assign_bit(FLAG_OPEN_SOURCE, flagsp, > @@ -614,14 +782,85 @@ static long linereq_ioctl_compat(struct file *file, unsigned int cmd, > } > #endif > > +static __poll_t linereq_poll(struct file *file, > + struct poll_table_struct *wait) > +{ > + struct linereq *lr = file->private_data; > + __poll_t events = 0; > + > + poll_wait(file, &lr->wait, wait); > + > + if (!kfifo_is_empty_spinlocked_noirqsave(&lr->events, > + &lr->wait.lock)) > + events = EPOLLIN | EPOLLRDNORM; > + > + return events; > +} > + > +static ssize_t linereq_read(struct file *file, > + char __user *buf, > + size_t count, > + loff_t *f_ps) > +{ > + struct linereq *lr = file->private_data; > + struct gpio_v2_line_event le; > + ssize_t bytes_read = 0; > + int ret; > + > + if (count < sizeof(le)) > + return -EINVAL; > + > + do { > + spin_lock(&lr->wait.lock); > + if (kfifo_is_empty(&lr->events)) { > + if (bytes_read) { > + spin_unlock(&lr->wait.lock); > + return bytes_read; > + } > + > + if (file->f_flags & O_NONBLOCK) { > + spin_unlock(&lr->wait.lock); > + return -EAGAIN; > + } > + > + ret = wait_event_interruptible_locked(lr->wait, > + !kfifo_is_empty(&lr->events)); > + if (ret) { > + spin_unlock(&lr->wait.lock); > + return ret; > + } > + } > + > + ret = kfifo_out(&lr->events, &le, 1); > + spin_unlock(&lr->wait.lock); > + if (ret != 1) { > + /* > + * This should never happen - we were holding the > + * lock from the moment we learned the fifo is no > + * longer empty until now. > + */ > + ret = -EIO; > + break; > + } > + > + if (copy_to_user(buf + bytes_read, &le, sizeof(le))) > + return -EFAULT; > + bytes_read += sizeof(le); > + } while (count >= bytes_read + sizeof(le)); > + > + return bytes_read; > +} > + > static void linereq_free(struct linereq *lr) > { > unsigned int i; > > for (i = 0; i < lr->num_lines; i++) { > + edge_detector_stop(&lr->lines[i]); > if (lr->lines[i].desc) > gpiod_free(lr->lines[i].desc); > } > + kfifo_free(&lr->events); > kfree(lr->label); > put_device(&lr->gdev->dev); > kfree(lr); > @@ -637,6 +876,8 @@ static int linereq_release(struct inode *inode, struct file *file) > > static const struct file_operations line_fileops = { > .release = linereq_release, > + .read = linereq_read, > + .poll = linereq_poll, > .owner = THIS_MODULE, > .llseek = noop_llseek, > .unlocked_ioctl = linereq_ioctl, > @@ -676,6 +917,9 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) > lr->gdev = gdev; > get_device(&gdev->dev); > > + for (i = 0; i < ulr.num_lines; i++) > + lr->lines[i].req = lr; > /* Make sure this is terminated */ > ulr.consumer[sizeof(ulr.consumer)-1] = '\0'; > if (strlen(ulr.consumer)) { > @@ -686,6 +930,14 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) > } > } > > + init_waitqueue_head(&lr->wait); > + lr->event_buffer_size = ulr.event_buffer_size; > + if (lr->event_buffer_size == 0) > + lr->event_buffer_size = ulr.num_lines*16; > + else if (lr->event_buffer_size > GPIO_V2_LINES_MAX*16) > + lr->event_buffer_size = GPIO_V2_LINES_MAX*16; *16 -> ' * 16' > + > + atomic_set(&lr->seqno, 0); > lr->num_lines = ulr.num_lines; > > /* Request each GPIO */ > @@ -724,6 +976,11 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) > ret = gpiod_direction_input(desc); > if (ret) > goto out_free_linereq; > + > + ret = edge_detector_setup(&lr->lines[i], > + flags & GPIO_V2_LINE_EDGE_FLAGS); > + if (ret) > + goto out_free_linereq; > } > > blocking_notifier_call_chain(&desc->gdev->notifier, > @@ -1245,6 +1502,11 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc, > if (test_bit(FLAG_PULL_UP, &desc->flags)) > info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP; > > + if (test_bit(FLAG_EDGE_RISING, &desc->flags)) > + info->flags |= GPIO_V2_LINE_FLAG_EDGE_RISING; > + if (test_bit(FLAG_EDGE_FALLING, &desc->flags)) > + info->flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING; > + > spin_unlock_irqrestore(&gpio_lock, flags); > } > > diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c > index 80137c1b3cdc..e4c81dca7f8b 100644 > --- a/drivers/gpio/gpiolib.c > +++ b/drivers/gpio/gpiolib.c > @@ -2041,6 +2041,8 @@ static bool gpiod_free_commit(struct gpio_desc *desc) > clear_bit(FLAG_PULL_UP, &desc->flags); > clear_bit(FLAG_PULL_DOWN, &desc->flags); > clear_bit(FLAG_BIAS_DISABLE, &desc->flags); > + clear_bit(FLAG_EDGE_RISING, &desc->flags); > + clear_bit(FLAG_EDGE_FALLING, &desc->flags); > clear_bit(FLAG_IS_HOGGED, &desc->flags); > #ifdef CONFIG_OF_DYNAMIC > desc->hog = NULL; > diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h > index 6709f79c02dd..39b356160937 100644 > --- a/drivers/gpio/gpiolib.h > +++ b/drivers/gpio/gpiolib.h > @@ -114,6 +114,8 @@ struct gpio_desc { > #define FLAG_PULL_UP 13 /* GPIO has pull up enabled */ > #define FLAG_PULL_DOWN 14 /* GPIO has pull down enabled */ > #define FLAG_BIAS_DISABLE 15 /* GPIO has pull disabled */ > +#define FLAG_EDGE_RISING 16 /* GPIO CDEV detects rising edge events */ > +#define FLAG_EDGE_FALLING 17 /* GPIO CDEV detects falling edge events */ > > /* Connection label */ > const char *label; > -- > 2.28.0 > -- With Best Regards, Andy Shevchenko
On Tue, Sep 15, 2020 at 01:39:41PM +0300, Andy Shevchenko wrote: > On Wed, Sep 9, 2020 at 1:33 PM Kent Gibson <warthog618@gmail.com> wrote: > > > > Add support for edge detection to lines requested using > > GPIO_V2_GET_LINE_IOCTL. > > > > The edge_detector implementation is based on the v1 lineevent > > implementation. > > Hi Andy, Thanks for all the review comments. I'm hoping to address them and get a v9 out in the next few days. Do you have any comments for the remaining patches - particularly 10-12 that complete the kernel implementation? Thanks, Kent.
On Fri, Sep 18, 2020 at 3:44 PM Kent Gibson <warthog618@gmail.com> wrote: > On Tue, Sep 15, 2020 at 01:39:41PM +0300, Andy Shevchenko wrote: > > On Wed, Sep 9, 2020 at 1:33 PM Kent Gibson <warthog618@gmail.com> wrote: > > > > > > Add support for edge detection to lines requested using > > > GPIO_V2_GET_LINE_IOCTL. > > > > > > The edge_detector implementation is based on the v1 lineevent > > > implementation. > Thanks for all the review comments. I'm hoping to address them and get > a v9 out in the next few days. Do you have any comments for the > remaining patches - particularly 10-12 that complete the kernel > implementation? Probably. I will do my best to review the rest, though I've been quite overloaded the last few weeks with different stuff. -- With Best Regards, Andy Shevchenko
On Tue, Sep 15, 2020 at 01:39:41PM +0300, Andy Shevchenko wrote: > On Wed, Sep 9, 2020 at 1:33 PM Kent Gibson <warthog618@gmail.com> wrote: > > > > Add support for edge detection to lines requested using > > GPIO_V2_GET_LINE_IOCTL. > > > > The edge_detector implementation is based on the v1 lineevent > > implementation. > > ... > [snip] > > + > > + /* > > + * We may be running from a nested threaded interrupt in which case > > + * we didn't get the timestamp from edge_irq_handler(). > > + */ > > > + if (!line->timestamp) { > > Can it be positive conditional? > Not sure what you mean - switch the order of the if/else? > > + le.timestamp = ktime_get_ns(); > > + if (lr->num_lines != 1) > > + line->req_seqno = atomic_inc_return(&lr->seqno); > > + } else { > > + le.timestamp = line->timestamp; > > + } > > + line->timestamp = 0; > > + > > + if (line->eflags == (GPIO_V2_LINE_FLAG_EDGE_RISING | > > + GPIO_V2_LINE_FLAG_EDGE_FALLING)) { > > + int level = gpiod_get_value_cansleep(line->desc); > > + > > + if (level) > > + /* Emit low-to-high event */ > > + le.id = GPIO_V2_LINE_EVENT_RISING_EDGE; > > + else > > + /* Emit high-to-low event */ > > + le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE; > > + } else if (line->eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) { > > + /* Emit low-to-high event */ > > + le.id = GPIO_V2_LINE_EVENT_RISING_EDGE; > > + } else if (line->eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) { > > + /* Emit high-to-low event */ > > + le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE; > > + } else { > > + return IRQ_NONE; > > + } > > + line->line_seqno++; > > + le.line_seqno = line->line_seqno; > > + le.seqno = (lr->num_lines == 1) ? le.line_seqno : line->req_seqno; > > + le.offset = gpio_chip_hwgpio(line->desc); > > + > > + ret = kfifo_in_spinlocked_noirqsave(&lr->events, &le, > > + 1, &lr->wait.lock); > > + if (ret) > > + wake_up_poll(&lr->wait, EPOLLIN); > > + else > > > + pr_debug_ratelimited("event FIFO is full - event dropped\n"); > > Oh, can we really avoid printf() in IRQ context? > Even in the IRQ thread? Would a tracepoint be preferable? Btw, this is drawn from the v1 implmentation. > > + > > +static void edge_detector_stop(struct line *line) > > +{ > > > + if (line->irq) { > > + free_irq(line->irq, line); > > + line->irq = 0; > > + } > > Perhaps > > if (!line->irq) > return; > > ? > No - the function is extended in subsequent patches. I usually make a note of cases like this in the commentary, but missed this one. > > + if (!eflags) > > + return 0; > > + > > + irq = gpiod_to_irq(line->desc); > > + if (irq <= 0) > > > + return -ENODEV; > > Why shadowing actual error code? > Another one drawn from the v1 implementation, so not sure. gpiod_to_irq() can potentially return EINVAL, which is definitely not appropriate to return, or ENXIO, which is actually more appropriate?? Cheers, Kent.
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c index a0aa1ff1124a..7161c8921298 100644 --- a/drivers/gpio/gpiolib-cdev.c +++ b/drivers/gpio/gpiolib-cdev.c @@ -385,9 +385,32 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip) /** * struct line - contains the state of a requested line * @desc: the GPIO descriptor for this line. + * @req: the corresponding line request + * @irq: the interrupt triggered in response to events on this GPIO + * @eflags: the edge flags, GPIO_V2_LINE_FLAG_EDGE_RISING and/or + * GPIO_V2_LINE_FLAG_EDGE_FALLING, indicating the edge detection applied + * @timestamp: cache for the timestamp storing it between hardirq and IRQ + * thread, used to bring the timestamp close to the actual event + * @req_seqno: the seqno for the current edge event in the sequence of + * events for the corresponding line request. This is drawn from the @req. + * @line_seqno: the seqno for the current edge event in the sequence of + * events for this line. */ struct line { struct gpio_desc *desc; + /* + * -- edge detector specific fields -- + */ + struct linereq *req; + unsigned int irq; + u64 eflags; + /* + * timestamp and req_seqno are shared by edge_irq_handler() and + * edge_irq_thread() which are themselves mutually exclusive. + */ + u64 timestamp; + u32 req_seqno; + u32 line_seqno; }; /** @@ -395,12 +418,22 @@ struct line { * @gdev: the GPIO device the line request pertains to * @label: consumer label used to tag GPIO descriptors * @num_lines: the number of lines in the lines array + * @wait: wait queue that handles blocking reads of events + * @event_buffer_size: the number of elements allocated in @events + * @events: KFIFO for the GPIO events + * @seqno: the sequence number for edge events generated on all lines in + * this line request. Note that this is not used when @num_lines is 1, as + * the line_seqno is then the same and is cheaper to calculate. * @lines: the lines held by this line request, with @num_lines elements. */ struct linereq { struct gpio_device *gdev; const char *label; u32 num_lines; + wait_queue_head_t wait; + u32 event_buffer_size; + DECLARE_KFIFO_PTR(events, struct gpio_v2_line_event); + atomic_t seqno; struct line lines[]; }; @@ -417,12 +450,138 @@ struct linereq { (GPIO_V2_LINE_FLAG_OPEN_DRAIN | \ GPIO_V2_LINE_FLAG_OPEN_SOURCE) +#define GPIO_V2_LINE_EDGE_FLAGS \ + (GPIO_V2_LINE_FLAG_EDGE_RISING | \ + GPIO_V2_LINE_FLAG_EDGE_FALLING) + #define GPIO_V2_LINE_VALID_FLAGS \ (GPIO_V2_LINE_FLAG_ACTIVE_LOW | \ GPIO_V2_LINE_DIRECTION_FLAGS | \ GPIO_V2_LINE_DRIVE_FLAGS | \ + GPIO_V2_LINE_EDGE_FLAGS | \ GPIO_V2_LINE_BIAS_FLAGS) +static irqreturn_t edge_irq_thread(int irq, void *p) +{ + struct line *line = p; + struct linereq *lr = line->req; + struct gpio_v2_line_event le; + int ret; + + /* Do not leak kernel stack to userspace */ + memset(&le, 0, sizeof(le)); + + /* + * We may be running from a nested threaded interrupt in which case + * we didn't get the timestamp from edge_irq_handler(). + */ + if (!line->timestamp) { + le.timestamp = ktime_get_ns(); + if (lr->num_lines != 1) + line->req_seqno = atomic_inc_return(&lr->seqno); + } else { + le.timestamp = line->timestamp; + } + line->timestamp = 0; + + if (line->eflags == (GPIO_V2_LINE_FLAG_EDGE_RISING | + GPIO_V2_LINE_FLAG_EDGE_FALLING)) { + int level = gpiod_get_value_cansleep(line->desc); + + if (level) + /* Emit low-to-high event */ + le.id = GPIO_V2_LINE_EVENT_RISING_EDGE; + else + /* Emit high-to-low event */ + le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE; + } else if (line->eflags == GPIO_V2_LINE_FLAG_EDGE_RISING) { + /* Emit low-to-high event */ + le.id = GPIO_V2_LINE_EVENT_RISING_EDGE; + } else if (line->eflags == GPIO_V2_LINE_FLAG_EDGE_FALLING) { + /* Emit high-to-low event */ + le.id = GPIO_V2_LINE_EVENT_FALLING_EDGE; + } else { + return IRQ_NONE; + } + line->line_seqno++; + le.line_seqno = line->line_seqno; + le.seqno = (lr->num_lines == 1) ? le.line_seqno : line->req_seqno; + le.offset = gpio_chip_hwgpio(line->desc); + + ret = kfifo_in_spinlocked_noirqsave(&lr->events, &le, + 1, &lr->wait.lock); + if (ret) + wake_up_poll(&lr->wait, EPOLLIN); + else + pr_debug_ratelimited("event FIFO is full - event dropped\n"); + + return IRQ_HANDLED; +} + +static irqreturn_t edge_irq_handler(int irq, void *p) +{ + struct line *line = p; + struct linereq *lr = line->req; + + /* + * Just store the timestamp in hardirq context so we get it as + * close in time as possible to the actual event. + */ + line->timestamp = ktime_get_ns(); + + if (lr->num_lines != 1) + line->req_seqno = atomic_inc_return(&lr->seqno); + + return IRQ_WAKE_THREAD; +} + +static void edge_detector_stop(struct line *line) +{ + if (line->irq) { + free_irq(line->irq, line); + line->irq = 0; + } +} + +static int edge_detector_setup(struct line *line, + u64 eflags) +{ + unsigned long irqflags = 0; + int irq, ret; + + if (eflags && !kfifo_initialized(&line->req->events)) { + ret = kfifo_alloc(&line->req->events, + line->req->event_buffer_size, GFP_KERNEL); + if (ret) + return ret; + } + line->eflags = eflags; + + if (!eflags) + return 0; + + irq = gpiod_to_irq(line->desc); + if (irq <= 0) + return -ENODEV; + + if (eflags & GPIO_V2_LINE_FLAG_EDGE_RISING) + irqflags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ? + IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; + if (eflags & GPIO_V2_LINE_FLAG_EDGE_FALLING) + irqflags |= test_bit(FLAG_ACTIVE_LOW, &line->desc->flags) ? + IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING; + irqflags |= IRQF_ONESHOT; + + /* Request a thread to read the events */ + ret = request_threaded_irq(irq, edge_irq_handler, edge_irq_thread, + irqflags, line->req->label, line); + if (ret) + return ret; + + line->irq = irq; + return 0; +} + static u64 gpio_v2_line_config_flags(struct gpio_v2_line_config *lc, unsigned int line_idx) { @@ -465,6 +624,11 @@ static int gpio_v2_line_flags_validate(u64 flags) (flags & GPIO_V2_LINE_FLAG_OUTPUT)) return -EINVAL; + /* Edge detection requires explicit input. */ + if ((flags & GPIO_V2_LINE_EDGE_FLAGS) && + !(flags & GPIO_V2_LINE_FLAG_INPUT)) + return -EINVAL; + /* * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If * the hardware actually supports enabling both at the same time the @@ -526,6 +690,10 @@ static void gpio_v2_line_config_flags_to_desc_flags(u64 flags, set_bit(FLAG_IS_OUT, flagsp); else if (flags & GPIO_V2_LINE_FLAG_INPUT) clear_bit(FLAG_IS_OUT, flagsp); + assign_bit(FLAG_EDGE_RISING, flagsp, + flags & GPIO_V2_LINE_FLAG_EDGE_RISING); + assign_bit(FLAG_EDGE_FALLING, flagsp, + flags & GPIO_V2_LINE_FLAG_EDGE_FALLING); assign_bit(FLAG_OPEN_DRAIN, flagsp, flags & GPIO_V2_LINE_FLAG_OPEN_DRAIN); assign_bit(FLAG_OPEN_SOURCE, flagsp, @@ -614,14 +782,85 @@ static long linereq_ioctl_compat(struct file *file, unsigned int cmd, } #endif +static __poll_t linereq_poll(struct file *file, + struct poll_table_struct *wait) +{ + struct linereq *lr = file->private_data; + __poll_t events = 0; + + poll_wait(file, &lr->wait, wait); + + if (!kfifo_is_empty_spinlocked_noirqsave(&lr->events, + &lr->wait.lock)) + events = EPOLLIN | EPOLLRDNORM; + + return events; +} + +static ssize_t linereq_read(struct file *file, + char __user *buf, + size_t count, + loff_t *f_ps) +{ + struct linereq *lr = file->private_data; + struct gpio_v2_line_event le; + ssize_t bytes_read = 0; + int ret; + + if (count < sizeof(le)) + return -EINVAL; + + do { + spin_lock(&lr->wait.lock); + if (kfifo_is_empty(&lr->events)) { + if (bytes_read) { + spin_unlock(&lr->wait.lock); + return bytes_read; + } + + if (file->f_flags & O_NONBLOCK) { + spin_unlock(&lr->wait.lock); + return -EAGAIN; + } + + ret = wait_event_interruptible_locked(lr->wait, + !kfifo_is_empty(&lr->events)); + if (ret) { + spin_unlock(&lr->wait.lock); + return ret; + } + } + + ret = kfifo_out(&lr->events, &le, 1); + spin_unlock(&lr->wait.lock); + if (ret != 1) { + /* + * This should never happen - we were holding the + * lock from the moment we learned the fifo is no + * longer empty until now. + */ + ret = -EIO; + break; + } + + if (copy_to_user(buf + bytes_read, &le, sizeof(le))) + return -EFAULT; + bytes_read += sizeof(le); + } while (count >= bytes_read + sizeof(le)); + + return bytes_read; +} + static void linereq_free(struct linereq *lr) { unsigned int i; for (i = 0; i < lr->num_lines; i++) { + edge_detector_stop(&lr->lines[i]); if (lr->lines[i].desc) gpiod_free(lr->lines[i].desc); } + kfifo_free(&lr->events); kfree(lr->label); put_device(&lr->gdev->dev); kfree(lr); @@ -637,6 +876,8 @@ static int linereq_release(struct inode *inode, struct file *file) static const struct file_operations line_fileops = { .release = linereq_release, + .read = linereq_read, + .poll = linereq_poll, .owner = THIS_MODULE, .llseek = noop_llseek, .unlocked_ioctl = linereq_ioctl, @@ -676,6 +917,9 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) lr->gdev = gdev; get_device(&gdev->dev); + for (i = 0; i < ulr.num_lines; i++) + lr->lines[i].req = lr; + /* Make sure this is terminated */ ulr.consumer[sizeof(ulr.consumer)-1] = '\0'; if (strlen(ulr.consumer)) { @@ -686,6 +930,14 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) } } + init_waitqueue_head(&lr->wait); + lr->event_buffer_size = ulr.event_buffer_size; + if (lr->event_buffer_size == 0) + lr->event_buffer_size = ulr.num_lines*16; + else if (lr->event_buffer_size > GPIO_V2_LINES_MAX*16) + lr->event_buffer_size = GPIO_V2_LINES_MAX*16; + + atomic_set(&lr->seqno, 0); lr->num_lines = ulr.num_lines; /* Request each GPIO */ @@ -724,6 +976,11 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip) ret = gpiod_direction_input(desc); if (ret) goto out_free_linereq; + + ret = edge_detector_setup(&lr->lines[i], + flags & GPIO_V2_LINE_EDGE_FLAGS); + if (ret) + goto out_free_linereq; } blocking_notifier_call_chain(&desc->gdev->notifier, @@ -1245,6 +1502,11 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc, if (test_bit(FLAG_PULL_UP, &desc->flags)) info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_UP; + if (test_bit(FLAG_EDGE_RISING, &desc->flags)) + info->flags |= GPIO_V2_LINE_FLAG_EDGE_RISING; + if (test_bit(FLAG_EDGE_FALLING, &desc->flags)) + info->flags |= GPIO_V2_LINE_FLAG_EDGE_FALLING; + spin_unlock_irqrestore(&gpio_lock, flags); } diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 80137c1b3cdc..e4c81dca7f8b 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -2041,6 +2041,8 @@ static bool gpiod_free_commit(struct gpio_desc *desc) clear_bit(FLAG_PULL_UP, &desc->flags); clear_bit(FLAG_PULL_DOWN, &desc->flags); clear_bit(FLAG_BIAS_DISABLE, &desc->flags); + clear_bit(FLAG_EDGE_RISING, &desc->flags); + clear_bit(FLAG_EDGE_FALLING, &desc->flags); clear_bit(FLAG_IS_HOGGED, &desc->flags); #ifdef CONFIG_OF_DYNAMIC desc->hog = NULL; diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 6709f79c02dd..39b356160937 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -114,6 +114,8 @@ struct gpio_desc { #define FLAG_PULL_UP 13 /* GPIO has pull up enabled */ #define FLAG_PULL_DOWN 14 /* GPIO has pull down enabled */ #define FLAG_BIAS_DISABLE 15 /* GPIO has pull disabled */ +#define FLAG_EDGE_RISING 16 /* GPIO CDEV detects rising edge events */ +#define FLAG_EDGE_FALLING 17 /* GPIO CDEV detects falling edge events */ /* Connection label */ const char *label;
Add support for edge detection to lines requested using GPIO_V2_GET_LINE_IOCTL. The edge_detector implementation is based on the v1 lineevent implementation. Signed-off-by: Kent Gibson <warthog618@gmail.com> --- drivers/gpio/gpiolib-cdev.c | 262 ++++++++++++++++++++++++++++++++++++ drivers/gpio/gpiolib.c | 2 + drivers/gpio/gpiolib.h | 2 + 3 files changed, 266 insertions(+)