From patchwork Tue Nov 29 14:37:04 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sudeep Holla X-Patchwork-Id: 84833 Delivered-To: patch@linaro.org Received: by 10.140.20.101 with SMTP id 92csp1623270qgi; Tue, 29 Nov 2016 06:38:01 -0800 (PST) X-Received: by 10.84.170.195 with SMTP id j61mr62716130plb.13.1480430281109; Tue, 29 Nov 2016 06:38:01 -0800 (PST) Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id r7si31602335ple.282.2016.11.29.06.38.00; Tue, 29 Nov 2016 06:38:01 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757770AbcK2Ohp (ORCPT + 25 others); Tue, 29 Nov 2016 09:37:45 -0500 Received: from foss.arm.com ([217.140.101.70]:48210 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754373AbcK2Oh1 (ORCPT ); Tue, 29 Nov 2016 09:37:27 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3D75716; Tue, 29 Nov 2016 06:37:13 -0800 (PST) Received: from e107155-lin.cambridge.arm.com (e107155-lin.cambridge.arm.com [10.1.210.28]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 5B6CE3F220; Tue, 29 Nov 2016 06:37:12 -0800 (PST) From: Sudeep Holla To: linux-kernel@vger.kernel.org, Jassi Brar Cc: Sudeep Holla , Lee Jones , Jassi Brar Subject: [PATCH 1/2] mailbox: mailbox-test: add support for fasync/poll Date: Tue, 29 Nov 2016 14:37:04 +0000 Message-Id: <1480430225-14567-1-git-send-email-sudeep.holla@arm.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Currently the read operation on the message debug file returns error if there's no data ready to be read. It expects the userspace to retry if it fails. Since the mailbox response could be asynchronous, it would be good to add support to block the read until the data is available. We can also implement poll file operations so that the userspace can wait to become ready to perform any I/O. This patch implements the poll and fasync file operation callback for the test mailbox device. Cc: Lee Jones Cc: Jassi Brar Signed-off-by: Sudeep Holla --- drivers/mailbox/mailbox-test.c | 79 +++++++++++++++++++++++++++++++++++++----- 1 file changed, 71 insertions(+), 8 deletions(-) -- 2.7.4 diff --git a/drivers/mailbox/mailbox-test.c b/drivers/mailbox/mailbox-test.c index 9ca96e9db6bf..d13f4f8a1ecf 100644 --- a/drivers/mailbox/mailbox-test.c +++ b/drivers/mailbox/mailbox-test.c @@ -11,12 +11,14 @@ #include #include +#include #include #include #include #include #include #include +#include #include #include @@ -39,6 +41,8 @@ struct mbox_test_device { char *signal; char *message; spinlock_t lock; + wait_queue_head_t waitq; + struct fasync_struct *async_queue; }; static ssize_t mbox_test_signal_write(struct file *filp, @@ -81,6 +85,13 @@ static const struct file_operations mbox_test_signal_ops = { .llseek = generic_file_llseek, }; +static int mbox_test_message_fasync(int fd, struct file *filp, int on) +{ + struct mbox_test_device *tdev = filp->private_data; + + return fasync_helper(fd, filp, on, &tdev->async_queue); +} + static ssize_t mbox_test_message_write(struct file *filp, const char __user *userbuf, size_t count, loff_t *ppos) @@ -138,6 +149,20 @@ static ssize_t mbox_test_message_write(struct file *filp, return ret < 0 ? ret : count; } +static bool mbox_test_message_data_ready(struct mbox_test_device *tdev) +{ + unsigned char data; + unsigned long flags; + + spin_lock_irqsave(&tdev->lock, flags); + data = tdev->rx_buffer[0]; + spin_unlock_irqrestore(&tdev->lock, flags); + + if (data != '\0') + return true; + return false; +} + static ssize_t mbox_test_message_read(struct file *filp, char __user *userbuf, size_t count, loff_t *ppos) { @@ -147,6 +172,8 @@ static ssize_t mbox_test_message_read(struct file *filp, char __user *userbuf, int l = 0; int ret; + DECLARE_WAITQUEUE(wait, current); + touser = kzalloc(MBOX_HEXDUMP_MAX_LEN + 1, GFP_KERNEL); if (!touser) return -ENOMEM; @@ -155,15 +182,29 @@ static ssize_t mbox_test_message_read(struct file *filp, char __user *userbuf, ret = snprintf(touser, 20, "\n"); ret = simple_read_from_buffer(userbuf, count, ppos, touser, ret); - goto out; + goto kfree_err; } - if (tdev->rx_buffer[0] == '\0') { - ret = snprintf(touser, 9, "\n"); - ret = simple_read_from_buffer(userbuf, count, ppos, - touser, ret); - goto out; - } + add_wait_queue(&tdev->waitq, &wait); + + do { + __set_current_state(TASK_INTERRUPTIBLE); + + if (mbox_test_message_data_ready(tdev)) + break; + + if (filp->f_flags & O_NONBLOCK) { + ret = -EAGAIN; + goto waitq_err; + } + + if (signal_pending(current)) { + ret = -ERESTARTSYS; + goto waitq_err; + } + schedule(); + + } while (1); spin_lock_irqsave(&tdev->lock, flags); @@ -185,14 +226,31 @@ static ssize_t mbox_test_message_read(struct file *filp, char __user *userbuf, spin_unlock_irqrestore(&tdev->lock, flags); ret = simple_read_from_buffer(userbuf, count, ppos, touser, MBOX_HEXDUMP_MAX_LEN); -out: +waitq_err: + __set_current_state(TASK_RUNNING); + remove_wait_queue(&tdev->waitq, &wait); +kfree_err: kfree(touser); return ret; } +static unsigned int +mbox_test_message_poll(struct file *filp, struct poll_table_struct *wait) +{ + struct mbox_test_device *tdev = filp->private_data; + + poll_wait(filp, &tdev->waitq, wait); + + if (mbox_test_message_data_ready(tdev)) + return POLLIN | POLLRDNORM; + return 0; +} + static const struct file_operations mbox_test_message_ops = { .write = mbox_test_message_write, .read = mbox_test_message_read, + .fasync = mbox_test_message_fasync, + .poll = mbox_test_message_poll, .open = simple_open, .llseek = generic_file_llseek, }; @@ -234,6 +292,10 @@ static void mbox_test_receive_message(struct mbox_client *client, void *message) memcpy(tdev->rx_buffer, message, MBOX_MAX_MSG_LEN); } spin_unlock_irqrestore(&tdev->lock, flags); + + wake_up_interruptible(&tdev->waitq); + + kill_fasync(&tdev->async_queue, SIGIO, POLL_IN); } static void mbox_test_prepare_message(struct mbox_client *client, void *message) @@ -334,6 +396,7 @@ static int mbox_test_probe(struct platform_device *pdev) if (ret) return ret; + init_waitqueue_head(&tdev->waitq); dev_info(&pdev->dev, "Successfully registered\n"); return 0;